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Diffstat (limited to 'venv/lib/python3.11/site-packages/websockets/server.py')
| -rw-r--r-- | venv/lib/python3.11/site-packages/websockets/server.py | 580 |
1 files changed, 580 insertions, 0 deletions
diff --git a/venv/lib/python3.11/site-packages/websockets/server.py b/venv/lib/python3.11/site-packages/websockets/server.py new file mode 100644 index 0000000..1916605 --- /dev/null +++ b/venv/lib/python3.11/site-packages/websockets/server.py @@ -0,0 +1,580 @@ +from __future__ import annotations + +import base64 +import binascii +import email.utils +import http +import warnings +from typing import Any, Callable, Generator, List, Optional, Sequence, Tuple, cast + +from .datastructures import Headers, MultipleValuesError +from .exceptions import ( + InvalidHandshake, + InvalidHeader, + InvalidHeaderValue, + InvalidOrigin, + InvalidStatus, + InvalidUpgrade, + NegotiationError, +) +from .extensions import Extension, ServerExtensionFactory +from .headers import ( + build_extension, + parse_connection, + parse_extension, + parse_subprotocol, + parse_upgrade, +) +from .http11 import Request, Response +from .protocol import CONNECTING, OPEN, SERVER, Protocol, State +from .typing import ( + ConnectionOption, + ExtensionHeader, + LoggerLike, + Origin, + StatusLike, + Subprotocol, + UpgradeProtocol, +) +from .utils import accept_key + + +# See #940 for why lazy_import isn't used here for backwards compatibility. +# See #1400 for why listing compatibility imports in __all__ helps PyCharm. +from .legacy.server import * # isort:skip # noqa: I001 +from .legacy.server import __all__ as legacy__all__ + + +__all__ = ["ServerProtocol"] + legacy__all__ + + +class ServerProtocol(Protocol): + """ + Sans-I/O implementation of a WebSocket server connection. + + Args: + origins: acceptable values of the ``Origin`` header; include + :obj:`None` in the list if the lack of an origin is acceptable. + This is useful for defending against Cross-Site WebSocket + Hijacking attacks. + extensions: list of supported extensions, in order in which they + should be tried. + subprotocols: list of supported subprotocols, in order of decreasing + preference. + select_subprotocol: Callback for selecting a subprotocol among + those supported by the client and the server. It has the same + signature as the :meth:`select_subprotocol` method, including a + :class:`ServerProtocol` instance as first argument. + state: initial state of the WebSocket connection. + max_size: maximum size of incoming messages in bytes; + :obj:`None` disables the limit. + logger: logger for this connection; + defaults to ``logging.getLogger("websockets.client")``; + see the :doc:`logging guide <../../topics/logging>` for details. + + """ + + def __init__( + self, + *, + origins: Optional[Sequence[Optional[Origin]]] = None, + extensions: Optional[Sequence[ServerExtensionFactory]] = None, + subprotocols: Optional[Sequence[Subprotocol]] = None, + select_subprotocol: Optional[ + Callable[ + [ServerProtocol, Sequence[Subprotocol]], + Optional[Subprotocol], + ] + ] = None, + state: State = CONNECTING, + max_size: Optional[int] = 2**20, + logger: Optional[LoggerLike] = None, + ): + super().__init__( + side=SERVER, + state=state, + max_size=max_size, + logger=logger, + ) + self.origins = origins + self.available_extensions = extensions + self.available_subprotocols = subprotocols + if select_subprotocol is not None: + # Bind select_subprotocol then shadow self.select_subprotocol. + # Use setattr to work around https://github.com/python/mypy/issues/2427. + setattr( + self, + "select_subprotocol", + select_subprotocol.__get__(self, self.__class__), + ) + + def accept(self, request: Request) -> Response: + """ + Create a handshake response to accept the connection. + + If the connection cannot be established, the handshake response + actually rejects the handshake. + + You must send the handshake response with :meth:`send_response`. + + You may modify it before sending it, for example to add HTTP headers. + + Args: + request: WebSocket handshake request event received from the client. + + Returns: + WebSocket handshake response event to send to the client. + + """ + try: + ( + accept_header, + extensions_header, + protocol_header, + ) = self.process_request(request) + except InvalidOrigin as exc: + request._exception = exc + self.handshake_exc = exc + if self.debug: + self.logger.debug("! invalid origin", exc_info=True) + return self.reject( + http.HTTPStatus.FORBIDDEN, + f"Failed to open a WebSocket connection: {exc}.\n", + ) + except InvalidUpgrade as exc: + request._exception = exc + self.handshake_exc = exc + if self.debug: + self.logger.debug("! invalid upgrade", exc_info=True) + response = self.reject( + http.HTTPStatus.UPGRADE_REQUIRED, + ( + f"Failed to open a WebSocket connection: {exc}.\n" + f"\n" + f"You cannot access a WebSocket server directly " + f"with a browser. You need a WebSocket client.\n" + ), + ) + response.headers["Upgrade"] = "websocket" + return response + except InvalidHandshake as exc: + request._exception = exc + self.handshake_exc = exc + if self.debug: + self.logger.debug("! invalid handshake", exc_info=True) + return self.reject( + http.HTTPStatus.BAD_REQUEST, + f"Failed to open a WebSocket connection: {exc}.