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1// Copyright 2016 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5//go:build unix
6
7package net
8
9import (
10	"context"
11	"errors"
12	"syscall"
13	"testing"
14	"time"
15)
16
17func init() {
18	isEADDRINUSE = func(err error) bool {
19		return errors.Is(err, syscall.EADDRINUSE)
20	}
21}
22
23// Issue 16523
24func TestDialContextCancelRace(t *testing.T) {
25	oldConnectFunc := connectFunc
26	oldGetsockoptIntFunc := getsockoptIntFunc
27	oldTestHookCanceledDial := testHookCanceledDial
28	defer func() {
29		connectFunc = oldConnectFunc
30		getsockoptIntFunc = oldGetsockoptIntFunc
31		testHookCanceledDial = oldTestHookCanceledDial
32	}()
33
34	ln := newLocalListener(t, "tcp")
35	listenerDone := make(chan struct{})
36	go func() {
37		defer close(listenerDone)
38		c, err := ln.Accept()
39		if err == nil {
40			c.Close()
41		}
42	}()
43	defer func() { <-listenerDone }()
44	defer ln.Close()
45
46	sawCancel := make(chan bool, 1)
47	testHookCanceledDial = func() {
48		sawCancel <- true
49	}
50
51	ctx, cancelCtx := context.WithCancel(context.Background())
52
53	connectFunc = func(fd int, addr syscall.Sockaddr) error {
54		err := oldConnectFunc(fd, addr)
55		t.Logf("connect(%d, addr) = %v", fd, err)
56		if err == nil {
57			// On some operating systems, localhost
58			// connects _sometimes_ succeed immediately.
59			// Prevent that, so we exercise the code path
60			// we're interested in testing. This seems
61			// harmless. It makes FreeBSD 10.10 work when
62			// run with many iterations. It failed about
63			// half the time previously.
64			return syscall.EINPROGRESS
65		}
66		return err
67	}
68
69	getsockoptIntFunc = func(fd, level, opt int) (val int, err error) {
70		val, err = oldGetsockoptIntFunc(fd, level, opt)
71		t.Logf("getsockoptIntFunc(%d, %d, %d) = (%v, %v)", fd, level, opt, val, err)
72		if level == syscall.SOL_SOCKET && opt == syscall.SO_ERROR && err == nil && val == 0 {
73			t.Logf("canceling context")
74
75			// Cancel the context at just the moment which
76			// caused the race in issue 16523.
77			cancelCtx()
78
79			// And wait for the "interrupter" goroutine to
80			// cancel the dial by messing with its write
81			// timeout before returning.
82			select {
83			case <-sawCancel:
84				t.Logf("saw cancel")
85			case <-time.After(5 * time.Second):
86				t.Errorf("didn't see cancel after 5 seconds")
87			}
88		}
89		return
90	}
91
92	var d Dialer
93	c, err := d.DialContext(ctx, "tcp", ln.Addr().String())
94	if err == nil {
95		c.Close()
96		t.Fatal("unexpected successful dial; want context canceled error")
97	}
98
99	select {
100	case <-ctx.Done():
101	case <-time.After(5 * time.Second):
102		t.Fatal("expected context to be canceled")
103	}
104
105	oe, ok := err.(*OpError)
106	if !ok || oe.Op != "dial" {
107		t.Fatalf("Dial error = %#v; want dial *OpError", err)
108	}
109
110	if oe.Err != errCanceled {
111		t.Errorf("DialContext = (%v, %v); want OpError with error %v", c, err, errCanceled)
112	}
113}
114