Source code for autobahn.websocket.compress_snappy

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##  Copyright 2013 Tavendo GmbH
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##  Licensed under the Apache License, Version 2.0 (the "License");
##  you may not use this file except in compliance with the License.
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##      http://www.apache.org/licenses/LICENSE-2.0
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##  distributed under the License is distributed on an "AS IS" BASIS,
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from __future__ import absolute_import


__all__ = (
   'PerMessageSnappyMixin',
   'PerMessageSnappyOffer',
   'PerMessageSnappyOfferAccept',
   'PerMessageSnappyResponse',
   'PerMessageSnappyResponseAccept',
   'PerMessageSnappy',
)


import snappy

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


[docs]class PerMessageSnappyMixin: """ Mixin class for this extension. """ EXTENSION_NAME = "permessage-snappy" """ Name of this WebSocket extension. """
[docs]class PerMessageSnappyOffer(PerMessageCompressOffer, PerMessageSnappyMixin): """ Set of extension parameters for `permessage-snappy` WebSocket extension offered by a client to a server. """ @classmethod
[docs] def parse(cls, params): """ Parses a WebSocket extension offer for `permessage-snappy` 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.PerMessageSnappyOffer`. """ ## extension parameter defaults ## acceptNoContextTakeover = False requestNoContextTakeover = False ## ## verify/parse client ("client-to-server direction") parameters of permessage-snappy 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_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_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, requestNoContextTakeover) return offer
def __init__(self, acceptNoContextTakeover = True, requestNoContextTakeover = False): """ Constructor. :param acceptNoContextTakeover: Iff true, client accepts "no context takeover" feature. :type acceptNoContextTakeover: bool :param requestNoContextTakeover: Iff true, client request "no context takeover" feature. :type requestNoContextTakeover: bool """ if type(acceptNoContextTakeover) != bool: raise Exception("invalid type %s for acceptNoContextTakeover" % type(acceptNoContextTakeover)) self.acceptNoContextTakeover = acceptNoContextTakeover if type(requestNoContextTakeover) != bool: raise Exception("invalid type %s for requestNoContextTakeover" % type(requestNoContextTakeover)) self.requestNoContextTakeover = requestNoContextTakeover
[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.requestNoContextTakeover: pmceString += "; server_no_context_takeover" return pmceString
def __json__(self): """ Returns a JSON serializable object representation. :returns: object -- JSON serializable representation. """ return {'extension': self.EXTENSION_NAME, 'acceptNoContextTakeover': self.acceptNoContextTakeover, 'requestNoContextTakeover': self.requestNoContextTakeover} def __repr__(self): """ Returns Python object representation that can be eval'ed to reconstruct the object. :returns: str -- Python string representation. """ return "PerMessageSnappyOffer(acceptNoContextTakeover = %s, requestNoContextTakeover = %s)" % (self.acceptNoContextTakeover, self.requestNoContextTakeover)
[docs]class PerMessageSnappyOfferAccept(PerMessageCompressOfferAccept, PerMessageSnappyMixin): """ Set of parameters with which to accept an `permessage-snappy` offer from a client by a server. """ def __init__(self, offer, requestNoContextTakeover = False, noContextTakeover = None): """ Constructor. :param offer: The offer being accepted. :type offer: Instance of :class:`autobahn.compress.PerMessageSnappyOffer`. :param requestNoContextTakeover: Iff true, server request "no context takeover" feature. :type requestNoContextTakeover: bool :param noContextTakeover: Override server ("server-to-client direction") context takeover (this must be compatible with offer). :type noContextTakeover: bool """ if not isinstance(offer, PerMessageSnappyOffer): 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 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
[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.requestNoContextTakeover: pmceString += "; client_no_context_takeover" 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, 'noContextTakeover': self.noContextTakeover} def __repr__(self): """ Returns Python object representation that can be eval'ed to reconstruct the object. :returns: str -- Python string representation. """ return "PerMessageSnappyAccept(offer = %s, requestNoContextTakeover = %s, noContextTakeover = %s)" % (self.offer.__repr__(), self.requestNoContextTakeover, self.noContextTakeover)
