code review 9315043: [release-branch.go1.1] net: fix dial race on plan9 and ...

src/pkg/net/dial_gen.go

 // Copyright 2012 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.
 
 // +build windows plan9
 
 package net
 
 import (
         "time"
 )
 
+var testingIssue5349 bool // used during tests
+
 // resolveAndDialChannel is the simple pure-Go implementation of
 // resolveAndDial, still used on operating systems where the deadline
 // hasn't been pushed down into the pollserver. (Plan 9 and some old
 // versions of Windows)
 func resolveAndDialChannel(net, addr string, localAddr Addr, deadline time.Time) (Conn, error) {
-        timeout := deadline.Sub(time.Now())
-        if timeout < 0 {
-                timeout = 0
+        var timeout time.Duration
+        if !deadline.IsZero() {
+                timeout = deadline.Sub(time.Now())
+        }
+        if timeout <= 0 {
+                ra, err := resolveAddr("dial", net, addr, noDeadline)
+                if err != nil {
+                        return nil, err
+                }
+                return dial(net, addr, localAddr, ra, noDeadline)
         }
         t := time.NewTimer(timeout)
         defer t.Stop()
         type pair struct {
                 Conn
                 error
         }
         ch := make(chan pair, 1)
         resolvedAddr := make(chan Addr, 1)
         go func() {
+                if testingIssue5349 {
+                        time.Sleep(time.Millisecond)
+                }
                 ra, err := resolveAddr("dial", net, addr, noDeadline)
                 if err != nil {
                         ch <- pair{nil, err}
                         return
                 }
                 resolvedAddr <- ra // in case we need it for OpError
                 c, err := dial(net, addr, localAddr, ra, noDeadline)
                 ch <- pair{c, err}
         }()
         select {
@@ skipping 11 matching lines @@
                         Op:   "dial",
                         Net:  net,
                         Addr: ra,
                         Err:  &timeoutError{},
                 }
                 return nil, err
         case p := <-ch:
                 return p.Conn, p.error
         }
 }