rtmp: implement acknowledge mechanism

internal/rtmp/bytecounter/reader.go

@@ -0,0 +1,37 @@
+package bytecounter
+
+import (
+	"bufio"
+	"io"
+)
+
+type readerInner struct {
+	r     io.Reader
+	count uint32
+}
+
+func (r *readerInner) Read(p []byte) (int, error) {
+	n, err := r.r.Read(p)
+	r.count += uint32(n)
+	return n, err
+}
+
+// Reader allows to count read bytes.
+type Reader struct {
+	ri *readerInner
+	*bufio.Reader
+}
+
+// NewReader allocates a Reader.
+func NewReader(r io.Reader) *Reader {
+	ri := &readerInner{r: r}
+	return &Reader{
+		ri:     ri,
+		Reader: bufio.NewReader(ri),
+	}
+}
+
+// Count returns read bytes.
+func (r Reader) Count() uint32 {
+	return r.ri.count
+}

internal/rtmp/bytecounter/readwriter.go

@@ -0,0 +1,19 @@
+package bytecounter
+
+import (
+	"io"
+)
+
+// ReadWriter allows to count read and written bytes.
+type ReadWriter struct {
+	*Reader
+	*Writer
+}
+
+// NewReadWriter allocates a ReadWriter.
+func NewReadWriter(rw io.ReadWriter) *ReadWriter {
+	return &ReadWriter{
+		Reader: NewReader(rw),
+		Writer: NewWriter(rw),
+	}
+}

internal/rtmp/bytecounter/writer.go

@@ -0,0 +1,30 @@
+package bytecounter
+
+import (
+	"io"
+)
+
+// Writer allows to count written bytes.
+type Writer struct {
+	w     io.Writer
+	count uint32
+}
+
+// NewWriter allocates a Writer.
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{
+		w: w,
+	}
+}
+
+// Write implements io.Writer.
+func (w *Writer) Write(p []byte) (int, error) {
+	n, err := w.w.Write(p)
+	w.count += uint32(n)
+	return n, err
+}
+
+// Count returns written bytes.
+func (w Writer) Count() uint32 {
+	return w.count
+}

internal/rtmp/chunk/chunk.go

@@ -0,0 +1,11 @@
+package chunk
+
+import (
+	"io"
+)
+
+// Chunk is a chunk.
+type Chunk interface {
+	Read(io.Reader, uint32) error
+	Write() ([]byte, error)
+}

internal/rtmp/chunk/chunk0.go

@@ -18,7 +18,7 @@ type Chunk0 struct {
 }
 
 // Read reads the chunk.
-func (c *Chunk0) Read(r io.Reader, chunkMaxBodyLen int) error {
+func (c *Chunk0) Read(r io.Reader, chunkMaxBodyLen uint32) error {
 	header := make([]byte, 12)
 	_, err := r.Read(header)
 	if err != nil {
@@ -31,7 +31,7 @@ func (c *Chunk0) Read(r io.Reader, chunkMaxBodyLen int) error {
 	c.Type = MessageType(header[7])
 	c.MessageStreamID = uint32(header[8])<<24 | uint32(header[9])<<16 | uint32(header[10])<<8 | uint32(header[11])
 
-	chunkBodyLen := int(c.BodyLen)
+	chunkBodyLen := c.BodyLen
 	if chunkBodyLen > chunkMaxBodyLen {
 		chunkBodyLen = chunkMaxBodyLen
 	}

internal/rtmp/chunk/chunk1.go

@@ -19,7 +19,7 @@ type Chunk1 struct {
 }
 
 // Read reads the chunk.
-func (c *Chunk1) Read(r io.Reader, chunkMaxBodyLen int) error {
+func (c *Chunk1) Read(r io.Reader, chunkMaxBodyLen uint32) error {
 	header := make([]byte, 8)
 	_, err := r.Read(header)
 	if err != nil {
@@ -31,7 +31,7 @@ func (c *Chunk1) Read(r io.Reader, chunkMaxBodyLen int) error {
 	c.BodyLen = uint32(header[4])<<16 | uint32(header[5])<<8 | uint32(header[6])
 	c.Type = MessageType(header[7])
 
-	chunkBodyLen := int(c.BodyLen)
+	chunkBodyLen := (c.BodyLen)
 	if chunkBodyLen > chunkMaxBodyLen {
 		chunkBodyLen = chunkMaxBodyLen
 	}

internal/rtmp/chunk/chunk2.go

@@ -15,7 +15,7 @@ type Chunk2 struct {
 }
 
 // Read reads the chunk.
-func (c *Chunk2) Read(r io.Reader, chunkBodyLen int) error {
+func (c *Chunk2) Read(r io.Reader, chunkBodyLen uint32) error {
 	header := make([]byte, 4)
 	_, err := r.Read(header)
 	if err != nil {

internal/rtmp/chunk/chunk3.go

@@ -16,7 +16,7 @@ type Chunk3 struct {
 }
 
 // Read reads the chunk.
-func (c *Chunk3) Read(r io.Reader, chunkBodyLen int) error {
+func (c *Chunk3) Read(r io.Reader, chunkBodyLen uint32) error {
 	header := make([]byte, 1)
 	_, err := r.Read(header)
 	if err != nil {

internal/rtmp/conn_test.go

@@ -1,7 +1,6 @@
 package rtmp
 
 import (
-	"bufio"
 	"net"
 	"net/url"
 	"strings"
@@ -13,6 +12,7 @@ import (
 	"github.com/notedit/rtmp/format/flv/flvio"
 	"github.com/stretchr/testify/require"
 
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/handshake"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/message"
 )
@@ -114,7 +114,7 @@ func TestReadTracks(t *testing.T) {
 			conn, err := net.Dial("tcp", "127.0.0.1:9121")
 			require.NoError(t, err)
 			defer conn.Close()
-			br := bufio.NewReader(conn)
+			bc := bytecounter.NewReadWriter(conn)
 
 			// C->S handshake C0
 			err = handshake.C0S0{}.Write(conn)
@@ -126,27 +126,26 @@ func TestReadTracks(t *testing.T) {
 			require.NoError(t, err)
 
