Switch to aiohttp masking method

This utilises the masking method used in aiohttp as it has better
performance, in addition the aiohttp test is also used. With thanks to
@willmcgugan for the original implementation.

This also removes the option of using wsaccel, it was previously
usable as an undocumented optional extra. This is considered
acceptable as the aiohttp masking method has similar performance to
wsaccel.

Author: pgjones

.travis.yml

@@ -24,21 +24,21 @@ matrix:
       dist: xenial
       sudo: true # required workaround for https://github.com/travis-ci/travis-ci/issues/9815
     - python: 3.6
-      env: TOXENV=py36 EXTRA_DEPS=wsaccel
+      env: TOXENV=py36
     - python: 3.7
-      env: TOXENV=py37 EXTRA_DEPS=wsaccel
+      env: TOXENV=py37
       dist: xenial
       sudo: true # required workaround for https://github.com/travis-ci/travis-ci/issues/9815
     - python: 3.6
-      env: TOXENV=autobahn EXTRA_DEPS=wsaccel SIDE=client
+      env: TOXENV=autobahn SIDE=client
     - python: 3.7
-      env: TOXENV=autobahn EXTRA_DEPS=wsaccel SIDE=client
+      env: TOXENV=autobahn SIDE=client
       dist: xenial
       sudo: true # required workaround for https://github.com/travis-ci/travis-ci/issues/9815
     - python: 3.6
-      env: TOXENV=autobahn EXTRA_DEPS=wsaccel SIDE=server
+      env: TOXENV=autobahn SIDE=server
     - python: 3.7
-      env: TOXENV=autobahn EXTRA_DEPS=wsaccel SIDE=server
+      env: TOXENV=autobahn SIDE=server
       dist: xenial
       sudo: true # required workaround for https://github.com/travis-ci/travis-ci/issues/9815
 

README.rst

@@ -92,9 +92,6 @@ Testing
 It passes the autobahn test suite completely and strictly in both client and
 server modes and using permessage-deflate.
 
-If `wsaccel <https://pypi.python.org/pypi/wsaccel>`_ is installed
-(optional), then it will be used to speed things up.
-
 If you want to run the compliance tests, go into the compliance directory and
 then to test client mode, in one shell run the Autobahn test server:
 

test/test_frame_protocol.py

@@ -1192,3 +1192,10 @@ def test_data_we_have_no_idea_what_to_do_with(self) -> None:
         with pytest.raises(ValueError):
             # Intentionally passing illegal type.
             proto.send_data(payload)  # type: ignore
+
+
+def test_xor_mask_simple() -> None:
+    masker = fp.XorMaskerSimple(b"1234")
+    assert masker.process(b"some very long data for masking by websocket") == (
+        b"B]^Q\x11DVFH\x12_[_U\x13PPFR\x14W]A\x14\\S@_X\\T\x14SK\x13CTP@[RYV@"
+    )

wsproto/frame_protocol.py

@@ -6,7 +6,6 @@
 WebSocket frame protocol implementation.
 """
 
-import itertools
 import os
 import struct
 from codecs import getincrementaldecoder, IncrementalDecoder
@@ -16,17 +15,33 @@
 if TYPE_CHECKING:
     from .extensions import Extension  # noqa
 
-try:
-    from wsaccel.xormask import XorMaskerSimple  # type: ignore
-except ImportError:
 
-    class XorMaskerSimple:  # type: ignore
-        def __init__(self, masking_key: bytes) -> None:
-            self._maskbytes = itertools.cycle(bytearray(masking_key))
+_XOR_TABLE = [bytes(a ^ b for a in range(256)) for b in range(256)]
 
-        def process(self, data: bytes) -> bytes:
-            maskbytes = self._maskbytes
-            return bytearray(b ^ next(maskbytes) for b in bytearray(data))
+
+class XorMaskerSimple:
+    def __init__(self, masking_key: bytes) -> None:
+        self._masking_key = masking_key
+
+    def process(self, data: bytes) -> bytes:
+        if data:  # pylint:disable=no-else-return
+            data_array = bytearray(data)
+            a, b, c, d = (_XOR_TABLE[n] for n in self._masking_key)
+            data_array[::4] = data_array[::4].translate(a)
+            data_array[1::4] = data_array[1::4].translate(b)
+            data_array[2::4] = data_array[2::4].translate(c)
+            data_array[3::4] = data_array[3::4].translate(d)
+
+            # Rotate the maksing key so that the next usage continues
+            # with the next key element, rather than restarting.
+            key_rotation = len(data) % 4
+            self._masking_key = (
+                self._masking_key[key_rotation:] + self._masking_key[:key_rotation]
+            )
+
+            return bytes(data_array)
+        else:
+            return data
 
 
 class XorMaskerNull: