568 lines
13 KiB
Go
568 lines
13 KiB
Go
// Copyright (C) 2014 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 discover
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import (
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"bytes"
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"encoding/hex"
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"errors"
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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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"runtime"
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"sort"
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"time"
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"github.com/syncthing/protocol"
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"github.com/syncthing/syncthing/lib/beacon"
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"github.com/syncthing/syncthing/lib/events"
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"github.com/syncthing/syncthing/lib/osutil"
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"github.com/syncthing/syncthing/lib/relay"
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"github.com/syncthing/syncthing/lib/sync"
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)
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type Discoverer struct {
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myID protocol.DeviceID
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listenAddrs []string
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relaySvc *relay.Svc
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localBcastIntv time.Duration
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localBcastStart time.Time
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cacheLifetime time.Duration
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negCacheCutoff time.Duration
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beacons []beacon.Interface
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extPort uint16
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localBcastTick <-chan time.Time
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forcedBcastTick chan time.Time
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registryLock sync.RWMutex
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addressRegistry map[protocol.DeviceID][]CacheEntry
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relayRegistry map[protocol.DeviceID][]CacheEntry
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lastLookup map[protocol.DeviceID]time.Time
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clients []Client
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mut sync.RWMutex
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}
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type CacheEntry struct {
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Address string
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Seen time.Time
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}
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var (
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ErrIncorrectMagic = errors.New("incorrect magic number")
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)
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func NewDiscoverer(id protocol.DeviceID, addresses []string, relaySvc *relay.Svc) *Discoverer {
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return &Discoverer{
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myID: id,
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listenAddrs: addresses,
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relaySvc: relaySvc,
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localBcastIntv: 30 * time.Second,
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cacheLifetime: 5 * time.Minute,
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negCacheCutoff: 3 * time.Minute,
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addressRegistry: make(map[protocol.DeviceID][]CacheEntry),
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relayRegistry: make(map[protocol.DeviceID][]CacheEntry),
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lastLookup: make(map[protocol.DeviceID]time.Time),
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registryLock: sync.NewRWMutex(),
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mut: sync.NewRWMutex(),
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}
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}
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func (d *Discoverer) StartLocal(localPort int, localMCAddr string) {
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if localPort > 0 {
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d.startLocalIPv4Broadcasts(localPort)
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}
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if len(localMCAddr) > 0 {
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d.startLocalIPv6Multicasts(localMCAddr)
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}
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if len(d.beacons) == 0 {
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l.Warnln("Local discovery unavailable")
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return
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}
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d.localBcastTick = time.Tick(d.localBcastIntv)
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d.forcedBcastTick = make(chan time.Time)
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d.localBcastStart = time.Now()
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go d.sendLocalAnnouncements()
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}
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func (d *Discoverer) startLocalIPv4Broadcasts(localPort int) {
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bb := beacon.NewBroadcast(localPort)
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d.beacons = append(d.beacons, bb)
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go d.recvAnnouncements(bb)
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bb.ServeBackground()
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}
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func (d *Discoverer) startLocalIPv6Multicasts(localMCAddr string) {
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intfs, err := net.Interfaces()
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if err != nil {
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if debug {
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l.Debugln("discover: interfaces:", err)
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}
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l.Infoln("Local discovery over IPv6 unavailable")
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return
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}
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v6Intfs := 0
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for _, intf := range intfs {
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// Interface flags seem to always be 0 on Windows
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if runtime.GOOS != "windows" && (intf.Flags&net.FlagUp == 0 || intf.Flags&net.FlagMulticast == 0) {
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continue
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}
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mb, err := beacon.NewMulticast(localMCAddr, intf.Name)
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if err != nil {
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if debug {
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l.Debugln("discover: Start local v6:", err)
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}
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continue
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}
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d.beacons = append(d.beacons, mb)
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go d.recvAnnouncements(mb)
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v6Intfs++
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}
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if v6Intfs == 0 {
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l.Infoln("Local discovery over IPv6 unavailable")
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}
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}
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func (d *Discoverer) StartGlobal(servers []string, extPort uint16) {
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d.mut.Lock()
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defer d.mut.Unlock()
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if len(d.clients) > 0 {
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d.stopGlobal()
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}
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d.extPort = extPort
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pkt := d.announcementPkt(true)