 			// S->C handshake S0
-			err = handshake.C0S0{}.Read(br)
+			err = handshake.C0S0{}.Read(bc)
 			require.NoError(t, err)
 
 			// S->C handshake S1
 			s1 := handshake.C1S1{}
-			err = s1.Read(br, false)
+			err = s1.Read(bc, false)
 			require.NoError(t, err)
 
 			// S->C handshake S2
-			err = (&handshake.C2S2{Digest: c1.Digest}).Read(br)
+			err = (&handshake.C2S2{Digest: c1.Digest}).Read(bc)
 			require.NoError(t, err)
 
 			// C->S handshake C2
 			err = handshake.C2S2{Digest: s1.Digest}.Write(conn)
 			require.NoError(t, err)
 
-			mw := message.NewWriter(conn)
-			mr := message.NewReader(br)
+			mrw := message.NewReadWriter(bc)
 
 			// C->S connect
-			err = mw.Write(&message.MsgCommandAMF0{
+			err = mrw.Write(&message.MsgCommandAMF0{
 				ChunkStreamID: 3,
 				Payload: []interface{}{
 					"connect",
@@ -166,14 +165,14 @@ func TestReadTracks(t *testing.T) {
 			require.NoError(t, err)
 
 			// S->C window acknowledgement size
-			msg, err := mr.Read()
+			msg, err := mrw.Read()
 			require.NoError(t, err)
 			require.Equal(t, &message.MsgSetWindowAckSize{
 				Value: 2500000,
 			}, msg)
 
 			// S->C set peer bandwidth
-			msg, err = mr.Read()
+			msg, err = mrw.Read()
 			require.NoError(t, err)
 			require.Equal(t, &message.MsgSetPeerBandwidth{
 				Value: 2500000,
@@ -181,16 +180,14 @@ func TestReadTracks(t *testing.T) {
 			}, msg)
 
 			// S->C set chunk size
-			msg, err = mr.Read()
+			msg, err = mrw.Read()
 			require.NoError(t, err)
 			require.Equal(t, &message.MsgSetChunkSize{
 				Value: 65536,
 			}, msg)
 
-			mr.SetChunkSize(65536)
-
 			// S->C result
-			msg, err = mr.Read()
+			msg, err = mrw.Read()
 			require.NoError(t, err)
 			require.Equal(t, &message.MsgCommandAMF0{
 				ChunkStreamID: 3,
@@ -211,15 +208,13 @@ func TestReadTracks(t *testing.T) {
 			}, msg)
 
 			// C->S set chunk size
-			err = mw.Write(&message.MsgSetChunkSize{
+			err = mrw.Write(&message.MsgSetChunkSize{
 				Value: 65536,
 			})
 			require.NoError(t, err)
 
-			mw.SetChunkSize(65536)
-
 			// C->S releaseStream
-			err = mw.Write(&message.MsgCommandAMF0{
+			err = mrw.Write(&message.MsgCommandAMF0{
 				ChunkStreamID: 3,
 				Payload: []interface{}{
 					"releaseStream",
@@ -231,7 +226,7 @@ func TestReadTracks(t *testing.T) {
 			require.NoError(t, err)
 
 			// C->S FCPublish
-			err = mw.Write(&message.MsgCommandAMF0{
+			err = mrw.Write(&message.MsgCommandAMF0{
 				ChunkStreamID: 3,
 				Payload: []interface{}{
 					"FCPublish",
@@ -243,7 +238,7 @@ func TestReadTracks(t *testing.T) {
 			require.NoError(t, err)
 
 			// C->S createStream
-			err = mw.Write(&message.MsgCommandAMF0{
+			err = mrw.Write(&message.MsgCommandAMF0{
 				ChunkStreamID: 3,
 				Payload: []interface{}{
 					"createStream",
@@ -254,7 +249,7 @@ func TestReadTracks(t *testing.T) {
 			require.NoError(t, err)
 
 			// S->C result
-			msg, err = mr.Read()
+			msg, err = mrw.Read()
 			require.NoError(t, err)
 			require.Equal(t, &message.MsgCommandAMF0{
 				ChunkStreamID: 3,
@@ -267,7 +262,7 @@ func TestReadTracks(t *testing.T) {
 			}, msg)
 
 			// C->S publish
-			err = mw.Write(&message.MsgCommandAMF0{
+			err = mrw.Write(&message.MsgCommandAMF0{
 				ChunkStreamID:   8,
 				MessageStreamID: 1,
 				Payload: []interface{}{
@@ -281,7 +276,7 @@ func TestReadTracks(t *testing.T) {
 			require.NoError(t, err)
 
 			// S->C onStatus
-			msg, err = mr.Read()
+			msg, err = mrw.Read()
 			require.NoError(t, err)
 			require.Equal(t, &message.MsgCommandAMF0{
 				ChunkStreamID:   5,
@@ -301,7 +296,7 @@ func TestReadTracks(t *testing.T) {
 			switch ca {
 			case "standard":
 				// C->S metadata
-				err = mw.Write(&message.MsgDataAMF0{
+				err = mrw.Write(&message.MsgDataAMF0{
 					ChunkStreamID:   4,
 					MessageStreamID: 1,
 					Payload: []interface{}{
@@ -341,7 +336,7 @@ func TestReadTracks(t *testing.T) {
 				b := make([]byte, 128)
 				var n int
 				codec.ToConfig(b, &n)
-				err = mw.Write(&message.MsgVideo{
+				err = mrw.Write(&message.MsgVideo{
 					ChunkStreamID:   6,
 					MessageStreamID: 1,
 					IsKeyFrame:      true,
@@ -357,7 +352,7 @@ func TestReadTracks(t *testing.T) {
 					ChannelCount: 2,
 				}.Encode()
 				require.NoError(t, err)
-				err = mw.Write(&message.MsgAudio{
+				err = mrw.Write(&message.MsgAudio{
 					ChunkStreamID:   4,
 					MessageStreamID: 1,
 					Rate:            flvio.SOUND_44Khz,
@@ -370,7 +365,7 @@ func TestReadTracks(t *testing.T) {
 
