Source code for autobahn.websocket.compress_deflate

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from __future__ import absolute_import


__all__ = (
   'PerMessageDeflateMixin',
   'PerMessageDeflateOffer',
   'PerMessageDeflateOfferAccept',
   'PerMessageDeflateResponse',
   'PerMessageDeflateResponseAccept',
   'PerMessageDeflate',
)


import zlib

from autobahn.websocket.compress_base import PerMessageCompressOffer, \
                                             PerMessageCompressOfferAccept, \
                                             PerMessageCompressResponse, \
                                             PerMessageCompressResponseAccept, \
                                             PerMessageCompress


[docs]class PerMessageDeflateMixin: """ Mixin class for this extension. """ EXTENSION_NAME = "permessage-deflate" """ Name of this WebSocket extension. """ WINDOW_SIZE_PERMISSIBLE_VALUES = [8, 9, 10, 11, 12, 13, 14, 15] """ Permissible value for window size parameter. Higher values use more memory, but produce smaller output. The default is 15. """ MEM_LEVEL_PERMISSIBLE_VALUES = [1, 2, 3, 4, 5, 6, 7, 8, 9] """ Permissible value for memory level parameter. Higher values use more memory, but are faster and produce smaller output. The default is 8. """
[docs]class PerMessageDeflateOffer(PerMessageCompressOffer, PerMessageDeflateMixin): """ Set of extension parameters for `permessage-deflate` WebSocket extension offered by a client to a server. """ @classmethod
[docs] def parse(cls, params): """ Parses a WebSocket extension offer for `permessage-deflate` provided by a client to a server. :param params: Output from :func:`autobahn.websocket.WebSocketProtocol._parseExtensionsHeader`. :type params: list :returns: object -- A new instance of :class:`autobahn.compress.PerMessageDeflateOffer`. """ ## extension parameter defaults ## acceptMaxWindowBits = False acceptNoContextTakeover = True #acceptNoContextTakeover = False # FIXME: this may change in draft requestMaxWindowBits = 0 requestNoContextTakeover = False ## ## verify/parse client ("client-to-server direction") parameters of permessage-deflate offer ## for p in params: if len(params[p]) > 1: raise Exception("multiple occurrence of extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME)) val = params[p][0] if p == 'client_max_window_bits': ## ## see: https://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-18 ## 8.1.2.2. client_max_window_bits ## ## ".. This parameter has no value or a decimal integer value without ## leading zeroes between 8 to 15 inclusive .."" ## # noinspection PySimplifyBooleanCheck if val != True: try: val = int(val) except: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: if val not in PerMessageDeflateMixin.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: # FIXME (maybe): possibly forward/process the client hint! #acceptMaxWindowBits = val acceptMaxWindowBits = True else: acceptMaxWindowBits = True elif p == 'client_no_context_takeover': # noinspection PySimplifyBooleanCheck if val != True: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: acceptNoContextTakeover = True elif p == 'server_max_window_bits': try: val = int(val) except: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: if val not in PerMessageDeflateMixin.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: requestMaxWindowBits = val elif p == 'server_no_context_takeover': # noinspection PySimplifyBooleanCheck if val != True: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: requestNoContextTakeover = True else: raise Exception("illegal extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME)) offer = cls(acceptNoContextTakeover, acceptMaxWindowBits, requestNoContextTakeover, requestMaxWindowBits) return offer
