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/mocktransponder_test.go b/ipv4/mocktransponder_test.go
new file mode 100644
index 0000000..99759ef
--- /dev/null
+++ b/ipv4/mocktransponder_test.go
@@ -0,0 +1,133 @@
+// 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
+
+package ipv4_test
+
+import (
+ "code.google.com/p/go.net/ipv4"
+ "net"
+ "testing"
+ "time"
+)
+
+// runPayloadTransponder transmits IPv4 datagram payloads to the
+// loopback address or interface and captures the loopback'd datagram
+// payloads.
+func runPayloadTransponder(t *testing.T, c *ipv4.PacketConn, wb []byte, dst net.Addr) {
+ cf := ipv4.FlagTTL | ipv4.FlagDst | ipv4.FlagInterface
+ rb := make([]byte, 1500)
+ for i, toggle := range []bool{true, false, true} {
+ if err := c.SetControlMessage(cf, toggle); err != nil {
+ t.Fatalf("ipv4.PacketConn.SetControlMessage failed: %v", err)
+ }
+ c.SetTOS(i + 1)
+ var ip net.IP
+ switch v := dst.(type) {
+ case *net.UDPAddr:
+ ip = v.IP
+ case *net.IPAddr:
+ ip = v.IP
+ }
+ if ip.IsMulticast() {
+ c.SetMulticastTTL(i + 1)
+ } else {
+ c.SetTTL(i + 1)
+ }
+ c.SetDeadline(time.Now().Add(100 * time.Millisecond))
+ if _, err := c.Write(wb, nil, dst); err != nil {
+ t.Fatalf("ipv4.PacketConn.Write failed: %v", err)
+ }
+ _, cm, _, err := c.Read(rb)
+ if err != nil {
+ t.Fatalf("ipv4.PacketConn.Read failed: %v", err)
+ }
+ t.Logf("rcvd cmsg: %v", cm)
+ }
+}
+
+// runDatagramTransponder transmits ICMP for IPv4 datagrams to the
+// loopback address or interface and captures the response datagrams
+// from the protocol stack within the kernel.
+func runDatagramTransponder(t *testing.T, c *ipv4.RawConn, wb []byte, src, dst net.Addr) {
+ cf := ipv4.FlagTTL | ipv4.FlagDst | ipv4.FlagInterface
+ rb := make([]byte, ipv4.HeaderLen+len(wb))
+ for i, toggle := range []bool{true, false, true} {
+ if err := c.SetControlMessage(cf, toggle); err != nil {
+ t.Fatalf("ipv4.RawConn.SetControlMessage failed: %v", err)
+ }
+ wh := &ipv4.Header{}
+ wh.Version = ipv4.Version
+ wh.Len = ipv4.HeaderLen
+ wh.TOS = i + 1
+ wh.TotalLen = ipv4.HeaderLen + len(wb)
+ wh.TTL = i + 1
+ wh.Protocol = 1
+ if src != nil {
+ wh.Src = src.(*net.IPAddr).IP
+ }
+ if dst != nil {
+ wh.Dst = dst.(*net.IPAddr).IP
+ }
+ c.SetDeadline(time.Now().Add(100 * time.Millisecond))
+ if err := c.Write(wh, wb, nil); err != nil {
+ t.Fatalf("ipv4.RawConn.Write failed: %v", err)
+ }
+ rh, _, cm, err := c.Read(rb)
+ if err != nil {
+ t.Fatalf("ipv4.RawConn.Read failed: %v", err)
+ }
+ t.Logf("rcvd cmsg: %v", cm.String())
+ t.Logf("rcvd hdr: %v", rh.String())
+ }
+}
+
+func loopbackInterface() *net.Interface {
+ ift, err := net.Interfaces()
+ if err != nil {
+ return nil
+ }
+ for _, ifi := range ift {
+ if ifi.Flags&net.FlagLoopback != 0 {
+ return &ifi
+ }
+ }
+ return nil
+}
+
+func isGoodForMulticast(ifi *net.Interface) (net.IP, bool) {
+ if ifi.Flags&net.FlagUp == 0 {
+ return nil, false
+ }
+ // We need a unicast IPv4 address that can be used to specify
+ // the IPv4 multicast interface.
+ ifat, err := ifi.Addrs()
+ if err != nil {
+ return nil, false
+ }
+ if len(ifat) == 0 {
+ return nil, false
+ }
+ var ip net.IP
+ for _, ifa := range ifat {
+ switch v := ifa.(type) {
+ case *net.IPAddr:
+ ip = v.IP
+ case *net.IPNet:
+ ip = v.IP
+ default:
+ continue
+ }
+ if ip.To4() == nil {
+ ip = nil
+ continue
+ }
+ break
+ }
+ if ip == nil {
+ return nil, false
+ }
+ return ip, true
+}
