Updated Yamux impl.,added tests for yamux and mplex

libp2p/stream_muxer/mplex/mplex_stream.py

@@ -46,8 +46,9 @@ class MplexStream(IMuxedStream):
     read_deadline: int | None
     write_deadline: int | None
 
-    # TODO: Add lock for read/write to avoid interleaving receiving messages?
     close_lock: trio.Lock
+    read_lock: trio.Lock
+    write_lock: trio.Lock
 
     # NOTE: `dataIn` is size of 8 in Go implementation.
     incoming_data_channel: "trio.MemoryReceiveChannel[bytes]"
@@ -80,6 +81,8 @@ class MplexStream(IMuxedStream):
         self.event_remote_closed = trio.Event()
         self.event_reset = trio.Event()
         self.close_lock = trio.Lock()
+        self.read_lock = trio.Lock()
+        self.write_lock = trio.Lock()
         self.incoming_data_channel = incoming_data_channel
         self._buf = bytearray()
 
@@ -113,48 +116,49 @@ class MplexStream(IMuxedStream):
         :param n: number of bytes to read
         :return: bytes actually read
         """
-        if n is not None and n < 0:
+        async with self.read_lock:
-            raise ValueError(
+            if n is not None and n < 0:
-                "the number of bytes to read `n` must be non-negative or "
+                raise ValueError(
-                f"`None` to indicate read until EOF, got n={n}"
+                    "the number of bytes to read `n` must be non-negative or "
-            )
+                    f"`None` to indicate read until EOF, got n={n}"
-        if self.event_reset.is_set():
+                )
-            raise MplexStreamReset
+            if self.event_reset.is_set():
-        if n is None:
+                raise MplexStreamReset
-            return await self._read_until_eof()
+            if n is None:
-        if len(self._buf) == 0:
+                return await self._read_until_eof()
-            data: bytes
+            if len(self._buf) == 0:
-            # Peek whether there is data available. If yes, we just read until there is
+                data: bytes
-            # no data, then return.
+                # Peek whether there is data available. If yes, we just read until
-            try:
+                # there is no data, then return.
-                data = self.incoming_data_channel.receive_nowait()
-                self._buf.extend(data)
-            except trio.EndOfChannel:
-                raise MplexStreamEOF
-            except trio.WouldBlock:
-                # We know `receive` will be blocked here. Wait for data here with
-                # `receive` and catch all kinds of errors here.
                 try:
-                    data = await self.incoming_data_channel.receive()
+                    data = self.incoming_data_channel.receive_nowait()
                     self._buf.extend(data)
                 except trio.EndOfChannel:
-                    if self.event_reset.is_set():
+                    raise MplexStreamEOF
-                        raise MplexStreamReset
+                except trio.WouldBlock:
-                    if self.event_remote_closed.is_set():
+                    # We know `receive` will be blocked here. Wait for data here with
-                        raise MplexStreamEOF
+                    # `receive` and catch all kinds of errors here.
-                except trio.ClosedResourceError as error:
+                    try:
-                    # Probably `incoming_data_channel` is closed in `reset` when we are
+                        data = await self.incoming_data_channel.receive()
-                    # waiting for `receive`.
+                        self._buf.extend(data)
-                    if self.event_reset.is_set():
+                    except trio.EndOfChannel:
-                        raise MplexStreamReset
+                        if self.event_reset.is_set():
-                    raise Exception(
+                            raise MplexStreamReset
-                        "`incoming_data_channel` is closed but stream is not reset. "
+                        if self.event_remote_closed.is_set():
-                        "This should never happen."
+                            raise MplexStreamEOF
-                    ) from error
+                    except trio.ClosedResourceError as error:
-        self._buf.extend(self._read_return_when_blocked())
+                        # Probably `incoming_data_channel` is closed in `reset` when
-        payload = self._buf[:n]
+                        # we are waiting for `receive`.
-        self._buf = self._buf[len(payload) :]
+                        if self.event_reset.is_set():
-        return bytes(payload)
+                            raise MplexStreamReset
+                        raise Exception(
+                            "`incoming_data_channel` is closed but stream is not reset."
+                            "This should never happen."
+                        ) from error
+            self._buf.extend(self._read_return_when_blocked())
+            payload = self._buf[:n]
+            self._buf = self._buf[len(payload) :]
+            return bytes(payload)
 
     async def write(self, data: bytes) -> None:
         """
@@ -162,14 +166,15 @@ class MplexStream(IMuxedStream):
 