def __init__(self, acceptNoContextTakeover = True, acceptMaxWindowBits = True, requestNoContextTakeover = False, requestMaxWindowBits = 0): """ Constructor. :param acceptNoContextTakeover: Iff true, client accepts "no context takeover" feature. :type acceptNoContextTakeover: bool :param acceptMaxWindowBits: Iff true, client accepts setting "max window size". :type acceptMaxWindowBits: bool :param requestNoContextTakeover: Iff true, client request "no context takeover" feature. :type requestNoContextTakeover: bool :param requestMaxWindowBits: Iff non-zero, client requests given "max window size" - must be 8-15. :type requestMaxWindowBits: int """ if type(acceptNoContextTakeover) != bool: raise Exception("invalid type %s for acceptNoContextTakeover" % type(acceptNoContextTakeover)) self.acceptNoContextTakeover = acceptNoContextTakeover if type(acceptMaxWindowBits) != bool: raise Exception("invalid type %s for acceptMaxWindowBits" % type(acceptMaxWindowBits)) self.acceptMaxWindowBits = acceptMaxWindowBits if type(requestNoContextTakeover) != bool: raise Exception("invalid type %s for requestNoContextTakeover" % type(requestNoContextTakeover)) self.requestNoContextTakeover = requestNoContextTakeover if requestMaxWindowBits != 0 and requestMaxWindowBits not in self.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("invalid value %s for requestMaxWindowBits - permissible values %s" % (requestMaxWindowBits, self.WINDOW_SIZE_PERMISSIBLE_VALUES)) self.requestMaxWindowBits = requestMaxWindowBits
[docs] def getExtensionString(self): """ Returns the WebSocket extension configuration string as sent to the server. :returns: str -- PMCE configuration string. """ pmceString = self.EXTENSION_NAME if self.acceptNoContextTakeover: pmceString += "; client_no_context_takeover" if self.acceptMaxWindowBits: pmceString += "; client_max_window_bits" if self.requestNoContextTakeover: pmceString += "; server_no_context_takeover" if self.requestMaxWindowBits != 0: pmceString += "; server_max_window_bits=%d" % self.requestMaxWindowBits return pmceString
def __json__(self): """ Returns a JSON serializable object representation. :returns: object -- JSON serializable representation. """ return {'extension': self.EXTENSION_NAME, 'acceptNoContextTakeover': self.acceptNoContextTakeover, 'acceptMaxWindowBits': self.acceptMaxWindowBits, 'requestNoContextTakeover': self.requestNoContextTakeover, 'requestMaxWindowBits': self.requestMaxWindowBits} def __repr__(self): """ Returns Python object representation that can be eval'ed to reconstruct the object. :returns: str -- Python string representation. """ return "PerMessageDeflateOffer(acceptNoContextTakeover = %s, acceptMaxWindowBits = %s, requestNoContextTakeover = %s, requestMaxWindowBits = %s)" % (self.acceptNoContextTakeover, self.acceptMaxWindowBits, self.requestNoContextTakeover, self.requestMaxWindowBits)
[docs]class PerMessageDeflateOfferAccept(PerMessageCompressOfferAccept, PerMessageDeflateMixin): """ Set of parameters with which to accept an `permessage-deflate` offer from a client by a server. """ def __init__(self, offer, requestNoContextTakeover = False, requestMaxWindowBits = 0, noContextTakeover = None, windowBits = None, memLevel = None): """ Constructor. :param offer: The offer being accepted. :type offer: Instance of :class:`autobahn.compress.PerMessageDeflateOffer`. :param requestNoContextTakeover: Iff true, server request "no context takeover" feature. :type requestNoContextTakeover: bool :param requestMaxCompressLevel: Iff non-zero, server requests given "maximum compression level" - must be 1-9. :type requestMaxCompressLevel: int :param noContextTakeover: Override server ("server-to-client direction") context takeover (this must be compatible with offer). :type noContextTakeover: bool :param windowBits: Override server ("server-to-client direction") window size (this must be compatible with offer). :type windowBits: int :param memLevel: Set server ("server-to-client direction") memory level. :type memLevel: int """ if not isinstance(offer, PerMessageDeflateOffer): raise Exception("invalid type %s for offer" % type(offer)) self.offer = offer if type(requestNoContextTakeover) != bool: raise Exception("invalid type %s for requestNoContextTakeover" % type(requestNoContextTakeover)) if requestNoContextTakeover and not offer.acceptNoContextTakeover: raise Exception("invalid value %s for requestNoContextTakeover - feature unsupported by client" % requestNoContextTakeover) self.requestNoContextTakeover = requestNoContextTakeover if requestMaxWindowBits != 0 and requestMaxWindowBits not in self.