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.go b/ipv4/helper.go
new file mode 100644
index 0000000..2cc56bd
--- /dev/null
+++ b/ipv4/helper.go
@@ -0,0 +1,85 @@
+// 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 (
+ "errors"
+ "net"
+)
+
+var (
+ errNoSuchInterface = errors.New("no such interface")
+ errNoSuchMulticastInterface = errors.New("no such multicast interface")
+)
+
+func boolint(b bool) int {
+ if b {
+ return 1
+ }
+ return 0
+}
+
+func netAddrToIP4(a net.Addr) net.IP {
+ switch v := a.(type) {
+ case *net.UDPAddr:
+ if ip := v.IP.To4(); ip != nil {
+ return ip
+ }
+ case *net.IPAddr:
+ if ip := v.IP.To4(); ip != nil {
+ return ip
+ }
+ }
+ return nil
+}
+
+func netIP4ToInterface(ip net.IP) (*net.Interface, error) {
+ ift, err := net.Interfaces()
+ if err != nil {
+ return nil, err
+ }
+ for _, ifi := range ift {
+ ifat, err := ifi.Addrs()
+ if err != nil {
+ return nil, err
+ }
+ for _, ifa := range ifat {
+ switch v := ifa.(type) {
+ case *net.IPAddr:
+ if ip.Equal(v.IP) {
+ return &ifi, nil
+ }
+ case *net.IPNet:
+ if ip.Equal(v.IP) {
+ return &ifi, nil
+ }
+ }
+ }
+ }
+ return nil, errNoSuchInterface
+}
+
+func netInterfaceToIP4(ifi *net.Interface) (net.IP, error) {
+ if ifi == nil {
+ return net.IPv4zero, nil
+ }
+ ifat, err := ifi.Addrs()
+ if err != nil {
+ return nil, err
+ }
+ for _, ifa := range ifat {
+ switch v := ifa.(type) {
+ case *net.IPAddr:
+ if v.IP.To4() != nil {
+ return v.IP, nil
+ }
+ case *net.IPNet:
+ if v.IP.To4() != nil {
+ return v.IP, nil
+ }
+ }
+ }
+ return nil, errNoSuchInterface
+}