         :return: number of bytes written
         """
-        if self.event_local_closed.is_set():
+        async with self.write_lock:
-            raise MplexStreamClosed(f"cannot write to closed stream: data={data!r}")
+            if self.event_local_closed.is_set():
-        flag = (
+                raise MplexStreamClosed(f"cannot write to closed stream: data={data!r}")
-            HeaderTags.MessageInitiator
+            flag = (
-            if self.is_initiator
+                HeaderTags.MessageInitiator
-            else HeaderTags.MessageReceiver
+                if self.is_initiator
-        )
+                else HeaderTags.MessageReceiver
-        await self.muxed_conn.send_message(flag, data, self.stream_id)
+            )
+            await self.muxed_conn.send_message(flag, data, self.stream_id)
 
     async def close(self) -> None:
         """

libp2p/stream_muxer/yamux/yamux.py

@@ -77,6 +77,8 @@ class YamuxStream(IMuxedStream):
         self.send_window = DEFAULT_WINDOW_SIZE
         self.recv_window = DEFAULT_WINDOW_SIZE
         self.window_lock = trio.Lock()
+        self.read_lock = trio.Lock()
+        self.write_lock = trio.Lock()
 
     async def __aenter__(self) -> "YamuxStream":
         """Enter the async context manager."""
@@ -98,16 +100,32 @@ class YamuxStream(IMuxedStream):
         # Flow control: Check if we have enough send window
         total_len = len(data)
         sent = 0
-
+        logging.debug(f"Stream {self.stream_id}: Starts writing {total_len} bytes ")
         while sent < total_len:
+            # Wait for available window with timeout
+            timeout = False
             async with self.window_lock:
-                # Wait for available window
+                if self.send_window == 0:
-                while self.send_window == 0 and not self.closed:
+                    logging.debug(
-                    # Release lock while waiting
+                        f"Stream {self.stream_id}: Window is zero, waiting for update"
+                    )
+                    # Release lock and wait with timeout
                     self.window_lock.release()
-                    await trio.sleep(0.01)
+                    # To avoid re-acquiring the lock immediately,
+                    with trio.move_on_after(5.0) as cancel_scope:
+                        while self.send_window == 0 and not self.closed:
+                            await trio.sleep(0.01)
+                        # If we timed out, cancel the scope
+                        timeout = cancel_scope.cancelled_caught
+                    # Re-acquire lock
                     await self.window_lock.acquire()
 
+                # If we timed out waiting for window update, raise an error
+                if timeout:
+                    raise MuxedStreamError(
+                        "Timed out waiting for window update after 5 seconds."
+                    )
+
                 if self.closed:
                     raise MuxedStreamError("Stream is closed")
 
@@ -123,25 +141,53 @@ class YamuxStream(IMuxedStream):
                 await self.conn.secured_conn.write(header + chunk)
                 sent += to_send
 
-        # If window is getting low, consider updating
+    async def send_window_update(
-        if self.send_window < DEFAULT_WINDOW_SIZE // 2:
+        self, increment: int | None, skip_lock: bool = False
-            await self.send_window_update()
+    ) -> None:
+        """
+        Send a window update to peer.
 
-    async def send_window_update(self, increment: int | None = None) -> None:
+        param:increment: The amount to increment the window size by.
-        """Send a window update to peer."""
+        If None, uses the difference between DEFAULT_WINDOW_SIZE
+        and current receive window.
+        param:skip_lock (bool): If True, skips acquiring window_lock.
+        This should only be used when calling from a context
+        that already holds the lock.
+        """
+        increment_value = 0
         if increment is None:
-            increment = DEFAULT_WINDOW_SIZE - self.recv_window
+            increment_value = DEFAULT_WINDOW_SIZE - self.recv_window
-
+        else:
-        if increment <= 0:
+            increment_value = increment
+        if increment_value <= 0:
+            # If increment is zero or negative, skip sending update
+            logging.debug(
+                f"Stream {self.stream_id}: Skipping window update"
+                f"(increment={increment})"
+            )
             return
+        logging.debug(
+            f"Stream {self.stream_id}: Sending window update with increment={increment}"
+        )
 
-        async with self.window_lock:
+        async def _do_window_update() -> None:
-            self.recv_window += increment
+            self.recv_window += increment_value
             header = struct.pack(
-                YAMUX_HEADER_FORMAT, 0, TYPE_WINDOW_UPDATE, 0, self.stream_id, increment
+                YAMUX_HEADER_FORMAT,
+                0,
+                TYPE_WINDOW_UPDATE,
+                0,
+                self.stream_id,
+                increment_value,
             )
             await self.conn.secured_conn.write(header)
 
