fix: accept new streams for both DATA and WINDOW_UPDATE frames with the SYN flag (#702)

acul71 · seetadev · web-flow · commit ef16f3c99310 · 2025-06-29T10:50:17.000+02:00
* fix: accept new streams for both  and  frames with the  flag

* doc: newsfragment

---------

Co-authored-by: Manu Sheel Gupta &lt;manusheel.edu@gmail.com&gt;
diff --git a/libp2p/stream_muxer/yamux/yamux.py b/libp2p/stream_muxer/yamux/yamux.py
@@ -493,7 +493,7 @@ async def handle_incoming(self) -> None:
                     f"type={typ}, flags={flags}, stream_id={stream_id},"
                     f"length={length}"
                 )
-                if typ == TYPE_DATA and flags & FLAG_SYN:
+                if (typ == TYPE_DATA or typ == TYPE_WINDOW_UPDATE) and flags & FLAG_SYN:
                     async with self.streams_lock:
                         if stream_id not in self.streams:
                             stream = YamuxStream(stream_id, self, False)
diff --git a/newsfragments/701.bugfix.rst b/newsfragments/701.bugfix.rst
@@ -0,0 +1 @@
+align stream creation logic with yamux specification

Original file line number	Diff line number	Diff line change
`@@ -493,7 +493,7 @@ async def handle_incoming(self) -> None:`
`493`	`493`	`f"type={typ}, flags={flags}, stream_id={stream_id},"`
`494`	`494`	`f"length={length}"`
`495`	`495`	`)`
`496`		`- if typ == TYPE_DATA and flags & FLAG_SYN:`
	`496`	`+ if (typ == TYPE_DATA or typ == TYPE_WINDOW_UPDATE) and flags & FLAG_SYN:`
`497`	`497`	`async with self.streams_lock:`
`498`	`498`	`if stream_id not in self.streams:`
`499`	`499`	`stream = YamuxStream(stream_id, self, False)`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+align stream creation logic with yamux specification`