go.net/ipv4: new package
Package ipv4 implements IP-level socket options for the Internet
Protocol version 4. It also provides raw IP socket access methods
including IPv4 header manipulation.
Fixes golang/go#3684.
Fixes golang/go#3820.
This CL requires CL 6426047;
net: add read, write message methods to IPConn, UDPConn
R=rsc, dave, alex.brainman
CC=gobot, golang-dev
https://golang.org/cl/6482044
diff --git a/ipv4/helper_posix.go b/ipv4/helper_posix.go
new file mode 100644
index 0000000..0adb3e1
--- /dev/null
+++ b/ipv4/helper_posix.go
@@ -0,0 +1,42 @@
+// 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.
+
+// +build darwin freebsd linux netbsd openbsd windows
+
+package ipv4
+
+import (
+ "bytes"
+ "net"
+ "syscall"
+)
+
+func setSyscallIPMreq(mreq *syscall.IPMreq, ifi *net.Interface) error {
+ if ifi == nil {
+ return nil
+ }
+ ifat, err := ifi.Addrs()
+ if err != nil {
+ return err
+ }
+ for _, ifa := range ifat {
+ switch v := ifa.(type) {
+ case *net.IPAddr:
+ if a := v.IP.To4(); a != nil {
+ copy(mreq.Interface[:], a)
+ goto done
+ }
+ case *net.IPNet:
+ if a := v.IP.To4(); a != nil {
+ copy(mreq.Interface[:], a)
+ goto done
+ }
+ }
+ }
+done:
+ if bytes.Equal(mreq.Multiaddr[:], net.IPv4zero.To4()) {
+ return errNoSuchMulticastInterface
+ }
+ return nil
+}
