return 400 in case of errors

rtsp_client.go

@@ -3,6 +3,7 @@ package main
 import (
 	"bufio"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -14,6 +15,12 @@ import (
 	"rtsp-server/rtsp"
 )
 
+var (
+	errTeardown = errors.New("teardown")
+	errPlay     = errors.New("play")
+	errRecord   = errors.New("record")
+)
+
 type rtspClient struct {
 	p        *program
 	nconn    net.Conn
@@ -92,16 +99,133 @@ func (c *rtspClient) run() {
 
 		c.log(req.Method)
 
+		res, err := c.handleRequest(req)
+
+		switch err {
+		// normal response
+		case nil:
+			err = rconn.WriteResponse(res)
+			if err != nil {
+				c.log("ERR: %s", err)
+				return
+			}
+
+		// TEARDOWN, close connection silently
+		case errTeardown:
+			return
+
+		// PLAY: first write response, then set state
+		// otherwise, in case of TCP connections, RTP packets could be written
+		// before the response
+		// then switch to RTP if TCP
+		case errPlay:
+			err = rconn.WriteResponse(res)
+			if err != nil {
+				c.log("ERR: %s", err)
+				return
+			}
+
+			c.log("is receiving (via %s)", c.rtpProto)
+
+			c.p.mutex.Lock()
+			c.state = "PLAY"
+			c.p.mutex.Unlock()
+
+			// when rtp protocol is TCP, the RTSP connection becomes a RTP connection
+			// receive RTP feedback, do not parse it, wait until connection closes
+			if c.rtpProto == "tcp" {
+				buf := make([]byte, 1024)
+				for {
+					_, err := c.nconn.Read(buf)
+					if err != nil {
+						return
+					}
+				}
+			}
+
+		// RECORD: switch to RTP if TCP
+		case errRecord:
+			err = rconn.WriteResponse(res)
+			if err != nil {
+				c.log("ERR: %s", err)
+				return
+			}
+
+			c.p.mutex.Lock()
+			c.state = "RECORD"
+			c.p.mutex.Unlock()
+
+			c.log("is publishing (via %s)", c.rtpProto)
+
+			// when rtp protocol is TCP, the RTSP connection becomes a RTP connection
+			// receive RTP data and parse it
+			if c.rtpProto == "tcp" {
+				packet := make([]byte, 2048)
+				bconn := bufio.NewReader(c.nconn)
+				for {
+					byts, err := bconn.Peek(4)
+					if err != nil {
+						return
+					}
+					bconn.Discard(4)
+
+					if byts[0] != 0x24 {
+						c.log("ERR: wrong magic byte")
+						return
+					}
+
+					if byts[1] != 0x00 {
+						c.log("ERR: wrong channel")
+						return
+					}
+
+					plen := binary.BigEndian.Uint16(byts[2:])
+					if plen > 2048 {
+						c.log("ERR: packet len > 2048")
+						return
+					}
+
+					_, err = io.ReadFull(bconn, packet[:plen])
+					if err != nil {
+						return
+					}
+
+					c.p.handleRtp(packet[:plen])
+				}
+			}
+
+		// error: write and exit
+		default:
+			c.log("ERR: %s", err)
+
+			if cseq, ok := req.Headers["cseq"]; ok {
+				rconn.WriteResponse(&rtsp.Response{
+					StatusCode: 400,
+					Status:     "Bad Request",
+					Headers: map[string]string{
+						"CSeq": cseq,
+					},
+				})
+			} else {
+				rconn.WriteResponse(&rtsp.Response{
+					StatusCode: 400,
+					Status:     "Bad Request",
+				})
+			}
+			return
+		}
+	}
+}
+
+func (c *rtspClient) handleRequest(req *rtsp.Request) (*rtsp.Response, error) {
 	cseq, ok := req.Headers["CSeq"]
 	if !ok {
-			c.log("ERR: cseq missing")
-			return
+		return nil, fmt.Errorf("cseq missing")
 	}
 
 	ur, err := url.Parse(req.Path)
 	if err != nil {
-			c.log("ERR: unable to parse path '%s'", req.Path)
-			return
+		return nil, fmt.Errorf("unable to parse path '%s'", req.Path)
 	}
 
 	switch req.Method {
@@ -109,7 +233,7 @@ func (c *rtspClient) run() {
 		// do not check state, since OPTIONS can be requested
 		// in any state
 
