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89 lines
2.8 KiB
89 lines
2.8 KiB
2 years ago
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"""
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wsproto/utilities
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~~~~~~~~~~~~~~~~~
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Utility functions that do not belong in a separate module.
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"""
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import base64
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import hashlib
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import os
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from typing import Dict, List, Optional, Union
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from h11._headers import Headers as H11Headers
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from .events import Event
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from .typing import Headers
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# RFC6455, Section 1.3 - Opening Handshake
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ACCEPT_GUID = b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
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class ProtocolError(Exception):
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pass
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class LocalProtocolError(ProtocolError):
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"""Indicates an error due to local/programming errors.
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This is raised when the connection is asked to do something that
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is either incompatible with the state or the websocket standard.
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"""
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pass # noqa
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class RemoteProtocolError(ProtocolError):
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"""Indicates an error due to the remote's actions.
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This is raised when processing the bytes from the remote if the
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remote has sent data that is incompatible with the websocket
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standard.
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.. attribute:: event_hint
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This is a suggested wsproto Event to send to the client based
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on the error. It could be None if no hint is available.
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"""
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def __init__(self, message: str, event_hint: Optional[Event] = None) -> None:
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self.event_hint = event_hint
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super().__init__(message)
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# Some convenience utilities for working with HTTP headers
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def normed_header_dict(h11_headers: Union[Headers, H11Headers]) -> Dict[bytes, bytes]:
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# This mangles Set-Cookie headers. But it happens that we don't care about
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# any of those, so it's OK. For every other HTTP header, if there are
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# multiple instances then you're allowed to join them together with
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# commas.
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name_to_values: Dict[bytes, List[bytes]] = {}
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for name, value in h11_headers:
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name_to_values.setdefault(name, []).append(value)
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name_to_normed_value = {}
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for name, values in name_to_values.items():
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name_to_normed_value[name] = b", ".join(values)
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return name_to_normed_value
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# We use this for parsing the proposed protocol list, and for parsing the
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# proposed and accepted extension lists. For the proposed protocol list it's
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# fine, because the ABNF is just 1#token. But for the extension lists, it's
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# wrong, because those can contain quoted strings, which can in turn contain
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# commas. XX FIXME
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def split_comma_header(value: bytes) -> List[str]:
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return [piece.decode("ascii").strip() for piece in value.split(b",")]
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def generate_nonce() -> bytes:
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# os.urandom may be overkill for this use case, but I don't think this
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# is a bottleneck, and better safe than sorry...
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return base64.b64encode(os.urandom(16))
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def generate_accept_token(token: bytes) -> bytes:
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accept_token = token + ACCEPT_GUID
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accept_token = hashlib.sha1(accept_token).digest()
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return base64.b64encode(accept_token)
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