Reject invalid control frames when building

[dajiaohuang]

Fixes #304.

Reject fragmented or oversized outgoing Close, Ping and Pong frames. Incoming-invalid-frame tests now construct malformed peer bytes directly, so they continue testing the parser without relying on the sender to generate protocol violations. Add output-boundary regressions for fragmentation, 126-byte rejection and valid empty/125-byte masked and unmasked controls.

Validation: the two rejection regressions fail against unchanged upstream framing and pass with this fix; all 62 frame/stream tests pass on Windows Python 3.13. The full local suite has 128 passes and one unrelated Unix-socket test failure because this Windows interpreter has no AF_UNIX. The supported Ubuntu/Python CI matrix must be checked on the updated head.

Additional validation: the complete suite passes on Linux/Python 3.12 (129 passed). The current-head upstream Actions run requires maintainer approval: https://github.com/Lawouach/WebSocket-for-Python/actions/runs/37199966249.

[auvipy]

lets see if the CI turn green

[auvipy]

test/test_websocket.py .................. [100%]

=================================== FAILURES ===================================
_________ WSFrameParserTest.test_fragmented_control_frame_is_too_large _________

self = <test.test_frame.WSFrameParserTest testMethod=test_fragmented_control_frame_is_too_large>

  def test_fragmented_control_frame_is_too_large(self):

  bytes = Frame(opcode=OPCODE_PING, body=b'*'*65536, fin=1).build()

              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

test/test_frame.py:202:

---

self = <ws4py.framing.Frame object at 0x7fc1acf349e0>

  def build(self):
      """
      Builds a frame from the instance's attributes and returns
      its bytes representation.
      """
      header = b''
  
      if self.fin > 0x1:
          raise ValueError('FIN bit parameter must be 0 or 1')
  
      if 0x3 <= self.opcode <= 0x7 or 0xB <= self.opcode:
          raise ValueError('Opcode cannot be a reserved opcode')
  
      if self.opcode in (OPCODE_CLOSE, OPCODE_PING, OPCODE_PONG):
          if self.fin != 1:
              raise ValueError('Control frames cannot be fragmented')
          if self.payload_length > 125:

          raise FrameTooLargeException()

E ws4py.exc.FrameTooLargeException

ws4py/framing.py:82: FrameTooLargeException
__________________ WSStreamTest.test_too_large_close_message ___________________

self = <test.test_stream.WSStreamTest testMethod=test_too_large_close_message>

  def test_too_large_close_message(self):
      payload = struct.pack("!H", 1000) + b'*' * 330
      f = Frame(opcode=OPCODE_CLOSE, body=payload,

            fin=1, masking_key=os.urandom(4)).build()

                                                  ^^^^^^^

test/test_stream.py:132:

---

self = <ws4py.framing.Frame object at 0x7fc1a3daa0c0>

  def build(self):
      """
      Builds a frame from the instance's attributes and returns
      its bytes representation.
      """
      header = b''
  
      if self.fin > 0x1:
          raise ValueError('FIN bit parameter must be 0 or 1')
  
      if 0x3 <= self.opcode <= 0x7 or 0xB <= self.opcode:
          raise ValueError('Opcode cannot be a reserved opcode')
  
      if self.opcode in (OPCODE_CLOSE, OPCODE_PING, OPCODE_PONG):
          if self.fin != 1:
              raise ValueError('Control frames cannot be fragmented')
          if self.payload_length > 125:

          raise FrameTooLargeException()

E ws4py.exc.FrameTooLargeException

ws4py/framing.py:82: FrameTooLargeException
=========================== short test summary info ============================
FAILED test/test_frame.py::WSFrameParserTest::test_fragmented_control_frame_is_too_large
FAILED test/test_stream.py::WSStreamTest::test_too_large_close_message - ws4p...
======================== 2 failed, 124 passed in 4.41s =========================
py312: exit 1 (4.63 seconds) /home/runner/work/WebSocket-for-Python/WebSocket-for-Python> pytest pid=2132
py312: FAIL code 1 (12.57=setup[7.94]+cmd[4.63] seconds)
evaluation failed :( (12.58 seconds)

[dajiaohuang]

The two failing fixtures now build malformed peer bytes directly, preserving their parser/stream checks without asking the validating sender to emit invalid controls. Added sender regressions for fragmentation, the 125/126-byte boundary, and masked/unmasked controls. The rejection cases fail against unchanged upstream framing; all 62 frame/stream tests pass with the fix. Full Windows validation has one separate AF_UNIX availability failure, recorded in the PR description; the updated Ubuntu matrix remains the acceptance check.