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# The MIT License (MIT)
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import bz2
from autobahn.websocket.compress_base import (
PerMessageCompress,
PerMessageCompressOffer,
PerMessageCompressOfferAccept,
PerMessageCompressResponse,
PerMessageCompressResponseAccept,
)
__all__ = (
"PerMessageBzip2",
"PerMessageBzip2Mixin",
"PerMessageBzip2Offer",
"PerMessageBzip2OfferAccept",
"PerMessageBzip2Response",
"PerMessageBzip2ResponseAccept",
)
[docs]
class PerMessageBzip2Mixin:
"""
Mixin class for this extension.
"""
[docs]
EXTENSION_NAME = "permessage-bzip2"
"""
Name of this WebSocket extension.
"""
[docs]
COMPRESS_LEVEL_PERMISSIBLE_VALUES = [1, 2, 3, 4, 5, 6, 7, 8, 9]
"""
Permissible value for compression level parameter.
"""
[docs]
class PerMessageBzip2Offer(PerMessageCompressOffer, PerMessageBzip2Mixin):
"""
Set of extension parameters for `permessage-bzip2` WebSocket extension
offered by a client to a server.
"""
@classmethod
[docs]
def parse(cls, params):
"""
Parses a WebSocket extension offer for `permessage-bzip2` 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.PerMessageBzip2Offer`.
"""
# extension parameter defaults
accept_max_compress_level = False
request_max_compress_level = 0
# verify/parse client ("client-to-server direction") parameters of permessage-bzip2 offer
for p in params:
if len(params[p]) > 1:
raise Exception(
f"multiple occurrence of extension parameter '{p}' for extension '{cls.EXTENSION_NAME}'"
)
val = params[p][0]
if p == "client_max_compress_level":
# noinspection PySimplifyBooleanCheck
if val is not True:
raise Exception(
f"illegal extension parameter value '{val}' for parameter '{p}' of extension '{cls.EXTENSION_NAME}'"
)
else:
accept_max_compress_level = True
elif p == "server_max_compress_level":
try:
val = int(val)
except:
raise Exception(
f"illegal extension parameter value '{val}' for parameter '{p}' of extension '{cls.EXTENSION_NAME}'"
)
if val not in PerMessageBzip2Mixin.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
raise Exception(
f"illegal extension parameter value '{val}' for parameter '{p}' of extension '{cls.EXTENSION_NAME}'"
)
else:
request_max_compress_level = val
else:
raise Exception(
f"illegal extension parameter '{p}' for extension '{cls.EXTENSION_NAME}'"
)
offer = cls(accept_max_compress_level, request_max_compress_level)
return offer
def __init__(self, accept_max_compress_level=True, request_max_compress_level=0):
"""
Constructor.
:param accept_max_compress_level: Iff true, client accepts "maximum compression level" parameter.
:type accept_max_compress_level: bool
:param request_max_compress_level: Iff non-zero, client requests given "maximum compression level" - must be 1-9.
:type request_max_compress_level: int
"""
if type(accept_max_compress_level) != bool:
raise Exception(
f"invalid type {type(accept_max_compress_level)} for accept_max_compress_level"
)
[docs]
self.accept_max_compress_level = accept_max_compress_level
if (
request_max_compress_level != 0
and request_max_compress_level not in self.COMPRESS_LEVEL_PERMISSIBLE_VALUES
):
raise Exception(
f"invalid value {request_max_compress_level} for request_max_compress_level - permissible values {self.COMPRESS_LEVEL_PERMISSIBLE_VALUES}"
)
[docs]
self.request_max_compress_level = request_max_compress_level
[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_max_compress_level:
pmce_string += "; client_max_compress_level"
if self.request_max_compress_level != 0:
pmce_string += (
f"; server_max_compress_level={self.request_max_compress_level}"
)
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_max_compress_level": self.accept_max_compress_level,
"request_max_compress_level": self.request_max_compress_level,
}
[docs]
def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
return (
f"PerMessageBzip2Offer(accept_max_compress_level = {self.accept_max_compress_level}, request_max_compress_level = {self.request_max_compress_level})"
)
[docs]
class PerMessageBzip2OfferAccept(PerMessageCompressOfferAccept, PerMessageBzip2Mixin):
"""
Set of parameters with which to accept an `permessage-bzip2` offer
from a client by a server.