 			case "metadata without codec id":
 				// C->S metadata
-				err = mw.Write(&message.MsgDataAMF0{
+				err = mrw.Write(&message.MsgDataAMF0{
 					ChunkStreamID:   4,
 					MessageStreamID: 1,
 					Payload: []interface{}{
@@ -406,7 +401,7 @@ func TestReadTracks(t *testing.T) {
 				b := make([]byte, 128)
 				var n int
 				codec.ToConfig(b, &n)
-				err = mw.Write(&message.MsgVideo{
+				err = mrw.Write(&message.MsgVideo{
 					ChunkStreamID:   6,
 					MessageStreamID: 1,
 					IsKeyFrame:      true,
@@ -428,7 +423,7 @@ func TestReadTracks(t *testing.T) {
 				b := make([]byte, 128)
 				var n int
 				codec.ToConfig(b, &n)
-				err = mw.Write(&message.MsgVideo{
+				err = mrw.Write(&message.MsgVideo{
 					ChunkStreamID:   6,
 					MessageStreamID: 1,
 					IsKeyFrame:      true,
@@ -479,7 +474,7 @@ func TestWriteTracks(t *testing.T) {
 	conn, err := net.Dial("tcp", "127.0.0.1:9121")
 	require.NoError(t, err)
 	defer conn.Close()
-	br := bufio.NewReader(conn)
+	bc := bytecounter.NewReadWriter(conn)
 
 	// C->S handshake C0
 	err = handshake.C0S0{}.Write(conn)
@@ -491,27 +486,26 @@ func TestWriteTracks(t *testing.T) {
 	require.NoError(t, err)
 
 	// S->C handshake S0
-	err = handshake.C0S0{}.Read(br)
+	err = handshake.C0S0{}.Read(bc)
 	require.NoError(t, err)
 
 	// S->C handshake S1
 	s1 := handshake.C1S1{}
-	err = s1.Read(br, false)
+	err = s1.Read(bc, false)
 	require.NoError(t, err)
 
 	// S->C handshake S2
-	err = (&handshake.C2S2{Digest: c1.Digest}).Read(br)
+	err = (&handshake.C2S2{Digest: c1.Digest}).Read(bc)
 	require.NoError(t, err)
 
 	// C->S handshake C2
 	err = handshake.C2S2{Digest: s1.Digest}.Write(conn)
 	require.NoError(t, err)
 
-	mw := message.NewWriter(conn)
-	mr := message.NewReader(br)
+	mrw := message.NewReadWriter(bc)
 
 	// C->S connect
-	err = mw.Write(&message.MsgCommandAMF0{
+	err = mrw.Write(&message.MsgCommandAMF0{
 		ChunkStreamID: 3,
 		Payload: []interface{}{
 			"connect",
@@ -531,14 +525,14 @@ func TestWriteTracks(t *testing.T) {
 	require.NoError(t, err)
 
 	// S->C window acknowledgement size
-	msg, err := mr.Read()
+	msg, err := mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgSetWindowAckSize{
 		Value: 2500000,
 	}, msg)
 
 	// S->C set peer bandwidth
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgSetPeerBandwidth{
 		Value: 2500000,
@@ -546,16 +540,14 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// S->C set chunk size
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgSetChunkSize{
 		Value: 65536,
 	}, msg)
 
-	mr.SetChunkSize(65536)
-
 	// S->C result
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgCommandAMF0{
 		ChunkStreamID: 3,
@@ -576,21 +568,19 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// C->S window acknowledgement size
-	err = mw.Write(&message.MsgSetWindowAckSize{
+	err = mrw.Write(&message.MsgSetWindowAckSize{
 		Value: 2500000,
 	})
 	require.NoError(t, err)
 
 	// C->S set chunk size
-	err = mw.Write(&message.MsgSetChunkSize{
+	err = mrw.Write(&message.MsgSetChunkSize{
 		Value: 65536,
 	})
 	require.NoError(t, err)
 
-	mw.SetChunkSize(65536)
-
 	// C->S createStream
-	err = mw.Write(&message.MsgCommandAMF0{
+	err = mrw.Write(&message.MsgCommandAMF0{
 		ChunkStreamID: 3,
 		Payload: []interface{}{
 			"createStream",
@@ -601,7 +591,7 @@ func TestWriteTracks(t *testing.T) {
 	require.NoError(t, err)
 
 	// S->C result
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgCommandAMF0{
 		ChunkStreamID: 3,
@@ -614,7 +604,7 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// C->S getStreamLength
-	err = mw.Write(&message.MsgCommandAMF0{
+	err = mrw.Write(&message.MsgCommandAMF0{
 		ChunkStreamID: 8,
 		Payload: []interface{}{
 			"getStreamLength",
@@ -626,7 +616,7 @@ func TestWriteTracks(t *testing.T) {
 	require.NoError(t, err)
 
 	// C->S play
-	err = mw.Write(&message.MsgCommandAMF0{
+	err = mrw.Write(&message.MsgCommandAMF0{
 		ChunkStreamID: 8,
 		Payload: []interface{}{
 			"play",
@@ -639,21 +629,21 @@ func TestWriteTracks(t *testing.T) {
 	require.NoError(t, err)
 
 	// S->C event "stream is recorded"
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgUserControlStreamIsRecorded{
 		StreamID: 1,
 	}, msg)
 
 	// S->C event "stream begin 1"
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgUserControlStreamBegin{
 		StreamID: 1,
 	}, msg)
 
 	// S->C onStatus
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgCommandAMF0{
 		ChunkStreamID:   5,
@@ -671,7 +661,7 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// S->C onStatus
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgCommandAMF0{
 		ChunkStreamID:   5,
@@ -689,7 +679,7 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// S->C onStatus
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgCommandAMF0{
 		ChunkStreamID:   5,
@@ -707,7 +697,7 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// S->C onStatus
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgCommandAMF0{
 		ChunkStreamID:   5,
@@ -725,7 +715,7 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// S->C onMetadata
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgDataAMF0{
 		ChunkStreamID:   4,
@@ -742,7 +732,7 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// S->C H264 decoder config
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgVideo{
 		ChunkStreamID:   6,
@@ -760,7 +750,7 @@ func TestWriteTracks(t *testing.T) {
 	}, msg)
 
