net: prefer an IPv4 listen if no address given

This CL avoids net.Listen("tcp", ":80"), http.ListenAdnServe(":80")
prefer an IPv6 listen.

R=rsc
CC=golang-dev
https://golang.org/cl/5669043

diff --git a/src/pkg/net/dial.go b/src/pkg/net/dial.go
index 5d596bcb6b4b93bee0f337f5784233bade38cbec..61b8911fcf98c474fdbf1fb96058743223a4e7e1 100644 (file)
--- a/src/pkg/net/dial.go
+++ b/src/pkg/net/dial.go
@@ -185,7 +185,7 @@ func Listen(net, laddr string) (Listener, error) {
                if a != nil {
                        la = a.(*TCPAddr)
                }
-               return ListenTCP(afnet, la)
+               return ListenTCP(net, la)
        case "unix", "unixpacket":
                var la *UnixAddr
                if a != nil {

diff --git a/src/pkg/net/ipsock_posix.go b/src/pkg/net/ipsock_posix.go
index 3a059f516bcba10f14600c31b569e1768f7fc894..4da18a5061ac3d3d156bd408a3cfef9fa12fd65a 100644 (file)
--- a/src/pkg/net/ipsock_posix.go
+++ b/src/pkg/net/ipsock_posix.go
@@ -53,13 +53,13 @@ func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
 }
 
 // favoriteAddrFamily returns the appropriate address family to
-// the given net, raddr, laddr and mode.  At first it figures
+// the given net, laddr, raddr and mode.  At first it figures
 // address family out from the net.  If mode indicates "listen"
 // and laddr.(type).IP is nil, it assumes that the user wants to
 // make a passive connection with wildcard address family, both
 // INET and INET6, and wildcard address.  Otherwise guess: if the
 // addresses are IPv4 then returns INET, or else returns INET6.
-func favoriteAddrFamily(net string, raddr, laddr sockaddr, mode string) int {
+func favoriteAddrFamily(net string, laddr, raddr sockaddr, mode string) int {
        switch net[len(net)-1] {
        case '4':
                return syscall.AF_INET
@@ -68,17 +68,20 @@ func favoriteAddrFamily(net string, raddr, laddr sockaddr, mode string) int {
        }
 
        if mode == "listen" {
+               // Note that OpenBSD allows neither "net.inet6.ip6.v6only"
+               // change nor IPPROTO_IPV6 level IPV6_V6ONLY socket option
+               // setting.
                switch a := laddr.(type) {
                case *TCPAddr:
-                       if a.IP == nil && supportsIPv6 {
+                       if a.IP == nil && supportsIPv6 && supportsIPv4map {
                                return syscall.AF_INET6
                        }
                case *UDPAddr:
-                       if a.IP == nil && supportsIPv6 {
+                       if a.IP == nil && supportsIPv6 && supportsIPv4map {
                                return syscall.AF_INET6
                        }
                case *IPAddr:
-                       if a.IP == nil && supportsIPv6 {
+                       if a.IP == nil && supportsIPv6 && supportsIPv4map {
                                return syscall.AF_INET6
                        }
                }
@@ -104,7 +107,7 @@ type sockaddr interface {
 func internetSocket(net string, laddr, raddr sockaddr, sotype, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err error) {
        var oserr error
        var la, ra syscall.Sockaddr
-       family := favoriteAddrFamily(net, raddr, laddr, mode)
+       family := favoriteAddrFamily(net, laddr, raddr, mode)
        if laddr != nil {
                if la, oserr = laddr.sockaddr(family); oserr != nil {
                        goto Error

diff --git a/src/pkg/net/server_test.go b/src/pkg/net/server_test.go
index 1d960565f795978c8fb644b0613f36a001372d82..55691493aa9dc2596530f088cb7e28503116ec4e 100644 (file)
--- a/src/pkg/net/server_test.go
+++ b/src/pkg/net/server_test.go
@@ -115,16 +115,13 @@ func doTest(t *testing.T, network, listenaddr, dialaddr string) {
 }
 
 func TestTCPServer(t *testing.T) {
-       if runtime.GOOS != "openbsd" {
-               doTest(t, "tcp", "", "127.0.0.1")
-       }
+       doTest(t, "tcp", "", "127.0.0.1")
        doTest(t, "tcp", "0.0.0.0", "127.0.0.1")
        doTest(t, "tcp", "127.0.0.1", "127.0.0.1")
        doTest(t, "tcp4", "", "127.0.0.1")
        doTest(t, "tcp4", "0.0.0.0", "127.0.0.1")
        doTest(t, "tcp4", "127.0.0.1", "127.0.0.1")
        if supportsIPv6 {
-               doTest(t, "tcp", "", "[::1]")
                doTest(t, "tcp", "[::]", "[::1]")
                doTest(t, "tcp", "[::1]", "[::1]")
                doTest(t, "tcp6", "", "[::1]")