479 lines
14 KiB
Go
479 lines
14 KiB
Go
// Copyright (C) 2015 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at http://mozilla.org/MPL/2.0/.
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package connections
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import (
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"crypto/tls"
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"fmt"
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"io"
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"net"
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"net/url"
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"sync"
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"time"
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"github.com/juju/ratelimit"
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"github.com/syncthing/syncthing/lib/config"
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"github.com/syncthing/syncthing/lib/discover"
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"github.com/syncthing/syncthing/lib/events"
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"github.com/syncthing/syncthing/lib/model"
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"github.com/syncthing/syncthing/lib/protocol"
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"github.com/syncthing/syncthing/lib/relay"
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"github.com/syncthing/syncthing/lib/relay/client"
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"github.com/thejerf/suture"
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)
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type DialerFactory func(*url.URL, *tls.Config) (*tls.Conn, error)
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type ListenerFactory func(*url.URL, *tls.Config, chan<- model.IntermediateConnection)
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var (
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dialers = make(map[string]DialerFactory, 0)
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listeners = make(map[string]ListenerFactory, 0)
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)
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type Model interface {
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protocol.Model
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AddConnection(conn model.Connection)
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ConnectedTo(remoteID protocol.DeviceID) bool
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IsPaused(remoteID protocol.DeviceID) bool
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}
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// The connection connectionService listens on TLS and dials configured unconnected
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// devices. Successful connections are handed to the model.
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type connectionService struct {
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*suture.Supervisor
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cfg *config.Wrapper
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myID protocol.DeviceID
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model Model
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tlsCfg *tls.Config
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discoverer discover.Finder
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conns chan model.IntermediateConnection
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relayService *relay.Service
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bepProtocolName string
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tlsDefaultCommonName string
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lans []*net.IPNet
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writeRateLimit *ratelimit.Bucket
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readRateLimit *ratelimit.Bucket
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lastRelayCheck map[protocol.DeviceID]time.Time
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mut sync.RWMutex
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connType map[protocol.DeviceID]model.ConnectionType
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relaysEnabled bool
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}
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func NewConnectionService(cfg *config.Wrapper, myID protocol.DeviceID, mdl Model, tlsCfg *tls.Config, discoverer discover.Finder, relayService *relay.Service,
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bepProtocolName string, tlsDefaultCommonName string, lans []*net.IPNet) suture.Service {
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service := &connectionService{
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Supervisor: suture.NewSimple("connectionService"),
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cfg: cfg,
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myID: myID,
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model: mdl,
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tlsCfg: tlsCfg,
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discoverer: discoverer,
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relayService: relayService,
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conns: make(chan model.IntermediateConnection),
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bepProtocolName: bepProtocolName,
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tlsDefaultCommonName: tlsDefaultCommonName,
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lans: lans,
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connType: make(map[protocol.DeviceID]model.ConnectionType),
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relaysEnabled: cfg.Options().RelaysEnabled,
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lastRelayCheck: make(map[protocol.DeviceID]time.Time),
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}
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cfg.Subscribe(service)
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if service.cfg.Options().MaxSendKbps > 0 {
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service.writeRateLimit = ratelimit.NewBucketWithRate(float64(1000*service.cfg.Options().MaxSendKbps), int64(5*1000*service.cfg.Options().MaxSendKbps))
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}
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if service.cfg.Options().MaxRecvKbps > 0 {
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service.readRateLimit = ratelimit.NewBucketWithRate(float64(1000*service.cfg.Options().MaxRecvKbps), int64(5*1000*service.cfg.Options().MaxRecvKbps))
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}
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// There are several moving parts here; one routine per listening address
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// to handle incoming connections, one routine to periodically attempt
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// outgoing connections, one routine to the the common handling
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// regardless of whether the connection was incoming or outgoing.
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// Furthermore, a relay connectionService which handles incoming requests to connect
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// via the relays.
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//
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// TODO: Clean shutdown, and/or handling config changes on the fly. We
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// partly do this now - new devices and addresses will be picked up, but
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// not new listen addresses and we don't support disconnecting devices
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// that are removed and so on...
