feat: add --rfc1918 flag for explicit LAN client support

Make RFC1918 listener spawning opt-in via --rfc1918 flag instead of automatic behavior.
This allows users to explicitly control when ctrld listens on private network addresses
to receive DNS queries from LAN clients, improving security and configurability.

Refactor network interface detection to better distinguish between physical and virtual
interfaces, ensuring only real hardware interfaces are used for RFC1918 address binding.
This commit is contained in:
Cuong Manh Le
2025-09-24 17:02:16 +07:00
committed by Cuong Manh Le
parent ed826f7a95
commit f7c124d99d
10 changed files with 92 additions and 3 deletions
+1
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@@ -50,6 +50,7 @@ func InitRunCmd(rootCmd *cobra.Command) *cobra.Command {
runCmd.Flags().StringVarP(&iface, "iface", "", "", `Update DNS setting for iface, "auto" means the default interface gateway`)
_ = runCmd.Flags().MarkHidden("iface")
runCmd.Flags().StringVarP(&cdUpstreamProto, "proto", "", ctrld.ResolverTypeDOH, `Control D upstream type, either "doh" or "doh3"`)
runCmd.Flags().BoolVarP(&rfc1918, "rfc1918", "", false, "Listen on RFC1918 addresses when 127.0.0.1 is the only listener")
runCmd.FParseErrWhitelist = cobra.FParseErrWhitelist{UnknownFlags: true}
rootCmd.AddCommand(runCmd)
+1
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@@ -348,6 +348,7 @@ NOTE: running "ctrld start" without any arguments will start already installed c
startCmd.Flags().BoolVarP(&skipSelfChecks, "skip_self_checks", "", false, `Skip self checks after installing ctrld service`)
startCmd.Flags().BoolVarP(&startOnly, "start_only", "", false, "Do not install new service")
_ = startCmd.Flags().MarkHidden("start_only")
startCmd.Flags().BoolVarP(&rfc1918, "rfc1918", "", false, "Listen on RFC1918 addresses when 127.0.0.1 is the only listener")
// Start command alias
startCmdAlias := &cobra.Command{
+3 -1
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@@ -142,6 +142,8 @@ func (p *prog) startListeners(ctx context.Context, cfg *ctrld.ListenerConfig, ha
})
}
// When we spawn a listener on 127.0.0.1, also spawn listeners on the RFC1918 addresses of the machine
// if explicitly set via setting rfc1918 flag, so ctrld could receive queries from LAN clients.
if needRFC1918Listeners(cfg) {
logger.Debug().Str("protocol", proto).Msg("Starting RFC1918 listeners")
g.Go(func() error {
@@ -1279,7 +1281,7 @@ func (p *prog) queryFromSelf(ip string) bool {
// needRFC1918Listeners reports whether ctrld need to spawn listener for RFC 1918 addresses.
// This is helpful for non-desktop platforms to receive queries from LAN clients.
func needRFC1918Listeners(lc *ctrld.ListenerConfig) bool {
return lc.IP == "127.0.0.1" && lc.Port == 53 && !ctrld.IsDesktopPlatform()
return rfc1918 && lc.IP == "127.0.0.1" && lc.Port == 53
}
// ipFromARPA parses a FQDN arpa domain and return the IP address if valid.
+1
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@@ -41,6 +41,7 @@ var (
skipSelfChecks bool
cleanup bool
startOnly bool
rfc1918 bool
mainLog atomic.Pointer[ctrld.Logger]
consoleWriter zapcore.Core
-104
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@@ -1,104 +0,0 @@
package cli
import (
"maps"
"strings"
"testing"
"github.com/stretchr/testify/assert"
)
const listnetworkserviceorderOutput = `
(1) USB 10/100/1000 LAN 2
(Hardware Port: USB 10/100/1000 LAN, Device: en7)
(2) Ethernet
(Hardware Port: Ethernet, Device: en0)
(3) Wi-Fi
(Hardware Port: Wi-Fi, Device: en1)
(4) Bluetooth PAN
(Hardware Port: Bluetooth PAN, Device: en4)
(5) Thunderbolt Bridge
(Hardware Port: Thunderbolt Bridge, Device: bridge0)
(6) kernal
(Hardware Port: com.wireguard.macos, Device: )
(7) WS BT
(Hardware Port: com.wireguard.macos, Device: )
(8) ca-001-stg
(Hardware Port: com.wireguard.macos, Device: )
(9) ca-001-stg-2
(Hardware Port: com.wireguard.macos, Device: )
`
func Test_networkServiceName(t *testing.T) {
tests := []struct {
ifaceName string
networkServiceName string
}{
{"en7", "USB 10/100/1000 LAN 2"},
{"en0", "Ethernet"},
{"en1", "Wi-Fi"},
{"en4", "Bluetooth PAN"},
{"bridge0", "Thunderbolt Bridge"},
}
for _, tc := range tests {
tc := tc
t.Run(tc.ifaceName, func(t *testing.T) {
t.Parallel()
name := networkServiceName(tc.ifaceName, strings.NewReader(listnetworkserviceorderOutput))
assert.Equal(t, tc.networkServiceName, name)
})
}
}
const listallhardwareportsOutput = `
Hardware Port: Ethernet Adapter (en6)
Device: en6
Ethernet Address: 3a:3e:fc:1e:ab:41
Hardware Port: Ethernet Adapter (en7)
Device: en7
Ethernet Address: 3a:3e:fc:1e:ab:42
Hardware Port: Thunderbolt Bridge
Device: bridge0
Ethernet Address: 36:21:bb:3a:7a:40
Hardware Port: Wi-Fi
Device: en0
Ethernet Address: a0:78:17:68:56:3f
Hardware Port: Thunderbolt 1
Device: en1
Ethernet Address: 36:21:bb:3a:7a:40
Hardware Port: Thunderbolt 2
Device: en2
Ethernet Address: 36:21:bb:3a:7a:44
VLAN Configurations
===================
`
func Test_parseListAllHardwarePorts(t *testing.T) {
expected := map[string]struct{}{
"en0": {},
"en1": {},
"en2": {},
"en6": {},
"en7": {},
"bridge0": {},
}
m := parseListAllHardwarePorts(strings.NewReader(listallhardwareportsOutput))
if !maps.Equal(m, expected) {
t.Errorf("unexpected output, want: %v, got: %v", expected, m)
}
}