###############################################################################
##
## Copyright 2013 Tavendo GmbH
##
## Licensed under the Apache License, Version 2.0 (the "License");
## you may not use this file except in compliance with the License.
## You may obtain a copy of the License at
##
## http://www.apache.org/licenses/LICENSE-2.0
##
## Unless required by applicable law or agreed to in writing, software
## distributed under the License is distributed on an "AS IS" BASIS,
## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
## See the License for the specific language governing permissions and
## limitations under the License.
##
###############################################################################
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