Use discover_ptr_endpoints for PTR resolver

cmd/cli/dns_proxy.go

@@ -285,6 +285,12 @@ func (p *prog) proxy(ctx context.Context, upstreams []string, failoverRcodes []i
 	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 upstreamConfig.Type == ctrld.ResolverTypePrivate {
+			if r := p.ptrResolver; r != nil {
+				ctrld.ProxyLogger.Load().Debug().Msgf("using nameservers %v for PTR resolver", p.cfg.Service.DiscoverPtrEndpoints)
+				dnsResolver = r
+			}
+		}
 		if err != nil {
 			ctrld.Log(ctx, mainLog.Load().Error().Err(err), "failed to create resolver")
 			return nil, err

cmd/cli/prog.go

@@ -62,6 +62,7 @@ type prog struct {
 	ciTable     *clientinfo.Table
 	um          *upstreamMonitor
 	router      router.Router
+	ptrResolver ctrld.Resolver
 
 	loopMu sync.Mutex
 	loop   map[string]bool
@@ -229,6 +230,9 @@ func (p *prog) run(reload bool, reloadCh chan struct{}) {
 			p.cache = cacher
 		}
 	}
+	if r := p.cfg.Service.PtrResolver(); r != nil {
+		p.ptrResolver = r
+	}
 
 	var wg sync.WaitGroup
 	wg.Add(len(p.cfg.Listener))

config.go

@@ -196,6 +196,29 @@ type ServiceConfig struct {
 	AllocateIP            bool     `mapstructure:"-" toml:"-"`
 }
 
+// PtrResolver returns a Resolver used for PTR lookup, based on ServiceConfig.DiscoverPtrEndpoints value.
+func (s ServiceConfig) PtrResolver() Resolver {
+	if len(s.DiscoverPtrEndpoints) > 0 {
+		nss := make([]string, 0, len(s.DiscoverPtrEndpoints))
+		for _, ns := range s.DiscoverPtrEndpoints {
+			host, port := ns, "53"
+			if h, p, err := net.SplitHostPort(ns); err == nil {
+				host, port = h, p
+			}
+			// Only use valid ip:port pair.
+			if _, portErr := strconv.Atoi(port); portErr == nil && port != "0" && net.ParseIP(host) != nil {
+				nss = append(nss, net.JoinHostPort(host, port))
+			} else {
+				ProxyLogger.Load().Warn().Msgf("ignoring invalid nameserver for PTR resolver: %q", ns)
+			}
+		}
+		if len(nss) > 0 {
+			return NewResolverWithNameserver(nss)
+		}
+	}
+	return nil
+}
+
 // NetworkConfig specifies configuration for networks where ctrld will handle requests.
 type NetworkConfig struct {
 	Name   string       `mapstructure:"name" toml:"name,omitempty"`

internal/clientinfo/client_info.go

@@ -3,9 +3,7 @@ package clientinfo
 import (
 	"context"
 	"fmt"
-	"net"
 	"net/netip"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -185,24 +183,9 @@ func (t *Table) init() {
 	// PTR lookup.
 	if t.discoverPTR() {
 		t.ptr = &ptrDiscover{resolver: ctrld.NewPrivateResolver()}
-		if len(t.svcCfg.DiscoverPtrEndpoints) > 0 {
+		if r := t.svcCfg.PtrResolver(); r != nil {
-			nss := make([]string, 0, len(t.svcCfg.DiscoverPtrEndpoints))
+			ctrld.ProxyLogger.Load().Debug().Msgf("using nameservers %v for PTR discover", t.svcCfg.DiscoverPtrEndpoints)
-			for _, ns := range t.svcCfg.DiscoverPtrEndpoints {
+			t.ptr.resolver = r
-				host, port := ns, "53"
-				if h, p, err := net.SplitHostPort(ns); err == nil {
-					host, port = h, p
-				}
-				// Only use valid ip:port pair.
-				if _, portErr := strconv.Atoi(port); portErr == nil && port != "0" && net.ParseIP(host) != nil {
-					nss = append(nss, net.JoinHostPort(host, port))
-				} else {
-					ctrld.ProxyLogger.Load().Warn().Msgf("ignoring invalid nameserver for ptr discover: %q", ns)
-				}
-			}
-			if len(nss) > 0 {
-				t.ptr.resolver = ctrld.NewResolverWithNameserver(nss)
-				ctrld.ProxyLogger.Load().Debug().Msgf("using nameservers %v for ptr discovery", nss)
-			}
 		}
 		ctrld.ProxyLogger.Load().Debug().Msg("start ptr discovery")
 		if err := t.ptr.refresh(); err != nil {