refactor(webrtc): deduplicate _varint.py — use libp2p.utils.varint

libp2p/transport/webrtc/signaling.py

@@ -32,8 +32,8 @@
 import trio
 
 from libp2p.abc import INetStream
+from libp2p.utils.varint import decode_uvarint_from_stream, encode_uvarint
 
-from ._varint import encode_uvarint
 from .exceptions import WebRTCSignalingError
 from .signaling_pb.signaling_pb2 import SignalingMessage
 
@@ -74,7 +74,7 @@ async def read_signaling_message(stream: INetStream) -> SignalingMessage:
     :raises WebRTCSignalingError: If reading or parsing fails.
     """
     try:
-        length = await _read_uvarint(stream)
+        length = await decode_uvarint_from_stream(stream)
         if length > _MAX_SIGNALING_MSG_SIZE:
             raise WebRTCSignalingError(
                 f"Signaling message too large: {length} bytes "
@@ -261,24 +261,3 @@ async def _receive_expected(self, expected_type: int) -> SignalingMessage:
                 f"Expected signaling message type {expected_type}, got {msg.type}"
             )
         return msg
-
-
-# ------------------------------------------------------------------
-# Streaming varint read (sync encoder/decoder live in ._varint)
-# ------------------------------------------------------------------
-
-
-async def _read_uvarint(stream: INetStream) -> int:
-    """Read an unsigned varint from a libp2p :class:`INetStream`."""
-    result = 0
-    shift = 0
-    for _ in range(10):  # Max 10 bytes for uint64 varint
-        byte_data = await stream.read(1)
-        if not byte_data:
-            raise WebRTCSignalingError("Stream closed while reading varint")
-        byte = byte_data[0]
-        result |= (byte & 0x7F) << shift
-        if not (byte & 0x80):
-            return result
-        shift += 7
-    raise WebRTCSignalingError("Varint too long (> 10 bytes)")

libp2p/transport/webrtc/stream.py

@@ -19,8 +19,8 @@
 import trio
 
 from libp2p.abc import IMuxedStream
+from libp2p.utils.varint import decode_varint_with_size, encode_uvarint
 
-from ._varint import decode_uvarint, encode_uvarint
 from .constants import MAX_MESSAGE_SIZE, MAX_PAYLOAD_SIZE
 from .exceptions import WebRTCStreamError
 from .pb.webrtc_pb2 import Message
@@ -301,7 +301,7 @@ def on_data(self, raw: bytes) -> None:
         the mutations inline.
         """
         try:
-            length, consumed = decode_uvarint(raw)
+            length, consumed = decode_varint_with_size(raw)
         except ValueError as e:
             logger.warning(
                 "WebRTCStream channel=%d: malformed varint prefix: %s",

newsfragments/1355.internal.rst

@@ -0,0 +1 @@
+Removed ``libp2p/transport/webrtc/_varint.py`` and migrated WebRTC stream and signaling framing to use the shared ``libp2p.utils.varint`` utilities (``encode_uvarint``, ``decode_varint_with_size``, ``decode_uvarint_from_stream``), eliminating a duplicate in-tree varint implementation.

tests/core/transport/webrtc/test_connection.py

@@ -124,8 +124,8 @@ class TestMessageRouting:
     async def test_on_channel_message_routes_to_stream(self):
         conn = _make_connection()
         stream = await conn.open_stream()
-        from libp2p.transport.webrtc._varint import encode_uvarint
         from libp2p.transport.webrtc.pb.webrtc_pb2 import Message
+        from libp2p.utils.varint import encode_uvarint
 
         proto = Message(message=b"test-data").SerializeToString()
         framed = encode_uvarint(len(proto)) + proto

tests/core/transport/webrtc/test_signaling.py

@@ -13,14 +13,16 @@
 import pytest
 import trio
 
-from libp2p.transport.webrtc._varint import encode_uvarint as _encode_uvarint
 from libp2p.transport.webrtc.signaling import (
     SignalingSession,
-    _read_uvarint,
     read_signaling_message,
     write_signaling_message,
 )
 from libp2p.transport.webrtc.signaling_pb.signaling_pb2 import SignalingMessage
+from libp2p.utils.varint import (
+    decode_uvarint_from_stream as _read_uvarint,
+    encode_uvarint as _encode_uvarint,
+)
 
 
 class MockStream:

tests/core/transport/webrtc/test_stream.py

@@ -9,10 +9,10 @@
 
 import pytest
 
-from libp2p.transport.webrtc._varint import decode_uvarint, encode_uvarint
 from libp2p.transport.webrtc.constants import MAX_PAYLOAD_SIZE
 from libp2p.transport.webrtc.pb.webrtc_pb2 import Message
 from libp2p.transport.webrtc.stream import StreamState, WebRTCStream
+from libp2p.utils.varint import decode_varint_with_size, encode_uvarint
 
 
 def _framed(msg: Message) -> bytes:
@@ -23,7 +23,7 @@ def _framed(msg: Message) -> bytes:
 
 def _parse_framed(raw: bytes) -> Message:
     """Inverse of :func:`_framed` — decode the wire format back to a Message."""
-    length, consumed = decode_uvarint(raw)
+    length, consumed = decode_varint_with_size(raw)
     msg = Message()
     msg.ParseFromString(raw[consumed : consumed + length])
     return msg