syncthing/lib/connections/service.go

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// 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 connections
import (
"crypto/tls"
"encoding/binary"
"errors"
"fmt"
"io"
"net"
"net/url"
"time"
"github.com/juju/ratelimit"
"github.com/syncthing/syncthing/lib/config"
"github.com/syncthing/syncthing/lib/discover"
"github.com/syncthing/syncthing/lib/events"
"github.com/syncthing/syncthing/lib/nat"
"github.com/syncthing/syncthing/lib/protocol"
"github.com/syncthing/syncthing/lib/sync"
"github.com/syncthing/syncthing/lib/util"
// Registers NAT service providers
_ "github.com/syncthing/syncthing/lib/pmp"
_ "github.com/syncthing/syncthing/lib/upnp"
"github.com/thejerf/suture"
)
var (
dialers = make(map[string]dialerFactory, 0)
listeners = make(map[string]listenerFactory, 0)
)
// Service listens and dials all configured unconnected devices, via supported
// dialers. Successful connections are handed to the model.
type Service struct {
*suture.Supervisor
cfg *config.Wrapper
myID protocol.DeviceID
model Model
tlsCfg *tls.Config
discoverer discover.Finder
conns chan IntermediateConnection
bepProtocolName string
tlsDefaultCommonName string
lans []*net.IPNet
writeRateLimit *ratelimit.Bucket
readRateLimit *ratelimit.Bucket
natService *nat.Service
natServiceToken *suture.ServiceToken
listenersMut sync.RWMutex
listeners map[string]genericListener
listenerTokens map[string]suture.ServiceToken
curConMut sync.Mutex
currentConnection map[protocol.DeviceID]Connection
}
func NewService(cfg *config.Wrapper, myID protocol.DeviceID, mdl Model, tlsCfg *tls.Config, discoverer discover.Finder,
bepProtocolName string, tlsDefaultCommonName string, lans []*net.IPNet) *Service {
service := &Service{
Supervisor: suture.NewSimple("connections.Service"),
cfg: cfg,
myID: myID,
model: mdl,
tlsCfg: tlsCfg,
discoverer: discoverer,
conns: make(chan IntermediateConnection),
bepProtocolName: bepProtocolName,
tlsDefaultCommonName: tlsDefaultCommonName,
lans: lans,
natService: nat.NewService(myID, cfg),
listenersMut: sync.NewRWMutex(),
listeners: make(map[string]genericListener),
listenerTokens: make(map[string]suture.ServiceToken),
curConMut: sync.NewMutex(),
currentConnection: make(map[protocol.DeviceID]Connection),
}
cfg.Subscribe(service)
// The rate variables are in KiB/s in the UI (despite the camel casing
// of the name). We multiply by 1024 here to get B/s.
if service.cfg.Options().MaxSendKbps > 0 {
service.writeRateLimit = ratelimit.NewBucketWithRate(float64(1024*service.cfg.Options().MaxSendKbps), int64(5*1024*service.cfg.Options().MaxSendKbps))
}
if service.cfg.Options().MaxRecvKbps > 0 {
service.readRateLimit = ratelimit.NewBucketWithRate(float64(1024*service.cfg.Options().MaxRecvKbps), int64(5*1024*service.cfg.Options().MaxRecvKbps))
}
// There are several moving parts here; one routine per listening address
// (handled in configuration changing) to handle incoming connections,
// one routine to periodically attempt outgoing connections, one routine to
// the the common handling regardless of whether the connection was
// incoming or outgoing.
service.Add(serviceFunc(service.connect))
service.Add(serviceFunc(service.handle))
raw := cfg.Raw()
// Actually starts the listeners and NAT service
service.CommitConfiguration(raw, raw)
return service
}
var (
errDisabled = errors.New("disabled by configuration")
)
func (s *Service) handle() {
next:
for c := range s.conns {
cs := c.ConnectionState()
// We should have negotiated the next level protocol "bep/1.0" as part
// of the TLS handshake. Unfortunately this can't be a hard error,
// because there are implementations out there that don't support
// protocol negotiation (iOS for one...).
if !cs.NegotiatedProtocolIsMutual || cs.NegotiatedProtocol != s.bepProtocolName {
l.Infof("Peer %s did not negotiate bep/1.0", c.RemoteAddr())
}
// We should have received exactly one certificate from the other
// side. If we didn't, they don't have a device ID and we drop the
// connection.
certs := cs.PeerCertificates
if cl := len(certs); cl != 1 {
l.Infof("Got peer certificate list of length %d != 1 from %s; protocol error", cl, c.RemoteAddr())
c.Close()
continue
}
remoteCert := certs[0]
remoteID := protocol.NewDeviceID(remoteCert.Raw)
// The device ID should not be that of ourselves. It can happen
// though, especially in the presence of NAT hairpinning, multiple
// clients between the same NAT gateway, and global discovery.
