protocol/rtsp: more commenting and started writing client_test.go to check the behaviour of the rtcp client

protocol/rtcp/client.go

@@ -59,14 +59,14 @@ func NewClient(clientAddress, serverAddress, name string, sendInterval time.Dura
 }
 
 // Start starts the listen and send routines. This will start the process of
-// receiving and parsing SenderReports, and the process of sending receiver
+// receiving and parsing sender reports, and the process of sending receiver
 // reports to the server.
 func (c *client) Start() {
 	go c.listen()
 	go c.send()
 }
 
-// Listen reads from the UDP connection and parses SenderReports.
+// listen reads from the UDP connection and parses SenderReports.
 func (c *client) listen() {
 	conn, err := net.ListenUDP("udp", c.cAddr)
 	if err != nil {
@@ -79,7 +79,7 @@ func (c *client) listen() {
 	}
 }
 
-// send write sender reports to the server.
+// send writes receiver reports to the server.
 func (c *client) send() {
 	conn, err := net.DialUDP("udp", c.cAddr, c.sAddr)
 	if err != nil {
@@ -154,12 +154,15 @@ func (c *client) parse(buf []byte) {
 	c.setSenderTs(msw, lsw)
 }
 
+// UpdateSequence will allow updating of the highest sequence number received
+// through an rtp stream.
 func (c *client) UpdateSequence(s uint32) {
 	c.mu.Lock()
 	c.sequence = s
 	c.mu.Unlock()
 }
 
+// highestSequence will return the highest sequence number received through rtp.
 func (c *client) highestSequence() uint32 {
 	var s uint32
 	c.mu.Lock()
@@ -168,10 +171,13 @@ func (c *client) highestSequence() uint32 {
 	return s
 }
 
+// jitter returns the interarrival jitter as described by RTCP specifications:
+// https://tools.ietf.org/html/rfc3550
 func (c *client) jitter() uint32 {
 	return 0
 }
 
+// setSenderTs allows us to safely set the current sender report timestamp.
 func (c *client) setSenderTs(msw, lsw uint32) {
 	c.mu.Lock()
 	binary.BigEndian.PutUint32(c.senderTs[:], msw)
@@ -179,6 +185,7 @@ func (c *client) setSenderTs(msw, lsw uint32) {
 	c.mu.Unlock()
 }
 
+// lastSenderTs returns the timestamp of the most recent sender report.
 func (c *client) lastSenderTs() uint32 {
 	var ts uint32
 	c.mu.Lock()
@@ -187,6 +194,8 @@ func (c *client) lastSenderTs() uint32 {
 	return ts
 }
 
+// delay returns the duration between the receive time of the last sender report
+// and now. This is called when forming a receiver report.
 func (c *client) delay() uint32 {
 	var receiveTime time.Time
 	c.mu.Lock()
@@ -196,6 +205,7 @@ func (c *client) delay() uint32 {
 	return uint32(now.Sub(receiveTime).Seconds() / delayUnit)
 }
 
+// received is called when a sender report is received to mark the receive time.
 func (c *client) received() {
 	c.mu.Lock()
 	c.receiveTime = time.Now()

protocol/rtcp/client_test.go

@@ -0,0 +1,30 @@
+package rtcp
+
+import (
+	"net"
+	"testing"
+)
+
+func TestReceiveAndSend(t *testing.T) {
+	quit := make(chan struct{})
+	go testServer(quit)
+}
+
+func testServer(quit chan struct{}, t *testing.T) {
+	const testServerAddr = "localhost:8000"
+	sAddr, err := net.ResolveUDPAddr("udp", testServerAddr)
+	if err != nil {
+		t.Fatalf("could not resolve test server address, failed with error: %v", err)
+	}
+
+	conn, err := net.DialUDP("udp", nil, sAddr)
+	if err != nil {
+		t.Fatalf("could not dial, failed with error: %v", err)
+	}
+
+	select {
+	case <-quit:
+		return
+	default:
+	}
+}

protocol/rtcp/parse.go

@@ -7,14 +7,12 @@ import (
 
 // Timestamp gets the timestamp from a receiver report and returns as the most
 // significant word, and the least significant word. If the given bytes do not
-// represent a valid receiver report, and error is returned.
+// represent a valid receiver report, an error is returned.
 func Timestamp(buf []byte) (msw, lsw uint32, err error) {
-	// First check version of rtcp
 	if (buf[0] & 0xc0 >> 6) != 2 {
 		return 0, 0, errors.New("incompatible RTCP version")
 	}
 
