cmd/ctrld: only write to config file if listener config changed

Updates #149

.dockerignore

@@ -0,0 +1,2 @@
+Dockerfile
+.git/

.gitignore

@@ -1,3 +1,5 @@
-
 dist/
 gon.hcl
+
+/Build
+.DS_Store

.goreleaser-darwin.yaml

@@ -9,6 +9,8 @@ builds:
       - -trimpath
     ldflags:
       - -s -w
+      - -X main.version={{.Version}}
+      - -X main.commit={{.Commit}}
     goos:
       - darwin
     goarch:

.goreleaser-qf.yaml

@@ -9,11 +9,15 @@ builds:
       - -trimpath
     ldflags:
       - -s -w
+      - -X main.version={{.Version}}
+      - -X main.commit={{.Commit}}
     goos:
       - darwin
       - linux
       - windows
     goarch:
+      - 386
+      - arm
       - amd64
       - arm64
     tags:

.goreleaser.yaml

@@ -9,6 +9,8 @@ builds:
       - -trimpath
     ldflags:
       - -s -w
+      - -X main.version={{.Version}}
+      - -X main.commit={{.Commit}}
     goos:
       - linux
       - freebsd
@@ -17,6 +19,7 @@ builds:
       - 386
       - arm
       - mips
+      - mipsle
       - amd64
       - arm64
     goarm:

Dockerfile

@@ -0,0 +1,32 @@
+# Using Debian bullseye for building regular image.
+# Using scratch image for minimal image size.
+# The final image has:
+#
+# - Timezone info file.
+# - CA certs file.
+# - /etc/{passwd,group} file.
+# - Non-cgo ctrld binary.
+#
+# CI_COMMIT_TAG is used to set the version of ctrld binary.
+FROM golang:bullseye as base
+
+WORKDIR /app
+
+RUN apt-get update && apt-get install -y upx-ucl
+
+COPY . .
+
+ARG tag=master
+ENV CI_COMMIT_TAG=$tag
+RUN CTRLD_NO_QF=yes CGO_ENABLED=0 ./scripts/build.sh
+
+FROM scratch
+
+COPY --from=base /usr/share/zoneinfo /usr/share/zoneinfo
+COPY --from=base /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
+COPY --from=base /etc/passwd /etc/passwd
+COPY --from=base /etc/group /etc/group
+
+COPY --from=base /app/ctrld-linux-*-nocgo ctrld
+
+ENTRYPOINT ["./ctrld", "run"]

README.md

@@ -9,6 +9,11 @@ A highly configurable DNS forwarding proxy with support for:
 - Multiple upstreams with fallbacks
 - Multiple network policy driven DNS query steering
 - Policy driven domain based "split horizon" DNS with wildcard support
+- Integrations with common router vendors and firmware
+- LAN client discovery via DHCP, mDNS, and ARP
+
+## TLDR
+Proxy legacy DNS traffic to secure DNS upstreams in highly configurable ways. 
 
 All DNS protocols are supported, including:
 - `UDP 53`
@@ -17,23 +22,46 @@ All DNS protocols are supported, including:
 - `DNS-over-HTTP/3` (DOH3)
 - `DNS-over-QUIC`
 
-## Use Cases
+# Use Cases
 1. Use secure DNS protocols on networks and devices that don't natively support them (legacy routers, legacy OSes, TVs, smart toasters).
 2. Create source IP based DNS routing policies with variable secure DNS upstreams. Subnet 1 (admin) uses upstream resolver A, while Subnet 2 (employee) uses upstream resolver B.
 3. Create destination IP based DNS routing policies with variable secure DNS upstreams. Listener 1 uses upstream resolver C, while Listener 2 uses upstream resolver D.
 4. Create domain level "split horizon" DNS routing policies to send internal domains (*.company.int) to a local DNS server, while everything else goes to another upstream.
+5. Deploy on a router and create LAN client specific DNS routing policies from a web GUI (When using ControlD.com).
 
 
 ## OS Support
 - Windows (386, amd64, arm)
 - Mac (amd64, arm64)
 - Linux (386, amd64, arm, mips)
+- FreeBSD
+- Common routers (See Router Mode below)
 
-## Download
+# Install
-Download pre-compiled binaries from the [Releases](https://github.com/Control-D-Inc/ctrld/releases) section.
+There are several ways to download and install `ctrld.
+
+## Quick Install
+The simplest way to download and install `ctrld` is to use the following installer command on any UNIX-like platform:
+
+```shell
+sh -c 'sh -c "$(curl -sL https://api.controld.com/dl)"'
+```
+
+Windows user and prefer Powershell (who doesn't)? No problem, execute this command instead in administrative cmd:
+```shell
+powershell -Command "(Invoke-WebRequest -Uri 'https://api.controld.com/dl' -UseBasicParsing).Content | Set-Content 'ctrld_install.bat'" && ctrld_install.bat
+```
+
+Or you can pull and run a Docker container from [Docker Hub](https://hub.docker.com/r/controldns/ctrld)
+```
+$ docker pull controldns/ctrld
+```
+
+## Download Manually
+Alternatively, if you know what you're doing you can download pre-compiled binaries from the [Releases](https://github.com/Control-D-Inc/ctrld/releases) section for the appropriate platform. 
 
 ## Build
-`ctrld` requires `go1.19+`:
+Lastly, you can build `ctrld` from source which requires `go1.19+`:
 
 ```shell
 $ go build ./cmd/ctrld
@@ -45,6 +73,17 @@ or
 $ go install github.com/Control-D-Inc/ctrld/cmd/ctrld@latest
 ```
 
+or 
+
+```
+$ docker build -t controldns/ctrld .
+$ docker run -d --name=ctrld -p 53:53/tcp -p 53:53/udp controldns/ctrld --cd=RESOLVER_ID_GOES_HERE -vv
+```
+
+
+# Usage
+The cli is self documenting, so free free to run `--help` on any sub-command to get specific usages. 
+
 ## Arguments
 ```
         __         .__       .___
@@ -60,18 +99,23 @@ Usage:
 Available Commands:
   run         Run the DNS proxy server
   service     Manage ctrld service
-  start       Quick start service and configure DNS on default interface
+  start       Quick start service and configure DNS on interface
-  stop        Quick stop service and remove DNS from default interface
+  stop        Quick stop service and remove DNS from interface
+  restart     Restart the ctrld service
+  status      Show status of the ctrld service
+  uninstall   Stop and uninstall the ctrld service
+  clients     Manage clients
 
 Flags:
   -h, --help            help for ctrld
+  -s, --silent          do not write any log output
   -v, --verbose count   verbose log output, "-v" basic logging, "-vv" debug level logging
       --version         version for ctrld
 
 Use "ctrld [command] --help" for more information about a command.
 ```
 
-## Usage
+## Basic Run Mode
 To start the server with default configuration, simply run: `./ctrld run`. This will create a generic `ctrld.toml` file in the **working directory** and start the application in foreground. 
 1. Start the server
   ```
@@ -85,40 +129,33 @@ To start the server with default configuration, simply run: `./ctrld run`. This
   147.185.34.1
   ```
 
-If `verify.controld.com` resolves, you're successfully using the default Control D upstream.
+If `verify.controld.com` resolves, you're successfully using the default Control D upstream. From here, you can start editing the config file and go nuts with it. To enforce a new config, restart the server. 
 
-### Service Mode
+## Service Mode
-To run the application in service mode, simply run: `./ctrld start` as system/root user. This will create a generic `ctrld.toml` file in the **user home** directory, start the system service, and configure the listener on the default interface. Service will start on OS boot.
+To run the application in service mode on any Windows, MacOS, Linux distibution or supported router, simply run: `./ctrld start` as system/root user. This will create a generic `ctrld.toml` file in the **user home** directory (on Windows) or `/etc/controld/` (almost everywhere else), start the system service, and configure the listener on the default network interface. Service will start on OS boot.
 
-In order to stop the service, and restore your DNS to original state, simply run `./ctrld stop`.
+When Control D upstreams are used, `ctrld` willl [relay your network topology](https://docs.controld.com/docs/device-clients) to Control D (LAN IPs, MAC addresses, and hostnames), and you will be able to see your LAN devices in the web panel, view analytics and apply unique profiles to them. 
 
-For granular control of the service, run the `service` command. Each sub-command has its own help section so you can see what arguments you can supply.
+In order to stop the service, and restore your DNS to original state, simply run `./ctrld stop`. If you wish to stop and uninstall the service permanently, run `./ctrld uninstall`. 
 
-```
-  Manage ctrld service
 
-  Usage:
+### Supported Routers
-    ctrld service [command]
+You can run `ctrld` on any supported router, which will function similarly to the Service Mode mentioned above. The list of supported routers and firmware includes:
+- Asus Merlin
+- DD-WRT
+- Firewalla
+- FreshTomato
+- GL.iNet
+- OpenWRT
+- pfSense / OPNsense
+- Synology 
+- Ubiquiti (UniFi, EdgeOS)
 
-  Available Commands:
+`ctrld` will attempt to interface with dnsmasq whenever possible and set itself as the upstream, while running on port 5354. On FreeBSD based OSes, `ctrld` will terminate dnsmasq and unbound in order to be able to listen on port 53 directly.  
-    interfaces  Manage network interfaces
-    restart     Restart the ctrld service
-    start       Start the ctrld service
-    status      Show status of the ctrld service
-    stop        Stop the ctrld service
-    uninstall   Uninstall the ctrld service
 
-  Flags:
-    -h, --help   help for service
-
-  Global Flags:
-    -v, --verbose count   verbose log output, "-v" basic logging, "-vv" debug level logging
-
-  Use "ctrld service [command] --help" for more information about a command.
-```
 
 ### Control D Auto Configuration
-Application can be started with a specific resolver config, instead of the default one. Simply supply your resolver ID with a `--cd` flag, when using the `run` (foreground) or `start` (service) modes. 
+Application can be started with a specific resolver config, instead of the default one. Simply supply your Resolver ID with a `--cd` flag, when using the `run` (foreground) or `start` (service) modes. 
 
 The following command will start the application in foreground mode, using the free "p2" resolver, which blocks Ads & Trackers. 
 
@@ -126,22 +163,22 @@ The following command will start the application in foreground mode, using the f
 ./ctrld run --cd p2
 ```
 
-Alternatively, you can use your own personal Control D Device resolver, and start the application in service mode. Your resolver ID is the part after the slash of your DNS-over-HTTPS resolver. ie. https://dns.controld.com/abcd1234
+Alternatively, you can use your own personal Control D Device resolver, and start the application in service mode. Your resolver ID is displayed on the "Show Resolvers" screen for the relevant Control D Device. 
 
 ```shell
 ./ctrld start --cd abcd1234
 ```
 
-Once you run the above command, the following things will happen:
+Once you run the above commands (in service mode only), the following things will happen:
 - You resolver configuration will be fetched from the API, and config file templated with the resolver data
-- Application will start as a service, and keep running (even after reboot) until you run the `stop` or `service uninstall` sub-commands
+- Application will start as a service, and keep running (even after reboot) until you run the `stop` or `uninstall` sub-commands
 - Your default network interface will be updated to use the listener started by the service
 - All OS DNS queries will be sent to the listener
 
-## Configuration
+# Configuration
 See [Configuration Docs](docs/config.md).
 
-### Example 
+## Example 
 - Start `listener.0` on 127.0.0.1:53
 - Accept queries from any source address
 - Send all queries to `upstream.0` via DoH protocol
@@ -183,17 +220,17 @@ See [Configuration Docs](docs/config.md).
 
 ```
 
-### Advanced
+## Advanced Configuration
 The above is the most basic example, which will work out of the box. If you're looking to do advanced configurations using policies, see [Configuration Docs](docs/config.md) for complete documentation of the config file.
 
 You can also supply configuration via launch argeuments, in [Ephemeral Mode](docs/ephemeral_mode.md).
 
 ## Contributing
-
 See [Contribution Guideline](./docs/contributing.md)
 
 ## Roadmap
 The following functionality is on the roadmap and will be available in future releases. 
-- Router self-installation
-- Client hostname/MAC passthrough
 - Prometheus metrics exporter 
+- DNS intercept mode
+- Direct listener mode
+- Support for more routers (let us know which ones)

client_info.go

@@ -0,0 +1,19 @@
+package ctrld
+
+// ClientInfoCtxKey is the context key to store client info.
+type ClientInfoCtxKey struct{}
+
+// ClientInfo represents ctrld's clients information.
+type ClientInfo struct {
+	Mac      string
+	IP       string
+	Hostname string
+}
+
+// LeaseFileFormat specifies the format of DHCP lease file.
+type LeaseFileFormat string
+
+const (
+	Dnsmasq  LeaseFileFormat = "dnsmasq"
+	IscDhcpd LeaseFileFormat = "isc-dhcpd"
+)

cmd/cli/cli_test.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"os"

cmd/cli/conn.go

@@ -0,0 +1,51 @@
+package cli
+
+import (
+	"net"
+	"time"
+)
+
+// logConn wraps a net.Conn, override the Write behavior.
+// runCmd uses this wrapper, so as long as startCmd finished,
+// ctrld log won't be flushed with un-necessary write errors.
+type logConn struct {
+	conn net.Conn
+}
+
+func (lc *logConn) Read(b []byte) (n int, err error) {
+	return lc.conn.Read(b)
+}
+
+func (lc *logConn) Close() error {
+	return lc.conn.Close()
+}
+
+func (lc *logConn) LocalAddr() net.Addr {
+	return lc.conn.LocalAddr()
+}
+
+func (lc *logConn) RemoteAddr() net.Addr {
+	return lc.conn.RemoteAddr()
+}
+
+func (lc *logConn) SetDeadline(t time.Time) error {
+	return lc.conn.SetDeadline(t)
+}
+
+func (lc *logConn) SetReadDeadline(t time.Time) error {
+	return lc.conn.SetReadDeadline(t)
+}
+
+func (lc *logConn) SetWriteDeadline(t time.Time) error {
+	return lc.conn.SetWriteDeadline(t)
+}
+
+func (lc *logConn) Write(b []byte) (int, error) {
+	// Write performs writes with underlying net.Conn, ignore any errors happen.
+	// "ctrld run" command use this wrapper to report errors to "ctrld start".
+	// If no error occurred, "ctrld start" may finish before "ctrld run" attempt
+	// to close the connection, so ignore errors conservatively here, prevent
+	// un-necessary error "write to closed connection" flushed to ctrld log.
+	_, _ = lc.conn.Write(b)
+	return len(b), nil
+}

cmd/cli/control_client.go

@@ -0,0 +1,29 @@
+package cli
+
+import (
+	"context"
+	"io"
+	"net"
+	"net/http"
+	"time"
+)
+
+type controlClient struct {
+	c *http.Client
+}
+
+func newControlClient(addr string) *controlClient {
+	return &controlClient{c: &http.Client{
+		Transport: &http.Transport{
+			DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
+				d := net.Dialer{}
+				return d.DialContext(ctx, "unix", addr)
+			},
+		},
+		Timeout: time.Second * 30,
+	}}
+}
+
+func (c *controlClient) post(path string, data io.Reader) (*http.Response, error) {
+	return c.c.Post("http://unix"+path, contentTypeJson, data)
+}

cmd/cli/control_server.go

@@ -0,0 +1,85 @@
+package cli
+
+import (
+	"context"
+	"encoding/json"
+	"net"
+	"net/http"
+	"os"
+	"sort"
+	"time"
+)
+
+const (
+	contentTypeJson = "application/json"
+	listClientsPath = "/clients"
+	startedPath     = "/started"
+)
+
+type controlServer struct {
+	server *http.Server
+	mux    *http.ServeMux
+	addr   string
+}
+
+func newControlServer(addr string) (*controlServer, error) {
+	mux := http.NewServeMux()
+	s := &controlServer{
+		server: &http.Server{Handler: mux},
+		mux:    mux,
+	}
+	s.addr = addr
+	return s, nil
+}
+
+func (s *controlServer) start() error {
+	_ = os.Remove(s.addr)
+	unixListener, err := net.Listen("unix", s.addr)
+	if l, ok := unixListener.(*net.UnixListener); ok {
+		l.SetUnlinkOnClose(true)
+	}
+	if err != nil {
+		return err
+	}
+	go s.server.Serve(unixListener)
+	return nil
+}
+
+func (s *controlServer) stop() error {
+	_ = os.Remove(s.addr)
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*2)
+	defer cancel()
+	return s.server.Shutdown(ctx)
+}
+
+func (s *controlServer) register(pattern string, handler http.Handler) {
+	s.mux.Handle(pattern, jsonResponse(handler))
+}
+
+func (p *prog) registerControlServerHandler() {
+	p.cs.register(listClientsPath, http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
+		clients := p.ciTable.ListClients()
+		sort.Slice(clients, func(i, j int) bool {
+			return clients[i].IP.Less(clients[j].IP)
+		})
+		if err := json.NewEncoder(w).Encode(&clients); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}))
+	p.cs.register(startedPath, http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
+		select {
+		case <-p.onStartedDone:
+			w.WriteHeader(http.StatusOK)
+		case <-time.After(10 * time.Second):
+			w.WriteHeader(http.StatusRequestTimeout)
+		}
+	}))
+}
+
+func jsonResponse(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		next.ServeHTTP(w, r)
+	})
+}

cmd/cli/control_server_test.go

@@ -0,0 +1,54 @@
+package cli
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"os"
+	"testing"
+)
+
+func TestControlServer(t *testing.T) {
+	f, err := os.CreateTemp("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(f.Name())
+	f.Close()
+
+	s, err := newControlServer(f.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+	pattern := "/ping"
+	respBody := []byte("pong")
+	s.register(pattern, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write(respBody)
+	}))
+	if err := s.start(); err != nil {
+		t.Fatal(err)
+	}
+
+	c := newControlClient(f.Name())
+	resp, err := c.post(pattern, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Fatalf("unepxected response code: %d", resp.StatusCode)
+	}
+	if ct := resp.Header.Get("content-type"); ct != contentTypeJson {
+		t.Fatalf("unexpected content type: %s", ct)
+	}
+	buf, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(buf, respBody) {
+		t.Errorf("unexpected response body, want: %q, got: %q", string(respBody), string(buf))
+	}
+	if err := s.stop(); err != nil {
+		t.Fatal(err)
+	}
+}

cmd/cli/dns.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 //lint:ignore U1000 use in os_linux.go
 type getDNS func(iface string) []string

cmd/cli/dns_proxy.go

@@ -0,0 +1,569 @@
+package cli
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"net"
+	"net/netip"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/miekg/dns"
+	"go4.org/mem"
+	"golang.org/x/sync/errgroup"
+	"tailscale.com/net/interfaces"
+	"tailscale.com/util/lineread"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/dnscache"
+	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
+)
+
+const (
+	staleTTL = 60 * time.Second
+	// EDNS0_OPTION_MAC is dnsmasq EDNS0 code for adding mac option.
+	// https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=blob;f=src/dns-protocol.h;h=76ac66a8c28317e9c121a74ab5fd0e20f6237dc8;hb=HEAD#l81
+	// This is also dns.EDNS0LOCALSTART, but define our own constant here for clarification.
+	EDNS0_OPTION_MAC = 0xFDE9
+)
+
+var osUpstreamConfig = &ctrld.UpstreamConfig{
+	Name:    "OS resolver",
+	Type:    ctrld.ResolverTypeOS,
+	Timeout: 2000,
+}
+
+func (p *prog) serveDNS(listenerNum string) error {
+	listenerConfig := p.cfg.Listener[listenerNum]
+	// make sure ip is allocated
+	if allocErr := p.allocateIP(listenerConfig.IP); allocErr != nil {
+		mainLog.Load().Error().Err(allocErr).Str("ip", listenerConfig.IP).Msg("serveUDP: failed to allocate listen ip")
+		return allocErr
+	}
+	var failoverRcodes []int
+	if listenerConfig.Policy != nil {
+		failoverRcodes = listenerConfig.Policy.FailoverRcodeNumbers
+	}
+	handler := dns.HandlerFunc(func(w dns.ResponseWriter, m *dns.Msg) {
+		p.sema.acquire()
+		defer p.sema.release()
+		q := m.Question[0]
+		domain := canonicalName(q.Name)
+		reqId := requestID()
+		remoteIP, _, _ := net.SplitHostPort(w.RemoteAddr().String())
+		mac := macFromMsg(m)
+		ci := p.getClientInfo(remoteIP, mac)
+		remoteAddr := spoofRemoteAddr(w.RemoteAddr(), ci)
+		fmtSrcToDest := fmtRemoteToLocal(listenerNum, remoteAddr.String(), w.LocalAddr().String())
+		t := time.Now()
+		ctx := context.WithValue(context.Background(), ctrld.ReqIdCtxKey{}, reqId)
+		ctrld.Log(ctx, mainLog.Load().Debug(), "%s received query: %s %s", fmtSrcToDest, dns.TypeToString[q.Qtype], domain)
+		upstreams, matched := p.upstreamFor(ctx, listenerNum, listenerConfig, remoteAddr, domain)
+		var answer *dns.Msg
+		if !matched && listenerConfig.Restricted {
+			answer = new(dns.Msg)
+			answer.SetRcode(m, dns.RcodeRefused)
+		} else {
+			answer = p.proxy(ctx, upstreams, failoverRcodes, m, ci)
+			rtt := time.Since(t)
+			ctrld.Log(ctx, mainLog.Load().Debug(), "received response of %d bytes in %s", answer.Len(), rtt)
+		}
+		if err := w.WriteMsg(answer); err != nil {
+			ctrld.Log(ctx, mainLog.Load().Error().Err(err), "serveUDP: failed to send DNS response to client")
+		}
+	})
+
+	g, ctx := errgroup.WithContext(context.Background())
+	for _, proto := range []string{"udp", "tcp"} {
+		proto := proto
+		if needLocalIPv6Listener() {
+			g.Go(func() error {
+				s, errCh := runDNSServer(net.JoinHostPort("::1", strconv.Itoa(listenerConfig.Port)), proto, handler)
+				defer s.Shutdown()
+				select {
+				case <-p.stopCh:
+				case <-ctx.Done():
+				case err := <-errCh:
+					// Local ipv6 listener should not terminate ctrld.
+					// It's a workaround for a quirk on Windows.
+					mainLog.Load().Warn().Err(err).Msg("local ipv6 listener failed")
+				}
+				return nil
+			})
+		}
+		// When we spawn a listener on 127.0.0.1, also spawn listeners on the RFC1918
+		// addresses of the machine. So ctrld could receive queries from LAN clients.
+		if needRFC1918Listeners(listenerConfig) {
+			g.Go(func() error {
+				for _, addr := range rfc1918Addresses() {
+					func() {
+						listenAddr := net.JoinHostPort(addr, strconv.Itoa(listenerConfig.Port))
+						s, errCh := runDNSServer(listenAddr, proto, handler)
+						defer s.Shutdown()
+						select {
+						case <-p.stopCh:
+						case <-ctx.Done():
+						case err := <-errCh:
+							// RFC1918 listener should not terminate ctrld.
+							// It's a workaround for a quirk on system with systemd-resolved.
+							mainLog.Load().Warn().Err(err).Msgf("could not listen on %s: %s", proto, listenAddr)
+						}
+					}()
+				}
+				return nil
+			})
+		}
+		g.Go(func() error {
+			s, errCh := runDNSServer(dnsListenAddress(listenerConfig), proto, handler)
+			defer s.Shutdown()
+			select {
+			case err := <-errCh:
+				return err
+			case <-time.After(5 * time.Second):
+				p.started <- struct{}{}
+			}
+			select {
+			case <-p.stopCh:
+			case <-ctx.Done():
+			case err := <-errCh:
+				return err
+			}
+			return nil
+		})
+	}
+	return g.Wait()
+}
+
+// upstreamFor returns the list of upstreams for resolving the given domain,
+// matching by policies defined in the listener config. The second return value
+// reports whether the domain matches the policy.
+//
+// Though domain policy has higher priority than network policy, it is still
+// processed later, because policy logging want to know whether a network rule
+// is disregarded in favor of the domain level rule.
+func (p *prog) upstreamFor(ctx context.Context, defaultUpstreamNum string, lc *ctrld.ListenerConfig, addr net.Addr, domain string) ([]string, bool) {
+	upstreams := []string{"upstream." + defaultUpstreamNum}
+	matchedPolicy := "no policy"
+	matchedNetwork := "no network"
+	matchedRule := "no rule"
+	matched := false
+
+	defer func() {
+		if !matched && lc.Restricted {
+			ctrld.Log(ctx, mainLog.Load().Info(), "query refused, %s does not match any network policy", addr.String())
+			return
+		}
+		if matched {
+			ctrld.Log(ctx, mainLog.Load().Info(), "%s, %s, %s -> %v", matchedPolicy, matchedNetwork, matchedRule, upstreams)
+		} else {
+			ctrld.Log(ctx, mainLog.Load().Info(), "no explicit policy matched, using default routing -> %v", upstreams)
+		}
+	}()
+
+	if lc.Policy == nil {
+		return upstreams, false
+	}
+
+	do := func(policyUpstreams []string) {
+		upstreams = append([]string(nil), policyUpstreams...)
+	}
+
+	var networkTargets []string
+	var sourceIP net.IP
+	switch addr := addr.(type) {
+	case *net.UDPAddr:
+		sourceIP = addr.IP
+	case *net.TCPAddr:
+		sourceIP = addr.IP
+	}
+
+networkRules:
+	for _, rule := range lc.Policy.Networks {
+		for source, targets := range rule {
+			networkNum := strings.TrimPrefix(source, "network.")
+			nc := p.cfg.Network[networkNum]
+			if nc == nil {
+				continue
+			}
+			for _, ipNet := range nc.IPNets {
+				if ipNet.Contains(sourceIP) {
+					matchedPolicy = lc.Policy.Name
+					matchedNetwork = source
+					networkTargets = targets
+					matched = true
+					break networkRules
+				}
+			}
+		}
+	}
+
+	for _, rule := range lc.Policy.Rules {
+		// There's only one entry per rule, config validation ensures this.
+		for source, targets := range rule {
+			if source == domain || wildcardMatches(source, domain) {
+				matchedPolicy = lc.Policy.Name
+				if len(networkTargets) > 0 {
+					matchedNetwork += " (unenforced)"
+				}
+				matchedRule = source
+				do(targets)
+				matched = true
+				return upstreams, matched
+			}
+		}
+	}
+
+	if matched {
+		do(networkTargets)
+	}
+
+	return upstreams, matched
+}
+
+func (p *prog) proxy(ctx context.Context, upstreams []string, failoverRcodes []int, msg *dns.Msg, ci *ctrld.ClientInfo) *dns.Msg {
+	var staleAnswer *dns.Msg
+	serveStaleCache := p.cache != nil && p.cfg.Service.CacheServeStale
+	upstreamConfigs := p.upstreamConfigsFromUpstreamNumbers(upstreams)
+	if len(upstreamConfigs) == 0 {
+		upstreamConfigs = []*ctrld.UpstreamConfig{osUpstreamConfig}
+		upstreams = []string{"upstream.os"}
+	}
+	// Inverse query should not be cached: https://www.rfc-editor.org/rfc/rfc1035#section-7.4
+	if p.cache != nil && msg.Question[0].Qtype != dns.TypePTR {
+		for _, upstream := range upstreams {
+			cachedValue := p.cache.Get(dnscache.NewKey(msg, upstream))
+			if cachedValue == nil {
+				continue
+			}
+			answer := cachedValue.Msg.Copy()
+			answer.SetRcode(msg, answer.Rcode)
+			now := time.Now()
+			if cachedValue.Expire.After(now) {
+				ctrld.Log(ctx, mainLog.Load().Debug(), "hit cached response")
+				setCachedAnswerTTL(answer, now, cachedValue.Expire)
+				return answer
+			}
+			staleAnswer = answer
+		}
+	}
+	resolve1 := func(n int, upstreamConfig *ctrld.UpstreamConfig, msg *dns.Msg) (*dns.Msg, error) {
+		ctrld.Log(ctx, mainLog.Load().Debug(), "sending query to %s: %s", upstreams[n], upstreamConfig.Name)
+		dnsResolver, err := ctrld.NewResolver(upstreamConfig)
+		if err != nil {
+			ctrld.Log(ctx, mainLog.Load().Error().Err(err), "failed to create resolver")
+			return nil, err
+		}
+		resolveCtx, cancel := context.WithCancel(ctx)
+		defer cancel()
+		if upstreamConfig.Timeout > 0 {
+			timeoutCtx, cancel := context.WithTimeout(resolveCtx, time.Millisecond*time.Duration(upstreamConfig.Timeout))
+			defer cancel()
+			resolveCtx = timeoutCtx
+		}
+		return dnsResolver.Resolve(resolveCtx, msg)
+	}
+	resolve := func(n int, upstreamConfig *ctrld.UpstreamConfig, msg *dns.Msg) *dns.Msg {
+		if upstreamConfig.UpstreamSendClientInfo() && ci != nil {
+			ctrld.Log(ctx, mainLog.Load().Debug(), "including client info with the request")
+			ctx = context.WithValue(ctx, ctrld.ClientInfoCtxKey{}, ci)
+		}
+		answer, err := resolve1(n, upstreamConfig, msg)
+		if err != nil {
+			ctrld.Log(ctx, mainLog.Load().Error().Err(err), "failed to resolve query")
+			return nil
+		}
+		return answer
+	}
+	for n, upstreamConfig := range upstreamConfigs {
+		if upstreamConfig == nil {
+			continue
+		}
+		answer := resolve(n, upstreamConfig, msg)
+		if answer == nil {
+			if serveStaleCache && staleAnswer != nil {
+				ctrld.Log(ctx, mainLog.Load().Debug(), "serving stale cached response")
+				now := time.Now()
+				setCachedAnswerTTL(staleAnswer, now, now.Add(staleTTL))
+				return staleAnswer
+			}
+			continue
+		}
+		if answer.Rcode != dns.RcodeSuccess && len(upstreamConfigs) > 1 && containRcode(failoverRcodes, answer.Rcode) {
+			ctrld.Log(ctx, mainLog.Load().Debug(), "failover rcode matched, process to next upstream")
+			continue
+		}
+
+		// set compression, as it is not set by default when unpacking
+		answer.Compress = true
+
+		if p.cache != nil {
+			ttl := ttlFromMsg(answer)
+			now := time.Now()
+			expired := now.Add(time.Duration(ttl) * time.Second)
+			if cachedTTL := p.cfg.Service.CacheTTLOverride; cachedTTL > 0 {
+				expired = now.Add(time.Duration(cachedTTL) * time.Second)
+			}
+			setCachedAnswerTTL(answer, now, expired)
+			p.cache.Add(dnscache.NewKey(msg, upstreams[n]), dnscache.NewValue(answer, expired))
+			ctrld.Log(ctx, mainLog.Load().Debug(), "add cached response")
+		}
+		return answer
+	}
+	ctrld.Log(ctx, mainLog.Load().Error(), "all upstreams failed")
+	answer := new(dns.Msg)
+	answer.SetRcode(msg, dns.RcodeServerFailure)
+	return answer
+}
+
+func (p *prog) upstreamConfigsFromUpstreamNumbers(upstreams []string) []*ctrld.UpstreamConfig {
+	upstreamConfigs := make([]*ctrld.UpstreamConfig, 0, len(upstreams))
+	for _, upstream := range upstreams {
+		upstreamNum := strings.TrimPrefix(upstream, "upstream.")
+		upstreamConfigs = append(upstreamConfigs, p.cfg.Upstream[upstreamNum])
+	}
+	return upstreamConfigs
+}
+
+// canonicalName returns canonical name from FQDN with "." trimmed.
+func canonicalName(fqdn string) string {
+	q := strings.TrimSpace(fqdn)
+	q = strings.TrimSuffix(q, ".")
+	// https://datatracker.ietf.org/doc/html/rfc4343
+	q = strings.ToLower(q)
+
+	return q
+}
+
+func wildcardMatches(wildcard, domain string) bool {
+	// Wildcard match.
+	wildCardParts := strings.Split(wildcard, "*")
+	if len(wildCardParts) != 2 {
+		return false
+	}
+
+	switch {
+	case len(wildCardParts[0]) > 0 && len(wildCardParts[1]) > 0:
+		// Domain must match both prefix and suffix.
+		return strings.HasPrefix(domain, wildCardParts[0]) && strings.HasSuffix(domain, wildCardParts[1])
+
+	case len(wildCardParts[1]) > 0:
+		// Only suffix must match.
+		return strings.HasSuffix(domain, wildCardParts[1])
+
+	case len(wildCardParts[0]) > 0:
+		// Only prefix must match.
+		return strings.HasPrefix(domain, wildCardParts[0])
+	}
+
+	return false
+}
+
+func fmtRemoteToLocal(listenerNum, remote, local string) string {
+	return fmt.Sprintf("%s -> listener.%s: %s:", remote, listenerNum, local)
+}
+
+func requestID() string {
+	b := make([]byte, 3) // 6 chars
+	if _, err := rand.Read(b); err != nil {
+		panic(err)
+	}
+	return hex.EncodeToString(b)
+}
+
+func containRcode(rcodes []int, rcode int) bool {
+	for i := range rcodes {
+		if rcodes[i] == rcode {
+			return true
+		}
+	}
+	return false
+}
+
+func setCachedAnswerTTL(answer *dns.Msg, now, expiredTime time.Time) {
+	ttlSecs := expiredTime.Sub(now).Seconds()
+	if ttlSecs < 0 {
+		return
+	}
+
+	ttl := uint32(ttlSecs)
+	for _, rr := range answer.Answer {
+		rr.Header().Ttl = ttl
+	}
+	for _, rr := range answer.Ns {
+		rr.Header().Ttl = ttl
+	}
+	for _, rr := range answer.Extra {
+		if rr.Header().Rrtype != dns.TypeOPT {
+			rr.Header().Ttl = ttl
+		}
+	}
+}
+
+func ttlFromMsg(msg *dns.Msg) uint32 {
+	for _, rr := range msg.Answer {
+		return rr.Header().Ttl
+	}
+	for _, rr := range msg.Ns {
+		return rr.Header().Ttl
+	}
+	return 0
+}
+
+func needLocalIPv6Listener() bool {
+	// On Windows, there's no easy way for disabling/removing IPv6 DNS resolver, so we check whether we can
+	// listen on ::1, then spawn a listener for receiving DNS requests.
+	return ctrldnet.SupportsIPv6ListenLocal() && runtime.GOOS == "windows"
+}
+
+func dnsListenAddress(lc *ctrld.ListenerConfig) string {
+	// If we are inside container and the listener loopback address, change
+	// the address to something like 0.0.0.0:53, so user can expose the port to outside.
+	if inContainer() {
+		if ip := net.ParseIP(lc.IP); ip != nil && ip.IsLoopback() {
+			return net.JoinHostPort("0.0.0.0", strconv.Itoa(lc.Port))
+		}
+	}
+	return net.JoinHostPort(lc.IP, strconv.Itoa(lc.Port))
+}
+
+func macFromMsg(msg *dns.Msg) string {
+	if opt := msg.IsEdns0(); opt != nil {
+		for _, s := range opt.Option {
+			switch e := s.(type) {
+			case *dns.EDNS0_LOCAL:
+				if e.Code == EDNS0_OPTION_MAC {
+					return net.HardwareAddr(e.Data).String()
+				}
+			}
+		}
+	}
+	return ""
+}
+
+func spoofRemoteAddr(addr net.Addr, ci *ctrld.ClientInfo) net.Addr {
+	if ci != nil && ci.IP != "" {
+		switch addr := addr.(type) {
+		case *net.UDPAddr:
+			udpAddr := &net.UDPAddr{
+				IP:   net.ParseIP(ci.IP),
+				Port: addr.Port,
+				Zone: addr.Zone,
+			}
+			return udpAddr
+		case *net.TCPAddr:
+			udpAddr := &net.TCPAddr{
+				IP:   net.ParseIP(ci.IP),
+				Port: addr.Port,
+				Zone: addr.Zone,
+			}
+			return udpAddr
+		}
+	}
+	return addr
+}
+
+// runDNSServer starts a DNS server for given address and network,
+// with the given handler. It ensures the server has started listening.
+// Any error will be reported to the caller via returned channel.
+//
+// It's the caller responsibility to call Shutdown to close the server.
+func runDNSServer(addr, network string, handler dns.Handler) (*dns.Server, <-chan error) {
+	s := &dns.Server{
+		Addr:    addr,
+		Net:     network,
+		Handler: handler,
+	}
+
+	waitLock := sync.Mutex{}
+	waitLock.Lock()
+	s.NotifyStartedFunc = waitLock.Unlock
+
+	errCh := make(chan error)
+	go func() {
+		defer close(errCh)
+		if err := s.ListenAndServe(); err != nil {
+			waitLock.Unlock()
+			mainLog.Load().Error().Err(err).Msgf("could not listen and serve on: %s", s.Addr)
+			errCh <- err
+		}
+	}()
+	waitLock.Lock()
+	return s, errCh
+}
+
+// inContainer reports whether we're running in a container.
+//
+// Copied from https://github.com/tailscale/tailscale/blob/v1.42.0/hostinfo/hostinfo.go#L260
+// with modification for ctrld usage.
+func inContainer() bool {
+	if runtime.GOOS != "linux" {
+		return false
+	}
+
+	var ret bool
+	if _, err := os.Stat("/.dockerenv"); err == nil {
+		return true
+	}
+	if _, err := os.Stat("/run/.containerenv"); err == nil {
+		// See https://github.com/cri-o/cri-o/issues/5461
+		return true
+	}
+	lineread.File("/proc/1/cgroup", func(line []byte) error {
+		if mem.Contains(mem.B(line), mem.S("/docker/")) ||
+			mem.Contains(mem.B(line), mem.S("/lxc/")) {
+			ret = true
+			return io.EOF // arbitrary non-nil error to stop loop
+		}
+		return nil
+	})
+	lineread.File("/proc/mounts", func(line []byte) error {
+		if mem.Contains(mem.B(line), mem.S("lxcfs /proc/cpuinfo fuse.lxcfs")) {
+			ret = true
+			return io.EOF
+		}
+		return nil
+	})
+	return ret
+}
+
+func (p *prog) getClientInfo(ip, mac string) *ctrld.ClientInfo {
+	ci := &ctrld.ClientInfo{}
+	if mac != "" {
+		ci.Mac = mac
+		ci.IP = p.ciTable.LookupIP(mac)
+	} else {
+		ci.IP = ip
+		ci.Mac = p.ciTable.LookupMac(ip)
+		if ip == "127.0.0.1" || ip == "::1" {
+			ci.IP = p.ciTable.LookupIP(ci.Mac)
+		}
+	}
+	ci.Hostname = p.ciTable.LookupHostname(ci.IP, ci.Mac)
+	return ci
+}
+
+func needRFC1918Listeners(lc *ctrld.ListenerConfig) bool {
+	return lc.IP == "127.0.0.1" && lc.Port == 53
+}
+
+func rfc1918Addresses() []string {
+	var res []string
+	interfaces.ForeachInterface(func(i interfaces.Interface, prefixes []netip.Prefix) {
+		addrs, _ := i.Addrs()
+		for _, addr := range addrs {
+			ipNet, ok := addr.(*net.IPNet)
+			if !ok || !ipNet.IP.IsPrivate() {
+				continue
+			}
+			res = append(res, ipNet.IP.String())
+		}
+	})
+	return res
+}

cmd/cli/dns_proxy_test.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"context"
@@ -86,17 +86,17 @@ func Test_prog_upstreamFor(t *testing.T) {
 		domain             string
 		upstreams          []string
 		matched            bool
+		testLogMsg         string
 	}{
-		{"Policy map matches", "192.168.0.1:0", "0", prog.cfg.Listener["0"], "abc.xyz", []string{"upstream.1", "upstream.0"}, true},
+		{"Policy map matches", "192.168.0.1:0", "0", prog.cfg.Listener["0"], "abc.xyz", []string{"upstream.1", "upstream.0"}, true, ""},
-		{"Policy split matches", "192.168.0.1:0", "0", prog.cfg.Listener["0"], "abc.ru", []string{"upstream.1"}, true},
+		{"Policy split matches", "192.168.0.1:0", "0", prog.cfg.Listener["0"], "abc.ru", []string{"upstream.1"}, true, ""},
-		{"Policy map for other network matches", "192.168.1.2:0", "0", prog.cfg.Listener["0"], "abc.xyz", []string{"upstream.0"}, true},
+		{"Policy map for other network matches", "192.168.1.2:0", "0", prog.cfg.Listener["0"], "abc.xyz", []string{"upstream.0"}, true, ""},
-		{"No policy map for listener", "192.168.1.2:0", "1", prog.cfg.Listener["1"], "abc.ru", []string{"upstream.1"}, false},
+		{"No policy map for listener", "192.168.1.2:0", "1", prog.cfg.Listener["1"], "abc.ru", []string{"upstream.1"}, false, ""},
+		{"unenforced loging", "192.168.1.2:0", "0", prog.cfg.Listener["0"], "abc.ru", []string{"upstream.1"}, true, "My Policy, network.1 (unenforced), *.ru -> [upstream.1]"},
 	}
 
 	for _, tc := range tests {
-		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
 			for _, network := range []string{"udp", "tcp"} {
 				var (
 					addr net.Addr
@@ -114,6 +114,9 @@ func Test_prog_upstreamFor(t *testing.T) {
 				upstreams, matched := prog.upstreamFor(ctx, tc.defaultUpstreamNum, tc.lc, addr, tc.domain)
 				assert.Equal(t, tc.matched, matched)
 				assert.Equal(t, tc.upstreams, upstreams)
+				if tc.testLogMsg != "" {
+					assert.Contains(t, logOutput.String(), tc.testLogMsg)
+				}
 			}
 		})
 	}
@@ -146,9 +149,70 @@ func TestCache(t *testing.T) {
 	answer2.SetRcode(msg, dns.RcodeRefused)
 	prog.cache.Add(dnscache.NewKey(msg, "upstream.0"), dnscache.NewValue(answer2, time.Now().Add(time.Minute)))
 
