test(quicnettest): assert rebind source change and upstream bind family

Extract upstreamBindAddr so each server address family is covered without host networking, and check that Rebind changes the upstream source address.

commit: 0d9258e879d992aa7439a6a45920b00316b1feb7
author: brice · 15d ago · 2026-10-07 07:01 UTC
parent: 767263f
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +36 -11

M internal/adapters/quicnettest/listen_test.go +18 -0


@@ -24,6 +24,7 @@ func TestExplicitListenSurvivesRebind(t *testing.T) {
24	24		client, err := net.ListenUDP("udp", &net.UDPAddr{IP: ip})
25	25		require.NoError(t, err)
26	26		defer client.Close()
	27	+	var sources []string
27	28		for attempt := 0; attempt < 2; attempt++ {
28	29		if attempt == 1 {
29	30		require.NoError(t, proxy.Rebind())

@@ -35,6 +36,7 @@ func TestExplicitListenSurvivesRebind(t *testing.T) {
35	36		n, from, err := server.ReadFromUDP(data)
36	37		require.NoError(t, err)
37	38		require.Equal(t, "fixture", string(data[:n]))
	39	+	sources = append(sources, from.String())
38	40		_, err = server.WriteToUDP(data[:n], from)
39	41		require.NoError(t, err)
40	42		require.NoError(t, client.SetReadDeadline(time.Now().Add(time.Second)))

@@ -42,6 +44,22 @@ func TestExplicitListenSurvivesRebind(t *testing.T) {
42	44		require.NoError(t, err)
43	45		require.Equal(t, "fixture", string(data[:n]))
44	46		}
	47	+	require.NotEqual(t, sources[0], sources[1], "rebind must change the upstream source address")
	48	+	})
	49	+	}
	50	+	}
	51	+
	52	+	func TestUpstreamBindAddrMatchesServerFamily(t *testing.T) {
	53	+	for _, tt := range []struct {
	54	+	server, want net.IP
	55	+	}{
	56	+	{net.IPv4(127, 0, 0, 1), net.IPv4(127, 0, 0, 1)},
	57	+	{net.IPv4(192, 0, 2, 7), net.IPv4zero},
	58	+	{net.IPv6loopback, net.IPv6loopback},
	59	+	{net.ParseIP("2001:db8::7"), net.IPv6unspecified},
	60	+	} {
	61	+	t.Run(tt.server.String(), func(t *testing.T) {
	62	+	require.True(t, upstreamBindAddr(tt.server).IP.Equal(tt.want))
45	63		})
46	64		}
47	65		}


@@ -24,6 +24,7 @@ func TestExplicitListenSurvivesRebind(t *testing.T) {
24	client, err := net.ListenUDP("udp", &net.UDPAddr{IP: ip})	24		client, err := net.ListenUDP("udp", &net.UDPAddr{IP: ip})
25	require.NoError(t, err)	25		require.NoError(t, err)
26	defer client.Close()	26		defer client.Close()
		27	+	var sources []string
27	for attempt := 0; attempt < 2; attempt++ {	28		for attempt := 0; attempt < 2; attempt++ {
28	if attempt == 1 {	29		if attempt == 1 {
29	require.NoError(t, proxy.Rebind())	30		require.NoError(t, proxy.Rebind())

@@ -35,6 +36,7 @@ func TestExplicitListenSurvivesRebind(t *testing.T) {
35	n, from, err := server.ReadFromUDP(data)	36		n, from, err := server.ReadFromUDP(data)
36	require.NoError(t, err)	37		require.NoError(t, err)
37	require.Equal(t, "fixture", string(data[:n]))	38		require.Equal(t, "fixture", string(data[:n]))
		39	+	sources = append(sources, from.String())
38	_, err = server.WriteToUDP(data[:n], from)	40		_, err = server.WriteToUDP(data[:n], from)
39	require.NoError(t, err)	41		require.NoError(t, err)
40	require.NoError(t, client.SetReadDeadline(time.Now().Add(time.Second)))	42		require.NoError(t, client.SetReadDeadline(time.Now().Add(time.Second)))

@@ -42,6 +44,22 @@ func TestExplicitListenSurvivesRebind(t *testing.T) {
42	require.NoError(t, err)	44		require.NoError(t, err)
43	require.Equal(t, "fixture", string(data[:n]))	45		require.Equal(t, "fixture", string(data[:n]))
44	}	46		}
		47	+	require.NotEqual(t, sources[0], sources[1], "rebind must change the upstream source address")
		48	+	})
		49	+	}
		50	+	}
		51	+
		52	+	func TestUpstreamBindAddrMatchesServerFamily(t *testing.T) {
		53	+	for _, tt := range []struct {
		54	+	server, want net.IP
		55	+	}{
		56	+	{net.IPv4(127, 0, 0, 1), net.IPv4(127, 0, 0, 1)},
		57	+	{net.IPv4(192, 0, 2, 7), net.IPv4zero},
		58	+	{net.IPv6loopback, net.IPv6loopback},
		59	+	{net.ParseIP("2001:db8::7"), net.IPv6unspecified},
		60	+	} {
		61	+	t.Run(tt.server.String(), func(t *testing.T) {
		62	+	require.True(t, upstreamBindAddr(tt.server).IP.Equal(tt.want))
45	})	63		})
46	}	64		}
47	}	65		}