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wg := sync.NewWaitGroup()
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clients := make(chan Client, len(servers))
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for _, address := range servers {
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wg.Add(1)
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go func(addr string) {
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defer wg.Done()
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client, err := New(addr, pkt)
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if err != nil {
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l.Infoln("Error creating discovery client", addr, err)
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return
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}
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clients <- client
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}(address)
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}
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wg.Wait()
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close(clients)
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for client := range clients {
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d.clients = append(d.clients, client)
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}
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}
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func (d *Discoverer) StopGlobal() {
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d.mut.Lock()
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defer d.mut.Unlock()
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d.stopGlobal()
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}
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func (d *Discoverer) stopGlobal() {
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for _, client := range d.clients {
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client.Stop()
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}
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d.clients = []Client{}
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}
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func (d *Discoverer) ExtAnnounceOK() map[string]bool {
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d.mut.RLock()
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defer d.mut.RUnlock()
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ret := make(map[string]bool)
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for _, client := range d.clients {
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ret[client.Address()] = client.StatusOK()
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}
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return ret
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}
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// Lookup returns a list of addresses the device is available at, as well as
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// a list of relays the device is supposed to be available on sorted by the
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// sum of latencies between this device, and the device in question.
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func (d *Discoverer) Lookup(device protocol.DeviceID) ([]string, []string) {
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d.registryLock.RLock()
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cachedAddresses := d.filterCached(d.addressRegistry[device])
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cachedRelays := d.filterCached(d.relayRegistry[device])
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lastLookup := d.lastLookup[device]
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d.registryLock.RUnlock()
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d.mut.RLock()
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defer d.mut.RUnlock()
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relays := make([]string, len(cachedRelays))
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for i := range cachedRelays {
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relays[i] = cachedRelays[i].Address
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}
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if len(cachedAddresses) > 0 {
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// There are cached address entries.
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addrs := make([]string, len(cachedAddresses))
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for i := range cachedAddresses {
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addrs[i] = cachedAddresses[i].Address
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}
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return addrs, relays
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}
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if time.Since(lastLookup) < d.negCacheCutoff {
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// We have recently tried to lookup this address and failed. Lets
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// chill for a while.
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return nil, relays
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}
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if len(d.clients) != 0 && time.Since(d.localBcastStart) > d.localBcastIntv {
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// Only perform external lookups if we have at least one external
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// server client and one local announcement interval has passed. This is
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// to avoid finding local peers on their remote address at startup.
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results := make(chan Announce, len(d.clients))
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wg := sync.NewWaitGroup()
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for _, client := range d.clients {
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wg.Add(1)
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go func(c Client) {
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defer wg.Done()
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ann, err := c.Lookup(device)
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if err == nil {
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results <- ann
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}
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}(client)
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}
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wg.Wait()
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close(results)
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cachedAddresses := []CacheEntry{}
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availableRelays := []Relay{}
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seenAddresses := make(map[string]struct{})
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seenRelays := make(map[string]struct{})
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now := time.Now()
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var addrs []string
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for result := range results {
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for _, addr := range result.This.Addresses {
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_, ok := seenAddresses[addr]
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if !ok {
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cachedAddresses = append(cachedAddresses, CacheEntry{
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Address: addr,
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Seen: now,
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})
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seenAddresses[addr] = struct{}{}
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addrs = append(addrs, addr)
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}
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}
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for _, relay := range result.This.Relays {
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_, ok := seenRelays[relay.Address]
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if !ok {
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availableRelays = append(availableRelays, relay)
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seenRelays[relay.Address] = struct{}{}
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}
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}
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}
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relays = addressesSortedByLatency(availableRelays)
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cachedRelays := make([]CacheEntry, len(relays))
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for i := range relays {
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cachedRelays[i] = CacheEntry{