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("invalid value %s for requestMaxWindowBits - permissible values %s" % (requestMaxWindowBits, self.WINDOW_SIZE_PERMISSIBLE_VALUES)) if requestMaxWindowBits != 0 and not offer.acceptMaxWindowBits: raise Exception("invalid value %s for requestMaxWindowBits - feature unsupported by client" % requestMaxWindowBits) self.requestMaxWindowBits = requestMaxWindowBits if noContextTakeover is not None: if type(noContextTakeover) != bool: raise Exception("invalid type %s for noContextTakeover" % type(noContextTakeover)) if offer.requestNoContextTakeover and not noContextTakeover: raise Exception("invalid value %s for noContextTakeover - client requested feature" % noContextTakeover) self.noContextTakeover = noContextTakeover if windowBits is not None: if windowBits not in self.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("invalid value %s for windowBits - permissible values %s" % (windowBits, self.WINDOW_SIZE_PERMISSIBLE_VALUES)) if offer.requestMaxWindowBits != 0 and windowBits > offer.requestMaxWindowBits: raise Exception("invalid value %s for windowBits - client requested lower maximum value" % windowBits) self.windowBits = windowBits if memLevel is not None: if memLevel not in self.MEM_LEVEL_PERMISSIBLE_VALUES: raise Exception("invalid value %s for memLevel - permissible values %s" % (memLevel, self.MEM_LEVEL_PERMISSIBLE_VALUES)) self.memLevel = memLevel
[docs] def getExtensionString(self): """ Returns the WebSocket extension configuration string as sent to the server. :returns: str -- PMCE configuration string. """ pmceString = self.EXTENSION_NAME if self.offer.requestNoContextTakeover: pmceString += "; server_no_context_takeover" if self.offer.requestMaxWindowBits != 0: pmceString += "; server_max_window_bits=%d" % self.offer.requestMaxWindowBits if self.requestNoContextTakeover: pmceString += "; client_no_context_takeover" if self.requestMaxWindowBits != 0: pmceString += "; client_max_window_bits=%d" % self.requestMaxWindowBits return pmceString
def __json__(self): """ Returns a JSON serializable object representation. :returns: object -- JSON serializable representation. """ return {'extension': self.EXTENSION_NAME, 'offer': self.offer.__json__(), 'requestNoContextTakeover': self.requestNoContextTakeover, 'requestMaxWindowBits': self.requestMaxWindowBits, 'noContextTakeover': self.noContextTakeover, 'windowBits': self.windowBits, 'memLevel': self.memLevel} def __repr__(self): """ Returns Python object representation that can be eval'ed to reconstruct the object. :returns: str -- Python string representation. """ return "PerMessageDeflateOfferAccept(offer = %s, requestNoContextTakeover = %s, requestMaxWindowBits = %s, noContextTakeover = %s, windowBits = %s, memLevel = %s)" % (self.offer.__repr__(), self.requestNoContextTakeover, self.requestMaxWindowBits, self.noContextTakeover, self.windowBits, self.memLevel)
[docs]class PerMessageDeflateResponse(PerMessageCompressResponse, PerMessageDeflateMixin): """ Set of parameters for `permessage-deflate` responded by server. """ @classmethod
[docs] def parse(cls, params): """ Parses a WebSocket extension response for `permessage-deflate` provided by a server to a client. :param params: Output from :func:`autobahn.websocket.WebSocketProtocol._parseExtensionsHeader`. :type params: list :returns: object -- A new instance of :class:`autobahn.compress.PerMessageDeflateResponse`. """ client_max_window_bits = 0 client_no_context_takeover = False server_max_window_bits = 0 server_no_context_takeover = False for p in params: if len(params[p]) > 1: raise Exception("multiple occurrence of extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME)) val = params[p][0] if p == 'client_max_window_bits': try: val = int(val) except: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: if val not in PerMessageDeflateMixin.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: client_max_window_bits = val elif p == 'client_no_context_takeover': # noinspection PySimplifyBooleanCheck if val != True: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: client_no_context_takeover = True elif p == 'server_max_window_bits': try: val = int(val) except: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: if val not in PerMessageDeflateMixin.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: server_max_window_bits = val elif p == 'server_no_context_takeover': # noinspection PySimplifyBooleanCheck if val != True: raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME)) else: server_no_context_takeover = True else: raise Exception("illegal extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME)) response = cls(client_max_window_bits, client_no_context_takeover, server_max_window_bits, server_no_context_takeover) return response