-	got1 := prog.proxy(context.Background(), []string{"upstream.1"}, nil, msg)
+	got1 := prog.proxy(context.Background(), []string{"upstream.1"}, nil, msg, nil)
-	got2 := prog.proxy(context.Background(), []string{"upstream.0"}, nil, msg)
+	got2 := prog.proxy(context.Background(), []string{"upstream.0"}, nil, msg, nil)
 	assert.NotSame(t, got1, got2)
 	assert.Equal(t, answer1.Rcode, got1.Rcode)
 	assert.Equal(t, answer2.Rcode, got2.Rcode)
 }
+
+func Test_macFromMsg(t *testing.T) {
+	tests := []struct {
+		name    string
+		mac     string
+		wantMac bool
+	}{
+		{"has mac", "4c:20:b8:ab:87:1b", true},
+		{"no mac", "4c:20:b8:ab:87:1b", false},
+	}
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			hw, err := net.ParseMAC(tc.mac)
+			if err != nil {
+				t.Fatal(err)
+			}
+			m := new(dns.Msg)
+			m.SetQuestion("example.com.", dns.TypeA)
+			o := &dns.OPT{Hdr: dns.RR_Header{Name: ".", Rrtype: dns.TypeOPT}}
+			if tc.wantMac {
+				ec1 := &dns.EDNS0_LOCAL{Code: EDNS0_OPTION_MAC, Data: hw}
+				o.Option = append(o.Option, ec1)
+			}
+			m.Extra = append(m.Extra, o)
+			got := macFromMsg(m)
+			if tc.wantMac && got != tc.mac {
+				t.Errorf("mismatch, want: %q, got: %q", tc.mac, got)
+			}
+			if !tc.wantMac && got != "" {
+				t.Errorf("unexpected mac: %q", got)
+			}
+		})
+	}
+}
+
+func Test_remoteAddrFromMsg(t *testing.T) {
+	loopbackIP := net.ParseIP("127.0.0.1")
+	tests := []struct {
+		name string
+		addr net.Addr
+		ci   *ctrld.ClientInfo
+		want string
+	}{
+		{"tcp", &net.TCPAddr{IP: loopbackIP, Port: 12345}, &ctrld.ClientInfo{IP: "192.168.1.10"}, "192.168.1.10:12345"},
+		{"udp", &net.UDPAddr{IP: loopbackIP, Port: 12345}, &ctrld.ClientInfo{IP: "192.168.1.11"}, "192.168.1.11:12345"},
+		{"nil client info", &net.UDPAddr{IP: loopbackIP, Port: 12345}, nil, "127.0.0.1:12345"},
+		{"empty ip", &net.UDPAddr{IP: loopbackIP, Port: 12345}, &ctrld.ClientInfo{}, "127.0.0.1:12345"},
+	}
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			addr := spoofRemoteAddr(tc.addr, tc.ci)
+			if addr.String() != tc.want {
+				t.Errorf("unexpected result, want: %q, got: %q", tc.want, addr.String())
+			}
+		})
+	}
+}

cmd/cli/main.go

@@ -0,0 +1,161 @@
+package cli
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"sync/atomic"
+	"time"
+
+	"github.com/kardianos/service"
+	"github.com/rs/zerolog"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+var (
+	configPath        string
+	configBase64      string
+	daemon            bool
+	listenAddress     string
+	primaryUpstream   string
+	secondaryUpstream string
+	domains           []string
+	logPath           string
+	homedir           string
+	cacheSize         int
+	cfg               ctrld.Config
+	verbose           int
+	silent            bool
+	cdUID             string
+	cdOrg             string
+	cdDev             bool
+	iface             string
+	ifaceStartStop    string
+
+	mainLog       atomic.Pointer[zerolog.Logger]
+	consoleWriter zerolog.ConsoleWriter
+)
+
+func init() {
+	l := zerolog.New(io.Discard)
+	mainLog.Store(&l)
+}
+
+func Main() {
+	ctrld.InitConfig(v, "ctrld")
+	initCLI()
+	if err := rootCmd.Execute(); err != nil {
+		mainLog.Load().Error().Msg(err.Error())
+		os.Exit(1)
+	}
+}
+
+func normalizeLogFilePath(logFilePath string) string {
+	if logFilePath == "" || filepath.IsAbs(logFilePath) || service.Interactive() {
+		return logFilePath
+	}
+	if homedir != "" {
+		return filepath.Join(homedir, logFilePath)
+	}
+	dir, _ := userHomeDir()
+	if dir == "" {
+		return logFilePath
+	}
+	return filepath.Join(dir, logFilePath)
+}
+
+func initConsoleLogging() {
+	consoleWriter = zerolog.NewConsoleWriter(func(w *zerolog.ConsoleWriter) {
+		w.TimeFormat = time.StampMilli
+	})
+	multi := zerolog.MultiLevelWriter(consoleWriter)
+	l := mainLog.Load().Output(multi).With().Timestamp().Logger()
+	mainLog.Store(&l)
+	switch {
+	case silent:
+		zerolog.SetGlobalLevel(zerolog.NoLevel)
+	case verbose == 1:
+		zerolog.SetGlobalLevel(zerolog.InfoLevel)
+	case verbose > 1:
+		zerolog.SetGlobalLevel(zerolog.DebugLevel)
+	default:
+		zerolog.SetGlobalLevel(zerolog.NoticeLevel)
+	}
+}
+
+// initLogging initializes global logging setup.
+func initLogging() {
+	initLoggingWithBackup(true)
+}
+
+// initLoggingWithBackup initializes log setup base on current config.
+// If doBackup is true, backup old log file with ".1" suffix.
+//
+// This is only used in runCmd for special handling in case of logging config
+// change in cd mode. Without special reason, the caller should use initLogging
+// wrapper instead of calling this function directly.
+func initLoggingWithBackup(doBackup bool) {
+	writers := []io.Writer{io.Discard}
+	if logFilePath := normalizeLogFilePath(cfg.Service.LogPath); logFilePath != "" {
+		// Create parent directory if necessary.
+		if err := os.MkdirAll(filepath.Dir(logFilePath), 0750); err != nil {
+			mainLog.Load().Error().Msgf("failed to create log path: %v", err)
+			os.Exit(1)
+		}
+
+		// Default open log file in append mode.
+		flags := os.O_CREATE | os.O_RDWR | os.O_APPEND
+		if doBackup {
+			// Backup old log file with .1 suffix.
+			if err := os.Rename(logFilePath, logFilePath+".1"); err != nil && !os.IsNotExist(err) {
+				mainLog.Load().Error().Msgf("could not backup old log file: %v", err)
+			} else {
+				// Backup was created, set flags for truncating old log file.
+				flags = os.O_CREATE | os.O_RDWR
+			}
+		}
+		logFile, err := os.OpenFile(logFilePath, flags, os.FileMode(0o600))
+		if err != nil {
+			mainLog.Load().Error().Msgf("failed to create log file: %v", err)
+			os.Exit(1)
+		}
+		writers = append(writers, logFile)
+	}
+	writers = append(writers, consoleWriter)
+	multi := zerolog.MultiLevelWriter(writers...)
+	l := mainLog.Load().Output(multi).With().Timestamp().Logger()
+	mainLog.Store(&l)
+	// TODO: find a better way.
+	ctrld.ProxyLogger.Store(&l)
+
+	zerolog.SetGlobalLevel(zerolog.NoticeLevel)
+	logLevel := cfg.Service.LogLevel
+	switch {
+	case silent:
+		zerolog.SetGlobalLevel(zerolog.NoLevel)
+		return
+	case verbose == 1:
+		logLevel = "info"
+	case verbose > 1:
+		logLevel = "debug"
+	}
+	if logLevel == "" {
+		return
+	}
+	level, err := zerolog.ParseLevel(logLevel)
+	if err != nil {
+		mainLog.Load().Warn().Err(err).Msg("could not set log level")
+		return
+	}
+	zerolog.SetGlobalLevel(level)
+}
+
+func initCache() {
+	if !cfg.Service.CacheEnable {
+		return
+	}
+	if cfg.Service.CacheSize == 0 {
+		cfg.Service.CacheSize = 4096
+	}
+}

cmd/cli/main_test.go

@@ -0,0 +1,17 @@
+package cli
+
+import (
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/rs/zerolog"
+)
+
+var logOutput strings.Builder
+
+func TestMain(m *testing.M) {
+	l := zerolog.New(&logOutput)
+	mainLog.Store(&l)
+	os.Exit(m.Run())
+}

cmd/cli/net_darwin.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"bufio"
@@ -17,7 +17,7 @@ func patchNetIfaceName(iface *net.Interface) error {
 
 	if name := networkServiceName(iface.Name, bytes.NewReader(b)); name != "" {
 		iface.Name = name
-		mainLog.Debug().Str("network_service", name).Msg("found network service name for interface")
+		mainLog.Load().Debug().Str("network_service", name).Msg("found network service name for interface")
 	}
 	return nil
 }

cmd/cli/net_darwin_test.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"strings"

cmd/cli/net_others.go

@@ -1,6 +1,6 @@
 //go:build !darwin
 
-package main
+package cli
 
 import "net"
 

cmd/cli/netlink_linux.go

@@ -0,0 +1,27 @@
+package cli
+
+import (
+	"github.com/vishvananda/netlink"
+	"golang.org/x/sys/unix"
+)
+
+func (p *prog) watchLinkState() {
+	ch := make(chan netlink.LinkUpdate)
+	done := make(chan struct{})
+	defer close(done)
+	if err := netlink.LinkSubscribe(ch, done); err != nil {
+		mainLog.Load().Warn().Err(err).Msg("could not subscribe link")
+		return
+	}
+	for lu := range ch {
+		if lu.Change == 0xFFFFFFFF {
+			continue
+		}
+		if lu.Change&unix.IFF_UP != 0 {
+			mainLog.Load().Debug().Msgf("link state changed, re-bootstrapping")
+			for _, uc := range p.cfg.Upstream {
+				uc.ReBootstrap()
+			}
+		}
+	}
+}

cmd/cli/netlink_others.go

@@ -0,0 +1,5 @@
+//go:build !linux
+
+package cli
+
+func (p *prog) watchLinkState() {}

cmd/cli/network_manager_linux.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"context"
@@ -24,37 +24,37 @@ var networkManagerCtrldConfFile = filepath.Join(nmConfDir, nmCtrldConfFilename)
 
 func setupNetworkManager() error {
 	if content, _ := os.ReadFile(nmCtrldConfContent); string(content) == nmCtrldConfContent {
-		mainLog.Debug().Msg("NetworkManager already setup, nothing to do")
+		mainLog.Load().Debug().Msg("NetworkManager already setup, nothing to do")
 		return nil
 	}
 	err := os.WriteFile(networkManagerCtrldConfFile, []byte(nmCtrldConfContent), os.FileMode(0644))
 	if os.IsNotExist(err) {
-		mainLog.Debug().Msg("NetworkManager is not available")
+		mainLog.Load().Debug().Msg("NetworkManager is not available")
 		return nil
 	}
 	if err != nil {
-		mainLog.Debug().Err(err).Msg("could not write NetworkManager ctrld config file")
+		mainLog.Load().Debug().Err(err).Msg("could not write NetworkManager ctrld config file")
 		return err
 	}
 
 	reloadNetworkManager()
-	mainLog.Debug().Msg("setup NetworkManager done")
+	mainLog.Load().Debug().Msg("setup NetworkManager done")
 	return nil
 }
 
 func restoreNetworkManager() error {
 	err := os.Remove(networkManagerCtrldConfFile)
 	if os.IsNotExist(err) {
-		mainLog.Debug().Msg("NetworkManager is not available")
+		mainLog.Load().Debug().Msg("NetworkManager is not available")
 		return nil
 	}
 	if err != nil {
-		mainLog.Debug().Err(err).Msg("could not remove NetworkManager ctrld config file")
+		mainLog.Load().Debug().Err(err).Msg("could not remove NetworkManager ctrld config file")
 		return err
 	}
 
 	reloadNetworkManager()
-	mainLog.Debug().Msg("restore NetworkManager done")
+	mainLog.Load().Debug().Msg("restore NetworkManager done")
 	return nil
 }
 
@@ -63,14 +63,14 @@ func reloadNetworkManager() {
 	defer cancel()
 	conn, err := dbus.NewSystemConnectionContext(ctx)
 	if err != nil {
-		mainLog.Error().Err(err).Msg("could not create new system connection")
+		mainLog.Load().Error().Err(err).Msg("could not create new system connection")
 		return
 	}
 	defer conn.Close()
 
 	waitCh := make(chan string)
 	if _, err := conn.ReloadUnitContext(ctx, nmSystemdUnitName, "ignore-dependencies", waitCh); err != nil {
-		mainLog.Debug().Err(err).Msg("could not reload NetworkManager")
+		mainLog.Load().Debug().Err(err).Msg("could not reload NetworkManager")
 	}
 	<-waitCh
 }

cmd/cli/network_manager_others.go

@@ -1,6 +1,6 @@
 //go:build !linux
 
-package main
+package cli
 
 func setupNetworkManager() error {
 	reloadNetworkManager()

cmd/cli/os_darwin.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"net"
@@ -12,7 +12,7 @@ import (
 func allocateIP(ip string) error {
 	cmd := exec.Command("ifconfig", "lo0", "alias", ip, "up")
 	if err := cmd.Run(); err != nil {
-		mainLog.Error().Err(err).Msg("allocateIP failed")
+		mainLog.Load().Error().Err(err).Msg("allocateIP failed")
 		return err
 	}
 	return nil
@@ -21,7 +21,7 @@ func allocateIP(ip string) error {
 func deAllocateIP(ip string) error {
 	cmd := exec.Command("ifconfig", "lo0", "-alias", ip)
 	if err := cmd.Run(); err != nil {
-		mainLog.Error().Err(err).Msg("deAllocateIP failed")
+		mainLog.Load().Error().Err(err).Msg("deAllocateIP failed")
 		return err
 	}
 	return nil
@@ -36,7 +36,7 @@ func setDNS(iface *net.Interface, nameservers []string) error {
 	args = append(args, nameservers...)
 
 	if err := exec.Command(cmd, args...).Run(); err != nil {
-		mainLog.Error().Err(err).Msgf("setDNS failed, ips = %q", nameservers)
+		mainLog.Load().Error().Err(err).Msgf("setDNS failed, ips = %q", nameservers)
 		return err
 	}
 	return nil
@@ -48,7 +48,7 @@ func resetDNS(iface *net.Interface) error {
 	args := []string{"-setdnsservers", iface.Name, "empty"}
 
 	if err := exec.Command(cmd, args...).Run(); err != nil {
-		mainLog.Error().Err(err).Msgf("resetDNS failed")
+		mainLog.Load().Error().Err(err).Msgf("resetDNS failed")
 		return err
 	}
 	return nil

cmd/cli/os_freebsd.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"net"
@@ -14,7 +14,7 @@ import (
 func allocateIP(ip string) error {
 	cmd := exec.Command("ifconfig", "lo0", ip, "alias")
 	if err := cmd.Run(); err != nil {
-		mainLog.Error().Err(err).Msg("allocateIP failed")
+		mainLog.Load().Error().Err(err).Msg("allocateIP failed")
 		return err
 	}
 	return nil
@@ -23,7 +23,7 @@ func allocateIP(ip string) error {
 func deAllocateIP(ip string) error {
 	cmd := exec.Command("ifconfig", "lo0", ip, "-alias")
 	if err := cmd.Run(); err != nil {
-		mainLog.Error().Err(err).Msg("deAllocateIP failed")
+		mainLog.Load().Error().Err(err).Msg("deAllocateIP failed")
 		return err
 	}
 	return nil
@@ -33,7 +33,7 @@ func deAllocateIP(ip string) error {
 func setDNS(iface *net.Interface, nameservers []string) error {
 	r, err := dns.NewOSConfigurator(logf, iface.Name)
 	if err != nil {
-		mainLog.Error().Err(err).Msg("failed to create DNS OS configurator")
+		mainLog.Load().Error().Err(err).Msg("failed to create DNS OS configurator")
 		return err
 	}
 
@@ -43,7 +43,7 @@ func setDNS(iface *net.Interface, nameservers []string) error {
 	}
 
 	if err := r.SetDNS(dns.OSConfig{Nameservers: ns}); err != nil {
-		mainLog.Error().Err(err).Msg("failed to set DNS")
+		mainLog.Load().Error().Err(err).Msg("failed to set DNS")
 		return err
 	}
 	return nil
@@ -52,12 +52,12 @@ func setDNS(iface *net.Interface, nameservers []string) error {
 func resetDNS(iface *net.Interface) error {
 	r, err := dns.NewOSConfigurator(logf, iface.Name)
 	if err != nil {
-		mainLog.Error().Err(err).Msg("failed to create DNS OS configurator")
+		mainLog.Load().Error().Err(err).Msg("failed to create DNS OS configurator")
 		return err
 	}
 
 	if err := r.Close(); err != nil {
-		mainLog.Error().Err(err).Msg("failed to rollback DNS setting")
+		mainLog.Load().Error().Err(err).Msg("failed to rollback DNS setting")
 		return err
 	}
 	return nil

cmd/cli/os_linux.go

@@ -1,10 +1,11 @@
-package main
+package cli
 
 import (
 	"bufio"
 	"bytes"
 	"context"
 	"fmt"
+	"io"
 	"net"
 	"net/netip"
 	"os/exec"
@@ -23,12 +24,14 @@ import (
 	"github.com/Control-D-Inc/ctrld/internal/resolvconffile"
 )
 
+const resolvConfBackupFailedMsg = "open /etc/resolv.pre-ctrld-backup.conf: read-only file system"
+
 // allocate loopback ip
 // sudo ip a add 127.0.0.2/24 dev lo
 func allocateIP(ip string) error {
 	cmd := exec.Command("ip", "a", "add", ip+"/24", "dev", "lo")
 	if out, err := cmd.CombinedOutput(); err != nil {
-		mainLog.Error().Err(err).Msgf("allocateIP failed: %s", string(out))
+		mainLog.Load().Error().Err(err).Msgf("allocateIP failed: %s", string(out))
 		return err
 	}
 	return nil
@@ -37,7 +40,7 @@ func allocateIP(ip string) error {
 func deAllocateIP(ip string) error {
 	cmd := exec.Command("ip", "a", "del", ip+"/24", "dev", "lo")
 	if err := cmd.Run(); err != nil {
-		mainLog.Error().Err(err).Msg("deAllocateIP failed")
+		mainLog.Load().Error().Err(err).Msg("deAllocateIP failed")
 		return err
 	}
 	return nil
@@ -49,7 +52,7 @@ const maxSetDNSAttempts = 5
 func setDNS(iface *net.Interface, nameservers []string) error {
 	r, err := dns.NewOSConfigurator(logf, iface.Name)
 	if err != nil {
-		mainLog.Error().Err(err).Msg("failed to create DNS OS configurator")
+		mainLog.Load().Error().Err(err).Msg("failed to create DNS OS configurator")
 		return err
 	}
 
@@ -63,8 +66,23 @@ func setDNS(iface *net.Interface, nameservers []string) error {
 		SearchDomains: []dnsname.FQDN{},
 	}
 
+	trySystemdResolve := false
 	for i := 0; i < maxSetDNSAttempts; i++ {
 		if err := r.SetDNS(osConfig); err != nil {
+			if strings.Contains(err.Error(), "Rejected send message") &&
+				strings.Contains(err.Error(), "org.freedesktop.network1.Manager") {
+				mainLog.Load().Warn().Msg("Interfaces are managed by systemd-networkd, switch to systemd-resolve for setting DNS")
+				trySystemdResolve = true
+				break
+			}
+			// This error happens on read-only file system, which causes ctrld failed to create backup
+			// for /etc/resolv.conf file. It is ok, because the DNS is still set anyway, and restore
+			// DNS will fallback to use DHCP if there's no backup /etc/resolv.conf file.
+			// The error format is controlled by us, so checking for error string is fine.
+			// See: ../../internal/dns/direct.go:L278
+			if r.Mode() == "direct" && strings.Contains(err.Error(), resolvConfBackupFailedMsg) {
+				return nil
+			}
 			return err
 		}
 		currentNS := currentDNS(iface)
@@ -72,7 +90,27 @@ func setDNS(iface *net.Interface, nameservers []string) error {
 			return nil
 		}
 	}
-	mainLog.Debug().Msg("DNS was not set for some reason")
+	if trySystemdResolve {
+		// Stop systemd-networkd and retry setting DNS.
+		if out, err := exec.Command("systemctl", "stop", "systemd-networkd").CombinedOutput(); err != nil {
+			return fmt.Errorf("%s: %w", string(out), err)
+		}
+		args := []string{"--interface=" + iface.Name, "--set-domain=~"}
+		for _, nameserver := range nameservers {
+			args = append(args, "--set-dns="+nameserver)
+		}
+		for i := 0; i < maxSetDNSAttempts; i++ {
+			if out, err := exec.Command("systemd-resolve", args...).CombinedOutput(); err != nil {
+				return fmt.Errorf("%s: %w", string(out), err)
+			}
+			currentNS := currentDNS(iface)
+			if reflect.DeepEqual(currentNS, nameservers) {
+				return nil
+			}
+			time.Sleep(time.Second)
+		}
+	}
+	mainLog.Load().Debug().Msg("DNS was not set for some reason")
 	return nil
 }
 
@@ -81,10 +119,14 @@ func resetDNS(iface *net.Interface) (err error) {
 		if err == nil {
 			return
 		}
+		// Start systemd-networkd if present.
+		if exe, _ := exec.LookPath("/lib/systemd/systemd-networkd"); exe != "" {
+			_ = exec.Command("systemctl", "start", "systemd-networkd").Run()
+		}
 		if r, oerr := dns.NewOSConfigurator(logf, iface.Name); oerr == nil {
 			_ = r.SetDNS(dns.OSConfig{})
 			if err := r.Close(); err != nil {
-				mainLog.Error().Err(err).Msg("failed to rollback DNS setting")
+				mainLog.Load().Error().Err(err).Msg("failed to rollback DNS setting")
 				return
 			}
 			err = nil
@@ -112,17 +154,17 @@ func resetDNS(iface *net.Interface) (err error) {
 	}
 
 	// TODO(cuonglm): handle DHCPv6 properly.
-	if ctrldnet.SupportsIPv6() {
+	if ctrldnet.IPv6Available(ctx) {
 		c := client6.NewClient()
 		conversation, err := c.Exchange(iface.Name)
-		if err != nil {
+		if err != nil && !errAddrInUse(err) {
-			mainLog.Debug().Err(err).Msg("could not exchange DHCPv6")
+			mainLog.Load().Debug().Err(err).Msg("could not exchange DHCPv6")
 		}
 		for _, packet := range conversation {
 			if packet.Type() == dhcpv6.MessageTypeReply {
 				msg, err := packet.GetInnerMessage()
 				if err != nil {
-					mainLog.Debug().Err(err).Msg("could not get inner DHCPv6 message")
+					mainLog.Load().Debug().Err(err).Msg("could not get inner DHCPv6 message")
 					return nil
 				}
 				nameservers := msg.Options.DNS()
@@ -139,7 +181,7 @@ func resetDNS(iface *net.Interface) (err error) {
 }
 
 func currentDNS(iface *net.Interface) []string {
-	for _, fn := range []getDNS{getDNSByResolvectl, getDNSByNmcli, resolvconffile.NameServers} {
+	for _, fn := range []getDNS{getDNSByResolvectl, getDNSBySystemdResolved, getDNSByNmcli, resolvconffile.NameServers} {
 		if ns := fn(iface.Name); len(ns) > 0 {
 			return ns
 		}
@@ -160,6 +202,36 @@ func getDNSByResolvectl(iface string) []string {
 	return nil
 }
 
+func getDNSBySystemdResolved(iface string) []string {
+	b, err := exec.Command("systemd-resolve", "--status", iface).Output()
+	if err != nil {
+		return nil
+	}
+	return getDNSBySystemdResolvedFromReader(bytes.NewReader(b))
+}
+
+func getDNSBySystemdResolvedFromReader(r io.Reader) []string {
+	scanner := bufio.NewScanner(r)
+	var ret []string
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if len(ret) > 0 {
+			if net.ParseIP(line) != nil {
+				ret = append(ret, line)
+			}
+			continue
+		}
+		after, found := strings.CutPrefix(line, "DNS Servers: ")
+		if !found {
+			continue
+		}
+		if net.ParseIP(after) != nil {
+			ret = append(ret, after)
+		}
+	}
+	return ret
+}
+
 func getDNSByNmcli(iface string) []string {
 	b, err := exec.Command("nmcli", "dev", "show", iface).Output()
 	if err != nil {

cmd/cli/os_linux_test.go

@@ -0,0 +1,23 @@
+package cli
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func Test_getDNSBySystemdResolvedFromReader(t *testing.T) {
+	r := strings.NewReader(`Link 2 (eth0)
+      Current Scopes: DNS
+       LLMNR setting: yes
+MulticastDNS setting: no
+      DNSSEC setting: no
+    DNSSEC supported: no
+         DNS Servers: 8.8.8.8
+                      8.8.4.4`)
+	want := []string{"8.8.8.8", "8.8.4.4"}
+	ns := getDNSBySystemdResolvedFromReader(r)
+	if !reflect.DeepEqual(ns, want) {
+		t.Logf("unexpected result, want: %v, got: %v", want, ns)
+	}
+}

cmd/cli/os_others.go

@@ -1,6 +1,6 @@
 //go:build !linux && !darwin && !freebsd
 
-package main
+package cli
 
 // TODO(cuonglm): implement.
 func allocateIP(ip string) error {

cmd/cli/os_windows.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"errors"
@@ -30,12 +30,12 @@ func setDNS(iface *net.Interface, nameservers []string) error {
 func resetDNS(iface *net.Interface) error {
 	if ctrldnet.SupportsIPv6ListenLocal() {
 		if output, err := netsh("interface", "ipv6", "set", "dnsserver", strconv.Itoa(iface.Index), "dhcp"); err != nil {
-			mainLog.Warn().Err(err).Msgf("failed to reset ipv6 DNS: %s", string(output))
+			mainLog.Load().Warn().Err(err).Msgf("failed to reset ipv6 DNS: %s", string(output))
 		}
 	}
 	output, err := netsh("interface", "ipv4", "set", "dnsserver", strconv.Itoa(iface.Index), "dhcp")
 	if err != nil {
-		mainLog.Error().Err(err).Msgf("failed to reset ipv4 DNS: %s", string(output))
+		mainLog.Load().Error().Err(err).Msgf("failed to reset ipv4 DNS: %s", string(output))
 		return err
 	}
 	return nil
@@ -49,7 +49,7 @@ func setPrimaryDNS(iface *net.Interface, dns string) error {
 	idx := strconv.Itoa(iface.Index)
 	output, err := netsh("interface", ipVer, "set", "dnsserver", idx, "static", dns)
 	if err != nil {
-		mainLog.Error().Err(err).Msgf("failed to set primary DNS: %s", string(output))
+		mainLog.Load().Error().Err(err).Msgf("failed to set primary DNS: %s", string(output))
 		return err
 	}
 	if ipVer == "ipv4" && ctrldnet.SupportsIPv6ListenLocal() {
@@ -67,7 +67,7 @@ func addSecondaryDNS(iface *net.Interface, dns string) error {
 	}
 	output, err := netsh("interface", ipVer, "add", "dns", strconv.Itoa(iface.Index), dns, "index=2")
 	if err != nil {
-		mainLog.Warn().Err(err).Msgf("failed to add secondary DNS: %s", string(output))
+		mainLog.Load().Warn().Err(err).Msgf("failed to add secondary DNS: %s", string(output))
 	}
 	return nil
 }
@@ -79,12 +79,12 @@ func netsh(args ...string) ([]byte, error) {
 func currentDNS(iface *net.Interface) []string {
 	luid, err := winipcfg.LUIDFromIndex(uint32(iface.Index))
 	if err != nil {
-		mainLog.Error().Err(err).Msg("failed to get interface LUID")
+		mainLog.Load().Error().Err(err).Msg("failed to get interface LUID")
 		return nil
 	}
 	nameservers, err := luid.DNS()
 	if err != nil {
-		mainLog.Error().Err(err).Msg("failed to get interface DNS")
+		mainLog.Load().Error().Err(err).Msg("failed to get interface DNS")
 		return nil
 	}
 	ns := make([]string, 0, len(nameservers))

cmd/cli/prog.go

@@ -0,0 +1,392 @@
+package cli
+
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+	"net"
+	"net/url"
+	"os"
+	"runtime"
+	"strconv"
+	"sync"
+	"syscall"
+
+	"github.com/kardianos/service"
+	"tailscale.com/net/interfaces"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/clientinfo"
+	"github.com/Control-D-Inc/ctrld/internal/dnscache"
+	"github.com/Control-D-Inc/ctrld/internal/router"
+)
+
+const (
+	defaultSemaphoreCap  = 256
+	ctrldLogUnixSock     = "ctrld_start.sock"
+	ctrldControlUnixSock = "ctrld_control.sock"
+)
+
+var logf = func(format string, args ...any) {
+	mainLog.Load().Debug().Msgf(format, args...)
+}
+
+var svcConfig = &service.Config{
+	Name:        "ctrld",
+	DisplayName: "Control-D Helper Service",
+	Option:      service.KeyValue{},
+}
+
+var useSystemdResolved = false
+
+type prog struct {
+	mu      sync.Mutex
+	waitCh  chan struct{}
+	stopCh  chan struct{}
+	logConn net.Conn
+	cs      *controlServer
+
+	cfg     *ctrld.Config
+	cache   dnscache.Cacher
+	sema    semaphore
+	ciTable *clientinfo.Table
+	router  router.Router
+
+	started       chan struct{}
+	onStartedDone chan struct{}
+	onStarted     []func()
+	onStopped     []func()
+}
+
+func (p *prog) Start(s service.Service) error {
+	p.cfg = &cfg
+	go p.run()
+	return nil
+}
+
+func (p *prog) preRun() {
+	if !service.Interactive() {
+		p.setDNS()
+	}
+	if runtime.GOOS == "darwin" {
+		p.onStopped = append(p.onStopped, func() {
+			if !service.Interactive() {
+				p.resetDNS()
+			}
+		})
+	}
+}
+
+func (p *prog) run() {
+	// Wait the caller to signal that we can do our logic.
+	<-p.waitCh
+	p.preRun()
+	numListeners := len(p.cfg.Listener)
+	p.started = make(chan struct{}, numListeners)
+	p.onStartedDone = make(chan struct{})
+	if p.cfg.Service.CacheEnable {
+		cacher, err := dnscache.NewLRUCache(p.cfg.Service.CacheSize)
+		if err != nil {
+			mainLog.Load().Error().Err(err).Msg("failed to create cacher, caching is disabled")
+		} else {
+			p.cache = cacher
+		}
+	}
+	p.sema = &chanSemaphore{ready: make(chan struct{}, defaultSemaphoreCap)}
+	if mcr := p.cfg.Service.MaxConcurrentRequests; mcr != nil {
+		n := *mcr
+		if n == 0 {
+			p.sema = &noopSemaphore{}
+		} else {
+			p.sema = &chanSemaphore{ready: make(chan struct{}, n)}
+		}
+	}
+	var wg sync.WaitGroup
+	wg.Add(len(p.cfg.Listener))
+
+	for _, nc := range p.cfg.Network {
+		for _, cidr := range nc.Cidrs {
+			_, ipNet, err := net.ParseCIDR(cidr)
+			if err != nil {
+				mainLog.Load().Error().Err(err).Str("network", nc.Name).Str("cidr", cidr).Msg("invalid cidr")
+				continue
+			}
+			nc.IPNets = append(nc.IPNets, ipNet)
+		}
+	}
+	for n := range p.cfg.Upstream {
+		uc := p.cfg.Upstream[n]
+		uc.Init()
+		if uc.BootstrapIP == "" {
+			uc.SetupBootstrapIP()
+			mainLog.Load().Info().Msgf("bootstrap IPs for upstream.%s: %q", n, uc.BootstrapIPs())
+		} else {
+			mainLog.Load().Info().Str("bootstrap_ip", uc.BootstrapIP).Msgf("using bootstrap IP for upstream.%s", n)
+		}
+		uc.SetCertPool(rootCertPool)
+		go uc.Ping()
+	}
+
+	p.ciTable = clientinfo.NewTable(&cfg, defaultRouteIP(), cdUID)
+	if leaseFile := p.cfg.Service.DHCPLeaseFile; leaseFile != "" {
+		mainLog.Load().Debug().Msgf("watching custom lease file: %s", leaseFile)
+		format := ctrld.LeaseFileFormat(p.cfg.Service.DHCPLeaseFileFormat)
+		p.ciTable.AddLeaseFile(leaseFile, format)
+	}
+
+	go func() {
+		p.ciTable.Init()
+		p.ciTable.RefreshLoop(p.stopCh)
+	}()
+	go p.watchLinkState()
+
+	for listenerNum := range p.cfg.Listener {
+		p.cfg.Listener[listenerNum].Init()
+		go func(listenerNum string) {
+			defer wg.Done()
+			listenerConfig := p.cfg.Listener[listenerNum]
+			upstreamConfig := p.cfg.Upstream[listenerNum]
+			if upstreamConfig == nil {
+				mainLog.Load().Warn().Msgf("no default upstream for: [listener.%s]", listenerNum)
+			}
+			addr := net.JoinHostPort(listenerConfig.IP, strconv.Itoa(listenerConfig.Port))
+			mainLog.Load().Info().Msgf("starting DNS server on listener.%s: %s", listenerNum, addr)
+			if err := p.serveDNS(listenerNum); err != nil {
+				mainLog.Load().Fatal().Err(err).Msgf("unable to start dns proxy on listener.%s", listenerNum)
+			}
+		}(listenerNum)
+	}
+
+	for i := 0; i < numListeners; i++ {
+		<-p.started
+	}
+	for _, f := range p.onStarted {
+		f()
+	}
+	close(p.onStartedDone)
+
+	// Stop writing log to unix socket.
+	consoleWriter.Out = os.Stdout
+	initLoggingWithBackup(false)
+	if p.logConn != nil {
+		_ = p.logConn.Close()
+	}
+	if p.cs != nil {
+		p.registerControlServerHandler()
+		if err := p.cs.start(); err != nil {
+			mainLog.Load().Warn().Err(err).Msg("could not start control server")
+		}
+	}
+	wg.Wait()
+}
+
+func (p *prog) Stop(s service.Service) error {
+	mainLog.Load().Info().Msg("Service stopped")
+	close(p.stopCh)
+	if err := p.deAllocateIP(); err != nil {
+		mainLog.Load().Error().Err(err).Msg("de-allocate ip failed")
+		return err
+	}
+	return nil
+}
+
+func (p *prog) allocateIP(ip string) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if !p.cfg.Service.AllocateIP {
+		return nil
+	}
+	return allocateIP(ip)
+}
+
+func (p *prog) deAllocateIP() error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if !p.cfg.Service.AllocateIP {
+		return nil
+	}
+	for _, lc := range p.cfg.Listener {
+		if err := deAllocateIP(lc.IP); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p *prog) setDNS() {
+	if cfg.Listener == nil {
+		return
+	}
+	if iface == "" {
+		return
+	}
+	if iface == "auto" {
+		iface = defaultIfaceName()
+	}
+	lc := cfg.FirstListener()
+	if lc == nil {
+		return
+	}
+	logger := mainLog.Load().With().Str("iface", iface).Logger()
+	netIface, err := netInterface(iface)
+	if err != nil {
+		logger.Error().Err(err).Msg("could not get interface")
+		return
+	}
+	if err := setupNetworkManager(); err != nil {
+		logger.Error().Err(err).Msg("could not patch NetworkManager")
+		return
+	}
+
+	logger.Debug().Msg("setting DNS for interface")
+	ns := lc.IP
+	switch {
+	case lc.IsDirectDnsListener():
+		// If ctrld is direct listener, use 127.0.0.1 as nameserver.
+		ns = "127.0.0.1"
+	case lc.Port != 53:
+		ns = "127.0.0.1"
+		if resolver := router.LocalResolverIP(); resolver != "" {
+			ns = resolver
+		}
+	default:
+		// If we ever reach here, it means ctrld is running on lc.IP port 53,
+		// so we could just use lc.IP as nameserver.
+	}
+
+	nameservers := []string{ns}
+	if needRFC1918Listeners(lc) {
+		nameservers = append(nameservers, rfc1918Addresses()...)
+	}
+	if err := setDNS(netIface, nameservers); err != nil {
+		logger.Error().Err(err).Msgf("could not set DNS for interface")
+		return
+	}
+	logger.Debug().Msg("setting DNS successfully")
+}
+
+func (p *prog) resetDNS() {
+	if iface == "" {
+		return
+	}
+	if iface == "auto" {
+		iface = defaultIfaceName()
+	}
+	logger := mainLog.Load().With().Str("iface", iface).Logger()
+	netIface, err := netInterface(iface)
+	if err != nil {
+		logger.Error().Err(err).Msg("could not get interface")
+		return
+	}
+	if err := restoreNetworkManager(); err != nil {
+		logger.Error().Err(err).Msg("could not restore NetworkManager")
+		return
+	}
+	logger.Debug().Msg("Restoring DNS for interface")
+	if err := resetDNS(netIface); err != nil {
+		logger.Error().Err(err).Msgf("could not reset DNS")
+		return
+	}
+	logger.Debug().Msg("Restoring DNS successfully")
+}
+
+func randomLocalIP() string {
+	n := rand.Intn(254-2) + 2
+	return fmt.Sprintf("127.0.0.%d", n)
+}
+
+func randomPort() int {
+	max := 1<<16 - 1
+	min := 1025
+	n := rand.Intn(max-min) + min
+	return n
+}
+
+// runLogServer starts a unix listener, use by startCmd to gather log from runCmd.
+func runLogServer(sockPath string) net.Conn {
+	addr, err := net.ResolveUnixAddr("unix", sockPath)
+	if err != nil {
+		mainLog.Load().Warn().Err(err).Msg("invalid log sock path")
+		return nil
+	}
+	ln, err := net.ListenUnix("unix", addr)
+	if err != nil {
+		mainLog.Load().Warn().Err(err).Msg("could not listen log socket")
+		return nil
+	}
+	defer ln.Close()
+
+	server, err := ln.Accept()
+	if err != nil {
+		mainLog.Load().Warn().Err(err).Msg("could not accept connection")
+		return nil
+	}
+	return server
+}
+
+func errAddrInUse(err error) bool {
+	var opErr *net.OpError
+	if errors.As(err, &opErr) {
+		return errors.Is(opErr.Err, syscall.EADDRINUSE) || errors.Is(opErr.Err, windowsEADDRINUSE)
+	}
+	return false
+}
+
+var _ = errAddrInUse
+
+// https://learn.microsoft.com/en-us/windows/win32/winsock/windows-sockets-error-codes-2
+var (
+	windowsECONNREFUSED = syscall.Errno(10061)
+	windowsENETUNREACH  = syscall.Errno(10051)
+	windowsEINVAL       = syscall.Errno(10022)
+	windowsEADDRINUSE   = syscall.Errno(10048)
+)
+
+func errUrlNetworkError(err error) bool {
+	var urlErr *url.Error
+	if errors.As(err, &urlErr) {
+		var opErr *net.OpError
+		if errors.As(urlErr.Err, &opErr) {
+			if opErr.Temporary() {
+				return true
+			}
+			switch {
+			case errors.Is(opErr.Err, syscall.ECONNREFUSED),
+				errors.Is(opErr.Err, syscall.EINVAL),
+				errors.Is(opErr.Err, syscall.ENETUNREACH),
+				errors.Is(opErr.Err, windowsENETUNREACH),
+				errors.Is(opErr.Err, windowsEINVAL),
+				errors.Is(opErr.Err, windowsECONNREFUSED):
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// defaultRouteIP returns IP string of the default route if present, prefer IPv4 over IPv6.
+func defaultRouteIP() string {
+	if dr, err := interfaces.DefaultRoute(); err == nil {
+		if netIface, err := netInterface(dr.InterfaceName); err == nil {
+			addrs, _ := netIface.Addrs()
+			do := func(v4 bool) net.IP {
+				for _, addr := range addrs {
+					if netIP, ok := addr.(*net.IPNet); ok && netIP.IP.IsPrivate() {
+						if v4 {
+							return netIP.IP.To4()
+						}
+						return netIP.IP
+					}
+				}
+				return nil
+			}
+			if ip := do(true); ip != nil {
+				return ip.String()
+			}
+			if ip := do(false); ip != nil {
+				return ip.String()
+			}
+		}
+	}
+	return ""
+}

cmd/cli/prog_darwin.go

@@ -0,0 +1,11 @@
+package cli
+
+import (
+	"github.com/kardianos/service"
+)
+
+func setDependencies(svc *service.Config) {}
+
+func setWorkingDirectory(svc *service.Config, dir string) {
+	svc.WorkingDirectory = dir
+}

cmd/cli/prog_freebsd.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import (
 	"os"
@@ -6,12 +6,6 @@ import (
 	"github.com/kardianos/service"
 )
 
-func (p *prog) preRun() {
-	if !service.Interactive() {
-		p.setDNS()
-	}
-}
-
 func setDependencies(svc *service.Config) {
 	// TODO(cuonglm): remove once https://github.com/kardianos/service/issues/359 fixed.
 	_ = os.MkdirAll("/usr/local/etc/rc.d", 0755)

cmd/cli/prog_linux.go

@@ -0,0 +1,32 @@
+package cli
+
+import (
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld/internal/dns"
+	"github.com/Control-D-Inc/ctrld/internal/router"
+)
+
+func init() {
+	if r, err := dns.NewOSConfigurator(func(format string, args ...any) {}, "lo"); err == nil {
+		useSystemdResolved = r.Mode() == "systemd-resolved"
+	}
+}
+
+func setDependencies(svc *service.Config) {
+	svc.Dependencies = []string{
+		"Wants=network-online.target",
+		"After=network-online.target",
+		"Wants=NetworkManager-wait-online.service",
+		"After=NetworkManager-wait-online.service",
+		"Wants=systemd-networkd-wait-online.service",
+		"After=systemd-networkd-wait-online.service",
+	}
+	if routerDeps := router.ServiceDependencies(); len(routerDeps) > 0 {
+		svc.Dependencies = append(svc.Dependencies, routerDeps...)
+	}
+}
+
+func setWorkingDirectory(svc *service.Config, dir string) {
+	svc.WorkingDirectory = dir
+}

cmd/cli/prog_others.go

@@ -1,11 +1,9 @@
-//go:build !linux && !freebsd
+//go:build !linux && !freebsd && !darwin
 
-package main
+package cli
 
 import "github.com/kardianos/service"
 
