net: add sequential and RFC 6555-compliant TCP dialing.
dialSerial connects to a list of addresses in sequence. If a
timeout is specified, then each address gets an equal fraction of the
remaining time, with a magic constant (2 seconds) to prevent
"dial a million addresses" from allotting zero time to each.
Normally, net.Dial passes the DNS stub resolver's output to dialSerial.
If an error occurs (like destination/port unreachable), it quickly skips
to the next address, but a blackhole in the network will cause the
connection to hang until the timeout elapses. This is how UNIXy clients
traditionally behave, and is usually sufficient for non-broken networks.
The DualStack flag enables dialParallel, which implements Happy Eyeballs
by racing two dialSerial goroutines, giving the preferred family a
head start (300ms by default). This allows clients to avoid long
timeouts when the network blackholes IPv4 xor IPv6.
Fixes #8453
Fixes #8455
Fixes #8847
Change-Id: Ie415809c9226a1f7342b0217dcdd8f224ae19058
Reviewed-on: https://go-review.googlesource.com/8768
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/net/dial.go b/src/net/dial.go
index 4f0c6cb..4b430de 100644
--- a/src/net/dial.go
+++ b/src/net/dial.go
@@ -21,6 +21,9 @@
//
// The default is no timeout.
//
+ // When dialing a name with multiple IP addresses, the timeout
+ // may be divided between them.
+ //
// With or without a timeout, the operating system may impose
// its own earlier timeout. For instance, TCP timeouts are
// often around 3 minutes.
@@ -38,13 +41,17 @@
// If nil, a local address is automatically chosen.
LocalAddr Addr
- // DualStack allows a single dial to attempt to establish
- // multiple IPv4 and IPv6 connections and to return the first
- // established connection when the network is "tcp" and the
- // destination is a host name that has multiple address family
- // DNS records.
+ // DualStack enables RFC 6555-compliant "Happy Eyeballs" dialing
+ // when the network is "tcp" and the destination is a host name
+ // with both IPv4 and IPv6 addresses. This allows a client to
+ // tolerate networks where one address family is silently broken.
DualStack bool
+ // FallbackDelay specifies the length of time to wait before
+ // spawning a fallback connection, when DualStack is enabled.
+ // If zero, a default delay of 300ms is used.
+ FallbackDelay time.Duration
+
// KeepAlive specifies the keep-alive period for an active
// network connection.
// If zero, keep-alives are not enabled. Network protocols
@@ -54,11 +61,11 @@
// Return either now+Timeout or Deadline, whichever comes first.
// Or zero, if neither is set.
-func (d *Dialer) deadline() time.Time {
+func (d *Dialer) deadline(now time.Time) time.Time {
if d.Timeout == 0 {
return d.Deadline
}
- timeoutDeadline := time.Now().Add(d.Timeout)
+ timeoutDeadline := now.Add(d.Timeout)
if d.Deadline.IsZero() || timeoutDeadline.Before(d.Deadline) {
return timeoutDeadline
} else {
@@ -66,6 +73,39 @@
}
}
+// partialDeadline returns the deadline to use for a single address,
+// when multiple addresses are pending.
+func (d *Dialer) partialDeadline(now time.Time, addrsRemaining int) (time.Time, error) {
+ deadline := d.deadline(now)
+ if deadline.IsZero() {
+ return deadline, nil
+ }
+ timeRemaining := deadline.Sub(now)
+ if timeRemaining <= 0 {
+ return time.Time{}, errTimeout
+ }
+ // Tentatively allocate equal time to each remaining address.
+ timeout := timeRemaining / time.Duration(addrsRemaining)
+ // If the time per address is too short, steal from the end of the list.
+ const saneMinimum = 2 * time.Second
+ if timeout < saneMinimum {
+ if timeRemaining < saneMinimum {
+ timeout = timeRemaining
+ } else {
+ timeout = saneMinimum
+ }
+ }
+ return now.Add(timeout), nil
+}
+
+func (d *Dialer) fallbackDelay() time.Duration {
+ if d.FallbackDelay > 0 {
+ return d.FallbackDelay
+ } else {
+ return 300 * time.Millisecond
+ }
+}
+
func parseNetwork(net string) (afnet string, proto int, err error) {
i := last(net, ':')
if i < 0 { // no colon
@@ -154,30 +194,44 @@
return d.Dial(network, address)
}
+// dialContext holds common state for all dial operations.
