316 lines
11 KiB
Python
316 lines
11 KiB
Python
|
"""
|
||
|
|
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}
|