-func (p *prog) preRun() {}
-
 func setDependencies(svc *service.Config) {}
 
 func setWorkingDirectory(svc *service.Config, dir string) {

cmd/cli/sema.go

@@ -0,0 +1,24 @@
+package cli
+
+type semaphore interface {
+	acquire()
+	release()
+}
+
+type noopSemaphore struct{}
+
+func (n noopSemaphore) acquire() {}
+
+func (n noopSemaphore) release() {}
+
+type chanSemaphore struct {
+	ready chan struct{}
+}
+
+func (c *chanSemaphore) acquire() {
+	c.ready <- struct{}{}
+}
+
+func (c *chanSemaphore) release() {
+	<-c.ready
+}

cmd/cli/service.go

@@ -0,0 +1,167 @@
+package cli
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld/internal/router"
+)
+
+// newService wraps service.New call to return service.Service
+// wrapper which is suitable for the current platform.
+func newService(i service.Interface, c *service.Config) (service.Service, error) {
+	s, err := service.New(i, c)
+	if err != nil {
+		return nil, err
+	}
+	switch {
+	case router.IsOldOpenwrt():
+		return &procd{&sysV{s}}, nil
+	case router.IsGLiNet():
+		return &sysV{s}, nil
+	case s.Platform() == "unix-systemv":
+		return &sysV{s}, nil
+	case s.Platform() == "linux-systemd":
+		return &systemd{s}, nil
+	}
+	return s, nil
+}
+
+// sysV wraps a service.Service, and provide start/stop/status command
+// base on "/etc/init.d/<service_name>".
+//
+// Use this on system where "service" command is not available, like GL.iNET router.
+type sysV struct {
+	service.Service
+}
+
+func (s *sysV) installed() bool {
+	fi, err := os.Stat("/etc/init.d/ctrld")
+	if err != nil {
+		return false
+	}
+	mode := fi.Mode()
+	return mode.IsRegular() && (mode&0111) != 0
+}
+
+func (s *sysV) Start() error {
+	if !s.installed() {
+		return service.ErrNotInstalled
+	}
+	_, err := exec.Command("/etc/init.d/ctrld", "start").CombinedOutput()
+	return err
+}
+
+func (s *sysV) Stop() error {
+	if !s.installed() {
+		return service.ErrNotInstalled
+	}
+	_, err := exec.Command("/etc/init.d/ctrld", "stop").CombinedOutput()
+	return err
+}
+
+func (s *sysV) Restart() error {
+	if !s.installed() {
+		return service.ErrNotInstalled
+	}
+	// We don't care about error returned by s.Stop,
+	// because the service may already be stopped.
+	_ = s.Stop()
+	return s.Start()
+}
+
+func (s *sysV) Status() (service.Status, error) {
+	if !s.installed() {
+		return service.StatusUnknown, service.ErrNotInstalled
+	}
+	return unixSystemVServiceStatus()
+}
+
+// procd wraps a service.Service, and provide start/stop command
+// base on "/etc/init.d/<service_name>", status command base on parsing "ps" command output.
+//
+// Use this on system where "/etc/init.d/<service_name> status" command is not available,
+// like old GL.iNET Opal router.
+type procd struct {
+	*sysV
+}
+
+func (s *procd) Status() (service.Status, error) {
+	if !s.installed() {
+		return service.StatusUnknown, service.ErrNotInstalled
+	}
+	exe, err := os.Executable()
+	if err != nil {
+		return service.StatusUnknown, nil
+	}
+	// Looking for something like "/sbin/ctrld run ".
+	shellCmd := fmt.Sprintf("ps | grep -q %q", exe+" [r]un ")
+	if err := exec.Command("sh", "-c", shellCmd).Run(); err != nil {
+		return service.StatusStopped, nil
+	}
+	return service.StatusRunning, nil
+}
+
+// procd wraps a service.Service, and provide status command to
+// report the status correctly.
+type systemd struct {
+	service.Service
+}
+
+func (s *systemd) Status() (service.Status, error) {
+	out, _ := exec.Command("systemctl", "status", "ctrld").CombinedOutput()
+	if bytes.Contains(out, []byte("/FAILURE)")) {
+		return service.StatusStopped, nil
+	}
+	return s.Service.Status()
+}
+
+type task struct {
+	f            func() error
+	abortOnError bool
+}
+
+func doTasks(tasks []task) bool {
+	var prevErr error
+	for _, task := range tasks {
+		if err := task.f(); err != nil {
+			if task.abortOnError {
+				mainLog.Load().Error().Msg(errors.Join(prevErr, err).Error())
+				return false
+			}
+			prevErr = err
+		}
+	}
+	return true
+}
+
+func checkHasElevatedPrivilege() {
+	ok, err := hasElevatedPrivilege()
+	if err != nil {
+		mainLog.Load().Error().Msgf("could not detect user privilege: %v", err)
+		return
+	}
+	if !ok {
+		mainLog.Load().Error().Msg("Please relaunch process with admin/root privilege.")
+		os.Exit(1)
+	}
+}
+
+func unixSystemVServiceStatus() (service.Status, error) {
+	out, err := exec.Command("/etc/init.d/ctrld", "status").CombinedOutput()
+	if err != nil {
+		return service.StatusUnknown, nil
+	}
+
+	switch string(bytes.ToLower(bytes.TrimSpace(out))) {
+	case "running":
+		return service.StatusRunning, nil
+	default:
+		return service.StatusStopped, nil
+	}
+}

cmd/cli/service_others.go

@@ -1,6 +1,6 @@
 //go:build !windows
 
-package main
+package cli
 
 import (
 	"os"

cmd/cli/service_windows.go

@@ -1,4 +1,4 @@
-package main
+package cli
 
 import "golang.org/x/sys/windows"
 

cmd/ctrld/cli.go

@@ -1,738 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"context"
-	"encoding/base64"
-	"errors"
-	"fmt"
-	"log"
-	"net"
-	"net/netip"
-	"os"
-	"os/exec"
-	"path/filepath"
-	"runtime"
-	"strconv"
-	"strings"
-	"time"
-
-	"github.com/fsnotify/fsnotify"
-
-	"github.com/go-playground/validator/v10"
-	"github.com/kardianos/service"
-	"github.com/miekg/dns"
-	"github.com/pelletier/go-toml/v2"
-	"github.com/spf13/cobra"
-	"github.com/spf13/viper"
-	"tailscale.com/logtail/backoff"
-	"tailscale.com/net/interfaces"
-
-	"github.com/Control-D-Inc/ctrld"
-	"github.com/Control-D-Inc/ctrld/internal/controld"
-	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
-)
-
-const selfCheckFQDN = "verify.controld.com"
-
-var (
-	v                    = viper.NewWithOptions(viper.KeyDelimiter("::"))
-	defaultConfigWritten = false
-	defaultConfigFile    = "ctrld.toml"
-)
-
-var basicModeFlags = []string{"listen", "primary_upstream", "secondary_upstream", "domains"}
-
-func isNoConfigStart(cmd *cobra.Command) bool {
-	for _, flagName := range basicModeFlags {
-		if cmd.Flags().Lookup(flagName).Changed {
-			return true
-		}
-	}
-	return false
-}
-
-const rootShortDesc = `
-        __         .__       .___
-  _____/  |________|  |    __| _/
-_/ ___\   __\_  __ \  |   / __ |
-\  \___|  |  |  | \/  |__/ /_/ |
- \___  >__|  |__|  |____/\____ |
-     \/ dns forwarding proxy  \/
-`
-
-func initCLI() {
-	// Enable opening via explorer.exe on Windows.
-	// See: https://github.com/spf13/cobra/issues/844.
-	cobra.MousetrapHelpText = ""
-	cobra.EnableCommandSorting = false
-
-	rootCmd := &cobra.Command{
-		Use:     "ctrld",
-		Short:   strings.TrimLeft(rootShortDesc, "\n"),
-		Version: "1.1.2",
-	}
-	rootCmd.PersistentFlags().CountVarP(
-		&verbose,
-		"verbose",
-		"v",
-		`verbose log output, "-v" basic logging, "-vv" debug level logging`,
-	)
-	rootCmd.SetHelpCommand(&cobra.Command{Hidden: true})
-	rootCmd.CompletionOptions.HiddenDefaultCmd = true
-
-	runCmd := &cobra.Command{
-		Use:   "run",
-		Short: "Run the DNS proxy server",
-		Args:  cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			if daemon && runtime.GOOS == "windows" {
-				log.Fatal("Cannot run in daemon mode. Please install a Windows service.")
-			}
-			noConfigStart := isNoConfigStart(cmd)
-			writeDefaultConfig := !noConfigStart && configBase64 == ""
-			configs := []struct {
-				name    string
-				written bool
-			}{
-				// For compatibility, we check for config.toml first, but only read it if exists.
-				{"config", false},
-				{"ctrld", writeDefaultConfig},
-			}
-			for _, config := range configs {
-				ctrld.SetConfigName(v, config.name)
-				v.SetConfigFile(configPath)
-				if readConfigFile(config.written) {
-					break
-				}
-			}
-
-			readBase64Config()
-			processNoConfigFlags(noConfigStart)
-			if err := v.Unmarshal(&cfg); err != nil {
-				log.Fatalf("failed to unmarshal config: %v", err)
-			}
-			fmt.Println("starting ctrld...")
-			// Wait for network up.
-			if !ctrldnet.Up() {
-				log.Fatal("network is not up yet")
-			}
-			processLogAndCacheFlags()
-			// Log config do not have thing to validate, so it's safe to init log here,
-			// so it's able to log information in processCDFlags.
-			initLogging()
-			processCDFlags()
-			if err := ctrld.ValidateConfig(validator.New(), &cfg); err != nil {
-				log.Fatalf("invalid config: %v", err)
-			}
-			initCache()
-
-			if daemon {
-				exe, err := os.Executable()
-				if err != nil {
-					mainLog.Error().Err(err).Msg("failed to find the binary")
-					os.Exit(1)
-				}
-				curDir, err := os.Getwd()
-				if err != nil {
-					mainLog.Error().Err(err).Msg("failed to get current working directory")
-					os.Exit(1)
-				}
-				// If running as daemon, re-run the command in background, with daemon off.
-				cmd := exec.Command(exe, append(os.Args[1:], "-d=false")...)
-				cmd.Dir = curDir
-				if err := cmd.Start(); err != nil {
-					mainLog.Error().Err(err).Msg("failed to start process as daemon")
-					os.Exit(1)
-				}
-				mainLog.Info().Int("pid", cmd.Process.Pid).Msg("DNS proxy started")
-				os.Exit(0)
-			}
-
-			s, err := service.New(&prog{}, svcConfig)
-			if err != nil {
-				mainLog.Fatal().Err(err).Msg("failed create new service")
-			}
-			serviceLogger, err := s.Logger(nil)
-			if err != nil {
-				mainLog.Error().Err(err).Msg("failed to get service logger")
-				return
-			}
-
-			if err := s.Run(); err != nil {
-				if sErr := serviceLogger.Error(err); sErr != nil {
-					mainLog.Error().Err(sErr).Msg("failed to write service log")
-				}
-				mainLog.Error().Err(err).Msg("failed to start service")
-			}
-		},
-	}
-	runCmd.Flags().BoolVarP(&daemon, "daemon", "d", false, "Run as daemon")
-	runCmd.Flags().StringVarP(&configPath, "config", "c", "", "Path to config file")
-	runCmd.Flags().StringVarP(&configBase64, "base64_config", "", "", "Base64 encoded config")
-	runCmd.Flags().StringVarP(&listenAddress, "listen", "", "", "Listener address and port, in format: address:port")
-	runCmd.Flags().StringVarP(&primaryUpstream, "primary_upstream", "", "", "Primary upstream endpoint")
-	runCmd.Flags().StringVarP(&secondaryUpstream, "secondary_upstream", "", "", "Secondary upstream endpoint")
-	runCmd.Flags().StringSliceVarP(&domains, "domains", "", nil, "List of domain to apply in a split DNS policy")
-	runCmd.Flags().StringVarP(&logPath, "log", "", "", "Path to log file")
-	runCmd.Flags().IntVarP(&cacheSize, "cache_size", "", 0, "Enable cache with size items")
-	runCmd.Flags().StringVarP(&cdUID, "cd", "", "", "Control D resolver uid")
-	runCmd.Flags().StringVarP(&homedir, "homedir", "", "", "")
-	_ = runCmd.Flags().MarkHidden("homedir")
-	runCmd.Flags().StringVarP(&iface, "iface", "", "", `Update DNS setting for iface, "auto" means the default interface gateway`)
-	_ = runCmd.Flags().MarkHidden("iface")
-
-	rootCmd.AddCommand(runCmd)
-
-	startCmd := &cobra.Command{
-		PreRun: checkHasElevatedPrivilege,
-		Use:    "start",
-		Short:  "Install and start the ctrld service",
-		Args:   cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			sc := &service.Config{}
-			*sc = *svcConfig
-			osArgs := os.Args[2:]
-			if os.Args[1] == "service" {
-				osArgs = os.Args[3:]
-			}
-			setDependencies(sc)
-			sc.Arguments = append([]string{"run"}, osArgs...)
-
-			// No config path, generating config in HOME directory.
-			noConfigStart := isNoConfigStart(cmd)
-			writeDefaultConfig := !noConfigStart && configBase64 == ""
-			if configPath != "" {
-				v.SetConfigFile(configPath)
-			}
-			if dir, err := os.UserHomeDir(); err == nil {
-				setWorkingDirectory(sc, dir)
-				if configPath == "" && writeDefaultConfig {
-					defaultConfigFile = filepath.Join(dir, defaultConfigFile)
-					v.SetConfigFile(defaultConfigFile)
-				}
-				sc.Arguments = append(sc.Arguments, "--homedir="+dir)
-			}
-
-			readConfigFile(writeDefaultConfig && cdUID == "")
-			if err := v.Unmarshal(&cfg); err != nil {
-				log.Fatalf("failed to unmarshal config: %v", err)
-			}
-
-			logPath := cfg.Service.LogPath
-			cfg.Service.LogPath = ""
-			initLogging()
-			cfg.Service.LogPath = logPath
-
-			processCDFlags()
-			// On Windows, the service will be run as SYSTEM, so if ctrld start as Admin,
-			// the user home dir is different, so pass specific arguments that relevant here.
-			if runtime.GOOS == "windows" {
-				if configPath == "" {
-					sc.Arguments = append(sc.Arguments, "--config="+defaultConfigFile)
-				}
-			}
-
-			prog := &prog{}
-			s, err := service.New(prog, sc)
-			if err != nil {
-				stderrMsg(err.Error())
-				return
-			}
-			tasks := []task{
-				{s.Stop, false},
-				{s.Uninstall, false},
-				{s.Install, false},
-				{s.Start, true},
-			}
-			if doTasks(tasks) {
-				status, err := s.Status()
-				if err != nil {
-					mainLog.Warn().Err(err).Msg("could not get service status")
-					return
-				}
-
-				status = selfCheckStatus(status)
-				switch status {
-				case service.StatusRunning:
-					mainLog.Info().Msg("Service started")
-				default:
-					mainLog.Error().Msg("Service did not start, please check system/service log for details error")
-					if runtime.GOOS == "linux" {
-						prog.resetDNS()
-					}
-					os.Exit(1)
-				}
-				prog.setDNS()
-			}
-		},
-	}
-	// Keep these flags in sync with runCmd above, except for "-d".
-	startCmd.Flags().StringVarP(&configPath, "config", "c", "", "Path to config file")
-	startCmd.Flags().StringVarP(&configBase64, "base64_config", "", "", "Base64 encoded config")
-	startCmd.Flags().StringVarP(&listenAddress, "listen", "", "", "Listener address and port, in format: address:port")
-	startCmd.Flags().StringVarP(&primaryUpstream, "primary_upstream", "", "", "Primary upstream endpoint")
-	startCmd.Flags().StringVarP(&secondaryUpstream, "secondary_upstream", "", "", "Secondary upstream endpoint")
-	startCmd.Flags().StringSliceVarP(&domains, "domains", "", nil, "List of domain to apply in a split DNS policy")
-	startCmd.Flags().StringVarP(&logPath, "log", "", "", "Path to log file")
-	startCmd.Flags().IntVarP(&cacheSize, "cache_size", "", 0, "Enable cache with size items")
-	startCmd.Flags().StringVarP(&cdUID, "cd", "", "", "Control D resolver uid")
-	startCmd.Flags().StringVarP(&iface, "iface", "", "", `Update DNS setting for iface, "auto" means the default interface gateway`)
-
-	stopCmd := &cobra.Command{
-		PreRun: checkHasElevatedPrivilege,
-		Use:    "stop",
-		Short:  "Stop the ctrld service",
-		Args:   cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			prog := &prog{}
-			s, err := service.New(prog, svcConfig)
-			if err != nil {
-				stderrMsg(err.Error())
-				return
-			}
-			initLogging()
-			if doTasks([]task{{s.Stop, true}}) {
-				prog.resetDNS()
-				mainLog.Info().Msg("Service stopped")
-			}
-		},
-	}
-	stopCmd.Flags().StringVarP(&iface, "iface", "", "", `Reset DNS setting for iface, "auto" means the default interface gateway`)
-
-	restartCmd := &cobra.Command{
-		PreRun: checkHasElevatedPrivilege,
-		Use:    "restart",
-		Short:  "Restart the ctrld service",
-		Args:   cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			s, err := service.New(&prog{}, svcConfig)
-			if err != nil {
-				stderrMsg(err.Error())
-				return
-			}
-			initLogging()
-			if doTasks([]task{{s.Restart, true}}) {
-				stdoutMsg("Service restarted")
-			}
-		},
-	}
-
-	statusCmd := &cobra.Command{
-		Use:   "status",
-		Short: "Show status of the ctrld service",
-		Args:  cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			s, err := service.New(&prog{}, svcConfig)
-			if err != nil {
-				stderrMsg(err.Error())
-				return
-			}
-			status, err := s.Status()
-			if err != nil {
-				stderrMsg(err.Error())
-				os.Exit(1)
-			}
-			switch status {
-			case service.StatusUnknown:
-				stdoutMsg("Unknown status")
-				os.Exit(2)
-			case service.StatusRunning:
-				stdoutMsg("Service is running")
-				os.Exit(0)
-			case service.StatusStopped:
-				stdoutMsg("Service is stopped")
-				os.Exit(1)
-			}
-		},
-	}
-
-	uninstallCmd := &cobra.Command{
-		PreRun: checkHasElevatedPrivilege,
-		Use:    "uninstall",
-		Short:  "Stop and uninstall the ctrld service",
-		Args:   cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			prog := &prog{}
-			s, err := service.New(prog, svcConfig)
-			if err != nil {
-				stderrMsg(err.Error())
-				return
-			}
-			tasks := []task{
-				{s.Stop, false},
-				{s.Uninstall, true},
-			}
-			initLogging()
-			if doTasks(tasks) {
-				prog.resetDNS()
-				mainLog.Info().Msg("Service uninstalled")
-				return
-			}
-		},
-	}
-	uninstallCmd.Flags().StringVarP(&iface, "iface", "", "auto", `Reset DNS setting for iface, "auto" means the default interface gateway`)
-
-	listIfacesCmd := &cobra.Command{
-		Use:   "list",
-		Short: "List network interfaces of the host",
-		Args:  cobra.NoArgs,
-		Run: func(cmd *cobra.Command, args []string) {
-			err := interfaces.ForeachInterface(func(i interfaces.Interface, prefixes []netip.Prefix) {
-				fmt.Printf("Index : %d\n", i.Index)
-				fmt.Printf("Name  : %s\n", i.Name)
-				addrs, _ := i.Addrs()
-				for i, ipaddr := range addrs {
-					if i == 0 {
-						fmt.Printf("Addrs : %v\n", ipaddr)
-						continue
-					}
-					fmt.Printf("        %v\n", ipaddr)
-				}
-				for i, dns := range currentDNS(i.Interface) {
-					if i == 0 {
-						fmt.Printf("DNS   : %s\n", dns)
-						continue
-					}
-					fmt.Printf("      : %s\n", dns)
-				}
-				println()
-			})
-			if err != nil {
-				stderrMsg(err.Error())
-			}
-		},
-	}
-	interfacesCmd := &cobra.Command{
-		Use:   "interfaces",
-		Short: "Manage network interfaces",
-		Args:  cobra.OnlyValidArgs,
-		ValidArgs: []string{
-			listIfacesCmd.Use,
-		},
-	}
-	interfacesCmd.AddCommand(listIfacesCmd)
-
-	serviceCmd := &cobra.Command{
-		Use:   "service",
-		Short: "Manage ctrld service",
-		Args:  cobra.OnlyValidArgs,
-		ValidArgs: []string{
-			statusCmd.Use,
-			stopCmd.Use,
-			restartCmd.Use,
-			statusCmd.Use,
-			uninstallCmd.Use,
-			interfacesCmd.Use,
-		},
-	}
-	serviceCmd.AddCommand(startCmd)
-	serviceCmd.AddCommand(stopCmd)
-	serviceCmd.AddCommand(restartCmd)
-	serviceCmd.AddCommand(statusCmd)
-	serviceCmd.AddCommand(uninstallCmd)
-	serviceCmd.AddCommand(interfacesCmd)
-	rootCmd.AddCommand(serviceCmd)
-	startCmdAlias := &cobra.Command{
-		PreRun: checkHasElevatedPrivilege,
-		Use:    "start",
-		Short:  "Quick start service and configure DNS on interface",
-		Run: func(cmd *cobra.Command, args []string) {
-			if !cmd.Flags().Changed("iface") {
-				os.Args = append(os.Args, "--iface="+ifaceStartStop)
-			}
-			iface = ifaceStartStop
-			startCmd.Run(cmd, args)
-		},
-	}
-	startCmdAlias.Flags().StringVarP(&ifaceStartStop, "iface", "", "auto", `Update DNS setting for iface, "auto" means the default interface gateway`)
-	startCmdAlias.Flags().AddFlagSet(startCmd.Flags())
-	rootCmd.AddCommand(startCmdAlias)
-	stopCmdAlias := &cobra.Command{
-		PreRun: checkHasElevatedPrivilege,
-		Use:    "stop",
-		Short:  "Quick stop service and remove DNS from interface",
-		Run: func(cmd *cobra.Command, args []string) {
-			if !cmd.Flags().Changed("iface") {
-				os.Args = append(os.Args, "--iface="+ifaceStartStop)
-			}
-			iface = ifaceStartStop
-			stopCmd.Run(cmd, args)
-		},
-	}
-	stopCmdAlias.Flags().StringVarP(&ifaceStartStop, "iface", "", "auto", `Reset DNS setting for iface, "auto" means the default interface gateway`)
-	stopCmdAlias.Flags().AddFlagSet(stopCmd.Flags())
-	rootCmd.AddCommand(stopCmdAlias)
-
-	if err := rootCmd.Execute(); err != nil {
-		stderrMsg(err.Error())
-		os.Exit(1)
-	}
-}
-
-func writeConfigFile() error {
-	if cfu := v.ConfigFileUsed(); cfu != "" {
-		defaultConfigFile = cfu
-	} else if configPath != "" {
-		defaultConfigFile = configPath
-	}
-	f, err := os.OpenFile(defaultConfigFile, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, os.FileMode(0o644))
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-	if cdUID != "" {
-		if _, err := f.WriteString("# AUTO-GENERATED VIA CD FLAG - DO NOT MODIFY\n\n"); err != nil {
-			return err
-		}
-	}
-	enc := toml.NewEncoder(f).SetIndentTables(true)
-	if err := enc.Encode(&cfg); err != nil {
-		return err
-	}
-	if err := f.Close(); err != nil {
-		return err
-	}
-	return nil
-}
-
-func readConfigFile(writeDefaultConfig bool) bool {
-	// If err == nil, there's a config supplied via `--config`, no default config written.
-	err := v.ReadInConfig()
-	if err == nil {
-		fmt.Println("loading config file from:", v.ConfigFileUsed())
-		defaultConfigFile = v.ConfigFileUsed()
-		v.OnConfigChange(func(in fsnotify.Event) {
-			if err := v.UnmarshalKey("listener", &cfg.Listener); err != nil {
-				log.Printf("failed to unmarshal listener config: %v", err)
-				return
-			}
-		})
-		v.WatchConfig()
-		return true
-	}
-
-	if !writeDefaultConfig {
-		return false
-	}
-
-	// If error is viper.ConfigFileNotFoundError, write default config.
-	if _, ok := err.(viper.ConfigFileNotFoundError); ok {
-		if err := writeConfigFile(); err != nil {
-			log.Fatalf("failed to write default config file: %v", err)
-		} else {
-			fmt.Println("writing default config file to: " + defaultConfigFile)
-		}
-		defaultConfigWritten = true
-		return false
-	}
-	// Otherwise, report fatal error and exit.
-	log.Fatalf("failed to decode config file: %v", err)
-	return false
-}
-
-func readBase64Config() {
-	if configBase64 == "" {
-		return
-	}
-	configStr, err := base64.StdEncoding.DecodeString(configBase64)
-	if err != nil {
-		log.Fatalf("invalid base64 config: %v", err)
-	}
-	if err := v.ReadConfig(bytes.NewReader(configStr)); err != nil {
-		log.Fatalf("failed to read base64 config: %v", err)
-	}
-}
-
-func processNoConfigFlags(noConfigStart bool) {
-	if !noConfigStart {
-		return
-	}
-	if listenAddress == "" || primaryUpstream == "" {
-		log.Fatal(`"listen" and "primary_upstream" flags must be set in no config mode`)
-	}
-	processListenFlag()
-
-	upstream := map[string]*ctrld.UpstreamConfig{
-		"0": {
-			Name:     primaryUpstream,
-			Endpoint: primaryUpstream,
-			Type:     ctrld.ResolverTypeDOH,
-		},
-	}
-	if secondaryUpstream != "" {
-		upstream["1"] = &ctrld.UpstreamConfig{
-			Name:     secondaryUpstream,
-			Endpoint: secondaryUpstream,
-			Type:     ctrld.ResolverTypeLegacy,
-		}
-		rules := make([]ctrld.Rule, 0, len(domains))
-		for _, domain := range domains {
-			rules = append(rules, ctrld.Rule{domain: []string{"upstream.1"}})
-		}
-		lc := v.Get("listener").(map[string]*ctrld.ListenerConfig)["0"]
-		lc.Policy = &ctrld.ListenerPolicyConfig{Name: "My Policy", Rules: rules}
-	}
-	v.Set("upstream", upstream)
-}
-
-func processCDFlags() {
-	if cdUID == "" {
-		return
-	}
-	if iface == "" {
-		iface = "auto"
-	}
-	logger := mainLog.With().Str("mode", "cd").Logger()
-	logger.Info().Msgf("fetching Controld D configuration from API: %s", cdUID)
-	resolverConfig, err := controld.FetchResolverConfig(cdUID)
-	if uer, ok := err.(*controld.UtilityErrorResponse); ok && uer.ErrorField.Code == controld.InvalidConfigCode {
-		s, err := service.New(&prog{}, svcConfig)
-		if err != nil {
-			logger.Warn().Err(err).Msg("failed to create new service")
-			return
-		}
-
-		if netIface, _ := netInterface(iface); netIface != nil {
-			if err := restoreNetworkManager(); err != nil {
-				logger.Error().Err(err).Msg("could not restore NetworkManager")
-				return
-			}
-			logger.Debug().Str("iface", netIface.Name).Msg("Restoring DNS for interface")
-			if err := resetDNS(netIface); err != nil {
-				logger.Warn().Err(err).Msg("something went wrong while restoring DNS")
-			} else {
-				logger.Debug().Str("iface", netIface.Name).Msg("Restoring DNS successfully")
-			}
-		}
-
-		tasks := []task{{s.Uninstall, true}}
-		if doTasks(tasks) {
-			logger.Info().Msg("uninstalled service")
-		}
-		logger.Fatal().Err(uer).Msg("failed to fetch resolver config")
-	}
-	if err != nil {
-		logger.Warn().Err(err).Msg("could not fetch resolver config")
-		return
-	}
-
-	logger.Info().Msg("generating ctrld config from Controld-D configuration")
-	cfg = ctrld.Config{}
-	cfg.Network = make(map[string]*ctrld.NetworkConfig)
-	cfg.Network["0"] = &ctrld.NetworkConfig{
-		Name:  "Network 0",
-		Cidrs: []string{"0.0.0.0/0"},
-	}
-	cfg.Upstream = make(map[string]*ctrld.UpstreamConfig)
-	cfg.Upstream["0"] = &ctrld.UpstreamConfig{
-		Endpoint: resolverConfig.DOH,
-		Type:     ctrld.ResolverTypeDOH,
-		Timeout:  5000,
-	}
-	rules := make([]ctrld.Rule, 0, len(resolverConfig.Exclude))
-	for _, domain := range resolverConfig.Exclude {
-		rules = append(rules, ctrld.Rule{domain: []string{}})
-	}
-	cfg.Listener = make(map[string]*ctrld.ListenerConfig)
-	cfg.Listener["0"] = &ctrld.ListenerConfig{
-		IP:   "127.0.0.1",
-		Port: 53,
-		Policy: &ctrld.ListenerPolicyConfig{
-			Name:  "My Policy",
-			Rules: rules,
-		},
-	}
-
-	processLogAndCacheFlags()
-	if err := writeConfigFile(); err != nil {
-		logger.Fatal().Err(err).Msg("failed to write config file")
-	} else {
-		logger.Info().Msg("writing config file to: " + defaultConfigFile)
-	}
-}
-
-func processListenFlag() {
-	if listenAddress == "" {
-		return
-	}
-	host, portStr, err := net.SplitHostPort(listenAddress)
-	if err != nil {
-		log.Fatalf("invalid listener address: %v", err)
-	}
-	port, err := strconv.Atoi(portStr)
-	if err != nil {
-		log.Fatalf("invalid port number: %v", err)
-	}
-	lc := &ctrld.ListenerConfig{
-		IP:   host,
-		Port: port,
-	}
-	v.Set("listener", map[string]*ctrld.ListenerConfig{
-		"0": lc,
-	})
-}
-
-func processLogAndCacheFlags() {
-	if logPath != "" {
-		cfg.Service.LogLevel = "debug"
-		cfg.Service.LogPath = logPath
-	}
-
-	if cacheSize != 0 {
-		cfg.Service.CacheEnable = true
-		cfg.Service.CacheSize = cacheSize
-	}
-	v.Set("service", cfg.Service)
-}
-
-func netInterface(ifaceName string) (*net.Interface, error) {
-	if ifaceName == "auto" {
-		ifaceName = defaultIfaceName()
-	}
-	var iface *net.Interface
-	err := interfaces.ForeachInterface(func(i interfaces.Interface, prefixes []netip.Prefix) {
-		if i.Name == ifaceName {
-			iface = i.Interface
-		}
-	})
-	if iface == nil {
-		return nil, errors.New("interface not found")
-	}
-	if err := patchNetIfaceName(iface); err != nil {
-		return nil, err
-	}
-	return iface, err
-}
-
-func defaultIfaceName() string {
-	dri, err := interfaces.DefaultRouteInterface()
-	if err != nil {
-		mainLog.Fatal().Err(err).Msg("failed to get default route interface")
-	}
-	return dri
-}
-
-func selfCheckStatus(status service.Status) service.Status {
-	c := new(dns.Client)
-	bo := backoff.NewBackoff("self-check", logf, 10*time.Second)
-	bo.LogLongerThan = 500 * time.Millisecond
-	ctx := context.Background()
-	err := errors.New("query failed")
-	maxAttempts := 20
-	mainLog.Debug().Msg("Performing self-check")
-	for i := 0; i < maxAttempts; i++ {
-		lc := cfg.Listener["0"]
-		m := new(dns.Msg)
-		m.SetQuestion(selfCheckFQDN+".", dns.TypeA)
-		m.RecursionDesired = true
-		r, _, _ := c.ExchangeContext(ctx, m, net.JoinHostPort(lc.IP, strconv.Itoa(lc.Port)))
-		if r != nil && r.Rcode == dns.RcodeSuccess && len(r.Answer) > 0 {
-			mainLog.Debug().Msgf("self-check against %q succeeded", selfCheckFQDN)
-			return status
-		}
-		bo.BackOff(ctx, err)
-	}
-	mainLog.Debug().Msgf("self-check against %q failed", selfCheckFQDN)
-	return service.StatusUnknown
-}

cmd/ctrld/dns_proxy.go

@@ -1,348 +0,0 @@
-package main
-
-import (
-	"context"
-	"crypto/rand"
-	"encoding/hex"
-	"fmt"
-	"net"
-	"runtime"
-	"strconv"
-	"strings"
-	"time"
-
-	"github.com/miekg/dns"
-	"golang.org/x/sync/errgroup"
-
-	"github.com/Control-D-Inc/ctrld"
-	"github.com/Control-D-Inc/ctrld/internal/dnscache"
-	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
-)
-
-const staleTTL = 60 * time.Second
-
-func (p *prog) serveDNS(listenerNum string) error {
-	listenerConfig := p.cfg.Listener[listenerNum]
-	// make sure ip is allocated
-	if allocErr := p.allocateIP(listenerConfig.IP); allocErr != nil {
-		mainLog.Error().Err(allocErr).Str("ip", listenerConfig.IP).Msg("serveUDP: failed to allocate listen ip")
-		return allocErr
-	}
-	var failoverRcodes []int
-	if listenerConfig.Policy != nil {
-		failoverRcodes = listenerConfig.Policy.FailoverRcodeNumbers
-	}
-	handler := dns.HandlerFunc(func(w dns.ResponseWriter, m *dns.Msg) {
-		q := m.Question[0]
-		domain := canonicalName(q.Name)
-		reqId := requestID()
-		fmtSrcToDest := fmtRemoteToLocal(listenerNum, w.RemoteAddr().String(), w.LocalAddr().String())
-		t := time.Now()
-		ctx := context.WithValue(context.Background(), ctrld.ReqIdCtxKey{}, reqId)
-		ctrld.Log(ctx, mainLog.Debug(), "%s received query: %s %s", fmtSrcToDest, dns.TypeToString[q.Qtype], domain)
-		upstreams, matched := p.upstreamFor(ctx, listenerNum, listenerConfig, w.RemoteAddr(), domain)
-		var answer *dns.Msg
-		if !matched && listenerConfig.Restricted {
-			answer = new(dns.Msg)
-			answer.SetRcode(m, dns.RcodeRefused)
-
-		} else {
-			answer = p.proxy(ctx, upstreams, failoverRcodes, m)
-			rtt := time.Since(t)
-			ctrld.Log(ctx, mainLog.Debug(), "received response of %d bytes in %s", answer.Len(), rtt)
-		}
-		if err := w.WriteMsg(answer); err != nil {
-			ctrld.Log(ctx, mainLog.Error().Err(err), "serveUDP: failed to send DNS response to client")
-		}
-	})
-
-	g := new(errgroup.Group)
-	for _, proto := range []string{"udp", "tcp"} {
-		proto := proto
-		// On Windows, there's no easy way for disabling/removing IPv6 DNS resolver, so we check whether we can
-		// listen on ::1, then spawn a listener for receiving DNS requests.
-		if runtime.GOOS == "windows" && ctrldnet.SupportsIPv6ListenLocal() {
-			g.Go(func() error {
-				s := &dns.Server{
-					Addr:    net.JoinHostPort("::1", strconv.Itoa(listenerConfig.Port)),
-					Net:     proto,
-					Handler: handler,
-				}
-				if err := s.ListenAndServe(); err != nil {
-					mainLog.Error().Err(err).Msg("could not serving on ::1")
-				}
-				return nil
-			})
-		}
-		g.Go(func() error {
-			s := &dns.Server{
-				Addr:    net.JoinHostPort(listenerConfig.IP, strconv.Itoa(listenerConfig.Port)),
-				Net:     proto,
-				Handler: handler,
-			}
-			if err := s.ListenAndServe(); err != nil {
-				mainLog.Error().Err(err).Msgf("could not listen and serve on: %s", s.Addr)
-				return err
-			}
-			return nil
-		})
-	}
-	return g.Wait()
-}
-
-func (p *prog) upstreamFor(ctx context.Context, defaultUpstreamNum string, lc *ctrld.ListenerConfig, addr net.Addr, domain string) ([]string, bool) {
-	upstreams := []string{"upstream." + defaultUpstreamNum}
-	matchedPolicy := "no policy"
-	matchedNetwork := "no network"
-	matchedRule := "no rule"
-	matched := false
-
-	defer func() {
-		if !matched && lc.Restricted {
-			ctrld.Log(ctx, mainLog.Info(), "query refused, %s does not match any network policy", addr.String())
-			return
-		}
-		ctrld.Log(ctx, mainLog.Info(), "%s, %s, %s -> %v", matchedPolicy, matchedNetwork, matchedRule, upstreams)
-	}()
-
-	if lc.Policy == nil {
-		return upstreams, false
-	}
-
-	do := func(policyUpstreams []string) {
-		upstreams = append([]string(nil), policyUpstreams...)
-	}
-
-	for _, rule := range lc.Policy.Rules {
-		// There's only one entry per rule, config validation ensures this.
-		for source, targets := range rule {
-			if source == domain || wildcardMatches(source, domain) {
-				matchedPolicy = lc.Policy.Name
-				matchedRule = source
-				do(targets)
-				matched = true
-				return upstreams, matched
-			}
-		}
-	}
-
-	var sourceIP net.IP
-	switch addr := addr.(type) {
-	case *net.UDPAddr:
-		sourceIP = addr.IP
-	case *net.TCPAddr:
-		sourceIP = addr.IP
-	}
-	for _, rule := range lc.Policy.Networks {
-		for source, targets := range rule {
-			networkNum := strings.TrimPrefix(source, "network.")
-			nc := p.cfg.Network[networkNum]
-			if nc == nil {
-				continue
-			}
-
-			for _, ipNet := range nc.IPNets {
-				if ipNet.Contains(sourceIP) {
-					matchedPolicy = lc.Policy.Name
-					matchedNetwork = source
-					do(targets)
-					matched = true
-					return upstreams, matched
-				}
-			}
-		}
-	}
-
-	return upstreams, matched
-}
-
-func (p *prog) proxy(ctx context.Context, upstreams []string, failoverRcodes []int, msg *dns.Msg) *dns.Msg {
-	var staleAnswer *dns.Msg
-	serveStaleCache := p.cache != nil && p.cfg.Service.CacheServeStale
-	upstreamConfigs := p.upstreamConfigsFromUpstreamNumbers(upstreams)
-	if len(upstreamConfigs) == 0 {
-		upstreamConfigs = []*ctrld.UpstreamConfig{osUpstreamConfig}
-		upstreams = []string{"upstream.os"}
-	}
-	// Inverse query should not be cached: https://www.rfc-editor.org/rfc/rfc1035#section-7.4
-	if p.cache != nil && msg.Question[0].Qtype != dns.TypePTR {
-		for _, upstream := range upstreams {
-			cachedValue := p.cache.Get(dnscache.NewKey(msg, upstream))
-			if cachedValue == nil {
-				continue
-			}
-			answer := cachedValue.Msg.Copy()
-			answer.SetRcode(msg, answer.Rcode)
-			now := time.Now()
-			if cachedValue.Expire.After(now) {
-				ctrld.Log(ctx, mainLog.Debug(), "hit cached response")
-				setCachedAnswerTTL(answer, now, cachedValue.Expire)
-				return answer
-			}
-			staleAnswer = answer
-		}
-	}
-	resolve1 := func(n int, upstreamConfig *ctrld.UpstreamConfig, msg *dns.Msg) (*dns.Msg, error) {
-		ctrld.Log(ctx, mainLog.Debug(), "sending query to %s: %s", upstreams[n], upstreamConfig.Name)
-		dnsResolver, err := ctrld.NewResolver(upstreamConfig)
-		if err != nil {
-			ctrld.Log(ctx, mainLog.Error().Err(err), "failed to create resolver")
-			return nil, err
-		}
-		resolveCtx, cancel := context.WithCancel(ctx)
-		defer cancel()
-		if upstreamConfig.Timeout > 0 {
-			timeoutCtx, cancel := context.WithTimeout(resolveCtx, time.Millisecond*time.Duration(upstreamConfig.Timeout))
-			defer cancel()
-			resolveCtx = timeoutCtx
-		}
-		return dnsResolver.Resolve(resolveCtx, msg)
-	}
-	resolve := func(n int, upstreamConfig *ctrld.UpstreamConfig, msg *dns.Msg) *dns.Msg {
-		answer, err := resolve1(n, upstreamConfig, msg)
-		if err != nil {
-			ctrld.Log(ctx, mainLog.Debug().Err(err), "could not resolve query on first attempt, retrying...")
-			// If any error occurred, re-bootstrap transport/ip, retry the request.
-			upstreamConfig.ReBootstrap()
-			answer, err = resolve1(n, upstreamConfig, msg)
-			if err == nil {
-				return answer
-			}
-			ctrld.Log(ctx, mainLog.Error().Err(err), "failed to resolve query")
-			return nil
-		}
-		return answer
-	}
-	for n, upstreamConfig := range upstreamConfigs {
-		answer := resolve(n, upstreamConfig, msg)
-		if answer == nil {
-			if serveStaleCache && staleAnswer != nil {
-				ctrld.Log(ctx, mainLog.Debug(), "serving stale cached response")
-				now := time.Now()
-				setCachedAnswerTTL(staleAnswer, now, now.Add(staleTTL))
-				return staleAnswer
-			}
-			continue
-		}
-		if answer.Rcode != dns.RcodeSuccess && len(upstreamConfigs) > 1 && containRcode(failoverRcodes, answer.Rcode) {
-			ctrld.Log(ctx, mainLog.Debug(), "failover rcode matched, process to next upstream")
-			continue
-		}
-		if p.cache != nil {
-			ttl := ttlFromMsg(answer)
-			now := time.Now()
-			expired := now.Add(time.Duration(ttl) * time.Second)
-			if cachedTTL := p.cfg.Service.CacheTTLOverride; cachedTTL > 0 {
-				expired = now.Add(time.Duration(cachedTTL) * time.Second)
-			}
-			setCachedAnswerTTL(answer, now, expired)
-			p.cache.Add(dnscache.NewKey(msg, upstreams[n]), dnscache.NewValue(answer, expired))
-			ctrld.Log(ctx, mainLog.Debug(), "add cached response")
-		}
-		return answer
-	}
-	ctrld.Log(ctx, mainLog.Error(), "all upstreams failed")
-	answer := new(dns.Msg)
-	answer.SetRcode(msg, dns.RcodeServerFailure)
-	return answer
-}
-
-func (p *prog) upstreamConfigsFromUpstreamNumbers(upstreams []string) []*ctrld.UpstreamConfig {
-	upstreamConfigs := make([]*ctrld.UpstreamConfig, 0, len(upstreams))
-	for _, upstream := range upstreams {
-		upstreamNum := strings.TrimPrefix(upstream, "upstream.")
-		upstreamConfigs = append(upstreamConfigs, p.cfg.Upstream[upstreamNum])
-	}
-	return upstreamConfigs
-}
-
-// canonicalName returns canonical name from FQDN with "." trimmed.
-func canonicalName(fqdn string) string {
-	q := strings.TrimSpace(fqdn)
-	q = strings.TrimSuffix(q, ".")
-	// https://datatracker.ietf.org/doc/html/rfc4343
-	q = strings.ToLower(q)
-
-	return q
-}
-
-func wildcardMatches(wildcard, domain string) bool {
-	// Wildcard match.
-	wildCardParts := strings.Split(wildcard, "*")
-	if len(wildCardParts) != 2 {
-		return false
-	}
-
-	switch {
-	case len(wildCardParts[0]) > 0 && len(wildCardParts[1]) > 0:
-		// Domain must match both prefix and suffix.
-		return strings.HasPrefix(domain, wildCardParts[0]) && strings.HasSuffix(domain, wildCardParts[1])
-
-	case len(wildCardParts[1]) > 0:
-		// Only suffix must match.
-		return strings.HasSuffix(domain, wildCardParts[1])
-
-	case len(wildCardParts[0]) > 0:
-		// Only prefix must match.
-		return strings.HasPrefix(domain, wildCardParts[0])
-	}
-
-	return false
-}
-
-func fmtRemoteToLocal(listenerNum, remote, local string) string {
-	return fmt.Sprintf("%s -> listener.%s: %s:", remote, listenerNum, local)
-}
-
-func requestID() string {
-	b := make([]byte, 3) // 6 chars
-	if _, err := rand.Read(b); err != nil {
-		panic(err)
-	}
-	return hex.EncodeToString(b)
-}
-
-func containRcode(rcodes []int, rcode int) bool {
-	for i := range rcodes {
-		if rcodes[i] == rcode {
-			return true
-		}
-	}
-	return false
-}
-
-func setCachedAnswerTTL(answer *dns.Msg, now, expiredTime time.Time) {
-	ttlSecs := expiredTime.Sub(now).Seconds()
-	if ttlSecs < 0 {
-		return
-	}
-
-	ttl := uint32(ttlSecs)
-	for _, rr := range answer.Answer {
-		rr.Header().Ttl = ttl
-	}
-	for _, rr := range answer.Ns {
-		rr.Header().Ttl = ttl
-	}
-	for _, rr := range answer.Extra {
-		if rr.Header().Rrtype != dns.TypeOPT {
-			rr.Header().Ttl = ttl
-		}
-	}
-}
-
-func ttlFromMsg(msg *dns.Msg) uint32 {
-	for _, rr := range msg.Answer {
-		return rr.Header().Ttl
-	}
-	for _, rr := range msg.Ns {
-		return rr.Header().Ttl
-	}
-	return 0
-}
-
-var osUpstreamConfig = &ctrld.UpstreamConfig{
-	Name:    "OS resolver",
-	Type:    ctrld.ResolverTypeOS,
-	Timeout: 2000,
-}

