code review 6482044: go.net/ipv4: new package

ipv4/sockopt_freebsd.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.
+
+package ipv4
+
+import (
+        "os"
+        "syscall"
+)
+
+func ipv4SendSourceAddress(fd int) (bool, error) {
+        v, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_SENDSRCADDR)
+        if err != nil {
+                return false, os.NewSyscallError("getsockopt", err)
+        }
+        return v == 1, nil
+}
+
+func setIPv4SendSourceAddress(fd int, v bool) error {
+        err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_SENDSRCADDR, boolint(v))
+        if err != nil {
+                return os.NewSyscallError("setsockopt", err)
+        }
+        return nil
+}