-			err = rconn.WriteResponse(&rtsp.Response{
+		return &rtsp.Response{
 			StatusCode: 200,
 			Status:     "OK",
 			Headers: map[string]string{
@@ -124,16 +248,11 @@ func (c *rtspClient) run() {
 					"TEARDOWN",
 				}, ", "),
 			},
-			})
-			if err != nil {
-				c.log("ERR: %s", err)
-				return
-			}
+		}, nil
 
 	case "DESCRIBE":
 		if c.state != "STARTING" {
-				c.log("ERR: client is in state '%s'", c.state)
-				return
+			return nil, fmt.Errorf("client is in state '%s'", c.state)
 		}
 
 		sdp, err := func() ([]byte, error) {
@@ -147,11 +266,10 @@ func (c *rtspClient) run() {
 			return c.p.streamSdp, nil
 		}()
 		if err != nil {
-				c.log("ERR: %s", err)
-				return
+			return nil, err
 		}
 
-			err = rconn.WriteResponse(&rtsp.Response{
+		return &rtsp.Response{
 			StatusCode: 200,
 			Status:     "OK",
 			Headers: map[string]string{
@@ -160,27 +278,20 @@ func (c *rtspClient) run() {
 				"Content-Type": "application/sdp",
 			},
 			Content: sdp,
-			})
-			if err != nil {
-				c.log("ERR: %s", err)
-				return
-			}
+		}, nil
 
 	case "ANNOUNCE":
 		if c.state != "STARTING" {
-				c.log("ERR: client is in state '%s'", c.state)
-				return
+			return nil, fmt.Errorf("client is in state '%s'", c.state)
 		}
 
 		ct, ok := req.Headers["Content-Type"]
 		if !ok {
-				c.log("ERR: Content-Type header missing")
-				return
+			return nil, fmt.Errorf("Content-Type header missing")
 		}
 
 		if ct != "application/sdp" {
-				c.log("ERR: unsupported Content-Type '%s'", ct)
-				return
+			return nil, fmt.Errorf("unsupported Content-Type '%s'", ct)
 		}
 
 		err := func() error {
@@ -196,31 +307,25 @@ func (c *rtspClient) run() {
 			return nil
 		}()
 		if err != nil {
-				c.log("ERR: %s", err)
-				return
+			return nil, err
 		}
 
-			err = rconn.WriteResponse(&rtsp.Response{
+		c.p.mutex.Lock()
+		c.state = "ANNOUNCE"
+		c.p.mutex.Unlock()
+
+		return &rtsp.Response{
 			StatusCode: 200,
 			Status:     "OK",
 			Headers: map[string]string{
 				"CSeq": cseq,
 			},
-			})
-			if err != nil {
-				c.log("ERR: %s", err)
-				return
-			}
-
-			c.p.mutex.Lock()
-			c.state = "ANNOUNCE"
-			c.p.mutex.Unlock()
+		}, nil
 
 	case "SETUP":
 		transport, ok := req.Headers["Transport"]
 		if !ok {
-				c.log("ERR: transport header missing")
-				return
+			return nil, fmt.Errorf("transport header missing")
 		}
 
 		transports := make(map[string]struct{})
@@ -229,8 +334,7 @@ func (c *rtspClient) run() {
 		}
 
 		if _, ok := transports["unicast"]; !ok {
-				c.log("ERR: transport header does not contain unicast")
-				return
+			return nil, fmt.Errorf("transport header does not contain unicast")
 		}
 
 		getPorts := func() (int, int) {
@@ -267,11 +371,17 @@ func (c *rtspClient) run() {
 			if _, ok := transports["RTP/AVP"]; ok {
 				clientPort1, clientPort2 := getPorts()
 				if clientPort1 == 0 || clientPort2 == 0 {
-						c.log("ERR: transport header does not have valid client ports (%s)", transport)
-						return
+					return nil, fmt.Errorf("transport header does not have valid client ports (%s)", transport)
 				}
 
-					err = rconn.WriteResponse(&rtsp.Response{
+				c.p.mutex.Lock()
+				c.rtpProto = "udp"
+				c.rtpPort = clientPort1
+				c.rtcpPort = clientPort2
+				c.state = "PRE_PLAY"
+				c.p.mutex.Unlock()
+
+				return &rtsp.Response{
 					StatusCode: 200,
 					Status:     "OK",
 					Headers: map[string]string{
@@ -287,22 +397,16 @@ func (c *rtspClient) run() {
 						}, ";"),
 						"Session": "12345678",
 					},
-					})
-					if err != nil {
-						c.log("ERR: %s", err)
-						return
-					}
+				}, nil
 
+				// TCP
+			} else if _, ok := transports["RTP/AVP/TCP"]; ok {
 				c.p.mutex.Lock()
-					c.rtpProto = "udp"
-					c.rtpPort = clientPort1
-					c.rtcpPort = clientPort2
+				c.rtpProto = "tcp"
 				c.state = "PRE_PLAY"
 				c.p.mutex.Unlock()
 
-					// TCP
-				} else if _, ok := transports["RTP/AVP/TCP"]; ok {
-					err = rconn.WriteResponse(&rtsp.Response{
+				return &rtsp.Response{
 					StatusCode: 200,
 					Status:     "OK",
 					Headers: map[string]string{
@@ -316,37 +420,32 @@ func (c *rtspClient) run() {
 						}, ";"),
 						"Session": "12345678",
 					},
-					})
-					if err != nil {
-						c.log("ERR: %s", err)
-						return
-					}
-
-					c.p.mutex.Lock()
-					c.rtpProto = "tcp"
-					c.state = "PRE_PLAY"
-					c.p.mutex.Unlock()
+				}, nil
 
 			} else {
-					c.log("ERR: transport header does not contain a valid protocol (RTP/AVP or RTP/AVP/TCP) (%s)", transport)
-					return
+				return nil, fmt.Errorf("transport header does not contain a valid protocol (RTP/AVP or RTP/AVP/TCP) (%s)", transport)
 			}
 
 		// record
 		case "ANNOUNCE":
 			if _, ok := transports["mode=record"]; !ok {
-					c.log("ERR: transport header does not contain mode=record")
-					return
+				return nil, fmt.Errorf("transport header does not contain mode=record")
 			}
 
 			if _, ok := transports["RTP/AVP/UDP"]; ok {
 				clientPort1, clientPort2 := getPorts()
 				if clientPort1 == 0 || clientPort2 == 0 {
-						c.log("ERR: transport header does not have valid client ports (%s)", transport)
-						return
+					return nil, fmt.Errorf("transport header does not have valid client ports (%s)", transport)
 				}
 
-					err = rconn.WriteResponse(&rtsp.Response{
+				c.p.mutex.Lock()
+				c.rtpProto = "udp"
+				c.rtpPort = clientPort1
+				c.rtcpPort = clientPort2
+				c.state = "PRE_RECORD"
+				c.p.mutex.Unlock()
+
+				return &rtsp.Response{
 					StatusCode: 200,
 					Status:     "OK",
 					Headers: map[string]string{
@@ -360,21 +459,15 @@ func (c *rtspClient) run() {
 						}, ";"),
 						"Session": "12345678",
 					},
-					})
-					if err != nil {
-						c.log("ERR: %s", err)
-						return
-					}
+				}, nil
 
+			} else if _, ok := transports["RTP/AVP/TCP"]; ok {
 				c.p.mutex.Lock()
-					c.rtpProto = "udp"
-					c.rtpPort = clientPort1
-					c.rtcpPort = clientPort2
+				c.rtpProto = "tcp"
 				c.state = "PRE_RECORD"
 				c.p.mutex.Unlock()
 
-				} else if _, ok := transports["RTP/AVP/TCP"]; ok {
-					err = rconn.WriteResponse(&rtsp.Response{
+				return &rtsp.Response{
 					StatusCode: 200,
 					Status:     "OK",
 					Headers: map[string]string{
@@ -387,68 +480,33 @@ func (c *rtspClient) run() {
 						}, ";"),
 						"Session": "12345678",
 					},
-					})
-					if err != nil {
-						c.log("ERR: %s", err)
-						return
-					}
-
-					c.p.mutex.Lock()
-					c.rtpProto = "tcp"
-					c.state = "PRE_RECORD"
-					c.p.mutex.Unlock()
+				}, nil
 