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Address: relays[i],
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Seen: now,
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}
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}
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d.registryLock.Lock()
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d.addressRegistry[device] = cachedAddresses
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d.relayRegistry[device] = cachedRelays
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d.lastLookup[device] = time.Now()
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d.registryLock.Unlock()
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return addrs, relays
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}
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return nil, relays
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}
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func (d *Discoverer) Hint(device string, addrs []string) {
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resAddrs := resolveAddrs(addrs)
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var id protocol.DeviceID
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id.UnmarshalText([]byte(device))
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d.registerDevice(nil, Device{
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Addresses: resAddrs,
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ID: id[:],
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})
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}
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func (d *Discoverer) All() map[protocol.DeviceID][]CacheEntry {
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d.registryLock.RLock()
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devices := make(map[protocol.DeviceID][]CacheEntry, len(d.addressRegistry))
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for device, addrs := range d.addressRegistry {
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addrsCopy := make([]CacheEntry, len(addrs))
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copy(addrsCopy, addrs)
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devices[device] = addrsCopy
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}
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d.registryLock.RUnlock()
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return devices
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}
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func (d *Discoverer) announcementPkt(allowExternal bool) *Announce {
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var addrs []string
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if d.extPort != 0 && allowExternal {
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addrs = []string{fmt.Sprintf("tcp://:%d", d.extPort)}
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} else {
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addrs = resolveAddrs(d.listenAddrs)
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}
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relayAddrs := make([]string, 0)
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if d.relaySvc != nil {
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status := d.relaySvc.ClientStatus()
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for uri, ok := range status {
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if ok {
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relayAddrs = append(relayAddrs, uri)
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}
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}
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}
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return &Announce{
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Magic: AnnouncementMagic,
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This: Device{d.myID[:], addrs, measureLatency(relayAddrs)},
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}
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}
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func (d *Discoverer) sendLocalAnnouncements() {
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var pkt = d.announcementPkt(false)
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msg := pkt.MustMarshalXDR()
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for {
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for _, b := range d.beacons {
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b.Send(msg)
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}
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select {
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case <-d.localBcastTick:
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case <-d.forcedBcastTick:
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}
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}
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}
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func (d *Discoverer) recvAnnouncements(b beacon.Interface) {
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for {
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buf, addr := b.Recv()
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var pkt Announce
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err := pkt.UnmarshalXDR(buf)
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if err != nil && err != io.EOF {
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if debug {
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l.Debugf("discover: Failed to unmarshal local announcement from %s:\n%s", addr, hex.Dump(buf))
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}
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continue
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}
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if debug {
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l.Debugf("discover: Received local announcement from %s for %s", addr, protocol.DeviceIDFromBytes(pkt.This.ID))
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}
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var newDevice bool
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if bytes.Compare(pkt.This.ID, d.myID[:]) != 0 {
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newDevice = d.registerDevice(addr, pkt.This)
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}
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if newDevice {
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select {
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case d.forcedBcastTick <- time.Now():
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}
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}
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}
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}
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func (d *Discoverer) registerDevice(addr net.Addr, device Device) bool {
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var id protocol.DeviceID
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copy(id[:], device.ID)
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d.registryLock.Lock()
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defer d.registryLock.Unlock()
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current := d.filterCached(d.addressRegistry[id])
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orig := current
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for _, deviceAddr := range device.Addresses {
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uri, err := url.Parse(deviceAddr)
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if err != nil {
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if debug {
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l.Debugf("discover: Failed to parse address %s: %s", deviceAddr, err)
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}
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continue
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}
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host, port, err := net.SplitHostPort(uri.Host)
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if err != nil {
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if debug {
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l.Debugf("discover: Failed to split address host %s: %s", deviceAddr, err)
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}
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continue
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}
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if host == "" {
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uri.Host = net.JoinHostPort(addr.(*net.UDPAddr).IP.String(), port)
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deviceAddr = uri.String()
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}
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for i := range current {
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if current[i].Address == deviceAddr {
