// Copyright 2011 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package net import ( "bufio" "context" "internal/poll" "internal/testenv" "io" "os" "runtime" "sync" "testing" "time" ) var prohibitionaryDialArgTests = []struct { network string address string }{ {"tcp6", "127.0.0.1"}, {"tcp6", "::ffff:127.0.0.1"}, } func TestProhibitionaryDialArg(t *testing.T) { testenv.MustHaveExternalNetwork(t) switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } if !supportsIPv4map() { t.Skip("mapping ipv4 address inside ipv6 address not supported") } ln, err := Listen("tcp", "[::]:0") if err != nil { t.Fatal(err) } defer ln.Close() _, port, err := SplitHostPort(ln.Addr().String()) if err != nil { t.Fatal(err) } for i, tt := range prohibitionaryDialArgTests { c, err := Dial(tt.network, JoinHostPort(tt.address, port)) if err == nil { c.Close() t.Errorf("#%d: %v", i, err) } } } func TestDialLocal(t *testing.T) { ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() _, port, err := SplitHostPort(ln.Addr().String()) if err != nil { t.Fatal(err) } c, err := Dial("tcp", JoinHostPort("", port)) if err != nil { t.Fatal(err) } c.Close() } func TestDialerDualStackFDLeak(t *testing.T) { switch runtime.GOOS { case "plan9": t.Skipf("%s does not have full support of socktest", runtime.GOOS) case "windows": t.Skipf("not implemented a way to cancel dial racers in TCP SYN-SENT state on %s", runtime.GOOS) case "openbsd": testenv.SkipFlaky(t, 15157) } if !supportsIPv4() || !supportsIPv6() { t.Skip("both IPv4 and IPv6 are required") } before := sw.Sockets() origTestHookLookupIP := testHookLookupIP defer func() { testHookLookupIP = origTestHookLookupIP }() testHookLookupIP = lookupLocalhost handler := func(dss *dualStackServer, ln Listener) { for { c, err := ln.Accept() if err != nil { return } c.Close() } } dss, err := newDualStackServer() if err != nil { t.Fatal(err) } if err := dss.buildup(handler); err != nil { dss.teardown() t.Fatal(err) } const N = 10 var wg sync.WaitGroup wg.Add(N) d := &Dialer{DualStack: true, Timeout: 5 * time.Second} for i := 0; i < N; i++ { go func() { defer wg.Done() c, err := d.Dial("tcp", JoinHostPort("localhost", dss.port)) if err != nil { t.Error(err) return } c.Close() }() } wg.Wait() dss.teardown() after := sw.Sockets() if len(after) != len(before) { t.Errorf("got %d; want %d", len(after), len(before)) } } // Define a pair of blackholed (IPv4, IPv6) addresses, for which dialTCP is // expected to hang until the timeout elapses. These addresses are reserved // for benchmarking by RFC 6890. const ( slowDst4 = "198.18.0.254" slowDst6 = "2001:2::254" ) // In some environments, the slow IPs may be explicitly unreachable, and fail // more quickly than expected. This test hook prevents dialTCP from returning // before the deadline. func slowDialTCP(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) { c, err := doDialTCP(ctx, net, laddr, raddr) if ParseIP(slowDst4).Equal(raddr.IP) || ParseIP(slowDst6).Equal(raddr.IP) { // Wait for the deadline, or indefinitely if none exists. <-ctx.Done() } return c, err } func dialClosedPort() (actual, expected time.Duration) { // Estimate the expected time for this platform. // On Windows, dialing a closed port takes roughly 1 second, // but other platforms should be instantaneous. if runtime.GOOS == "windows" { expected = 1500 * time.Millisecond } else if runtime.GOOS == "darwin" { expected = 150 * time.Millisecond } else { expected = 95 * time.Millisecond } l, err := Listen("tcp", "127.0.0.1:0") if err != nil { return 999 * time.Hour, expected } addr := l.Addr().String() l.Close() // On OpenBSD, interference from TestSelfConnect is mysteriously // causing the first attempt to hang for a few seconds, so we throw // away the first result and keep the second. for i := 1; ; i++ { startTime := time.Now() c, err := Dial("tcp", addr) if err == nil { c.Close() } elapsed := time.Now().Sub(startTime) if i == 2 { return elapsed, expected } } } func TestDialParallel(t *testing.T) { testenv.MustHaveExternalNetwork(t) if !supportsIPv4() || !supportsIPv6() { t.Skip("both IPv4 and IPv6 are required") } closedPortDelay, expectClosedPortDelay := dialClosedPort() if closedPortDelay > expectClosedPortDelay { t.Errorf("got %v; want <= %v", closedPortDelay, expectClosedPortDelay) } const instant time.Duration = 0 const fallbackDelay = 200 * time.Millisecond // Some cases will run quickly when "connection refused" is fast, // or trigger the fallbackDelay on Windows. This value holds the // lesser of the two delays. var closedPortOrFallbackDelay time.Duration if closedPortDelay < fallbackDelay { closedPortOrFallbackDelay = closedPortDelay } else { closedPortOrFallbackDelay = fallbackDelay } origTestHookDialTCP := testHookDialTCP defer func() { testHookDialTCP = origTestHookDialTCP }() testHookDialTCP = slowDialTCP nCopies := func(s string, n int) []string { out := make([]string, n) for i := 0; i < n; i++ { out[i] = s } return out } var testCases = []struct { primaries []string fallbacks []string teardownNetwork string expectOk bool expectElapsed time.Duration }{ // These should just work on the first try. {[]string{"127.0.0.1"}, []string{}, "", true, instant}, {[]string{"::1"}, []string{}, "", true, instant}, {[]string{"127.0.0.1", "::1"}, []string{slowDst6}, "tcp6", true, instant}, {[]string{"::1", "127.0.0.1"}, []string{slowDst4}, "tcp4", true, instant}, // Primary is slow; fallback should kick in. {[]string{slowDst4}, []string{"::1"}, "", true, fallbackDelay}, // Skip a "connection refused" in the primary thread. {[]string{"127.0.0.1", "::1"}, []string{}, "tcp4", true, closedPortDelay}, {[]string{"::1", "127.0.0.1"}, []string{}, "tcp6", true, closedPortDelay}, // Skip a "connection refused" in the fallback thread. {[]string{slowDst4, slowDst6}, []string{"::1", "127.0.0.1"}, "tcp6", true, fallbackDelay + closedPortDelay}, // Primary refused, fallback without delay. {[]string{"127.0.0.1"}, []string{"::1"}, "tcp4", true, closedPortOrFallbackDelay}, {[]string{"::1"}, []string{"127.0.0.1"}, "tcp6", true, closedPortOrFallbackDelay}, // Everything is refused. {[]string{"127.0.0.1"}, []string{}, "tcp4", false, closedPortDelay}, // Nothing to do; fail instantly. {[]string{}, []string{}, "", false, instant}, // Connecting to tons of addresses should not trip the deadline. {nCopies("::1", 1000), []string{}, "", true, instant}, } handler := func(dss *dualStackServer, ln Listener) { for { c, err := ln.Accept() if err != nil { return } c.Close() } } // Convert a list of IP strings into TCPAddrs. makeAddrs := func(ips []string, port string) addrList { var out addrList for _, ip := range ips { addr, err := ResolveTCPAddr("tcp", JoinHostPort(ip, port)) if err != nil { t.Fatal(err) } out = append(out, addr) } return out } for i, tt := range testCases { dss, err := newDualStackServer() if err != nil { t.Fatal(err) } defer dss.teardown() if err := dss.buildup(handler); err != nil { t.Fatal(err) } if tt.teardownNetwork != "" { // Destroy one of the listening sockets, creating an unreachable port. dss.teardownNetwork(tt.teardownNetwork) } primaries := makeAddrs(tt.primaries, dss.port) fallbacks := makeAddrs(tt.fallbacks, dss.port) d := Dialer{ FallbackDelay: fallbackDelay, } startTime := time.Now() dp := &dialParam{ Dialer: d, network: "tcp", address: "?", } c, err := dialParallel(context.Background(), dp, primaries, fallbacks) elapsed := time.Since(startTime) if c != nil { c.Close() } if tt.expectOk && err != nil { t.Errorf("#%d: got %v; want nil", i, err) } else if !tt.expectOk && err == nil { t.Errorf("#%d: got nil; want non-nil", i) } expectElapsedMin := tt.expectElapsed - 95*time.Millisecond expectElapsedMax := tt.expectElapsed + 95*time.Millisecond if !