cmd/ctrld/main.go

@@ -1,109 +1,7 @@
 package main
 
-import (
+import "github.com/Control-D-Inc/ctrld/cmd/cli"
-	"io"
-	"log"
-	"os"
-	"path/filepath"
-	"time"
-
-	"github.com/kardianos/service"
-	"github.com/rs/zerolog"
-
-	"github.com/Control-D-Inc/ctrld"
-)
-
-var (
-	configPath        string
-	configBase64      string
-	daemon            bool
-	listenAddress     string
-	primaryUpstream   string
-	secondaryUpstream string
-	domains           []string
-	logPath           string
-	homedir           string
-	cacheSize         int
-	cfg               ctrld.Config
-	verbose           int
-
-	rootLogger = zerolog.New(io.Discard)
-	mainLog    = rootLogger
-
-	cdUID          string
-	iface          string
-	ifaceStartStop string
-)
 
 func main() {
-	ctrld.InitConfig(v, "ctrld")
+	cli.Main()
-	initCLI()
-}
-
-func normalizeLogFilePath(logFilePath string) string {
-	if logFilePath == "" || filepath.IsAbs(logFilePath) || service.Interactive() {
-		return logFilePath
-	}
-	if homedir != "" {
-		return filepath.Join(homedir, logFilePath)
-	}
-	dir, _ := os.UserHomeDir()
-	if dir == "" {
-		return logFilePath
-	}
-	return filepath.Join(dir, logFilePath)
-}
-
-func initLogging() {
-	writers := []io.Writer{io.Discard}
-	if logFilePath := normalizeLogFilePath(cfg.Service.LogPath); logFilePath != "" {
-		// Create parent directory if necessary.
-		if err := os.MkdirAll(filepath.Dir(logFilePath), 0750); err != nil {
-			log.Printf("failed to create log path: %v", err)
-			os.Exit(1)
-		}
-		// Backup old log file with .1 suffix.
-		if err := os.Rename(logFilePath, logFilePath+".1"); err != nil && !os.IsNotExist(err) {
-			log.Printf("could not backup old log file: %v", err)
-		}
-		logFile, err := os.OpenFile(logFilePath, os.O_CREATE|os.O_RDWR, os.FileMode(0o600))
-		if err != nil {
-			log.Printf("failed to create log file: %v", err)
-			os.Exit(1)
-		}
-		writers = append(writers, logFile)
-	}
-	zerolog.TimeFieldFormat = zerolog.TimeFormatUnixMs
-	consoleWriter := zerolog.NewConsoleWriter(func(w *zerolog.ConsoleWriter) {
-		w.TimeFormat = time.StampMilli
-	})
-	writers = append(writers, consoleWriter)
-	multi := zerolog.MultiLevelWriter(writers...)
-	mainLog = mainLog.Output(multi).With().Timestamp().Logger()
-	// TODO: find a better way.
-	ctrld.ProxyLog = mainLog
-
-	zerolog.SetGlobalLevel(zerolog.InfoLevel)
-	logLevel := cfg.Service.LogLevel
-	if verbose > 1 {
-		logLevel = "debug"
-	}
-	if logLevel == "" {
-		return
-	}
-	level, err := zerolog.ParseLevel(logLevel)
-	if err != nil {
-		mainLog.Warn().Err(err).Msg("could not set log level")
-		return
-	}
-	zerolog.SetGlobalLevel(level)
-}
-
-func initCache() {
-	if !cfg.Service.CacheEnable {
-		return
-	}
-	if cfg.Service.CacheSize == 0 {
-		cfg.Service.CacheSize = 4096
-	}
 }

cmd/ctrld/prog.go

@@ -1,209 +0,0 @@
-package main
-
-import (
-	"errors"
-	"fmt"
-	"math/rand"
-	"net"
-	"os"
-	"strconv"
-	"sync"
-	"syscall"
-
-	"github.com/kardianos/service"
-
-	"github.com/Control-D-Inc/ctrld"
-	"github.com/Control-D-Inc/ctrld/internal/dnscache"
-)
-
-var logf = func(format string, args ...any) {
-	mainLog.Debug().Msgf(format, args...)
-}
-
-var errWindowsAddrInUse = syscall.Errno(0x2740)
-
-var svcConfig = &service.Config{
-	Name:        "ctrld",
-	DisplayName: "Control-D Helper Service",
-}
-
-type prog struct {
-	cfg   *ctrld.Config
-	cache dnscache.Cacher
-}
-
-func (p *prog) Start(s service.Service) error {
-	p.cfg = &cfg
-	go p.run()
-	return nil
-}
-
-func (p *prog) run() {
-	p.preRun()
-	if p.cfg.Service.CacheEnable {
-		cacher, err := dnscache.NewLRUCache(p.cfg.Service.CacheSize)
-		if err != nil {
-			mainLog.Error().Err(err).Msg("failed to create cacher, caching is disabled")
-		} else {
-			p.cache = cacher
-		}
-	}
-	var wg sync.WaitGroup
-	wg.Add(len(p.cfg.Listener))
-
-	for _, nc := range p.cfg.Network {
-		for _, cidr := range nc.Cidrs {
-			_, ipNet, err := net.ParseCIDR(cidr)
-			if err != nil {
-				mainLog.Error().Err(err).Str("network", nc.Name).Str("cidr", cidr).Msg("invalid cidr")
-				continue
-			}
-			nc.IPNets = append(nc.IPNets, ipNet)
-		}
-	}
-	for n := range p.cfg.Upstream {
-		uc := p.cfg.Upstream[n]
-		uc.Init()
-		if uc.BootstrapIP == "" {
-			uc.SetupBootstrapIP()
-			mainLog.Info().Str("bootstrap_ip", uc.BootstrapIP).Msgf("Setting bootstrap IP for upstream.%s", n)
-		} else {
-			mainLog.Info().Str("bootstrap_ip", uc.BootstrapIP).Msgf("Using bootstrap IP for upstream.%s", n)
-		}
-		uc.SetupTransport()
-	}
-
-	for listenerNum := range p.cfg.Listener {
-		p.cfg.Listener[listenerNum].Init()
-		go func(listenerNum string) {
-			defer wg.Done()
-			listenerConfig := p.cfg.Listener[listenerNum]
-			upstreamConfig := p.cfg.Upstream[listenerNum]
-			if upstreamConfig == nil {
-				mainLog.Error().Msgf("missing upstream config for: [listener.%s]", listenerNum)
-				return
-			}
-			addr := net.JoinHostPort(listenerConfig.IP, strconv.Itoa(listenerConfig.Port))
-			mainLog.Info().Msgf("Starting DNS server on listener.%s: %s", listenerNum, addr)
-			err := p.serveDNS(listenerNum)
-			if err != nil && !defaultConfigWritten && cdUID == "" {
-				mainLog.Fatal().Err(err).Msgf("Unable to start dns proxy on listener.%s", listenerNum)
-				return
-			}
-			if err == nil {
-				return
-			}
-
-			if opErr, ok := err.(*net.OpError); ok && listenerNum == "0" {
-				if sErr, ok := opErr.Err.(*os.SyscallError); ok && errors.Is(opErr.Err, syscall.EADDRINUSE) || errors.Is(sErr.Err, errWindowsAddrInUse) {
-					mainLog.Warn().Msgf("Address %s already in used, pick a random one", addr)
-					ip := randomLocalIP()
-					listenerConfig.IP = ip
-					port := listenerConfig.Port
-					cfg.Upstream = map[string]*ctrld.UpstreamConfig{"0": cfg.Upstream["0"]}
-					if err := writeConfigFile(); err != nil {
-						mainLog.Fatal().Err(err).Msg("failed to write config file")
-					} else {
-						mainLog.Info().Msg("writing config file to: " + defaultConfigFile)
-					}
-					p.cfg.Service.AllocateIP = true
-					p.preRun()
-					mainLog.Info().Msgf("Starting DNS server on listener.%s: %s", listenerNum, net.JoinHostPort(ip, strconv.Itoa(port)))
-					if err := p.serveDNS(listenerNum); err != nil {
-						mainLog.Fatal().Err(err).Msgf("Unable to start dns proxy on listener.%s", listenerNum)
-						return
-					}
-				}
-			}
-			mainLog.Fatal().Err(err).Msgf("Unable to start dns proxy on listener.%s", listenerNum)
-		}(listenerNum)
-	}
-
-	wg.Wait()
-}
-
-func (p *prog) Stop(s service.Service) error {
-	if err := p.deAllocateIP(); err != nil {
-		mainLog.Error().Err(err).Msg("de-allocate ip failed")
-		return err
-	}
-	mainLog.Info().Msg("Service stopped")
-	return nil
-}
-
-func (p *prog) allocateIP(ip string) error {
-	if !p.cfg.Service.AllocateIP {
-		return nil
-	}
-	return allocateIP(ip)
-}
-
-func (p *prog) deAllocateIP() error {
-	if !p.cfg.Service.AllocateIP {
-		return nil
-	}
-	for _, lc := range p.cfg.Listener {
-		if err := deAllocateIP(lc.IP); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func (p *prog) setDNS() {
-	if cfg.Listener == nil || cfg.Listener["0"] == nil {
-		return
-	}
-	if iface == "" {
-		return
-	}
-	if iface == "auto" {
-		iface = defaultIfaceName()
-	}
-	logger := mainLog.With().Str("iface", iface).Logger()
-	netIface, err := netInterface(iface)
-	if err != nil {
-		logger.Error().Err(err).Msg("could not get interface")
-		return
-	}
-	if err := setupNetworkManager(); err != nil {
-		logger.Error().Err(err).Msg("could not patch NetworkManager")
-		return
-	}
-	logger.Debug().Msg("setting DNS for interface")
-	if err := setDNS(netIface, []string{cfg.Listener["0"].IP}); err != nil {
-		logger.Error().Err(err).Msgf("could not set DNS for interface")
-		return
-	}
-	logger.Debug().Msg("setting DNS successfully")
-}
-
-func (p *prog) resetDNS() {
-	if iface == "" {
-		return
-	}
-	if iface == "auto" {
-		iface = defaultIfaceName()
-	}
-	logger := mainLog.With().Str("iface", iface).Logger()
-	netIface, err := netInterface(iface)
-	if err != nil {
-		logger.Error().Err(err).Msg("could not get interface")
-		return
-	}
-	if err := restoreNetworkManager(); err != nil {
-		logger.Error().Err(err).Msg("could not restore NetworkManager")
-		return
-	}
-	logger.Debug().Msg("Restoring DNS for interface")
-	if err := resetDNS(netIface); err != nil {
-		logger.Error().Err(err).Msgf("could not reset DNS")
-		return
-	}
-	logger.Debug().Msg("Restoring DNS successfully")
-}
-
-func randomLocalIP() string {
-	n := rand.Intn(254-2) + 2
-	return fmt.Sprintf("127.0.0.%d", n)
-}

cmd/ctrld/prog_linux.go

@@ -1,24 +0,0 @@
-package main
-
-import (
-	"github.com/kardianos/service"
-)
-
-func (p *prog) preRun() {
-	if !service.Interactive() {
-		p.setDNS()
-	}
-}
-
-func setDependencies(svc *service.Config) {
-	svc.Dependencies = []string{
-		"Wants=network-online.target",
-		"After=network-online.target",
-		"Wants=NetworkManager-wait-online.service",
-		"After=NetworkManager-wait-online.service",
-	}
-}
-
-func setWorkingDirectory(svc *service.Config, dir string) {
-	svc.WorkingDirectory = dir
-}

cmd/ctrld/service.go

@@ -1,45 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"os"
-
-	"github.com/spf13/cobra"
-)
-
-func stderrMsg(msg string) {
-	_, _ = fmt.Fprintln(os.Stderr, msg)
-}
-
-func stdoutMsg(msg string) {
-	_, _ = fmt.Fprintln(os.Stdout, msg)
-}
-
-type task struct {
-	f            func() error
-	abortOnError bool
-}
-
-func doTasks(tasks []task) bool {
-	for _, task := range tasks {
-		if err := task.f(); err != nil {
-			if task.abortOnError {
-				stderrMsg(err.Error())
-				return false
-			}
-		}
-	}
-	return true
-}
-
-func checkHasElevatedPrivilege(cmd *cobra.Command, args []string) {
-	ok, err := hasElevatedPrivilege()
-	if err != nil {
-		fmt.Printf("could not detect user privilege: %v", err)
-		return
-	}
-	if !ok {
-		fmt.Println("Please relaunch process with admin/root privilege.")
-		os.Exit(1)
-	}
-}

config.go

@@ -2,11 +2,20 @@ package ctrld
 
 import (
 	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"io"
+	"math/rand"
 	"net"
 	"net/http"
 	"net/url"
 	"os"
+	"runtime"
+	"sort"
+	"strconv"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -14,29 +23,59 @@ import (
 	"github.com/miekg/dns"
 	"github.com/spf13/viper"
 	"golang.org/x/sync/singleflight"
+	"tailscale.com/logtail/backoff"
 
 	"github.com/Control-D-Inc/ctrld/internal/dnsrcode"
 	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
 )
 
-// SetConfigName set the config name that ctrld will look for.
+// IpStackBoth ...
-func SetConfigName(v *viper.Viper, name string) {
+const (
-	v.SetConfigName(name)
+	// IpStackBoth indicates that ctrld will use either ipv4 or ipv6 for connecting to upstream,
+	// depending on which stack is available when receiving the DNS query.
+	IpStackBoth = "both"
+	// IpStackV4 indicates that ctrld will use only ipv4 for connecting to upstream.
+	IpStackV4 = "v4"
+	// IpStackV6 indicates that ctrld will use only ipv6 for connecting to upstream.
+	IpStackV6 = "v6"
+	// IpStackSplit indicates that ctrld will use either ipv4 or ipv6 for connecting to upstream,
+	// depending on the record type of the DNS query.
+	IpStackSplit = "split"
 
+	controlDComDomain = "controld.com"
+	controlDNetDomain = "controld.net"
+	controlDDevDomain = "controld.dev"
+)
+
+var (
+	controldParentDomains  = []string{controlDComDomain, controlDNetDomain, controlDDevDomain}
+	controldVerifiedDomain = map[string]string{
+		controlDComDomain: "verify.controld.com",
+		controlDDevDomain: "verify.controld.dev",
+	}
+)
+
+// SetConfigName set the config name that ctrld will look for.
+// DEPRECATED: use SetConfigNameWithPath instead.
+func SetConfigName(v *viper.Viper, name string) {
 	configPath := "$HOME"
 	// viper has its own way to get user home directory:  https://github.com/spf13/viper/blob/v1.14.0/util.go#L134
 	// To be consistent, we prefer os.UserHomeDir instead.
 	if homeDir, err := os.UserHomeDir(); err == nil {
 		configPath = homeDir
 	}
+	SetConfigNameWithPath(v, name, configPath)
+}
+
+// SetConfigNameWithPath set the config path and name that ctrld will look for.
+func SetConfigNameWithPath(v *viper.Viper, name, configPath string) {
+	v.SetConfigName(name)
 	v.AddConfigPath(configPath)
 	v.AddConfigPath(".")
 }
 
 // InitConfig initializes default config values for given *viper.Viper instance.
 func InitConfig(v *viper.Viper, name string) {
-	SetConfigName(v, name)
-
 	v.SetDefault("listener", map[string]*ListenerConfig{
 		"0": {
 			IP:   "127.0.0.1",
@@ -75,16 +114,72 @@ type Config struct {
 	Upstream map[string]*UpstreamConfig `mapstructure:"upstream" toml:"upstream" validate:"min=1,dive"`
 }
 
+// HasUpstreamSendClientInfo reports whether the config has any upstream
+// is configured to send client info to Control D DNS server.
+func (c *Config) HasUpstreamSendClientInfo() bool {
+	for _, uc := range c.Upstream {
+		if uc.UpstreamSendClientInfo() {
+			return true
+		}
+	}
+	return false
+}
+
+// FirstListener returns the first listener config of current config. Listeners are sorted numerically.
+//
+// It panics if Config has no listeners configured.
+func (c *Config) FirstListener() *ListenerConfig {
+	listeners := make([]int, 0, len(c.Listener))
+	for k := range c.Listener {
+		n, err := strconv.Atoi(k)
+		if err != nil {
+			continue
+		}
+		listeners = append(listeners, n)
+	}
+	if len(listeners) == 0 {
+		panic("missing listener config")
+	}
+	sort.Ints(listeners)
+	return c.Listener[strconv.Itoa(listeners[0])]
+}
+
+// FirstUpstream returns the first upstream of current config. Upstreams are sorted numerically.
+//
+// It panics if Config has no upstreams configured.
+func (c *Config) FirstUpstream() *UpstreamConfig {
+	upstreams := make([]int, 0, len(c.Upstream))
+	for k := range c.Upstream {
+		n, err := strconv.Atoi(k)
+		if err != nil {
+			continue
+		}
+		upstreams = append(upstreams, n)
+	}
+	if len(upstreams) == 0 {
+		panic("missing listener config")
+	}
+	sort.Ints(upstreams)
+	return c.Upstream[strconv.Itoa(upstreams[0])]
+}
+
 // ServiceConfig specifies the general ctrld config.
 type ServiceConfig struct {
-	LogLevel         string `mapstructure:"log_level" toml:"log_level,omitempty"`
+	LogLevel              string `mapstructure:"log_level" toml:"log_level,omitempty"`
-	LogPath          string `mapstructure:"log_path" toml:"log_path,omitempty"`
+	LogPath               string `mapstructure:"log_path" toml:"log_path,omitempty"`
-	CacheEnable      bool   `mapstructure:"cache_enable" toml:"cache_enable,omitempty"`
+	CacheEnable           bool   `mapstructure:"cache_enable" toml:"cache_enable,omitempty"`
-	CacheSize        int    `mapstructure:"cache_size" toml:"cache_size,omitempty"`
+	CacheSize             int    `mapstructure:"cache_size" toml:"cache_size,omitempty"`
-	CacheTTLOverride int    `mapstructure:"cache_ttl_override" toml:"cache_ttl_override,omitempty"`
+	CacheTTLOverride      int    `mapstructure:"cache_ttl_override" toml:"cache_ttl_override,omitempty"`
-	CacheServeStale  bool   `mapstructure:"cache_serve_stale" toml:"cache_serve_stale,omitempty"`
+	CacheServeStale       bool   `mapstructure:"cache_serve_stale" toml:"cache_serve_stale,omitempty"`
-	Daemon           bool   `mapstructure:"-" toml:"-"`
+	MaxConcurrentRequests *int   `mapstructure:"max_concurrent_requests" toml:"max_concurrent_requests,omitempty" validate:"omitempty,gte=0"`
-	AllocateIP       bool   `mapstructure:"-" toml:"-"`
+	DHCPLeaseFile         string `mapstructure:"dhcp_lease_file_path" toml:"dhcp_lease_file_path" validate:"omitempty,file"`
+	DHCPLeaseFileFormat   string `mapstructure:"dhcp_lease_file_format" toml:"dhcp_lease_file_format" validate:"required_unless=DHCPLeaseFile '',omitempty,oneof=dnsmasq isc-dhcp"`
+	DiscoverMDNS          *bool  `mapstructure:"discover_mdns" toml:"discover_mdns,omitempty"`
+	DiscoverARP           *bool  `mapstructure:"discover_arp" toml:"discover_dhcp,omitempty"`
+	DiscoverDHCP          *bool  `mapstructure:"discover_dhcp" toml:"discover_dhcp,omitempty"`
+	DiscoverPtr           *bool  `mapstructure:"discover_ptr" toml:"discover_ptr,omitempty"`
+	Daemon                bool   `mapstructure:"-" toml:"-"`
+	AllocateIP            bool   `mapstructure:"-" toml:"-"`
 }
 
 // NetworkConfig specifies configuration for networks where ctrld will handle requests.
@@ -96,28 +191,59 @@ type NetworkConfig struct {
 
 // UpstreamConfig specifies configuration for upstreams that ctrld will forward requests to.
 type UpstreamConfig struct {
-	Name              string            `mapstructure:"name" toml:"name,omitempty"`
+	Name        string `mapstructure:"name" toml:"name,omitempty"`
-	Type              string            `mapstructure:"type" toml:"type,omitempty" validate:"oneof=doh doh3 dot doq os legacy"`
+	Type        string `mapstructure:"type" toml:"type,omitempty" validate:"oneof=doh doh3 dot doq os legacy"`
-	Endpoint          string            `mapstructure:"endpoint" toml:"endpoint,omitempty" validate:"required_unless=Type os"`
+	Endpoint    string `mapstructure:"endpoint" toml:"endpoint,omitempty"`
-	BootstrapIP       string            `mapstructure:"bootstrap_ip" toml:"bootstrap_ip,omitempty"`
+	BootstrapIP string `mapstructure:"bootstrap_ip" toml:"bootstrap_ip,omitempty"`
-	Domain            string            `mapstructure:"-" toml:"-"`
+	Domain      string `mapstructure:"-" toml:"-"`
-	Timeout           int               `mapstructure:"timeout" toml:"timeout,omitempty" validate:"gte=0"`
+	IPStack     string `mapstructure:"ip_stack" toml:"ip_stack,omitempty" validate:"ipstack"`
-	transport         *http.Transport   `mapstructure:"-" toml:"-"`
+	Timeout     int    `mapstructure:"timeout" toml:"timeout,omitempty" validate:"gte=0"`
-	http3RoundTripper http.RoundTripper `mapstructure:"-" toml:"-"`
+	// The caller should not access this field directly.
+	// Use UpstreamSendClientInfo instead.
+	SendClientInfo *bool `mapstructure:"send_client_info" toml:"send_client_info,omitempty"`
 
-	g               singleflight.Group
+	g                  singleflight.Group
-	bootstrapIPs    []string
+	rebootstrap        atomic.Bool
-	nextBootstrapIP atomic.Uint32
+	bootstrapIPs       []string
+	bootstrapIPs4      []string
+	bootstrapIPs6      []string
+	transport          *http.Transport
+	transportOnce      sync.Once
+	transport4         *http.Transport
+	transport6         *http.Transport
+	http3RoundTripper  http.RoundTripper
+	http3RoundTripper4 http.RoundTripper
+	http3RoundTripper6 http.RoundTripper
+	certPool           *x509.CertPool
+	u                  *url.URL
 }
 
 // ListenerConfig specifies the networks configuration that ctrld will run on.
 type ListenerConfig struct {
-	IP         string                `mapstructure:"ip" toml:"ip,omitempty" validate:"ip"`
+	IP         string                `mapstructure:"ip" toml:"ip,omitempty" validate:"iporempty"`
-	Port       int                   `mapstructure:"port" toml:"port,omitempty" validate:"gt=0"`
+	Port       int                   `mapstructure:"port" toml:"port,omitempty" validate:"gte=0"`
 	Restricted bool                  `mapstructure:"restricted" toml:"restricted,omitempty"`
 	Policy     *ListenerPolicyConfig `mapstructure:"policy" toml:"policy,omitempty"`
 }
 
+// IsDirectDnsListener reports whether ctrld can be a direct listener on port 53.
+// It returns true only if ctrld can listen on port 53 for all interfaces. That means
+// there's no other software listening on port 53.
+//
+// If someone listening on port 53, or ctrld could only listen on port 53 for a specific
+// interface, ctrld could only be configured as a DNS forwarder.
+func (lc *ListenerConfig) IsDirectDnsListener() bool {
+	if lc == nil || lc.Port != 53 {
+		return false
+	}
+	switch lc.IP {
+	case "", "::", "0.0.0.0":
+		return true
+	default:
+		return false
+	}
+}
+
 // ListenerPolicyConfig specifies the policy rules for ctrld to filter incoming requests.
 type ListenerPolicyConfig struct {
 	Name                 string   `mapstructure:"name" toml:"name,omitempty"`
@@ -136,89 +262,118 @@ type Rule map[string][]string
 func (uc *UpstreamConfig) Init() {
 	if u, err := url.Parse(uc.Endpoint); err == nil {
 		uc.Domain = u.Host
+		switch uc.Type {
+		case ResolverTypeDOH, ResolverTypeDOH3:
+			uc.u = u
+		}
 	}
-	if uc.Domain != "" {
+	if uc.Domain == "" {
-		return
+		if !strings.Contains(uc.Endpoint, ":") {
+			uc.Domain = uc.Endpoint
+			uc.Endpoint = net.JoinHostPort(uc.Endpoint, defaultPortFor(uc.Type))
+		}
+		host, _, _ := net.SplitHostPort(uc.Endpoint)
+		uc.Domain = host
+		if net.ParseIP(uc.Domain) != nil {
+			uc.BootstrapIP = uc.Domain
+		}
 	}
+	if uc.IPStack == "" {
+		if uc.isControlD() {
+			uc.IPStack = IpStackSplit
+		} else {
+			uc.IPStack = IpStackBoth
+		}
+	}
+}
 
-	if !strings.Contains(uc.Endpoint, ":") {
+// VerifyDomain returns the domain name that could be resolved by the upstream endpoint.
-		uc.Domain = uc.Endpoint
+// It returns empty for non-ControlD upstream endpoint.
-		uc.Endpoint = net.JoinHostPort(uc.Endpoint, defaultPortFor(uc.Type))
+func (uc *UpstreamConfig) VerifyDomain() string {
+	domain := uc.Domain
+	if domain == "" {
+		if u, err := url.Parse(uc.Endpoint); err == nil {
+			domain = u.Hostname()
+		}
 	}
-	host, _, _ := net.SplitHostPort(uc.Endpoint)
+	for _, parent := range controldParentDomains {
-	uc.Domain = host
+		if dns.IsSubDomain(parent, domain) {
-	if net.ParseIP(uc.Domain) != nil {
+			return controldVerifiedDomain[parent]
-		uc.BootstrapIP = uc.Domain
+		}
 	}
+	return ""
+}
+
+// UpstreamSendClientInfo reports whether the upstream is
+// configured to send client info to Control D DNS server.
+//
+// Client info includes:
+//   - MAC
+//   - Lan IP
+//   - Hostname
+func (uc *UpstreamConfig) UpstreamSendClientInfo() bool {
+	if uc.SendClientInfo != nil {
+		return *uc.SendClientInfo
+	}
+	switch uc.Type {
+	case ResolverTypeDOH, ResolverTypeDOH3:
+		if uc.isControlD() {
+			return true
+		}
+	}
+	return false
+}
+
+// BootstrapIPs returns the bootstrap IPs list of upstreams.
+func (uc *UpstreamConfig) BootstrapIPs() []string {
+	return uc.bootstrapIPs
+}
+
+// SetCertPool sets the system cert pool used for TLS connections.
+func (uc *UpstreamConfig) SetCertPool(cp *x509.CertPool) {
+	uc.certPool = cp
 }
 
 // SetupBootstrapIP manually find all available IPs of the upstream.
 // The first usable IP will be used as bootstrap IP of the upstream.
 func (uc *UpstreamConfig) SetupBootstrapIP() {
-	bootstrapIP := func(record dns.RR) string {
+	uc.setupBootstrapIP(true)
-		switch ar := record.(type) {
+}
-		case *dns.A:
-			return ar.A.String()
-		case *dns.AAAA:
-			return ar.AAAA.String()
-		}
-		return ""
-	}
 
-	resolver := &osResolver{nameservers: availableNameservers()}
+// SetupBootstrapIP manually find all available IPs of the upstream.
-	resolver.nameservers = append([]string{net.JoinHostPort(bootstrapDNS, "53")}, resolver.nameservers...)
+// The first usable IP will be used as bootstrap IP of the upstream.
-	ProxyLog.Debug().Msgf("Resolving %q using bootstrap DNS %q", uc.Domain, resolver.nameservers)
+func (uc *UpstreamConfig) setupBootstrapIP(withBootstrapDNS bool) {
-	timeoutMs := 2000
+	b := backoff.NewBackoff("setupBootstrapIP", func(format string, args ...any) {}, 10*time.Second)
-	if uc.Timeout > 0 && uc.Timeout < timeoutMs {
+	isControlD := uc.isControlD()
-		timeoutMs = uc.Timeout
+	for {
-	}
+		uc.bootstrapIPs = lookupIP(uc.Domain, uc.Timeout, withBootstrapDNS)
-	do := func(dnsType uint16) {
+		// For ControlD upstream, the bootstrap IPs could not be RFC 1918 addresses,
-		ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeoutMs)*time.Millisecond)
+		// filtering them out here to prevent weird behavior.
-		defer cancel()
+		if isControlD {
-		m := new(dns.Msg)
+			n := 0
-		m.SetQuestion(uc.Domain+".", dnsType)
+			for _, ip := range uc.bootstrapIPs {
-		m.RecursionDesired = true
+				netIP := net.ParseIP(ip)
-
+				if netIP != nil && !netIP.IsPrivate() {
-		r, err := resolver.Resolve(ctx, m)
+					uc.bootstrapIPs[n] = ip
-		if err != nil {
+					n++
-			ProxyLog.Error().Err(err).Str("type", dns.TypeToString[dnsType]).Msgf("could not resolve domain %s for upstream", uc.Domain)
-			return
-		}
-		if r.Rcode != dns.RcodeSuccess {
-			ProxyLog.Error().Msgf("could not resolve domain return code: %d, upstream", r.Rcode)
-			return
-		}
-		if len(r.Answer) == 0 {
-			ProxyLog.Error().Msg("no answer from bootstrap DNS server")
-			return
-		}
-		for _, a := range r.Answer {
-			ip := bootstrapIP(a)
-			if ip == "" {
-				continue
-			}
-
-			// Storing the ip to uc.bootstrapIPs list, so it can be selected later
-			// when retrying failed request due to network stack changed.
-			uc.bootstrapIPs = append(uc.bootstrapIPs, ip)
-			if uc.BootstrapIP == "" {
-				// Remember what's the current IP in bootstrap IPs list,
-				// so we can select next one upon re-bootstrapping.
-				uc.nextBootstrapIP.Add(1)
-
-				// If this is an ipv6, and ipv6 is not available, don't use it as bootstrap ip.
-				if !ctrldnet.SupportsIPv6() && ctrldnet.IsIPv6(ip) {
-					continue
 				}
-				uc.BootstrapIP = ip
 			}
+			uc.bootstrapIPs = uc.bootstrapIPs[:n]
+		}
+		if len(uc.bootstrapIPs) > 0 {
+			break
+		}
+		ProxyLogger.Load().Warn().Msg("could not resolve bootstrap IPs, retrying...")
+		b.BackOff(context.Background(), errors.New("no bootstrap IPs"))
+	}
+	for _, ip := range uc.bootstrapIPs {
+		if ctrldnet.IsIPv6(ip) {
+			uc.bootstrapIPs6 = append(uc.bootstrapIPs6, ip)
+		} else {
+			uc.bootstrapIPs4 = append(uc.bootstrapIPs4, ip)
 		}
 	}
-	// Find all A, AAAA records of the upstream.
+	ProxyLogger.Load().Debug().Msgf("bootstrap IPs: %v", uc.bootstrapIPs)
-	for _, dnsType := range []uint16{dns.TypeAAAA, dns.TypeA} {
-		do(dnsType)
-	}
-	ProxyLog.Debug().Msgf("Bootstrap IPs: %v", uc.bootstrapIPs)
 }
 
 // ReBootstrap re-setup the bootstrap IP and the transport.
@@ -228,44 +383,13 @@ func (uc *UpstreamConfig) ReBootstrap() {
 	default:
 		return
 	}
-	_, _, _ = uc.g.Do("rebootstrap", func() (any, error) {
+	_, _, _ = uc.g.Do("ReBootstrap", func() (any, error) {
-		ProxyLog.Debug().Msg("re-bootstrapping upstream ip")
+		ProxyLogger.Load().Debug().Msg("re-bootstrapping upstream ip")
-		n := uint32(len(uc.bootstrapIPs))
+		uc.rebootstrap.Store(true)
-
-		timeoutMs := 1000
-		if uc.Timeout > 0 && uc.Timeout < timeoutMs {
-			timeoutMs = uc.Timeout
-		}
-		ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeoutMs)*time.Millisecond)
-		defer cancel()
-
-		hasIPv6 := ctrldnet.IPv6Available(ctx)
-		// Only attempt n times, because if there's no usable ip,
-		// the bootstrap ip will be kept as-is.
-		for i := uint32(0); i < n; i++ {
-			// Select the next ip in bootstrap ip list.
-			next := uc.nextBootstrapIP.Add(1)
-			ip := uc.bootstrapIPs[(next-1)%n]
-			if !hasIPv6 && ctrldnet.IsIPv6(ip) {
-				continue
-			}
-			uc.BootstrapIP = ip
-			break
-		}
-		uc.setupTransportWithoutPingUpstream()
 		return true, nil
 	})
 }
 
-func (uc *UpstreamConfig) setupTransportWithoutPingUpstream() {
-	switch uc.Type {
-	case ResolverTypeDOH:
-		uc.setupDOHTransportWithoutPingUpstream()
-	case ResolverTypeDOH3:
-		uc.setupDOH3TransportWithoutPingUpstream()
-	}
-}
-
 // SetupTransport initializes the network transport used to connect to upstream server.
 // For now, only DoH upstream is supported.
 func (uc *UpstreamConfig) SetupTransport() {
@@ -278,48 +402,176 @@ func (uc *UpstreamConfig) SetupTransport() {
 }
 
 func (uc *UpstreamConfig) setupDOHTransport() {
-	uc.setupDOHTransportWithoutPingUpstream()
+	switch uc.IPStack {
-	uc.pingUpstream()
+	case IpStackBoth, "":
+		uc.transport = uc.newDOHTransport(uc.bootstrapIPs)
+	case IpStackV4:
+		uc.transport = uc.newDOHTransport(uc.bootstrapIPs4)
+	case IpStackV6:
+		uc.transport = uc.newDOHTransport(uc.bootstrapIPs6)
+	case IpStackSplit:
+		uc.transport4 = uc.newDOHTransport(uc.bootstrapIPs4)
+		if hasIPv6() {
+			uc.transport6 = uc.newDOHTransport(uc.bootstrapIPs6)
+		} else {
+			uc.transport6 = uc.transport4
+		}
+		uc.transport = uc.newDOHTransport(uc.bootstrapIPs)
+	}
 }
 
-func (uc *UpstreamConfig) setupDOHTransportWithoutPingUpstream() {
+func (uc *UpstreamConfig) newDOHTransport(addrs []string) *http.Transport {
-	uc.transport = http.DefaultTransport.(*http.Transport).Clone()
+	transport := http.DefaultTransport.(*http.Transport).Clone()
-	uc.transport.IdleConnTimeout = 5 * time.Second
+	transport.MaxIdleConnsPerHost = 100
+	transport.TLSClientConfig = &tls.Config{
+		RootCAs:            uc.certPool,
+		ClientSessionCache: tls.NewLRUClientSessionCache(0),
+	}
 
 	dialerTimeoutMs := 2000
 	if uc.Timeout > 0 && uc.Timeout < dialerTimeoutMs {
 		dialerTimeoutMs = uc.Timeout
 	}
 	dialerTimeout := time.Duration(dialerTimeoutMs) * time.Millisecond
-	uc.transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
+	transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
-		dialer := &net.Dialer{
+		_, port, _ := net.SplitHostPort(addr)
-			Timeout:   dialerTimeout,
-			KeepAlive: dialerTimeout,
-		}
-		// if we have a bootstrap ip set, use it to avoid DNS lookup
 		if uc.BootstrapIP != "" {
-			if _, port, _ := net.SplitHostPort(addr); port != "" {
+			dialer := net.Dialer{Timeout: dialerTimeout, KeepAlive: dialerTimeout}
-				addr = net.JoinHostPort(uc.BootstrapIP, port)
+			addr := net.JoinHostPort(uc.BootstrapIP, port)
-			}
+			Log(ctx, ProxyLogger.Load().Debug(), "sending doh request to: %s", addr)
+			return dialer.DialContext(ctx, network, addr)
+		}
+		pd := &ctrldnet.ParallelDialer{}
+		pd.Timeout = dialerTimeout
+		pd.KeepAlive = dialerTimeout
+		dialAddrs := make([]string, len(addrs))
+		for i := range addrs {
+			dialAddrs[i] = net.JoinHostPort(addrs[i], port)
+		}
+		conn, err := pd.DialContext(ctx, network, dialAddrs)
+		if err != nil {
+			return nil, err
+		}
+		Log(ctx, ProxyLogger.Load().Debug(), "sending doh request to: %s", conn.RemoteAddr())
+		return conn, nil
+	}
+	runtime.SetFinalizer(transport, func(transport *http.Transport) {
+		transport.CloseIdleConnections()
+	})
+	return transport
+}
+
+// Ping warms up the connection to DoH/DoH3 upstream.
+func (uc *UpstreamConfig) Ping() {
+	switch uc.Type {
+	case ResolverTypeDOH, ResolverTypeDOH3:
+	default:
+		return
+	}
+
+	ping := func(t http.RoundTripper) {
+		if t == nil {
+			return
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		defer cancel()
+		req, _ := http.NewRequestWithContext(ctx, "HEAD", uc.Endpoint, nil)
+		resp, _ := t.RoundTrip(req)
+		if resp == nil {
+			return
+		}
+		defer resp.Body.Close()
+		_, _ = io.Copy(io.Discard, resp.Body)
+	}
+
+	for _, typ := range []uint16{dns.TypeA, dns.TypeAAAA} {
+		switch uc.Type {
+		case ResolverTypeDOH:
+			ping(uc.dohTransport(typ))
+		case ResolverTypeDOH3:
+			ping(uc.doh3Transport(typ))
 		}
-		Log(ctx, ProxyLog.Debug(), "sending doh request to: %s", addr)
-		return dialer.DialContext(ctx, network, addr)
 	}
 }
 
