Major Refactoring and code restructuring for a cleaner API

RTPRelay.go

@@ -0,0 +1,106 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/hex"
+	"io"
+	"log"
+	"net"
+)
+
+// RTPRelay holds information on the relaying stream listener
+type RTPRelay struct {
+	close      bool
+	targetIP   net.IP
+	targetPort int
+}
+
+// CreateRTPRelay creates a UDP listener that handles live data
+// from the camera and forwards it as an RTP stream
+func CreateRTPRelay(targetAddress net.IP, targetPort int) RTPRelay {
+	conn, err := net.ListenPacket("udp", ":6669")
+
+	if err != nil {
+		log.Printf("ERROR: %s\n", err)
+	}
+
+	relay := RTPRelay{
+		targetIP:   targetAddress,
+		targetPort: targetPort,
+	}
+	if err != nil {
+		log.Printf("ERROR: %s\n", err)
+	}
+
+	go handleCameraStream(relay, conn)
+
+	return relay
+}
+
+func handleCameraStream(relay RTPRelay, conn net.PacketConn) {
+	buffer := make([]byte, 2048)
+	header := StreamHeader{}
+	var payload []byte
+
+	rtpTarget := net.UDPAddr{
+		IP:   relay.targetIP,
+		Port: relay.targetPort,
+	}
+	rtpSource, _ := net.ResolveUDPAddr("udp", "127.0.0.1:5000")
+	rtpConn, _ := net.DialUDP("udp", rtpSource, &rtpTarget)
+
+	var sequenceNumber uint16
+	var elapsed uint32
+
+	frameBuffer := []byte{}
+
+	for {
+		conn.ReadFrom(buffer)
+		packetReader := bytes.NewReader(buffer)
+		binary.Read(packetReader, binary.BigEndian, &header)
+
+		if header.Magic != 0xBCDE {
+			log.Printf("Received message with invalid magic (%x).", header.Magic)
+			break
+		}
+		if header.Length > 0 {
+			payload = make([]byte, header.Length)
+			bytesRead, err := io.ReadFull(packetReader, payload)
+			if err != nil {
+				log.Printf("Read Error: %s, %d bytes\n", err, bytesRead)
+				break
+			}
+		} else {
+			payload = []byte{}
+		}
+
+		switch header.MessageType {
+		case 0x0001: // H.264 Data
+			frameBuffer = append(frameBuffer, payload...)
+		case 0x0002: // Time
+			packet := bytes.Buffer{}
+			packet.Write([]byte{0x80, 0x63})
+			binary.Write(&packet, binary.BigEndian, sequenceNumber)
+			binary.Write(&packet, binary.BigEndian, (uint32)(elapsed*90))
+			binary.Write(&packet, binary.BigEndian, (uint64(0)))
+			packet.Write(frameBuffer)
+			rtpConn.Write(packet.Bytes())
+			frameBuffer = []byte{}
+			sequenceNumber++
+			elapsed = binary.LittleEndian.Uint32(payload[12:])
+			//log.Printf("Elapsed: %d (%x)\n", elapsed, payload[12:])
+		default:
+			log.Printf("Received Unknown Message: %+v\n", header)
+			log.Printf("Payload:\n%s\n", hex.Dump(payload))
+		}
+		if relay.close {
+			break
+		}
+	}
+}
+
+// Stop stops listening for packets
+func (r *RTPRelay) Stop() {
+	r.close = true
+}