client: support writing to ONVIF back channels (#101) (#462)

client.go

@@ -245,6 +245,8 @@ type Client struct {
 	UserAgent string
 	// disable automatic RTCP sender reports.
 	DisableRTCPSenderReports bool
+	// explicitly request back channels to the server.
+	RequestBackChannels bool
 	// pointer to a variable that stores received bytes.
 	BytesReceived *uint64
 	// pointer to a variable that stores sent bytes.
@@ -301,6 +303,8 @@ type Client struct {
 	lastDescribeURL      *base.URL
 	baseURL              *base.URL
 	effectiveTransport   *Transport
+	backChannelSetupped  bool
+	stdChannelSetupped   bool
 	medias               map[*description.Media]*clientMedia
 	tcpCallbackByChannel map[int]readFunc
 	lastRange            *headers.Range
@@ -662,9 +666,16 @@ func (c *Client) doClose() {
 	}
 
 	if c.nconn != nil && c.baseURL != nil {
+		header := base.Header{}
+
+		if c.backChannelSetupped {
+			header["Require"] = base.HeaderValue{"www.onvif.org/ver20/backchannel"}
+		}
+
 		c.do(&base.Request{ //nolint:errcheck
 			Method: base.Teardown,
 			URL:    c.baseURL,
+			Header: header,
 		}, true)
 	}
 
@@ -696,6 +707,8 @@ func (c *Client) reset() {
 	c.useGetParameter = false
 	c.baseURL = nil
 	c.effectiveTransport = nil
+	c.backChannelSetupped = false
+	c.stdChannelSetupped = false
 	c.medias = nil
 	c.tcpCallbackByChannel = nil
 }
@@ -776,13 +789,13 @@ func (c *Client) trySwitchingProtocol2(medi *description.Media, baseURL *base.UR
 
 func (c *Client) startReadRoutines() {
 	// allocate writer here because it's needed by RTCP receiver / sender
-	if c.state == clientStatePlay {
+	if c.state == clientStateRecord || c.backChannelSetupped {
+		c.writer.allocateBuffer(c.WriteQueueSize)
+	} else {
 		// when reading, buffer is only used to send RTCP receiver reports,
 		// that are much smaller than RTP packets and are sent at a fixed interval.
 		// decrease RAM consumption by allocating less buffers.
 		c.writer.allocateBuffer(8)
-	} else {
-		c.writer.allocateBuffer(c.WriteQueueSize)
 	}
 
 	c.timeDecoder = rtptime.NewGlobalDecoder()
@@ -791,7 +804,7 @@ func (c *Client) startReadRoutines() {
 		cm.start()
 	}
 
-	if c.state == clientStatePlay {
+	if c.state == clientStatePlay && c.stdChannelSetupped {
 		c.keepaliveTimer = time.NewTimer(c.keepalivePeriod)
 
 		switch *c.effectiveTransport {
@@ -991,7 +1004,7 @@ func (c *Client) isInTCPTimeout() bool {
 func (c *Client) doCheckTimeout() error {
 	if *c.effectiveTransport == TransportUDP ||
 		*c.effectiveTransport == TransportUDPMulticast {
-		if c.checkTimeoutInitial {
+		if c.checkTimeoutInitial && !c.backChannelSetupped {
 			c.checkTimeoutInitial = false
 
 			if c.atLeastOneUDPPacketHasBeenReceived() {
@@ -1092,12 +1105,18 @@ func (c *Client) doDescribe(u *base.URL) (*description.Session, *base.Response,
 		return nil, nil, err
 	}
 
+	header := base.Header{
+		"Accept": base.HeaderValue{"application/sdp"},
+	}
+
+	if c.RequestBackChannels {
+		header["Require"] = base.HeaderValue{"www.onvif.org/ver20/backchannel"}
+	}
+
 	res, err := c.do(&base.Request{
 		Method: base.Describe,
 		URL:    u,
-		Header: base.Header{
-			"Accept": base.HeaderValue{"application/sdp"},
-		},
+		Header: header,
 	}, false)
 	if err != nil {
 		return nil, nil, err
@@ -1334,12 +1353,18 @@ func (c *Client) doSetup(
 		return nil, err
 	}
 
+	header := base.Header{
+		"Transport": th.Marshal(),
+	}
+
+	if medi.IsBackChannel {
+		header["Require"] = base.HeaderValue{"www.onvif.org/ver20/backchannel"}
+	}
+
 	res, err := c.do(&base.Request{
 		Method: base.Setup,
 		URL:    mediaURL,
-		Header: base.Header{
-			"Transport": th.Marshal(),
-		},
+		Header: header,
 	}, false)
 	if err != nil {
 		cm.close()
@@ -1509,6 +1534,12 @@ func (c *Client) doSetup(
 	c.baseURL = baseURL
 	c.effectiveTransport = &desiredTransport
 
+	if medi.IsBackChannel {
+		c.backChannelSetupped = true
+	} else {
+		c.stdChannelSetupped = true
+	}
+
 	if c.state == clientStateInitial {
 		c.state = clientStatePrePlay
 	}
@@ -1590,12 +1621,18 @@ func (c *Client) doPlay(ra *headers.Range) (*base.Response, error) {
 		}
 	}
 
+	header := base.Header{
+		"Range": ra.Marshal(),
+	}
+
+	if c.backChannelSetupped {
+		header["Require"] = base.HeaderValue{"www.onvif.org/ver20/backchannel"}
+	}
+
 	res, err := c.do(&base.Request{
 		Method: base.Play,
 		URL:    c.baseURL,
-		Header: base.Header{
-			"Range": ra.Marshal(),
-		},
+		Header: header,
 	}, false)
 	if err != nil {
 		c.stopReadRoutines()