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service.Add(serviceFunc(service.connect))
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for _, addr := range service.cfg.Options().ListenAddress {
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uri, err := url.Parse(addr)
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if err != nil {
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l.Infoln("Failed to parse listen address:", addr, err)
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continue
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}
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listener, ok := listeners[uri.Scheme]
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if !ok {
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l.Infoln("Unknown listen address scheme:", uri.String())
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continue
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}
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l.Debugln("listening on", uri)
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service.Add(serviceFunc(func() {
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listener(uri, service.tlsCfg, service.conns)
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}))
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}
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service.Add(serviceFunc(service.handle))
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if service.relayService != nil {
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service.Add(serviceFunc(service.acceptRelayConns))
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}
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return service
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}
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func (s *connectionService) handle() {
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next:
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for c := range s.conns {
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cs := c.Conn.ConnectionState()
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// We should have negotiated the next level protocol "bep/1.0" as part
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// of the TLS handshake. Unfortunately this can't be a hard error,
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// because there are implementations out there that don't support
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// protocol negotiation (iOS for one...).
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if !cs.NegotiatedProtocolIsMutual || cs.NegotiatedProtocol != s.bepProtocolName {
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l.Infof("Peer %s did not negotiate bep/1.0", c.Conn.RemoteAddr())
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}
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// We should have received exactly one certificate from the other
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// side. If we didn't, they don't have a device ID and we drop the
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// connection.
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certs := cs.PeerCertificates
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if cl := len(certs); cl != 1 {
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l.Infof("Got peer certificate list of length %d != 1 from %s; protocol error", cl, c.Conn.RemoteAddr())
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c.Conn.Close()
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continue
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}
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remoteCert := certs[0]
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remoteID := protocol.NewDeviceID(remoteCert.Raw)
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// The device ID should not be that of ourselves. It can happen
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// though, especially in the presence of NAT hairpinning, multiple
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// clients between the same NAT gateway, and global discovery.
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if remoteID == s.myID {
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l.Infof("Connected to myself (%s) - should not happen", remoteID)
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c.Conn.Close()
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continue
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}
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// If we have a relay connection, and the new incoming connection is
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// not a relay connection, we should drop that, and prefer the this one.
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s.mut.RLock()
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ct, ok := s.connType[remoteID]
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s.mut.RUnlock()
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if ok && !ct.IsDirect() && c.Type.IsDirect() {
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l.Debugln("Switching connections", remoteID)
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s.model.Close(remoteID, fmt.Errorf("switching connections"))
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} else if s.model.ConnectedTo(remoteID) {
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// We should not already be connected to the other party. TODO: This
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// could use some better handling. If the old connection is dead but
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// hasn't timed out yet we may want to drop *that* connection and keep
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// this one. But in case we are two devices connecting to each other
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// in parallel we don't want to do that or we end up with no
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// connections still established...
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l.Infof("Connected to already connected device (%s)", remoteID)
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c.Conn.Close()
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continue
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} else if s.model.IsPaused(remoteID) {
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l.Infof("Connection from paused device (%s)", remoteID)
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c.Conn.Close()
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continue
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}
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for deviceID, deviceCfg := range s.cfg.Devices() {
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if deviceID == remoteID {
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// Verify the name on the certificate. By default we set it to
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// "syncthing" when generating, but the user may have replaced
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// the certificate and used another name.
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certName := deviceCfg.CertName
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if certName == "" {
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certName = s.tlsDefaultCommonName
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}
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err := remoteCert.VerifyHostname(certName)
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if err != nil {
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// Incorrect certificate name is something the user most
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// likely wants to know about, since it's an advanced
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// config. Warn instead of Info.
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l.Warnf("Bad certificate from %s (%v): %v", remoteID, c.Conn.RemoteAddr(), err)
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c.Conn.Close()
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continue next
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}
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// If rate limiting is set, and based on the address we should
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// limit the connection, then we wrap it in a limiter.