-func (uc *UpstreamConfig) pingUpstream() {
+func (uc *UpstreamConfig) isControlD() bool {
-	// Warming up the transport by querying a test packet.
+	domain := uc.Domain
-	dnsResolver, err := NewResolver(uc)
+	if domain == "" {
-	if err != nil {
+		if u, err := url.Parse(uc.Endpoint); err == nil {
-		ProxyLog.Error().Err(err).Msgf("failed to create resolver for upstream: %s", uc.Name)
+			domain = u.Hostname()
-		return
+		}
 	}
-	msg := new(dns.Msg)
+	for _, parent := range controldParentDomains {
-	msg.SetQuestion(".", dns.TypeNS)
+		if dns.IsSubDomain(parent, domain) {
-	msg.MsgHdr.RecursionDesired = true
+			return true
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		}
-	defer cancel()
+	}
-	_, _ = dnsResolver.Resolve(ctx, msg)
+	return false
+}
+
+func (uc *UpstreamConfig) dohTransport(dnsType uint16) http.RoundTripper {
+	uc.transportOnce.Do(func() {
+		uc.SetupTransport()
+	})
+	if uc.rebootstrap.CompareAndSwap(true, false) {
+		uc.SetupTransport()
+	}
+	switch uc.IPStack {
+	case IpStackBoth, IpStackV4, IpStackV6:
+		return uc.transport
+	case IpStackSplit:
+		switch dnsType {
+		case dns.TypeA:
+			return uc.transport4
+		default:
+			return uc.transport6
+		}
+	}
+	return uc.transport
+}
+
+func (uc *UpstreamConfig) bootstrapIPForDNSType(dnsType uint16) string {
+	switch uc.IPStack {
+	case IpStackBoth:
+		return pick(uc.bootstrapIPs)
+	case IpStackV4:
+		return pick(uc.bootstrapIPs4)
+	case IpStackV6:
+		return pick(uc.bootstrapIPs6)
+	case IpStackSplit:
+		switch dnsType {
+		case dns.TypeA:
+			return pick(uc.bootstrapIPs4)
+		default:
+			if hasIPv6() {
+				return pick(uc.bootstrapIPs6)
+			}
+			return pick(uc.bootstrapIPs4)
+		}
+	}
+	return pick(uc.bootstrapIPs)
+}
+
+func (uc *UpstreamConfig) netForDNSType(dnsType uint16) (string, string) {
+	switch uc.IPStack {
+	case IpStackBoth:
+		return "tcp-tls", "udp"
+	case IpStackV4:
+		return "tcp4-tls", "udp4"
+	case IpStackV6:
+		return "tcp6-tls", "udp6"
+	case IpStackSplit:
+		switch dnsType {
+		case dns.TypeA:
+			return "tcp4-tls", "udp4"
+		default:
+			if hasIPv6() {
+				return "tcp6-tls", "udp6"
+			}
+			return "tcp4-tls", "udp4"
+		}
+	}
+	return "tcp-tls", "udp"
 }
 
 // Init initialized necessary values for an ListenerConfig.
@@ -335,6 +587,9 @@ func (lc *ListenerConfig) Init() {
 // ValidateConfig validates the given config.
 func ValidateConfig(validate *validator.Validate, cfg *Config) error {
 	_ = validate.RegisterValidation("dnsrcode", validateDnsRcode)
+	_ = validate.RegisterValidation("ipstack", validateIpStack)
+	_ = validate.RegisterValidation("iporempty", validateIpOrEmpty)
+	validate.RegisterStructValidation(upstreamConfigStructLevelValidation, UpstreamConfig{})
 	return validate.Struct(cfg)
 }
 
@@ -342,6 +597,49 @@ func validateDnsRcode(fl validator.FieldLevel) bool {
 	return dnsrcode.FromString(fl.Field().String()) != -1
 }
 
+func validateIpStack(fl validator.FieldLevel) bool {
+	switch fl.Field().String() {
+	case IpStackBoth, IpStackV4, IpStackV6, IpStackSplit, "":
+		return true
+	default:
+		return false
+	}
+}
+
+func validateIpOrEmpty(fl validator.FieldLevel) bool {
+	val := fl.Field().String()
+	if val == "" {
+		return true
+	}
+	return net.ParseIP(val) != nil
+}
+
+func upstreamConfigStructLevelValidation(sl validator.StructLevel) {
+	uc := sl.Current().Addr().Interface().(*UpstreamConfig)
+	if uc.Type == ResolverTypeOS {
+		return
+	}
+
+	// Endpoint is required for non os resolver.
+	if uc.Endpoint == "" {
+		sl.ReportError(uc.Endpoint, "endpoint", "Endpoint", "required_unless", "")
+		return
+	}
+
+	// DoH/DoH3 requires endpoint is an HTTP url.
+	if uc.Type == ResolverTypeDOH || uc.Type == ResolverTypeDOH3 {
+		u, err := url.Parse(uc.Endpoint)
+		if err != nil || u.Host == "" {
+			sl.ReportError(uc.Endpoint, "endpoint", "Endpoint", "http_url", "")
+			return
+		}
+		if u.Scheme != "http" && u.Scheme != "https" {
+			sl.ReportError(uc.Endpoint, "endpoint", "Endpoint", "http_url", "")
+			return
+		}
+	}
+}
+
 func defaultPortFor(typ string) string {
 	switch typ {
 	case ResolverTypeDOH, ResolverTypeDOH3:
@@ -354,17 +652,30 @@ func defaultPortFor(typ string) string {
 	return "53"
 }
 
-func availableNameservers() []string {
+// ResolverTypeFromEndpoint tries guessing the resolver type with a given endpoint
-	nss := nameservers()
+// using following rules:
-	n := 0
+//
-	for _, ns := range nss {
+// - If endpoint is an IP address ->  ResolverTypeLegacy
-		ip, _, _ := net.SplitHostPort(ns)
+// - If endpoint starts with "https://" -> ResolverTypeDOH
-		// skipping invalid entry or ipv6 nameserver if ipv6 not available.
+// - If endpoint starts with "quic://" -> ResolverTypeDOQ
-		if ip == "" || (ctrldnet.IsIPv6(ip) && !ctrldnet.SupportsIPv6()) {
+// - For anything else -> ResolverTypeDOT
-			continue
+func ResolverTypeFromEndpoint(endpoint string) string {
-		}
+	switch {
-		nss[n] = ns
+	case strings.HasPrefix(endpoint, "https://"):
-		n++
+		return ResolverTypeDOH
+	case strings.HasPrefix(endpoint, "quic://"):
+		return ResolverTypeDOQ
 	}
-	return nss[:n]
+	host := endpoint
+	if strings.Contains(endpoint, ":") {
+		host, _, _ = net.SplitHostPort(host)
+	}
+	if ip := net.ParseIP(host); ip != nil {
+		return ResolverTypeLegacy
+	}
+	return ResolverTypeDOT
+}
+
+func pick(s []string) string {
+	return s[rand.Intn(len(s))]
 }

config_internal_test.go

@@ -0,0 +1,283 @@
+package ctrld
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestUpstreamConfig_SetupBootstrapIP(t *testing.T) {
+	uc := &UpstreamConfig{
+		Name:     "test",
+		Type:     ResolverTypeDOH,
+		Endpoint: "https://freedns.controld.com/p2",
+		Timeout:  5000,
+	}
+	uc.Init()
+	uc.setupBootstrapIP(false)
+	if len(uc.bootstrapIPs) == 0 {
+		t.Log(nameservers())
+		t.Fatal("could not bootstrap ip without bootstrap DNS")
+	}
+	t.Log(uc)
+}
+
+func TestUpstreamConfig_Init(t *testing.T) {
+	u1, _ := url.Parse("https://example.com")
+	u2, _ := url.Parse("https://example.com?k=v")
+	tests := []struct {
+		name     string
+		uc       *UpstreamConfig
+		expected *UpstreamConfig
+	}{
+		{
+			"doh+doh3",
+			&UpstreamConfig{
+				Name:        "doh",
+				Type:        "doh",
+				Endpoint:    "https://example.com",
+				BootstrapIP: "",
+				Domain:      "",
+				Timeout:     0,
+			},
+			&UpstreamConfig{
+				Name:        "doh",
+				Type:        "doh",
+				Endpoint:    "https://example.com",
+				BootstrapIP: "",
+				Domain:      "example.com",
+				Timeout:     0,
+				IPStack:     IpStackBoth,
+				u:           u1,
+			},
+		},
+		{
+			"doh+doh3 with query param",
+			&UpstreamConfig{
+				Name:        "doh",
+				Type:        "doh",
+				Endpoint:    "https://example.com?k=v",
+				BootstrapIP: "",
+				Domain:      "",
+				Timeout:     0,
+			},
+			&UpstreamConfig{
+				Name:        "doh",
+				Type:        "doh",
+				Endpoint:    "https://example.com?k=v",
+				BootstrapIP: "",
+				Domain:      "example.com",
+				Timeout:     0,
+				IPStack:     IpStackBoth,
+				u:           u2,
+			},
+		},
+		{
+			"dot+doq",
+			&UpstreamConfig{
+				Name:        "dot",
+				Type:        "dot",
+				Endpoint:    "freedns.controld.com:8853",
+				BootstrapIP: "",
+				Domain:      "",
+				Timeout:     0,
+			},
+			&UpstreamConfig{
+				Name:        "dot",
+				Type:        "dot",
+				Endpoint:    "freedns.controld.com:8853",
+				BootstrapIP: "",
+				Domain:      "freedns.controld.com",
+				Timeout:     0,
+				IPStack:     IpStackSplit,
+			},
+		},
+		{
+			"dot+doq without port",
+			&UpstreamConfig{
+				Name:        "dot",
+				Type:        "dot",
+				Endpoint:    "freedns.controld.com",
+				BootstrapIP: "",
+				Domain:      "",
+				Timeout:     0,
+				IPStack:     IpStackSplit,
+			},
+			&UpstreamConfig{
+				Name:        "dot",
+				Type:        "dot",
+				Endpoint:    "freedns.controld.com:853",
+				BootstrapIP: "",
+				Domain:      "freedns.controld.com",
+				Timeout:     0,
+				IPStack:     IpStackSplit,
+			},
+		},
+		{
+			"legacy",
+			&UpstreamConfig{
+				Name:        "legacy",
+				Type:        "legacy",
+				Endpoint:    "1.2.3.4:53",
+				BootstrapIP: "",
+				Domain:      "",
+				Timeout:     0,
+			},
+			&UpstreamConfig{
+				Name:        "legacy",
+				Type:        "legacy",
+				Endpoint:    "1.2.3.4:53",
+				BootstrapIP: "1.2.3.4",
+				Domain:      "1.2.3.4",
+				Timeout:     0,
+				IPStack:     IpStackBoth,
+			},
+		},
+		{
+			"legacy without port",
+			&UpstreamConfig{
+				Name:        "legacy",
+				Type:        "legacy",
+				Endpoint:    "1.2.3.4",
+				BootstrapIP: "",
+				Domain:      "",
+				Timeout:     0,
+			},
+			&UpstreamConfig{
+				Name:        "legacy",
+				Type:        "legacy",
+				Endpoint:    "1.2.3.4:53",
+				BootstrapIP: "1.2.3.4",
+				Domain:      "1.2.3.4",
+				Timeout:     0,
+				IPStack:     IpStackBoth,
+			},
+		},
+		{
+			"doh+doh3 with send client info set",
+			&UpstreamConfig{
+				Name:           "doh",
+				Type:           "doh",
+				Endpoint:       "https://example.com?k=v",
+				BootstrapIP:    "",
+				Domain:         "",
+				Timeout:        0,
+				SendClientInfo: ptrBool(false),
+				IPStack:        IpStackBoth,
+			},
+			&UpstreamConfig{
+				Name:           "doh",
+				Type:           "doh",
+				Endpoint:       "https://example.com?k=v",
+				BootstrapIP:    "",
+				Domain:         "example.com",
+				Timeout:        0,
+				SendClientInfo: ptrBool(false),
+				IPStack:        IpStackBoth,
+				u:              u2,
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			tc.uc.Init()
+			assert.Equal(t, tc.expected, tc.uc)
+		})
+	}
+}
+
+func TestUpstreamConfig_VerifyDomain(t *testing.T) {
+	tests := []struct {
+		name         string
+		uc           *UpstreamConfig
+		verifyDomain string
+	}{
+		{
+			controlDComDomain,
+			&UpstreamConfig{Endpoint: "https://freedns.controld.com/p2"},
+			controldVerifiedDomain[controlDComDomain],
+		},
+		{
+			controlDDevDomain,
+			&UpstreamConfig{Endpoint: "https://freedns.controld.dev/p2"},
+			controldVerifiedDomain[controlDDevDomain],
+		},
+		{
+			"non-ControlD upstream",
+			&UpstreamConfig{Endpoint: "https://dns.google/dns-query"},
+			"",
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			if got := tc.uc.VerifyDomain(); got != tc.verifyDomain {
+				t.Errorf("unexpected verify domain, want: %q, got: %q", tc.verifyDomain, got)
+			}
+		})
+	}
+}
+
+func TestUpstreamConfig_UpstreamSendClientInfo(t *testing.T) {
+	tests := []struct {
+		name           string
+		uc             *UpstreamConfig
+		sendClientInfo bool
+	}{
+		{
+			"default with controld upstream DoH",
+			&UpstreamConfig{Endpoint: "https://freedns.controld.com/p2", Type: ResolverTypeDOH},
+			true,
+		},
+		{
+			"default with controld upstream DoH3",
+			&UpstreamConfig{Endpoint: "https://freedns.controld.com/p2", Type: ResolverTypeDOH3},
+			true,
+		},
+		{
+			"default with non-ControlD upstream",
+			&UpstreamConfig{Endpoint: "https://dns.google/dns-query", Type: ResolverTypeDOH},
+			false,
+		},
+		{
+			"set false with controld upstream",
+			&UpstreamConfig{Endpoint: "https://freedns.controld.com/p2", Type: ResolverTypeDOH, SendClientInfo: ptrBool(false)},
+			false,
+		},
+		{
+			"set true with controld upstream",
+			&UpstreamConfig{Endpoint: "https://freedns.controld.com/p2", SendClientInfo: ptrBool(true)},
+			true,
+		},
+		{
+			"set false with non-ControlD upstream",
+			&UpstreamConfig{Endpoint: "https://dns.google/dns-query", SendClientInfo: ptrBool(false)},
+			false,
+		},
+		{
+			"set true with non-ControlD upstream",
+			&UpstreamConfig{Endpoint: "https://dns.google/dns-query", Type: ResolverTypeDOH, SendClientInfo: ptrBool(true)},
+			true,
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			if got := tc.uc.UpstreamSendClientInfo(); got != tc.sendClientInfo {
+				t.Errorf("unexpected result, want: %v, got: %v", tc.sendClientInfo, got)
+			}
+		})
+	}
+}
+
+func ptrBool(b bool) *bool {
+	return &b
+}

config_quic.go

@@ -5,40 +5,150 @@ package ctrld
 import (
 	"context"
 	"crypto/tls"
+	"errors"
 	"net"
+	"net/http"
+	"sync"
+	"time"
 
+	"github.com/miekg/dns"
 	"github.com/quic-go/quic-go"
 	"github.com/quic-go/quic-go/http3"
+
+	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
 )
 
 func (uc *UpstreamConfig) setupDOH3Transport() {
-	uc.setupDOH3TransportWithoutPingUpstream()
+	switch uc.IPStack {
-	uc.pingUpstream()
+	case IpStackBoth, "":
+		uc.http3RoundTripper = uc.newDOH3Transport(uc.bootstrapIPs)
+	case IpStackV4:
+		uc.http3RoundTripper = uc.newDOH3Transport(uc.bootstrapIPs4)
+	case IpStackV6:
+		uc.http3RoundTripper = uc.newDOH3Transport(uc.bootstrapIPs6)
+	case IpStackSplit:
+		uc.http3RoundTripper4 = uc.newDOH3Transport(uc.bootstrapIPs4)
+		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		defer cancel()
+		if ctrldnet.IPv6Available(ctx) {
+			uc.http3RoundTripper6 = uc.newDOH3Transport(uc.bootstrapIPs6)
+		} else {
+			uc.http3RoundTripper6 = uc.http3RoundTripper4
+		}
+		uc.http3RoundTripper = uc.newDOH3Transport(uc.bootstrapIPs)
+	}
 }
 
-func (uc *UpstreamConfig) setupDOH3TransportWithoutPingUpstream() {
+func (uc *UpstreamConfig) newDOH3Transport(addrs []string) http.RoundTripper {
 	rt := &http3.RoundTripper{}
+	rt.TLSClientConfig = &tls.Config{RootCAs: uc.certPool}
 	rt.Dial = func(ctx context.Context, addr string, tlsCfg *tls.Config, cfg *quic.Config) (quic.EarlyConnection, error) {
-		host := addr
+		domain := addr
-		ProxyLog.Debug().Msgf("debug dial context D0H3 %s - %s", addr, bootstrapDNS)
+		_, port, _ := net.SplitHostPort(addr)
 		// if we have a bootstrap ip set, use it to avoid DNS lookup
 		if uc.BootstrapIP != "" {
-			if _, port, _ := net.SplitHostPort(addr); port != "" {
+			addr = net.JoinHostPort(uc.BootstrapIP, port)
-				addr = net.JoinHostPort(uc.BootstrapIP, port)
+			ProxyLogger.Load().Debug().Msgf("sending doh3 request to: %s", addr)
+			udpConn, err := net.ListenUDP("udp", nil)
+			if err != nil {
+				return nil, err
 			}
-			ProxyLog.Debug().Msgf("sending doh3 request to: %s", addr)
+			remoteAddr, err := net.ResolveUDPAddr("udp", addr)
+			if err != nil {
+				return nil, err
+			}
+			return quic.DialEarlyContext(ctx, udpConn, remoteAddr, domain, tlsCfg, cfg)
 		}
-		remoteAddr, err := net.ResolveUDPAddr("udp", addr)
+		dialAddrs := make([]string, len(addrs))
+		for i := range addrs {
+			dialAddrs[i] = net.JoinHostPort(addrs[i], port)
+		}
+		pd := &quicParallelDialer{}
+		conn, err := pd.Dial(ctx, domain, dialAddrs, tlsCfg, cfg)
 		if err != nil {
 			return nil, err
 		}
+		ProxyLogger.Load().Debug().Msgf("sending doh3 request to: %s", conn.RemoteAddr())
+		return conn, err
+	}
+	return rt
+}
 
-		udpConn, err := net.ListenUDP("udp", nil)
+func (uc *UpstreamConfig) doh3Transport(dnsType uint16) http.RoundTripper {
-		if err != nil {
+	uc.transportOnce.Do(func() {
-			return nil, err
+		uc.SetupTransport()
+	})
+	if uc.rebootstrap.CompareAndSwap(true, false) {
+		uc.SetupTransport()
+	}
+	switch uc.IPStack {
+	case IpStackBoth, IpStackV4, IpStackV6:
+		return uc.http3RoundTripper
+	case IpStackSplit:
+		switch dnsType {
+		case dns.TypeA:
+			return uc.http3RoundTripper4
+		default:
+			return uc.http3RoundTripper6
 		}
-		return quic.DialEarlyContext(ctx, udpConn, remoteAddr, host, tlsCfg, cfg)
+	}
+	return uc.http3RoundTripper
+}
+
+// Putting the code for quic parallel dialer here:
+//
+//   - quic dialer is different with net.Dialer
+//   - simplification for quic free version
+type parallelDialerResult struct {
+	conn quic.EarlyConnection
+	err  error
+}
+
+type quicParallelDialer struct{}
+
+// Dial performs parallel dialing to the given address list.
+func (d *quicParallelDialer) Dial(ctx context.Context, domain string, addrs []string, tlsCfg *tls.Config, cfg *quic.Config) (quic.EarlyConnection, error) {
+	if len(addrs) == 0 {
+		return nil, errors.New("empty addresses")
+	}
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	ch := make(chan *parallelDialerResult, len(addrs))
+	var wg sync.WaitGroup
+	wg.Add(len(addrs))
+	go func() {
+		wg.Wait()
+		close(ch)
+	}()
+
+	udpConn, err := net.ListenUDP("udp", nil)
+	if err != nil {
+		return nil, err
 	}
 
-	uc.http3RoundTripper = rt
+	for _, addr := range addrs {
+		go func(addr string) {
+			defer wg.Done()
+			remoteAddr, err := net.ResolveUDPAddr("udp", addr)
+			if err != nil {
+				ch <- &parallelDialerResult{conn: nil, err: err}
+				return
+			}
+
+			conn, err := quic.DialEarlyContext(ctx, udpConn, remoteAddr, domain, tlsCfg, cfg)
+			ch <- &parallelDialerResult{conn: conn, err: err}
+		}(addr)
+	}
+
+	errs := make([]error, 0, len(addrs))
+	for res := range ch {
+		if res.err == nil {
+			cancel()
+			return res.conn, res.err
+		}
+		errs = append(errs, res.err)
+	}
+
+	return nil, errors.Join(errs...)
 }

config_quic_free.go

@@ -2,6 +2,8 @@
 
 package ctrld
 
+import "net/http"
+
 func (uc *UpstreamConfig) setupDOH3Transport() {}
 
-func (uc *UpstreamConfig) setupDOH3TransportWithoutPingUpstream() {}
+func (uc *UpstreamConfig) doh3Transport(dnsType uint16) http.RoundTripper { return nil }

config_test.go

@@ -1,6 +1,8 @@
 package ctrld_test
 
 import (
+	"os"
+	"strings"
 	"testing"
 
 	"github.com/go-playground/validator/v10"
@@ -24,10 +26,12 @@ func TestLoadConfig(t *testing.T) {
 	assert.Contains(t, cfg.Network, "0")
 	assert.Contains(t, cfg.Network, "1")
 
-	assert.Len(t, cfg.Upstream, 3)
+	assert.Len(t, cfg.Upstream, 4)
 	assert.Contains(t, cfg.Upstream, "0")
 	assert.Contains(t, cfg.Upstream, "1")
 	assert.Contains(t, cfg.Upstream, "2")
+	assert.Contains(t, cfg.Upstream, "3")
+	assert.NotNil(t, cfg.Upstream["3"].SendClientInfo)
 
 	assert.Len(t, cfg.Listener, 2)
 	assert.Contains(t, cfg.Listener, "0")
@@ -42,6 +46,8 @@ func TestLoadConfig(t *testing.T) {
 	assert.Len(t, cfg.Listener["0"].Policy.Rules, 2)
 	assert.Contains(t, cfg.Listener["0"].Policy.Rules[0], "*.ru")
 	assert.Contains(t, cfg.Listener["0"].Policy.Rules[1], "*.local.host")
+
+	assert.True(t, cfg.HasUpstreamSendClientInfo())
 }
 
 func TestLoadDefaultConfig(t *testing.T) {
@@ -52,6 +58,20 @@ func TestLoadDefaultConfig(t *testing.T) {
 	assert.Len(t, cfg.Upstream, 2)
 }
 
+func TestConfigOverride(t *testing.T) {
+	v := viper.NewWithOptions(viper.KeyDelimiter("::"))
+	ctrld.InitConfig(v, "test_load_config")
+	v.SetConfigType("toml")
+	require.NoError(t, v.ReadConfig(strings.NewReader(testhelper.SampleConfigStr(t))))
+	cfg := ctrld.Config{Listener: map[string]*ctrld.ListenerConfig{
+		"0": {IP: "127.0.0.1", Port: 53},
+	}}
+	require.NoError(t, v.Unmarshal(&cfg))
+
+	assert.Equal(t, "10.10.42.69", cfg.Listener["1"].IP)
+	assert.Equal(t, 1337, cfg.Listener["1"].Port)
+}
+
 func TestConfigValidation(t *testing.T) {
 	tests := []struct {
 		name    string
@@ -61,6 +81,7 @@ func TestConfigValidation(t *testing.T) {
 		{"invalid Config", &ctrld.Config{}, true},
 		{"default Config", defaultConfig(t), false},
 		{"sample Config", testhelper.SampleConfig(t), false},
+		{"empty listener IP", emptyListenerIP(t), false},
 		{"invalid cidr", invalidNetworkConfig(t), true},
 		{"invalid upstream type", invalidUpstreamType(t), true},
 		{"invalid upstream timeout", invalidUpstreamTimeout(t), true},
@@ -70,6 +91,11 @@ func TestConfigValidation(t *testing.T) {
 		{"os upstream", configWithOsUpstream(t), false},
 		{"invalid rules", configWithInvalidRules(t), true},
 		{"invalid dns rcodes", configWithInvalidRcodes(t), true},
+		{"invalid max concurrent requests", configWithInvalidMaxConcurrentRequests(t), true},
+		{"non-existed lease file", configWithNonExistedLeaseFile(t), true},
+		{"lease file format required if lease file exist", configWithExistedLeaseFile(t), true},
+		{"invalid lease file format", configWithInvalidLeaseFileFormat(t), true},
+		{"invalid doh/doh3 endpoint", configWithInvalidDoHEndpoint(t), true},
 	}
 
 	for _, tc := range tests {
@@ -130,9 +156,15 @@ func invalidListenerIP(t *testing.T) *ctrld.Config {
 	return cfg
 }
 
+func emptyListenerIP(t *testing.T) *ctrld.Config {
+	cfg := defaultConfig(t)
+	cfg.Listener["0"].IP = ""
+	return cfg
+}
+
 func invalidListenerPort(t *testing.T) *ctrld.Config {
 	cfg := defaultConfig(t)
-	cfg.Listener["0"].Port = 0
+	cfg.Listener["0"].Port = -1
 	return cfg
 }
 
@@ -166,115 +198,38 @@ func configWithInvalidRcodes(t *testing.T) *ctrld.Config {
 	return cfg
 }
 
-func TestUpstreamConfig_Init(t *testing.T) {
+func configWithInvalidMaxConcurrentRequests(t *testing.T) *ctrld.Config {
-	tests := []struct {
+	cfg := defaultConfig(t)
-		name     string
+	n := -1
-		uc       *ctrld.UpstreamConfig
+	cfg.Service.MaxConcurrentRequests = &n
-		expected *ctrld.UpstreamConfig
+	return cfg
-	}{
+}
-		{
+
-			"doh+doh3",
+func configWithNonExistedLeaseFile(t *testing.T) *ctrld.Config {
-			&ctrld.UpstreamConfig{
+	cfg := defaultConfig(t)
-				Name:        "doh",
+	cfg.Service.DHCPLeaseFile = "non-existed"
-				Type:        "doh",
+	return cfg
-				Endpoint:    "https://example.com",
+}
-				BootstrapIP: "",
+
-				Domain:      "",
+func configWithExistedLeaseFile(t *testing.T) *ctrld.Config {
-				Timeout:     0,
+	cfg := defaultConfig(t)
-			},
+	exe, err := os.Executable()
-			&ctrld.UpstreamConfig{
+	if err != nil {
-				Name:        "doh",
+		t.Fatal(err)
-				Type:        "doh",
+	}
-				Endpoint:    "https://example.com",
+	cfg.Service.DHCPLeaseFile = exe
-				BootstrapIP: "",
+	return cfg
-				Domain:      "example.com",
+}
-				Timeout:     0,
+
-			},
+func configWithInvalidLeaseFileFormat(t *testing.T) *ctrld.Config {
-		},
+	cfg := defaultConfig(t)
-		{
+	cfg.Service.DHCPLeaseFileFormat = "invalid"
-			"dot+doq",
+	return cfg
-			&ctrld.UpstreamConfig{
+}
-				Name:        "dot",
+
-				Type:        "dot",
+func configWithInvalidDoHEndpoint(t *testing.T) *ctrld.Config {
-				Endpoint:    "freedns.controld.com:8853",
+	cfg := defaultConfig(t)
-				BootstrapIP: "",
+	cfg.Upstream["0"].Endpoint = "1.1.1.1"
-				Domain:      "",
+	cfg.Upstream["0"].Type = ctrld.ResolverTypeDOH
-				Timeout:     0,
+	return cfg
-			},
-			&ctrld.UpstreamConfig{
-				Name:        "dot",
-				Type:        "dot",
-				Endpoint:    "freedns.controld.com:8853",
-				BootstrapIP: "",
-				Domain:      "freedns.controld.com",
-				Timeout:     0,
-			},
-		},
-		{
-			"dot+doq without port",
-			&ctrld.UpstreamConfig{
-				Name:        "dot",
-				Type:        "dot",
-				Endpoint:    "freedns.controld.com",
-				BootstrapIP: "",
-				Domain:      "",
-				Timeout:     0,
-			},
-			&ctrld.UpstreamConfig{
-				Name:        "dot",
-				Type:        "dot",
-				Endpoint:    "freedns.controld.com:853",
-				BootstrapIP: "",
-				Domain:      "freedns.controld.com",
-				Timeout:     0,
-			},
-		},
-		{
-			"legacy",
-			&ctrld.UpstreamConfig{
-				Name:        "legacy",
-				Type:        "legacy",
-				Endpoint:    "1.2.3.4:53",
-				BootstrapIP: "",
-				Domain:      "",
-				Timeout:     0,
-			},
-			&ctrld.UpstreamConfig{
-				Name:        "legacy",
-				Type:        "legacy",
-				Endpoint:    "1.2.3.4:53",
-				BootstrapIP: "1.2.3.4",
-				Domain:      "1.2.3.4",
-				Timeout:     0,
-			},
-		},
-		{
-			"legacy without port",
-			&ctrld.UpstreamConfig{
-				Name:        "legacy",
-				Type:        "legacy",
-				Endpoint:    "1.2.3.4",
-				BootstrapIP: "",
-				Domain:      "",
-				Timeout:     0,
-			},
-			&ctrld.UpstreamConfig{
-				Name:        "legacy",
-				Type:        "legacy",
-				Endpoint:    "1.2.3.4:53",
-				BootstrapIP: "1.2.3.4",
-				Domain:      "1.2.3.4",
-				Timeout:     0,
-			},
-		},
-	}
-
-	for _, tc := range tests {
-		tc := tc
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-			tc.uc.Init()
-			assert.Equal(t, tc.expected, tc.uc)
-		})
-	}
 }

docs/config.md

@@ -14,10 +14,15 @@ The config file allows for advanced configuration of the `ctrld` utility to cove
 
 
 ## Config Location
-`ctrld` uses [TOML](toml_link) format for its configuration file. Default configuration file is `config.toml` found in following order:
+`ctrld` uses [TOML](toml_link) format for its configuration file. Default configuration file is `ctrld.toml` found in following order:
 
- - `$HOME/.ctrld`
+ - `/etc/controld` on *nix.
- - Current directory
+ - User's home directory on Windows.
+ - Same directory with `ctrld` binary on these routers:
+   - `ddwrt`
+   - `merlin`
+   - `freshtomato`
+ - Current directory.
 
 The user can choose to override default value using command line `--config` or `-c`:
 
@@ -38,6 +43,8 @@ if it's existed.
     log_path = ""
     cache_enable = true
     cache_size = 4096
+    cache_ttl_override = 60
+    cache_serve_stale = true
 
 [network.0]
     cidrs = ["0.0.0.0/0"]
@@ -53,6 +60,7 @@ if it's existed.
     name = "Control D - Anti-Malware"
     timeout = 5000
     type = "doh"
+    ip_stack = "both"
 
 [upstream.1]
     bootstrap_ip = "76.76.2.11"
@@ -60,6 +68,7 @@ if it's existed.
     name = "Control D - No Ads"
     timeout = 5000
     type = "doq"
+    ip_stack = "split"
 
 [upstream.2]
     bootstrap_ip = "76.76.2.22"
@@ -67,6 +76,7 @@ if it's existed.
     name = "Control D - Private"
     timeout = 5000
     type = "dot"
+    ip_stack = "v4"
 
 [listener.0]
     ip = "127.0.0.1"
@@ -104,8 +114,8 @@ Logging level you wish to enable.
 
  - Type: string
  - Required: no
- - Valid values: `debug`, `info`, `warn`, `error`, `fatal`, `panic`
+ - Valid values: `debug`, `info`, `warn`, `notice`, `error`, `fatal`, `panic`
- - Default: `info`
+ - Default: `notice`
 
 
 ### log_path
@@ -113,12 +123,14 @@ Relative or absolute path of the log file.
 
 - Type: string
 - Required: no
+- Default: ""
 
 ### cache_enable
 When `cache_enable = true`, all resolved DNS query responses will be cached for duration of the upstream record TTLs.
 
 - Type: boolean
 - Required: no
+- Default: false
 
 ### cache_size
 The number of cached records, must be a positive integer. Tweaking this value with care depends on your available RAM. 
@@ -128,29 +140,73 @@ An invalid `cache_size` value will disable the cache, regardless of `cache_enabl
 
 - Type: int
 - Required: no
+- Default: 4096
 
 ### cache_ttl_override
 When `cache_ttl_override` is set to a positive value (in seconds), TTLs are overridden to this value and cached for this long.
 
 - Type: int
 - Required: no
+- Default: 0
 
 ### cache_serve_stale
 When `cache_serve_stale = true`, in cases of upstream failures (upstreams not reachable), `ctrld` will keep serving
 stale cached records (regardless of their TTLs) until upstream comes online.
 
-The above config will look like this at query time.
+- Type: boolean
+- Required: no
+- Default: false
 
-```
+### max_concurrent_requests
-2022-11-14T22:18:53.808 INF Setting bootstrap IP for upstream.0 bootstrap_ip=76.76.2.11
+The number of concurrent requests that will be handled, must be a non-negative integer. 
-2022-11-14T22:18:53.808 INF Starting DNS server on listener.0: 127.0.0.1:53
+Tweaking this value depends on the capacity of your system.
-2022-11-14T22:18:56.381 DBG [9fd5d3] 127.0.0.1:53978 -> listener.0: 127.0.0.1:53: received query: verify.controld.com
+
-2022-11-14T22:18:56.381 INF [9fd5d3] no policy, no network, no rule -> [upstream.0]
+- Type: number
-2022-11-14T22:18:56.381 DBG [9fd5d3] sending query to upstream.0: Control D - DOH Free
+- Required: no
-2022-11-14T22:18:56.381 DBG [9fd5d3] debug dial context freedns.controld.com:443 - tcp - 76.76.2.0
+- Default: 256
-2022-11-14T22:18:56.381 DBG [9fd5d3] sending doh request to: 76.76.2.11:443
+
-2022-11-14T22:18:56.420 DBG [9fd5d3] received response of 118 bytes in 39.662597ms
+### discover_mdns
-```
+Perform LAN client discovery using mDNS. This will spawn a listener on port 5353. 
+
+- Type: boolean
+- Required: no
+- Default: true
+
+### discover_arp
+Perform LAN client discovery using ARP.  
+
+- Type: boolean
+- Required: no
+- Default: true
+
+### discover_dhcp
+Perform LAN client discovery using DHCP leases files. Common file locations are auto-discovered.  
+
+- Type: boolean
+- Required: no
+- Default: true
+
+### discover_ptr
+Perform LAN client discovery using PTR queries.  
+
+- Type: boolean
+- Required: no
+- Default: true
+
+### dhcp_lease_file_path
+Relative or absolute path to a custom DHCP leases file location. 
+
+- Type: string
+- Required: no
+- Default: ""
+
+### dhcp_lease_file_format
+DHCP leases file format. 
+
+- Type: string
+- Required: no
+- Valid values: `dnsmasq`, `isc-dhcp`
+- Default: ""
 
 ## Upstream
 The `[upstream]` section specifies the DNS upstream servers that `ctrld` will forward DNS requests to.
@@ -162,6 +218,7 @@ The `[upstream]` section specifies the DNS upstream servers that `ctrld` will fo
   name = "Control D - DOH"
   timeout = 5000
   type = "doh"
+  ip_stack = "split"
   
 [upstream.1]
   bootstrap_ip = ""
@@ -169,6 +226,7 @@ The `[upstream]` section specifies the DNS upstream servers that `ctrld` will fo
   name = "Control D - DOH3"
   timeout = 5000
   type = "doh3"
+  ip_stack = "both"
   
 [upstream.2]
   bootstrap_ip = ""
@@ -176,6 +234,7 @@ The `[upstream]` section specifies the DNS upstream servers that `ctrld` will fo
   name = "Controld D - DOT"
   timeout = 5000
   type = "dot"
+  ip_stack = "v4"
   
 [upstream.3]
   bootstrap_ip = ""
@@ -183,6 +242,7 @@ The `[upstream]` section specifies the DNS upstream servers that `ctrld` will fo
   name = "Controld D - DOT"
   timeout = 5000
   type = "doq"
+  ip_stack = "v6"
   
 [upstream.4]
   bootstrap_ip = ""
@@ -190,6 +250,7 @@ The `[upstream]` section specifies the DNS upstream servers that `ctrld` will fo
   name = "Control D - Ad Blocking"
   timeout = 5000
   type = "legacy"
+  ip_stack = "both"
 ```
 
 ### bootstrap_ip
@@ -200,6 +261,7 @@ If `bootstrap_ip` is empty, `ctrld` will resolve this itself using its own boots
 
  - type: ip address string
  - required: no
+ - Default: ""
 
 ### endpoint
 IP address, hostname or URL of upstream DNS. Used together with `Type` of the endpoint.
@@ -214,6 +276,7 @@ Human-readable name of the upstream.
 
 - Type: string
 - Required: no
+- Default: ""
 
 ### timeout
 Timeout in milliseconds before request failsover to the next upstream (if defined). 
@@ -221,15 +284,34 @@ Timeout in milliseconds before request failsover to the next upstream (if define
 Value `0` means no timeout.
 
  - Type: number
- - required: no
+ - Required: no
+ - Default: 0
 
 ### type
 The protocol that `ctrld` will use to send DNS requests to upstream.
 
  - Type: string
- - required: yes
+ - Required: yes
  - Valid values: `doh`, `doh3`, `dot`, `doq`, `legacy`, `os`
 
+### ip_stack
+Specifying what kind of ip stack that `ctrld` will use to connect to upstream.
+
+ - Type: string
+ - Required: no
+ - Valid values:
+   - `both`: using either ipv4 or ipv6.
+   - `v4`:   only dial upstream via IPv4, never dial IPv6.
+   - `v6`:   only dial upstream via IPv6, never dial IPv4.
+   - `split`:
+     - If `A` record is requested -> dial via ipv4.
+     - If `AAAA` or any other record is requested -> dial ipv6 (if available, otherwise ipv4)
+
+If `ip_stack` is empty, or undefined:
+
+ - Default value is `both` for non-Control D resolvers.
+ - Default value is `split` for Control D resolvers.
+
 ## Network
 The `[network]` section defines networks from which DNS queries can originate from. These are used in policies. You can define multiple networks, and each one can have multiple cidrs.
 
@@ -248,12 +330,14 @@ Name of the network.
 
  - Type: string
  - Required: no
+ - Default: ""
 
 ### cidrs
 Specifies the network addresses that the `listener` will accept requests from. You will see more details in the listener policy section.
 
  - Type: array of network CIDR string
  - Required: no
+ - Default: []
 
 
 ## listener
@@ -271,22 +355,25 @@ The `[listener]` section specifies the ip and port of the local DNS server. You
 ```
 
 ### ip
-IP address that serves the incoming requests.
+IP address that serves the incoming requests. If `ip` is empty, ctrld will listen on all available addresses.
 
-- Type: string
+- Type: ip address string
-- Required: yes
+- Required: no
+- Default: "0.0.0.0" or RFC1918 addess or "127.0.0.1" (depending on platform)
 
 ### port
-Port number that the listener will listen on for incoming requests.
+Port number that the listener will listen on for incoming requests. If `port` is `0`, a random available port will be chosen.
 
 - Type: number
-- Required: yes
+- Required: no
+- Default: 0 or 53 or 5354 (depending on platform)
 
 ### restricted
 If set to `true` makes the listener `REFUSE` DNS queries from all source IP addresses that are not explicitly defined in the policy using a `network`. 
 
