lib/connections: Refactor address listing into connection service

lib/upnp/service.go

@@ -0,0 +1,132 @@
+// Copyright (C) 2015 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 upnp
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/syncthing/syncthing/lib/config"
+	"github.com/syncthing/syncthing/lib/events"
+	"github.com/syncthing/syncthing/lib/sync"
+	"github.com/syncthing/syncthing/lib/util"
+)
+
+// Service runs a loop for discovery of IGDs (Internet Gateway Devices) and
+// setup/renewal of a port mapping.
+type Service struct {
+	cfg        *config.Wrapper
+	localPort  int
+	extPort    int
+	extPortMut sync.Mutex
+	stop       chan struct{}
+}
+
+func NewUPnPService(cfg *config.Wrapper, localPort int) *Service {
+	return &Service{
+		cfg:        cfg,
+		localPort:  localPort,
+		extPortMut: sync.NewMutex(),
+	}
+}
+
+func (s *Service) Serve() {
+	foundIGD := true
+	s.stop = make(chan struct{})
+
+	for {
+		igds := Discover(time.Duration(s.cfg.Options().UPnPTimeoutS) * time.Second)
+		if len(igds) > 0 {
+			foundIGD = true
+			s.extPortMut.Lock()
+			oldExtPort := s.extPort
+			s.extPortMut.Unlock()
+
+			newExtPort := s.tryIGDs(igds, oldExtPort)
+
+			s.extPortMut.Lock()
+			s.extPort = newExtPort
+			s.extPortMut.Unlock()
+		} else if foundIGD {
+			// Only print a notice if we've previously found an IGD or this is
+			// the first time around.
+			foundIGD = false
+			l.Infof("No UPnP device detected")
+		}
+
+		d := time.Duration(s.cfg.Options().UPnPRenewalM) * time.Minute
+		if d == 0 {
+			// We always want to do renewal so lets just pick a nice sane number.
+			d = 30 * time.Minute
+		}
+
+		select {
+		case <-s.stop:
+			return
+		case <-time.After(d):
+		}
+	}
+}
+
+func (s *Service) Stop() {
+	close(s.stop)
+}
+
+func (s *Service) ExternalPort() int {
+	s.extPortMut.Lock()
+	port := s.extPort
+	s.extPortMut.Unlock()
+	return port
+}
+
+func (s *Service) tryIGDs(igds []IGD, prevExtPort int) int {
+	// Lets try all the IGDs we found and use the first one that works.
+	// TODO: Use all of them, and sort out the resulting mess to the
+	// discovery announcement code...
+	for _, igd := range igds {
+		extPort, err := s.tryIGD(igd, prevExtPort)
+		if err != nil {
+			l.Warnf("Failed to set UPnP port mapping: external port %d on device %s.", extPort, igd.FriendlyIdentifier())
+			continue
+		}
+
+		if extPort != prevExtPort {
+			l.Infof("New UPnP port mapping: external port %d to local port %d.", extPort, s.localPort)
+			events.Default.Log(events.ExternalPortMappingChanged, map[string]int{"port": extPort})
+		}
+		l.Debugf("Created/updated UPnP port mapping for external port %d on device %s.", extPort, igd.FriendlyIdentifier())
+		return extPort
+	}
+
+	return 0
+}
+
+func (s *Service) tryIGD(igd IGD, suggestedPort int) (int, error) {
+	var err error
+	leaseTime := s.cfg.Options().UPnPLeaseM * 60
+
+	if suggestedPort != 0 {
+		// First try renewing our existing mapping.
+		name := fmt.Sprintf("syncthing-%d", suggestedPort)
+		err = igd.AddPortMapping(TCP, suggestedPort, s.localPort, name, leaseTime)
+		if err == nil {
+			return suggestedPort, nil
+		}
+	}
+
+	for i := 0; i < 10; i++ {
+		// Then try up to ten random ports.
+		extPort := 1024 + util.PredictableRandom.Intn(65535-1024)
+		name := fmt.Sprintf("syncthing-%d", extPort)
+		err = igd.AddPortMapping(TCP, extPort, s.localPort, name, leaseTime)
+		if err == nil {
+			return extPort, nil
+		}
+	}
+
+	return 0, err
+}