syncthing/lib/pmp/pmp.go

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// Copyright (C) 2016 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
package pmp
import (
"fmt"
"net"
"strings"
"time"
"github.com/AudriusButkevicius/go-nat-pmp"
"github.com/calmh/gateway"
"github.com/syncthing/syncthing/lib/nat"
)
func init() {
nat.Register(Discover)
}
func Discover(renewal, timeout time.Duration) []nat.Device {
ip, err := gateway.DiscoverGateway()
if err != nil {
l.Debugln("Failed to discover gateway", err)
return nil
}
if ip == nil || ip.IsUnspecified() {
return nil
}
l.Debugln("Discovered gateway at", ip)
c := natpmp.NewClient(ip, timeout)
// Try contacting the gateway, if it does not respond, assume it does not
// speak NAT-PMP.
_, err = c.GetExternalAddress()
if err != nil && strings.Contains(err.Error(), "Timed out") {
l.Debugln("Timeout trying to get external address, assume no NAT-PMP available")
return nil
}
var localIP net.IP
// Port comes from the natpmp package
conn, err := net.DialTimeout("udp", net.JoinHostPort(ip.String(), "5351"), timeout)
if err == nil {
conn.Close()
localIPAddress, _, err := net.SplitHostPort(conn.LocalAddr().String())
if err == nil {
localIP = net.ParseIP(localIPAddress)
} else {
l.Debugln("Failed to lookup local IP", err)
}
}
return []nat.Device{&wrapper{
renewal: renewal,
localIP: localIP,
gatewayIP: ip,
client: c,
}}
}
type wrapper struct {
renewal time.Duration
localIP net.IP
gatewayIP net.IP
client *natpmp.Client
}
func (w *wrapper) ID() string {
return fmt.Sprintf("NAT-PMP@%s", w.gatewayIP.String())
}
func (w *wrapper) GetLocalIPAddress() net.IP {
return w.localIP
}
func (w *wrapper) AddPortMapping(protocol nat.Protocol, internalPort, externalPort int, description string, duration time.Duration) (int, error) {
// NAT-PMP says that if duration is 0, the mapping is actually removed
// Swap the zero with the renewal value, which should make the lease for the
// exact amount of time between the calls.
if duration == 0 {
duration = w.renewal
}
result, err := w.client.AddPortMapping(strings.ToLower(string(protocol)), internalPort, externalPort, int(duration/time.Second))
port := 0
if result != nil {
port = int(result.MappedExternalPort)
}
return port, err
}
func (w *wrapper) GetExternalIPAddress() (net.IP, error) {
result, err := w.client.GetExternalAddress()
ip := net.IPv4zero
if result != nil {
ip = net.IPv4(
result.ExternalIPAddress[0],
result.ExternalIPAddress[1],
result.ExternalIPAddress[2],
result.ExternalIPAddress[3],
)
}
return ip, err
}