[docs]class PerMessageSnappyResponse(PerMessageCompressResponse, PerMessageSnappyMixin): """ Set of parameters for `permessage-snappy` responded by server. """ @classmethod
[docs] def parse(cls, params): """ Parses a WebSocket extension response for `permessage-snappy` 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.PerMessageSnappyResponse`. """ client_no_context_takeover = False 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_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_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_no_context_takeover, server_no_context_takeover) return response
def __init__(self, client_no_context_takeover, server_no_context_takeover): self.client_no_context_takeover = client_no_context_takeover 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_no_context_takeover': self.client_no_context_takeover, '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 "PerMessageSnappyResponse(client_no_context_takeover = %s, server_no_context_takeover = %s)" % (self.client_no_context_takeover, self.server_no_context_takeover)
[docs]class PerMessageSnappyResponseAccept(PerMessageCompressResponseAccept, PerMessageSnappyMixin): """ Set of parameters with which to accept an `permessage-snappy` response from a server by a client. """ def __init__(self, response, noContextTakeover = None): """ Constructor. :param response: The response being accepted. :type response: Instance of :class:`autobahn.compress.PerMessageSnappyResponse`. :param noContextTakeover: Override client ("client-to-server direction") context takeover (this must be compatible with response). :type noContextTakeover: bool """ if not isinstance(response, PerMessageSnappyResponse): 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 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} def __repr__(self): """ Returns Python object representation that can be eval'ed to reconstruct the object. :returns: str -- Python string representation. """ return "PerMessageSnappyResponseAccept(response = %s, noContextTakeover = %s)" % (self.response.__repr__(), self.noContextTakeover)
[docs]class PerMessageSnappy(PerMessageCompress, PerMessageSnappyMixin): """ `permessage-snappy` WebSocket extension processor. """ @classmethod
[docs] def createFromResponseAccept(cls, isServer, accept): pmce = cls(isServer, accept.response.server_no_context_takeover, accept.noContextTakeover if accept.noContextTakeover is not None else accept.response.client_no_context_takeover) return pmce
@classmethod
[docs] def createFromOfferAccept(cls, isServer, accept): pmce = cls(isServer, accept.noContextTakeover if accept.noContextTakeover is not None else accept.offer.requestNoContextTakeover, accept.requestNoContextTakeover) return pmce
def __init__(self, isServer, server_no_context_takeover, client_no_context_takeover): self._isServer = isServer self.server_no_context_takeover = server_no_context_takeover self.client_no_context_takeover = client_no_context_takeover self._compressor = None self._decompressor = None def __json__(self): return {'extension': self.EXTENSION_NAME, 'server_no_context_takeover': self.server_no_context_takeover, 'client_no_context_takeover': self.client_no_context_takeover} def __repr__(self): return "PerMessageSnappy(isServer = %s, server_no_context_takeover = %s, client_no_context_takeover = %s)" % (self._isServer, self.server_no_context_takeover, self.client_no_context_takeover)
[docs] def startCompressMessage(self): if self._isServer: if self._compressor is None or self.server_no_context_takeover: self._compressor = snappy.StreamCompressor() else: if self._compressor is None or self.client_no_context_takeover: self._compressor = snappy.StreamCompressor()
[docs] def compressMessageData(self, data): return self._compressor.add_chunk(data)
[docs] def endCompressMessage(self): return ""
[docs] def startDecompressMessage(self): if self._isServer: if self._decompressor is None or self.client_no_context_takeover: self._decompressor = snappy.StreamDecompressor() else: if self._decompressor is None or self.server_no_context_takeover: self._decompressor = snappy.StreamDecompressor()
[docs] def decompressMessageData(self, data): return self._decompressor.decompress(data)
[docs] def endDecompressMessage(self): pass
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