 	// S->C AAC decoder config
-	msg, err = mr.Read()
+	msg, err = mrw.Read()
 	require.NoError(t, err)
 	require.Equal(t, &message.MsgAudio{
 		ChunkStreamID:   4,

internal/rtmp/handshake/c0s0.go

@@ -1,7 +1,6 @@
 package handshake
 
 import (
-	"bufio"
 	"fmt"
 	"io"
 )
@@ -14,7 +13,7 @@ const (
 type C0S0 struct{}
 
 // Read reads a C0S0.
-func (C0S0) Read(r *bufio.Reader) error {
+func (C0S0) Read(r io.Reader) error {
 	buf := make([]byte, 1)
 	_, err := io.ReadFull(r, buf)
 	if err != nil {

internal/rtmp/handshake/c0s0_test.go

@@ -1,7 +1,6 @@
 package handshake
 
 import (
-	"bufio"
 	"bytes"
 	"testing"
 
@@ -14,7 +13,7 @@ var c0s0dec = C0S0{}
 
 func TestC0S0Read(t *testing.T) {
 	var c0s0 C0S0
-	err := c0s0.Read(bufio.NewReader(bytes.NewReader(c0s0enc)))
+	err := c0s0.Read((bytes.NewReader(c0s0enc)))
 	require.NoError(t, err)
 	require.Equal(t, c0s0dec, c0s0)
 }

internal/rtmp/handshake/c1s1.go

@@ -1,7 +1,6 @@
 package handshake
 
 import (
-	"bufio"
 	"bytes"
 	"crypto/hmac"
 	"crypto/rand"
@@ -79,7 +78,7 @@ type C1S1 struct {
 }
 
 // Read reads a C1S1.
-func (c *C1S1) Read(r *bufio.Reader, isC1 bool) error {
+func (c *C1S1) Read(r io.Reader, isC1 bool) error {
 	buf := make([]byte, 1536)
 	_, err := io.ReadFull(r, buf)
 	if err != nil {

internal/rtmp/handshake/c1s1_test.go

@@ -1,7 +1,6 @@
 package handshake
 
 import (
-	"bufio"
 	"bytes"
 	"testing"
 
@@ -44,7 +43,7 @@ func TestC1S1Read(t *testing.T) {
 	)
 
 	var c1s1 C1S1
-	err := c1s1.Read(bufio.NewReader(bytes.NewReader(c1s1enc)), true)
+	err := c1s1.Read((bytes.NewReader(c1s1enc)), true)
 	require.NoError(t, err)
 	require.Equal(t, c1s1dec, c1s1)
 }

internal/rtmp/handshake/c2s2.go

@@ -1,7 +1,6 @@
 package handshake
 
 import (
-	"bufio"
 	"bytes"
 	"crypto/rand"
 	"encoding/binary"
@@ -18,7 +17,7 @@ type C2S2 struct {
 }
 
 // Read reads a C2S2.
-func (c *C2S2) Read(r *bufio.Reader) error {
+func (c *C2S2) Read(r io.Reader) error {
 	buf := make([]byte, 1536)
 	_, err := io.ReadFull(r, buf)
 	if err != nil {

internal/rtmp/handshake/c2s2_test.go

@@ -1,7 +1,6 @@
 package handshake
 
 import (
-	"bufio"
 	"bytes"
 	"testing"
 
@@ -43,7 +42,7 @@ func TestC2S2Read(t *testing.T) {
 
 	var c2s2 C2S2
 	c2s2.Digest = c2s2dec.Digest
-	err := c2s2.Read(bufio.NewReader(bytes.NewReader(c2s2enc)))
+	err := c2s2.Read((bytes.NewReader(c2s2enc)))
 	require.NoError(t, err)
 	require.Equal(t, c2s2dec, c2s2)
 }

internal/rtmp/message/msg_acknowledge.go

@@ -0,0 +1,40 @@
+package message
+
+import (
+	"encoding/binary"
+	"fmt"
+
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/chunk"
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/rawmessage"
+)
+
+// MsgAcknowledge is an acknowledgement message.
+type MsgAcknowledge struct {
+	Value uint32
+}
+
+// Unmarshal implements Message.
+func (m *MsgAcknowledge) Unmarshal(raw *rawmessage.Message) error {
+	if raw.ChunkStreamID != ControlChunkStreamID {
+		return fmt.Errorf("unexpected chunk stream ID")
+	}
+
+	if len(raw.Body) != 4 {
+		return fmt.Errorf("unexpected body size")
+	}
+
+	m.Value = binary.BigEndian.Uint32(raw.Body)
+	return nil
+}
+
+// Marshal implements Message.
+func (m *MsgAcknowledge) Marshal() (*rawmessage.Message, error) {
+	body := make([]byte, 4)
+	binary.BigEndian.PutUint32(body, m.Value)
+
+	return &rawmessage.Message{
+		ChunkStreamID: ControlChunkStreamID,
+		Type:          chunk.MessageTypeAcknowledge,
+		Body:          body,
+	}, nil
+}

internal/rtmp/message/reader.go

@@ -1,10 +1,10 @@
 package message
 
 import (
-	"bufio"
 	"encoding/binary"
 	"fmt"
 
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/chunk"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/rawmessage"
 )
@@ -14,6 +14,9 @@ func allocateMessage(raw *rawmessage.Message) (Message, error) {
 	case chunk.MessageTypeSetChunkSize:
 		return &MsgSetChunkSize{}, nil
 
+	case chunk.MessageTypeAcknowledge:
+		return &MsgAcknowledge{}, nil
+
 	case chunk.MessageTypeSetWindowAckSize:
 		return &MsgSetWindowAckSize{}, nil
 