+type dialContext struct {
+ Dialer
+ network, address string
+}
+
// Dial connects to the address on the named network.
//
// See func Dial for a description of the network and address
// parameters.
func (d *Dialer) Dial(network, address string) (Conn, error) {
- addrs, err := resolveAddrList("dial", network, address, d.deadline())
+ addrs, err := resolveAddrList("dial", network, address, d.deadline(time.Now()))
if err != nil {
return nil, &OpError{Op: "dial", Net: network, Source: nil, Addr: nil, Err: err}
}
- var dialer func(deadline time.Time) (Conn, error)
+
+ ctx := &dialContext{
+ Dialer: *d,
+ network: network,
+ address: address,
+ }
+
+ var primaries, fallbacks addrList
if d.DualStack && network == "tcp" {
- primaries, fallbacks := addrs.partition(isIPv4)
- if len(fallbacks) > 0 {
- dialer = func(deadline time.Time) (Conn, error) {
- return dialMulti(network, address, d.LocalAddr, addrList{primaries[0], fallbacks[0]}, deadline)
- }
- }
+ primaries, fallbacks = addrs.partition(isIPv4)
+ } else {
+ primaries = addrs
}
- if dialer == nil {
- dialer = func(deadline time.Time) (Conn, error) {
- return dialSingle(network, address, d.LocalAddr, addrs.first(isIPv4), deadline)
- }
+
+ var c Conn
+ if len(fallbacks) == 0 {
+ // dialParallel can accept an empty fallbacks list,
+ // but this shortcut avoids the goroutine/channel overhead.
+ c, err = dialSerial(ctx, primaries, nil)
+ } else {
+ c, err = dialParallel(ctx, primaries, fallbacks)
}
- c, err := dial(network, addrs.first(isIPv4), dialer, d.deadline())
+
if d.KeepAlive > 0 && err == nil {
if tc, ok := c.(*TCPConn); ok {
setKeepAlive(tc.fd, true)
@@ -188,70 +242,135 @@
return c, err
}
-// dialMulti attempts to establish connections to each destination of
-// the list of addresses. It will return the first established
-// connection and close the other connections. Otherwise it returns
-// error on the last attempt.
-func dialMulti(net, addr string, la Addr, ras addrList, deadline time.Time) (Conn, error) {
- type racer struct {
- Conn
- error
- }
- // Sig controls the flow of dial results on lane. It passes a
- // token to the next racer and also indicates the end of flow
- // by using closed channel.
- sig := make(chan bool, 1)
- lane := make(chan racer, 1)
- for _, ra := range ras {
- go func(ra Addr) {
- c, err := dialSingle(net, addr, la, ra, deadline)
- if _, ok := <-sig; ok {
- lane <- racer{c, err}
- } else if err == nil {
- // We have to return the resources
- // that belong to the other
- // connections here for avoiding
- // unnecessary resource starvation.
- c.Close()
- }
- }(ra)
- }
- defer close(sig)
- lastErr := errTimeout
- nracers := len(ras)
- for nracers > 0 {
- sig <- true
- racer := <-lane
- if racer.error == nil {
- return racer.Conn, nil
+// dialParallel races two copies of dialSerial, giving the first a
+// head start. It returns the first established connection and
+// closes the others. Otherwise it returns an error from the first
+// primary address.
+func dialParallel(ctx *dialContext, primaries, fallbacks addrList) (Conn, error) {
+ results := make(chan dialResult) // unbuffered, so dialSerialAsync can detect race loss & cleanup
+ cancel := make(chan struct{})
+ defer close(cancel)
+
+ // Spawn the primary racer.
+ go dialSerialAsync(ctx, primaries, nil, cancel, results)
+
+ // Spawn the fallback racer.