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limit := s.shouldLimit(c.Conn.RemoteAddr())
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wr := io.Writer(c.Conn)
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if limit && s.writeRateLimit != nil {
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wr = NewWriteLimiter(c.Conn, s.writeRateLimit)
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}
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rd := io.Reader(c.Conn)
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if limit && s.readRateLimit != nil {
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rd = NewReadLimiter(c.Conn, s.readRateLimit)
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}
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name := fmt.Sprintf("%s-%s (%s)", c.Conn.LocalAddr(), c.Conn.RemoteAddr(), c.Type)
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protoConn := protocol.NewConnection(remoteID, rd, wr, s.model, name, deviceCfg.Compression)
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l.Infof("Established secure connection to %s at %s", remoteID, name)
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l.Debugf("cipher suite: %04X in lan: %t", c.Conn.ConnectionState().CipherSuite, !limit)
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s.model.AddConnection(model.Connection{
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c.Conn,
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protoConn,
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c.Type,
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})
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s.mut.Lock()
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s.connType[remoteID] = c.Type
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s.mut.Unlock()
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continue next
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}
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}
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if !s.cfg.IgnoredDevice(remoteID) {
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events.Default.Log(events.DeviceRejected, map[string]string{
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"device": remoteID.String(),
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"address": c.Conn.RemoteAddr().String(),
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})
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}
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l.Infof("Connection from %s (%s) with ignored device ID %s", c.Conn.RemoteAddr(), c.Type, remoteID)
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c.Conn.Close()
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}
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}
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func (s *connectionService) connect() {
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delay := time.Second
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for {
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l.Debugln("Reconnect loop")
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nextDevice:
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for deviceID, deviceCfg := range s.cfg.Devices() {
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if deviceID == s.myID {
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continue
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}
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l.Debugln("Reconnect loop for", deviceID)
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if s.model.IsPaused(deviceID) {
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continue
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}
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connected := s.model.ConnectedTo(deviceID)
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s.mut.RLock()
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ct, ok := s.connType[deviceID]
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relaysEnabled := s.relaysEnabled
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s.mut.RUnlock()
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if connected && ok && ct.IsDirect() {
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l.Debugln("Already connected to", deviceID, "via", ct.String())
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continue
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}
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addrs, relays := s.resolveAddresses(deviceID, deviceCfg.Addresses)
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for _, addr := range addrs {
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if conn := s.connectDirect(deviceID, addr); conn != nil {
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l.Debugln("Connecting to", deviceID, "via", addr, "succeeded")
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if connected {
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s.model.Close(deviceID, fmt.Errorf("switching connections"))
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}
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s.conns <- model.IntermediateConnection{
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conn, model.ConnectionTypeDirectDial,
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}
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continue nextDevice
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}
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l.Debugln("Connecting to", deviceID, "via", addr, "failed")
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}
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// Only connect via relays if not already connected
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// Also, do not set lastRelayCheck time if we have no relays,
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// as otherwise when we do discover relays, we might have to
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// wait up to RelayReconnectIntervalM to connect again.
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// Also, do not try relays if we are explicitly told not to.
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if connected || len(relays) == 0 || !relaysEnabled {
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l.Debugln("Not connecting via relay", connected, len(relays) == 0, !relaysEnabled)
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continue nextDevice
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}
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reconIntv := time.Duration(s.cfg.Options().RelayReconnectIntervalM) * time.Minute
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if last, ok := s.lastRelayCheck[deviceID]; ok && time.Since(last) < reconIntv {
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l.Debugln("Skipping connecting via relay to", deviceID, "last checked at", last)
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continue nextDevice
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}
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l.Debugln("Trying relay connections to", deviceID, relays)
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s.lastRelayCheck[deviceID] = time.Now()
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for _, addr := range relays {
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if conn := s.connectViaRelay(deviceID, addr); conn != nil {
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l.Debugln("Connecting to", deviceID, "via", addr, "succeeded")
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s.conns <- model.IntermediateConnection{
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conn, model.ConnectionTypeRelayDial,
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}
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continue nextDevice
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}
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l.Debugln("Connecting to", deviceID, "via", addr, "failed")
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}
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}
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time.Sleep(delay)
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delay *= 2
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if maxD := time.Duration(s.cfg.Options().ReconnectIntervalS) * time.Second; delay > maxD {
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delay = maxD
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}
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}
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}
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func (s *connectionService) resolveAddresses(deviceID protocol.DeviceID, inAddrs []string) (addrs []string, relays []discover.Relay) {
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for _, addr := range inAddrs {
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if addr == "dynamic" {
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if s.discoverer != nil {
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if t, r, err := s.discoverer.Lookup(deviceID); err == nil {
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addrs = append(addrs, t...)