 - Type: bool
 - Required: no
+- Default: false
 
 ### policy
 Allows `ctrld` to set policy rules to determine which upstreams the requests will be forwarded to.
@@ -330,19 +417,30 @@ rules = [
 
 - Type: string
 - Required: no
+- Default: ""
 
 ### networks:
 `networks` is the list of network rules of the policy.
 
-- type: array of networks
+- Type: array of networks
+- Required: no
+- Default: []
 
 ### rules:
 `rules` is the list of domain rules within the policy. Domain can be either FQDN or wildcard domain.
 
-- type: array of rule
+- Type: array of rule
+- Required: no
+- Default: []
 
 ### failover_rcodes
-For non success response, `failover_rcodes` allows the request to be forwarded to next upstream, if the response `RCODE` matches any value defined in `failover_rcodes`. For example:
+For non success response, `failover_rcodes` allows the request to be forwarded to next upstream, if the response `RCODE` matches any value defined in `failover_rcodes`.
+
+- Type: array of string
+- Required: no
+- Default: []
+- 
+For example:
 
 ```toml
 [listener.0.policy]

doh.go

@@ -7,25 +7,35 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 
 	"github.com/miekg/dns"
 )
 
+const (
+	dohMacHeader         = "x-cd-mac"
+	dohIPHeader          = "x-cd-ip"
+	dohHostHeader        = "x-cd-host"
+	headerApplicationDNS = "application/dns-message"
+)
+
 func newDohResolver(uc *UpstreamConfig) *dohResolver {
 	r := &dohResolver{
-		endpoint:          uc.Endpoint,
+		endpoint:          uc.u,
 		isDoH3:            uc.Type == ResolverTypeDOH3,
-		transport:         uc.transport,
 		http3RoundTripper: uc.http3RoundTripper,
+		sendClientInfo:    uc.UpstreamSendClientInfo(),
+		uc:                uc,
 	}
 	return r
 }
 
 type dohResolver struct {
-	endpoint          string
+	uc                *UpstreamConfig
+	endpoint          *url.URL
 	isDoH3            bool
-	transport         *http.Transport
 	http3RoundTripper http.RoundTripper
+	sendClientInfo    bool
 }
 
 func (r *dohResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
@@ -33,26 +43,34 @@ func (r *dohResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, erro
 	if err != nil {
 		return nil, err
 	}
+
 	enc := base64.RawURLEncoding.EncodeToString(data)
-	url := fmt.Sprintf("%s?dns=%s", r.endpoint, enc)
+	query := r.endpoint.Query()
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	query.Add("dns", enc)
+
+	endpoint := *r.endpoint
+	endpoint.RawQuery = query.Encode()
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint.String(), nil)
 	if err != nil {
 		return nil, fmt.Errorf("could not create request: %w", err)
 	}
-	req.Header.Set("Content-Type", "application/dns-message")
+	addHeader(ctx, req, r.sendClientInfo)
-	req.Header.Set("Accept", "application/dns-message")
+	dnsTyp := uint16(0)
-
+	if len(msg.Question) > 0 {
-	c := http.Client{Transport: r.transport}
+		dnsTyp = msg.Question[0].Qtype
+	}
+	c := http.Client{Transport: r.uc.dohTransport(dnsTyp)}
 	if r.isDoH3 {
-		if r.http3RoundTripper == nil {
+		transport := r.uc.doh3Transport(dnsTyp)
+		if transport == nil {
 			return nil, errors.New("DoH3 is not supported")
 		}
-		c.Transport = r.http3RoundTripper
+		c.Transport = transport
 	}
 	resp, err := c.Do(req)
 	if err != nil {
 		if r.isDoH3 {
-			if closer, ok := r.http3RoundTripper.(io.Closer); ok {
+			if closer, ok := c.Transport.(io.Closer); ok {
 				closer.Close()
 			}
 		}
@@ -70,5 +88,27 @@ func (r *dohResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, erro
 	}
 
 	answer := new(dns.Msg)
-	return answer, answer.Unpack(buf)
+	if err := answer.Unpack(buf); err != nil {
+		return nil, fmt.Errorf("answer.Unpack: %w", err)
+	}
+	return answer, nil
+}
+
+func addHeader(ctx context.Context, req *http.Request, sendClientInfo bool) {
+	req.Header.Set("Content-Type", headerApplicationDNS)
+	req.Header.Set("Accept", headerApplicationDNS)
+	if sendClientInfo {
+		if ci, ok := ctx.Value(ClientInfoCtxKey{}).(*ClientInfo); ok && ci != nil {
+			if ci.Mac != "" {
+				req.Header.Set(dohMacHeader, ci.Mac)
+			}
+			if ci.IP != "" {
+				req.Header.Set(dohIPHeader, ci.IP)
+			}
+			if ci.Hostname != "" {
+				req.Header.Set(dohHostHeader, ci.Hostname)
+			}
+		}
+	}
+	Log(ctx, ProxyLogger.Load().Debug().Interface("header", req.Header), "sending request header")
 }

doq.go

@@ -20,11 +20,17 @@ type doqResolver struct {
 func (r *doqResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
 	endpoint := r.uc.Endpoint
 	tlsConfig := &tls.Config{NextProtos: []string{"doq"}}
-	if r.uc.BootstrapIP != "" {
+	ip := r.uc.BootstrapIP
-		tlsConfig.ServerName = r.uc.Domain
+	if ip == "" {
-		_, port, _ := net.SplitHostPort(endpoint)
+		dnsTyp := uint16(0)
-		endpoint = net.JoinHostPort(r.uc.BootstrapIP, port)
+		if msg != nil && len(msg.Question) > 0 {
+			dnsTyp = msg.Question[0].Qtype
+		}
+		ip = r.uc.bootstrapIPForDNSType(dnsTyp)
 	}
+	tlsConfig.ServerName = r.uc.Domain
+	_, port, _ := net.SplitHostPort(endpoint)
+	endpoint = net.JoinHostPort(ip, port)
 	return resolve(ctx, msg, endpoint, tlsConfig)
 }
 

dot.go

@@ -14,18 +14,26 @@ type dotResolver struct {
 
 func (r *dotResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
 	// The dialer is used to prevent bootstrapping cycle.
-	// If r.endpoing is set to dns.controld.dev, we need to resolve
+	// If r.endpoint is set to dns.controld.dev, we need to resolve
 	// dns.controld.dev first. By using a dialer with custom resolver,
 	// we ensure that we can always resolve the bootstrap domain
 	// regardless of the machine DNS status.
 	dialer := newDialer(net.JoinHostPort(bootstrapDNS, "53"))
+	dnsTyp := uint16(0)
+	if msg != nil && len(msg.Question) > 0 {
+		dnsTyp = msg.Question[0].Qtype
+	}
+
+	tcpNet, _ := r.uc.netForDNSType(dnsTyp)
 	dnsClient := &dns.Client{
-		Net:    "tcp-tls",
+		Net:       tcpNet,
-		Dialer: dialer,
+		Dialer:    dialer,
+		TLSConfig: &tls.Config{RootCAs: r.uc.certPool},
 	}
 	endpoint := r.uc.Endpoint
 	if r.uc.BootstrapIP != "" {
-		dnsClient.TLSConfig = &tls.Config{ServerName: r.uc.Domain}
+		dnsClient.TLSConfig.ServerName = r.uc.Domain
+		dnsClient.Net = "tcp-tls"
 		_, port, _ := net.SplitHostPort(endpoint)
 		endpoint = net.JoinHostPort(r.uc.BootstrapIP, port)
 	}

errors.go

@@ -1,43 +0,0 @@
-package ctrld
-
-// TODO(cuonglm): use stdlib once we bump minimum version to 1.20
-
-func joinErrors(errs ...error) error {
-	n := 0
-	for _, err := range errs {
-		if err != nil {
-			n++
-		}
-	}
-	if n == 0 {
-		return nil
-	}
-	e := &joinError{
-		errs: make([]error, 0, n),
-	}
-	for _, err := range errs {
-		if err != nil {
-			e.errs = append(e.errs, err)
-		}
-	}
-	return e
-}
-
-type joinError struct {
-	errs []error
-}
-
-func (e *joinError) Error() string {
-	var b []byte
-	for i, err := range e.errs {
-		if i > 0 {
-			b = append(b, '\n')
-		}
-		b = append(b, err.Error()...)
-	}
-	return string(b)
-}
-
-func (e *joinError) Unwrap() []error {
-	return e.errs
-}

go.mod

@@ -1,28 +1,35 @@
 module github.com/Control-D-Inc/ctrld
 
-go 1.19
+go 1.20
 
 require (
-	github.com/coreos/go-systemd/v22 v22.3.3-0.20220203105225-a9a7ef127534
+	github.com/coreos/go-systemd/v22 v22.5.0
-	github.com/frankban/quicktest v1.14.3
+	github.com/cuonglm/osinfo v0.0.0-20230329055532-c513f836da19
+	github.com/frankban/quicktest v1.14.5
 	github.com/fsnotify/fsnotify v1.6.0
 	github.com/go-playground/validator/v10 v10.11.1
-	github.com/godbus/dbus/v5 v5.0.6
+	github.com/godbus/dbus/v5 v5.1.0
 	github.com/hashicorp/golang-lru/v2 v2.0.1
 	github.com/illarion/gonotify v1.0.1
-	github.com/insomniacslk/dhcp v0.0.0-20211209223715-7d93572ebe8e
+	github.com/insomniacslk/dhcp v0.0.0-20230407062729-974c6f05fe16
+	github.com/josharian/native v1.1.1-0.20230202152459-5c7d0dd6ab86
 	github.com/kardianos/service v1.2.1
-	github.com/miekg/dns v1.1.50
+	github.com/miekg/dns v1.1.55
-	github.com/pelletier/go-toml/v2 v2.0.6
+	github.com/olekukonko/tablewriter v0.0.5
+	github.com/pelletier/go-toml/v2 v2.0.8
 	github.com/quic-go/quic-go v0.32.0
 	github.com/rs/zerolog v1.28.0
-	github.com/spf13/cobra v1.4.0
+	github.com/spf13/cobra v1.7.0
-	github.com/spf13/viper v1.14.0
+	github.com/spf13/pflag v1.0.5
-	github.com/stretchr/testify v1.8.1
+	github.com/spf13/viper v1.16.0
-	golang.org/x/sync v0.1.0
+	github.com/stretchr/testify v1.8.3
-	golang.org/x/sys v0.5.0
+	github.com/vishvananda/netlink v1.2.1-beta.2
+	go4.org/mem v0.0.0-20220726221520-4f986261bf13
+	golang.org/x/net v0.10.0
+	golang.org/x/sync v0.2.0
+	golang.org/x/sys v0.8.1-0.20230609144347-5059a07aa46a
 	golang.zx2c4.com/wireguard/windows v0.5.3
-	tailscale.com v1.34.1
+	tailscale.com v1.44.0
 )
 
 require (
@@ -35,42 +42,44 @@ require (
 	github.com/google/go-cmp v0.5.9 // indirect
 	github.com/google/pprof v0.0.0-20210407192527-94a9f03dee38 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
-	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/josharian/native v1.0.0 // indirect
+	github.com/jsimonetti/rtnetlink v1.3.2 // indirect
-	github.com/jsimonetti/rtnetlink v1.1.2-0.20220408201609-d380b505068b // indirect
+	github.com/kr/pretty v0.3.1 // indirect
-	github.com/kr/pretty v0.3.0 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/leodido/go-urn v1.2.1 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
-	github.com/mattn/go-colorable v0.1.12 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
-	github.com/mattn/go-isatty v0.0.14 // indirect
+	github.com/mattn/go-isatty v0.0.18 // indirect
+	github.com/mattn/go-runewidth v0.0.14 // indirect
 	github.com/mdlayher/ethernet v0.0.0-20190606142754-0394541c37b7 // indirect
-	github.com/mdlayher/netlink v1.6.0 // indirect
+	github.com/mdlayher/netlink v1.7.2 // indirect
 	github.com/mdlayher/raw v0.0.0-20191009151244-50f2db8cc065 // indirect
-	github.com/mdlayher/socket v0.2.3 // indirect
+	github.com/mdlayher/socket v0.4.1 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/onsi/ginkgo/v2 v2.2.0 // indirect
-	github.com/pelletier/go-toml v1.9.5 // indirect
+	github.com/pierrec/lz4/v4 v4.1.17 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/quic-go/qpack v0.4.0 // indirect
 	github.com/quic-go/qtls-go1-18 v0.2.0 // indirect
 	github.com/quic-go/qtls-go1-19 v0.2.0 // indirect
 	github.com/quic-go/qtls-go1-20 v0.1.0 // indirect
-	github.com/rogpeppe/go-internal v1.8.1-0.20211023094830-115ce09fd6b4 // indirect
+	github.com/rivo/uniseg v0.4.4 // indirect
-	github.com/spf13/afero v1.9.3 // indirect
+	github.com/rogpeppe/go-internal v1.10.0 // indirect
-	github.com/spf13/cast v1.5.0 // indirect
+	github.com/spf13/afero v1.9.5 // indirect
+	github.com/spf13/cast v1.5.1 // indirect
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/subosito/gotenv v1.4.2 // indirect
-	github.com/subosito/gotenv v1.4.1 // indirect
+	github.com/u-root/uio v0.0.0-20230305220412-3e8cd9d6bf63 // indirect
-	github.com/u-root/uio v0.0.0-20220204230159-dac05f7d2cb4 // indirect
+	github.com/vishvananda/netns v0.0.4 // indirect
-	go4.org/mem v0.0.0-20210711025021-927187094b94 // indirect
+	golang.org/x/crypto v0.9.0 // indirect
-	golang.org/x/crypto v0.4.0 // indirect
+	golang.org/x/exp v0.0.0-20230425010034-47ecfdc1ba53 // indirect
-	golang.org/x/exp v0.0.0-20221205204356-47842c84f3db // indirect
+	golang.org/x/mod v0.10.0 // indirect
-	golang.org/x/mod v0.6.0 // indirect
+	golang.org/x/text v0.9.0 // indirect
-	golang.org/x/net v0.7.0 // indirect
+	golang.org/x/tools v0.9.1 // indirect
-	golang.org/x/text v0.7.0 // indirect
-	golang.org/x/tools v0.2.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
-	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
+
+replace github.com/mr-karan/doggo => github.com/Windscribe/doggo v0.0.0-20220919152748-2c118fc391f8
+
+replace github.com/rs/zerolog => github.com/Windscribe/zerolog v0.0.0-20230503170159-e6aa153233be

go.sum

@@ -38,22 +38,25 @@ cloud.google.com/go/storage v1.14.0/go.mod h1:GrKmX003DSIwi9o29oFT7YDnHYwZoctc3f
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/Windscribe/zerolog v0.0.0-20230503170159-e6aa153233be h1:qBKVRi7Mom5heOkyZ+NCIu9HZBiNCsRqrRe5t9pooik=
+github.com/Windscribe/zerolog v0.0.0-20230503170159-e6aa153233be/go.mod h1:/tk+P47gFdPXq4QYjvCmT5/Gsug2nagsFWBWhAiSi1w=
 github.com/alexbrainman/sspi v0.0.0-20210105120005-909beea2cc74 h1:Kk6a4nehpJ3UuJRqlA3JxYxBZEqCeOmATOvrbT4p9RA=
 github.com/alexbrainman/sspi v0.0.0-20210105120005-909beea2cc74/go.mod h1:cEWa1LVoE5KvSD9ONXsZrj0z6KqySlCCNKHlLzbqAt4=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
 github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
-github.com/cilium/ebpf v0.8.1 h1:bLSSEbBLqGPXxls55pGr5qWZaTqcmfDJHhou7t254ao=
+github.com/cilium/ebpf v0.10.0 h1:nk5HPMeoBXtOzbkZBWym+ZWq1GIiHUsBFXxwewXAHLQ=
-github.com/cilium/ebpf v0.8.1/go.mod h1:f5zLIM0FSNuAkSyLAN7X+Hy6yznlF1mNiWUMfxMtrgk=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cncf/udpa/go v0.0.0-20191209042840-269d4d468f6f/go.mod h1:M8M6+tZqaGXZJjfX53e64911xZQV5JYwmTeXPW+k8Sc=
 github.com/cncf/udpa/go v0.0.0-20200629203442-efcf912fb354/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=
 github.com/cncf/udpa/go v0.0.0-20201120205902-5459f2c99403/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=
-github.com/coreos/go-systemd/v22 v22.3.3-0.20220203105225-a9a7ef127534 h1:rtAn27wIbmOGUs7RIbVgPEjb31ehTVniDwPGXyMxm5U=
+github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=
-github.com/coreos/go-systemd/v22 v22.3.3-0.20220203105225-a9a7ef127534/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
-github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/cuonglm/osinfo v0.0.0-20230329055532-c513f836da19 h1:7P/f19Mr0oa3ug8BYt4JuRe/Zq3dF4Mrr4m8+Kw+Hcs=
+github.com/cuonglm/osinfo v0.0.0-20230329055532-c513f836da19/go.mod h1:G45410zMgmnSjLVKCq4f6GpbYAzoP2plX9rPwgx6C24=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -63,10 +66,8 @@ github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1m
 github.com/envoyproxy/go-control-plane v0.9.7/go.mod h1:cwu0lG7PUMfa9snN8LXBig5ynNVH9qI8YYLbd1fK2po=
 github.com/envoyproxy/go-control-plane v0.9.9-0.20201210154907-fd9021fe5dad/go.mod h1:cXg6YxExXjJnVBQHBLXeUAgxn2UodCpnH306RInaBQk=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
-github.com/fanliao/go-promise v0.0.0-20141029170127-1890db352a72/go.mod h1:PjfxuH4FZdUyfMdtBio2lsRr1AKEaVPwelzuHuh8Lqc=
+github.com/frankban/quicktest v1.14.5 h1:dfYrrRyLtiqT9GyKXgdh+k4inNeTvmGbuSgZ3lx3GhA=
-github.com/frankban/quicktest v1.14.0/go.mod h1:NeW+ay9A/U67EYXNFA1nPE8e/tnQv/09mUdL/ijj8og=
+github.com/frankban/quicktest v1.14.5/go.mod h1:4ptaffx2x8+WTWXmUCuVU6aPUX1/Mz7zb5vbUoiM6w0=
-github.com/frankban/quicktest v1.14.3 h1:FJKSZTDHjyhriyC81FLQ0LY93eSai0ZyR/ZIkd3ZUKE=
-github.com/frankban/quicktest v1.14.3/go.mod h1:mgiwOwqx65TmIk1wJ6Q7wvnVMocbUorkibMOrVTHZps=
 github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
 github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
 github.com/go-gl/glfw v0.0.0-20190409004039-e6da0acd62b1/go.mod h1:vR7hzQXu2zJy9AVAgeJqvqgH9Q5CA+iKCZ2gyEVpxRU=
@@ -83,8 +84,8 @@ github.com/go-playground/validator/v10 v10.11.1/go.mod h1:i+3WkQ1FvaUjjxh1kSvIA4
 github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0 h1:p104kn46Q8WdvHunIJ9dAyjPVtrBPhSr3KT2yUst43I=
 github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0/go.mod h1:fyg7847qk6SyHyPtNmDHnmrv/HOrqktSC+C9fM+CJOE=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
-github.com/godbus/dbus/v5 v5.0.6 h1:mkgN1ofwASrYnJ5W6U/BxG15eXXXjirgZc7CLqkcaro=
+github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
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@@ -124,8 +125,6 @@ github.com/google/go-cmp v0.5.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
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@@ -148,7 +147,6 @@ github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+
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@@ -156,34 +154,30 @@ github.com/hashicorp/golang-lru/v2 v2.0.1/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyf
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@@ -192,35 +186,39 @@ github.com/leodido/go-urn v1.2.1 h1:BqpAaACuzVSgi/VLzGZIobT2z4v53pjosyNd9Yv6n/w=
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 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
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@@ -237,29 +235,29 @@ github.com/quic-go/qtls-go1-20 v0.1.0 h1:d1PK3ErFy9t7zxKsG3NXBJXZjp/kMLoIb3y/kV5
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@@ -271,13 +269,17 @@ github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
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@@ -289,18 +291,18 @@ go.opencensus.io v0.22.2/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.22.3/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.22.4/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.22.5/go.mod h1:5pWMHQbX5EPX2/62yrJeAkowc+lfs/XD7Uxpq3pI6kk=
-go4.org/mem v0.0.0-20210711025021-927187094b94 h1:OAAkygi2Js191AJP1Ds42MhJRgeofeKGjuoUqNp1QC4=
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@@ -311,8 +313,8 @@ golang.org/x/exp v0.0.0-20191227195350-da58074b4299/go.mod h1:2RIsYlXP63K8oxa1u0
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@@ -337,8 +339,8 @@ golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
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-golang.org/x/mod v0.6.0 h1:b9gGHsz9/HhJ3HF5DHQytPpuwocVTChQJK3AvoLRD5I=
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@@ -352,8 +354,6 @@ golang.org/x/net v0.0.0-20190603091049-60506f45cf65/go.mod h1:HSz+uSET+XFnRR8LxR
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 golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
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 golang.org/x/net v0.0.0-20200202094626-16171245cfb2/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -368,20 +368,15 @@ golang.org/x/net v0.0.0-20200520182314-0ba52f642ac2/go.mod h1:qpuaurCH72eLCgpAm/
 golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20200707034311-ab3426394381/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
-golang.org/x/net v0.0.0-20201010224723-4f7140c49acb/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20201031054903-ff519b6c9102/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
-golang.org/x/net v0.0.0-20201110031124-69a78807bb2b/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20201209123823-ac852fbbde11/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20201224014010-6772e930b67b/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
-golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20210928044308-7d9f5e0b762b/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
+golang.org/x/net v0.10.0 h1:X2//UzNDwYmtCLn7To6G58Wr6f5ahEAQgKNzv9Y951M=
-golang.org/x/net v0.7.0 h1:rJrUqqhjsgNp7KqAIc25s9pZnjU7TUcSY7HcVZjdn1g=
+golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
-golang.org/x/net v0.7.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -402,12 +397,11 @@ golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.2.0 h1:PUR+T4wwASmuSTYdKjYHI5TD22Wy5ogLU5qZCOLxBrI=
-golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.2.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190411185658-b44545bcd369/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190418153312-f0ce4c0180be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190502145724-3ef323f4f1fd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -416,15 +410,14 @@ golang.org/x/sys v0.0.0-20190606122018-79a91cf218c4/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190606165138-5da285871e9c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190624142023-c5567b49c5d0/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190826190057-c7b8b68b1456/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191001151750-bb3f8db39f24/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191228213918-04cbcbbfeed8/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200113162924-86b910548bc1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200122134326-e047566fdf82/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200212091648-12a6c2dcc1e4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200217220822-9197077df867/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200302150141-5c8b2ff67527/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -433,12 +426,11 @@ golang.org/x/sys v0.0.0-20200501052902-10377860bb8e/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200511232937-7e40ca221e25/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200515095857-1151b9dac4a9/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200523222454-059865788121/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200728102440-3e129f6d46b1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200803210538-64077c9b5642/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200905004654-be1d3432aa8f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20201009025420-dfb3f7c4e634/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201015000850-e3ed0017c211/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20201101102859-da207088b7d1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201201145000-ef89a241ccb3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210104204734-6f8348627aad/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -448,19 +440,18 @@ golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423185535-09eb48e85fd7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
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 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210806184541-e5e7981a1069/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
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 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
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 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -469,8 +460,8 @@ golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.4/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
-golang.org/x/text v0.7.0 h1:4BRB4x83lYWy72KwLD/qYDuTu7q9PjSagHvijDw7cLo=
+golang.org/x/text v0.9.0 h1:2sjJmO8cDvYveuX97RDLsxlyUxLl+GHoLxBiRdHllBE=
-golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
+golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -480,7 +471,6 @@ golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190312151545-0bb0c0a6e846/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190312170243-e65039ee4138/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
-golang.org/x/tools v0.0.0-20190328211700-ab21143f2384/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190425150028-36563e24a262/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 golang.org/x/tools v0.0.0-20190506145303-2d16b83fe98c/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
@@ -523,9 +513,8 @@ golang.org/x/tools v0.0.0-20210105154028-b0ab187a4818/go.mod h1:emZCQorbCU4vsT4f
 golang.org/x/tools v0.0.0-20210108195828-e2f9c7f1fc8e/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
 golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
 golang.org/x/tools v0.1.1/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
-golang.org/x/tools v0.1.6-0.20210726203631-07bc1bf47fb2/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/tools v0.9.1 h1:8WMNJAz3zrtPmnYC7ISf5dEn3MT0gY7jBJfw27yrrLo=
-golang.org/x/tools v0.2.0 h1:G6AHpWxTMGY1KyEYoAQ5WTtIekUUvDNjan3ugu60JvE=
+golang.org/x/tools v0.9.1/go.mod h1:owI94Op576fPu3cIGQeHs3joujW/2Oc6MtlxbF5dfNc=
-golang.org/x/tools v0.2.0/go.mod h1:y4OqIKeOV/fWJetJ8bXPU1sEVniLMIyDAZWeHdV+NTA=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
@@ -620,7 +609,7 @@ google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2
 google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 google.golang.org/protobuf v1.24.0/go.mod h1:r/3tXBNzIEhYS9I1OUVjXDlt8tc493IdKGjtUeSXeh4=
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
-google.golang.org/protobuf v1.28.1 h1:d0NfwRgPtno5B1Wa6L2DAG+KivqkdutMf1UhdNx175w=
+google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
@@ -629,8 +618,6 @@ gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/ini.v1 v1.67.0 h1:Dgnx+6+nfE+IfzjUEISNeydPJh9AXNNsWbGP9KzCsOA=
 gopkg.in/ini.v1 v1.67.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
-gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
@@ -645,5 +632,5 @@ honnef.co/go/tools v0.0.1-2020.1.4/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9
 rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=
 rsc.io/quote/v3 v3.1.0/go.mod h1:yEA65RcK8LyAZtP9Kv3t0HmxON59tX3rD+tICJqUlj0=
 rsc.io/sampler v1.3.0/go.mod h1:T1hPZKmBbMNahiBKFy5HrXp6adAjACjK9JXDnKaTXpA=
-tailscale.com v1.34.1 h1:tqm9Ww4ltyYp3IPe7vCGch6tT6j5G/WXPQ6BrVZ6pdI=
+tailscale.com v1.44.0 h1:MPos9n30kJvdyfL52045gVFyNg93K+bwgDsr8gqKq2o=
-tailscale.com v1.34.1/go.mod h1:ZsBP7rjzzB2rp+UCOumr9DAe0EQ6OPivwSXcz/BrekQ=
+tailscale.com v1.44.0/go.mod h1:+iYwTdeHyVJuNDu42Zafwihq1Uqfh+pW7pRaY1GD328=

internal/certs/root_ca.go

@@ -0,0 +1,22 @@
+package certs
+
+import (
+	"crypto/x509"
+	_ "embed"
+	"sync"
+)
+
+var (
+	//go:embed cacert.pem
+	caRoots        []byte
+	caCertPoolOnce sync.Once
+	caCertPool     *x509.CertPool
+)
+
+func CACertPool() *x509.CertPool {
+	caCertPoolOnce.Do(func() {
+		caCertPool = x509.NewCertPool()
+		caCertPool.AppendCertsFromPEM(caRoots)
+	})
+	return caCertPool
+}

internal/certs/root_ca_test.go

@@ -0,0 +1,27 @@
+package certs
+
+import (
+	"crypto/tls"
+	"net/http"
+	"testing"
+	"time"
+)
+
+func TestCACertPool(t *testing.T) {
+	c := &http.Client{
+		Transport: &http.Transport{
+			TLSClientConfig: &tls.Config{
+				RootCAs: CACertPool(),
+			},
+		},
+		Timeout: 2 * time.Second,
+	}
+	resp, err := c.Get("https://freedns.controld.com/p1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if !resp.TLS.HandshakeComplete {
+		t.Error("TLS handshake is not complete")
+	}
+}

internal/clientinfo/arp.go

@@ -0,0 +1,46 @@
+package clientinfo
+
+import "sync"
+
+type arpDiscover struct {
+	mac sync.Map // ip  => mac
+	ip  sync.Map // mac => ip
+}
+
+func (a *arpDiscover) refresh() error {
+	a.scan()
+	return nil
+}
+
+func (a *arpDiscover) LookupIP(mac string) string {
+	val, ok := a.ip.Load(mac)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+func (a *arpDiscover) LookupMac(ip string) string {
+	val, ok := a.mac.Load(ip)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+func (a *arpDiscover) String() string {
+	return "arp"
+}
+
+func (a *arpDiscover) List() []string {
+	var ips []string
+	a.ip.Range(func(key, value any) bool {
+		ips = append(ips, value.(string))
+		return true
+	})
+	a.mac.Range(func(key, value any) bool {
+		ips = append(ips, key.(string))
+		return true
+	})
+	return ips
+}

internal/clientinfo/arp_linux.go

@@ -0,0 +1,28 @@
+package clientinfo
+
+import (
+	"bufio"
+	"os"
+	"strings"
+)
+
+const procNetArpFile = "/proc/net/arp"
+
+func (a *arpDiscover) scan() {
+	f, err := os.Open(procNetArpFile)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+	s.Scan() // skip header
+	for s.Scan() {
+		line := s.Text()
+		fields := strings.Fields(line)
+		ip := fields[0]
+		mac := fields[3]
+		a.mac.Store(ip, mac)
+		a.ip.Store(mac, ip)
+	}
+}

internal/clientinfo/arp_test.go

@@ -0,0 +1,23 @@
+package clientinfo
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestArpScan(t *testing.T) {
+	a := &arpDiscover{}
+	a.scan()
+
+	for _, table := range []*sync.Map{&a.mac, &a.ip} {
+		count := 0
+		table.Range(func(key, value any) bool {
+			count++
+			t.Logf("%s => %s", key, value)
+			return true
+		})
+		if count == 0 {
+			t.Error("empty result from arp scan")
+		}
+	}
+}

internal/clientinfo/arp_unix.go

@@ -0,0 +1,30 @@
+//go:build !linux && !windows
+
+package clientinfo
+
+import (
+	"os/exec"
+	"strings"
+)
+
+func (a *arpDiscover) scan() {
+	data, err := exec.Command("arp", "-an").Output()
+	if err != nil {
+		return
+	}
+
+	for _, line := range strings.Split(string(data), "\n") {
+		fields := strings.Fields(line)
+		if len(fields) <= 3 {
+			continue
+		}
+
+		// trim brackets
+		ip := strings.ReplaceAll(fields[1], "(", "")
+		ip = strings.ReplaceAll(ip, ")", "")
+
+		mac := fields[3]
+		a.mac.Store(ip, mac)
+		a.ip.Store(mac, ip)
+	}
+}

internal/clientinfo/arp_windows.go

@@ -0,0 +1,38 @@
+package clientinfo
+
+import (
+	"os/exec"
+	"strings"
+)
+
+func (a *arpDiscover) scan() {
+	data, err := exec.Command("arp", "-a").Output()
+	if err != nil {
+		return
+	}
+
+	header := false
+	for _, line := range strings.Split(string(data), "\n") {
+		if len(line) == 0 {
+			continue // empty lines
+		}
+		if line[0] != ' ' {
+			header = true // "Interface:" lines, next is header line.
+			continue
+		}
+		if header {
+			header = false // header lines
+			continue
+		}
+
+		fields := strings.Fields(line)
+		if len(fields) < 2 {
+			continue
+		}
+
+		ip := fields[0]
+		mac := strings.ReplaceAll(fields[1], "-", ":")
+		a.mac.Store(ip, mac)
+		a.ip.Store(mac, ip)
+	}
+}

internal/clientinfo/client_info.go

@@ -0,0 +1,346 @@
+package clientinfo
+
+import (
+	"fmt"
+	"net/netip"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/controld"
+)
+
+// IpResolver is the interface for retrieving IP from Mac.
+type IpResolver interface {
+	fmt.Stringer
+	// LookupIP returns ip of the device with given mac.
+	LookupIP(mac string) string
+}
+
+// MacResolver is the interface for retrieving Mac from IP.
+type MacResolver interface {
+	fmt.Stringer
+	// LookupMac returns mac of the device with given ip.
+	LookupMac(ip string) string
+}
+
+// HostnameByIpResolver is the interface for retrieving hostname from IP.
+type HostnameByIpResolver interface {
+	// LookupHostnameByIP returns hostname of the given ip.
+	LookupHostnameByIP(ip string) string
+}
+
+// HostnameByMacResolver is the interface for retrieving hostname from Mac.
+type HostnameByMacResolver interface {
+	// LookupHostnameByMac returns hostname of the device with given mac.
+	LookupHostnameByMac(mac string) string
+}
+
+// HostnameResolver is the interface for retrieving hostname from either IP or Mac.
+type HostnameResolver interface {
+	fmt.Stringer
+	HostnameByIpResolver
+	HostnameByMacResolver
+}
+
+type refresher interface {
+	refresh() error
+}
+
+type ipLister interface {
+	fmt.Stringer
+	// List returns list of ip known by the resolver.
+	List() []string
+}
+
+type Client struct {
+	IP       netip.Addr
+	Mac      string
+	Hostname string
+	Source   map[string]struct{}
+}
+
+type Table struct {
+	ipResolvers       []IpResolver
+	macResolvers      []MacResolver
+	hostnameResolvers []HostnameResolver
+	refreshers        []refresher
+	initOnce          sync.Once
+
+	dhcp   *dhcp
+	merlin *merlinDiscover
+	arp    *arpDiscover
+	ptr    *ptrDiscover
+	mdns   *mdns
+	cfg    *ctrld.Config
+	quitCh chan struct{}
+	selfIP string
+	cdUID  string
+}
+
+func NewTable(cfg *ctrld.Config, selfIP, cdUID string) *Table {
+	return &Table{
+		cfg:    cfg,
+		quitCh: make(chan struct{}),
+		selfIP: selfIP,
+		cdUID:  cdUID,
+	}
+}
+
+func (t *Table) AddLeaseFile(name string, format ctrld.LeaseFileFormat) {
+	if !t.discoverDHCP() {
+		return
+	}
+	clientInfoFiles[name] = format
+}
+
+func (t *Table) RefreshLoop(stopCh chan struct{}) {
+	timer := time.NewTicker(time.Minute * 5)
+	defer timer.Stop()
+	for {
+		select {
+		case <-timer.C:
+			for _, r := range t.refreshers {
+				_ = r.refresh()
+			}
+		case <-stopCh:
+			close(t.quitCh)
+			return
+		}
+	}
+}
+
+func (t *Table) Init() {
+	t.initOnce.Do(t.init)
+}
+
+func (t *Table) init() {
+	if _, clientID := controld.ParseRawUID(t.cdUID); clientID != "" {
+		ctrld.ProxyLogger.Load().Debug().Msg("start self discovery")
+		t.dhcp = &dhcp{selfIP: t.selfIP}
+		t.dhcp.addSelf()
+		t.ipResolvers = append(t.ipResolvers, t.dhcp)
+		t.macResolvers = append(t.macResolvers, t.dhcp)
+		t.hostnameResolvers = append(t.hostnameResolvers, t.dhcp)
+		return
+	}
+	if t.discoverDHCP() || t.discoverARP() {
+		t.merlin = &merlinDiscover{}
+		if err := t.merlin.refresh(); err != nil {
+			ctrld.ProxyLogger.Load().Error().Err(err).Msg("could not init Merlin discover")
+		} else {
+			t.hostnameResolvers = append(t.hostnameResolvers, t.merlin)
+			t.refreshers = append(t.refreshers, t.merlin)
+		}
+	}
+	if t.discoverDHCP() {
+		t.dhcp = &dhcp{selfIP: t.selfIP}
+		ctrld.ProxyLogger.Load().Debug().Msg("start dhcp discovery")
+		if err := t.dhcp.init(); err != nil {
+			ctrld.ProxyLogger.Load().Error().Err(err).Msg("could not init DHCP discover")
+		} else {
+			t.ipResolvers = append(t.ipResolvers, t.dhcp)
+			t.macResolvers = append(t.macResolvers, t.dhcp)
+			t.hostnameResolvers = append(t.hostnameResolvers, t.dhcp)
+		}
+		go t.dhcp.watchChanges()
+	}
+	if t.discoverARP() {
+		t.arp = &arpDiscover{}
+		ctrld.ProxyLogger.Load().Debug().Msg("start arp discovery")
+		if err := t.arp.refresh(); err != nil {
+			ctrld.ProxyLogger.Load().Error().Err(err).Msg("could not init ARP discover")
+		} else {
+			t.ipResolvers = append(t.ipResolvers, t.arp)
+			t.macResolvers = append(t.macResolvers, t.arp)
+			t.refreshers = append(t.refreshers, t.arp)
+		}
+	}
+	if t.discoverPTR() {
+		t.ptr = &ptrDiscover{resolver: ctrld.NewPrivateResolver()}
+		ctrld.ProxyLogger.Load().Debug().Msg("start ptr discovery")
+		if err := t.ptr.refresh(); err != nil {
+			ctrld.ProxyLogger.Load().Error().Err(err).Msg("could not init PTR discover")
+		} else {
+			t.hostnameResolvers = append(t.hostnameResolvers, t.ptr)
+			t.refreshers = append(t.refreshers, t.ptr)
+		}
+	}
+	if t.discoverMDNS() {
+		t.mdns = &mdns{}
+		ctrld.ProxyLogger.Load().Debug().Msg("start mdns discovery")
+		if err := t.mdns.init(t.quitCh); err != nil {
+			ctrld.ProxyLogger.Load().Error().Err(err).Msg("could not init mDNS discover")
+		} else {
+			t.hostnameResolvers = append(t.hostnameResolvers, t.mdns)
+		}
+	}
+}
+
+func (t *Table) LookupIP(mac string) string {
+	t.initOnce.Do(t.init)
+	for _, r := range t.ipResolvers {
+		if ip := r.LookupIP(mac); ip != "" {
+			return ip
+		}
+	}
+	return ""
+}
+
+func (t *Table) LookupMac(ip string) string {
+	t.initOnce.Do(t.init)
+	for _, r := range t.macResolvers {
+		if mac := r.LookupMac(ip); mac != "" {
+			return mac
+		}
+	}
+	return ""
+}
+
+func (t *Table) LookupHostname(ip, mac string) string {
+	t.initOnce.Do(t.init)
+	for _, r := range t.hostnameResolvers {
+		if name := r.LookupHostnameByIP(ip); name != "" {
+			return name
+		}
+		if name := r.LookupHostnameByMac(mac); name != "" {
+			return name
+		}
+	}
+	return ""
+}
+
+type macEntry struct {
+	mac string
+	src string
+}
+
+type hostnameEntry struct {
+	name string
+	src  string
+}
+
+func (t *Table) lookupMacAll(ip string) []*macEntry {
+	var res []*macEntry
+	for _, r := range t.macResolvers {
+		res = append(res, &macEntry{mac: r.LookupMac(ip), src: r.String()})
+	}
+	return res
+}
+
+func (t *Table) lookupHostnameAll(ip, mac string) []*hostnameEntry {
+	var res []*hostnameEntry
+	for _, r := range t.hostnameResolvers {
+		src := r.String()
+		// For ptrDiscover, lookup hostname may block due to server unavailable,
+		// so only lookup from cache to prevent timeout reached.
+		if ptrResolver, ok := r.(*ptrDiscover); ok {
+			if name := ptrResolver.lookupHostnameFromCache(ip); name != "" {
+				res = append(res, &hostnameEntry{name: name, src: src})
+			}
+			continue
+		}
+		if name := r.LookupHostnameByIP(ip); name != "" {
+			res = append(res, &hostnameEntry{name: name, src: src})
+			continue
+		}
+		if name := r.LookupHostnameByMac(mac); name != "" {
+			res = append(res, &hostnameEntry{name: name, src: src})
+			continue
+		}
+	}
+	return res
+}
+
+// ListClients returns list of clients discovered by ctrld.
+func (t *Table) ListClients() []*Client {
+	for _, r := range t.refreshers {
+		_ = r.refresh()
+	}
+	ipMap := make(map[string]*Client)
+	il := []ipLister{t.dhcp, t.arp, t.ptr, t.mdns}
+	for _, ir := range il {
+		for _, ip := range ir.List() {
+			c, ok := ipMap[ip]
+			if !ok {
+				c = &Client{
+					IP:     netip.MustParseAddr(ip),
+					Source: map[string]struct{}{ir.String(): {}},
+				}
+				ipMap[ip] = c
+			} else {
+				c.Source[ir.String()] = struct{}{}
+			}
+		}
+	}
+	for ip := range ipMap {
+		c := ipMap[ip]
+		for _, e := range t.lookupMacAll(ip) {
+			if c.Mac == "" && e.mac != "" {
+				c.Mac = e.mac
+			}
+			if e.mac != "" {
+				c.Source[e.src] = struct{}{}
+			}
+		}
+		for _, e := range t.lookupHostnameAll(ip, c.Mac) {
+			if c.Hostname == "" && e.name != "" {
+				c.Hostname = e.name
+			}
+			if e.name != "" {
+				c.Source[e.src] = struct{}{}
+			}
+		}
+	}
+	clients := make([]*Client, 0, len(ipMap))
+	for _, c := range ipMap {
+		clients = append(clients, c)
+	}
+	return clients
+}
+
+func (t *Table) discoverDHCP() bool {
+	if t.cfg.Service.DiscoverDHCP == nil {
+		return true
+	}
+	return *t.cfg.Service.DiscoverDHCP
+}
+
+func (t *Table) discoverARP() bool {
+	if t.cfg.Service.DiscoverARP == nil {
+		return true
+	}
+	return *t.cfg.Service.DiscoverARP
+}
+
+func (t *Table) discoverMDNS() bool {
+	if t.cfg.Service.DiscoverMDNS == nil {
+		return true
+	}
+	return *t.cfg.Service.DiscoverMDNS
+}
+
+func (t *Table) discoverPTR() bool {
+	if t.cfg.Service.DiscoverPtr == nil {
+		return true
+	}
+	return *t.cfg.Service.DiscoverPtr
+}
+
+// normalizeIP normalizes the ip parsed from dnsmasq/dhcpd lease file.