(elapsed >= expectElapsedMin) { t.Errorf("#%d: got %v; want >= %v", i, elapsed, expectElapsedMin) } else if !(elapsed <= expectElapsedMax) { t.Errorf("#%d: got %v; want <= %v", i, elapsed, expectElapsedMax) } // Repeat each case, ensuring that it can be canceled quickly. ctx, cancel := context.WithCancel(context.Background()) var wg sync.WaitGroup wg.Add(1) go func() { time.Sleep(5 * time.Millisecond) cancel() wg.Done() }() startTime = time.Now() c, err = dialParallel(ctx, dp, primaries, fallbacks) if c != nil { c.Close() } elapsed = time.Now().Sub(startTime) if elapsed > 100*time.Millisecond { t.Errorf("#%d (cancel): got %v; want <= 100ms", i, elapsed) } wg.Wait() } } func lookupSlowFast(ctx context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) { switch host { case "slow6loopback4": // Returns a slow IPv6 address, and a local IPv4 address. return []IPAddr{ {IP: ParseIP(slowDst6)}, {IP: ParseIP("127.0.0.1")}, }, nil default: return fn(ctx, host) } } func TestDialerFallbackDelay(t *testing.T) { testenv.MustHaveExternalNetwork(t) if !supportsIPv4() || !supportsIPv6() { t.Skip("both IPv4 and IPv6 are required") } origTestHookLookupIP := testHookLookupIP defer func() { testHookLookupIP = origTestHookLookupIP }() testHookLookupIP = lookupSlowFast origTestHookDialTCP := testHookDialTCP defer func() { testHookDialTCP = origTestHookDialTCP }() testHookDialTCP = slowDialTCP var testCases = []struct { dualstack bool delay time.Duration expectElapsed time.Duration }{ // Use a very brief delay, which should fallback immediately. {true, 1 * time.Nanosecond, 0}, // Use a 200ms explicit timeout. {true, 200 * time.Millisecond, 200 * time.Millisecond}, // The default is 300ms. {true, 0, 300 * time.Millisecond}, } handler := func(dss *dualStackServer, ln Listener) { for { c, err := ln.Accept() if err != nil { return } c.Close() } } dss, err := newDualStackServer() if err != nil { t.Fatal(err) } defer dss.teardown() if err := dss.buildup(handler); err != nil { t.Fatal(err) } for i, tt := range testCases { d := &Dialer{DualStack: tt.dualstack, FallbackDelay: tt.delay} startTime := time.Now() c, err := d.Dial("tcp", JoinHostPort("slow6loopback4", dss.port)) elapsed := time.Now().Sub(startTime) if err == nil { c.Close() } else if tt.dualstack { t.Error(err) } expectMin := tt.expectElapsed - 1*time.Millisecond expectMax := tt.expectElapsed + 95*time.Millisecond if !(elapsed >= expectMin) { t.Errorf("#%d: got %v; want >= %v", i, elapsed, expectMin) } if !(elapsed <= expectMax) { t.Errorf("#%d: got %v; want <= %v", i, elapsed, expectMax) } } } func TestDialParallelSpuriousConnection(t *testing.T) { if !supportsIPv4() || !supportsIPv6() { t.Skip("both IPv4 and IPv6 are required") } var wg sync.WaitGroup wg.Add(2) handler := func(dss *dualStackServer, ln Listener) { // Accept one connection per address. c, err := ln.Accept() if err != nil { t.Fatal(err) } // The client should close itself, without sending data. c.SetReadDeadline(time.Now().Add(1 * time.Second)) var b [1]byte if _, err := c.Read(b[:]); err != io.EOF { t.Errorf("got %v; want %v", err, io.EOF) } c.Close() wg.Done() } dss, err := newDualStackServer() if err != nil { t.Fatal(err) } defer dss.teardown() if err := dss.buildup(handler); err != nil { t.Fatal(err) } const fallbackDelay = 100 * time.Millisecond origTestHookDialTCP := testHookDialTCP defer func() { testHookDialTCP = origTestHookDialTCP }() testHookDialTCP = func(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) { // Sleep long enough for Happy Eyeballs to kick in, and inhibit cancelation. // This forces dialParallel to juggle two successful connections. time.Sleep(fallbackDelay * 2) // Now ignore the provided context (which will be canceled) and use a // different one to