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current[i].Seen = time.Now()
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goto done
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}
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}
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current = append(current, CacheEntry{
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Address: deviceAddr,
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Seen: time.Now(),
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})
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done:
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}
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if debug {
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l.Debugf("discover: Caching %s addresses: %v", id, current)
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}
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d.addressRegistry[id] = current
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if len(current) > len(orig) {
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addrs := make([]string, len(current))
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for i := range current {
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addrs[i] = current[i].Address
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}
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events.Default.Log(events.DeviceDiscovered, map[string]interface{}{
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"device": id.String(),
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"addrs": addrs,
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})
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}
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return len(current) > len(orig)
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}
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func (d *Discoverer) filterCached(c []CacheEntry) []CacheEntry {
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for i := 0; i < len(c); {
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if ago := time.Since(c[i].Seen); ago > d.cacheLifetime {
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if debug {
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l.Debugf("discover: Removing cached entry %s - seen %v ago", c[i].Address, ago)
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}
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c[i] = c[len(c)-1]
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c = c[:len(c)-1]
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} else {
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i++
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}
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}
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return c
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}
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func addrToAddr(addr *net.TCPAddr) string {
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if len(addr.IP) == 0 || addr.IP.IsUnspecified() {
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return fmt.Sprintf(":%d", addr.Port)
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} else if bs := addr.IP.To4(); bs != nil {
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return fmt.Sprintf("%s:%d", bs.String(), addr.Port)
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} else if bs := addr.IP.To16(); bs != nil {
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return fmt.Sprintf("[%s]:%d", bs.String(), addr.Port)
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}
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return ""
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}
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func resolveAddrs(addrs []string) []string {
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var raddrs []string
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for _, addrStr := range addrs {
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uri, err := url.Parse(addrStr)
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if err != nil {
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continue
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}
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addrRes, err := net.ResolveTCPAddr("tcp", uri.Host)
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if err != nil {
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continue
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}
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addr := addrToAddr(addrRes)
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if len(addr) > 0 {
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uri.Host = addr
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raddrs = append(raddrs, uri.String())
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}
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}
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return raddrs
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}
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func measureLatency(relayAdresses []string) []Relay {
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relays := make([]Relay, 0, len(relayAdresses))
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for i, addr := range relayAdresses {
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relay := Relay{
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Address: addr,
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Latency: int32(time.Hour / time.Millisecond),
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}
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relays = append(relays, relay)
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if latency, err := getLatencyForURL(addr); err == nil {
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if debug {
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l.Debugf("Relay %s latency %s", addr, latency)
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}
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relays[i].Latency = int32(latency / time.Millisecond)
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} else {
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l.Debugf("Failed to get relay %s latency %s", addr, err)
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}
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}
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return relays
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}
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// addressesSortedByLatency adds local latency to the relay, and sorts them
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// by sum latency, and returns the addresses.
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func addressesSortedByLatency(input []Relay) []string {
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relays := make([]Relay, len(input))
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copy(relays, input)
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for i, relay := range relays {
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if latency, err := getLatencyForURL(relay.Address); err == nil {
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relays[i].Latency += int32(latency / time.Millisecond)
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} else {
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relays[i].Latency += int32(time.Hour / time.Millisecond)
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}
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}
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sort.Sort(relayList(relays))
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addresses := make([]string, 0, len(relays))
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for _, relay := range relays {
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addresses = append(addresses, relay.Address)
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}
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return addresses
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}
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func getLatencyForURL(addr string) (time.Duration, error) {
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uri, err := url.Parse(addr)
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if err != nil {
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return 0, err
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}
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return osutil.TCPPing(uri.Host)
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}
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type relayList []Relay
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func (l relayList) Len() int {
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return len(l)
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}
|
|
|
|
func (l relayList) Less(a, b int) bool {
|
|
return l[a].Latency < l[b].Latency
|
|
}
|
|
|
|
func (l relayList) Swap(a, b int) {
|
|
l[a], l[b] = l[b], l[a]
|
|
}
|