Adds support HomeKit cameras!

pkg/srtp/server.go

@@ -0,0 +1,61 @@
+package srtp
+
+import (
+	"encoding/binary"
+	"net"
+)
+
+// Server using same UDP port for SRTP and for SRTCP as the iPhone does
+// this is not really necessary but anyway
+type Server struct {
+	sessions map[uint32]*Session
+}
+
+func (s *Server) AddSession(session *Session) {
+	if s.sessions == nil {
+		s.sessions = map[uint32]*Session{}
+	}
+	s.sessions[session.RemoteSSRC] = session
+}
+
+func (s *Server) RemoveSession(session *Session) {
+	delete(s.sessions, session.RemoteSSRC)
+}
+
+func (s *Server) Serve(conn net.PacketConn) error {
+	buf := make([]byte, 2048)
+	for {
+		n, addr, err := conn.ReadFrom(buf)
+		if err != nil {
+			return err
+		}
+
+		// Multiplexing RTP Data and Control Packets on a Single Port
+		// https://datatracker.ietf.org/doc/html/rfc5761
+
+		// this is default position for SSRC in RTP packet
+		ssrc := binary.BigEndian.Uint32(buf[8:])
+		session, ok := s.sessions[ssrc]
+		if ok {
+			if session.Write == nil {
+				session.Write = func(b []byte) (int, error) {
+					return conn.WriteTo(b, addr)
+				}
+			}
+
+			if err = session.HandleRTP(buf[:n]); err != nil {
+				return err
+			}
+		} else {
+			// this is default position for SSRC in RTCP packet
+			ssrc = binary.BigEndian.Uint32(buf[4:])
+			if session, ok = s.sessions[ssrc]; !ok {
+				continue // skip unknown ssrc
+			}
+
+			if err = session.HandleRTCP(buf[:n]); err != nil {
+				return err
+			}
+		}
+	}
+}