make sure this completes with a valid connection, // which we hope to be closed below: return doDialTCP(context.Background(), net, laddr, raddr) } d := Dialer{ FallbackDelay: fallbackDelay, } dp := &dialParam{ Dialer: d, network: "tcp", address: "?", } makeAddr := func(ip string) addrList { addr, err := ResolveTCPAddr("tcp", JoinHostPort(ip, dss.port)) if err != nil { t.Fatal(err) } return addrList{addr} } // dialParallel returns one connection (and closes the other.) c, err := dialParallel(context.Background(), dp, makeAddr("127.0.0.1"), makeAddr("::1")) if err != nil { t.Fatal(err) } c.Close() // The server should've seen both connections. wg.Wait() } func TestDialerPartialDeadline(t *testing.T) { now := time.Date(2000, time.January, 1, 0, 0, 0, 0, time.UTC) var testCases = []struct { now time.Time deadline time.Time addrs int expectDeadline time.Time expectErr error }{ // Regular division. {now, now.Add(12 * time.Second), 1, now.Add(12 * time.Second), nil}, {now, now.Add(12 * time.Second), 2, now.Add(6 * time.Second), nil}, {now, now.Add(12 * time.Second), 3, now.Add(4 * time.Second), nil}, // Bump against the 2-second sane minimum. {now, now.Add(12 * time.Second), 999, now.Add(2 * time.Second), nil}, // Total available is now below the sane minimum. {now, now.Add(1900 * time.Millisecond), 999, now.Add(1900 * time.Millisecond), nil}, // Null deadline. {now, noDeadline, 1, noDeadline, nil}, // Step the clock forward and cross the deadline. {now.Add(-1 * time.Millisecond), now, 1, now, nil}, {now.Add(0 * time.Millisecond), now, 1, noDeadline, poll.ErrTimeout}, {now.Add(1 * time.Millisecond), now, 1, noDeadline, poll.ErrTimeout}, } for i, tt := range testCases { deadline, err := partialDeadline(tt.now, tt.deadline, tt.addrs) if err != tt.expectErr { t.Errorf("#%d: got %v; want %v", i, err, tt.expectErr) } if !deadline.Equal(tt.expectDeadline) { t.Errorf("#%d: got %v; want %v", i, deadline, tt.expectDeadline) } } } func TestDialerLocalAddr(t *testing.T) { if !supportsIPv4() || !supportsIPv6() { t.Skip("both IPv4 and IPv6 are required") } type test struct { network, raddr string laddr Addr error } var tests = []test{ {"tcp4", "127.0.0.1", nil, nil}, {"tcp4", "127.0.0.1", &TCPAddr{}, nil}, {"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil}, {"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil}, {"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, &AddrError{Err: "some error"}}, {"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, nil}, {"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, nil}, {"tcp4", "127.0.0.1", &TCPAddr{IP: IPv6loopback}, errNoSuitableAddress}, {"tcp4", "127.0.0.1", &UDPAddr{}, &AddrError{Err: "some error"}}, {"tcp4", "127.0.0.1", &UnixAddr{}, &AddrError{Err: "some error"}}, {"tcp6", "::1", nil, nil}, {"tcp6", "::1", &TCPAddr{}, nil}, {"tcp6", "::1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil}, {"tcp6", "::1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil}, {"tcp6", "::1", &TCPAddr{IP: ParseIP("::")}, nil}, {"tcp6", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, errNoSuitableAddress}, {"tcp6", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, errNoSuitableAddress}, {"tcp6", "::1", &TCPAddr{IP: IPv6loopback}, nil}, {"tcp6", "::1", &UDPAddr{}, &AddrError{Err: "some error"}}, {"tcp6", "::1", &UnixAddr{}, &AddrError{Err: "some error"}}, {"tcp", "127.0.0.1", nil, nil}, {"tcp", "127.0.0.1", &TCPAddr{}, nil}, {"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil}, {"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil}, {"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, nil}, {"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, nil}, {"tcp", "127.0.0.1", &TCPAddr{IP: IPv6loopback}, errNoSuitableAddress}, {"tcp", "127.0.0.1", &UDPAddr{}, &AddrError{Err: "some