+ fallbackTimer := time.NewTimer(ctx.fallbackDelay())
+ go dialSerialAsync(ctx, fallbacks, fallbackTimer, cancel, results)
+
+ var primaryErr error
+ for nracers := 2; nracers > 0; nracers-- {
+ res := <-results
+ // If we're still waiting for a connection, then hasten the delay.
+ // Otherwise, disable the Timer and let cancel take over.
+ if fallbackTimer.Stop() && res.error != nil {
+ fallbackTimer.Reset(0)
}
- lastErr = racer.error
- nracers--
+ if res.error == nil {
+ return res.Conn, nil
+ }
+ if res.primary {
+ primaryErr = res.error
+ }
}
- return nil, lastErr
+ return nil, primaryErr
+}
+
+type dialResult struct {
+ Conn
+ error
+ primary bool
+}
+
+// dialSerialAsync runs dialSerial after some delay, and returns the
+// resulting connection through a channel. When racing two connections,
+// the primary goroutine uses a nil timer to omit the delay.
+func dialSerialAsync(ctx *dialContext, ras addrList, timer *time.Timer, cancel <-chan struct{}, results chan<- dialResult) {
+ if timer != nil {
+ // We're in the fallback goroutine; sleep before connecting.
+ select {
+ case <-timer.C:
+ case <-cancel:
+ return
+ }
+ }
+ c, err := dialSerial(ctx, ras, cancel)
+ select {
+ case results <- dialResult{c, err, timer == nil}:
+ // We won the race.
+ case <-cancel:
+ // The other goroutine won the race.
+ if c != nil {
+ c.Close()
+ }
+ }
+}
+
+// dialSerial connects to a list of addresses in sequence, returning
+// either the first successful connection, or the first error.
+func dialSerial(ctx *dialContext, ras addrList, cancel <-chan struct{}) (Conn, error) {
+ var firstErr error // The error from the first address is most relevant.
+
+ for i, ra := range ras {
+ select {
+ case <-cancel:
+ return nil, &OpError{Op: "dial", Net: ctx.network, Source: ctx.LocalAddr, Addr: ra, Err: errCanceled}
+ default:
+ }
+
+ partialDeadline, err := ctx.partialDeadline(time.Now(), len(ras)-i)
+ if err != nil {
+ // Ran out of time.
+ if firstErr == nil {
+ firstErr = &OpError{Op: "dial", Net: ctx.network, Source: ctx.LocalAddr, Addr: ra, Err: err}
+ }
+ break
+ }
+
+ // dialTCP does not support cancelation (see golang.org/issue/11225),
+ // so if cancel fires, we'll continue trying to connect until the next
+ // timeout, or return a spurious connection for the caller to close.
+ dialer := func(d time.Time) (Conn, error) {
+ return dialSingle(ctx, ra, d)
+ }
+ c, err := dial(ctx.network, ra, dialer, partialDeadline)
+ if err == nil {
+ return c, nil
+ }
+ if firstErr == nil {
+ firstErr = err
+ }
+ }
+
+ if firstErr == nil {
+ firstErr = &OpError{Op: "dial", Net: ctx.network, Source: nil, Addr: nil, Err: errMissingAddress}
+ }
+ return nil, firstErr
}
// dialSingle attempts to establish and returns a single connection to
-// the destination address.
-func dialSingle(net, addr string, la, ra Addr, deadline time.Time) (c Conn, err error) {
+// the destination address. This must be called through the OS-specific
+// dial function, because some OSes don't implement the deadline feature.
