From b2b842cf09d9d0e6f0309c4bb16339f37e5a4ec2 Mon Sep 17 00:00:00 2001
From: zarazaex69 <zarazaex@tuta.io>
Date: Tue, 14 Apr 2026 01:27:39 +0300
Subject: [PATCH] feat(jazz): add protobuf-style packet encoding and decoding
 for datachannel messages

---
 internal/provider/jazz/datapacket.go | 149 +++++++++++++++++++++++++++
 internal/provider/jazz/peer.go       |  39 +++++--
 2 files changed, 181 insertions(+), 7 deletions(-)
 create mode 100644 internal/provider/jazz/datapacket.go

diff --git a/internal/provider/jazz/datapacket.go b/internal/provider/jazz/datapacket.go
new file mode 100644
index 0000000..a89d5ef
--- /dev/null
+++ b/internal/provider/jazz/datapacket.go
@@ -0,0 +1,149 @@
+package jazz
+
+import (
+	"encoding/binary"
+	"io"
+
+	"github.com/google/uuid"
+)
+
+func encodeVarint(value uint64) []byte {
+	buf := make([]byte, binary.MaxVarintLen64)
+	n := binary.PutUvarint(buf, value)
+	return buf[:n]
+}
+
+func encodeField(fieldNumber int, wireType int, data []byte) []byte {
+	tag := encodeVarint(uint64((fieldNumber << 3) | wireType))
+	if wireType == 0 {
+		return append(tag, data...)
+	}
+	if wireType == 2 {
+		length := encodeVarint(uint64(len(data)))
+		result := append(tag, length...)
+		return append(result, data...)
+	}
+	return append(tag, data...)
+}
+
+func EncodeDataPacket(payload []byte) []byte {
+	msgID := uuid.New().String()
+
+	userFields := encodeField(2, 2, payload)
+	userFields = append(userFields, encodeField(8, 2, []byte(msgID))...)
+
+	userPacket := userFields
+
+	dp := encodeField(1, 0, encodeVarint(0))
+	dp = append(dp, encodeField(2, 2, userPacket)...)
+
+	return dp
+}
+
+func readVarint(r io.ByteReader) (uint64, error) {
+	return binary.ReadUvarint(r)
+}
+
+func DecodeDataPacket(raw []byte) ([]byte, bool) {
+	reader := &byteReader{data: raw, pos: 0}
+
+	var userData []byte
+
+	for reader.pos < len(reader.data) {
+		tagVal, err := readVarint(reader)
+		if err != nil {
+			break
+		}
+
+		fieldNumber := int(tagVal >> 3)
+		wireType := int(tagVal & 0x07)
+
+		if wireType == 0 {
+			_, _ = readVarint(reader)
+		} else if wireType == 2 {
+			length, err := readVarint(reader)
+			if err != nil {
+				break
+			}
+			data := make([]byte, length)
+			n, err := reader.Read(data)
+			if err != nil || n != int(length) {
+				break
+			}
+			if fieldNumber == 2 {
+				userData = data
+			}
+		} else if wireType == 1 {
+			reader.pos += 8
+		} else if wireType == 5 {
+			reader.pos += 4
+		} else {
+			break
+		}
+	}
+
+	if userData == nil {
+		return nil, false
+	}
+
+	innerReader := &byteReader{data: userData, pos: 0}
+	var payload []byte
+
+	for innerReader.pos < len(innerReader.data) {
+		tagVal, err := readVarint(innerReader)
+		if err != nil {
+			break
+		}
+
+		fn := int(tagVal >> 3)
+		wt := int(tagVal & 0x07)
+
+		if wt == 0 {
+			_, _ = readVarint(innerReader)
+		} else if wt == 2 {
+			length, err := readVarint(innerReader)
+			if err != nil {
+				break
+			}
+			data := make([]byte, length)
+			n, err := innerReader.Read(data)
+			if err != nil || n != int(length) {
+				break
+			}
+			if fn == 2 {
+				payload = data
+			}
+		} else if wt == 1 {
+			innerReader.pos += 8
+		} else if wt == 5 {
+			innerReader.pos += 4
+		} else {
+			break
+		}
+	}
+
+	return payload, len(payload) > 0
+}
+
+type byteReader struct {
+	data []byte
+	pos  int
+}
+
+func (b *byteReader) ReadByte() (byte, error) {
+	if b.pos >= len(b.data) {
+		return 0, io.EOF
+	}
+	c := b.data[b.pos]
+	b.pos++
+	return c, nil
+}
+
+func (b *byteReader) Read(p []byte) (int, error) {
+	if b.pos >= len(b.data) {
+		return 0, io.EOF
+	}
+	n := copy(p, b.data[b.pos:])
+	b.pos += n
+	return n, nil
+}
diff --git a/internal/provider/jazz/peer.go b/internal/provider/jazz/peer.go
index 555768e..7a126f1 100644
--- a/internal/provider/jazz/peer.go
+++ b/internal/provider/jazz/peer.go
@@ -203,9 +203,20 @@ func (p *Peer) setupDataChannelHandlers(dcReady chan struct{}) {
 	})
 
 	p.dc.OnMessage(func(msg webrtc.DataChannelMessage) {
-		logger.Verbosef("[Jazz] Received %d bytes on publisher DC", len(msg.Data))
-		if p.onData != nil && len(msg.Data) > 0 {
-			p.onData(msg.Data)
+		logger.Verbosef("[Jazz] Received %d bytes on publisher DC (raw)", len(msg.Data))
+
+		payload, ok := DecodeDataPacket(msg.Data)
+		if !ok {
+			logger.Debugf("[Jazz] Failed to decode DataPacket, trying raw")
+			if p.onData != nil && len(msg.Data) > 0 {
+				p.onData(msg.Data)
+			}
+			return
+		}
+
+		logger.Verbosef("[Jazz] Decoded DataPacket: %d bytes payload", len(payload))
+		if p.onData != nil && len(payload) > 0 {
+			p.onData(payload)
 		}
 	})
 
@@ -216,9 +227,20 @@ func (p *Peer) setupDataChannelHandlers(dcReady chan struct{}) {
 		}
 
 		dc.OnMessage(func(msg webrtc.DataChannelMessage) {
-			logger.Verbosef("[Jazz] Received %d bytes on subscriber DC (_reliable)", len(msg.Data))
-			if p.onData != nil && len(msg.Data) > 0 {
-				p.onData(msg.Data)
+			logger.Verbosef("[Jazz] Received %d bytes on subscriber DC (_reliable, raw)", len(msg.Data))
+
+			payload, ok := DecodeDataPacket(msg.Data)
+			if !ok {
+				logger.Debugf("[Jazz] Failed to decode DataPacket from subscriber, trying raw")
+				if p.onData != nil && len(msg.Data) > 0 {
+					p.onData(msg.Data)
+				}
+				return
+			}
+
+			logger.Verbosef("[Jazz] Decoded DataPacket from subscriber: %d bytes payload", len(payload))
+			if p.onData != nil && len(payload) > 0 {
+				p.onData(payload)
 			}
 		})
 	})
@@ -452,7 +474,10 @@ func (p *Peer) processSendQueue() {
 		case <-p.closeCh:
 			return
 		case data := <-p.sendQueue:
-			if err := p.dc.Send(data); err != nil {
+			encoded := EncodeDataPacket(data)
+			logger.Verbosef("[Jazz] Sending %d bytes (encoded to %d bytes)", len(data), len(encoded))
+
+			if err := p.dc.Send(encoded); err != nil {
 				logger.Debugf("send error: %v", err)
 				p.queueReconnect()
 				return