def __init__(self, client_max_window_bits, client_no_context_takeover, server_max_window_bits, server_no_context_takeover): self.client_max_window_bits = client_max_window_bits self.client_no_context_takeover = client_no_context_takeover self.server_max_window_bits = server_max_window_bits self.server_no_context_takeover = server_no_context_takeover def __json__(self): """ Returns a JSON serializable object representation. :returns: object -- JSON serializable representation. """ return {'extension': self.EXTENSION_NAME, 'client_max_window_bits': self.client_max_window_bits, 'client_no_context_takeover': self.client_no_context_takeover, 'server_max_window_bits': self.server_max_window_bits, 'server_no_context_takeover': self.server_no_context_takeover} def __repr__(self): """ Returns Python object representation that can be eval'ed to reconstruct the object. :returns: str -- Python string representation. """ return "PerMessageDeflateResponse(client_max_window_bits = %s, client_no_context_takeover = %s, server_max_window_bits = %s, server_no_context_takeover = %s)" % (self.client_max_window_bits, self.client_no_context_takeover, self.server_max_window_bits, self.server_no_context_takeover)
[docs]class PerMessageDeflateResponseAccept(PerMessageCompressResponseAccept, PerMessageDeflateMixin): """ Set of parameters with which to accept an `permessage-deflate` response from a server by a client. """ def __init__(self, response, noContextTakeover = None, windowBits = None, memLevel = None): """ Constructor. :param response: The response being accepted. :type response: Instance of :class:`autobahn.compress.PerMessageDeflateResponse`. :param noContextTakeover: Override client ("client-to-server direction") context takeover (this must be compatible with response). :type noContextTakeover: bool :param windowBits: Override client ("client-to-server direction") window size (this must be compatible with response). :type windowBits: int :param memLevel: Set client ("client-to-server direction") memory level. :type memLevel: int """ if not isinstance(response, PerMessageDeflateResponse): raise Exception("invalid type %s for response" % type(response)) self.response = response if noContextTakeover is not None: if type(noContextTakeover) != bool: raise Exception("invalid type %s for noContextTakeover" % type(noContextTakeover)) if response.client_no_context_takeover and not noContextTakeover: raise Exception("invalid value %s for noContextTakeover - server requested feature" % noContextTakeover) self.noContextTakeover = noContextTakeover if windowBits is not None: if windowBits not in self.WINDOW_SIZE_PERMISSIBLE_VALUES: raise Exception("invalid value %s for windowBits - permissible values %s" % (windowBits, self.WINDOW_SIZE_PERMISSIBLE_VALUES)) if response.client_max_window_bits != 0 and windowBits > response.client_max_window_bits: raise Exception("invalid value %s for windowBits - server requested lower maximum value" % windowBits) self.windowBits = windowBits if memLevel is not None: if memLevel not in self.MEM_LEVEL_PERMISSIBLE_VALUES: raise Exception("invalid value %s for memLevel - permissible values %s" % (memLevel, self.MEM_LEVEL_PERMISSIBLE_VALUES)) self.memLevel = memLevel def __json__(self): """ Returns a JSON serializable object representation. :returns: object -- JSON serializable representation. """ return {'extension': self.EXTENSION_NAME, 'response': self.response.__json__(), 'noContextTakeover': self.noContextTakeover, 'windowBits': self.windowBits, 'memLevel': self.memLevel} def __repr__(self): """ Returns Python object representation that can be eval'ed to reconstruct the object. :returns: str -- Python string representation. """ return "PerMessageDeflateResponseAccept(response = %s, noContextTakeover = %s, windowBits = %s, memLevel = %s)" % (self.response.__repr__(), self.noContextTakeover, self.windowBits, self.memLevel)
