buffer, channel, more transport constants

2024-12-31 17:02:51 -06:00
parent 8df4039b18
commit 54c401e2a5
3 changed files with 530 additions and 2 deletions
--- a/pkg/buffer/buffer.go
+++ b/pkg/buffer/buffer.go
@@ -0,0 +1,240 @@
+package buffer
+
+import (
+	"bufio"
+	"bytes"
+	"compress/bzip2"
+	"encoding/binary"
+	"io"
+	"sync"
+
+	"github.com/Sudo-Ivan/reticulum-go/pkg/channel"
+)
+
+const (
+	StreamIDMax   = 0x3fff // 16383
+	MaxChunkLen   = 16 * 1024
+	MaxDataLen    = 457 // MDU - 2 - 6 (2 for stream header, 6 for channel envelope)
+	CompressTries = 4
+)
+
+type StreamDataMessage struct {
+	StreamID   uint16
+	Data       []byte
+	EOF        bool
+	Compressed bool
+}
+
+func (m *StreamDataMessage) Pack() ([]byte, error) {
+	headerVal := uint16(m.StreamID & StreamIDMax)
+	if m.EOF {
+		headerVal |= 0x8000
+	}
+	if m.Compressed {
+		headerVal |= 0x4000
+	}
+
+	buf := new(bytes.Buffer)
+	binary.Write(buf, binary.BigEndian, headerVal)
+	buf.Write(m.Data)
+	return buf.Bytes(), nil
+}
+
+func (m *StreamDataMessage) GetType() uint16 {
+	return 0x01 // Assign appropriate message type constant
+}
+
+func (m *StreamDataMessage) Unpack(data []byte) error {
+	if len(data) < 2 {
+		return io.ErrShortBuffer
+	}
+
+	header := binary.BigEndian.Uint16(data[:2])
+	m.StreamID = header & StreamIDMax
+	m.EOF = (header & 0x8000) != 0
+	m.Compressed = (header & 0x4000) != 0
+	m.Data = data[2:]
+
+	return nil
+}
+
+type RawChannelReader struct {
+	streamID  int
+	channel   *channel.Channel
+	buffer    *bytes.Buffer
+	eof       bool
+	callbacks []func(int)
+	mutex     sync.RWMutex
+}
+
+func NewRawChannelReader(streamID int, ch *channel.Channel) *RawChannelReader {
+	reader := &RawChannelReader{
+		streamID:  streamID,
+		channel:   ch,
+		buffer:    bytes.NewBuffer(nil),
+		callbacks: make([]func(int), 0),
+	}
+	
+	ch.AddMessageHandler(reader.HandleMessage)
+	return reader
+}
+
+func (r *RawChannelReader) AddReadyCallback(cb func(int)) {
+	r.mutex.Lock()
+	defer r.mutex.Unlock()
+	r.callbacks = append(r.callbacks, cb)
+}
+
+func (r *RawChannelReader) RemoveReadyCallback(cb func(int)) {
+	r.mutex.Lock()
+	defer r.mutex.Unlock()
+	for i, fn := range r.callbacks {
+		if &fn == &cb {
+			r.callbacks = append(r.callbacks[:i], r.callbacks[i+1:]...)
+			break
+		}
+	}
+}
+
+func (r *RawChannelReader) Read(p []byte) (n int, err error) {
+	r.mutex.Lock()
+	defer r.mutex.Unlock()
+
+	if r.buffer.Len() == 0 && r.eof {
+		return 0, io.EOF
+	}
+
+	n, err = r.buffer.Read(p)
+	if err == io.EOF && !r.eof {
+		err = nil
+	}
+	return
+}
+
+func (r *RawChannelReader) HandleMessage(msg channel.MessageBase) bool {
+	if streamMsg, ok := msg.(*StreamDataMessage); ok && streamMsg.StreamID == uint16(r.streamID) {
+		r.mutex.Lock()
+		defer r.mutex.Unlock()
+
+		if streamMsg.Compressed {
+			decompressed := decompressData(streamMsg.Data)
+			r.buffer.Write(decompressed)
+		} else {
+			r.buffer.Write(streamMsg.Data)
+		}
+
+		if streamMsg.EOF {
+			r.eof = true
+		}
+
+		// Notify callbacks
+		for _, cb := range r.callbacks {
+			cb(r.buffer.Len())
+		}
+
+		return true
+	}
+	return false
+}
+
+type RawChannelWriter struct {
+	streamID int
+	channel  *channel.Channel
+	eof      bool
+}
+
+func NewRawChannelWriter(streamID int, ch *channel.Channel) *RawChannelWriter {
+	return &RawChannelWriter{
+		streamID: streamID,
+		channel:  ch,
+	}
+}
+
+func (w *RawChannelWriter) Write(p []byte) (n int, err error) {
+	if len(p) > MaxChunkLen {
+		p = p[:MaxChunkLen]
+	}
+
+	msg := &StreamDataMessage{
+		StreamID: uint16(w.streamID),
+		Data:     p,
+		EOF:      w.eof,
+	}
+
+	if len(p) > 32 {
+		for try := 1; try < CompressTries; try++ {
+			chunkLen := len(p) / try
+			compressed := compressData(p[:chunkLen])
+			if len(compressed) < MaxDataLen && len(compressed) < chunkLen {
+				msg.Data = compressed
+				msg.Compressed = true
+				break
+			}
+		}
+	}
+
+	if err := w.channel.Send(msg); err != nil {
+		return 0, err
+	}
+
+	return len(p), nil
+}
+
+func (w *RawChannelWriter) Close() error {
+	w.eof = true
+	_, err := w.Write(nil)
+	return err
+}
+
+type Buffer struct {
+	ReadWriter *bufio.ReadWriter
+}
+
+func (b *Buffer) Write(p []byte) (n int, err error) {
+	return b.ReadWriter.Write(p)
+}
+
+func (b *Buffer) Read(p []byte) (n int, err error) {
+	return b.ReadWriter.Read(p)
+}
+
+func (b *Buffer) Close() error {
+	if err := b.ReadWriter.Writer.Flush(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func CreateReader(streamID int, ch *channel.Channel, readyCallback func(int)) *bufio.Reader {
+	raw := NewRawChannelReader(streamID, ch)
+	if readyCallback != nil {
+		raw.AddReadyCallback(readyCallback)
+	}
+	return bufio.NewReader(raw)
+}
+
+func CreateWriter(streamID int, ch *channel.Channel) *bufio.Writer {
+	raw := NewRawChannelWriter(streamID, ch)
+	return bufio.NewWriter(raw)
+}
+
+func CreateBidirectionalBuffer(receiveStreamID, sendStreamID int, ch *channel.Channel, readyCallback func(int)) *bufio.ReadWriter {
+	reader := CreateReader(receiveStreamID, ch, readyCallback)
+	writer := CreateWriter(sendStreamID, ch)
+	return bufio.NewReadWriter(reader, writer)
+}
+
+func compressData(data []byte) []byte {
+	var compressed bytes.Buffer
+	w := bytes.NewBuffer(data)
+	r := bzip2.NewReader(w)
+	io.Copy(&compressed, r)
+	return compressed.Bytes()
+}
+
+func decompressData(data []byte) []byte {
+	reader := bzip2.NewReader(bytes.NewReader(data))
+	var decompressed bytes.Buffer
+	io.Copy(&decompressed, reader)
+	return decompressed.Bytes()
+}