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relays = append(relays, r...)
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}
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}
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} else {
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addrs = append(addrs, addr)
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}
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}
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return
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}
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func (s *connectionService) connectDirect(deviceID protocol.DeviceID, addr string) *tls.Conn {
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uri, err := url.Parse(addr)
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if err != nil {
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l.Infoln("Failed to parse connection url:", addr, err)
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return nil
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}
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dialer, ok := dialers[uri.Scheme]
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if !ok {
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l.Infoln("Unknown address schema", uri)
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return nil
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}
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l.Debugln("dial", deviceID, uri)
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conn, err := dialer(uri, s.tlsCfg)
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if err != nil {
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l.Debugln("dial failed", deviceID, uri, err)
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return nil
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}
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return conn
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}
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func (s *connectionService) connectViaRelay(deviceID protocol.DeviceID, addr discover.Relay) *tls.Conn {
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uri, err := url.Parse(addr.URL)
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if err != nil {
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l.Infoln("Failed to parse relay connection url:", addr, err)
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return nil
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}
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inv, err := client.GetInvitationFromRelay(uri, deviceID, s.tlsCfg.Certificates, 10*time.Second)
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if err != nil {
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l.Debugf("Failed to get invitation for %s from %s: %v", deviceID, uri, err)
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return nil
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}
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l.Debugln("Succesfully retrieved relay invitation", inv, "from", uri)
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conn, err := client.JoinSession(inv)
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if err != nil {
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l.Debugf("Failed to join relay session %s: %v", inv, err)
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return nil
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}
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l.Debugln("Successfully joined relay session", inv)
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var tc *tls.Conn
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if inv.ServerSocket {
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tc = tls.Server(conn, s.tlsCfg)
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} else {
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tc = tls.Client(conn, s.tlsCfg)
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}
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err = tc.Handshake()
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if err != nil {
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l.Infof("TLS handshake (BEP/relay %s): %v", inv, err)
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tc.Close()
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return nil
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}
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return tc
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}
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func (s *connectionService) acceptRelayConns() {
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for {
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conn := s.relayService.Accept()
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s.conns <- model.IntermediateConnection{
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Conn: conn,
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Type: model.ConnectionTypeRelayAccept,
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}
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}
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}
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func (s *connectionService) shouldLimit(addr net.Addr) bool {
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if s.cfg.Options().LimitBandwidthInLan {
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return true
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}
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tcpaddr, ok := addr.(*net.TCPAddr)
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if !ok {
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return true
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}
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for _, lan := range s.lans {
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if lan.Contains(tcpaddr.IP) {
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return false
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}
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}
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return !tcpaddr.IP.IsLoopback()
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}
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func (s *connectionService) VerifyConfiguration(from, to config.Configuration) error {
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return nil
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}
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func (s *connectionService) CommitConfiguration(from, to config.Configuration) bool {
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s.mut.Lock()
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s.relaysEnabled = to.Options.RelaysEnabled
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s.mut.Unlock()
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// We require a restart if a device as been removed.
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newDevices := make(map[protocol.DeviceID]bool, len(to.Devices))
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for _, dev := range to.Devices {
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newDevices[dev.DeviceID] = true
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}
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for _, dev := range from.Devices {
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if !newDevices[dev.DeviceID] {
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return false
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}
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}
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return true
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}
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// serviceFunc wraps a function to create a suture.Service without stop
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// functionality.
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type serviceFunc func()
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func (f serviceFunc) Serve() { f() }
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func (f serviceFunc) Stop() {}
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