@@ -75,18 +78,13 @@ type Reader struct {
 }
 
 // NewReader allocates a Reader.
-func NewReader(r *bufio.Reader) *Reader {
+func NewReader(r *bytecounter.Reader, onAckNeeded func(uint32) error) *Reader {
 	return &Reader{
-		r: rawmessage.NewReader(r),
+		r: rawmessage.NewReader(r, onAckNeeded),
 	}
 }
 
-// SetChunkSize sets the maximum chunk size.
-func (r *Reader) SetChunkSize(v int) {
-	r.r.SetChunkSize(v)
-}
-
-// Read reads a essage.
+// Read reads a Message.
 func (r *Reader) Read() (Message, error) {
 	raw, err := r.r.Read()
 	if err != nil {
@@ -103,5 +101,13 @@ func (r *Reader) Read() (Message, error) {
 		return nil, err
 	}
 
+	switch tmsg := msg.(type) {
+	case *MsgSetChunkSize:
+		r.r.SetChunkSize(tmsg.Value)
+
+	case *MsgSetWindowAckSize:
+		r.r.SetWindowAckSize(tmsg.Value)
+	}
+
 	return msg, nil
 }

internal/rtmp/message/readwriter.go

@@ -0,0 +1,46 @@
+package message
+
+import (
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
+)
+
+// ReadWriter is a message reader/writer.
+type ReadWriter struct {
+	r *Reader
+	w *Writer
+}
+
+// NewReadWriter allocates a ReadWriter.
+func NewReadWriter(bc *bytecounter.ReadWriter) *ReadWriter {
+	w := NewWriter(bc.Writer)
+
+	r := NewReader(bc.Reader, func(count uint32) error {
+		return w.Write(&MsgAcknowledge{
+			Value: (count),
+		})
+	})
+
+	return &ReadWriter{
+		r: r,
+		w: w,
+	}
+}
+
+// Read reads a message.
+func (rw *ReadWriter) Read() (Message, error) {
+	msg, err := rw.r.Read()
+	if err != nil {
+		return nil, err
+	}
+
+	if tmsg, ok := msg.(*MsgAcknowledge); ok {
+		rw.w.SetAcknowledgeValue(tmsg.Value)
+	}
+
+	return msg, nil
+}
+
+// Write writes a message.
+func (rw *ReadWriter) Write(msg Message) error {
+	return rw.w.Write(msg)
+}

internal/rtmp/message/writer.go

@@ -1,8 +1,7 @@
 package message
 
 import (
-	"io"
-
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/rawmessage"
 )
 
@@ -12,23 +11,36 @@ type Writer struct {
 }
 
 // NewWriter allocates a Writer.
-func NewWriter(w io.Writer) *Writer {
+func NewWriter(w *bytecounter.Writer) *Writer {
 	return &Writer{
 		w: rawmessage.NewWriter(w),
 	}
 }
 
-// SetChunkSize sets the maximum chunk size.
-func (mw *Writer) SetChunkSize(v int) {
-	mw.w.SetChunkSize(v)
+// SetAcknowledgeValue sets the value of the last received acknowledge.
+func (w *Writer) SetAcknowledgeValue(v uint32) {
+	w.w.SetAcknowledgeValue(v)
 }
 
 // Write writes a message.
-func (mw *Writer) Write(msg Message) error {
+func (w *Writer) Write(msg Message) error {
 	raw, err := msg.Marshal()
 	if err != nil {
 		return err
 	}
 
-	return mw.w.Write(raw)
+	err = w.w.Write(raw)
+	if err != nil {
+		return err
+	}
+
+	switch tmsg := msg.(type) {
+	case *MsgSetChunkSize:
+		w.w.SetChunkSize(tmsg.Value)
+
+	case *MsgSetWindowAckSize:
+		w.w.SetWindowAckSize(tmsg.Value)
+	}
+
+	return nil
 }

internal/rtmp/rawmessage/reader.go

@@ -1,10 +1,10 @@
 package rawmessage
 
 import (
-	"bufio"
 	"errors"
 	"fmt"
 
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/chunk"
 )
 
@@ -20,7 +20,32 @@ type readerChunkStream struct {
 	curTimestampDelta  *uint32
 }
 
-func (rc *readerChunkStream) read(typ byte) (*Message, error) {
+func (rc *readerChunkStream) readChunk(c chunk.Chunk, chunkBodySize uint32) error {
+	err := c.Read(rc.mr.r, chunkBodySize)
+	if err != nil {
+		return err
+	}
+
+	// check if an ack is needed
+	if rc.mr.ackWindowSize != 0 {
+		count := rc.mr.r.Count()
+		diff := count - rc.mr.lastAckCount
+		// TODO: handle overflow
+
+		if diff > (rc.mr.ackWindowSize) {
+			err := rc.mr.onAckNeeded(count)
+			if err != nil {
+				return err
+			}
+
+			rc.mr.lastAckCount += (rc.mr.ackWindowSize)
+		}
+	}
+
+	return nil
+}
+
+func (rc *readerChunkStream) readMessage(typ byte) (*Message, error) {
 	switch typ {
 	case 0:
 		if rc.curBody != nil {
@@ -28,7 +53,7 @@ func (rc *readerChunkStream) read(typ byte) (*Message, error) {
 		}
 
 		var c0 chunk.Chunk0
-		err := c0.Read(rc.mr.r, rc.mr.chunkSize)
+		err := rc.readChunk(&c0, rc.mr.chunkSize)
 		if err != nil {
 			return nil, err
 		}
@@ -65,7 +90,7 @@ func (rc *readerChunkStream) read(typ byte) (*Message, error) {
 		}
 
 		var c1 chunk.Chunk1
-		err := c1.Read(rc.mr.r, rc.mr.chunkSize)
+		err := rc.readChunk(&c1, rc.mr.chunkSize)
 		if err != nil {
 			return nil, err
 		}
@@ -100,13 +125,13 @@ func (rc *readerChunkStream) read(typ byte) (*Message, error) {
 			return nil, fmt.Errorf("received type 2 chunk but expected type 3 chunk")
 		}
 