\n", + ) + except Exception as exc: + # Handle exceptions raised by user-provided select_subprotocol and + # unexpected errors. + request._exception = exc + self.handshake_exc = exc + self.logger.error("opening handshake failed", exc_info=True) + return self.reject( + http.HTTPStatus.INTERNAL_SERVER_ERROR, + ( + "Failed to open a WebSocket connection.\n" + "See server log for more information.\n" + ), + ) + + headers = Headers() + + headers["Date"] = email.utils.formatdate(usegmt=True) + + headers["Upgrade"] = "websocket" + headers["Connection"] = "Upgrade" + headers["Sec-WebSocket-Accept"] = accept_header + + if extensions_header is not None: + headers["Sec-WebSocket-Extensions"] = extensions_header + + if protocol_header is not None: + headers["Sec-WebSocket-Protocol"] = protocol_header + + self.logger.info("connection open") + return Response(101, "Switching Protocols", headers) + + def process_request( + self, + request: Request, + ) -> Tuple[str, Optional[str], Optional[str]]: + """ + Check a handshake request and negotiate extensions and subprotocol. + + This function doesn't verify that the request is an HTTP/1.1 or higher + GET request and doesn't check the ``Host`` header. These controls are + usually performed earlier in the HTTP request handling code. They're + the responsibility of the caller. + + Args: + request: WebSocket handshake request received from the client. + + Returns: + Tuple[str, Optional[str], Optional[str]]: + ``Sec-WebSocket-Accept``, ``Sec-WebSocket-Extensions``, and + ``Sec-WebSocket-Protocol`` headers for the handshake response. + + Raises: + InvalidHandshake: if the handshake request is invalid; + then the server must return 400 Bad Request error. + + """ + headers = request.headers + + connection: List[ConnectionOption] = sum( + [parse_connection(value) for value in headers.get_all("Connection")], [] + ) + + if not any(value.lower() == "upgrade" for value in connection): + raise InvalidUpgrade( + "Connection", ", ".join(connection) if connection else None + ) + + upgrade: List[UpgradeProtocol] = sum( + [parse_upgrade(value) for value in headers.get_all("Upgrade")], [] + ) + + # For compatibility with non-strict implementations, ignore case when + # checking the Upgrade header. The RFC always uses "websocket", except + # in section 11.2. (IANA registration) where it uses "WebSocket". + if not (len(upgrade) == 1 and upgrade[0].lower() == "websocket"): + raise InvalidUpgrade("Upgrade", ", ".join(upgrade) if upgrade else None) + + try: + key = headers["Sec-WebSocket-Key"] + except KeyError as exc: + raise InvalidHeader("Sec-WebSocket-Key") from exc + except MultipleValuesError as exc: + raise InvalidHeader( + "Sec-WebSocket-Key", "more than one Sec-WebSocket-Key header found" + ) from exc + + try: + raw_key = base64.b64decode(key.encode(), validate=True) + except binascii.Error as exc: + raise InvalidHeaderValue("Sec-WebSocket-Key", key) from exc + if len(raw_key) != 16: + raise InvalidHeaderValue("Sec-WebSocket-Key", key) + + try: + version = headers["Sec-WebSocket-Version"] + except KeyError as exc: + raise InvalidHeader("Sec-WebSocket-Version") from exc + except MultipleValuesError as exc: + raise InvalidHeader( + "Sec-WebSocket-Version", + "more than one Sec-WebSocket-Version header found", + ) from exc + + if version != "13": + raise InvalidHeaderValue("Sec-WebSocket-Version", version) + + accept_header = accept_key(key) + + self.origin = self.process_origin(headers) + + extensions_header, self.extensions = self.process_extensions(headers) + + protocol_header = self.subprotocol = self.process_subprotocol(headers) + + return ( + accept_header, + extensions_header, + protocol_header, + ) + + def process_origin(self, headers: Headers) -> Optional[Origin]: + """ + Handle the Origin HTTP request header. + + Args: + headers: WebSocket handshake request headers. + + Returns: + Optional[Origin]: origin, if it is acceptable. + + Raises: + InvalidHandshake: if the Origin header is invalid. + InvalidOrigin: if the origin isn't acceptable. + + """ + # "The user agent MUST NOT include more than one Origin header field" + # per https://www.rfc-editor.org/rfc/rfc6454.html#section-7.3. + try: + origin = cast(Optional[Origin], headers.get("Origin")) + except MultipleValuesError as exc: + raise InvalidHeader("Origin", "more than one Origin header found") from exc + if self.origins is not None: + if origin not in self.origins: + raise InvalidOrigin(origin) + return origin + + def process_extensions( + self, + headers: Headers, + ) -> Tuple[Optional[str], List[Extension]]: + """ + Handle the Sec-WebSocket-Extensions HTTP request header. + + Accept or reject each extension proposed in the client request. + Negotiate parameters for accepted extensions. + + Per :rfc:`6455`, negotiation rules are defined by the specification of + each extension. + + To provide this level of flexibility, for each extension proposed by + the client, we check for a match with each extension available in the + server configuration. If no match is found, the extension is ignored. + + If several variants of the same extension are