"""
def __init__(self, offer, request_max_compress_level=0, compress_level=None):
"""
Constructor.
:param offer: The offer being accepted.
:type offer: Instance of :class:`autobahn.compress.PerMessageBzip2Offer`.
:param request_max_compress_level: Iff non-zero, server requests given "maximum compression level" - must be 1-9.
:type request_max_compress_level: int
:param compress_level: Override server ("server-to-client direction") compress level (this must be compatible with offer).
:type compress_level: int
"""
if not isinstance(offer, PerMessageBzip2Offer):
raise Exception(f"invalid type {type(offer)} for offer")
if (
request_max_compress_level != 0
and request_max_compress_level not in self.COMPRESS_LEVEL_PERMISSIBLE_VALUES
):
raise Exception(
f"invalid value {request_max_compress_level} for request_max_compress_level - permissible values {self.COMPRESS_LEVEL_PERMISSIBLE_VALUES}"
)
if request_max_compress_level != 0 and not offer.accept_max_compress_level:
raise Exception(
f"invalid value {request_max_compress_level} for request_max_compress_level - feature unsupported by client"
)
[docs]
self.request_max_compress_level = request_max_compress_level
if compress_level is not None:
if compress_level not in self.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
raise Exception(
f"invalid value {compress_level} for compress_level - permissible values {self.COMPRESS_LEVEL_PERMISSIBLE_VALUES}"
)
if (
offer.request_max_compress_level != 0
and compress_level > offer.request_max_compress_level
):
raise Exception(
f"invalid value {compress_level} for compress_level - client requested lower maximum value"
)
[docs]
self.compress_level = compress_level
[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_max_compress_level != 0:
pmce_string += (
f"; server_max_compress_level={self.offer.request_max_compress_level}"
)
if self.request_max_compress_level != 0:
pmce_string += (
f"; client_max_compress_level={self.request_max_compress_level}"
)
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_max_compress_level": self.request_max_compress_level,
"compress_level": self.compress_level,
}
[docs]
def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
return (
f"PerMessageBzip2Accept(offer = {self.offer.__repr__()}, request_max_compress_level = {self.request_max_compress_level}, compress_level = {self.compress_level})"
)
[docs]
class PerMessageBzip2Response(PerMessageCompressResponse, PerMessageBzip2Mixin):
"""
Set of parameters for `permessage-bzip2` responded by server.
"""
@classmethod
[docs]
def parse(cls, params):
"""
Parses a WebSocket extension response for `permessage-bzip2` 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.PerMessageBzip2Response`.
:rtype: obj
"""
client_max_compress_level = 0
server_max_compress_level = 0
for p in params:
if len(params[p]) > 1:
raise Exception(
f"multiple occurrence of extension parameter '{p}' for extension '{cls.EXTENSION_NAME}'"
)
val = params[p][0]
if p == "client_max_compress_level":
try:
val = int(val)
except:
raise Exception(
f"illegal extension parameter value '{val}' for parameter '{p}' of extension '{cls.EXTENSION_NAME}'"
)
if val not in PerMessageBzip2Mixin.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
raise Exception(
f"illegal extension parameter value '{val}' for parameter '{p}' of extension '{cls.EXTENSION_NAME}'"
)
else:
client_max_compress_level = val
elif p == "server_max_compress_level":
try:
val = int(val)
except:
raise Exception(
f"illegal extension parameter value '{val}' for parameter '{p}' of extension '{cls.EXTENSION_NAME}'"
)
if val not in PerMessageBzip2Mixin.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
raise Exception(
f"illegal extension parameter value '{val}' for parameter '{p}' of extension '{cls.EXTENSION_NAME}'"
)
else:
server_max_compress_level = val
else:
raise Exception(
f"illegal extension parameter '{p}' for extension '{cls.EXTENSION_NAME}'"
)
response = cls(client_max_compress_level, server_max_compress_level)
return response
def __init__(self, client_max_compress_level, server_max_compress_level):
[docs]
self.client_max_compress_level = client_max_compress_level
[docs]
self.server_max_compress_level = server_max_compress_level
[docs]
def __json__(self):
"""
Returns a JSON serializable object representation.
:returns: JSON serializable representation.