-		chunkBodyLen := int(*rc.curBodyLen)
+		chunkBodyLen := (*rc.curBodyLen)
 		if chunkBodyLen > rc.mr.chunkSize {
 			chunkBodyLen = rc.mr.chunkSize
 		}
 
 		var c2 chunk.Chunk2
-		err := c2.Read(rc.mr.r, chunkBodyLen)
+		err := rc.readChunk(&c2, chunkBodyLen)
 		if err != nil {
 			return nil, err
 		}
@@ -116,7 +141,7 @@ func (rc *readerChunkStream) read(typ byte) (*Message, error) {
 		v2 := c2.TimestampDelta
 		rc.curTimestampDelta = &v2
 
-		if chunkBodyLen != len(c2.Body) {
+		if chunkBodyLen != uint32(len(c2.Body)) {
 			rc.curBody = &c2.Body
 			return nil, errMoreChunksNeeded
 		}
@@ -134,13 +159,13 @@ func (rc *readerChunkStream) read(typ byte) (*Message, error) {
 		}
 
 		if rc.curBody != nil {
-			chunkBodyLen := int(*rc.curBodyLen) - len(*rc.curBody)
+			chunkBodyLen := (*rc.curBodyLen) - uint32(len(*rc.curBody))
 			if chunkBodyLen > rc.mr.chunkSize {
 				chunkBodyLen = rc.mr.chunkSize
 			}
 
 			var c3 chunk.Chunk3
-			err := c3.Read(rc.mr.r, chunkBodyLen)
+			err := rc.readChunk(&c3, chunkBodyLen)
 			if err != nil {
 				return nil, err
 			}
@@ -162,13 +187,13 @@ func (rc *readerChunkStream) read(typ byte) (*Message, error) {
 			}, nil
 		}
 
-		chunkBodyLen := int(*rc.curBodyLen)
+		chunkBodyLen := (*rc.curBodyLen)
 		if chunkBodyLen > rc.mr.chunkSize {
 			chunkBodyLen = rc.mr.chunkSize
 		}
 
 		var c3 chunk.Chunk3
-		err := c3.Read(rc.mr.r, chunkBodyLen)
+		err := rc.readChunk(&c3, chunkBodyLen)
 		if err != nil {
 			return nil, err
 		}
@@ -187,25 +212,35 @@ func (rc *readerChunkStream) read(typ byte) (*Message, error) {
 
 // Reader is a raw message reader.
 type Reader struct {
-	r            *bufio.Reader
-	chunkSize    int
+	r           *bytecounter.Reader
+	onAckNeeded func(uint32) error
+
+	chunkSize     uint32
+	ackWindowSize uint32
+	lastAckCount  uint32
 	chunkStreams  map[byte]*readerChunkStream
 }
 
 // NewReader allocates a Reader.
-func NewReader(r *bufio.Reader) *Reader {
+func NewReader(r *bytecounter.Reader, onAckNeeded func(uint32) error) *Reader {
 	return &Reader{
 		r:            r,
+		onAckNeeded:  onAckNeeded,
 		chunkSize:    128,
 		chunkStreams: make(map[byte]*readerChunkStream),
 	}
 }
 
 // SetChunkSize sets the maximum chunk size.
-func (r *Reader) SetChunkSize(v int) {
+func (r *Reader) SetChunkSize(v uint32) {
 	r.chunkSize = v
 }
 
+// SetWindowAckSize sets the window acknowledgement size.
+func (r *Reader) SetWindowAckSize(v uint32) {
+	r.ackWindowSize = v
+}
+
 // Read reads a Message.
 func (r *Reader) Read() (*Message, error) {
 	for {
@@ -225,7 +260,7 @@ func (r *Reader) Read() (*Message, error) {
 
 		r.r.UnreadByte()
 
-		msg, err := rc.read(typ)
+		msg, err := rc.readMessage(typ)
 		if err != nil {
 			if err == errMoreChunksNeeded {
 				continue

internal/rtmp/rawmessage/reader_test.go

@@ -1,12 +1,13 @@
 package rawmessage
 
 import (
-	"bufio"
 	"bytes"
 	"testing"
 
-	"github.com/aler9/rtsp-simple-server/internal/rtmp/chunk"
 	"github.com/stretchr/testify/require"
+
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/chunk"
 )
 
 type writableChunk interface {
@@ -21,7 +22,10 @@ type sequenceEntry struct {
 func TestReader(t *testing.T) {
 	testSequence := func(t *testing.T, seq []sequenceEntry) {
 		var buf bytes.Buffer
-		r := NewReader(bufio.NewReader(&buf))
+		bcr := bytecounter.NewReader(&buf)
+		r := NewReader(bcr, func(count uint32) error {
+			return nil
+		})
 
 		for _, entry := range seq {
 			buf2, err := entry.chunk.Write()
@@ -122,7 +126,10 @@ func TestReader(t *testing.T) {
 
 	t.Run("chunk0 + chunk3", func(t *testing.T) {
 		var buf bytes.Buffer
-		r := NewReader(bufio.NewReader(&buf))
+		bcr := bytecounter.NewReader(&buf)
+		r := NewReader(bcr, func(count uint32) error {
+			return nil
+		})
 
 		buf2, err := chunk.Chunk0{
 			ChunkStreamID:   27,
@@ -153,3 +160,36 @@ func TestReader(t *testing.T) {
 		}, msg)
 	})
 }
+
+func TestReaderAcknowledge(t *testing.T) {
+	onAckCalled := make(chan struct{})
+
+	var buf bytes.Buffer
+	bcr := bytecounter.NewReader(&buf)
+	r := NewReader(bcr, func(count uint32) error {
+		close(onAckCalled)
+		return nil
+	})
+
+	r.SetWindowAckSize(100)
+
+	for i := 0; i < 2; i++ {
+		buf2, err := chunk.Chunk0{
+			ChunkStreamID:   27,
+			Timestamp:       18576,
+			Type:            chunk.MessageTypeSetPeerBandwidth,
+			MessageStreamID: 3123,
+			BodyLen:         64,
+			Body:            bytes.Repeat([]byte{0x03}, 64),
+		}.Write()
+		require.NoError(t, err)
+		buf.Write(buf2)
+	}
+
+	for i := 0; i < 2; i++ {
+		_, err := r.Read()
+		require.NoError(t, err)
+	}
+
+	<-onAckCalled
+}

internal/rtmp/rawmessage/writer.go

@@ -1,8 +1,9 @@
 package rawmessage
 
 import (
-	"io"
+	"fmt"
 
