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import snappy
from autobahn.websocket.compress_base import PerMessageCompressOffer, \
PerMessageCompressOfferAccept, \
PerMessageCompressResponse, \
PerMessageCompressResponseAccept, \
PerMessageCompress
__all__ = (
'PerMessageSnappyMixin',
'PerMessageSnappyOffer',
'PerMessageSnappyOfferAccept',
'PerMessageSnappyResponse',
'PerMessageSnappyResponseAccept',
'PerMessageSnappy',
)
[docs]class PerMessageSnappyMixin(object):
"""
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.
"""
[docs] @classmethod
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: A new instance of :class:`autobahn.compress.PerMessageSnappyOffer`.
:rtype: obj
"""
# extension parameter defaults
accept_no_context_takeover = False
request_no_context_takeover = 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 is not True:
raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
else:
accept_no_context_takeover = True
elif p == 'server_no_context_takeover':
# noinspection PySimplifyBooleanCheck
if val is not True:
raise Exception("illegal extension parameter value '%s' for parameter '%s' of extension '%s'" % (val, p, cls.EXTENSION_NAME))
else:
request_no_context_takeover = True
else:
raise Exception("illegal extension parameter '%s' for extension '%s'" % (p, cls.EXTENSION_NAME))
offer = cls(accept_no_context_takeover,
request_no_context_takeover)
return offer
def __init__(self,
accept_no_context_takeover=True,
request_no_context_takeover=False):
"""
:param accept_no_context_takeover: Iff true, client accepts "no context takeover" feature.
:type accept_no_context_takeover: bool
:param request_no_context_takeover: Iff true, client request "no context takeover" feature.
:type request_no_context_takeover: bool
"""
if type(accept_no_context_takeover) != bool:
raise Exception("invalid type %s for accept_no_context_takeover" % type(accept_no_context_takeover))
self.accept_no_context_takeover = accept_no_context_takeover
if type(request_no_context_takeover) != bool:
raise Exception("invalid type %s for request_no_context_takeover" % type(request_no_context_takeover))
self.request_no_context_takeover = request_no_context_takeover
[docs] def get_extension_string(self):
"""
Returns the WebSocket extension configuration string as sent to the server.
:returns: PMCE configuration string.
:rtype: str
"""
pmce_string = self.EXTENSION_NAME
if self.accept_no_context_takeover:
pmce_string += "; client_no_context_takeover"
if self.request_no_context_takeover:
pmce_string += "; server_no_context_takeover"
return pmce_string
[docs] def __json__(self):
"""
Returns a JSON serializable object representation.
:returns: JSON serializable representation.
:rtype: dict
"""
return {'extension': self.EXTENSION_NAME,
'accept_no_context_takeover': self.accept_no_context_takeover,
'request_no_context_takeover': self.request_no_context_takeover}
[docs] def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
return "PerMessageSnappyOffer(accept_no_context_takeover = %s, request_no_context_takeover = %s)" % (self.accept_no_context_takeover, self.request_no_context_takeover)
[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,
request_no_context_takeover=False,
no_context_takeover=None):
"""
:param offer: The offer being accepted.
:type offer: Instance of :class:`autobahn.compress.PerMessageSnappyOffer`.
:param request_no_context_takeover: Iff true, server request "no context takeover" feature.
:type request_no_context_takeover: bool
:param no_context_takeover: Override server ("server-to-client direction") context takeover (this must be compatible with offer).
:type no_context_takeover: bool
"""
if not isinstance(offer, PerMessageSnappyOffer):
raise Exception("invalid type %s for offer" % type(offer))
self.offer = offer
if type(request_no_context_takeover) != bool:
raise Exception("invalid type %s for request_no_context_takeover" % type(request_no_context_takeover))
if request_no_context_takeover and not offer.accept_no_context_takeover:
raise Exception("invalid value %s for request_no_context_takeover - feature unsupported by client" % request_no_context_takeover)
self.request_no_context_takeover = request_no_context_takeover
if no_context_takeover is not None:
if type(no_context_takeover) != bool:
raise Exception("invalid type %s for no_context_takeover" % type(no_context_takeover))
if offer.request_no_context_takeover and not no_context_takeover:
raise Exception("invalid value %s for no_context_takeover - client requested feature" % no_context_takeover)
self.no_context_takeover = no_context_takeover
[docs] def get_extension_string(self):
"""
Returns the WebSocket extension configuration string as sent to the server.