+func normalizeIP(in string) string {
+	// dnsmasq may put ip with interface index in lease file, strip it here.
+	ip, _, found := strings.Cut(in, "%")
+	if found {
+		return ip
+	}
+	return in
+}
+
+func normalizeHostname(name string) string {
+	if before, _, found := strings.Cut(name, "."); found {
+		return before // remove ".local.", ".lan.", ... suffix
+	}
+	return name
+}

internal/clientinfo/client_info_test.go

@@ -0,0 +1,27 @@
+package clientinfo
+
+import (
+	"testing"
+)
+
+func Test_normalizeIP(t *testing.T) {
+	tests := []struct {
+		name string
+		in   string
+		want string
+	}{
+		{"v4", "127.0.0.1", "127.0.0.1"},
+		{"v4 with index", "127.0.0.1%lo", "127.0.0.1"},
+		{"v6", "fe80::1", "fe80::1"},
+		{"v6 with index", "fe80::1%22002", "fe80::1"},
+	}
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			if got := normalizeIP(tc.in); got != tc.want {
+				t.Errorf("normalizeIP() = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}

internal/clientinfo/dhcp.go

@@ -0,0 +1,301 @@
+package clientinfo
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"net"
+	"net/netip"
+	"os"
+	"strings"
+	"sync"
+
+	"github.com/fsnotify/fsnotify"
+	"tailscale.com/net/interfaces"
+	"tailscale.com/util/lineread"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/router"
+)
+
+type dhcp struct {
+	mac2name sync.Map // mac => name
+	ip2name  sync.Map // ip  => name
+	ip       sync.Map // mac => ip
+	mac      sync.Map // ip  => mac
+
+	watcher *fsnotify.Watcher
+	selfIP  string
+}
+
+func (d *dhcp) init() error {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		return err
+	}
+	d.addSelf()
+	d.watcher = watcher
+	for file, format := range clientInfoFiles {
+		// Ignore errors for default lease files.
+		_ = d.addLeaseFile(file, format)
+	}
+	return nil
+}
+
+func (d *dhcp) watchChanges() {
+	if d.watcher == nil {
+		return
+	}
+	for {
+		select {
+		case event, ok := <-d.watcher.Events:
+			if !ok {
+				return
+			}
+			if event.Has(fsnotify.Write) || event.Has(fsnotify.Rename) || event.Has(fsnotify.Chmod) || event.Has(fsnotify.Remove) {
+				format := clientInfoFiles[event.Name]
+				if err := d.readLeaseFile(event.Name, format); err != nil && !os.IsNotExist(err) {
+					ctrld.ProxyLogger.Load().Err(err).Str("file", event.Name).Msg("leases file changed but failed to update client info")
+				}
+			}
+		case err, ok := <-d.watcher.Errors:
+			if !ok {
+				return
+			}
+			ctrld.ProxyLogger.Load().Err(err).Msg("could not watch client info file")
+		}
+	}
+
+}
+
+func (d *dhcp) LookupIP(mac string) string {
+	val, ok := d.ip.Load(mac)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+func (d *dhcp) LookupMac(ip string) string {
+	val, ok := d.mac.Load(ip)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+func (d *dhcp) LookupHostnameByIP(ip string) string {
+	val, ok := d.ip2name.Load(ip)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+func (d *dhcp) LookupHostnameByMac(mac string) string {
+	val, ok := d.mac2name.Load(mac)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+func (d *dhcp) String() string {
+	return "dhcp"
+}
+
+func (d *dhcp) List() []string {
+	var ips []string
+	d.ip.Range(func(key, value any) bool {
+		ips = append(ips, value.(string))
+		return true
+	})
+	d.mac.Range(func(key, value any) bool {
+		ips = append(ips, key.(string))
+		return true
+	})
+	return ips
+}
+
+// AddLeaseFile adds given lease file for reading/watching clients info.
+func (d *dhcp) addLeaseFile(name string, format ctrld.LeaseFileFormat) error {
+	if d.watcher == nil {
+		return nil
+	}
+	if err := d.readLeaseFile(name, format); err != nil {
+		return fmt.Errorf("could not read lease file: %w", err)
+	}
+	clientInfoFiles[name] = format
+	return d.watcher.Add(name)
+}
+
+// readLeaseFile reads the lease file with given format, saving client information to dhcp table.
+func (d *dhcp) readLeaseFile(name string, format ctrld.LeaseFileFormat) error {
+	switch format {
+	case ctrld.Dnsmasq:
+		return d.dnsmasqReadClientInfoFile(name)
+	case ctrld.IscDhcpd:
+		return d.iscDHCPReadClientInfoFile(name)
+	}
+	return fmt.Errorf("unsupported format: %s, file: %s", format, name)
+}
+
+// dnsmasqReadClientInfoFile populates dhcp table with client info reading from dnsmasq lease file.
+func (d *dhcp) dnsmasqReadClientInfoFile(name string) error {
+	f, err := os.Open(name)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return d.dnsmasqReadClientInfoReader(f)
+
+}
+
+// dnsmasqReadClientInfoReader likes ctrld.Dnsmasq, but reading from an io.Reader instead of file.
+func (d *dhcp) dnsmasqReadClientInfoReader(reader io.Reader) error {
+	return lineread.Reader(reader, func(line []byte) error {
+		fields := bytes.Fields(line)
+		if len(fields) < 4 {
+			return nil
+		}
+
+		mac := string(fields[1])
+		if _, err := net.ParseMAC(mac); err != nil {
+			// The second field is not a dhcp, skip.
+			return nil
+		}
+		ip := normalizeIP(string(fields[2]))
+		if net.ParseIP(ip) == nil {
+			ctrld.ProxyLogger.Load().Warn().Msgf("invalid ip address entry: %q", ip)
+			ip = ""
+		}
+
+		d.mac.Store(ip, mac)
+		d.ip.Store(mac, ip)
+		hostname := string(fields[3])
+		if hostname == "*" {
+			return nil
+		}
+		name := normalizeHostname(hostname)
+		d.mac2name.Store(mac, name)
+		d.ip2name.Store(ip, name)
+		return nil
+	})
+}
+
+// iscDHCPReadClientInfoFile populates dhcp table with client info reading from isc-dhcpd lease file.
+func (d *dhcp) iscDHCPReadClientInfoFile(name string) error {
+	f, err := os.Open(name)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return d.iscDHCPReadClientInfoReader(f)
+}
+
+// iscDHCPReadClientInfoReader likes ctrld.IscDhcpd, but reading from an io.Reader instead of file.
+func (d *dhcp) iscDHCPReadClientInfoReader(reader io.Reader) error {
+	s := bufio.NewScanner(reader)
+	var ip, mac, hostname string
+	for s.Scan() {
+		line := s.Text()
+		if strings.HasPrefix(line, "}") {
+			d.mac.Store(ip, mac)
+			d.ip.Store(mac, ip)
+			if hostname != "" && hostname != "*" {
+				name := normalizeHostname(hostname)
+				d.mac2name.Store(mac, name)
+				d.ip2name.Store(ip, hostname)
+				ip, mac, hostname = "", "", ""
+			}
+			continue
+		}
+		fields := strings.Fields(line)
+		if len(fields) < 2 {
+			continue
+		}
+		switch fields[0] {
+		case "lease":
+			ip = normalizeIP(strings.ToLower(fields[1]))
+			if net.ParseIP(ip) == nil {
+				ctrld.ProxyLogger.Load().Warn().Msgf("invalid ip address entry: %q", ip)
+				ip = ""
+			}
+		case "hardware":
+			if len(fields) >= 3 {
+				mac = strings.ToLower(strings.TrimRight(fields[2], ";"))
+				if _, err := net.ParseMAC(mac); err != nil {
+					// Invalid dhcp, skip.
+					mac = ""
+				}
+			}
+		case "client-hostname":
+			hostname = strings.Trim(fields[1], `";`)
+		}
+	}
+	return nil
+}
+
+// addSelf populates current host info to dhcp, so queries from
+// the host itself can be attached with proper client info.
+func (d *dhcp) addSelf() {
+	hostname, err := os.Hostname()
+	if err != nil {
+		ctrld.ProxyLogger.Load().Err(err).Msg("could not get hostname")
+		return
+	}
+	hostname = normalizeHostname(hostname)
+	d.ip2name.Store("127.0.0.1", hostname)
+	d.ip2name.Store("::1", hostname)
+	found := false
+	interfaces.ForeachInterface(func(i interfaces.Interface, prefixes []netip.Prefix) {
+		mac := i.HardwareAddr.String()
+		// Skip loopback interfaces, info was stored above.
+		if mac == "" {
+			return
+		}
+		addrs, _ := i.Addrs()
+		for _, addr := range addrs {
+			if found {
+				return
+			}
+			ipNet, ok := addr.(*net.IPNet)
+			if !ok {
+				continue
+			}
+			ip := ipNet.IP
+			d.mac.Store(ip.String(), mac)
+			d.ip.Store(mac, ip.String())
+			if ip.To4() != nil {
+				d.mac.Store("127.0.0.1", mac)
+			} else {
+				d.mac.Store("::1", mac)
+			}
+			d.mac2name.Store(mac, hostname)
+			d.ip2name.Store(ip.String(), hostname)
+			// If we have self IP set, and this IP is it, use this IP only.
+			if ip.String() == d.selfIP {
+				found = true
+			}
+		}
+	})
+	for _, netIface := range router.SelfInterfaces() {
+		mac := netIface.HardwareAddr.String()
+		if mac == "" {
+			return
+		}
+		d.mac2name.Store(mac, hostname)
+		addrs, _ := netIface.Addrs()
+		for _, addr := range addrs {
+			ipNet, ok := addr.(*net.IPNet)
+			if !ok {
+				continue
+			}
+			ip := ipNet.IP
+			d.mac.LoadOrStore(ip.String(), mac)
+			d.ip.LoadOrStore(mac, ip.String())
+			d.ip2name.Store(ip.String(), hostname)
+		}
+	}
+}

internal/clientinfo/dhcp_lease_files.go

@@ -0,0 +1,18 @@
+package clientinfo
+
+import "github.com/Control-D-Inc/ctrld"
+
+// clientInfoFiles specifies client info files and how to read them on supported platforms.
+var clientInfoFiles = map[string]ctrld.LeaseFileFormat{
+	"/tmp/dnsmasq.leases":                      ctrld.Dnsmasq,  // ddwrt
+	"/tmp/dhcp.leases":                         ctrld.Dnsmasq,  // openwrt
+	"/var/lib/misc/dnsmasq.leases":             ctrld.Dnsmasq,  // merlin
+	"/mnt/data/udapi-config/dnsmasq.lease":     ctrld.Dnsmasq,  // UDM Pro
+	"/data/udapi-config/dnsmasq.lease":         ctrld.Dnsmasq,  // UDR
+	"/etc/dhcpd/dhcpd-leases.log":              ctrld.Dnsmasq,  // Synology
+	"/tmp/var/lib/misc/dnsmasq.leases":         ctrld.Dnsmasq,  // Tomato
+	"/run/dnsmasq-dhcp.leases":                 ctrld.Dnsmasq,  // EdgeOS
+	"/run/dhcpd.leases":                        ctrld.IscDhcpd, // EdgeOS
+	"/var/dhcpd/var/db/dhcpd.leases":           ctrld.IscDhcpd, // Pfsense
+	"/home/pi/.router/run/dhcp/dnsmasq.leases": ctrld.Dnsmasq,  // Firewalla
+}

internal/clientinfo/dhcp_test.go

@@ -0,0 +1,88 @@
+package clientinfo
+
+import (
+	"io"
+	"strings"
+	"testing"
+)
+
+func Test_readClientInfoReader(t *testing.T) {
+	d := &dhcp{}
+	tests := []struct {
+		name     string
+		in       string
+		readFunc func(r io.Reader) error
+		mac      string
+		hostname string
+	}{
+		{
+			"good dnsmasq",
+			`1683329857 e6:20:59:b8:c1:6d 192.168.1.186 host1 01:e6:20:59:b8:c1:6d
+`,
+			d.dnsmasqReadClientInfoReader,
+			"e6:20:59:b8:c1:6d",
+			"host1",
+		},
+		{
+			"bad dnsmasq seen on UDMdream machine",
+			`1683329857 e6:20:59:b8:c1:6e 192.168.1.111 host1 01:e6:20:59:b8:c1:6e
+duid 00:01:00:01:2b:e4:2e:2c:52:52:14:26:dc:1c
+1683322985 117442354 2600:4040:b0e6:b700::111 ASDASD 00:01:00:01:2a:d0:b9:81:00:07:32:4c:1c:07
+`,
+			d.dnsmasqReadClientInfoReader,
+			"e6:20:59:b8:c1:6e",
+			"host1",
+		},
+		{
+			"isc-dhcpd good",
+			`lease 192.168.1.1 {
+    hardware ethernet 00:00:00:00:00:01;
+    client-hostname "host-1";
+}
+`,
+			d.iscDHCPReadClientInfoReader,
+			"00:00:00:00:00:01",
+			"host-1",
+		},
+		{
+			"isc-dhcpd bad dhcp",
+			`lease 192.168.1.1 {
+    hardware ethernet invalid-dhcp;
+    client-hostname "host-1";
+}
+
+lease 192.168.1.2 {
+    hardware ethernet 00:00:00:00:00:02;
+    client-hostname "host-2";
+}
+`,
+			d.iscDHCPReadClientInfoReader,
+			"00:00:00:00:00:02",
+			"host-2",
+		},
+		{
+			"",
+			`1685794060 00:00:00:00:00:04 192.168.0.209 example 00:00:00:00:00:04 9`,
+			d.dnsmasqReadClientInfoReader,
+			"00:00:00:00:00:04",
+			"example",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			d.mac2name.Delete(tc.mac)
+			if err := tc.readFunc(strings.NewReader(tc.in)); err != nil {
+				t.Errorf("readClientInfoReader() error = %v", err)
+			}
+			val, existed := d.mac2name.Load(tc.mac)
+			if !existed {
+				t.Error("client info missing")
+			}
+			hostname := val.(string)
+			if existed && hostname != tc.hostname {
+				t.Errorf("hostname mismatched, want: %q, got: %q", tc.hostname, hostname)
+			}
+		})
+	}
+}

internal/clientinfo/mdns.go

@@ -0,0 +1,209 @@
+package clientinfo
+
+import (
+	"context"
+	"errors"
+	"net"
+	"os"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/miekg/dns"
+	"tailscale.com/logtail/backoff"
+
+	"github.com/Control-D-Inc/ctrld"
+	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
+)
+
+var (
+	mdnsV4Addr = &net.UDPAddr{
+		IP:   net.ParseIP("224.0.0.251"),
+		Port: 5353,
+	}
+	mdnsV6Addr = &net.UDPAddr{
+		IP:   net.ParseIP("ff02::fb"),
+		Port: 5353,
+	}
+)
+
+type mdns struct {
+	name sync.Map // ip => hostname
+}
+
+func (m *mdns) LookupHostnameByIP(ip string) string {
+	val, ok := m.name.Load(ip)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+func (m *mdns) LookupHostnameByMac(mac string) string {
+	return ""
+}
+
+func (m *mdns) String() string {
+	return "mdns"
+}
+
+func (m *mdns) List() []string {
+	var ips []string
+	m.name.Range(func(key, value any) bool {
+		ips = append(ips, key.(string))
+		return true
+	})
+	return ips
+}
+
+func (m *mdns) init(quitCh chan struct{}) error {
+	ifaces, err := multicastInterfaces()
+	if err != nil {
+		return err
+	}
+
+	v4ConnList := make([]*net.UDPConn, 0, len(ifaces))
+	v6ConnList := make([]*net.UDPConn, 0, len(ifaces))
+	for _, iface := range ifaces {
+		if iface.Flags&net.FlagLoopback != 0 {
+			continue
+		}
+		if conn, err := net.ListenMulticastUDP("udp4", &iface, mdnsV4Addr); err == nil {
+			v4ConnList = append(v4ConnList, conn)
+			go m.readLoop(conn)
+		}
+		if ctrldnet.IPv6Available(context.Background()) {
+			if conn, err := net.ListenMulticastUDP("udp6", &iface, mdnsV6Addr); err == nil {
+				v6ConnList = append(v6ConnList, conn)
+				go m.readLoop(conn)
+			}
+		}
+	}
+
+	go m.probeLoop(v4ConnList, mdnsV4Addr, quitCh)
+	go m.probeLoop(v6ConnList, mdnsV6Addr, quitCh)
+
+	return nil
+}
+
+// probeLoop performs mdns probe actively to get hostname updates.
+func (m *mdns) probeLoop(conns []*net.UDPConn, remoteAddr net.Addr, quitCh chan struct{}) {
+	bo := backoff.NewBackoff("mdns probe", func(format string, args ...any) {}, time.Second*30)
+	for {
+		err := m.probe(conns, remoteAddr)
+		if isErrNetUnreachableOrInvalid(err) {
+			ctrld.ProxyLogger.Load().Warn().Msgf("stop probing %q: network unreachable or invalid", remoteAddr)
+			break
+		}
+		if err != nil {
+			ctrld.ProxyLogger.Load().Warn().Err(err).Msg("error while probing mdns")
+			bo.BackOff(context.Background(), errors.New("mdns probe backoff"))
+			continue
+		}
+		break
+	}
+	<-quitCh
+	for _, conn := range conns {
+		_ = conn.Close()
+	}
+}
+
+// readLoop reads from mdns connection, save/update any hostnames found.
+func (m *mdns) readLoop(conn *net.UDPConn) {
+	defer conn.Close()
+	buf := make([]byte, dns.MaxMsgSize)
+
+	for {
+		_ = conn.SetReadDeadline(time.Now().Add(time.Second * 30))
+		n, _, err := conn.ReadFromUDP(buf)
+		if err != nil {
+			if err, ok := err.(*net.OpError); ok && (err.Timeout() || err.Temporary()) {
+				continue
+			}
+			ctrld.ProxyLogger.Load().Debug().Err(err).Msg("mdns readLoop error")
+			return
+		}
+
+		var msg dns.Msg
+		if err := msg.Unpack(buf[:n]); err != nil {
+			continue
+		}
+
+		var ip, name string
+		rrs := make([]dns.RR, 0, len(msg.Answer)+len(msg.Extra))
+		rrs = append(rrs, msg.Answer...)
+		rrs = append(rrs, msg.Extra...)
+		for _, rr := range rrs {
+			switch ar := rr.(type) {
+			case *dns.A:
+				ip, name = ar.A.String(), ar.Hdr.Name
+			case *dns.AAAA:
+				ip, name = ar.AAAA.String(), ar.Hdr.Name
+			}
+			if ip != "" && name != "" {
+				name = normalizeHostname(name)
+				if val, loaded := m.name.LoadOrStore(ip, name); !loaded {
+					ctrld.ProxyLogger.Load().Debug().Msgf("found hostname: %q, ip: %q via mdns", name, ip)
+				} else {
+					old := val.(string)
+					if old != name {
+						ctrld.ProxyLogger.Load().Debug().Msgf("update hostname: %q, ip: %q, old: %q via mdns", name, ip, old)
+						m.name.Store(ip, name)
+					}
+				}
+				ip, name = "", ""
+			}
+		}
+	}
+}
+
+// probe performs mdns queries with known services.
+func (m *mdns) probe(conns []*net.UDPConn, remoteAddr net.Addr) error {
+	msg := new(dns.Msg)
+	msg.Question = make([]dns.Question, len(services))
+	msg.Compress = true
+	for i, service := range services {
+		msg.Question[i] = dns.Question{
+			Name:   dns.CanonicalName(service),
+			Qtype:  dns.TypePTR,
+			Qclass: dns.ClassINET,
+		}
+	}
+
+	buf, err := msg.Pack()
+	if err != nil {
+		return err
+	}
+	for _, conn := range conns {
+		_ = conn.SetWriteDeadline(time.Now().Add(time.Second * 30))
+		if _, werr := conn.WriteTo(buf, remoteAddr); werr != nil {
+			err = werr
+		}
+	}
+	return err
+}
+
+func multicastInterfaces() ([]net.Interface, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+	interfaces := make([]net.Interface, 0, len(ifaces))
+	for _, ifi := range ifaces {
+		if (ifi.Flags & net.FlagUp) == 0 {
+			continue
+		}
+		if (ifi.Flags & net.FlagMulticast) > 0 {
+			interfaces = append(interfaces, ifi)
+		}
+	}
+	return interfaces, nil
+}
+
+func isErrNetUnreachableOrInvalid(err error) bool {
+	var se *os.SyscallError
+	if errors.As(err, &se) {
+		return se.Err == syscall.ENETUNREACH || se.Err == syscall.EINVAL
+	}
+	return false
+}

internal/clientinfo/mdns_services.go

@@ -0,0 +1,70 @@
+package clientinfo
+
+var services = [...]string{
+	// From: https://jonathanmumm.com/tech-it/mdns-bonjour-bible-common-service-strings-for-various-vendors/
+	"_afpovertcp._tcp.local.",
+	"_airdroid._tcp.local.",
+	"_airdrop._tcp.local.",
+	"_airplay._tcp.local.",
+	"_airport._tcp.local.",
+	"_amzn-wplay._tcp.local.",
+	"_sub._apple-mobdev2._tcp.local.",
+	"_apple-mobdev2._tcp.local.",
+	"_apple-sasl._tcp.local.",
+	"_atc._tcp.local.",
+	"_sketchmirror._tcp.local.",
+	"_bp2p._tcp.local.",
+	"_Friendly._sub._bp2p._tcp.local.",
+	"_invoke._sub._bp2p._tcp.local.",
+	"_webdav._sub._bp2p._tcp.local.",
+	"_device-info._tcp.local.",
+	"_distcc._tcp.local.",
+	"_dpap._tcp.local.",
+	"_eppc._tcp.local.",
+	"_esdevice._tcp.local.",
+	"_esfileshare._tcp.local.",
+	"_ftp._tcp.local.",
+	"_googlecast._tcp.local.",
+	"_googlezone._tcp.local.",
+	"_hap._tcp.local.",
+	"_homekit._tcp.local.",
+	"_home-sharing._tcp.local.",
+	"_http._tcp.local.",
+	"_hudson._tcp.local.",
+	"_ica-networking._tcp.local.",
+	"_print._sub._ipp._tcp.local.",
+	"_cups._sub._ipps._tcp.local.",
+	"_print._sub._ipps._tcp.local.",
+	"_jenkins._tcp.local.",
+	"_KeynoteControl._tcp.local.",
+	"_keynotepair._tcp.local.",
+	"_mediaremotetv._tcp.local.",
+	"_nfs._tcp.local.",
+	"_nvstream._tcp.local.",
+	"_androidtvremote._tcp.local.",
+	"_omnistate._tcp.local.",
+	"_photoshopserver._tcp.local.",
+	"_printer._tcp.local.",
+	"_raop._tcp.local.",
+	"_readynas._tcp.local.",
+	"_rfb._tcp.local.",
+	"_physicalweb._tcp.local.",
+	"_rsp._tcp.local.",
+	"_scanner._tcp.local.",
+	"_sftp-ssh._tcp.local.",
+	"_sleep-proxy._udp.local.",
+	"_smb._tcp.local.",
+	"_spotify-connect._tcp.local.",
+	"_ssh._tcp.local.",
+	"_teamviewer._tcp.local.",
+	"_telnet._tcp.local.",
+	"_touch-able._tcp.local.",
+	"_tunnel._tcp.local.",
+	"_webdav._tcp.local.",
+	"_webdav._tcp.local.",
+	"_workstation._tcp.local.",
+	"_xserveraid._tcp.local.",
+
+	// Merlin
+	"_alexa._tcp",
+}

internal/clientinfo/merlin.go

@@ -0,0 +1,71 @@
+package clientinfo
+
+import (
+	"strings"
+	"sync"
+
+	"github.com/Control-D-Inc/ctrld/internal/router"
+	"github.com/Control-D-Inc/ctrld/internal/router/merlin"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/router/nvram"
+)
+
+const merlinNvramCustomClientListKey = "custom_clientlist"
+
+type merlinDiscover struct {
+	hostname sync.Map // mac => hostname
+}
+
+func (m *merlinDiscover) refresh() error {
+	if router.Name() != merlin.Name {
+		return nil
+	}
+	out, err := nvram.Run("get", merlinNvramCustomClientListKey)
+	if err != nil {
+		return err
+	}
+	ctrld.ProxyLogger.Load().Debug().Msg("reading Merlin custom client list")
+	m.parseMerlinCustomClientList(out)
+	return nil
+}
+
+func (m *merlinDiscover) LookupHostnameByIP(ip string) string {
+	return ""
+}
+
+func (m *merlinDiscover) LookupHostnameByMac(mac string) string {
+	val, ok := m.hostname.Load(mac)
+	if !ok {
+		return ""
+	}
+	return val.(string)
+}
+
+// "nvram get custom_clientlist" output:
+//
+// <client 1>00:00:00:00:00:01>0>4>><client 2>00:00:00:00:00:02>0>24>>...
+//
+// So to parse it, do the following steps:
+//
+//   - Split by "<"                 => entries
+//   - For each entry, split by ">" => parts
+//   - Empty parts                  => skip
+//   - Empty parts[0]               => skip empty hostname
+//   - Empty parts[1]               => skip empty MAC
+func (m *merlinDiscover) parseMerlinCustomClientList(data string) {
+	entries := strings.Split(data, "<")
+	for _, entry := range entries {
+		parts := strings.SplitN(string(entry), ">", 3)
+		if len(parts) < 2 || len(parts[0]) == 0 || len(parts[1]) == 0 {
+			continue
+		}
+		hostname := normalizeHostname(parts[0])
+		mac := strings.ToLower(parts[1])
+		m.hostname.Store(mac, hostname)
+	}
+}
+
+func (m *merlinDiscover) String() string {
+	return "merlin"
+}

internal/clientinfo/merlin_test.go

@@ -0,0 +1,82 @@
+package clientinfo
+
+import (
+	"testing"
+)
+
+func TestParseMerlinCustomClientList(t *testing.T) {
+	tests := []struct {
+		name              string
+		clientList        string
+		macList           []string
+		hostnameList      []string
+		macNotPresentList []string
+	}{
+		{
+			"normal",
+			"<client1>00:00:00:00:00:01>0>4>>",
+			[]string{"00:00:00:00:00:01"},
+			[]string{"client1"},
+			nil,
+		},
+		{
+			"multiple clients",
+			"<client1>00:00:00:00:00:01>0>4>><client2>00:00:00:00:00:02>0>24>>",
+			[]string{"00:00:00:00:00:01", "00:00:00:00:00:02"},
+			[]string{"client1", "client2"},
+			nil,
+		},
+		{
+			"empty hostname",
+			"<client1>00:00:00:00:00:01>0>4>><>00:00:00:00:00:02>0>24>>",
+			[]string{"00:00:00:00:00:01"},
+			[]string{"client1"},
+			[]string{"00:00:00:00:00:02"},
+		},
+		{
+			"empty dhcp",
+			"<client1>00:00:00:00:00:01>0>4>><client 1>>>",
+			[]string{"00:00:00:00:00:01"},
+			[]string{"client1"},
+			[]string{""},
+		},
+		{
+			"invalid",
+			"qwerty",
+			nil,
+			nil,
+			nil,
+		},
+		{
+			"empty",
+			"",
+
+			nil,
+			nil,
+			nil,
+		},
+	}
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			m := &merlinDiscover{}
+			m.parseMerlinCustomClientList(tc.clientList)
+			for i, mac := range tc.macList {
+				val, ok := m.hostname.Load(mac)
+				if !ok {
+					t.Errorf("missing hostname: %s", mac)
+				}
+				hostname := val.(string)
+				if hostname != tc.hostnameList[i] {
+					t.Errorf("hostname mismatch, want: %q, got: %q", tc.hostnameList[i], hostname)
+				}
+			}
+			for _, mac := range tc.macNotPresentList {
+				if _, ok := m.hostname.Load(mac); ok {
+					t.Errorf("mac2name address %q should not be present", mac)
+				}
+			}
+		})
+	}
+}

internal/clientinfo/ptr_lookup.go

@@ -0,0 +1,82 @@
+package clientinfo
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/miekg/dns"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+type ptrDiscover struct {
+	hostname sync.Map // ip => hostname
+	resolver ctrld.Resolver
+}
+
+func (p *ptrDiscover) refresh() error {
+	p.hostname.Range(func(key, value any) bool {
+		ip := key.(string)
+		if name := p.lookupHostname(ip); name != "" {
+			p.hostname.Store(ip, name)
+		}
+		return true
+	})
+	return nil
+}
+
+func (p *ptrDiscover) LookupHostnameByIP(ip string) string {
+	if val, ok := p.hostname.Load(ip); ok {
+		return val.(string)
+	}
+	return p.lookupHostname(ip)
+}
+func (p *ptrDiscover) LookupHostnameByMac(mac string) string {
+	return ""
+}
+
+func (p *ptrDiscover) String() string {
+	return "ptr"
+}
+
+func (p *ptrDiscover) List() []string {
+	var ips []string
+	p.hostname.Range(func(key, value any) bool {
+		ips = append(ips, key.(string))
+		return true
+	})
+	return ips
+}
+
+func (p *ptrDiscover) lookupHostnameFromCache(ip string) string {
+	if val, ok := p.hostname.Load(ip); ok {
+		return val.(string)
+	}
+	return ""
+}
+
+func (p *ptrDiscover) lookupHostname(ip string) string {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	msg := new(dns.Msg)
+	addr, err := dns.ReverseAddr(ip)
+	if err != nil {
+		ctrld.ProxyLogger.Load().Error().Err(err).Msg("invalid ip address")
+		return ""
+	}
+	msg.SetQuestion(addr, dns.TypePTR)
+	ans, err := p.resolver.Resolve(ctx, msg)
+	if err != nil {
+		ctrld.ProxyLogger.Load().Error().Err(err).Msg("could not lookup IP")
+		return ""
+	}
+	for _, rr := range ans.Answer {
+		if ptr, ok := rr.(*dns.PTR); ok {
+			hostname := normalizeHostname(ptr.Ptr)
+			p.hostname.Store(ip, hostname)
+			return hostname
+		}
+	}
+	return ""
+}

internal/controld/config.go

@@ -3,24 +3,39 @@ package controld
 import (
 	"bytes"
 	"context"
+	"crypto/tls"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net"
 	"net/http"
+	"os"
+	"strings"
 	"time"
 
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/certs"
 	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
+	"github.com/Control-D-Inc/ctrld/internal/router"
+	"github.com/Control-D-Inc/ctrld/internal/router/ddwrt"
 )
 
 const (
-	resolverDataURL   = "https://api.controld.com/utility"
+	apiDomainCom       = "api.controld.com"
-	InvalidConfigCode = 40401
+	apiDomainDev       = "api.controld.dev"
+	resolverDataURLCom = "https://api.controld.com/utility"
+	resolverDataURLDev = "https://api.controld.dev/utility"
+	InvalidConfigCode  = 40401
 )
 
 // ResolverConfig represents Control D resolver data.
 type ResolverConfig struct {
-	DOH     string   `json:"doh"`
+	DOH   string `json:"doh"`
+	Ctrld struct {
+		CustomConfig string `json:"custom_config"`
+	} `json:"ctrld"`
 	Exclude []string `json:"exclude"`
+	UID     string   `json:"uid"`
 }
 
 type utilityResponse struct {
@@ -42,29 +57,70 @@ func (u UtilityErrorResponse) Error() string {
 }
 
 type utilityRequest struct {
-	UID string `json:"uid"`
+	UID      string `json:"uid"`
+	ClientID string `json:"client_id,omitempty"`
+}
+
+type utilityOrgRequest struct {
+	ProvToken string `json:"prov_token"`
+	Hostname  string `json:"hostname"`
 }
 
 // FetchResolverConfig fetch Control D config for given uid.
-func FetchResolverConfig(uid string) (*ResolverConfig, error) {
+func FetchResolverConfig(rawUID, version string, cdDev bool) (*ResolverConfig, error) {
-	body, _ := json.Marshal(utilityRequest{UID: uid})
+	uid, clientID := ParseRawUID(rawUID)
-	req, err := http.NewRequest("POST", resolverDataURL, bytes.NewReader(body))
+	req := utilityRequest{UID: uid}
+	if clientID != "" {
+		req.ClientID = clientID
+	}
+	body, _ := json.Marshal(req)
+	return postUtilityAPI(version, cdDev, bytes.NewReader(body))
+}
+
+// FetchResolverUID fetch resolver uid from provision token.
+func FetchResolverUID(pt, version string, cdDev bool) (*ResolverConfig, error) {
+	hostname, _ := os.Hostname()
+	body, _ := json.Marshal(utilityOrgRequest{ProvToken: pt, Hostname: hostname})
+	return postUtilityAPI(version, cdDev, bytes.NewReader(body))
+}
+
+func postUtilityAPI(version string, cdDev bool, body io.Reader) (*ResolverConfig, error) {
+	apiUrl := resolverDataURLCom
+	if cdDev {
+		apiUrl = resolverDataURLDev
+	}
+	req, err := http.NewRequest("POST", apiUrl, body)
 	if err != nil {
 		return nil, fmt.Errorf("http.NewRequest: %w", err)
 	}
 	q := req.URL.Query()
 	q.Set("platform", "ctrld")
+	q.Set("version", version)
 	req.URL.RawQuery = q.Encode()
 	req.Header.Add("Content-Type", "application/json")
 	transport := http.DefaultTransport.(*http.Transport).Clone()
 	transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
-		// We experiment hanging in TLS handshake when connecting to ControlD API
+		apiDomain := apiDomainCom
-		// with ipv6. So prefer ipv4 if available.
+		if cdDev {
-		proto := "tcp6"
+			apiDomain = apiDomainDev
-		if ctrldnet.SupportsIPv4() {
-			proto = "tcp4"
 		}
-		return ctrldnet.Dialer.DialContext(ctx, proto, addr)
+		ips := ctrld.LookupIP(apiDomain)
+		if len(ips) == 0 {
+			ctrld.ProxyLogger.Load().Warn().Msgf("No IPs found for %s, connecting to %s", apiDomain, addr)
+			return ctrldnet.Dialer.DialContext(ctx, network, addr)
+		}
+		ctrld.ProxyLogger.Load().Debug().Msgf("API IPs: %v", ips)
+		_, port, _ := net.SplitHostPort(addr)
+		addrs := make([]string, len(ips))
+		for i := range ips {
+			addrs[i] = net.JoinHostPort(ips[i], port)
+		}
+		d := &ctrldnet.ParallelDialer{}
+		return d.DialContext(ctx, network, addrs)
+	}
+
+	if router.Name() == ddwrt.Name {
+		transport.TLSClientConfig = &tls.Config{RootCAs: certs.CACertPool()}
 	}
 	client := http.Client{
 		Timeout:   10 * time.Second,
@@ -90,3 +146,13 @@ func FetchResolverConfig(uid string) (*ResolverConfig, error) {
 	}
 	return &ur.Body.Resolver, nil
 }
+
+// ParseRawUID parse the input raw UID, returning real UID and ClientID.
+// The raw UID can have 2 forms:
+//
+// - <uid>
+// - <uid>/<client_id>
+func ParseRawUID(rawUID string) (string, string) {
+	uid, clientID, _ := strings.Cut(rawUID, "/")
+	return uid, clientID
+}

internal/controld/config_test.go

@@ -1,34 +1,31 @@
-//go:build controld
-
 package controld
 
 import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 )
 
-const utilityURL = "https://api.controld.com/utility"
+func Test_parseUID(t *testing.T) {
-
-func TestFetchResolverConfig(t *testing.T) {
 	tests := []struct {
-		name    string
+		name         string
-		uid     string
+		uid          string
-		wantErr bool
+		wantUID      string
+		wantClientID string
 	}{
-		{"valid", "p2", false},
+		{"empty", "", "", ""},
-		{"invalid uid", "abcd1234", true},
+		{"only uid", "abcd1234", "abcd1234", ""},
+		{"with client id", "abcd1234/clientID", "abcd1234", "clientID"},
+		{"with empty clientID", "abcd1234/", "abcd1234", ""},
 	}
+
 	for _, tc := range tests {
 		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
-			got, err := FetchResolverConfig(tc.uid)
+			gotUID, gotClientID := ParseRawUID(tc.uid)
-			require.False(t, (err != nil) != tc.wantErr, err)
+			assert.Equal(t, tc.wantUID, gotUID)
-			if !tc.wantErr {
+			assert.Equal(t, tc.wantClientID, gotClientID)
-				assert.NotEmpty(t, got.DOH)
-			}
 		})
 	}
 }

internal/controld/controld_test.go

@@ -0,0 +1,34 @@
+//go:build controld
+
+package controld
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFetchResolverConfig(t *testing.T) {
+	tests := []struct {
+		name    string
+		uid     string
+		dev     bool
+		wantErr bool
+	}{
+		{"valid com", "p2", false, false},
+		{"valid dev", "p2", true, false},
+		{"invalid uid", "abcd1234", false, true},
+	}
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			got, err := FetchResolverConfig(tc.uid, "dev-test", tc.dev)
+			require.False(t, (err != nil) != tc.wantErr, err)
+			if !tc.wantErr {
+				assert.NotEmpty(t, got.DOH)
+			}
+		})
+	}
+}

internal/dns/direct.go

@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//lint:file-ignore U1000 satisfy CI.
+//lint:file-ignore U1000 Ignore, this file is forked from upstream code.
+//lint:file-ignore ST1005 Ignore, this file is forked from upstream code.
 
 package dns
 

internal/dns/manager_linux.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//lint:file-ignore U1000 Ignore this file, it's a copy.
+
 package dns
 
 import (

internal/dns/nm.go

@@ -14,8 +14,8 @@ import (
 	"time"
 
 	"github.com/godbus/dbus/v5"
+	"github.com/josharian/native"
 	"tailscale.com/util/dnsname"
-	"tailscale.com/util/endian"
 )
 
 const (
@@ -131,7 +131,7 @@ func (m *nmManager) trySet(ctx context.Context, config OSConfig) error {
 	for _, ip := range config.Nameservers {
 		b := ip.As16()
 		if ip.Is4() {
-			dnsv4 = append(dnsv4, endian.Native.Uint32(b[12:]))
+			dnsv4 = append(dnsv4, native.Endian.Uint32(b[12:]))
 		} else {
 			dnsv6 = append(dnsv6, b[:])
 		}
@@ -267,5 +267,5 @@ func (m *nmManager) Close() error {
 }
 
 func (m *nmManager) Mode() string {
-	return "network-maanger"
+	return "network-manager"
 }

internal/dns/resolvconffile/resolvconffile.go

@@ -15,7 +15,6 @@ import (
 	"strings"
 
 	"tailscale.com/util/dnsname"
-	"tailscale.com/util/strs"
 )
 
 // Path is the canonical location of resolv.conf.
@@ -63,7 +62,7 @@ func Parse(r io.Reader) (*Config, error) {
 		line, _, _ = strings.Cut(line, "#") // remove any comments
 		line = strings.TrimSpace(line)
 
-		if s, ok := strs.CutPrefix(line, "nameserver"); ok {
+		if s, ok := strings.CutPrefix(line, "nameserver"); ok {
 			nameserver := strings.TrimSpace(s)
 			if len(nameserver) == len(s) {
 				return nil, fmt.Errorf("missing space after \"nameserver\" in %q", line)
@@ -76,7 +75,7 @@ func Parse(r io.Reader) (*Config, error) {
 			continue
 		}
 
-		if s, ok := strs.CutPrefix(line, "search"); ok {
+		if s, ok := strings.CutPrefix(line, "search"); ok {
 			domains := strings.TrimSpace(s)
 			if len(domains) == len(s) {
 				// No leading space?!

internal/net/net.go

@@ -2,9 +2,13 @@ package net
 
 import (
 	"context"
+	"errors"
 	"net"
+	"os"
+	"os/signal"
 	"sync"
 	"sync/atomic"
+	"syscall"
 	"time"
 
 	"tailscale.com/logtail/backoff"
@@ -12,18 +16,17 @@ import (
 
 const (
 	controldIPv6Test = "ipv6.controld.io"
-	controldIPv4Test = "ipv4.controld.io"
+	v4BootstrapDNS   = "76.76.2.0:53"
-	bootstrapDNS     = "76.76.2.0:53"
+	v6BootstrapDNS   = "[2606:1a40::]:53"
 )
 
 var Dialer = &net.Dialer{
 	Resolver: &net.Resolver{
 		PreferGo: true,
 		Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
-			d := net.Dialer{
+			d := ParallelDialer{}
-				Timeout: 10 * time.Second,
+			d.Timeout = 10 * time.Second
-			}
+			return d.DialContext(ctx, "udp", []string{v4BootstrapDNS, v6BootstrapDNS})
-			return d.DialContext(ctx, "udp", bootstrapDNS)
 		},
 	},
 }
@@ -37,8 +40,6 @@ var probeStackDialer = &net.Dialer{
 
 var (
 	stackOnce          atomic.Pointer[sync.Once]
-	ipv4Enabled        bool
-	ipv6Enabled        bool
 	canListenIPv6Local bool
 	hasNetworkUp       bool
 )
@@ -47,13 +48,8 @@ func init() {
 	stackOnce.Store(new(sync.Once))
 }
 
-func supportIPv4() bool {
-	_, err := probeStackDialer.Dial("tcp4", net.JoinHostPort(controldIPv4Test, "80"))
-	return err == nil
-}
-
 func supportIPv6(ctx context.Context) bool {
-	_, err := probeStackDialer.DialContext(ctx, "tcp6", net.JoinHostPort(controldIPv6Test, "80"))
+	_, err := probeStackDialer.DialContext(ctx, "tcp6", net.JoinHostPort(controldIPv6Test, "443"))
 	return err == nil
 }
 
@@ -66,17 +62,33 @@ func supportListenIPv6Local() bool {
 }
 
 func probeStack() {
-	b := backoff.NewBackoff("probeStack", func(format string, args ...any) {}, time.Minute)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go func() {
+		sigs := make(chan os.Signal, 1)
+		signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
+		<-sigs
+		cancel()
+	}()
+
+	b := backoff.NewBackoff("probeStack", func(format string, args ...any) {}, 5*time.Second)
 	for {
-		if _, err := probeStackDialer.Dial("udp", bootstrapDNS); err == nil {
+		if _, err := probeStackDialer.DialContext(ctx, "udp", v4BootstrapDNS); err == nil {
 			hasNetworkUp = true
 			break
-		} else {
-			b.BackOff(context.Background(), err)
 		}
+		if _, err := probeStackDialer.DialContext(ctx, "udp", v6BootstrapDNS); err == nil {
+			hasNetworkUp = true
+			break
+		}
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+		b.BackOff(context.Background(), errors.New("network is down"))
 	}
-	ipv4Enabled = supportIPv4()
-	ipv6Enabled = supportIPv6(context.Background())
 	canListenIPv6Local = supportListenIPv6Local()
 }
 
@@ -85,16 +97,6 @@ func Up() bool {
 	return hasNetworkUp
 }
 
-func SupportsIPv4() bool {
-	stackOnce.Load().Do(probeStack)
-	return ipv4Enabled
-}
-
-func SupportsIPv6() bool {
-	stackOnce.Load().Do(probeStack)
-	return ipv6Enabled
-}
-
 func SupportsIPv6ListenLocal() bool {
 	stackOnce.Load().Do(probeStack)
 	return canListenIPv6Local
@@ -112,3 +114,54 @@ func IsIPv6(ip string) bool {
 	parsedIP := net.ParseIP(ip)
 	return parsedIP != nil && parsedIP.To4() == nil && parsedIP.To16() != nil
 }
+
+type parallelDialerResult struct {
+	conn net.Conn
+	err  error
+}
+
+type ParallelDialer struct {
+	net.Dialer
+}
+
+func (d *ParallelDialer) DialContext(ctx context.Context, network string, addrs []string) (net.Conn, error) {
+	if len(addrs) == 0 {
+		return nil, errors.New("empty addresses")
+	}
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	done := make(chan struct{})
+	defer close(done)
+	ch := make(chan *parallelDialerResult, len(addrs))
+	var wg sync.WaitGroup
+	wg.Add(len(addrs))
+	go func() {
+		wg.Wait()
+		close(ch)
+	}()
+
+	for _, addr := range addrs {
+		go func(addr string) {
+			defer wg.Done()
+			conn, err := d.Dialer.DialContext(ctx, network, addr)
+			select {
+			case ch <- &parallelDialerResult{conn: conn, err: err}:
+			case <-done:
+				if conn != nil {
+					conn.Close()
+				}
+			}
+		}(addr)
+	}
+
+	errs := make([]error, 0, len(addrs))
+	for res := range ch {
+		if res.err == nil {
+			cancel()
+			return res.conn, res.err
+		}
+		errs = append(errs, res.err)
+	}
+	return nil, errors.Join(errs...)
+}

internal/router/ddwrt/ddwrt.go

@@ -0,0 +1,117 @@
+package ddwrt
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+	"github.com/Control-D-Inc/ctrld/internal/router/ntp"
+	"github.com/Control-D-Inc/ctrld/internal/router/nvram"
+)
+
+const Name = "ddwrt"
+
+//lint:ignore ST1005 This error is for human.
+var errDdwrtJffs2NotEnabled = errors.New(`could not install service without jffs, follow this guide to enable:
+
+https://wiki.dd-wrt.com/wiki/index.php/Journalling_Flash_File_System
+`)
+
+var nvramKvMap = map[string]string{
+	"dns_dnsmasq":     "1", // Make dnsmasq running but disable DNS ability, ctrld will replace it.
+	"dnsmasq_options": "",  // Configuration of dnsmasq set by ctrld, filled by setupDDWrt.