 			} else {
-					c.log("ERR: transport header does not contain a valid protocol (RTP/AVP or RTP/AVP/TCP) (%s)", transport)
-					return
+				return nil, fmt.Errorf("transport header does not contain a valid protocol (RTP/AVP or RTP/AVP/TCP) (%s)", transport)
 			}
 
 		default:
-				c.log("ERR: client is in state '%s'", c.state)
-				return
+			return nil, fmt.Errorf("client is in state '%s'", c.state)
 		}
 
 	case "PLAY":
 		if c.state != "PRE_PLAY" {
-				c.log("ERR: client is in state '%s'", c.state)
-				return
+			return nil, fmt.Errorf("client is in state '%s'", c.state)
 		}
 
-			err = rconn.WriteResponse(&rtsp.Response{
+		return &rtsp.Response{
 			StatusCode: 200,
 			Status:     "OK",
 			Headers: map[string]string{
 				"CSeq":    cseq,
 				"Session": "12345678",
 			},
-			})
-			if err != nil {
-				c.log("ERR: %s", err)
-				return
-			}
-
-			c.log("is receiving (via %s)", c.rtpProto)
-
-			c.p.mutex.Lock()
-			c.state = "PLAY"
-			c.p.mutex.Unlock()
-
-			// when rtp protocol is TCP, the RTSP connection becomes a RTP connection.
-			// receive RTP feedback, do not parse it, wait until connection closes.
-			if c.rtpProto == "tcp" {
-				buf := make([]byte, 1024)
-				for {
-					_, err := c.nconn.Read(buf)
-					if err != nil {
-						return
-					}
-				}
-			}
+		}, errPlay
 
 	case "PAUSE":
 		if c.state != "PLAY" {
-				c.log("ERR: client is in state '%s'", c.state)
-				return
+			return nil, fmt.Errorf("client is in state '%s'", c.state)
 		}
 
 		c.log("paused receiving")
@@ -457,86 +515,33 @@ func (c *rtspClient) run() {
 		c.state = "PRE_PLAY"
 		c.p.mutex.Unlock()
 
-			err = rconn.WriteResponse(&rtsp.Response{
+		return &rtsp.Response{
 			StatusCode: 200,
 			Status:     "OK",
 			Headers: map[string]string{
 				"CSeq":    cseq,
 				"Session": "12345678",
 			},
-			})
-			if err != nil {
-				c.log("ERR: %s", err)
-				return
-			}
+		}, nil
 
 	case "RECORD":
 		if c.state != "PRE_RECORD" {
-				c.log("ERR: client is in state '%s'", c.state)
-				return
+			return nil, fmt.Errorf("client is in state '%s'", c.state)
 		}
 
-			err = rconn.WriteResponse(&rtsp.Response{
+		return &rtsp.Response{
 			StatusCode: 200,
 			Status:     "OK",
 			Headers: map[string]string{
 				"CSeq":    cseq,
 				"Session": "12345678",
 			},
-			})
-			if err != nil {
-				c.log("ERR: %s", err)
-				return
-			}
-
-			c.log("is publishing (via %s)", c.rtpProto)
-
-			c.p.mutex.Lock()
-			c.state = "RECORD"
-			c.p.mutex.Unlock()
-
-			// when rtp protocol is TCP, the RTSP connection becomes a RTP connection.
-			// receive RTP feedback, do not parse it, wait until connection closes.
-			if c.rtpProto == "tcp" {
-				packet := make([]byte, 2048)
-				bconn := bufio.NewReader(c.nconn)
-				for {
-					byts, err := bconn.Peek(4)
-					if err != nil {
-						return
-					}
-					bconn.Discard(4)
-
-					if byts[0] != 0x24 {
-						c.log("ERR: wrong magic byte")
-						return
-					}
-
-					if byts[1] != 0x00 {
-						c.log("ERR: wrong channel")
-						return
-					}
-
-					plen := binary.BigEndian.Uint16(byts[2:])
-					if plen > 2048 {
-						c.log("ERR: packet len > 2048")
-						return
-					}
-
-					_, err = io.ReadFull(bconn, packet[:plen])
-					if err != nil {
-						return
-					}
-
-					c.p.handleRtp(packet[:plen])
-				}
-			}
+		}, errRecord
 
 	case "TEARDOWN":
-			return
+		return nil, errTeardown
 
 	default:
-			c.log("ERR: method %s unhandled", req.Method)
-		}
+		return nil, fmt.Errorf("unhandled method '%s'", req.Method)
 	}
 }