net: fix EAI_BADFLAGS error on freebsd

R=rsc
CC=golang-dev
https://golang.org/cl/4442072

src/pkg/net/Makefile

@@ -31,6 +31,7 @@ GOFILES_freebsd=\
 	port.go\
 
 CGOFILES_freebsd=\
+	cgo_bsd.go\
 	cgo_unix.go\
 
 GOFILES_darwin=\
@@ -42,6 +43,7 @@ GOFILES_darwin=\
 	port.go\
 
 CGOFILES_darwin=\
+	cgo_bsd.go\
 	cgo_unix.go\
 	
 GOFILES_linux=\
@@ -57,6 +59,7 @@ ifeq ($(GOARCH),arm)
 GOFILES_linux+=cgo_stub.go
 else
 CGOFILES_linux=\
+	cgo_linux.go\
 	cgo_unix.go
 endif
 

src/pkg/net/cgo_bsd.go

@@ -0,0 +1,14 @@
+// Copyright 2011 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.
+
+package net
+
+/*
+#include <netdb.h>
+*/
+import "C"
+
+func cgoAddrInfoMask() C.int {
+	return C.AI_MASK
+}

src/pkg/net/cgo_linux.go

@@ -0,0 +1,14 @@
+// Copyright 2011 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.
+
+package net
+
+/*
+#include <netdb.h>
+*/
+import "C"
+
+func cgoAddrInfoMask() C.int {
+	return C.AI_CANONNAME | C.AI_V4MAPPED | C.AI_ALL
+}

src/pkg/net/cgo_unix.go

@@ -86,7 +86,7 @@ func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err os.Error, comp
 	// and similarly for IPv6), but in practice setting it causes
 	// getaddrinfo to return the wrong canonical name on Linux.
 	// So definitely leave it out.
-	hints.ai_flags = C.AI_ALL | C.AI_V4MAPPED | C.AI_CANONNAME
+	hints.ai_flags = (C.AI_ALL | C.AI_V4MAPPED | C.AI_CANONNAME) & cgoAddrInfoMask()
 
 	h := C.CString(name)
 	defer C.free(unsafe.Pointer(h))