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/chunk"
 )
 
@@ -10,14 +11,38 @@ type writerChunkStream struct {
 	mw                  *Writer
 	lastMessageStreamID *uint32
 	lastType            *chunk.MessageType
-	lastBodyLen         *int
+	lastBodyLen         *uint32
 	lastTimestamp       *uint32
 	lastTimestampDelta  *uint32
 }
 
-func (wc *writerChunkStream) write(msg *Message) error {
-	bodyLen := len(msg.Body)
-	pos := 0
+func (wc *writerChunkStream) writeChunk(c chunk.Chunk) error {
+	buf, err := c.Write()
+	if err != nil {
+		return err
+	}
+
+	_, err = wc.mw.w.Write(buf)
+	if err != nil {
+		return err
+	}
+
+	// check if we received an acknowledge
+	if wc.mw.ackWindowSize != 0 {
+		diff := wc.mw.w.Count() - (wc.mw.ackValue)
+		// TODO: handle overflow
+
+		if diff > (wc.mw.ackWindowSize * 3 / 2) {
+			return fmt.Errorf("no acknowledge received within window")
+		}
+	}
+
+	return nil
+}
+
+func (wc *writerChunkStream) writeMessage(msg *Message) error {
+	bodyLen := uint32(len(msg.Body))
+	pos := uint32(0)
 	firstChunk := true
 
 	var timestampDelta *uint32
@@ -42,65 +67,45 @@ func (wc *writerChunkStream) write(msg *Message) error {
 
 			switch {
 			case wc.lastMessageStreamID == nil || timestampDelta == nil || *wc.lastMessageStreamID != msg.MessageStreamID:
-				buf, err := chunk.Chunk0{
+				err := wc.writeChunk(&chunk.Chunk0{
 					ChunkStreamID:   msg.ChunkStreamID,
 					Timestamp:       msg.Timestamp,
 					Type:            msg.Type,
 					MessageStreamID: msg.MessageStreamID,
-					BodyLen:         uint32(bodyLen),
+					BodyLen:         (bodyLen),
 					Body:            msg.Body[pos : pos+chunkBodyLen],
-				}.Write()
-				if err != nil {
-					return err
-				}
-
-				_, err = wc.mw.w.Write(buf)
+				})
 				if err != nil {
 					return err
 				}
 
 			case *wc.lastType != msg.Type || *wc.lastBodyLen != bodyLen:
-				buf, err := chunk.Chunk1{
+				err := wc.writeChunk(&chunk.Chunk1{
 					ChunkStreamID:  msg.ChunkStreamID,
 					TimestampDelta: *timestampDelta,
 					Type:           msg.Type,
-					BodyLen:        uint32(bodyLen),
+					BodyLen:        (bodyLen),
 					Body:           msg.Body[pos : pos+chunkBodyLen],
-				}.Write()
-				if err != nil {
-					return err
-				}
-
-				_, err = wc.mw.w.Write(buf)
+				})
 				if err != nil {
 					return err
 				}
 
 			case wc.lastTimestampDelta == nil || *wc.lastTimestampDelta != *timestampDelta:
-				buf, err := chunk.Chunk2{
+				err := wc.writeChunk(&chunk.Chunk2{
 					ChunkStreamID:  msg.ChunkStreamID,
 					TimestampDelta: *timestampDelta,
 					Body:           msg.Body[pos : pos+chunkBodyLen],
-				}.Write()
-				if err != nil {
-					return err
-				}
-
-				_, err = wc.mw.w.Write(buf)
+				})
 				if err != nil {
 					return err
 				}
 
 			default:
-				buf, err := chunk.Chunk3{
+				err := wc.writeChunk(&chunk.Chunk3{
 					ChunkStreamID: msg.ChunkStreamID,
 					Body:          msg.Body[pos : pos+chunkBodyLen],
-				}.Write()
-				if err != nil {
-					return err
-				}
-
-				_, err = wc.mw.w.Write(buf)
+				})
 				if err != nil {
 					return err
 				}
@@ -120,15 +125,10 @@ func (wc *writerChunkStream) write(msg *Message) error {
 				wc.lastTimestampDelta = &v5
 			}
 		} else {
-			buf, err := chunk.Chunk3{
+			err := wc.writeChunk(&chunk.Chunk3{
 				ChunkStreamID: msg.ChunkStreamID,
 				Body:          msg.Body[pos : pos+chunkBodyLen],
-			}.Write()
-			if err != nil {
-				return err
-			}
-
-			_, err = wc.mw.w.Write(buf)
+			})
 			if err != nil {
 				return err
 			}
@@ -144,13 +144,15 @@ func (wc *writerChunkStream) write(msg *Message) error {
 
 // Writer is a raw message writer.
 type Writer struct {
-	w            io.Writer
-	chunkSize    int
+	w             *bytecounter.Writer
+	chunkSize     uint32
+	ackWindowSize uint32
+	ackValue      uint32
 	chunkStreams  map[byte]*writerChunkStream
 }
 
 // NewWriter allocates a Writer.
-func NewWriter(w io.Writer) *Writer {
+func NewWriter(w *bytecounter.Writer) *Writer {
 	return &Writer{
 		w:            w,
 		chunkSize:    128,
@@ -159,10 +161,20 @@ func NewWriter(w io.Writer) *Writer {
 }
 
 // SetChunkSize sets the maximum chunk size.
-func (w *Writer) SetChunkSize(v int) {
+func (w *Writer) SetChunkSize(v uint32) {
 	w.chunkSize = v
 }
 