:returns: PMCE configuration string.
:rtype: str
"""
pmce_string = self.EXTENSION_NAME
if self.offer.request_no_context_takeover:
pmce_string += "; server_no_context_takeover"
if self.request_no_context_takeover:
pmce_string += "; client_no_context_takeover"
return pmce_string
[docs] def __json__(self):
"""
Returns a JSON serializable object representation.
:returns: JSON serializable representation.
:rtype: dict
"""
return {'extension': self.EXTENSION_NAME,
'offer': self.offer.__json__(),
'request_no_context_takeover': self.request_no_context_takeover,
'no_context_takeover': self.no_context_takeover}
[docs] def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
return "PerMessageSnappyAccept(offer = %s, request_no_context_takeover = %s, no_context_takeover = %s)" % (self.offer.__repr__(), self.request_no_context_takeover, self.no_context_takeover)
[docs]class PerMessageSnappyResponse(PerMessageCompressResponse, PerMessageSnappyMixin):
"""
Set of parameters for `permessage-snappy` responded by server.
"""
[docs] @classmethod
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: A new instance of :class:`autobahn.compress.PerMessageSnappyResponse`.
:rtype: obj
"""
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 is not 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 is not 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
[docs] def __json__(self):
"""
Returns a JSON serializable object representation.
:returns: JSON serializable representation.
:rtype: dict
"""
return {'extension': self.EXTENSION_NAME,
'client_no_context_takeover': self.client_no_context_takeover,
'server_no_context_takeover': self.server_no_context_takeover}
[docs] def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
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,
no_context_takeover=None):
"""
:param response: The response being accepted.
:type response: Instance of :class:`autobahn.compress.PerMessageSnappyResponse`.
:param no_context_takeover: Override client ("client-to-server direction") context takeover (this must be compatible with response).
:type no_context_takeover: bool
"""
if not isinstance(response, PerMessageSnappyResponse):
raise Exception("invalid type %s for response" % type(response))
self.response = response
if no_context_takeover is not None:
if type(no_context_takeover) != bool:
raise Exception("invalid type %s for no_context_takeover" % type(no_context_takeover))
if response.client_no_context_takeover and not no_context_takeover:
raise Exception("invalid value %s for no_context_takeover - server requested feature" % no_context_takeover)
self.no_context_takeover = no_context_takeover
[docs] def __json__(self):
"""
Returns a JSON serializable object representation.
:returns: JSON serializable representation.
:rtype: dict
"""
return {'extension': self.EXTENSION_NAME,
'response': self.response.__json__(),
'no_context_takeover': self.no_context_takeover}
[docs] def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
return "PerMessageSnappyResponseAccept(response = %s, no_context_takeover = %s)" % (self.response.__repr__(), self.no_context_takeover)
[docs]class PerMessageSnappy(PerMessageCompress, PerMessageSnappyMixin):
"""
`permessage-snappy` WebSocket extension processor.
"""
[docs] @classmethod
def create_from_response_accept(cls, is_server, accept):
pmce = cls(is_server,
accept.response.server_no_context_takeover,
accept.no_context_takeover if accept.no_context_takeover is not None else accept.response.client_no_context_takeover)
return pmce
[docs] @classmethod
def create_from_offer_accept(cls, is_server, accept):
pmce = cls(is_server,
accept.no_context_takeover if accept.no_context_takeover is not None else accept.offer.request_no_context_takeover,
accept.request_no_context_takeover)
return pmce
def __init__(self,
is_server,
server_no_context_takeover,
client_no_context_takeover):
self._is_server = is_server
self.server_no_context_takeover = server_no_context_takeover
self.client_no_context_takeover = client_no_context_takeover
self._compressor = None
self._decompressor = None
[docs] 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}
[docs] def __repr__(self):
return "PerMessageSnappy(is_server = %s, server_no_context_takeover = %s, client_no_context_takeover = %s)" % (self._is_server, self.server_no_context_takeover, self.client_no_context_takeover)
[docs] def start_compress_message(self):
if self._is_server:
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 compress_message_data(self, data):
return self._compressor.add_chunk(data)
[docs] def end_compress_message(self):
return b""
[docs] def start_decompress_message(self):
if self._is_server:
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 decompress_message_data(self, data):
return self._decompressor.decompress(data)
[docs] def end_decompress_message(self):
pass