net: ignore EADDRINUSE errors when dialing to IPv4 from IPv6 on FreeBSD

The failure mode in #34264 appears to match
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=210726.

That bug was supposed to have been fixed in FreeBSD 12, but we're
still observing failures specifically for the 6-to-4 case on FreeBSD
12.2. It is not clear to me whether FreeBSD 13.0 is also affected.

For #34264

Change-Id: Iba7c7fc57676ae628b13c0b8fe43ddf2251c3637
Reviewed-on: https://go-review.googlesource.com/c/go/+/369157
Trust: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/net/dial_test.go b/src/net/dial_test.go
index 896789219707529bb639afa48e53403aa89f87bc..36843870aa2795732940be4e949efbb7c9b988d5 100644 (file)
--- a/src/net/dial_test.go
+++ b/src/net/dial_test.go
@@ -537,6 +537,9 @@ func TestDialerPartialDeadline(t *testing.T) {
        }
 }
 
+// isEADDRINUSE reports whether err is syscall.EADDRINUSE.
+var isEADDRINUSE = func(err error) bool { return false }
+
 func TestDialerLocalAddr(t *testing.T) {
        if !supportsIPv4() || !supportsIPv6() {
                t.Skip("both IPv4 and IPv6 are required")
@@ -592,7 +595,9 @@ func TestDialerLocalAddr(t *testing.T) {
                {"tcp", "::1", &UnixAddr{}, &AddrError{Err: "some error"}},
        }
 
+       issue34264Index := -1
        if supportsIPv4map() {
+               issue34264Index = len(tests)
                tests = append(tests, test{
                        "tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, nil,
                })
@@ -627,7 +632,7 @@ func TestDialerLocalAddr(t *testing.T) {
                }
        }
 
-       for _, tt := range tests {
+       for i, tt := range tests {
                d := &Dialer{LocalAddr: tt.laddr}
                var addr string
                ip := ParseIP(tt.raddr)
@@ -639,7 +644,15 @@ func TestDialerLocalAddr(t *testing.T) {
                }
                c, err := d.Dial(tt.network, addr)
                if err == nil && tt.error != nil || err != nil && tt.error == nil {
-                       t.Errorf("%s %v->%s: got %v; want %v", tt.network, tt.laddr, tt.raddr, err, tt.error)
+                       if i == issue34264Index && runtime.GOOS == "freebsd" && isEADDRINUSE(err) {
+                               // https://golang.org/issue/34264: FreeBSD through at least version 12.2
+                               // has been observed to fail with EADDRINUSE when dialing from an IPv6
+                               // local address to an IPv4 remote address.
+                               t.Logf("%s %v->%s: got %v; want %v", tt.network, tt.laddr, tt.raddr, err, tt.error)
+                               t.Logf("(spurious EADDRINUSE ignored on freebsd: see https://golang.org/issue/34264)")
+                       } 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 {

diff --git a/src/net/dial_unix_test.go b/src/net/dial_unix_test.go
index 1113aaca90575b3ae94bc7ba8034c314ec733ad7..64dca70eb85128385946150856074ce84cae05d3 100644 (file)
--- a/src/net/dial_unix_test.go
+++ b/src/net/dial_unix_test.go
@@ -8,11 +8,18 @@ package net
 
 import (
        "context"
+       "errors"
        "syscall"
        "testing"
        "time"
 )
 
+func init() {
+       isEADDRINUSE = func(err error) bool {
+               return errors.Is(err, syscall.EADDRINUSE)
+       }
+}
+
 // Issue 16523
 func TestDialContextCancelRace(t *testing.T) {
        oldConnectFunc := connectFunc