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net: wait for cancelation goroutine before returning from connect.
This fixes a race which made it possible to cancel a connection after returning from net.Dial. Fixes #15035 Fixes #15078 Change-Id: Iec6215009538362f7ad9f408a33549f3e94d1606 Reviewed-on: https://go-review.googlesource.com/21497 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
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parent
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@ -5,6 +5,7 @@
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package net
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import (
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"bufio"
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"internal/testenv"
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"io"
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"net/internal/socktest"
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@ -871,3 +872,84 @@ func TestDialCancel(t *testing.T) {
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}
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}
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}
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func TestCancelAfterDial(t *testing.T) {
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if testing.Short() {
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t.Skip("avoiding time.Sleep")
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}
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ln, err := newLocalListener("tcp")
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if err != nil {
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t.Fatal(err)
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}
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var wg sync.WaitGroup
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wg.Add(1)
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defer func() {
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ln.Close()
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wg.Wait()
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}()
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// Echo back the first line of each incoming connection.
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go func() {
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for {
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c, err := ln.Accept()
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if err != nil {
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break
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}
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rb := bufio.NewReader(c)
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line, err := rb.ReadString('\n')
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if err != nil {
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t.Error(err)
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c.Close()
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continue
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}
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if _, err := c.Write([]byte(line)); err != nil {
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t.Error(err)
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}
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c.Close()
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}
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wg.Done()
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}()
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try := func() {
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cancel := make(chan struct{})
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d := &Dialer{Cancel: cancel}
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c, err := d.Dial("tcp", ln.Addr().String())
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// Immediately after dialing, request cancelation and sleep.
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// Before Issue 15078 was fixed, this would cause subsequent operations
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// to fail with an i/o timeout roughly 50% of the time.
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close(cancel)
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time.Sleep(10 * time.Millisecond)
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if err != nil {
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t.Fatal(err)
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}
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defer c.Close()
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// Send some data to confirm that the connection is still alive.
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const message = "echo!\n"
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if _, err := c.Write([]byte(message)); err != nil {
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t.Fatal(err)
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}
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// The server should echo the line, and close the connection.
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rb := bufio.NewReader(c)
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line, err := rb.ReadString('\n')
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if err != nil {
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t.Fatal(err)
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}
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if line != message {
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t.Errorf("got %q; want %q", line, message)
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}
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if _, err := rb.ReadByte(); err != io.EOF {
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t.Errorf("got %v; want %v", err, io.EOF)
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}
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}
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// This bug manifested about 50% of the time, so try it a few times.
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for i := 0; i < 10; i++ {
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try()
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}
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}
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@ -104,13 +104,17 @@ func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-c
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}
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if cancel != nil {
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done := make(chan bool)
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defer close(done)
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defer func() {
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// This is unbuffered; wait for the goroutine before returning.
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done <- true
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}()
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go func() {
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select {
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case <-cancel:
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// Force the runtime's poller to immediately give
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// up waiting for writability.
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fd.setWriteDeadline(aLongTimeAgo)
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<-done
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case <-done:
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}
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}()
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@ -352,14 +352,18 @@ func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-c
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o := &fd.wop
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o.sa = ra
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if cancel != nil {
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done := make(chan struct{})
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defer close(done)
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done := make(chan bool)
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defer func() {
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// This is unbuffered; wait for the goroutine before returning.
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done <- true
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}()
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go func() {
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select {
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case <-cancel:
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// Force the runtime's poller to immediately give
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// up waiting for writability.
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fd.setWriteDeadline(aLongTimeAgo)
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<-done
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case <-done:
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}
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}()
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