+// SetWindowAckSize sets the window acknowledgement size.
+func (w *Writer) SetWindowAckSize(v uint32) {
+	w.ackWindowSize = v
+}
+
+// SetAcknowledgeValue sets the acknowledge sequence number.
+func (w *Writer) SetAcknowledgeValue(v uint32) {
+	w.ackValue = v
+}
+
 // Write writes a Message.
 func (w *Writer) Write(msg *Message) error {
 	wc, ok := w.chunkStreams[msg.ChunkStreamID]
@@ -171,5 +183,5 @@ func (w *Writer) Write(msg *Message) error {
 		w.chunkStreams[msg.ChunkStreamID] = wc
 	}
 
-	return wc.write(msg)
+	return wc.writeMessage(msg)
 }

internal/rtmp/rawmessage/writer_test.go

@@ -1,10 +1,10 @@
 package rawmessage
 
 import (
-	"bufio"
 	"bytes"
 	"testing"
 
+	"github.com/aler9/rtsp-simple-server/internal/rtmp/bytecounter"
 	"github.com/aler9/rtsp-simple-server/internal/rtmp/chunk"
 	"github.com/stretchr/testify/require"
 )
@@ -12,8 +12,7 @@ import (
 func TestWriter(t *testing.T) {
 	t.Run("chunk0 + chunk1", func(t *testing.T) {
 		var buf bytes.Buffer
-		br := bufio.NewReader(&buf)
-		w := NewWriter(&buf)
+		w := NewWriter(bytecounter.NewWriter(&buf))
 
 		err := w.Write(&Message{
 			ChunkStreamID:   27,
@@ -25,7 +24,7 @@ func TestWriter(t *testing.T) {
 		require.NoError(t, err)
 
 		var c0 chunk.Chunk0
-		err = c0.Read(br, 128)
+		err = c0.Read(&buf, 128)
 		require.NoError(t, err)
 		require.Equal(t, chunk.Chunk0{
 			ChunkStreamID:   27,
@@ -46,7 +45,7 @@ func TestWriter(t *testing.T) {
 		require.NoError(t, err)
 
 		var c1 chunk.Chunk1
-		err = c1.Read(br, 128)
+		err = c1.Read(&buf, 128)
 		require.NoError(t, err)
 		require.Equal(t, chunk.Chunk1{
 			ChunkStreamID:  27,
@@ -59,8 +58,7 @@ func TestWriter(t *testing.T) {
 
 	t.Run("chunk0 + chunk2 + chunk3", func(t *testing.T) {
 		var buf bytes.Buffer
-		br := bufio.NewReader(&buf)
-		w := NewWriter(&buf)
+		w := NewWriter(bytecounter.NewWriter(&buf))
 
 		err := w.Write(&Message{
 			ChunkStreamID:   27,
@@ -72,7 +70,7 @@ func TestWriter(t *testing.T) {
 		require.NoError(t, err)
 
 		var c0 chunk.Chunk0
-		err = c0.Read(br, 128)
+		err = c0.Read(&buf, 128)
 		require.NoError(t, err)
 		require.Equal(t, chunk.Chunk0{
 			ChunkStreamID:   27,
@@ -93,7 +91,7 @@ func TestWriter(t *testing.T) {
 		require.NoError(t, err)
 
 		var c2 chunk.Chunk2
-		err = c2.Read(br, 64)
+		err = c2.Read(&buf, 64)
 		require.NoError(t, err)
 		require.Equal(t, chunk.Chunk2{
 			ChunkStreamID:  27,
@@ -111,7 +109,7 @@ func TestWriter(t *testing.T) {
 		require.NoError(t, err)
 
 		var c3 chunk.Chunk3
-		err = c3.Read(br, 64)
+		err = c3.Read(&buf, 64)
 		require.NoError(t, err)
 		require.Equal(t, chunk.Chunk3{
 			ChunkStreamID: 27,
@@ -121,8 +119,7 @@ func TestWriter(t *testing.T) {
 
 	t.Run("chunk0 + chunk3", func(t *testing.T) {
 		var buf bytes.Buffer
-		br := bufio.NewReader(&buf)
-		w := NewWriter(&buf)
+		w := NewWriter(bytecounter.NewWriter(&buf))
 
 		err := w.Write(&Message{
 			ChunkStreamID:   27,
@@ -134,7 +131,7 @@ func TestWriter(t *testing.T) {
 		require.NoError(t, err)
 
 		var c0 chunk.Chunk0
-		err = c0.Read(br, 128)
+		err = c0.Read(&buf, 128)
 		require.NoError(t, err)
 		require.Equal(t, chunk.Chunk0{
 			ChunkStreamID:   27,
@@ -146,7 +143,7 @@ func TestWriter(t *testing.T) {
 		}, c0)
 
 		var c3 chunk.Chunk3
-		err = c3.Read(br, 64)
+		err = c3.Read(&buf, 64)
 		require.NoError(t, err)
 		require.Equal(t, chunk.Chunk3{
 			ChunkStreamID: 27,
@@ -154,3 +151,30 @@ func TestWriter(t *testing.T) {
 		}, c3)
 	})
 }
+
+func TestWriterAcknowledge(t *testing.T) {
+	var buf bytes.Buffer
+	w := NewWriter(bytecounter.NewWriter(&buf))
+
+	w.SetWindowAckSize(100)
+
+	for i := 0; i < 2; i++ {
+		err := w.Write(&Message{
+			ChunkStreamID:   27,
+			Timestamp:       18576,
+			Type:            chunk.MessageTypeSetPeerBandwidth,
+			MessageStreamID: 3123,
+			Body:            bytes.Repeat([]byte{0x03}, 64),
+		})
+		require.NoError(t, err)
+	}
+
+	err := w.Write(&Message{
+		ChunkStreamID:   27,
+		Timestamp:       18576,
+		Type:            chunk.MessageTypeSetPeerBandwidth,
+		MessageStreamID: 3123,
+		Body:            bytes.Repeat([]byte{0x03}, 64),
+	})
+	require.EqualError(t, err, "no acknowledge received within window")
+}