rtpreorderer: return all buffered packets when the buffer is full

(https://github.com/aler9/rtsp-simple-server/issues/1049)

pkg/rtpreorderer/reorderer.go

@@ -42,51 +42,77 @@ func (r *Reorderer) Process(pkt *rtp.Packet) []*rtp.Packet {
 		return nil
 	}
 
-	// buffer is full. clear buffer and return current packet.
+	// there's a missing packet and buffer is full.
+	// return entire buffer and clear it.
 	if relPos >= bufferSize {
+		n := 1
+		for i := uint16(0); i < bufferSize; i++ {
+			p := (r.absPos + i) & (bufferSize - 1)
+			if r.buffer[p] != nil {
+				n++
+			}
+		}
+
+		ret := make([]*rtp.Packet, n)
+		pos := 0
+
+		for i := uint16(0); i < bufferSize; i++ {
+			p := (r.absPos + i) & (bufferSize - 1)
+			if r.buffer[p] != nil {
+				ret[pos] = r.buffer[p]
+				pos++
+			}
+		}
+
+		ret[pos] = pkt
+
 		for i := 0; i < bufferSize; i++ {
 			r.buffer[i] = nil
 		}
+
 		r.expectedSeqNum = pkt.SequenceNumber + 1
-		return []*rtp.Packet{pkt}
+		return ret
 	}
 
 	// there's a missing packet
 	if relPos != 0 {
 		p := (r.absPos + relPos) & (bufferSize - 1)
 
-		// current packet is a duplicate. discard.
+		// current packet is a duplicate. discard
 		if r.buffer[p] != nil {
 			return nil
 		}
 
-		// put current packet in buffer.
+		// put current packet in buffer
 		r.buffer[p] = pkt
 		return nil
 	}
 
-	count := uint16(1)
+	// all packets have been received correctly.
+	// return them
+
+	n := uint16(1)
 	for {
-		p := (r.absPos + count) & (bufferSize - 1)
+		p := (r.absPos + n) & (bufferSize - 1)
 		if r.buffer[p] == nil {
 			break
 		}
-		count++
+		n++
 	}
 
-	ret := make([]*rtp.Packet, count)
+	ret := make([]*rtp.Packet, n)
 	ret[0] = pkt
 
 	r.absPos++
 	r.absPos &= (bufferSize - 1)
 
-	for i := uint16(1); i < count; i++ {
+	for i := uint16(1); i < n; i++ {
 		ret[i], r.buffer[r.absPos] = r.buffer[r.absPos], nil
 		r.absPos++
 		r.absPos &= (bufferSize - 1)
 	}
 
-	r.expectedSeqNum = pkt.SequenceNumber + count
+	r.expectedSeqNum = pkt.SequenceNumber + n
 
 	return ret
 }

pkg/rtpreorderer/reorderer_test.go

@@ -155,21 +155,6 @@ func TestReorder(t *testing.T) {
 				},
 			},
 		},
-		{
-			// buffer is full
-			&rtp.Packet{
-				Header: rtp.Header{
-					SequenceNumber: 67,
-				},
-			},
-			[]*rtp.Packet{
-				{
-					Header: rtp.Header{
-						SequenceNumber: 67,
-					},
-				},
-			},
-		},
 	}
 
 	r := New()
@@ -180,3 +165,50 @@ func TestReorder(t *testing.T) {
 		require.Equal(t, entry.out, out)
 	}
 }
+
+func TestBufferIsFull(t *testing.T) {
+	r := New()
+	r.absPos = 25
+
+	out := r.Process(&rtp.Packet{
+		Header: rtp.Header{
+			SequenceNumber: 1,
+		},
+	})
+	require.Equal(t, []*rtp.Packet{{
+		Header: rtp.Header{
+			SequenceNumber: 1,
+		},
+	}}, out)
+
+	var expected []*rtp.Packet
+
+	for i := uint16(0); i < 63; i++ {
+		out := r.Process(&rtp.Packet{
+			Header: rtp.Header{
+				SequenceNumber: 3 + i,
+			},
+		})
+		require.Equal(t, []*rtp.Packet(nil), out)
+
+		expected = append(expected, &rtp.Packet{
+			Header: rtp.Header{
+				SequenceNumber: 3 + i,
+			},
+		})
+	}
+
+	out = r.Process(&rtp.Packet{
+		Header: rtp.Header{
+			SequenceNumber: 3 + 64,
+		},
+	})
+
+	expected = append(expected, &rtp.Packet{
+		Header: rtp.Header{
+			SequenceNumber: 3 + 64,
+		},
+	})
+
+	require.Equal(t, expected, out)
+}