60ecf48dd4
This changes the port mapping procedure such that, when the requested port is unavailable an alternative port suggested by the router is used instead. We now also repeatedly request the external IP from the router in order to catch any IP changes. Co-authored-by: Felix Lange <fjl@twurst.com>
131 lines
3.5 KiB
Go
131 lines
3.5 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package nat
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import (
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"fmt"
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"net"
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"strings"
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"time"
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natpmp "github.com/jackpal/go-nat-pmp"
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)
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// natPMPClient adapts the NAT-PMP protocol implementation so it conforms to
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// the common interface.
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type pmp struct {
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gw net.IP
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c *natpmp.Client
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}
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func (n *pmp) String() string {
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return fmt.Sprintf("NAT-PMP(%v)", n.gw)
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}
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func (n *pmp) ExternalIP() (net.IP, error) {
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response, err := n.c.GetExternalAddress()
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if err != nil {
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return nil, err
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}
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return response.ExternalIPAddress[:], nil
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}
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func (n *pmp) AddMapping(protocol string, extport, intport int, name string, lifetime time.Duration) (uint16, error) {
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if lifetime <= 0 {
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return 0, fmt.Errorf("lifetime must not be <= 0")
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}
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// Note order of port arguments is switched between our
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// AddMapping and the client's AddPortMapping.
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res, err := n.c.AddPortMapping(strings.ToLower(protocol), intport, extport, int(lifetime/time.Second))
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if err != nil {
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return 0, err
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}
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// NAT-PMP maps an alternative available port number if the requested port
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// is already mapped to another address and returns success. Handling of
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// alternate port numbers is done by the caller.
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return res.MappedExternalPort, nil
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}
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func (n *pmp) DeleteMapping(protocol string, extport, intport int) (err error) {
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// To destroy a mapping, send an add-port with an internalPort of
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// the internal port to destroy, an external port of zero and a
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// time of zero.
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_, err = n.c.AddPortMapping(strings.ToLower(protocol), intport, 0, 0)
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return err
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}
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func discoverPMP() Interface {
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// run external address lookups on all potential gateways
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gws := potentialGateways()
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found := make(chan *pmp, len(gws))
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for i := range gws {
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gw := gws[i]
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go func() {
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c := natpmp.NewClient(gw)
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if _, err := c.GetExternalAddress(); err != nil {
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found <- nil
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} else {
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found <- &pmp{gw, c}
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}
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}()
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}
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// return the one that responds first.
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// discovery needs to be quick, so we stop caring about
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// any responses after a very short timeout.
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timeout := time.NewTimer(1 * time.Second)
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defer timeout.Stop()
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for range gws {
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select {
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case c := <-found:
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if c != nil {
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return c
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}
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case <-timeout.C:
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return nil
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}
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}
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return nil
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}
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// TODO: improve this. We currently assume that (on most networks)
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// the router is X.X.X.1 in a local LAN range.
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func potentialGateways() (gws []net.IP) {
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ifaces, 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 _, iface := range ifaces {
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ifaddrs, err := iface.Addrs()
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if err != nil {
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return gws
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}
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for _, addr := range ifaddrs {
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if x, ok := addr.(*net.IPNet); ok {
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if x.IP.IsPrivate() {
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ip := x.IP.Mask(x.Mask).To4()
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if ip != nil {
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ip[3] = ip[3] | 0x01
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gws = append(gws, ip)
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}
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}
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}
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}
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}
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return gws
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}
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