if remoteID == s.myID {
l.Infof("Connected to myself (%s) - should not happen", remoteID)
c.Close()
continue
}
hello, err := exchangeHello(c, s.model.GetHello(remoteID))
if err != nil {
l.Infof("Failed to exchange Hello messages with %s (%s): %s", remoteID, c.RemoteAddr(), err)
c.Close()
continue
}
s.model.OnHello(remoteID, c.RemoteAddr(), hello)
// If we have a relay connection, and the new incoming connection is
// not a relay connection, we should drop that, and prefer the this one.
s.curConMut.Lock()
ct, ok := s.currentConnection[remoteID]
s.curConMut.Unlock()
// Lower priority is better, just like nice etc.
if ok && ct.Priority > c.Priority {
l.Debugln("Switching connections", remoteID)
s.model.Close(remoteID, protocol.ErrSwitchingConnections)
} else if s.model.ConnectedTo(remoteID) {
// We should not already be connected to the other party. TODO: This
// could use some better handling. If the old connection is dead but
// hasn't timed out yet we may want to drop *that* connection and keep
// this one. But in case we are two devices connecting to each other
// in parallel we don't want to do that or we end up with no
// connections still established...
l.Infof("Connected to already connected device (%s)", remoteID)
c.Close()
continue
} else if s.model.IsPaused(remoteID) {
l.Infof("Connection from paused device (%s)", remoteID)
c.Close()
continue
}
for deviceID, deviceCfg := range s.cfg.Devices() {
if deviceID == remoteID {
// Verify the name on the certificate. By default we set it to
// "syncthing" when generating, but the user may have replaced
// the certificate and used another name.
certName := deviceCfg.CertName
if certName == "" {
certName = s.tlsDefaultCommonName
}
err := remoteCert.VerifyHostname(certName)
if err != nil {
// Incorrect certificate name is something the user most
// likely wants to know about, since it's an advanced
// config. Warn instead of Info.
l.Warnf("Bad certificate from %s (%v): %v", remoteID, c.RemoteAddr(), err)
c.Close()
continue next
}
// If rate limiting is set, and based on the address we should
// limit the connection, then we wrap it in a limiter.
limit := s.shouldLimit(c.RemoteAddr())
wr := io.Writer(c)
if limit && s.writeRateLimit != nil {
wr = NewWriteLimiter(c, s.writeRateLimit)
}
rd := io.Reader(c)
if limit && s.readRateLimit != nil {
rd = NewReadLimiter(c, s.readRateLimit)
}
name := fmt.Sprintf("%s-%s (%s)", c.LocalAddr(), c.RemoteAddr(), c.Type)
protoConn := protocol.NewConnection(remoteID, rd, wr, s.model, name, deviceCfg.Compression)
modelConn := Connection{c, protoConn}
l.Infof("Established secure connection to %s at %s", remoteID, name)
l.Debugf("cipher suite: %04X in lan: %t", c.ConnectionState().CipherSuite, !limit)
s.model.AddConnection(modelConn, hello)
s.curConMut.Lock()
s.currentConnection[remoteID] = modelConn
s.curConMut.Unlock()
continue next
}
}
l.Infof("Connection from %s (%s) with ignored device ID %s", c.RemoteAddr(), c.Type, remoteID)
c.Close()
}
}
func (s *Service) connect() {
nextDial := make(map[string]time.Time)
// Used as delay for the first few connection attempts, increases
// exponentially
initialRampup := time.Second
// Calculated from actual dialers reconnectInterval
var sleep time.Duration
for {
cfg := s.cfg.Raw()
bestDialerPrio := 1<<31 - 1 // worse prio won't build on 32 bit
for _, df := range dialers {
if !df.Enabled(cfg) {
continue
}
if prio := df.Priority(); prio < bestDialerPrio {
bestDialerPrio = prio
}
}
l.Debugln("Reconnect loop")
now := time.Now()
var seen []string
nextDevice:
for _, deviceCfg := range cfg.Devices {
deviceID := deviceCfg.DeviceID
if deviceID == s.myID {
continue
}
paused := s.model.IsPaused(deviceID)
if paused {
continue
}
connected := s.model.ConnectedTo(deviceID)
s.curConMut.Lock()
ct := s.currentConnection[deviceID]
s.curConMut.Unlock()
if connected && ct.Priority == bestDialerPrio {
// Things are already as good as they can get.
continue
}
l.Debugln("Reconnect loop for", deviceID)
var addrs []string
for _, addr := range deviceCfg.Addresses {
if addr == "dynamic" {
if s.discoverer != nil {
if t, err := s.discoverer.Lookup(deviceID); err == nil {
addrs = append(addrs, t...)
