net: fix "unexpected socket family" error from WriteToUDP.

R=rsc, iant, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/5128048

src/pkg/net/file.go

@@ -22,6 +22,7 @@ func newFileFD(f *os.File) (nfd *netFD, err os.Error) {
 		return nil, os.NewSyscallError("getsockopt", errno)
 	}
 
+	family := syscall.AF_UNSPEC
 	toAddr := sockaddrToTCP
 	sa, _ := syscall.Getsockname(fd)
 	switch sa.(type) {
@@ -29,18 +30,21 @@ func newFileFD(f *os.File) (nfd *netFD, err os.Error) {
 		closesocket(fd)
 		return nil, os.EINVAL
 	case *syscall.SockaddrInet4:
+		family = syscall.AF_INET
 		if proto == syscall.SOCK_DGRAM {
 			toAddr = sockaddrToUDP
 		} else if proto == syscall.SOCK_RAW {
 			toAddr = sockaddrToIP
 		}
 	case *syscall.SockaddrInet6:
+		family = syscall.AF_INET6
 		if proto == syscall.SOCK_DGRAM {
 			toAddr = sockaddrToUDP
 		} else if proto == syscall.SOCK_RAW {
 			toAddr = sockaddrToIP
 		}
 	case *syscall.SockaddrUnix:
+		family = syscall.AF_UNIX
 		toAddr = sockaddrToUnix
 		if proto == syscall.SOCK_DGRAM {
 			toAddr = sockaddrToUnixgram
@@ -52,7 +56,7 @@ func newFileFD(f *os.File) (nfd *netFD, err os.Error) {
 	sa, _ = syscall.Getpeername(fd)
 	raddr := toAddr(sa)
 
-	if nfd, err = newFD(fd, 0, proto, laddr.Network()); err != nil {
+	if nfd, err = newFD(fd, family, proto, laddr.Network()); err != nil {
 		return nil, err
 	}
 	nfd.setAddr(laddr, raddr)

src/pkg/net/file_test.go

@@ -73,7 +73,7 @@ func TestFileListener(t *testing.T) {
 	}
 }
 
-func testFilePacketConn(t *testing.T, pcf packetConnFile) {
+func testFilePacketConn(t *testing.T, pcf packetConnFile, listen bool) {
 	f, err := pcf.File()
 	if err != nil {
 		t.Fatalf("File failed: %v", err)
@@ -85,6 +85,11 @@ func testFilePacketConn(t *testing.T, pcf packetConnFile) {
 	if !reflect.DeepEqual(pcf.LocalAddr(), c.LocalAddr()) {
 		t.Fatalf("LocalAddrs not equal: %#v != %#v", pcf.LocalAddr(), c.LocalAddr())
 	}
+	if listen {
+		if _, err := c.WriteTo([]byte{}, c.LocalAddr()); err != nil {
+			t.Fatalf("WriteTo failed: %v", err)
+		}
+	}
 	if err := c.Close(); err != nil {
 		t.Fatalf("Close failed: %v", err)
 	}
@@ -98,7 +103,7 @@ func testFilePacketConnListen(t *testing.T, net, laddr string) {
 	if err != nil {
 		t.Fatalf("Listen failed: %v", err)
 	}
-	testFilePacketConn(t, l.(packetConnFile))
+	testFilePacketConn(t, l.(packetConnFile), true)
 	if err := l.Close(); err != nil {
 		t.Fatalf("Close failed: %v", err)
 	}
@@ -109,7 +114,7 @@ func testFilePacketConnDial(t *testing.T, net, raddr string) {
 	if err != nil {
 		t.Fatalf("Dial failed: %v", err)
 	}
-	testFilePacketConn(t, c.(packetConnFile))
+	testFilePacketConn(t, c.(packetConnFile), false)
 	if err := c.Close(); err != nil {
 		t.Fatalf("Close failed: %v", err)
 	}