Pull request 2750: AGDNS-3720-imp-cert-has-ip

Squashed commit of the following:

commit fb4eef0
Merge: 4d3772f e0b474f
Author: Maksim Kazantsev <m.kazantsev@adguard.com>
Date:   Thu Aug 13 17:50:58 2026 +0300

    Merge branch 'master' into AGDNS-3720-imp-cert-has-ip

commit 4d3772f
Author: Maksim Kazantsev <m.kazantsev@adguard.com>
Date:   Thu Aug 13 17:28:29 2026 +0300

    home: imp tests;

commit 7f2d3fe
Author: Maksim Kazantsev <m.kazantsev@adguard.com>
Date:   Thu Aug 13 11:55:48 2026 +0300

    home: fix test;

commit a1459d0
Author: Maksim Kazantsev <m.kazantsev@adguard.com>
Date:   Thu Aug 13 11:29:57 2026 +0300

    home: imp test;

commit c24fadd
Author: Maksim Kazantsev <m.kazantsev@adguard.com>
Date:   Wed Aug 12 15:17:04 2026 +0300

    dnsforward: imp code;

commit d9ad570
Author: Maksim Kazantsev <m.kazantsev@adguard.com>
Date:   Wed Aug 12 15:14:23 2026 +0300

    home: cover has ip addrs with tests; rm invalid todo;

Author: makazantsev

internal/dnsforward/process.go

@@ -251,28 +251,29 @@ func (s *Server) makeDDRResponse(req *dns.Msg) (resp *dns.Msg) {
 // server's TLS certificate contains IP addresses.  req and resp must not be
 // nil.
 func (s *Server) appendDoTResolvers(req, resp *dns.Msg, domainName string) {
-	hasIPAddrs := s.tlsConfigProvider.HasIPAddrs()
-
-	if hasIPAddrs {
-		// Only add DNS-over-TLS resolvers in case the certificate contains IP
-		// addresses.
-		//
-		// See https://github.com/AdguardTeam/AdGuardHome/issues/4927.
-		for _, addr := range s.dnsProxy.TLSListenAddr {
-			values := []dns.SVCBKeyValue{
-				&dns.SVCBAlpn{Alpn: []string{"dot"}},
-				&dns.SVCBPort{Port: uint16(addr.Port)},
-			}
+	if !s.tlsConfigProvider.HasIPAddrs() {
+		return
+	}
 
-			ans := &dns.SVCB{
-				Hdr:      s.hdr(req, dns.TypeSVCB),
-				Priority: 1,
-				Target:   domainName,
-				Value:    values,
-			}
+	// Only add DNS-over-TLS resolvers in case the certificate contains IP
+	// addresses.
+	//
+	// See https://github.com/AdguardTeam/AdGuardHome/issues/4927.
+	for _, addr := range s.dnsProxy.TLSListenAddr {
+		values := []dns.SVCBKeyValue{
+			&dns.SVCBAlpn{Alpn: []string{"dot"}},
+			&dns.SVCBPort{Port: uint16(addr.Port)},
+		}
 
-			resp.Answer = append(resp.Answer, ans)
+		ans := &dns.SVCB{
+			Hdr:      s.hdr(req, dns.TypeSVCB),
+			Priority: 1,
+			Target:   domainName,
+			Value:    values,
 		}
+
+		resp.Answer = append(resp.Answer, ans)
+
 	}
 }
 

internal/home/tls.go

@@ -916,8 +916,6 @@ func (m *tlsManager) HasIPAddrs() (ok bool) {
 		return false
 	}
 
-	// TODO(m.kazantsev):  Consider storing the value instead of parsing each
-	// time.
 	return aghtls.CertificateHasIP(m.tlsCert.Leaf)
 }
 

internal/home/tls_internal_test.go

@@ -8,6 +8,7 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"math/big"
+	"net"
 	"os"
 	"path/filepath"
 	"testing"
@@ -200,6 +201,35 @@ func newCertWithoutIP(tb testing.TB) (
 	return caCert, buf.Bytes(), leafKeyPEM
 }
 