}
}
} else {
addrs = append(addrs, addr)
}
}
seen = append(seen, addrs...)
for _, addr := range addrs {
nextDialAt, ok := nextDial[addr]
if ok && initialRampup >= sleep && nextDialAt.After(now) {
l.Debugf("Not dialing %v as sleep is %v, next dial is at %s and current time is %s", addr, sleep, nextDialAt, now)
continue
}
// If we fail at any step before actually getting the dialer
// retry in a minute
nextDial[addr] = now.Add(time.Minute)
uri, err := url.Parse(addr)
if err != nil {
l.Infof("Dialer for %s: %v", addr, err)
continue
}
dialerFactory, err := s.getDialerFactory(cfg, uri)
if err == errDisabled {
l.Debugln("Dialer for", uri, "is disabled")
continue
}
if err != nil {
l.Infof("Dialer for %v: %v", uri, err)
continue
}
if connected && dialerFactory.Priority() >= ct.Priority {
l.Debugf("Not dialing using %s as priorty is less than current connection (%d >= %d)", dialerFactory, dialerFactory.Priority(), ct.Priority)
continue
}
dialer := dialerFactory.New(s.cfg, s.tlsCfg)
l.Debugln("dial", deviceCfg.DeviceID, uri)
nextDial[addr] = now.Add(dialer.RedialFrequency())
conn, err := dialer.Dial(deviceID, uri)
if err != nil {
l.Debugln("dial failed", deviceCfg.DeviceID, uri, err)
continue
}
if connected {
s.model.Close(deviceID, protocol.ErrSwitchingConnections)
}
s.conns <- conn
continue nextDevice
}
}
nextDial, sleep = filterAndFindSleepDuration(nextDial, seen, now)
if initialRampup < sleep {
l.Debugln("initial rampup; sleep", initialRampup, "and update to", initialRampup*2)
time.Sleep(initialRampup)
initialRampup *= 2
} else {
l.Debugln("sleep until next dial", sleep)
time.Sleep(sleep)
}
}
}
func (s *Service) shouldLimit(addr net.Addr) bool {
if s.cfg.Options().LimitBandwidthInLan {
return true
}
tcpaddr, ok := addr.(*net.TCPAddr)
if !ok {
return true
}
for _, lan := range s.lans {
if lan.Contains(tcpaddr.IP) {
return false
}
}
return !tcpaddr.IP.IsLoopback()
}
func (s *Service) createListener(factory listenerFactory, uri *url.URL) bool {
// must be called with listenerMut held
l.Debugln("Starting listener", uri)
listener := factory.New(uri, s.cfg, s.tlsCfg, s.conns, s.natService)
listener.OnAddressesChanged(s.logListenAddressesChangedEvent)
s.listeners[uri.String()] = listener
s.listenerTokens[uri.String()] = s.Add(listener)
return true
}
func (s *Service) logListenAddressesChangedEvent(l genericListener) {
events.Default.Log(events.ListenAddressesChanged, map[string]interface{}{
"address": l.URI(),
"lan": l.LANAddresses(),
"wan": l.WANAddresses(),
})
}
func (s *Service) VerifyConfiguration(from, to config.Configuration) error {
return nil
}
func (s *Service) CommitConfiguration(from, to config.Configuration) bool {
// We require a restart if a device as been removed.
