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|
package nat
import (
"fmt"
"net"
"strings"
"time"
"github.com/jackpal/go-nat-pmp"
)
// natPMPClient adapts the NAT-PMP protocol implementation so it conforms to
// the common interface.
type pmp struct {
gw net.IP
c *natpmp.Client
}
func (n *pmp) String() string {
return fmt.Sprintf("NAT-PMP(%v)", n.gw)
}
func (n *pmp) ExternalIP() (net.IP, error) {
response, err := n.c.GetExternalAddress()
if err != nil {
return nil, err
}
return response.ExternalIPAddress[:], nil
}
func (n *pmp) AddMapping(protocol string, extport, intport int, name string, lifetime time.Duration) error {
if lifetime <= 0 {
return fmt.Errorf("lifetime must not be <= 0")
}
// Note order of port arguments is switched between our
// AddMapping and the client's AddPortMapping.
_, err := n.c.AddPortMapping(strings.ToLower(protocol), intport, extport, int(lifetime/time.Second))
return err
}
func (n *pmp) DeleteMapping(protocol string, extport, intport int) (err error) {
// To destroy a mapping, send an add-port with an internalPort of
// the internal port to destroy, an external port of zero and a
// time of zero.
_, err = n.c.AddPortMapping(strings.ToLower(protocol), intport, 0, 0)
return err
}
func discoverPMP() Interface {
// run external address lookups on all potential gateways
gws := potentialGateways()
found := make(chan *pmp, len(gws))
for i := range gws {
gw := gws[i]
go func() {
c := natpmp.NewClient(gw)
if _, err := c.GetExternalAddress(); err != nil {
found <- nil
} else {
found <- &pmp{gw, c}
}
}()
}
// return the one that responds first.
// discovery needs to be quick, so we stop caring about
// any responses after a very short timeout.
timeout := time.NewTimer(1 * time.Second)
defer timeout.Stop()
for _ = range gws {
select {
case c := <-found:
if c != nil {
return c
}
case <-timeout.C:
return nil
}
}
return nil
}
var (
// LAN IP ranges
_, lan10, _ = net.ParseCIDR("10.0.0.0/8")
_, lan176, _ = net.ParseCIDR("172.16.0.0/12")
_, lan192, _ = net.ParseCIDR("192.168.0.0/16")
)
// TODO: improve this. We currently assume that (on most networks)
// the router is X.X.X.1 in a local LAN range.
func potentialGateways() (gws []net.IP) {
ifaces, err := net.Interfaces()
if err != nil {
return nil
}
for _, iface := range ifaces {
ifaddrs, err := iface.Addrs()
if err != nil {
return gws
}
for _, addr := range ifaddrs {
switch x := addr.(type) {
case *net.IPNet:
if lan10.Contains(x.IP) || lan176.Contains(x.IP) || lan192.Contains(x.IP) {
ip := x.IP.Mask(x.Mask).To4()
if ip != nil {
ip[3] = ip[3] | 0x01
gws = append(gws, ip)
}
}
}
}
}
return gws
}
|