+	"dns_crypt":       "0", // Disable DNSCrypt.
+	"dnssec":          "0", // Disable DNSSEC.
+}
+
+type Ddwrt struct {
+	cfg *ctrld.Config
+}
+
+// New returns a router.Router for configuring/setup/run ctrld on ddwrt routers.
+func New(cfg *ctrld.Config) *Ddwrt {
+	return &Ddwrt{cfg: cfg}
+}
+
+func (d *Ddwrt) ConfigureService(config *service.Config) error {
+	if !ddwrtJff2Enabled() {
+		return errDdwrtJffs2NotEnabled
+	}
+	return nil
+}
+
+func (d *Ddwrt) Install(_ *service.Config) error {
+	return nil
+}
+
+func (d *Ddwrt) Uninstall(_ *service.Config) error {
+	return nil
+}
+
+func (d *Ddwrt) PreRun() error {
+	_ = d.Cleanup()
+	return ntp.WaitNvram()
+}
+
+func (d *Ddwrt) Setup() error {
+	if d.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	// Already setup.
+	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val == "1" {
+		return nil
+	}
+
+	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, d.cfg)
+	if err != nil {
+		return err
+	}
+
+	nvramKvMap["dnsmasq_options"] = data
+	if err := nvram.SetKV(nvramKvMap, nvram.CtrldSetupKey); err != nil {
+		return err
+	}
+
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (d *Ddwrt) Cleanup() error {
+	if d.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val != "1" {
+		return nil // was restored, nothing to do.
+	}
+
+	nvramKvMap["dnsmasq_options"] = ""
+	// Restore old configs.
+	if err := nvram.Restore(nvramKvMap, nvram.CtrldSetupKey); err != nil {
+		return err
+	}
+
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func restartDNSMasq() error {
+	if out, err := exec.Command("restart_dns").CombinedOutput(); err != nil {
+		return fmt.Errorf("restart_dns: %s, %w", string(out), err)
+	}
+	return nil
+}
+
+func ddwrtJff2Enabled() bool {
+	out, _ := nvram.Run("get", "enable_jffs2")
+	return out == "1"
+}

internal/router/dnsmasq/conf.go

@@ -0,0 +1,30 @@
+package dnsmasq
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"io"
+	"os"
+	"strings"
+)
+
+func InterfaceNameFromConfig(filename string) (string, error) {
+	buf, err := os.ReadFile(filename)
+	if err != nil {
+		return "", err
+	}
+	return interfaceNameFromReader(bytes.NewReader(buf))
+}
+
+func interfaceNameFromReader(r io.Reader) (string, error) {
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+		after, found := strings.CutPrefix(line, "interface=")
+		if found {
+			return after, nil
+		}
+	}
+	return "", errors.New("not found")
+}

internal/router/dnsmasq/conf_test.go

@@ -0,0 +1,46 @@
+package dnsmasq
+
+import (
+	"strings"
+	"testing"
+)
+
+func Test_interfaceNameFromReader(t *testing.T) {
+	tests := []struct {
+		name      string
+		in        string
+		wantIface string
+	}{
+		{
+			"good",
+			`interface=lo`,
+			"lo",
+		},
+		{
+			"multiple",
+			`interface=lo
+interface=eth0
+`,
+			"lo",
+		},
+		{
+			"no iface",
+			`cache-size=100`,
+			"",
+		},
+	}
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			ifaceName, err := interfaceNameFromReader(strings.NewReader(tc.in))
+			if tc.wantIface != "" && err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
+			if tc.wantIface != ifaceName {
+				t.Errorf("mismatched, want: %q, got: %q", tc.wantIface, ifaceName)
+			}
+		})
+	}
+}

internal/router/dnsmasq/dnsmasq.go

@@ -0,0 +1,131 @@
+package dnsmasq
+
+import (
+	"errors"
+	"html/template"
+	"net"
+	"path/filepath"
+	"strings"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+const ConfigContentTmpl = `# GENERATED BY ctrld - DO NOT MODIFY
+no-resolv
+{{- range .Upstreams}}
+server={{ .IP }}#{{ .Port }}
+{{- end}}
+{{- if .SendClientInfo}}
+add-mac
+{{- end}}
+`
+
+const MerlinPostConfPath = "/jffs/scripts/dnsmasq.postconf"
+const MerlinPostConfMarker = `# GENERATED BY ctrld - EOF`
+const MerlinPostConfTmpl = `# GENERATED BY ctrld - DO NOT MODIFY
+
+#!/bin/sh
+
+config_file="$1"
+. /usr/sbin/helper.sh
+
+pid=$(cat /tmp/ctrld.pid 2>/dev/null)
+if [ -n "$pid" ] && [ -f "/proc/${pid}/cmdline" ]; then
+  pc_delete "servers-file" "$config_file"           # no WAN DNS settings
+  pc_append "no-resolv" "$config_file"              # do not read /etc/resolv.conf
+  # use ctrld as upstream
+  pc_delete "server=" "$config_file"
+  {{- range .Upstreams}}
+  pc_append "server={{ .IP }}#{{ .Port }}" "$config_file"
+  {{- end}}
+  {{- if .SendClientInfo}}
+  pc_append "add-mac" "$config_file"                # add client mac
+  {{- end}}
+  pc_delete "dnssec" "$config_file"                 # disable DNSSEC
+  pc_delete "trust-anchor=" "$config_file"          # disable DNSSEC
+	
+  # For John fork
+  pc_delete "resolv-file" "$config_file"            # no WAN DNS settings
+
+  # Change /etc/resolv.conf, which may be changed by WAN DNS setup
+  pc_delete "nameserver" /etc/resolv.conf
+  pc_append "nameserver 127.0.0.1" /etc/resolv.conf
+
+  exit 0
+fi
+`
+
+type Upstream struct {
+	IP   string
+	Port int
+}
+
+func ConfTmpl(tmplText string, cfg *ctrld.Config) (string, error) {
+	listener := cfg.FirstListener()
+	if listener == nil {
+		return "", errors.New("missing listener")
+	}
+	ip := listener.IP
+	if ip == "0.0.0.0" || ip == "::" || ip == "" {
+		ip = "127.0.0.1"
+	}
+	upstreams := []Upstream{{IP: ip, Port: listener.Port}}
+	return confTmpl(tmplText, upstreams, cfg.HasUpstreamSendClientInfo())
+}
+
+func FirewallaConfTmpl(tmplText string, cfg *ctrld.Config) (string, error) {
+	if lc := cfg.FirstListener(); lc != nil && (lc.IP == "0.0.0.0" || lc.IP == "") {
+		return confTmpl(tmplText, firewallaUpstreams(lc.Port), cfg.HasUpstreamSendClientInfo())
+	}
+	return ConfTmpl(tmplText, cfg)
+}
+
+func confTmpl(tmplText string, upstreams []Upstream, sendClientInfo bool) (string, error) {
+	tmpl := template.Must(template.New("").Parse(tmplText))
+	var to = &struct {
+		SendClientInfo bool
+		Upstreams      []Upstream
+	}{
+		SendClientInfo: sendClientInfo,
+		Upstreams:      upstreams,
+	}
+	var sb strings.Builder
+	if err := tmpl.Execute(&sb, to); err != nil {
+		return "", err
+	}
+	return sb.String(), nil
+}
+
+func firewallaUpstreams(port int) []Upstream {
+	ifaces := FirewallaSelfInterfaces()
+	upstreams := make([]Upstream, 0, len(ifaces))
+	for _, netIface := range ifaces {
+		addrs, _ := netIface.Addrs()
+		for _, addr := range addrs {
+			if netIP, ok := addr.(*net.IPNet); ok && netIP.IP.To4() != nil {
+				upstreams = append(upstreams, Upstream{
+					IP:   netIP.IP.To4().String(),
+					Port: port,
+				})
+			}
+		}
+	}
+	return upstreams
+}
+
+// FirewallaSelfInterfaces returns list of interfaces that will be configured with default dnsmasq setup on Firewalla.
+func FirewallaSelfInterfaces() []*net.Interface {
+	matches, err := filepath.Glob("/home/pi/firerouter/etc/dnsmasq.dns.*.conf")
+	if err != nil {
+		return nil
+	}
+	ifaces := make([]*net.Interface, 0, len(matches))
+	for _, match := range matches {
+		// Trim prefix and suffix to get the iface name only.
+		ifaceName := strings.TrimSuffix(strings.TrimPrefix(match, "/home/pi/firerouter/etc/dnsmasq.dns."), ".conf")
+		if netIface, _ := net.InterfaceByName(ifaceName); netIface != nil {
+			ifaces = append(ifaces, netIface)
+		}
+	}
+	return ifaces
+}

internal/router/edgeos/edgeos.go

@@ -0,0 +1,182 @@
+package edgeos
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/kardianos/service"
+)
+
+const (
+	Name                       = "edgeos"
+	edgeOSDNSMasqConfigPath    = "/etc/dnsmasq.d/dnsmasq-zzz-ctrld.conf"
+	usgDNSMasqConfigPath       = "/etc/dnsmasq.conf"
+	usgDNSMasqBackupConfigPath = "/etc/dnsmasq.conf.bak"
+	toggleContentFilteringLink = "https://community.ui.com/questions/UDM-Pro-disable-enable-DNS-filtering/e2cc4060-e56a-4139-b200-62d7f773ff8f"
+)
+
+var ErrContentFilteringEnabled = fmt.Errorf(`the "Content Filtering" feature" is enabled, which is conflicted with ctrld.\n
+To disable it, folowing instruction here: %s`, toggleContentFilteringLink)
+
+type EdgeOS struct {
+	cfg   *ctrld.Config
+	isUSG bool
+}
+
+// New returns a router.Router for configuring/setup/run ctrld on EdgeOS routers.
+func New(cfg *ctrld.Config) *EdgeOS {
+	e := &EdgeOS{cfg: cfg}
+	e.isUSG = checkUSG()
+	return e
+}
+
+func (e *EdgeOS) ConfigureService(config *service.Config) error {
+	return nil
+}
+
+func (e *EdgeOS) Install(_ *service.Config) error {
+	// If "Content Filtering" is enabled, UniFi OS will create firewall rules to intercept all DNS queries
+	// from outside, and route those queries to separated interfaces (e.g: dnsfilter-2@if79) created by UniFi OS.
+	// Thus, those queries will never reach ctrld listener. UniFi OS does not provide any mechanism to toggle this
+	// feature via command line, so there's nothing ctrld can do to disable this feature. For now, reporting an
+	// error and guiding users to disable the feature using UniFi OS web UI.
+	if ContentFilteringEnabled() {
+		return ErrContentFilteringEnabled
+	}
+	return nil
+}
+
+func (e *EdgeOS) Uninstall(_ *service.Config) error {
+	return nil
+}
+
+func (e *EdgeOS) PreRun() error {
+	return nil
+}
+
+func (e *EdgeOS) Setup() error {
+	if e.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	if e.isUSG {
+		return e.setupUSG()
+	}
+	return e.setupUDM()
+}
+
+func (e *EdgeOS) Cleanup() error {
+	if e.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	if e.isUSG {
+		return e.cleanupUSG()
+	}
+	return e.cleanupUDM()
+}
+
+func (e *EdgeOS) setupUSG() error {
+	// On USG, dnsmasq is configured to forward queries to external provider by default.
+	// So instead of generating config in /etc/dnsmasq.d, we need to create a backup of
+	// the config, then modify it to forward queries to ctrld listener.
+
+	// Creating a backup.
+	buf, err := os.ReadFile(usgDNSMasqConfigPath)
+	if err != nil {
+		return fmt.Errorf("setupUSG: reading current config: %w", err)
+	}
+	if err := os.WriteFile(usgDNSMasqBackupConfigPath, buf, 0600); err != nil {
+		return fmt.Errorf("setupUSG: backup current config: %w", err)
+	}
+
+	// Removing all configured upstreams.
+	var sb strings.Builder
+	scanner := bufio.NewScanner(bytes.NewReader(buf))
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasPrefix(line, "server=") {
+			continue
+		}
+		if strings.HasPrefix(line, "all-servers") {
+			continue
+		}
+		sb.WriteString(line)
+	}
+
+	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, e.cfg)
+	if err != nil {
+		return err
+	}
+	sb.WriteString("\n")
+	sb.WriteString(data)
+	if err := os.WriteFile(usgDNSMasqConfigPath, []byte(sb.String()), 0644); err != nil {
+		return fmt.Errorf("setupUSG: writing dnsmasq config: %w", err)
+	}
+
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return fmt.Errorf("setupUSG: restartDNSMasq: %w", err)
+	}
+	return nil
+}
+
+func (e *EdgeOS) setupUDM() error {
+	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, e.cfg)
+	if err != nil {
+		return err
+	}
+	if err := os.WriteFile(edgeOSDNSMasqConfigPath, []byte(data), 0600); err != nil {
+		return fmt.Errorf("setupUDM: generating dnsmasq config: %w", err)
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return fmt.Errorf("setupUDM: restartDNSMasq: %w", err)
+	}
+	return nil
+}
+
+func (e *EdgeOS) cleanupUSG() error {
+	if err := os.Rename(usgDNSMasqBackupConfigPath, usgDNSMasqConfigPath); err != nil {
+		return fmt.Errorf("cleanupUSG: os.Rename: %w", err)
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return fmt.Errorf("cleanupUSG: restartDNSMasq: %w", err)
+	}
+	return nil
+}
+
+func (e *EdgeOS) cleanupUDM() error {
+	// Remove the custom dnsmasq config
+	if err := os.Remove(edgeOSDNSMasqConfigPath); err != nil {
+		return fmt.Errorf("cleanupUDM: os.Remove: %w", err)
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return fmt.Errorf("cleanupUDM: restartDNSMasq: %w", err)
+	}
+	return nil
+}
+
+func ContentFilteringEnabled() bool {
+	st, err := os.Stat("/run/dnsfilter/dnsfilter")
+	return err == nil && !st.IsDir()
+}
+
+func checkUSG() bool {
+	out, _ := exec.Command("mca-cli-op", "info").Output()
+	return bytes.Contains(out, []byte("UniFi-Gateway-"))
+}
+
+func restartDNSMasq() error {
+	if out, err := exec.Command("/etc/init.d/dnsmasq", "restart").CombinedOutput(); err != nil {
+		return fmt.Errorf("edgeosRestartDNSMasq: %s, %w", string(out), err)
+	}
+	return nil
+}

internal/router/firewalla/firewalla.go

@@ -0,0 +1,110 @@
+package firewalla
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/kardianos/service"
+)
+
+const (
+	Name = "firewalla"
+
+	firewallaDNSMasqConfigPath   = "/home/pi/.firewalla/config/dnsmasq_local/ctrld"
+	firewallaConfigPostMainDir   = "/home/pi/.firewalla/config/post_main.d"
+	firewallaCtrldInitScriptPath = "/home/pi/.firewalla/config/post_main.d/start_ctrld.sh"
+)
+
+type Firewalla struct {
+	cfg *ctrld.Config
+}
+
+// New returns a router.Router for configuring/setup/run ctrld on Firewalla routers.
+func New(cfg *ctrld.Config) *Firewalla {
+	return &Firewalla{cfg: cfg}
+}
+
+func (f *Firewalla) ConfigureService(_ *service.Config) error {
+	return nil
+}
+
+func (f *Firewalla) Install(_ *service.Config) error {
+	// Writing startup script.
+	if err := writeFirewallStartupScript(); err != nil {
+		return fmt.Errorf("writing startup script: %w", err)
+	}
+	return nil
+}
+
+func (f *Firewalla) Uninstall(_ *service.Config) error {
+	// Removing startup script.
+	if err := os.Remove(firewallaCtrldInitScriptPath); err != nil {
+		return fmt.Errorf("removing startup script: %w", err)
+	}
+	return nil
+}
+
+func (f *Firewalla) PreRun() error {
+	return nil
+}
+
+func (f *Firewalla) Setup() error {
+	if f.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	data, err := dnsmasq.FirewallaConfTmpl(dnsmasq.ConfigContentTmpl, f.cfg)
+	if err != nil {
+		return fmt.Errorf("generating dnsmasq config: %w", err)
+	}
+	if err := os.WriteFile(firewallaDNSMasqConfigPath, []byte(data), 0600); err != nil {
+		return fmt.Errorf("writing ctrld config: %w", err)
+	}
+
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return fmt.Errorf("restartDNSMasq: %w", err)
+	}
+
+	return nil
+}
+
+func (f *Firewalla) Cleanup() error {
+	if f.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	// Removing current config.
+	if err := os.Remove(firewallaDNSMasqConfigPath); err != nil {
+		return fmt.Errorf("removing ctrld config: %w", err)
+	}
+
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return fmt.Errorf("restartDNSMasq: %w", err)
+	}
+
+	return nil
+}
+
+func writeFirewallStartupScript() error {
+	if err := os.MkdirAll(firewallaConfigPostMainDir, 0775); err != nil {
+		return err
+	}
+	exe, err := os.Executable()
+	if err != nil {
+		return err
+	}
+	// This is called when "ctrld start ..." runs, so recording
+	// the same command line arguments to use in startup script.
+	argStr := strings.Join(os.Args[1:], " ")
+	script := fmt.Sprintf("#!/bin/bash\n\nsudo %q %s\n", exe, argStr)
+	return os.WriteFile(firewallaCtrldInitScriptPath, []byte(script), 0755)
+}
+
+func restartDNSMasq() error {
+	return exec.Command("systemctl", "restart", "firerouter_dns").Run()
+}

internal/router/merlin/merlin.go

@@ -0,0 +1,142 @@
+package merlin
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"unicode"
+
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+	"github.com/Control-D-Inc/ctrld/internal/router/ntp"
+	"github.com/Control-D-Inc/ctrld/internal/router/nvram"
+)
+
+const Name = "merlin"
+
+var nvramKvMap = map[string]string{
+	"dnspriv_enable": "0", // Ensure Merlin native DoT disabled.
+}
+
+type Merlin struct {
+	cfg *ctrld.Config
+}
+
+// New returns a router.Router for configuring/setup/run ctrld on Merlin routers.
+func New(cfg *ctrld.Config) *Merlin {
+	return &Merlin{cfg: cfg}
+}
+
+func (m *Merlin) ConfigureService(config *service.Config) error {
+	return nil
+}
+
+func (m *Merlin) Install(_ *service.Config) error {
+	return nil
+}
+
+func (m *Merlin) Uninstall(_ *service.Config) error {
+	return nil
+}
+
+func (m *Merlin) PreRun() error {
+	_ = m.Cleanup()
+	return ntp.WaitNvram()
+}
+
+func (m *Merlin) Setup() error {
+	if m.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	// Already setup.
+	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val == "1" {
+		return nil
+	}
+	if _, err := nvram.Run("set", nvram.CtrldSetupKey+"=1"); err != nil {
+		return err
+	}
+	buf, err := os.ReadFile(dnsmasq.MerlinPostConfPath)
+	// Already setup.
+	if bytes.Contains(buf, []byte(dnsmasq.MerlinPostConfMarker)) {
+		return nil
+	}
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	data, err := dnsmasq.ConfTmpl(dnsmasq.MerlinPostConfTmpl, m.cfg)
+	if err != nil {
+		return err
+	}
+	data = strings.Join([]string{
+		data,
+		"\n",
+		dnsmasq.MerlinPostConfMarker,
+		"\n",
+		string(buf),
+	}, "\n")
+	// Write dnsmasq post conf file.
+	if err := os.WriteFile(dnsmasq.MerlinPostConfPath, []byte(data), 0750); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+
+	if err := nvram.SetKV(nvramKvMap, nvram.CtrldSetupKey); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (m *Merlin) Cleanup() error {
+	if m.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	if val, _ := nvram.Run("get", nvram.CtrldSetupKey); val != "1" {
+		return nil // was restored, nothing to do.
+	}
+
+	// Restore old configs.
+	if err := nvram.Restore(nvramKvMap, nvram.CtrldSetupKey); err != nil {
+		return err
+	}
+
+	buf, err := os.ReadFile(dnsmasq.MerlinPostConfPath)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	// Restore dnsmasq post conf file.
+	if err := os.WriteFile(dnsmasq.MerlinPostConfPath, merlinParsePostConf(buf), 0750); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func restartDNSMasq() error {
+	if out, err := exec.Command("service", "restart_dnsmasq").CombinedOutput(); err != nil {
+		return fmt.Errorf("restart_dnsmasq: %s, %w", string(out), err)
+	}
+	return nil
+}
+
+func merlinParsePostConf(buf []byte) []byte {
+	if len(buf) == 0 {
+		return nil
+	}
+	parts := bytes.Split(buf, []byte(dnsmasq.MerlinPostConfMarker))
+	if len(parts) != 1 {
+		return bytes.TrimLeftFunc(parts[1], unicode.IsSpace)
+	}
+	return buf
+}

internal/router/merlin/merlin_test.go

@@ -0,0 +1,40 @@
+package merlin
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+)
+
+func Test_merlinParsePostConf(t *testing.T) {
+	origContent := "# foo"
+	data := strings.Join([]string{
+		dnsmasq.MerlinPostConfTmpl,
+		"\n",
+		dnsmasq.MerlinPostConfMarker,
+		"\n",
+	}, "\n")
+
+	tests := []struct {
+		name     string
+		data     string
+		expected string
+	}{
+		{"empty", "", ""},
+		{"no ctrld", origContent, origContent},
+		{"ctrld with data", data + origContent, origContent},
+		{"ctrld without data", data, ""},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			//t.Parallel()
+			if got := merlinParsePostConf([]byte(tc.data)); !bytes.Equal(got, []byte(tc.expected)) {
+				t.Errorf("unexpected result, want: %q, got: %q", tc.expected, string(got))
+			}
+		})
+	}
+}

internal/router/ntp/ntp.go

@@ -0,0 +1,49 @@
+package ntp
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"os/exec"
+	"time"
+
+	"tailscale.com/logtail/backoff"
+
+	"github.com/Control-D-Inc/ctrld/internal/router/nvram"
+)
+
+// WaitNvram waits NTP synced by checking "ntp_ready" value using nvram.
+func WaitNvram() error {
+	// Wait until `ntp_ready=1` set.
+	b := backoff.NewBackoff("ntp.Wait", func(format string, args ...any) {}, 10*time.Second)
+	for {
+		// ddwrt use "ntp_done": https://github.com/mirror/dd-wrt/blob/a08c693527ab3204bf7bebd408a7c9a83b6ede47/src/router/rc/ntp.c#L100
+		for _, key := range []string{"ntp_ready", "ntp_done"} {
+			out, err := nvram.Run("get", key)
+			if err != nil {
+				return fmt.Errorf("PreStart: nvram: %w", err)
+			}
+			if out == "1" {
+				return nil
+			}
+		}
+		b.BackOff(context.Background(), errors.New("ntp not ready"))
+	}
+}
+
+// WaitUpstart waits NTP synced by checking upstart task "ntpsync" is in "stop/waiting" state.
+func WaitUpstart() error {
+	// Wait until `initctl status ntpsync` returns stop state.
+	b := backoff.NewBackoff("ntp.WaitUpstart", func(format string, args ...any) {}, 10*time.Second)
+	for {
+		out, err := exec.Command("initctl", "status", "ntpsync").CombinedOutput()
+		if err != nil {
+			return fmt.Errorf("exec.Command: %w", err)
+		}
+		if bytes.Contains(out, []byte("stop/waiting")) {
+			return nil
+		}
+		b.BackOff(context.Background(), errors.New("ntp not ready"))
+	}
+}

internal/router/nvram/nvram.go

@@ -0,0 +1,89 @@
+package nvram
+
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+const (
+	CtrldKeyPrefix  = "ctrld_"
+	CtrldSetupKey   = "ctrld_setup"
+	CtrldInstallKey = "ctrld_install"
+	RCStartupKey    = "rc_startup"
+)
+
+// Run runs the given nvram command.
+func Run(args ...string) (string, error) {
+	cmd := exec.Command("nvram", args...)
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		return "", fmt.Errorf("%s:%w", stderr.String(), err)
+	}
+	return strings.TrimSpace(stdout.String()), nil
+}
+
+/*
+NOTE:
+  - For Openwrt, DNSSEC is not included in default dnsmasq (require dnsmasq-full).
+  - For Merlin, DNSSEC is configured during postconf script (see merlinDNSMasqPostConfTmpl).
+  - For Ubios UDM Pro/Dream Machine, DNSSEC is not included in their dnsmasq package:
+    +https://community.ui.com/questions/Implement-DNSSEC-into-UniFi/951c72b0-4d88-4c86-9174-45417bd2f9ca
+    +https://community.ui.com/questions/Enable-DNSSEC-for-Unifi-Dream-Machine-FW-updates/e68e367c-d09b-4459-9444-18908f7c1ea1
+*/
+
+// SetKV writes the given key/value from map to nvram.
+// The given setupKey is set to 1 to indicates key/value set.
+func SetKV(m map[string]string, setupKey string) error {
+	// Backup current value, store ctrld's configs.
+	for key, value := range m {
+		old, err := Run("get", key)
+		if err != nil {
+			return fmt.Errorf("%s: %w", old, err)
+		}
+		if out, err := Run("set", CtrldKeyPrefix+key+"="+old); err != nil {
+			return fmt.Errorf("%s: %w", out, err)
+		}
+		if out, err := Run("set", key+"="+value); err != nil {
+			return fmt.Errorf("%s: %w", out, err)
+		}
+	}
+
+	if out, err := Run("set", setupKey+"=1"); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	// Commit.
+	if out, err := Run("commit"); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	return nil
+}
+
+// Restore restores the old value of given key from map m.
+// The given setupKey is set to 0 to indicates key/value restored.
+func Restore(m map[string]string, setupKey string) error {
+	// Restore old configs.
+	for key := range m {
+		ctrldKey := CtrldKeyPrefix + key
+		old, err := Run("get", ctrldKey)
+		if err != nil {
+			return fmt.Errorf("%s: %w", old, err)
+		}
+		_, _ = Run("unset", ctrldKey)
+		if out, err := Run("set", key+"="+old); err != nil {
+			return fmt.Errorf("%s: %w", out, err)
+		}
+	}
+
+	if out, err := Run("unset", setupKey); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	// Commit.
+	if out, err := Run("commit"); err != nil {
+		return fmt.Errorf("%s: %w", out, err)
+	}
+	return nil
+}

internal/router/openwrt/openwrt.go

@@ -0,0 +1,107 @@
+package openwrt
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+const (
+	Name                     = "openwrt"
+	openwrtDNSMasqConfigPath = "/tmp/dnsmasq.d/ctrld.conf"
+)
+
+var errUCIEntryNotFound = errors.New("uci: Entry not found")
+
+type Openwrt struct {
+	cfg *ctrld.Config
+}
+
+// New returns a router.Router for configuring/setup/run ctrld on Openwrt routers.
+func New(cfg *ctrld.Config) *Openwrt {
+	return &Openwrt{cfg: cfg}
+}
+
+func (o *Openwrt) ConfigureService(svc *service.Config) error {
+	svc.Option["SysvScript"] = openWrtScript
+	return nil
+}
+
+func (o *Openwrt) Install(config *service.Config) error {
+	return exec.Command("/etc/init.d/ctrld", "enable").Run()
+}
+
+func (o *Openwrt) Uninstall(config *service.Config) error {
+	return nil
+}
+
+func (o *Openwrt) PreRun() error {
+	return nil
+}
+
+func (o *Openwrt) Setup() error {
+	if o.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	data, err := dnsmasq.ConfTmpl(dnsmasq.ConfigContentTmpl, o.cfg)
+	if err != nil {
+		return err
+	}
+	if err := os.WriteFile(openwrtDNSMasqConfigPath, []byte(data), 0600); err != nil {
+		return err
+	}
+	// Commit.
+	if _, err := uci("commit"); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (o *Openwrt) Cleanup() error {
+	if o.cfg.FirstListener().IsDirectDnsListener() {
+		return nil
+	}
+	// Remove the custom dnsmasq config
+	if err := os.Remove(openwrtDNSMasqConfigPath); err != nil {
+		return err
+	}
+	// Restart dnsmasq service.
+	if err := restartDNSMasq(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func restartDNSMasq() error {
+	if out, err := exec.Command("/etc/init.d/dnsmasq", "restart").CombinedOutput(); err != nil {
+		return fmt.Errorf("%s: %w", string(out), err)
+	}
+	return nil
+}
+
+func uci(args ...string) (string, error) {
+	cmd := exec.Command("uci", args...)
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		if strings.HasPrefix(stderr.String(), errUCIEntryNotFound.Error()) {
+			return "", errUCIEntryNotFound
+		}
+		return "", fmt.Errorf("%s:%w", stderr.String(), err)
+	}
+	return strings.TrimSpace(stdout.String()), nil
+}

internal/router/openwrt/procd.go

@@ -0,0 +1,24 @@
+package openwrt
+
+const openWrtScript = `#!/bin/sh /etc/rc.common
+USE_PROCD=1
+# After network starts
+START=21
+# Before network stops
+STOP=89
+cmd="{{.Path}}{{range .Arguments}} {{.|cmd}}{{end}}"
+name="{{.Name}}"
+pid_file="/var/run/${name}.pid"
+
+start_service() {
+    echo "Starting ${name}"
+    procd_open_instance
+    procd_set_param command ${cmd}
+    procd_set_param respawn             # respawn automatically if something died
+    procd_set_param stdout 1            # forward stdout of the command to logd
+    procd_set_param stderr 1            # same for stderr
+    procd_set_param pidfile ${pid_file} # write a pid file on instance start and remove it on stop
+    procd_close_instance
+    echo "${name} has been started"
+}
+`

internal/router/os_freebsd.go

@@ -0,0 +1,160 @@
+package router
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"text/template"
+
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+const (
+	osName        = "freebsd"
+	rcPath        = "/usr/local/etc/rc.d"
+	rcConfPath    = "/etc/rc.conf.d/"
+	unboundRcPath = rcPath + "/unbound"
+	dnsmasqRcPath = rcPath + "/dnsmasq"
+)
+
+func newOsRouter(cfg *ctrld.Config, cdMode bool) Router {
+	return &osRouter{cfg: cfg, cdMode: cdMode}
+}
+
+type osRouter struct {
+	cfg     *ctrld.Config
+	svcName string
+	// cdMode indicates whether the router will configure ctrld in cd mode (aka --cd=<uid>).
+	// When ctrld is running on freebsd-like routers, and there's process running on port 53
+	// in cd mode, ctrld will attempt to kill the process and become direct listener.
+	// See details implemenation in osRouter.PreRun method.
+	cdMode bool
+}
+
+func (or *osRouter) ConfigureService(svc *service.Config) error {
+	svc.Option["SysvScript"] = bsdInitScript
+	or.svcName = svc.Name
+	rcFile := filepath.Join(rcConfPath, or.svcName)
+	var to = &struct {
+		Name string
+	}{
+		or.svcName,
+	}
+
+	f, err := os.Create(rcFile)
+	if err != nil {
+		return fmt.Errorf("os.Create: %w", err)
+	}
+	defer f.Close()
+	if err := template.Must(template.New("").Parse(rcConfTmpl)).Execute(f, to); err != nil {
+		return err
+	}
+	return f.Close()
+}
+
+func (or *osRouter) Install(_ *service.Config) error {
+	if isPfsense() {
+		// pfsense need ".sh" extension for script to be run at boot.
+		// See: https://docs.netgate.com/pfsense/en/latest/development/boot-commands.html#shell-script-option
+		oldname := filepath.Join(rcPath, or.svcName)
+		newname := filepath.Join(rcPath, or.svcName+".sh")
+		_ = os.Remove(newname)
+		if err := os.Symlink(oldname, newname); err != nil {
+			return fmt.Errorf("os.Symlink: %w", err)
+		}
+	}
+	return nil
+}
+
+func (or *osRouter) Uninstall(_ *service.Config) error {
+	rcFiles := []string{filepath.Join(rcConfPath, or.svcName)}
+	if isPfsense() {
+		rcFiles = append(rcFiles, filepath.Join(rcPath, or.svcName+".sh"))
+	}
+	for _, filename := range rcFiles {
+		if err := os.Remove(filename); err != nil {
+			return fmt.Errorf("os.Remove: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func (or *osRouter) PreRun() error {
+	if or.cdMode {
+		addr := "0.0.0.0:53"
+		udpLn, udpErr := net.ListenPacket("udp", addr)
+		if udpLn != nil {
+			udpLn.Close()
+		}
+		tcpLn, tcpErr := net.Listen("tcp", addr)
+		if tcpLn != nil {
+			tcpLn.Close()
+		}
+		// If we could not listen on :53 for any reason, try killing unbound/dnsmasq, become direct listener
+		if udpErr != nil || tcpErr != nil {
+			_ = exec.Command("killall", "unbound").Run()
+			_ = exec.Command("killall", "dnsmasq").Run()
+		}
+	}
+	return nil
+}
+
+func (or *osRouter) Setup() error {
+	return nil
+}
+
+func (or *osRouter) Cleanup() error {
+	if or.cdMode {
+		_ = exec.Command(unboundRcPath, "onerestart").Run()
+		_ = exec.Command(dnsmasqRcPath, "onerestart").Run()
+	}
+	return nil
+}
+
+func isPfsense() bool {
+	b, err := os.ReadFile("/etc/platform")
+	return err == nil && bytes.HasPrefix(b, []byte("pfSense"))
+}
+
+const bsdInitScript = `#!/bin/sh
+
+# PROVIDE: {{.Name}}
+# REQUIRE: SERVERS
+# REQUIRE: unbound dnsmasq securelevel
+# KEYWORD: shutdown
+
+. /etc/rc.subr
+
+name="{{.Name}}"
+rcvar="${name}_enable"
+{{.Name}}_env="IS_DAEMON=1"
+pidfile="/var/run/${name}.pid"
+child_pidfile="/var/run/${name}_child.pid"
+command="/usr/sbin/daemon"
+daemon_args="-P ${pidfile} -p ${child_pidfile} -t \"${name}: daemon\"{{if .WorkingDirectory}} -c {{.WorkingDirectory}}{{end}}"
+command_args="${daemon_args} {{.Path}}{{range .Arguments}} {{.}}{{end}}"
+
+stop_cmd="ctrld_stop"
+
+ctrld_stop() {
+  pid=$(cat ${pidfile})
+  child_pid=$(cat ${child_pidfile})
+  if [ -e "${child_pidfile}" ]; then
+    kill -s TERM "${child_pid}"
+    wait_for_pids "${child_pid}" "${pidfile}"
+  fi
+}
+
+load_rc_config "${name}"
+run_rc_command "$1"
+`
+
+var rcConfTmpl = `# {{.Name}}
+{{.Name}}_enable="YES"
+`

internal/router/os_others.go

@@ -0,0 +1,41 @@
+//go:build !freebsd
+
+package router
+
+import (
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+const osName = ""
+
+func newOsRouter(cfg *ctrld.Config, cdMode bool) Router {
+	return &osRouter{}
+}
+
+type osRouter struct{}
+
+func (d *osRouter) ConfigureService(_ *service.Config) error {
+	return nil
+}
+
+func (d *osRouter) Install(_ *service.Config) error {
+	return nil
+}
+
+func (d *osRouter) Uninstall(_ *service.Config) error {
+	return nil
+}
+
+func (d *osRouter) PreRun() error {
+	return nil
+}
+
+func (d *osRouter) Setup() error {
+	return nil
+}
+
+func (d *osRouter) Cleanup() error {
+	return nil
+}

internal/router/router.go

@@ -0,0 +1,242 @@
+package router
+
+import (
+	"bytes"
+	"crypto/x509"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sync/atomic"
+
+	"github.com/kardianos/service"
+
+	"github.com/Control-D-Inc/ctrld"
+	"github.com/Control-D-Inc/ctrld/internal/certs"
+	"github.com/Control-D-Inc/ctrld/internal/router/ddwrt"
+	"github.com/Control-D-Inc/ctrld/internal/router/dnsmasq"
+	"github.com/Control-D-Inc/ctrld/internal/router/edgeos"
+	"github.com/Control-D-Inc/ctrld/internal/router/firewalla"
+	"github.com/Control-D-Inc/ctrld/internal/router/merlin"
+	"github.com/Control-D-Inc/ctrld/internal/router/openwrt"
+	"github.com/Control-D-Inc/ctrld/internal/router/synology"
+	"github.com/Control-D-Inc/ctrld/internal/router/tomato"
+	"github.com/Control-D-Inc/ctrld/internal/router/ubios"
+)
+
+// Service is the interface to manage ctrld service on router.
+type Service interface {
+	// ConfigureService performs works for installing ctrla as a service on router.
+	ConfigureService(*service.Config) error
+	// Install performs necessary works after service.Install done.
+	Install(*service.Config) error
+	// Uninstall performs necessary works after service.Uninstallation done.
+	Uninstall(*service.Config) error
+}
+
+// Router is the interface for managing ctrld running on router.
+type Router interface {
+	Service
+
+	// PreRun performs works need to be done before ctrld being run on router.
+	// Implementation should only return if the pre-condition was met (e.g: ntp synced).
+	PreRun() error
+	// Setup configures ctrld to be run on the router.
+	Setup() error
+	// Cleanup cleans up works setup on router by ctrld.
+	Cleanup() error
+}
+
+// New returns new Router interface.
+func New(cfg *ctrld.Config, cdMode bool) Router {
+	switch Name() {
+	case ddwrt.Name:
+		return ddwrt.New(cfg)
+	case merlin.Name:
+		return merlin.New(cfg)
+	case openwrt.Name:
+		return openwrt.New(cfg)
+	case edgeos.Name:
+		return edgeos.New(cfg)
+	case ubios.Name:
+		return ubios.New(cfg)
+	case synology.Name:
+		return synology.New(cfg)
+	case tomato.Name:
+		return tomato.New(cfg)
+	case firewalla.Name:
+		return firewalla.New(cfg)
+	}
+	return newOsRouter(cfg, cdMode)
+}
+
+// IsGLiNet reports whether the router is an GL.iNet router.
+func IsGLiNet() bool {
+	if Name() != openwrt.Name {
+		return false
+	}
+	buf, _ := os.ReadFile("/proc/version")
+	// The output of /proc/version contains "(glinet@glinet)".
+	return bytes.Contains(buf, []byte(" (glinet"))
+}
+
+// IsOldOpenwrt reports whether the router is an "old" version of Openwrt,
+// aka versions which don't have "service" command.
+func IsOldOpenwrt() bool {
+	if Name() != openwrt.Name {
+		return false
+	}
+	cmd, _ := exec.LookPath("service")
+	return cmd == ""
+}
+
+var routerPlatform atomic.Pointer[router]
+
+type router struct {
+	name string
+}
+
+// Name returns name of the router platform.
+func Name() string {
+	if r := routerPlatform.Load(); r != nil {
+		return r.name
+	}
+	r := &router{}
+	r.name = distroName()
+	routerPlatform.Store(r)
+	return r.name
+}
+
+// DefaultInterfaceName returns the default interface name of the current router.
+func DefaultInterfaceName() string {
+	switch Name() {
+	case ubios.Name:
+		return "lo"
+	}
+	return ""
+}
+
+// LocalResolverIP returns the IP that could be used as nameserver in /etc/resolv.conf file.
+func LocalResolverIP() string {
+	var iface string
+	switch Name() {
+	case edgeos.Name:
+		// On EdgeOS, dnsmasq is run with "--local-service", so we need to get
+		// the proper interface from dnsmasq config.
+		if name, _ := dnsmasq.InterfaceNameFromConfig("/etc/dnsmasq.conf"); name != "" {
+			iface = name
+		}
+	case firewalla.Name:
+		// On Firewalla, the lo interface is excluded in all dnsmasq settings of all interfaces.
+		// Thus, we use "br0" as the nameserver in /etc/resolv.conf file.
+		iface = "br0"
+	}
+	if netIface, _ := net.InterfaceByName(iface); netIface != nil {
+		addrs, _ := netIface.Addrs()
+		for _, addr := range addrs {
+			if netIP, ok := addr.(*net.IPNet); ok && netIP.IP.To4() != nil {
+				return netIP.IP.To4().String()
+			}
+		}
+	}
+	return ""
+}
+
+// HomeDir returns the home directory of ctrld on current router.
+func HomeDir() (string, error) {
+	switch Name() {
+	case ddwrt.Name, merlin.Name, tomato.Name:
+		exe, err := os.Executable()
+		if err != nil {
+			return "", err
+		}
+		return filepath.Dir(exe), nil
+	}
+	return "", nil
+}
+
+// CertPool returns the system certificate pool of the current router.
+func CertPool() *x509.CertPool {
+	if Name() == ddwrt.Name {
+		return certs.CACertPool()
+	}
+	return nil
+}
+
+// CanListenLocalhost reports whether the ctrld can listen on localhost with current host.
+func CanListenLocalhost() bool {
+	switch {
+	case Name() == firewalla.Name:
+		return false
+	default:
+		return true
+	}
+}
+
+// ServiceDependencies returns list of dependencies that ctrld services needs on this router.
+// See https://pkg.go.dev/github.com/kardianos/service#Config for list format.
+func ServiceDependencies() []string {
+	if Name() == edgeos.Name {
+		// On EdeOS, ctrld needs to start after vyatta-dhcpd, so it can read leases file.
+		return []string{
+			"Wants=vyatta-dhcpd.service",
+			"After=vyatta-dhcpd.service",
+			"Wants=dnsmasq.service",
+		}
+	}
+	return nil
+}
+
+// SelfInterfaces return list of *net.Interface that will be source of requests from router itself.
+func SelfInterfaces() []*net.Interface {
+	switch Name() {
+	case firewalla.Name:
+		return dnsmasq.FirewallaSelfInterfaces()
+	default:
+		return nil
+	}
+}
+
+func distroName() string {
+	switch {
+	case bytes.HasPrefix(unameO(), []byte("DD-WRT")):
+		return ddwrt.Name
+	case bytes.HasPrefix(unameO(), []byte("ASUSWRT-Merlin")):
+		return merlin.Name
+	case haveFile("/etc/openwrt_version"):
+		return openwrt.Name
+	case haveDir("/data/unifi"):
+		return ubios.Name
+	case bytes.HasPrefix(unameU(), []byte("synology")):
+		return synology.Name
+	case bytes.HasPrefix(unameO(), []byte("Tomato")):
+		return tomato.Name
+	case haveDir("/config/scripts/post-config.d"):
+		return edgeos.Name
+	case haveFile("/etc/ubnt/init/vyatta-router"):
+		return edgeos.Name // For 2.x
+	case haveFile("/etc/firewalla_release"):
+		return firewalla.Name
+	}
+	return osName
+}
+
+func haveFile(file string) bool {
+	_, err := os.Stat(file)
+	return err == nil
+}
+
+func haveDir(dir string) bool {
+	fi, _ := os.Stat(dir)
+	return fi != nil && fi.IsDir()
+}
+
+func unameO() []byte {
+	out, _ := exec.Command("uname", "-o").Output()
+	return out
+}
+
+func unameU() []byte {
+	out, _ := exec.Command("uname", "-u").Output()
+	return out
+}