aiortc / aioquic

Line 437 in 5757081

return pull_opaque(buf, 1).decode("ascii")

decodes ALPN values as ASCII strings. This is usually OK, but not always. Grease for ALPN, as defined in RFC 8701, includes ALPN values that are not safe to decode as ASCII. aioquic as a server doesn't like those and will crash if a client sends ALPN like this. It probably shouldn't.

One fix is perhaps trivial: catch the decode error when adding to the list of extension values and just skip those. Real ALPN values are likely to be ASCII strings for now, so the only problem this might create is that people won't be able to configure aioquic with a non-ASCII protocol name.

Stack

handle: <Handle _SelectorDatagramTransport._read_ready()>
Traceback (most recent call last):
  File "/usr/lib64/python3.11/asyncio/events.py", line 80, in _run
    self._context.run(self._callback, *self._args)
  File "/usr/lib64/python3.11/asyncio/selector_events.py", line 1169, in _read_ready
    self._protocol.datagram_received(data, addr)
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/asyncio/server.py", line 149, in datagram_received
    protocol.datagram_received(data, addr)
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/asyncio/protocol.py", line 135, in datagram_received
    self._quic.receive_datagram(cast(bytes, data), addr, now=self._loop.time())
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/quic/connection.py", line 980, in receive_datagram
    is_ack_eliciting, is_probing = self._payload_received(
                                   ^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/quic/connection.py", line 2260, in _payload_received
    frame_handler(context, frame_type, buf)
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/quic/connection.py", line 1498, in _handle_crypto_frame
    self.tls.handle_message(event.data, self._crypto_buffers)
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/tls.py", line 1272, in handle_message
    self._server_handle_hello(
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/tls.py", line 1586, in _server_handle_hello
    peer_hello = pull_client_hello(input_buf)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/tls.py", line 557, in pull_client_hello
    pull_list(buf, 2, pull_extension)
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/tls.py", line 382, in pull_list
    items.append(func())
                 ^^^^^^
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/tls.py", line 541, in pull_extension
    hello.alpn_protocols = pull_list(
                           ^^^^^^^^^^
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/tls.py", line 382, in pull_list
    items.append(func())
                 ^^^^^^
  File "/home/jesup/src/mozilla/inbound_merge/obj-debug/_virtualenvs/wpt/lib/python3.11/site-packages/aioquic/tls.py", line 441, in pull_alpn_protocol
    return pull_opaque(buf, 1).decode("ascii")
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
UnicodeDecodeError: 'ascii' codec can't decode byte 0xba in position 0: ordinal not in range(128)

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

This is now fixed and will be in the next release.

Non-ASCII ALPN