# noinspection PyArgumentList
[docs]class PerMessageDeflate(PerMessageCompress, PerMessageDeflateMixin): """ `permessage-deflate` WebSocket extension processor. """ DEFAULT_WINDOW_BITS = zlib.MAX_WBITS DEFAULT_MEM_LEVEL = 8 @classmethod
[docs] def createFromResponseAccept(cls, isServer, accept):
## accept: instance of PerMessageDeflateResponseAccept pmce = cls(isServer, accept.response.server_no_context_takeover, accept.noContextTakeover if accept.noContextTakeover is not None else accept.response.client_no_context_takeover, accept.response.server_max_window_bits, accept.windowBits if accept.windowBits is not None else accept.response.client_max_window_bits, accept.memLevel) return pmce @classmethod
[docs] def createFromOfferAccept(cls, isServer, accept):
## accept: instance of PerMessageDeflateOfferAccept pmce = cls(isServer, accept.noContextTakeover if accept.noContextTakeover is not None else accept.offer.requestNoContextTakeover, accept.requestNoContextTakeover, accept.windowBits if accept.windowBits is not None else accept.offer.requestMaxWindowBits, accept.requestMaxWindowBits, accept.memLevel) return pmce def __init__(self, isServer, server_no_context_takeover, client_no_context_takeover, server_max_window_bits, client_max_window_bits, mem_level): self._isServer = isServer self.server_no_context_takeover = server_no_context_takeover self.client_no_context_takeover = client_no_context_takeover self.server_max_window_bits = server_max_window_bits if server_max_window_bits != 0 else self.DEFAULT_WINDOW_BITS self.client_max_window_bits = client_max_window_bits if client_max_window_bits != 0 else self.DEFAULT_WINDOW_BITS self.mem_level = mem_level if mem_level else self.DEFAULT_MEM_LEVEL self._compressor = None self._decompressor = None def __json__(self): return {'extension': self.EXTENSION_NAME, 'isServer': self._isServer, 'server_no_context_takeover': self.server_no_context_takeover, 'client_no_context_takeover': self.client_no_context_takeover, 'server_max_window_bits': self.server_max_window_bits, 'client_max_window_bits': self.client_max_window_bits, 'mem_level': self.mem_level} def __repr__(self): return "PerMessageDeflate(isServer = %s, server_no_context_takeover = %s, client_no_context_takeover = %s, server_max_window_bits = %s, client_max_window_bits = %s, mem_level = %s)" % (self._isServer, self.server_no_context_takeover, self.client_no_context_takeover, self.server_max_window_bits, self.client_max_window_bits, self.mem_level)
[docs] def startCompressMessage(self):
# compressobj([level[, method[, wbits[, memlevel[, strategy]]]]]) # http://bugs.python.org/issue19278 # http://hg.python.org/cpython/rev/c54c8e71b79a # if self._isServer: if self._compressor is None or self.server_no_context_takeover: self._compressor = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION, zlib.DEFLATED, -self.server_max_window_bits, self.mem_level) else: if self._compressor is None or self.client_no_context_takeover: self._compressor = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION, zlib.DEFLATED, -self.client_max_window_bits, self.mem_level)
[docs] def compressMessageData(self, data): return self._compressor.compress(data)
[docs] def endCompressMessage(self): data = self._compressor.flush(zlib.Z_SYNC_FLUSH) return data[:-4]
[docs] def startDecompressMessage(self): if self._isServer: if self._decompressor is None or self.client_no_context_takeover: self._decompressor = zlib.decompressobj(-self.client_max_window_bits) else: if self._decompressor is None or self.server_no_context_takeover: self._decompressor = zlib.decompressobj(-self.server_max_window_bits)
[docs] def decompressMessageData(self, data): return self._decompressor.decompress(data)
[docs] def endDecompressMessage(self):
## Eat stripped LEN and NLEN field of a non-compressed block added ## for Z_SYNC_FLUSH. ## self._decompressor.decompress(b'\x00\x00\xff\xff')
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