+func dialSingle(ctx *dialContext, ra Addr, deadline time.Time) (c Conn, err error) {
+ la := ctx.LocalAddr
if la != nil && la.Network() != ra.Network() {
- return nil, &OpError{Op: "dial", Net: net, Source: la, Addr: ra, Err: errors.New("mismatched local address type " + la.Network())}
+ return nil, &OpError{Op: "dial", Net: ctx.network, Source: la, Addr: ra, Err: errors.New("mismatched local address type " + la.Network())}
}
switch ra := ra.(type) {
case *TCPAddr:
la, _ := la.(*TCPAddr)
- c, err = dialTCP(net, la, ra, deadline)
+ c, err = testHookDialTCP(ctx.network, la, ra, deadline)
case *UDPAddr:
la, _ := la.(*UDPAddr)
- c, err = dialUDP(net, la, ra, deadline)
+ c, err = dialUDP(ctx.network, la, ra, deadline)
case *IPAddr:
la, _ := la.(*IPAddr)
- c, err = dialIP(net, la, ra, deadline)
+ c, err = dialIP(ctx.network, la, ra, deadline)
case *UnixAddr:
la, _ := la.(*UnixAddr)
- c, err = dialUnix(net, la, ra, deadline)
+ c, err = dialUnix(ctx.network, la, ra, deadline)
default:
- return nil, &OpError{Op: "dial", Net: net, Source: la, Addr: ra, Err: &AddrError{Err: "unexpected address type", Addr: addr}}
+ return nil, &OpError{Op: "dial", Net: ctx.network, Source: la, Addr: ra, Err: &AddrError{Err: "unexpected address type", Addr: ctx.address}}
}
if err != nil {
return nil, err // c is non-nil interface containing nil pointer
diff --git a/src/net/dial_test.go b/src/net/dial_test.go
index f5141bc..9848f30 100644
--- a/src/net/dial_test.go
+++ b/src/net/dial_test.go
@@ -5,6 +5,7 @@
package net
import (
+ "io"
"net/internal/socktest"
"runtime"
"sync"
@@ -207,6 +208,360 @@
}
}
+// 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 = "192.18.0.254"
+ slowDst6 = "2001:2::254"
+ slowTimeout = 1 * time.Second
+)
+
+// 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(net string, laddr, raddr *TCPAddr, deadline time.Time) (*TCPConn, error) {
+ c, err := dialTCP(net, laddr, raddr, deadline)
+ if ParseIP(slowDst4).Equal(raddr.IP) || ParseIP(slowDst6).Equal(raddr.IP) {
+ time.Sleep(deadline.Sub(time.Now()))
+ }
+ return c, err
+}
+
+func dialClosedPort() time.Duration {
+ l, err := Listen("tcp", "127.0.0.1:0")
+ if err != nil {
+ return 999 * time.Hour
+ }
+ 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
+ }
+ }
+}
+
+func TestDialParallel(t *testing.T) {
+ if testing.Short() || !*testExternal {
+ t.Skip("avoid external network")
+ }
+ if !supportsIPv4 || !supportsIPv6 {
+ t.Skip("both IPv4 and IPv6 are required")
+ }
+
+ // Determine the time required to dial a closed port.
+ // On Windows, this takes roughly 1 second, but other platforms
+ // are expected to be instantaneous.
+ closedPortDelay := dialClosedPort()
+ var expectClosedPortDelay time.Duration
+ if runtime.GOOS == "windows" {
+ expectClosedPortDelay = 1095 * time.Millisecond
+ } else {
+ expectClosedPortDelay = 95 * time.Millisecond
+ }
+ 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([]streamListener{
+ {network: "tcp4", address: "127.0.0.1"},
+ {network: "tcp6", address: "::1"},
+ })
+ 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)
+ ctx := &dialContext{
+ Dialer: Dialer{
+ FallbackDelay: fallbackDelay,
+ Timeout: slowTimeout,
+ },
+ network: "tcp",
+ address: "?",
+ }
+ startTime := time.Now()
+ c, err := dialParallel(ctx, primaries, fallbacks)
+ elapsed := time.Now().Sub(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)
+ }
+ }
+ // Wait for any slowDst4/slowDst6 connections to timeout.
+ time.Sleep(slowTimeout * 3 / 2)
+}
+
+func lookupSlowFast(fn func(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(host)
+ }
+}
+
+func TestDialerFallbackDelay(t *testing.T) {
+ if testing.Short() || !*testExternal {
+ t.Skip("avoid external network")
+ }
+ 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},
+ // This case is last, in order to wait for hanging slowDst6 connections.
