forked from ghetzel/go-stockutil
/
nettest.go
120 lines (112 loc) · 3.63 KB
/
nettest.go
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// Copyright 2012 The Go Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package netutil
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
}
// Returns the first routable address on the given interface.
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 := IsRoutableIP(network, ifa.IP); ip != nil {
return ip, true
}
case *net.IPNet:
if ip := IsRoutableIP(network, ifa.IP); ip != nil {
return ip, true
}
}
}
return nil, false
}
// Returns true when the given address is unicast routable beyond the current machine.
func IsRoutableIP(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
}