mv internal lib
This commit is contained in:
Jakob Borg
229
lib/beacon/broadcast.go
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229
lib/beacon/broadcast.go
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// 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 beacon
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import (
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"fmt"
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"net"
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"time"
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"github.com/thejerf/suture"
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)
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type Broadcast struct {
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*suture.Supervisor
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port int
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inbox chan []byte
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outbox chan recv
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}
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func NewBroadcast(port int) *Broadcast {
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b := &Broadcast{
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Supervisor: suture.New("broadcastBeacon", suture.Spec{
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// Don't retry too frenetically: an error to open a socket or
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// whatever is usually something that is either permanent or takes
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// a while to get solved...
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FailureThreshold: 2,
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FailureBackoff: 60 * time.Second,
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// Only log restarts in debug mode.
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Log: func(line string) {
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if debug {
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l.Debugln(line)
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}
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},
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}),
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port: port,
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inbox: make(chan []byte),
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outbox: make(chan recv, 16),
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}
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b.Add(&broadcastReader{
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port: port,
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outbox: b.outbox,
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})
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b.Add(&broadcastWriter{
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port: port,
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inbox: b.inbox,
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})
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return b
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}
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func (b *Broadcast) Send(data []byte) {
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b.inbox <- data
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}
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func (b *Broadcast) Recv() ([]byte, net.Addr) {
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recv := <-b.outbox
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return recv.data, recv.src
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}
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type broadcastWriter struct {
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port int
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inbox chan []byte
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conn *net.UDPConn
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failed bool // Have we already logged a failure reason?
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}
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func (w *broadcastWriter) Serve() {
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if debug {
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l.Debugln(w, "starting")
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defer l.Debugln(w, "stopping")
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}
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var err error
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w.conn, err = net.ListenUDP("udp4", nil)
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if err != nil {
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if !w.failed {
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l.Warnln("Local discovery over IPv4 unavailable:", err)
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w.failed = true
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}
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return
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}
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defer w.conn.Close()
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w.failed = false
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for bs := range w.inbox {
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addrs, err := net.InterfaceAddrs()
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if err != nil {
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if debug {
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l.Debugln("Local discovery (broadcast writer):", err)
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}
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continue
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}
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var dsts []net.IP
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for _, addr := range addrs {
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if iaddr, ok := addr.(*net.IPNet); ok && len(iaddr.IP) >= 4 && iaddr.IP.IsGlobalUnicast() && iaddr.IP.To4() != nil {
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baddr := bcast(iaddr)
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dsts = append(dsts, baddr.IP)
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}
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}
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if len(dsts) == 0 {
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// Fall back to the general IPv4 broadcast address
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dsts = append(dsts, net.IP{0xff, 0xff, 0xff, 0xff})
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}
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if debug {
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l.Debugln("addresses:", dsts)
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}
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for _, ip := range dsts {
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dst := &net.UDPAddr{IP: ip, Port: w.port}
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w.conn.SetWriteDeadline(time.Now().Add(10 * time.Second))
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_, err := w.conn.WriteTo(bs, dst)
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if err, ok := err.(net.Error); ok && err.Timeout() {
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// Write timeouts should not happen. We treat it as a fatal
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// error on the socket.
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l.Infoln("Local discovery (broadcast writer):", err)
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w.failed = true
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return
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} else if err, ok := err.(net.Error); ok && err.Temporary() {
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// A transient error. Lets hope for better luck in the future.
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if debug {
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l.Debugln(err)
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}
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continue
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} else if err != nil {
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// Some other error that we don't expect. Bail and retry.
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l.Infoln("Local discovery (broadcast writer):", err)
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w.failed = true
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return
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} else if debug {
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l.Debugf("sent %d bytes to %s", len(bs), dst)
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}
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}
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}
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}
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func (w *broadcastWriter) Stop() {
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w.conn.Close()
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}
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func (w *broadcastWriter) String() string {
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return fmt.Sprintf("broadcastWriter@%p", w)
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}
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type broadcastReader struct {
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port int
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outbox chan recv
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conn *net.UDPConn
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failed bool
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}
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func (r *broadcastReader) Serve() {
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if debug {
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l.Debugln(r, "starting")
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defer l.Debugln(r, "stopping")
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}
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var err error
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r.conn, err = net.ListenUDP("udp4", &net.UDPAddr{Port: r.port})
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if err != nil {
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if !r.failed {
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l.Warnln("Local discovery over IPv4 unavailable:", err)
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r.failed = true
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}
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return
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}
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defer r.conn.Close()
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bs := make([]byte, 65536)
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for {
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n, addr, err := r.conn.ReadFrom(bs)
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if err != nil {
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if !r.failed {
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l.Infoln("Local discovery (broadcast reader):", err)
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r.failed = true
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}
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return
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}
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r.failed = false
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if debug {
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l.Debugf("recv %d bytes from %s", n, addr)
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}
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c := make([]byte, n)
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copy(c, bs)
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select {
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case r.outbox <- recv{c, addr}:
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default:
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if debug {
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l.Debugln("dropping message")
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}
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}
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}
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}
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func (r *broadcastReader) Stop() {
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r.conn.Close()
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}
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func (r *broadcastReader) String() string {
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return fmt.Sprintf("broadcastReader@%p", r)
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}
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func bcast(ip *net.IPNet) *net.IPNet {
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var bc = &net.IPNet{}
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bc.IP = make([]byte, len(ip.IP))
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copy(bc.IP, ip.IP)
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bc.Mask = ip.Mask
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offset := len(bc.IP) - len(bc.Mask)
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for i := range bc.IP {
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if i-offset >= 0 {
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bc.IP[i] = ip.IP[i] | ^ip.Mask[i-offset]
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}
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}
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return bc
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}
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