-	// Check type of packet
 	if buf[1] != typeSenderReport {
 		return 0, 0, errors.New("rtcp packet is not of sender report type")
 	}

protocol/rtcp/rtcp.go

@@ -16,18 +16,20 @@ const (
 	typeCName = 1
 )
 
+// MISC.
 const (
 	reportBlockSize = 6
 )
 
+// ReceiverReport describes an RTCP receiver report packet.
 type ReceiverReport struct {
-	Header
-
-	SenderSSRC uint32
-	Blocks     []ReportBlock
-	Extensions [][4]byte
+	Header                   // Standard RTCP packet header.
+	SenderSSRC uint32        // SSRC of the sender of this report.
+	Blocks     []ReportBlock // Report blocks.
+	Extensions [][4]byte     // Contains any extensions to the packet.
 }
 
+// Bytes returns a []byte of the ReceiverReport r.
 func (r *ReceiverReport) Bytes() []byte {
 	l := 8 + 4*reportBlockSize*len(r.Blocks) + 4*len(r.Extensions)
 	buf := make([]byte, l)
@@ -61,6 +63,7 @@ func (r *ReceiverReport) Bytes() []byte {
 	return buf
 }
 
+// ReportBlock describes an RTCP report block used in Sender/Receiver Reports.
 type ReportBlock struct {
 	SSRC            uint32 // Source identifier.
 	FractionLost    uint8  // Fraction of packets lost.
@@ -71,12 +74,13 @@ type ReportBlock struct {
 	DLSR            uint32 // Delay since last sender report.
 }
 
+// SourceDescription describes a source description RTCP packet.
 type SourceDescription struct {
-	Header
-
-	Chunks []Chunk
+	Header         // Standard RTCP packet header.
+	Chunks []Chunk // Chunks to describe items of each SSRC.
 }
 
+// Bytes returns an []byte of the SourceDescription d.
 func (d *SourceDescription) Bytes() []byte {
 	bodyLen := d.bodyLen()
 	rem := bodyLen % 4
@@ -102,6 +106,7 @@ func (d *SourceDescription) Bytes() []byte {
 	return buf
 }
 
+// bodyLen calculates the body length of a source description packet in bytes.
 func (d *SourceDescription) bodyLen() int {
 	l := 0
 	for _, c := range d.Chunks {
@@ -110,6 +115,7 @@ func (d *SourceDescription) bodyLen() int {
 	return l
 }
 
+// Header describes a standard RTCP packet header.
 type Header struct {
 	Version     uint8 // RTCP version.
 	Padding     bool  // Padding indicator.
@@ -117,16 +123,19 @@ type Header struct {
 	Type        uint8 // Type of RTCP packet.
 }
 
+// SDESItem describes a source description item.
 type SDESItem struct {
-	Type uint8
-	Text []byte
+	Type uint8  // Type of item.
+	Text []byte // Item text.
 }
 
+// Chunk describes a source description chunk for a given SSRC.
 type Chunk struct {
-	SSRC  uint32
-	Items []SDESItem
+	SSRC  uint32     // SSRC of the source being described by the below items.
+	Items []SDESItem // Items describing the source.
 }
 
+// len returns the len of a chunk in bytes.
 func (c *Chunk) len() int {
 	tot := 4
 	for _, i := range c.Items {
@@ -135,6 +144,8 @@ func (c *Chunk) len() int {
 	return tot
 }
 
+// writeHeader writes the standard RTCP header given a buffer to write to and l
+// the RTCP body length that needs to be encoded into the header.
 func (h Header) writeHeader(buf []byte, l int) {
 	buf[0] = h.Version<<6 | asByte(h.Padding)<<5 | 0x1f&h.ReportCount
 	buf[1] = h.Type

protocol/rtcp/rtcp_test.go

@@ -6,6 +6,8 @@ import (
 	"testing"
 )
 
+// TestReceiverReportBytes checks that we can correctly obtain a []byte of an
+// RTCP receiver report from the struct representation.
 func TestReceiverReportBytes(t *testing.T) {
 	expect := []byte{
 		0x81, 0xc9, 0x00, 0x07,
@@ -48,6 +50,8 @@ func TestReceiverReportBytes(t *testing.T) {
 	}
 }
 
+// TestSourceDescriptionBytes checks that we can correctly obtain a []byte of an
+// RTCP source description from the struct representation.
 func TestSourceDescriptionBytes(t *testing.T) {
 	expect := []byte{
 		0x81, 0xca, 0x00, 0x04,