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/mockicmp_test.go b/ipv4/mockicmp_test.go
new file mode 100644
index 0000000..5bf8920
--- /dev/null
+++ b/ipv4/mockicmp_test.go
@@ -0,0 +1,47 @@
+// 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_test
+
+import (
+ "bytes"
+ "flag"
+)
+
+var testExternal = flag.Bool("external", true, "allow use of external networks during long test")
+
+func newICMPEchoRequest(id, seqnum, msglen int, filler []byte) []byte {
+ b := newICMPInfoMessage(id, seqnum, msglen, filler)
+ b[0] = 8
+ // calculate ICMP checksum
+ cklen := len(b)
+ s := uint32(0)
+ for i := 0; i < cklen-1; i += 2 {
+ s += uint32(b[i+1])<<8 | uint32(b[i])
+ }
+ if cklen&1 == 1 {
+ s += uint32(b[cklen-1])
+ }
+ s = (s >> 16) + (s & 0xffff)
+ s = s + (s >> 16)
+ // place checksum back in header; using ^= avoids the
+ // assumption the checksum bytes are zero
+ b[2] ^= byte(^s & 0xff)
+ b[3] ^= byte(^s >> 8)
+ return b
+}
+
+func newICMPInfoMessage(id, seqnum, msglen int, filler []byte) []byte {
+ b := make([]byte, msglen)
+ copy(b[8:], bytes.Repeat(filler, (msglen-8)/len(filler)+1))
+ b[0] = 0 // type
+ b[1] = 0 // code
+ b[2] = 0 // checksum
+ b[3] = 0 // checksum
+ b[4] = byte(id >> 8) // identifier
+ b[5] = byte(id & 0xff) // identifier
+ b[6] = byte(seqnum >> 8) // sequence number
+ b[7] = byte(seqnum & 0xff) // sequence number
+ return b
+}
