109 lines
2.4 KiB
Go
109 lines
2.4 KiB
Go
// Copyright (C) 2014 The Syncthing Authors.
|
|
//
|
|
// This program is free software: you can redistribute it and/or modify it
|
|
// under the terms of the GNU General Public License as published by the Free
|
|
// Software Foundation, either version 3 of the License, or (at your option)
|
|
// any later version.
|
|
//
|
|
// This program is distributed in the hope that it will be useful, but WITHOUT
|
|
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
// more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License along
|
|
// with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
package beacon
|
|
|
|
import "net"
|
|
|
|
type Broadcast struct {
|
|
conn *net.UDPConn
|
|
port int
|
|
inbox chan []byte
|
|
outbox chan recv
|
|
}
|
|
|
|
func NewBroadcast(port int) (*Broadcast, error) {
|
|
conn, err := net.ListenUDP("udp", &net.UDPAddr{Port: port})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
b := &Broadcast{
|
|
conn: conn,
|
|
port: port,
|
|
inbox: make(chan []byte),
|
|
outbox: make(chan recv, 16),
|
|
}
|
|
|
|
go genericReader(b.conn, b.outbox)
|
|
go b.writer()
|
|
|
|
return b, nil
|
|
}
|
|
|
|
func (b *Broadcast) Send(data []byte) {
|
|
b.inbox <- data
|
|
}
|
|
|
|
func (b *Broadcast) Recv() ([]byte, net.Addr) {
|
|
recv := <-b.outbox
|
|
return recv.data, recv.src
|
|
}
|
|
|
|
func (b *Broadcast) writer() {
|
|
for bs := range b.inbox {
|
|
|
|
addrs, err := net.InterfaceAddrs()
|
|
if err != nil {
|
|
l.Warnln("Broadcast: interface addresses:", err)
|
|
continue
|
|
}
|
|
|
|
var dsts []net.IP
|
|
for _, addr := range addrs {
|
|
if iaddr, ok := addr.(*net.IPNet); ok && len(iaddr.IP) >= 4 && iaddr.IP.IsGlobalUnicast() && iaddr.IP.To4() != nil {
|
|
baddr := bcast(iaddr)
|
|
dsts = append(dsts, baddr.IP)
|
|
}
|
|
}
|
|
|
|
if len(dsts) == 0 {
|
|
// Fall back to the general IPv4 broadcast address
|
|
dsts = append(dsts, net.IP{0xff, 0xff, 0xff, 0xff})
|
|
}
|
|
|
|
if debug {
|
|
l.Debugln("addresses:", dsts)
|
|
}
|
|
|
|
for _, ip := range dsts {
|
|
dst := &net.UDPAddr{IP: ip, Port: b.port}
|
|
|
|
_, err := b.conn.WriteTo(bs, dst)
|
|
if err != nil {
|
|
if debug {
|
|
l.Debugln(err)
|
|
}
|
|
} else if debug {
|
|
l.Debugf("sent %d bytes to %s", len(bs), dst)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
func bcast(ip *net.IPNet) *net.IPNet {
|
|
var bc = &net.IPNet{}
|
|
bc.IP = make([]byte, len(ip.IP))
|
|
copy(bc.IP, ip.IP)
|
|
bc.Mask = ip.Mask
|
|
|
|
offset := len(bc.IP) - len(bc.Mask)
|
|
for i := range bc.IP {
|
|
if i-offset >= 0 {
|
|
bc.IP[i] = ip.IP[i] | ^ip.Mask[i-offset]
|
|
}
|
|
}
|
|
return bc
|
|
}
|