+ {false, 0, slowTimeout},
+ }
+
+ handler := func(dss *dualStackServer, ln Listener) {
+ for {
+ c, err := ln.Accept()
+ if err != nil {
+ return
+ }
+ c.Close()
+ }
+ }
+ dss, err := newDualStackServer([]streamListener{
+ {network: "tcp", address: "127.0.0.1"},
+ })
+ 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, Timeout: slowTimeout}
+
+ 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 TestDialSerialAsyncSpuriousConnection(t *testing.T) {
+ ln, err := newLocalListener("tcp")
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer ln.Close()
+
+ ctx := &dialContext{
+ network: "tcp",
+ address: "?",
+ }
+
+ results := make(chan dialResult)
+ cancel := make(chan struct{})
+
+ // Spawn a connection in the background.
+ go dialSerialAsync(ctx, addrList{ln.Addr()}, nil, cancel, results)
+
+ // Receive it at the server.
+ c, err := ln.Accept()
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer c.Close()
+
+ // Tell dialSerialAsync that someone else won the race.
+ close(cancel)
+
+ // The connection 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)
+ }
+}
+
+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, errTimeout},
+ {now.Add(1 * time.Millisecond), now, 1, noDeadline, errTimeout},
+ }
+ for i, tt := range testCases {
+ d := Dialer{Deadline: tt.deadline}
+ deadline, err := d.partialDeadline(tt.now, tt.addrs)
+ if err != tt.expectErr {
+ t.Errorf("#%d: got %v; want %v", i, err, tt.expectErr)
+ }
+ if deadline != tt.expectDeadline {
+ t.Errorf("#%d: got %v; want %v", i, deadline, tt.expectDeadline)
+ }
+ }
+}
+
func TestDialerLocalAddr(t *testing.T) {
ch := make(chan error, 1)
handler := func(ls *localServer, ln Listener) {
@@ -262,33 +617,36 @@
c.Close()
}
}
- dss, err := newDualStackServer([]streamListener{
- {network: "tcp4", address: "127.0.0.1"},
- {network: "tcp6", address: "::1"},
- })
- if err != nil {
- t.Fatal(err)
- }
- defer dss.teardown()
- if err := dss.buildup(handler); err != nil {
- t.Fatal(err)
- }
const T = 100 * time.Millisecond
- d := &Dialer{DualStack: true, Timeout: T}
- for range dss.lns {
- c, err := d.Dial("tcp", JoinHostPort("localhost", dss.port))
+ for _, dualstack := range []bool{false, true} {
+ dss, err := newDualStackServer([]streamListener{
+ {network: "tcp4", address: "127.0.0.1"},
+ {network: "tcp6", address: "::1"},
+ })
if err != nil {
- t.Error(err)
- continue
+ t.Fatal(err)
}
- 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")
+ defer dss.teardown()
+ if err := dss.buildup(handler); err != nil {
+ t.Fatal(err)
}
- c.Close()
+
+ d := &Dialer{DualStack: dualstack, Timeout: T}
+ 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()
+ }
}
time.Sleep(2 * T) // wait for the dial racers to stop
}
diff --git a/src/net/hook.go b/src/net/hook.go
index f8de28b..9ab34c0 100644
--- a/src/net/hook.go
+++ b/src/net/hook.go
@@ -5,6 +5,7 @@
package net
var (
+ testHookDialTCP = dialTCP
testHookHostsPath = "/etc/hosts"
testHookLookupIP = func(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) { return fn(host) }
testHookSetKeepAlive = func() {}
diff --git a/src/net/net.go b/src/net/net.go
index fbeac81..cd1372f 100644
--- a/src/net/net.go
+++ b/src/net/net.go
@@ -321,6 +321,7 @@
// For both read and write operations.
errTimeout error = &timeoutError{}
+ errCanceled = errors.New("operation was canceled")
errClosing = errors.New("use of closed network connection")
ErrWriteToConnected = errors.New("use of WriteTo with pre-connected connection")
)
