Source code for autobahn.websocket.xormasker

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#
# The MIT License (MIT)
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# Copyright (c) typedef int GmbH
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# XorMaskerNull: pass-through implementation (no masking applied)
# Shared by all implementations (NVX, pure Python)


class XorMaskerNull(object):


    __slots__ = ("_ptr",)


    # noinspection PyUnusedLocal
    def __init__(self, mask=None):


        self._ptr = 0




    def pointer(self):
        return self._ptr




    def reset(self):
        self._ptr = 0




    def process(self, data):
        self._ptr += len(data)
        return data




# Import USES_NVX flag from parent module
from autobahn.websocket import USES_NVX

if USES_NVX:
    # Use NVX native implementation (CFFI-based, works on CPython and PyPy)
    from autobahn.nvx._xormasker import create_xor_masker
else:
    # Use pure Python fallback implementation

    # http://stackoverflow.com/questions/15014310/python3-xrange-lack-hurts
    try:
        # noinspection PyUnresolvedReferences
        xrange
    except NameError:
        # Python 3
        # noinspection PyShadowingBuiltins


        xrange = range


    from array import array

    class XorMaskerSimple(object):
        __slots__ = ("_ptr", "_msk")

        def __init__(self, mask):
            assert len(mask) == 4
            self._ptr = 0
            self._msk = array("B", mask)

        def pointer(self):
            return self._ptr

        def reset(self):
            self._ptr = 0

        def process(self, data):
            dlen = len(data)
            payload = array("B", data)
            for k in xrange(dlen):
                payload[k] ^= self._msk[self._ptr & 3]
                self._ptr += 1
            return payload.tobytes()

    class XorMaskerShifted1(object):
        __slots__ = ("_ptr", "_mskarray")

        def __init__(self, mask):
            assert len(mask) == 4
            self._ptr = 0
            self._mskarray = [array("B"), array("B"), array("B"), array("B")]
            for j in xrange(4):
                self._mskarray[0].append(mask[j & 3])
                self._mskarray[1].append(mask[(j + 1) & 3])
                self._mskarray[2].append(mask[(j + 2) & 3])
                self._mskarray[3].append(mask[(j + 3) & 3])

        def pointer(self):
            return self._ptr

        def reset(self):
            self._ptr = 0

        def process(self, data):
            dlen = len(data)
            payload = array("B", data)
            msk = self._mskarray[self._ptr & 3]
            for k in xrange(dlen):
                payload[k] ^= msk[k & 3]
            self._ptr += dlen
            return payload.tobytes()

    def create_xor_masker(mask, length=None):
        if length is None or length < 128:
            return XorMaskerSimple(mask)
        else:
            return XorMaskerShifted1(mask)