+        if skip_lock:
+            await _do_window_update()
+        else:
+            async with self.window_lock:
+                await _do_window_update()
+
     async def read(self, n: int | None = -1) -> bytes:
         # Handle None value for n by converting it to -1
         if n is None:
@@ -198,11 +244,19 @@ class YamuxStream(IMuxedStream):
                 # Return all buffered data
                 data = bytes(buffer)
                 buffer.clear()
-                logging.debug(f"Stream {self.stream_id}: Returning {len(data)} bytes")
                 return data
 
-        # For specific size read (n > 0), return available data immediately
+        data = await self.conn.read_stream(self.stream_id, n)
-        return await self.conn.read_stream(self.stream_id, n)
+        async with self.window_lock:
+            self.recv_window -= len(data)
+            # Automatically send a window update if recv_window is low
+            if self.recv_window <= DEFAULT_WINDOW_SIZE // 2:
+                logging.debug(
+                    f"Stream {self.stream_id}: "
+                    f"Low recv_window ({self.recv_window}), sending update"
+                )
+                await self.send_window_update(None, skip_lock=True)
+        return data
 
     async def close(self) -> None:
         if not self.send_closed:

newsfragments/639.feature.rst

@@ -0,0 +1 @@
+Added separate read and write locks to the `MplexStream` & `YamuxStream` class.This ensures thread-safe access and data integrity when multiple coroutines interact with the same MplexStream instance.

tests/core/stream_muxer/test_mplex_read_write_lock.py

@@ -0,0 +1,124 @@
+import pytest
+import trio
+
+from libp2p.abc import ISecureConn
+from libp2p.crypto.keys import PrivateKey, PublicKey
+from libp2p.peer.id import ID
+from libp2p.stream_muxer.mplex.constants import (
+    HeaderTags,
+)
+from libp2p.stream_muxer.mplex.datastructures import (
+    StreamID,
+)
+from libp2p.stream_muxer.mplex.mplex import (
+    Mplex,
+)
+from libp2p.stream_muxer.mplex.mplex_stream import (
+    MplexStream,
+)
+
+
+class DummySecureConn(ISecureConn):
+    """A minimal implementation of ISecureConn for testing."""
+
+    async def write(self, data: bytes) -> None:
+        pass
+
+    async def read(self, n: int | None = -1) -> bytes:
+        return b""
+
+    async def close(self) -> None:
+        pass
+
+    def get_remote_address(self) -> tuple[str, int] | None:
+        return None
+
+    def get_local_peer(self) -> ID:
+        return ID(b"local")
+
+    def get_local_private_key(self) -> PrivateKey:
+        return PrivateKey()  # Dummy key for testing
+
+    def get_remote_peer(self) -> ID:
+        return ID(b"remote")
+
+    def get_remote_public_key(self) -> PublicKey:
+        return PublicKey()  # Dummy key for testing
+
+
+class DummyMuxedConn(Mplex):
+    """A minimal mock of Mplex for testing read/write locks."""
+
+    def __init__(self) -> None:
+        self.secured_conn = DummySecureConn()
+        self.peer_id = ID(b"dummy")
+        self.streams = {}
+        self.streams_lock = trio.Lock()
+        self.event_shutting_down = trio.Event()
+        self.event_closed = trio.Event()
+        self.event_started = trio.Event()
+        self.stream_backlog_limit = 256
+        self.stream_backlog_semaphore = trio.Semaphore(256)
+        channels = trio.open_memory_channel[MplexStream](0)
+        self.new_stream_send_channel, self.new_stream_receive_channel = channels
+
+    async def send_message(
+        self, flag: HeaderTags, data: bytes, stream_id: StreamID
+    ) -> None:
+        await trio.sleep(0.01)
+
+
+@pytest.mark.trio
+async def test_concurrent_writes_are_serialized():
+    stream_id = StreamID(1, True)
+    send_log = []
+
+    class LoggingMuxedConn(DummyMuxedConn):
+        async def send_message(
+            self, flag: HeaderTags, data: bytes, stream_id: StreamID
+        ) -> None:
+            send_log.append(data)
+            await trio.sleep(0.01)
+
+    memory_send, memory_recv = trio.open_memory_channel(8)
+    stream = MplexStream(
+        name="test",
+        stream_id=stream_id,
+        muxed_conn=LoggingMuxedConn(),
+        incoming_data_channel=memory_recv,
+    )
+
+    async def writer(data):
+        await stream.write(data)
+
+    async with trio.open_nursery() as nursery:
+        for i in range(5):
+            nursery.start_soon(writer, f"msg-{i}".encode())
+    # Order doesn't matter due to concurrent execution
+    assert sorted(send_log) == sorted([f"msg-{i}".encode() for i in range(5)])
+
+
+@pytest.mark.trio
+async def test_concurrent_reads_are_serialized():
+    stream_id = StreamID(2, True)
+    muxed_conn = DummyMuxedConn()
+    memory_send, memory_recv = trio.open_memory_channel(8)
+    results = []
+    stream = MplexStream(
+        name="test",
+        stream_id=stream_id,
+        muxed_conn=muxed_conn,
+        incoming_data_channel=memory_recv,
+    )
+    for i in range(5):
+        await memory_send.send(f"data-{i}".encode())
+    await memory_send.aclose()
+
+    async def reader():
+        data = await stream.read(6)
+        results.append(data)
+
+    async with trio.open_nursery() as nursery:
+        for _ in range(5):
+            nursery.start_soon(reader)
+    assert sorted(results) == [f"data-{i}".encode() for i in range(5)]

tests/core/stream_muxer/test_yamux_read_write_lock.py

@@ -0,0 +1,207 @@
+import logging
+
+import pytest
+import trio
+from trio.testing import (
+    memory_stream_pair,
+)
+
+from libp2p.abc import IRawConnection
+from libp2p.crypto.ed25519 import (
+    create_new_key_pair,
+)
+from libp2p.peer.id import (
+    ID,
+)
+from libp2p.security.insecure.transport import (
+    InsecureTransport,
+)
+from libp2p.stream_muxer.yamux.yamux import (
+    Yamux,
+    YamuxStream,
+)
+
+
+class TrioStreamAdapter(IRawConnection):
+    """Adapter to make trio memory streams work with libp2p."""
+
+    def __init__(self, send_stream, receive_stream, is_initiator=False):
+        self.send_stream = send_stream
+        self.receive_stream = receive_stream
+        self.is_initiator = is_initiator
+
+    async def write(self, data: bytes) -> None:
+        logging.debug(f"Attempting to write {len(data)} bytes")
+        with trio.move_on_after(2):
+            await self.send_stream.send_all(data)
+
+    async def read(self, n: int | None = None) -> bytes:
+        if n is None or n <= 0:
+            raise ValueError("Reading unbounded or zero bytes not supported")
+        logging.debug(f"Attempting to read {n} bytes")
+        with trio.move_on_after(2):
+            data = await self.receive_stream.receive_some(n)
+            logging.debug(f"Read {len(data)} bytes")
+            return data
+
+    async def close(self) -> None:
+        logging.debug("Closing stream")
+        await self.send_stream.aclose()
+        await self.receive_stream.aclose()
+
+    def get_remote_address(self) -> tuple[str, int] | None:
+        """Return None since this is a test adapter without real network info."""
+        return None
+
+
+@pytest.fixture
+def key_pair():
+    return create_new_key_pair()
+
+
+@pytest.fixture
+def peer_id(key_pair):
+    return ID.from_pubkey(key_pair.public_key)
+
+
+@pytest.fixture
+async def secure_conn_pair(key_pair, peer_id):
+    """Create a pair of secure connections for testing."""
+    logging.debug("Setting up secure_conn_pair")
+    client_send, server_receive = memory_stream_pair()
+    server_send, client_receive = memory_stream_pair()
+
+    client_rw = TrioStreamAdapter(client_send, client_receive)
+    server_rw = TrioStreamAdapter(server_send, server_receive)
+
+    insecure_transport = InsecureTransport(key_pair)
+
+    async def run_outbound(nursery_results):
+        with trio.move_on_after(5):
+            client_conn = await insecure_transport.secure_outbound(client_rw, peer_id)
+            logging.debug("Outbound handshake complete")
+            nursery_results["client"] = client_conn
+
+    async def run_inbound(nursery_results):
+        with trio.move_on_after(5):
+            server_conn = await insecure_transport.secure_inbound(server_rw)
+            logging.debug("Inbound handshake complete")
+            nursery_results["server"] = server_conn
+
+    nursery_results = {}
+    async with trio.open_nursery() as nursery:
+        nursery.start_soon(run_outbound, nursery_results)
+        nursery.start_soon(run_inbound, nursery_results)
+        await trio.sleep(0.1)  # Give tasks a chance to finish
+
+    client_conn = nursery_results.get("client")
+    server_conn = nursery_results.get("server")
+
+    if client_conn is None or server_conn is None:
+        raise RuntimeError("Handshake failed: client_conn or server_conn is None")
+
+    logging.debug("secure_conn_pair setup complete")
+    return client_conn, server_conn
+
+
+@pytest.fixture
+async def yamux_pair(secure_conn_pair, peer_id):
+    """Create a pair of Yamux multiplexers for testing."""
+    logging.debug("Setting up yamux_pair")
+    client_conn, server_conn = secure_conn_pair
+    client_yamux = Yamux(client_conn, peer_id, is_initiator=True)
+    server_yamux = Yamux(server_conn, peer_id, is_initiator=False)
