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local.go
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local.go
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// Copyright (C) 2014 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 discover
import (
"bytes"
"encoding/hex"
"io"
"net"
"net/url"
"strconv"
"time"
"github.com/syncthing/syncthing/lib/beacon"
"github.com/syncthing/syncthing/lib/events"
"github.com/syncthing/syncthing/lib/protocol"
"github.com/thejerf/suture"
)
type localClient struct {
*suture.Supervisor
myID protocol.DeviceID
addrList AddressLister
name string
beacon beacon.Interface
localBcastStart time.Time
localBcastTick <-chan time.Time
forcedBcastTick chan time.Time
*cache
}
const (
BroadcastInterval = 30 * time.Second
CacheLifeTime = 3 * BroadcastInterval
)
func NewLocal(id protocol.DeviceID, addr string, addrList AddressLister) (FinderService, error) {
c := &localClient{
Supervisor: suture.NewSimple("local"),
myID: id,
addrList: addrList,
localBcastTick: time.Tick(BroadcastInterval),
forcedBcastTick: make(chan time.Time),
localBcastStart: time.Now(),
cache: newCache(),
}
host, port, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
if len(host) == 0 {
// A broadcast client
c.name = "IPv4 local"
bcPort, err := strconv.Atoi(port)
if err != nil {
return nil, err
}
c.startLocalIPv4Broadcasts(bcPort)
} else {
// A multicast client
c.name = "IPv6 local"
c.startLocalIPv6Multicasts(addr)
}
go c.sendLocalAnnouncements()
return c, nil
}
func (c *localClient) startLocalIPv4Broadcasts(localPort int) {
c.beacon = beacon.NewBroadcast(localPort)
c.Add(c.beacon)
go c.recvAnnouncements(c.beacon)
}
func (c *localClient) startLocalIPv6Multicasts(localMCAddr string) {
c.beacon = beacon.NewMulticast(localMCAddr)
c.Add(c.beacon)
go c.recvAnnouncements(c.beacon)
}
// Lookup returns a list of addresses the device is available at.
func (c *localClient) Lookup(device protocol.DeviceID) (addresses []string, err error) {
if cache, ok := c.Get(device); ok {
if time.Since(cache.when) < CacheLifeTime {
addresses = cache.Addresses
}
}
return
}
func (c *localClient) String() string {
return c.name
}
func (c *localClient) Error() error {
return c.beacon.Error()
}
func (c *localClient) announcementPkt() Announce {
var addrs []Address
for _, addr := range c.addrList.AllAddresses() {
addrs = append(addrs, Address{
URL: addr,
})
}
return Announce{
Magic: AnnouncementMagic,
This: Device{
ID: c.myID[:],
Addresses: addrs,
},
}
}
func (c *localClient) sendLocalAnnouncements() {
var pkt = c.announcementPkt()
msg := pkt.MustMarshalXDR()
for {
c.beacon.Send(msg)
select {
case <-c.localBcastTick:
case <-c.forcedBcastTick:
}
}
}
func (c *localClient) recvAnnouncements(b beacon.Interface) {
for {
buf, addr := b.Recv()
var pkt Announce
err := pkt.UnmarshalXDR(buf)
if err != nil && err != io.EOF {
l.Debugf("discover: Failed to unmarshal local announcement from %s:\n%s", addr, hex.Dump(buf))
continue
}
if pkt.Magic != AnnouncementMagic {
l.Debugf("discover: Incorrect magic from %s: %s != %s", addr, pkt.Magic, AnnouncementMagic)
continue
}
l.Debugf("discover: Received local announcement from %s for %s", addr, protocol.DeviceIDFromBytes(pkt.This.ID))
var newDevice bool
if !bytes.Equal(pkt.This.ID, c.myID[:]) {
newDevice = c.registerDevice(addr, pkt.This)
}
if newDevice {
// Force a transmit to announce ourselves, if we are ready to do
// so right away.
select {
case c.forcedBcastTick <- time.Now():
default:
}
}
}
}
func (c *localClient) registerDevice(src net.Addr, device Device) bool {
var id protocol.DeviceID
copy(id[:], device.ID)
// Remember whether we already had a valid cache entry for this device.
ce, existsAlready := c.Get(id)
isNewDevice := !existsAlready || time.Since(ce.when) > CacheLifeTime
// Any empty or unspecified addresses should be set to the source address
// of the announcement. We also skip any addresses we can't parse.
l.Debugln("discover: Registering addresses for", id)
var validAddresses []string
for _, addr := range device.Addresses {
u, err := url.Parse(addr.URL)
if err != nil {
continue
}
tcpAddr, err := net.ResolveTCPAddr("tcp", u.Host)
if err != nil {
continue
}
if len(tcpAddr.IP) == 0 || tcpAddr.IP.IsUnspecified() {
host, _, err := net.SplitHostPort(src.String())
if err != nil {
continue
}
u.Host = net.JoinHostPort(host, strconv.Itoa(tcpAddr.Port))
l.Debugf("discover: Reconstructed URL is %#v", u)
validAddresses = append(validAddresses, u.String())
l.Debugf("discover: Replaced address %v in %s to get %s", tcpAddr.IP, addr.URL, u.String())
} else {
validAddresses = append(validAddresses, addr.URL)
l.Debugf("discover: Accepted address %s verbatim", addr.URL)
}
}
c.Set(id, CacheEntry{
Addresses: validAddresses,
when: time.Now(),
found: true,
})
if isNewDevice {
events.Default.Log(events.DeviceDiscovered, map[string]interface{}{
"device": id.String(),
"addrs": validAddresses,
})
}
return isNewDevice
}