+// newCertWithIP generates a self-signed certificate with an IP address in its
+// SAN extension and returns the PEM-encoded certificate and private key.
+func newCertWithIP(tb testing.TB) (certPEM, keyPEM []byte) {
+	tb.Helper()
+
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	require.NoError(tb, err)
+
+	now := time.Now()
+	tmpl := &x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		NotBefore:    now.Add(-time.Hour),
+		NotAfter:     now.Add(time.Hour),
+		KeyUsage:     x509.KeyUsageDigitalSignature,
+		IPAddresses:  []net.IP{net.ParseIP("192.0.2.1")},
+	}
+
+	certDER, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &key.PublicKey, key)
+	require.NoError(tb, err)
+
+	certPEM = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER})
+	keyPEM = pem.EncodeToMemory(&pem.Block{
+		Type:  "RSA PRIVATE KEY",
+		Bytes: x509.MarshalPKCS1PrivateKey(key),
+	})
+
+	return certPEM, keyPEM
+}
+
 // newCertAndKey is a helper function that generates certificate and key.
 func newCertAndKey(tb testing.TB, n int64) (certDER []byte, key *rsa.PrivateKey) {
 	tb.Helper()
@@ -348,3 +378,85 @@ func TestTLSManager_Reload(t *testing.T) {
 	extTLSConf = m.ExtendedTLSConfig()
 	assertCertSerialNumber(t, extTLSConf, snAfter)
 }
+
+func TestTLSManager_HasIPAddrs(t *testing.T) {
+	t.Parallel()
+
+	_, noIPChainPEM, noIPKeyPEM := newCertWithoutIP(t)
+	ipChainPEM, ipKeyPEM := newCertWithIP(t)
+
+	noIPSettings := &aghtls.ExtendedTLSConfig{
+		Enabled:          true,
+		CertificateChain: string(noIPChainPEM),
+		PrivateKey:       string(noIPKeyPEM),
+	}
+	ipSettings := &aghtls.ExtendedTLSConfig{
+		Enabled:          true,
+		CertificateChain: string(ipChainPEM),
+		PrivateKey:       string(ipKeyPEM),
+	}
+
+	testCases := []struct {
+		want                 assert.BoolAssertionFunc
+		name                 string
+		certificateChainData []byte
+		privateKeyData       []byte
+		settings             *aghtls.ExtendedTLSConfig
+	}{{
+		name:     "no_ip_in_cert",
+		settings: noIPSettings,
+		want:     assert.False,
+	}, {
+		name:     "has_ip_in_cert",
+		settings: ipSettings,
+		want:     assert.True,
+	}, {
+		name:                 "updated_to_ip",
+		settings:             noIPSettings,
+		certificateChainData: ipChainPEM,
+		privateKeyData:       ipKeyPEM,
+		want:                 assert.True,
+	}, {
+		name:                 "updated_to_no_ip",
+		settings:             ipSettings,
+		certificateChainData: noIPChainPEM,
+		privateKeyData:       noIPKeyPEM,
+		want:                 assert.False,
+	}}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Do not run in parallel because the test modifies the TLS
+			// manager's state.
+			ctx := testutil.ContextWithTimeout(t, testTimeout)
+
+			m, err := newTLSManager(ctx, &tlsManagerConfig{
+				logger:        testLogger,
+				confModifier:  agh.EmptyConfigModifier{},
+				manager:       aghtls.EmptyManager{},
+				extTLSConf:    tc.settings,
+				servePlainDNS: false,
+			})
+			require.NoError(t, err)
+
+			if tc.certificateChainData == nil && tc.privateKeyData == nil {
+				tc.want(t, m.HasIPAddrs())
+
+				return
+			}
+
+			func() {
+				m.mu.Lock()
+				defer m.mu.Unlock()
+
+				var cert tls.Certificate
+				cert, err = tls.X509KeyPair(tc.certificateChainData, tc.privateKeyData)
+				require.NoError(t, err)
+
+				m.tlsCert = &cert
+			}()
+
+			tc.want(t, m.HasIPAddrs())
+		})
+	}
+}