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/payload.go b/ipv4/payload.go
new file mode 100644
index 0000000..bfcf751
--- /dev/null
+++ b/ipv4/payload.go
@@ -0,0 +1,81 @@
+// 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 (
+ "net"
+ "syscall"
+)
+
+// A payloadHandler represents the IPv4 datagram payload handler.
+type payloadHandler struct {
+ c net.PacketConn
+ rawOpt
+}
+
+func (c *payloadHandler) ok() bool { return c != nil && c.c != nil }
+
+// Read reads a payload of the received IPv4 datagram, from the
+// endpoint c, copying the payload into b. It returns the number of
+// bytes copied into b, the control message cm and the source address
+// src of the received datagram.
+func (c *payloadHandler) Read(b []byte) (n int, cm *ControlMessage, src net.Addr, err error) {
+ if !c.ok() {
+ return 0, nil, nil, syscall.EINVAL
+ }
+ oob := newControlMessage(&c.rawOpt)
+ var oobn int
+ switch rd := c.c.(type) {
+ case *net.UDPConn:
+ if n, oobn, _, src, err = rd.ReadMsgUDP(b, oob); err != nil {
+ return 0, nil, nil, err
+ }
+ case *net.IPConn:
+ nb := make([]byte, len(b)+maxHeaderLen)
+ if n, oobn, _, src, err = rd.ReadMsgIP(nb, oob); err != nil {
+ return 0, nil, nil, err
+ }
+ hdrlen := (int(b[0]) & 0x0f) << 2
+ copy(b, nb[hdrlen:])
+ n -= hdrlen
+ default:
+ return 0, nil, nil, errInvalidConnType
+ }
+ if cm, err = parseControlMessage(oob[:oobn]); err != nil {
+ return 0, nil, nil, err
+ }
+ if cm != nil {
+ cm.Src = netAddrToIP4(src)
+ }
+ return
+}
+
+// Write writes a payload of the IPv4 datagram, to the destination
+// address dst through the endpoint c, copying the payload from b.
+// It returns the number of bytes written. The control message cm
+// allows the datagram path and the outgoing interface to be
+// specified. Currently only Linux supports this. The cm may be nil
+// if control of the outgoing datagram is not required.
+func (c *payloadHandler) Write(b []byte, cm *ControlMessage, dst net.Addr) (n int, err error) {
+ if !c.ok() {
+ return 0, syscall.EINVAL
+ }
+ oob := marshalControlMessage(cm)
+ if dst == nil {
+ return 0, errMissingAddress
+ }
+ switch wr := c.c.(type) {
+ case *net.UDPConn:
+ n, _, err = wr.WriteMsgUDP(b, oob, dst.(*net.UDPAddr))
+ case *net.IPConn:
+ n, _, err = wr.WriteMsgIP(b, oob, dst.(*net.IPAddr))
+ default:
+ return 0, errInvalidConnType
+ }
+ if err != nil {
+ return 0, err
+ }
+ return
+}
