Implement IPv6 multicast again (fixes #346)

beacon/beacon.go

@@ -0,0 +1,46 @@
+// Copyright (C) 2014 Jakob Borg and Contributors (see the CONTRIBUTORS file).
+// All rights reserved. Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package beacon
+
+import "net"
+
+type recv struct {
+	data []byte
+	src  net.Addr
+}
+
+type dst struct {
+	intf string
+	conn *net.UDPConn
+}
+
+type Interface interface {
+	Send(data []byte)
+	Recv() ([]byte, net.Addr)
+}
+
+func genericReader(conn *net.UDPConn, outbox chan<- recv) {
+	bs := make([]byte, 65536)
+	for {
+		n, addr, err := conn.ReadFrom(bs)
+		if err != nil {
+			l.Warnln("multicast read:", err)
+			return
+		}
+		if debug {
+			l.Debugf("recv %d bytes from %s", n, addr)
+		}
+
+		c := make([]byte, n)
+		copy(c, bs)
+		select {
+		case outbox <- recv{c, addr}:
+		default:
+			if debug {
+				l.Debugln("dropping message")
+			}
+		}
+	}
+}