restart := false
newDevices := make(map[protocol.DeviceID]bool, len(to.Devices))
for _, dev := range to.Devices {
newDevices[dev.DeviceID] = true
}
for _, dev := range from.Devices {
if !newDevices[dev.DeviceID] {
restart = true
}
}
s.listenersMut.Lock()
seen := make(map[string]struct{})
for _, addr := range config.Wrap("", to).ListenAddresses() {
if _, ok := s.listeners[addr]; ok {
seen[addr] = struct{}{}
continue
}
uri, err := url.Parse(addr)
if err != nil {
l.Infof("Listener for %s: %v", addr, err)
continue
}
factory, err := s.getListenerFactory(to, uri)
if err == errDisabled {
l.Debugln("Listener for", uri, "is disabled")
continue
}
if err != nil {
l.Infof("Listener for %v: %v", uri, err)
continue
}
s.createListener(factory, uri)
seen[addr] = struct{}{}
}
for addr, listener := range s.listeners {
if _, ok := seen[addr]; !ok || !listener.Factory().Enabled(to) {
l.Debugln("Stopping listener", addr)
s.Remove(s.listenerTokens[addr])
delete(s.listenerTokens, addr)
delete(s.listeners, addr)
}
}
s.listenersMut.Unlock()
if to.Options.NATEnabled && s.natServiceToken == nil {
l.Debugln("Starting NAT service")
token := s.Add(s.natService)
s.natServiceToken = &token
} else if !to.Options.NATEnabled && s.natServiceToken != nil {
l.Debugln("Stopping NAT service")
s.Remove(*s.natServiceToken)
s.natServiceToken = nil
}
return !restart
}
func (s *Service) AllAddresses() []string {
s.listenersMut.RLock()
var addrs []string
for _, listener := range s.listeners {
for _, lanAddr := range listener.LANAddresses() {
addrs = append(addrs, lanAddr.String())
}
for _, wanAddr := range listener.WANAddresses() {
addrs = append(addrs, wanAddr.String())
}
}
s.listenersMut.RUnlock()
return util.UniqueStrings(addrs)
}
func (s *Service) ExternalAddresses() []string {
s.listenersMut.RLock()
var addrs []string
for _, listener := range s.listeners {
for _, wanAddr := range listener.WANAddresses() {
addrs = append(addrs, wanAddr.String())
}
}
s.listenersMut.RUnlock()
return util.UniqueStrings(addrs)
}
func (s *Service) Status() map[string]interface{} {
s.listenersMut.RLock()
result := make(map[string]interface{})
for addr, listener := range s.listeners {
status := make(map[string]interface{})
err := listener.Error()
if err != nil {
status["error"] = err.Error()
}
status["lanAddresses"] = urlsToStrings(listener.LANAddresses())
status["wanAddresses"] = urlsToStrings(listener.WANAddresses())
result[addr] = status
}
s.listenersMut.RUnlock()
return result
}
func (s *Service) getDialerFactory(cfg config.Configuration, uri *url.URL) (dialerFactory, error) {
dialerFactory, ok := dialers[uri.Scheme]
if !ok {
return nil, fmt.Errorf("unknown address scheme %q", uri.Scheme)
}
if !dialerFactory.Enabled(cfg) {
return nil, errDisabled
}
return dialerFactory, nil
}
func (s *Service) getListenerFactory(cfg config.Configuration, uri *url.URL) (listenerFactory, error) {
listenerFactory, ok := listeners[uri.Scheme]
if !ok {
return nil, fmt.Errorf("unknown address scheme %q", uri.Scheme)
}
if !listenerFactory.Enabled(cfg) {
return nil, errDisabled
}
return listenerFactory, nil
}
func exchangeHello(c net.Conn, h protocol.HelloMessage) (protocol.HelloMessage, error) {
if err := c.SetDeadline(time.Now().Add(2 * time.Second)); err != nil {
return protocol.HelloMessage{}, err
}
defer c.SetDeadline(time.Time{})
header := make([]byte, 8)
msg := h.MustMarshalXDR()
binary.BigEndian.PutUint32(header[:4], protocol.HelloMessageMagic)
binary.BigEndian.PutUint32(header[4:], uint32(len(msg)))
if _, err := c.Write(header); err != nil {
return protocol.HelloMessage{}, err
}
if _, err := c.Write(msg); err != nil {
return protocol.HelloMessage{}, err
}
if _, err := io.ReadFull(c, header); err != nil {
return protocol.HelloMessage{}, err
}
if binary.BigEndian.Uint32(header[:4]) != protocol.HelloMessageMagic {
return protocol.HelloMessage{}, fmt.Errorf("incorrect magic")
}
msgSize := binary.BigEndian.Uint32(header[4:])
if msgSize > 1024 {
return protocol.HelloMessage{}, fmt.Errorf("hello message too big")
}
buf := make([]byte, msgSize)
var hello protocol.HelloMessage
if _, err := io.ReadFull(c, buf); err != nil {
return protocol.HelloMessage{}, err
}
if err := hello.UnmarshalXDR(buf); err != nil {
return protocol.HelloMessage{}, err
}
return hello, nil
}
func filterAndFindSleepDuration(nextDial map[string]time.Time, seen []string, now time.Time) (map[string]time.Time, time.Duration) {
newNextDial := make(map[string]time.Time)
for _, addr := range seen {
nextDialAt, ok := nextDial[addr]
if ok {
newNextDial[addr] = nextDialAt
}
}
min := time.Minute
for _, next := range newNextDial {
cur := next.Sub(now)
if cur < min {
min = cur
}
}
return newNextDial, min
}
func urlsToStrings(urls []*url.URL) []string {
strings := make([]string, len(urls))
for i, url := range urls {
strings[i] = url.String()
}
return strings
}