🐛 fix handling aggressive ACKs watcher in some QUIC server implementa…

…tion leading to a ProtocolError (#161)

CHANGES.rst

@@ -1,3 +1,9 @@
+2.10.906 (2024-10-17)
+=====================
+
+- Fixed handling aggressive ACKs watcher in some QUIC server implementation leading to a ``ProtocolError``.
+  We're actively working toward a solution that will avoid to recycle the QUIC connection.
+
 2.10.905 (2024-10-15)
 =====================
 

src/urllib3/_version.py

@@ -1,4 +1,4 @@
 # This file is protected via CODEOWNERS
 from __future__ import annotations
 
-__version__ = "2.10.905"
+__version__ = "2.10.906"

src/urllib3/backend/_async/hface.py

@@ -43,6 +43,7 @@
     IncompleteRead,
     InvalidHeader,
     MustDowngradeError,
+    MustRedialError,
     ProtocolError,
     ResponseNotReady,
     SSLError,
@@ -793,6 +794,20 @@ async def __exchange_until(
                 stream_related_event: bool = hasattr(event, "stream_id")
 
                 if not stream_related_event and isinstance(event, ConnectionTerminated):
+                    # some server implementation may be aggressive toward "idle" session
+                    # this is especially true when using QUIC.
+                    # For example, google/quiche expect regular ACKs, otherwise will
+                    # deduct that network conn is dead.
+                    # todo: we will need some kind of background watch constrained by TrafficPolice
+                    # see: https://github.com/google/quiche/commit/c4bb0723f0a03e135bc9328b59a39382761f3de6
+                    #      https://github.com/google/quiche/blob/92b45f743288ea2f43ae8cdc4a783ef252e41d93/quiche/quic/core/quic_connection.cc#L6322
+                    if event.error_code == 0:
+                        self._protocol = None
+                        await self.close()
+                        raise MustRedialError(
+                            f"Remote peer just closed our connection, probably for not answering to unsolicited packet. ({event.message})"
+                        )
+
                     if (
                         event.error_code == 400
                         and event.message

src/urllib3/backend/hface.py

@@ -47,6 +47,7 @@
     IncompleteRead,
     InvalidHeader,
     MustDowngradeError,
+    MustRedialError,
     ProtocolError,
     ResponseNotReady,
     SSLError,
@@ -844,6 +845,20 @@ def __exchange_until(
                 stream_related_event: bool = hasattr(event, "stream_id")
 
                 if not stream_related_event and isinstance(event, ConnectionTerminated):
+                    # some server implementation may be aggressive toward "idle" session
+                    # this is especially true when using QUIC.
+                    # For example, google/quiche expect regular ACKs, otherwise will
+                    # deduct that network conn is dead.
+                    # todo: we will need some kind of background watch constrained by TrafficPolice
+                    # see: https://github.com/google/quiche/commit/c4bb0723f0a03e135bc9328b59a39382761f3de6
+                    #      https://github.com/google/quiche/blob/92b45f743288ea2f43ae8cdc4a783ef252e41d93/quiche/quic/core/quic_connection.cc#L6322
+                    if event.error_code == 0:
+                        self._protocol = None
+                        self.close()
+                        raise MustRedialError(
+                            f"Remote peer just closed our connection, probably for not answering to unsolicited packet. ({event.message})"
+                        )
+
                     if (
                         event.error_code == 400
                         and event.message

src/urllib3/exceptions.py

@@ -351,3 +351,7 @@ class RecoverableError(HTTPError):
 
 class MustDowngradeError(RecoverableError):
     """An error occurred with a protocol and can be circumvented using an older protocol."""
+
+
+class MustRedialError(RecoverableError):
+    """The remote peer closed the connection without error, but expected it to be still open."""