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Your IP : 216.73.216.190
"""
wsproto/extensions
~~~~~~~~~~~~~~~~~~
WebSocket extensions.
"""
import zlib
from typing import Optional, Tuple, Union
from .frame_protocol import CloseReason, FrameDecoder, FrameProtocol, Opcode, RsvBits
class Extension:
name: str
def enabled(self) -> bool:
return False
def offer(self) -> Union[bool, str]:
pass
def accept(self, offer: str) -> Optional[Union[bool, str]]:
pass
def finalize(self, offer: str) -> None:
pass
def frame_inbound_header(
self,
proto: Union[FrameDecoder, FrameProtocol],
opcode: Opcode,
rsv: RsvBits,
payload_length: int,
) -> Union[CloseReason, RsvBits]:
return RsvBits(False, False, False)
def frame_inbound_payload_data(
self, proto: Union[FrameDecoder, FrameProtocol], data: bytes
) -> Union[bytes, CloseReason]:
return data
def frame_inbound_complete(
self, proto: Union[FrameDecoder, FrameProtocol], fin: bool
) -> Union[bytes, CloseReason, None]:
pass
def frame_outbound(
self,
proto: Union[FrameDecoder, FrameProtocol],
opcode: Opcode,
rsv: RsvBits,
data: bytes,
fin: bool,
) -> Tuple[RsvBits, bytes]:
return (rsv, data)
class PerMessageDeflate(Extension):
name = "permessage-deflate"
DEFAULT_CLIENT_MAX_WINDOW_BITS = 15
DEFAULT_SERVER_MAX_WINDOW_BITS = 15
def __init__(
self,
client_no_context_takeover: bool = False,
client_max_window_bits: Optional[int] = None,
server_no_context_takeover: bool = False,
server_max_window_bits: Optional[int] = None,
) -> None:
self.client_no_context_takeover = client_no_context_takeover
self.server_no_context_takeover = server_no_context_takeover
self._client_max_window_bits = self.DEFAULT_CLIENT_MAX_WINDOW_BITS
self._server_max_window_bits = self.DEFAULT_SERVER_MAX_WINDOW_BITS
if client_max_window_bits is not None:
self.client_max_window_bits = client_max_window_bits
if server_max_window_bits is not None:
self.server_max_window_bits = server_max_window_bits
self._compressor: Optional[zlib._Compress] = None # noqa
self._decompressor: Optional[zlib._Decompress] = None # noqa
# This refers to the current frame
self._inbound_is_compressible: Optional[bool] = None
# This refers to the ongoing message (which might span multiple
# frames). Only the first frame in a fragmented message is flagged for
# compression, so this carries that bit forward.
self._inbound_compressed: Optional[bool] = None
self._enabled = False
@property
def client_max_window_bits(self) -> int:
return self._client_max_window_bits
@client_max_window_bits.setter
def client_max_window_bits(self, value: int) -> None:
if value < 9 or value > 15:
raise ValueError("Window size must be between 9 and 15 inclusive")
self._client_max_window_bits = value
@property
def server_max_window_bits(self) -> int:
return self._server_max_window_bits
@server_max_window_bits.setter
def server_max_window_bits(self, value: int) -> None:
if value < 9 or value > 15:
raise ValueError("Window size must be between 9 and 15 inclusive")
self._server_max_window_bits = value
def _compressible_opcode(self, opcode: Opcode) -> bool:
return opcode in (Opcode.TEXT, Opcode.BINARY, Opcode.CONTINUATION)
def enabled(self) -> bool:
return self._enabled
def offer(self) -> Union[bool, str]:
parameters = [
"client_max_window_bits=%d" % self.client_max_window_bits,
"server_max_window_bits=%d" % self.server_max_window_bits,
]
if self.client_no_context_takeover:
parameters.append("client_no_context_takeover")
if self.server_no_context_takeover:
parameters.append("server_no_context_takeover")
return "; ".join(parameters)
def finalize(self, offer: str) -> None:
bits = [b.strip() for b in offer.split(";")]
for bit in bits[1:]:
if bit.startswith("client_no_context_takeover"):
self.client_no_context_takeover = True
elif bit.startswith("server_no_context_takeover"):
self.server_no_context_takeover = True
elif bit.startswith("client_max_window_bits"):
self.client_max_window_bits = int(bit.split("=", 1)[1].strip())
elif bit.startswith("server_max_window_bits"):
self.server_max_window_bits = int(bit.split("=", 1)[1].strip())
self._enabled = True
def _parse_params(self, params: str) -> Tuple[Optional[int], Optional[int]]:
client_max_window_bits = None
server_max_window_bits = None
bits = [b.strip() for b in params.split(";")]
for bit in bits[1:]:
if bit.startswith("client_no_context_takeover"):
self.client_no_context_takeover = True
elif bit.startswith("server_no_context_takeover"):
self.server_no_context_takeover = True
elif bit.startswith("client_max_window_bits"):
