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// 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 nettest
import "net"
// IsMulticastCapable reports whether ifi is an IP multicast-capable
// network interface. Network must be "ip", "ip4" or "ip6".
func IsMulticastCapable(network string, ifi *net.Interface) (net.IP, bool) {
switch network {
case "ip", "ip4", "ip6":
default:
return nil, false
}
if ifi == nil || ifi.Flags&net.FlagUp == 0 || ifi.Flags&net.FlagMulticast == 0 {
return nil, false
}
return hasRoutableIP(network, ifi)
}
// RoutedInterface returns a network interface that can route IP
// traffic and satisfies flags. It returns nil when an appropriate
// network interface is not found. Network must be "ip", "ip4" or
// "ip6".
func RoutedInterface(network string, flags net.Flags) *net.Interface {
switch network {
case "ip", "ip4", "ip6":
default:
return nil
}
ift, err := net.Interfaces()
if err != nil {
return nil
}
for _, ifi := range ift {
if ifi.Flags&flags != flags {
continue
}
if _, ok := hasRoutableIP(network, &ifi); !ok {
continue
}
return &ifi
}
return nil
}
func hasRoutableIP(network string, ifi *net.Interface) (net.IP, bool) {
ifat, err := ifi.Addrs()
if err != nil {
return nil, false
}
for _, ifa := range ifat {
switch ifa := ifa.(type) {
case *net.IPAddr:
if ip := routableIP(network, ifa.IP); ip != nil {
return ip, true
}
case *net.IPNet:
if ip := routableIP(network, ifa.IP); ip != nil {
return ip, true
}
}
}
return nil, false
}
func routableIP(network string, ip net.IP) net.IP {
if !ip.IsLoopback() && !ip.IsLinkLocalUnicast() && !ip.IsGlobalUnicast() {
return nil
}
switch network {
case "ip4":
if ip := ip.To4(); ip != nil {
return ip
}
case "ip6":
if ip.IsLoopback() { // addressing scope of the loopback address depends on each implementation
return nil
}
if ip := ip.To16(); ip != nil && ip.To4() == nil {
return ip
}
default:
if ip := ip.To4(); ip != nil {
return ip
}
if ip := ip.To16(); ip != nil {
return ip
}
}
return nil
}
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