+    async with trio.open_nursery() as nursery:
+        with trio.move_on_after(5):
+            nursery.start_soon(client_yamux.start)
+            nursery.start_soon(server_yamux.start)
+            await trio.sleep(0.1)
+            logging.debug("yamux_pair started")
+        yield client_yamux, server_yamux
+    logging.debug("yamux_pair cleanup")
+
+
+@pytest.mark.trio
+async def test_yamux_race_condition_without_locks(yamux_pair):
+    """
+    Test for race-around/interleaving in Yamux streams when read/write
+    locks are disabled.
+    This launches concurrent writers/readers on both sides of a stream.
+    If there is no proper locking, the received data may be interleaved
+    or corrupted.
+
+    The test creates structured messages and verifies they are received
+    intact and in order.
+    Without proper locking, concurrent read/write operations could cause
+    data corruption
+    or message interleaving, which this test will catch.
+    """
+    client_yamux, server_yamux = yamux_pair
+    client_stream: YamuxStream = await client_yamux.open_stream()
+    server_stream: YamuxStream = await server_yamux.accept_stream()
+    MSG_COUNT = 10
+    MSG_SIZE = 256 * 1024
+    client_msgs = [
+        f"CLIENT-MSG-{i:03d}-".encode().ljust(MSG_SIZE, b"C") for i in range(MSG_COUNT)
+    ]
+    server_msgs = [
+        f"SERVER-MSG-{i:03d}-".encode().ljust(MSG_SIZE, b"S") for i in range(MSG_COUNT)
+    ]
+    client_received = []
+    server_received = []
+
+    async def writer(stream, msgs, name):
+        """Write messages with minimal delays to encourage race conditions."""
+        for i, msg in enumerate(msgs):
+            await stream.write(msg)
+            # Yield control frequently to encourage interleaving
+            if i % 5 == 0:
+                await trio.sleep(0.005)
+
+    async def reader(stream, received, name):
+        """Read messages and store them for verification."""
+        for i in range(MSG_COUNT):
+            data = await stream.read(MSG_SIZE)
+            received.append(data)
+            if i % 3 == 0:
+                await trio.sleep(0.001)
+
+    # Running all operations concurrently
+    async with trio.open_nursery() as nursery:
+        nursery.start_soon(writer, client_stream, client_msgs, "client")
+        nursery.start_soon(writer, server_stream, server_msgs, "server")
+        nursery.start_soon(reader, client_stream, client_received, "client")
+        nursery.start_soon(reader, server_stream, server_received, "server")
+
+    assert len(client_received) == MSG_COUNT, (
+        f"Client received {len(client_received)} messages, expected {MSG_COUNT}"
+    )
+    assert len(server_received) == MSG_COUNT, (
+        f"Server received {len(server_received)} messages, expected {MSG_COUNT}"
+    )
+    assert client_received == server_msgs, (
+        "Client did not receive server messages in order or intact!"
+    )
+    assert server_received == client_msgs, (
+        "Server did not receive client messages in order or intact!"
+    )
+    for i, msg in enumerate(client_received):
+        # logging.debug(f"datatype of msg: {type(msg)}, length: {len(msg)}")
+        # logging.debug(f"datatype of msg: {type(b"SERVER-MSG-")}")
+        assert len(msg) == MSG_SIZE, (
+            f"Client message {i} has wrong size: {len(msg)} != {MSG_SIZE}"
+        )
+        assert msg.startswith(b"SERVER-MSG-"), (
+            f"Client message {i} doesn't start with expected prefix"
+        )
+
+    for i, msg in enumerate(server_received):
+        assert len(msg) == MSG_SIZE, (
+            f"Server message {i} has wrong size: {len(msg)} != {MSG_SIZE}"
+        )
+        assert msg.startswith(b"CLIENT-MSG-"), (
+            f"Server message {i} doesn't start with expected prefix"
+        )
+
+    await client_stream.close()
+    await server_stream.close()