if "=" in bit:
client_max_window_bits = int(bit.split("=", 1)[1].strip())
else:
client_max_window_bits = self.client_max_window_bits
elif bit.startswith("server_max_window_bits"):
if "=" in bit:
server_max_window_bits = int(bit.split("=", 1)[1].strip())
else:
server_max_window_bits = self.server_max_window_bits
return client_max_window_bits, server_max_window_bits
def accept(self, offer: str) -> Union[bool, None, str]:
client_max_window_bits, server_max_window_bits = self._parse_params(offer)
parameters = []
if self.client_no_context_takeover:
parameters.append("client_no_context_takeover")
if self.server_no_context_takeover:
parameters.append("server_no_context_takeover")
try:
if client_max_window_bits is not None:
parameters.append("client_max_window_bits=%d" % client_max_window_bits)
self.client_max_window_bits = client_max_window_bits
if server_max_window_bits is not None:
parameters.append("server_max_window_bits=%d" % server_max_window_bits)
self.server_max_window_bits = server_max_window_bits
except ValueError:
return None
else:
self._enabled = True
return "; ".join(parameters)
def frame_inbound_header(
self,
proto: Union[FrameDecoder, FrameProtocol],
opcode: Opcode,
rsv: RsvBits,
payload_length: int,
) -> Union[CloseReason, RsvBits]:
if rsv.rsv1 and opcode.iscontrol():
return CloseReason.PROTOCOL_ERROR
if rsv.rsv1 and opcode is Opcode.CONTINUATION:
return CloseReason.PROTOCOL_ERROR
self._inbound_is_compressible = self._compressible_opcode(opcode)
if self._inbound_compressed is None:
self._inbound_compressed = rsv.rsv1
if self._inbound_compressed:
assert self._inbound_is_compressible
if proto.client:
bits = self.server_max_window_bits
else:
bits = self.client_max_window_bits
if self._decompressor is None:
self._decompressor = zlib.decompressobj(-int(bits))
return RsvBits(True, False, False)
def frame_inbound_payload_data(
self, proto: Union[FrameDecoder, FrameProtocol], data: bytes
) -> Union[bytes, CloseReason]:
if not self._inbound_compressed or not self._inbound_is_compressible:
return data
assert self._decompressor is not None
try:
return self._decompressor.decompress(bytes(data))
except zlib.error:
return CloseReason.INVALID_FRAME_PAYLOAD_DATA
def frame_inbound_complete(
self, proto: Union[FrameDecoder, FrameProtocol], fin: bool
) -> Union[bytes, CloseReason, None]:
if not fin:
return None
if not self._inbound_is_compressible:
self._inbound_compressed = None
return None
if not self._inbound_compressed:
self._inbound_compressed = None
return None
assert self._decompressor is not None
try:
data = self._decompressor.decompress(b"\x00\x00\xff\xff")
data += self._decompressor.flush()
except zlib.error:
return CloseReason.INVALID_FRAME_PAYLOAD_DATA
if proto.client:
no_context_takeover = self.server_no_context_takeover
else:
no_context_takeover = self.client_no_context_takeover
if no_context_takeover:
self._decompressor = None
self._inbound_compressed = None
return data
def frame_outbound(
self,
proto: Union[FrameDecoder, FrameProtocol],
opcode: Opcode,
rsv: RsvBits,
data: bytes,
fin: bool,
) -> Tuple[RsvBits, bytes]:
if not self._compressible_opcode(opcode):
return (rsv, data)
if opcode is not Opcode.CONTINUATION:
rsv = RsvBits(True, *rsv[1:])
if self._compressor is None:
assert opcode is not Opcode.CONTINUATION
if proto.client:
bits = self.client_max_window_bits
else:
bits = self.server_max_window_bits
self._compressor = zlib.compressobj(
zlib.Z_DEFAULT_COMPRESSION, zlib.DEFLATED, -int(bits)
)
data = self._compressor.compress(bytes(data))
if fin:
data += self._compressor.flush(zlib.Z_SYNC_FLUSH)
data = data[:-4]
if proto.client:
no_context_takeover = self.client_no_context_takeover
else:
no_context_takeover = self.server_no_context_takeover
if no_context_takeover:
self._compressor = None
return (rsv, data)
def __repr__(self) -> str:
descr = ["client_max_window_bits=%d" % self.client_max_window_bits]
if self.client_no_context_takeover:
descr.append("client_no_context_takeover")
descr.append("server_max_window_bits=%d" % self.server_max_window_bits)
if self.server_no_context_takeover:
descr.append("server_no_context_takeover")
return "<{} {}>".format(self.__class__.__name__, "; ".join(descr))
#: SUPPORTED_EXTENSIONS maps all supported extension names to their class.
#: This can be used to iterate all supported extensions of wsproto, instantiate
#: new extensions based on their name, or check if a given extension is
#: supported or not.
SUPPORTED_EXTENSIONS = {PerMessageDeflate.name: PerMessageDeflate}