:rtype: dict
"""
return {
"extension": self.EXTENSION_NAME,
"client_max_compress_level": self.client_max_compress_level,
"server_max_compress_level": self.server_max_compress_level,
}
[docs]
def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
return (
f"PerMessageBzip2Response(client_max_compress_level = {self.client_max_compress_level}, server_max_compress_level = {self.server_max_compress_level})"
)
[docs]
class PerMessageBzip2ResponseAccept(
PerMessageCompressResponseAccept, PerMessageBzip2Mixin
):
"""
Set of parameters with which to accept an `permessage-bzip2` response
from a server by a client.
"""
def __init__(self, response, compress_level=None):
"""
:param response: The response being accepted.
:type response: Instance of :class:`autobahn.compress.PerMessageBzip2Response`.
:param compress_level: Override client ("client-to-server direction") compress level (this must be compatible with response).
:type compress_level: int
"""
if not isinstance(response, PerMessageBzip2Response):
raise Exception(f"invalid type {type(response)} for response")
[docs]
self.response = response
if compress_level is not None:
if compress_level not in self.COMPRESS_LEVEL_PERMISSIBLE_VALUES:
raise Exception(
f"invalid value {compress_level} for compress_level - permissible values {self.COMPRESS_LEVEL_PERMISSIBLE_VALUES}"
)
if (
response.client_max_compress_level != 0
and compress_level > response.client_max_compress_level
):
raise Exception(
f"invalid value {compress_level} for compress_level - server requested lower maximum value"
)
[docs]
self.compress_level = compress_level
[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__(),
"compress_level": self.compress_level,
}
[docs]
def __repr__(self):
"""
Returns Python object representation that can be eval'ed to reconstruct the object.
:returns: Python string representation.
:rtype: str
"""
return f"PerMessageBzip2ResponseAccept(response = {self.response.__repr__()}, compress_level = {self.compress_level})"
[docs]
class PerMessageBzip2(PerMessageCompress, PerMessageBzip2Mixin):
"""
`permessage-bzip2` WebSocket extension processor.
"""
[docs]
DEFAULT_COMPRESS_LEVEL = 9
@classmethod
[docs]
def create_from_response_accept(cls, is_server, accept):
pmce = cls(
is_server,
accept.response.server_max_compress_level,
(
accept.compress_level
if accept.compress_level is not None
else accept.response.client_max_compress_level
),
)
return pmce
@classmethod
[docs]
def create_from_offer_accept(cls, is_server, accept):
pmce = cls(
is_server,
(
accept.compress_level
if accept.compress_level is not None
else accept.offer.request_max_compress_level
),
accept.request_max_compress_level,
)
return pmce
def __init__(self, is_server, server_max_compress_level, client_max_compress_level):
[docs]
self._isServer = is_server
[docs]
self._compressor = None
[docs]
self._decompressor = None
[docs]
self.server_max_compress_level = (
server_max_compress_level
if server_max_compress_level != 0
else self.DEFAULT_COMPRESS_LEVEL
)
[docs]
self.client_max_compress_level = (
client_max_compress_level
if client_max_compress_level != 0
else self.DEFAULT_COMPRESS_LEVEL
)
[docs]
def __json__(self):
return {
"extension": self.EXTENSION_NAME,
"isServer": self._isServer,
"server_max_compress_level": self.server_max_compress_level,
"client_max_compress_level": self.client_max_compress_level,
}
[docs]
def __repr__(self):
return (
f"PerMessageBzip2(isServer = {self._isServer}, server_max_compress_level = {self.server_max_compress_level}, client_max_compress_level = {self.client_max_compress_level})"
)
[docs]
def start_compress_message(self):
if self._isServer:
if self._compressor is None:
self._compressor = bz2.BZ2Compressor(self.server_max_compress_level)
else:
if self._compressor is None:
self._compressor = bz2.BZ2Compressor(self.client_max_compress_level)
[docs]
def compress_message_data(self, data):
return self._compressor.compress(data)
[docs]
def end_compress_message(self):
data = self._compressor.flush()
# there seems to be no "flush without close stream", and after
# full flush, compressor must not be reused
self._compressor = None
return data
[docs]
def start_decompress_message(self):
if self._decompressor is None:
self._decompressor = bz2.BZ2Decompressor()
[docs]
def decompress_message_data(self, data):
return self._decompressor.decompress(data)
[docs]
def end_decompress_message(self):
self._decompressor = None