protocol/rtcp: using defer where I can

protocol/rtcp/client.go

@@ -243,11 +243,9 @@ func (c *client) UpdateSequence(s uint32) {
 
 // highestSequence will return the highest sequence number received through RTP.
 func (c *client) highestSequence() uint32 {
-	var s uint32
 	c.mu.Lock()
-	s = c.sequence
-	c.mu.Unlock()
-	return s
+	defer c.mu.Unlock()
+	return c.sequence
 }
 
 // jitter returns the interarrival jitter as described by RTCP specifications:
@@ -259,34 +257,30 @@ func (c *client) jitter() uint32 {
 // setSenderTs allows us to safely set the current sender report timestamp.
 func (c *client) setSenderTs(msw, lsw uint32) {
 	c.mu.Lock()
+	defer c.mu.Unlock()
 	binary.BigEndian.PutUint32(c.senderTs[:], msw)
 	binary.BigEndian.PutUint32(c.senderTs[4:], lsw)
-	c.mu.Unlock()
 }
 
 // lastSenderTs returns the timestamp of the most recent sender report.
 func (c *client) lastSenderTs() uint32 {
-	var ts uint32
 	c.mu.Lock()
-	ts = binary.BigEndian.Uint32(c.senderTs[2:])
-	c.mu.Unlock()
-	return ts
+	defer c.mu.Unlock()
+	return binary.BigEndian.Uint32(c.senderTs[2:])
 }
 
 // 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()
-	receiveTime = c.receiveTime
-	c.mu.Unlock()
+	defer c.mu.Unlock()
 	now := time.Now()
-	return uint32(now.Sub(receiveTime).Seconds() / delayUnit)
+	return uint32(now.Sub(c.receiveTime).Seconds() / delayUnit)
 }
 
 // received is called when a sender report is received to mark the receive time.
 func (c *client) received() {
 	c.mu.Lock()
+	defer c.mu.Unlock()
 	c.receiveTime = time.Now()
-	c.mu.Unlock()
 }

protocol/rtcp/parse.go

@@ -39,7 +39,7 @@ func Timestamp(buf []byte) (msw, lsw uint32, err error) {
 	if len(buf) < 4 {
 		return 0, 0, errors.New("bad RTCP packet, not of sufficient length")
 	}
-	if (buf[0]&0xc0)>>6 != rtpVer {
+	if (buf[0]&0xc0)>>6 != rtcpVer {
 		return 0, 0, errors.New("incompatible RTCP version")
 	}