95 lines
2.1 KiB
Go
95 lines
2.1 KiB
Go
// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package nettest
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import "net"
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// IsMulticastCapable reports whether ifi is an IP multicast-capable
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// network interface. Network must be "ip", "ip4" or "ip6".
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func IsMulticastCapable(network string, ifi *net.Interface) (net.IP, bool) {
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switch network {
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case "ip", "ip4", "ip6":
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default:
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return nil, false
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}
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if ifi == nil || ifi.Flags&net.FlagUp == 0 || ifi.Flags&net.FlagMulticast == 0 {
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return nil, false
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}
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return hasRoutableIP(network, ifi)
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}
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// RoutedInterface returns a network interface that can route IP
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// traffic and satisfies flags. It returns nil when an appropriate
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// network interface is not found. Network must be "ip", "ip4" or
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// "ip6".
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func RoutedInterface(network string, flags net.Flags) *net.Interface {
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switch network {
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case "ip", "ip4", "ip6":
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default:
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return nil
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}
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ift, err := net.Interfaces()
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if err != nil {
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return nil
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}
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for _, ifi := range ift {
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if ifi.Flags&flags != flags {
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continue
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}
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if _, ok := hasRoutableIP(network, &ifi); !ok {
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continue
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}
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return &ifi
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}
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return nil
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}
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func hasRoutableIP(network string, ifi *net.Interface) (net.IP, bool) {
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ifat, err := ifi.Addrs()
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if err != nil {
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return nil, false
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}
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for _, ifa := range ifat {
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switch ifa := ifa.(type) {
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case *net.IPAddr:
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if ip := routableIP(network, ifa.IP); ip != nil {
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return ip, true
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}
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case *net.IPNet:
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if ip := routableIP(network, ifa.IP); ip != nil {
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return ip, true
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}
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}
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}
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return nil, false
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}
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func routableIP(network string, ip net.IP) net.IP {
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if !ip.IsLoopback() && !ip.IsLinkLocalUnicast() && !ip.IsGlobalUnicast() {
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return nil
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}
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switch network {
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case "ip4":
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if ip := ip.To4(); ip != nil {
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return ip
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}
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case "ip6":
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if ip.IsLoopback() { // addressing scope of the loopback address depends on each implementation
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return nil
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}
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if ip := ip.To16(); ip != nil && ip.To4() == nil {
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return ip
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}
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default:
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if ip := ip.To4(); ip != nil {
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return ip
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}
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if ip := ip.To16(); ip != nil {
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return ip
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}
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}
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return nil
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}
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