M internal/adapters/quicnettest/proxy.go +18 -11


@@ -13,8 +13,24 @@ import (
13	13		// ErrClosed is returned by operations on a closed proxy.
14	14		var ErrClosed = errors.New("quicnettest: proxy is closed")
15	15
	16	+	// upstreamBindAddr returns the ephemeral upstream bind address in the server's
	17	+	// address family: loopback for a loopback server, unspecified otherwise.
	18	+	func upstreamBindAddr(server net.IP) *net.UDPAddr {
	19	+	switch {
	20	+	case server.To4() != nil && server.IsLoopback():
	21	+	return &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1)}
	22	+	case server.To4() != nil:
	23	+	return &net.UDPAddr{IP: net.IPv4zero}
	24	+	case server.IsLoopback():
	25	+	return &net.UDPAddr{IP: net.IPv6loopback}
	26	+	default:
	27	+	return &net.UDPAddr{IP: net.IPv6unspecified}
	28	+	}
	29	+	}
	30	+
16	31		// Proxy is a bounded, deterministic UDP relay with per-direction impairment. It
17		-	// listens on an ephemeral loopback port for clients and forwards to
	32	+	// listens on Config.ListenAddr (default: ephemeral IPv4 loopback) for clients
	33	+	// and forwards to
18	34		// Config.ServerAddr from a separate upstream socket that can be rebound to a
19	35		// new source address at any time.
20	36		type Proxy struct {

@@ -136,16 +152,7 @@ func New(cfg Config) (*Proxy, error) {
136	152		if err != nil {
137	153		return nil, fmt.Errorf("quicnettest: listen client socket: %w", err)
138	154		}
139		-	upstreamAddr := &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1)}
140		-	if !cfg.ServerAddr.IP.IsLoopback() {
141		-	upstreamAddr.IP = net.IPv4zero
142		-	}
143		-	if cfg.ServerAddr.IP.To4() == nil {
144		-	upstreamAddr.IP = net.IPv6unspecified
145		-	if cfg.ServerAddr.IP.IsLoopback() {
146		-	upstreamAddr.IP = net.IPv6loopback
147		-	}
148		-	}
	155	+	upstreamAddr := upstreamBindAddr(cfg.ServerAddr.IP)
149	156		upstream, err := net.ListenUDP("udp", upstreamAddr)
150	157		if err != nil {
151	158		_ = clientConn.Close()

 // ErrClosed is returned by operations on a closed proxy.
 var ErrClosed = errors.New("quicnettest: proxy is closed")
+// upstreamBindAddr returns the ephemeral upstream bind address in the server's
+// address family: loopback for a loopback server, unspecified otherwise.
+func upstreamBindAddr(server net.IP) *net.UDPAddr {
+	switch {
+	case server.To4() != nil && server.IsLoopback():
+		return &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1)}
+	case server.To4() != nil:
+		return &net.UDPAddr{IP: net.IPv4zero}
+	case server.IsLoopback():
+		return &net.UDPAddr{IP: net.IPv6loopback}
+	default:
+		return &net.UDPAddr{IP: net.IPv6unspecified}
+	}
+}
 // Proxy is a bounded, deterministic UDP relay with per-direction impairment. It
-// listens on an ephemeral loopback port for clients and forwards to
+// listens on Config.ListenAddr (default: ephemeral IPv4 loopback) for clients
+// and forwards to
 // Config.ServerAddr from a separate upstream socket that can be rebound to a
 // new source address at any time.
 type Proxy struct {
 	if err != nil {
 		return nil, fmt.Errorf("quicnettest: listen client socket: %w", err)
 	}
-	upstreamAddr := &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1)}
+	upstreamAddr := upstreamBindAddr(cfg.ServerAddr.IP)
-	if !cfg.ServerAddr.IP.IsLoopback() {
-		upstreamAddr.IP = net.IPv4zero
-	}
-	if cfg.ServerAddr.IP.To4() == nil {
-		upstreamAddr.IP = net.IPv6unspecified
-		if cfg.ServerAddr.IP.IsLoopback() {
-			upstreamAddr.IP = net.IPv6loopback
-		}
-	}
 	upstream, err := net.ListenUDP("udp", upstreamAddr)
 	if err != nil {
 		_ = clientConn.Close()