protocol/rtcp: wrote Bytes for for SourceDescription type

protocol/rtcp/rtcp.go

@@ -10,24 +10,6 @@ const (
 	reportBlockSize = 6
 )
 
-type Header struct {
-	Version     uint8  // RTCP version.
-	Padding     bool   // Padding indicator.
-	ReportCount uint8  // Number of reports contained.
-	Type        uint8  // Type of RTCP packet.
-	SSRC        uint32 // Source identifier.
-}
-
-type ReportBlock struct {
-	SSRC            uint32 // Source identifier.
-	FractionLost    uint8  // Fraction of packets lost.
-	PacketsLost     uint32 // Cumulative number of packets lost.
-	HighestSequence uint32 // Extended highest sequence number received.
-	Jitter          uint32 // Interarrival jitter.
-	LSR             uint32 // Last sender report timestamp.
-	DLSR            uint32 // Delay since last sender report.
-}
-
 type ReceiverReport struct {
 	Header
 
@@ -39,13 +21,8 @@ func (r *ReceiverReport) Bytes() []byte {
 	l := 8 + 4*reportBlockSize*len(r.Blocks) + 4*len(r.Extensions)
 	buf := make([]byte, l)
 
-	buf[0] = r.Version<<6 | asByte(r.Padding)<<5 | 0x1f&r.ReportCount
-	buf[1] = r.Type
-
 	l = 1 + reportBlockSize*len(r.Blocks) + len(r.Extensions)
-	binary.BigEndian.PutUint16(buf[2:], uint16(l))
-
-	buf[4] = byte(r.SSRC)
+	r.writeHeader(buf, l)
 
 	idx := 8
 	for _, b := range r.Blocks {
@@ -65,18 +42,13 @@ func (r *ReceiverReport) Bytes() []byte {
 	}
 
 	for _, e := range r.Extensions {
-		binary.BigEndian.PutUint32(buf[idx:], binary.BigEndian.Uint32(e[:]))
+		copy(buf[idx:], e[:])
 		idx += 4
 	}
 
 	return buf
 }
 
-type Chunk struct {
-	Type uint8
-	Test []byte
-}
-
 type SourceDescription struct {
 	Header
 
@@ -84,7 +56,75 @@ type SourceDescription struct {
 }
 
 func (d *SourceDescription) Bytes() []byte {
+	bodyLen := d.bodyLen()
+	l := 8 + bodyLen
+	buf := make([]byte, l)
+	d.writeHeader(buf, bodyLen/4)
+	idx := 8
+	for _, c := range d.Chunks {
+		binary.BigEndian.PutUint32(buf[idx:], c.SSRC)
+		idx += 4
+		for _, i := range c.Items {
+			buf[idx] = i.Type
+			idx++
+			buf[idx] = byte(len(i.Text))
+			idx++
+			copy(buf[idx:], i.Text)
+			idx += len(i.Text)
+		}
+	}
+	return buf
+}
 
+func (d *SourceDescription) bodyLen() int {
+	l := 0
+	for _, c := range d.Chunks {
+		l += c.len()
+	}
+	return l
+}
+
+type Header struct {
+	Version     uint8  // RTCP version.
+	Padding     bool   // Padding indicator.
+	ReportCount uint8  // Number of reports contained.
+	Type        uint8  // Type of RTCP packet.
+	SSRC        uint32 // Source identifier.
+}
+
+type ReportBlock struct {
+	SSRC            uint32 // Source identifier.
+	FractionLost    uint8  // Fraction of packets lost.
+	PacketsLost     uint32 // Cumulative number of packets lost.
+	HighestSequence uint32 // Extended highest sequence number received.
+	Jitter          uint32 // Interarrival jitter.
+	LSR             uint32 // Last sender report timestamp.
+	DLSR            uint32 // Delay since last sender report.
+}
+
+type SDESItem struct {
+	Type uint8
+	Text []byte
+}
+
+type Chunk struct {
+	SSRC  uint32
+	Items []SDESItem
+}
+
+func (c *Chunk) len() int {
+	tot := 4
+	for _, i := range c.Items {
+		tot += 2 + len(i.Text)
+	}
+	return tot
+}
+
+func (h Header) writeHeader(buf []byte, l int) {
+	buf[0] = h.Version<<6 | asByte(h.Padding)<<5 | 0x1f&h.ReportCount
+	buf[1] = h.Type
+	binary.BigEndian.PutUint16(buf[2:], uint16(l))
+	buf[4] = byte(h.SSRC)
 }
 
 func asByte(b bool) byte {