error"}}, {"tcp", "127.0.0.1", &UnixAddr{}, &AddrError{Err: "some error"}}, {"tcp", "::1", nil, nil}, {"tcp", "::1", &TCPAddr{}, nil}, {"tcp", "::1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil}, {"tcp", "::1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil}, {"tcp", "::1", &TCPAddr{IP: ParseIP("::")}, nil}, {"tcp", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, errNoSuitableAddress}, {"tcp", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, errNoSuitableAddress}, {"tcp", "::1", &TCPAddr{IP: IPv6loopback}, nil}, {"tcp", "::1", &UDPAddr{}, &AddrError{Err: "some error"}}, {"tcp", "::1", &UnixAddr{}, &AddrError{Err: "some error"}}, } if supportsIPv4map() { tests = append(tests, test{ "tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, nil, }) } else { tests = append(tests, test{ "tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, &AddrError{Err: "some error"}, }) } origTestHookLookupIP := testHookLookupIP defer func() { testHookLookupIP = origTestHookLookupIP }() testHookLookupIP = lookupLocalhost handler := func(ls *localServer, ln Listener) { for { c, err := ln.Accept() if err != nil { return } c.Close() } } var err error var lss [2]*localServer for i, network := range []string{"tcp4", "tcp6"} { lss[i], err = newLocalServer(network) if err != nil { t.Fatal(err) } defer lss[i].teardown() if err := lss[i].buildup(handler); err != nil { t.Fatal(err) } } for _, tt := range tests { d := &Dialer{LocalAddr: tt.laddr} var addr string ip := ParseIP(tt.raddr) if ip.To4() != nil { addr = lss[0].Listener.Addr().String() } if ip.To16() != nil && ip.To4() == nil { addr = lss[1].Listener.Addr().String() } c, err := d.Dial(tt.network, addr) if err == nil && tt.error != nil || err != nil && tt.error == nil { // On Darwin this occasionally times out. // We don't know why. Issue #22019. if runtime.GOOS == "darwin" && tt.error == nil && os.IsTimeout(err) { t.Logf("ignoring timeout error on Darwin; see https://golang.org/issue/22019") } else { t.Errorf("%s %v->%s: got %v; want %v", tt.network, tt.laddr, tt.raddr, err, tt.error) } } if err != nil { if perr := parseDialError(err); perr != nil { t.Error(perr) } continue } c.Close() } } func TestDialerDualStack(t *testing.T) { testenv.SkipFlaky(t, 13324) if !supportsIPv4() || !supportsIPv6() { t.Skip("both IPv4 and IPv6 are required") } closedPortDelay, expectClosedPortDelay := dialClosedPort() if closedPortDelay > expectClosedPortDelay { t.Errorf("got %v; want <= %v", closedPortDelay, expectClosedPortDelay) } origTestHookLookupIP := testHookLookupIP defer func() { testHookLookupIP = origTestHookLookupIP }() testHookLookupIP = lookupLocalhost handler := func(dss *dualStackServer, ln Listener) { for { c, err := ln.Accept() if err != nil { return } c.Close() } } var timeout = 150*time.Millisecond + closedPortDelay for _, dualstack := range []bool{false, true} { dss, err := newDualStackServer() if err != nil { t.Fatal(err) } defer dss.teardown() if err := dss.buildup(handler); err != nil { t.Fatal(err) } d := &Dialer{DualStack: dualstack, Timeout: timeout} for range dss.lns { c, err := d.Dial("tcp", JoinHostPort("localhost", dss.port)) if err != nil { t.Error(err) continue } switch addr := c.LocalAddr().(*TCPAddr); { case addr.IP.To4() != nil: dss.teardownNetwork("tcp4") case addr.IP.To16() != nil && addr.IP.To4() == nil: dss.teardownNetwork("tcp6") } c.Close() } } } func TestDialerKeepAlive(t *testing.T) { handler := func(ls *localServer, ln Listener) { for { c, err := ln.Accept() if err != nil { return } c.Close() } } ls, err := newLocalServer("tcp") if err != nil { t.Fatal(err) } defer ls.teardown() if err := ls.buildup(handler); err != nil { t.Fatal(err) } defer func() { testHookSetKeepAlive = func() {} }() for _, keepAlive := range []bool{false, true} { got := false testHookSetKeepAlive = func() { got = true } var d Dialer if keepAlive { d.KeepAlive = 30 * time.Second } c, err := d.Dial("tcp", ls.Listener.Addr().String()) if err != nil { t.Fatal(err) } c.Close() if got != keepAlive { t.Errorf("Dialer.KeepAlive = %v: SetKeepAlive called = %v, want %v", d.KeepAlive, got, !got) } } } func TestDialCancel(t *testing.T) { switch testenv.Builder() { case "linux-arm64-buildlet": t.Skip("skipping on linux-arm64-buildlet; incompatible network config? issue 15191") case "": testenv.MustHaveExternalNetwork(t) } if runtime.GOOS == "nacl" { // nacl doesn't have external network access. t.Skipf("skipping on %s", runtime.GOOS) } blackholeIPPort := JoinHostPort(slowDst4, "1234") if !supportsIPv4() { blackholeIPPort = JoinHostPort(slowDst6, "1234") } ticker := time.NewTicker(10 * time.Millisecond) defer ticker.Stop() const cancelTick = 5 // the timer tick we cancel the dial at const timeoutTick = 100 var d Dialer cancel := make(chan struct{}) d.Cancel = cancel errc := make(chan error, 1) connc := make(chan Conn, 1) go func() { if c, err := d.Dial("tcp", blackholeIPPort); err != nil { errc <- err } else { connc <- c } }() ticks := 0 for { select { case <-ticker.C: ticks++ if ticks == cancelTick { close(cancel) } if ticks == timeoutTick { t.Fatal("timeout waiting for dial to fail") } case c := <-connc: c.Close() t.Fatal("unexpected successful connection") case err := <-errc: if perr := parseDialError(err); perr != nil { t.Error(perr) } if ticks < cancelTick { t.Fatalf("dial error after %d ticks (%d before cancel sent): %v", ticks, cancelTick-ticks, err) } if oe, ok := err.(*OpError); !ok || oe.Err != errCanceled { t.Fatalf("dial error = %v (%T); want OpError with Err == errCanceled", err, err) } return // success. } } } func TestCancelAfterDial(t *testing.T) { if testing.Short() { t.Skip("avoiding time.Sleep") } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } var wg sync.WaitGroup wg.Add(1) defer func() { ln.Close() wg.Wait() }() // Echo back the first line of each incoming connection. go func() { for { c, err := ln.Accept() if err != nil { break } rb := bufio.NewReader(c) line, err := rb.ReadString('\n') if err != nil { t.Error(err) c.Close() continue } if _, err := c.Write([]byte(line)); err != nil { t.Error(err) } c.Close() } wg.Done() }() try := func() { cancel := make(chan struct{}) d := &Dialer{Cancel: cancel} c, err := d.Dial("tcp", ln.Addr().String()) // Immediately after dialing, request cancelation and sleep. // Before Issue 15078 was fixed, this would cause subsequent operations // to fail with an i/o timeout roughly 50% of the time. close(cancel) time.Sleep(10 * time.Millisecond) if err != nil { t.Fatal(err) } defer c.Close() // Send some data to confirm that the connection is still alive. const message = "echo!\n" if _, err := c.Write([]byte(message)); err != nil { t.Fatal(err) } // The server should echo the line, and close the connection. rb := bufio.NewReader(c) line, err := rb.ReadString('\n') if err != nil { t.Fatal(err) } if line != message { t.Errorf("got %q; want %q", line, message) } if _, err := rb.ReadByte(); err != io.EOF { t.Errorf("got %v; want %v", err, io.EOF) } } // This bug manifested about 50% of the time, so try it a few times. for i := 0; i < 10; i++ { try() } } // Issue 18806: it should always be possible to net.Dial a // net.Listener().Addr().String when the listen address was ":n", even // if the machine has halfway configured IPv6 such that it can bind on // "::" not connect back to that same address. func TestDialListenerAddr(t *testing.T) { if testenv.Builder() == "" { testenv.MustHaveExternalNetwork(t) } ln, err := Listen("tcp", ":0") if err != nil { t.Fatal(err) } defer ln.Close() addr := ln.Addr().String() c, err := Dial("tcp", addr) if err != nil { t.Fatalf("for addr %q, dial error: %v", addr, err) } c.Close() }