proposed by the client, + it may be accepted several times, which won't make sense in general. + Extensions must implement their own requirements. For this purpose, + the list of previously accepted extensions is provided. + + This process doesn't allow the server to reorder extensions. It can + only select a subset of the extensions proposed by the client. + + Other requirements, for example related to mandatory extensions or the + order of extensions, may be implemented by overriding this method. + + Args: + headers: WebSocket handshake request headers. + + Returns: + Tuple[Optional[str], List[Extension]]: ``Sec-WebSocket-Extensions`` + HTTP response header and list of accepted extensions. + + Raises: + InvalidHandshake: if the Sec-WebSocket-Extensions header is invalid. + + """ + response_header_value: Optional[str] = None + + extension_headers: List[ExtensionHeader] = [] + accepted_extensions: List[Extension] = [] + + header_values = headers.get_all("Sec-WebSocket-Extensions") + + if header_values and self.available_extensions: + parsed_header_values: List[ExtensionHeader] = sum( + [parse_extension(header_value) for header_value in header_values], [] + ) + + for name, request_params in parsed_header_values: + for ext_factory in self.available_extensions: + # Skip non-matching extensions based on their name. + if ext_factory.name != name: + continue + + # Skip non-matching extensions based on their params. + try: + response_params, extension = ext_factory.process_request_params( + request_params, accepted_extensions + ) + except NegotiationError: + continue + + # Add matching extension to the final list. + extension_headers.append((name, response_params)) + accepted_extensions.append(extension) + + # Break out of the loop once we have a match. + break + + # If we didn't break from the loop, no extension in our list + # matched what the client sent. The extension is declined. + + # Serialize extension header. + if extension_headers: + response_header_value = build_extension(extension_headers) + + return response_header_value, accepted_extensions + + def process_subprotocol(self, headers: Headers) -> Optional[Subprotocol]: + """ + Handle the Sec-WebSocket-Protocol HTTP request header. + + Args: + headers: WebSocket handshake request headers. + + Returns: + Optional[Subprotocol]: Subprotocol, if one was selected; this is + also the value of the ``Sec-WebSocket-Protocol`` response header. + + Raises: + InvalidHandshake: if the Sec-WebSocket-Subprotocol header is invalid. + + """ + subprotocols: Sequence[Subprotocol] = sum( + [ + parse_subprotocol(header_value) + for header_value in headers.get_all("Sec-WebSocket-Protocol") + ], + [], + ) + + return self.select_subprotocol(subprotocols) + + def select_subprotocol( + self, + subprotocols: Sequence[Subprotocol], + ) -> Optional[Subprotocol]: + """ + Pick a subprotocol among those offered by the client. + + If several subprotocols are supported by both the client and the server, + pick the first one in the list declared the server. + + If the server doesn't support any subprotocols, continue without a + subprotocol, regardless of what the client offers. + + If the server supports at least one subprotocol and the client doesn't + offer any, abort the handshake with an HTTP 400 error. + + You provide a ``select_subprotocol`` argument to :class:`ServerProtocol` + to override this logic. For example, you could accept the connection + even if client doesn't offer a subprotocol, rather than reject it. + + Here's how to negotiate the ``chat`` subprotocol if the client supports + it and continue without a subprotocol otherwise:: + + def select_subprotocol(protocol, subprotocols): + if "chat" in subprotocols: + return "chat" + + Args: + subprotocols: list of subprotocols offered by the client. + + Returns: + Optional[Subprotocol]: Selected subprotocol, if a common subprotocol + was found. + + :obj:`None` to continue without a subprotocol. + + Raises: + NegotiationError: custom implementations may raise this exception + to abort the handshake with an HTTP 400 error. + + """ + # Server doesn't offer any subprotocols. + if not self.available_subprotocols: # None or empty list + return None + + # Server offers at least one subprotocol but client doesn't offer any. + if not subprotocols: + raise NegotiationError("missing subprotocol") + + # Server and client both offer subprotocols. Look for a shared one. + proposed_subprotocols = set(subprotocols) + for subprotocol in self.available_subprotocols: + if subprotocol in proposed_subprotocols: + return subprotocol + + # No common subprotocol was found. + raise NegotiationError( + "invalid subprotocol; expected one of " + + ", ".join(self.available_subprotocols) + ) + + def reject( + self, + status: StatusLike, + text: str, + ) -> Response: + """ + Create a handshake response to reject the connection. + + A short plain text response is the best fallback when failing to + establish a WebSocket connection. + + You must send the handshake response with :meth:`send_response`. + + You can modify it before sending it, for example to alter HTTP headers. + + Args: + status: HTTP status code. + text: HTTP response body; will be encoded to UTF-8. + + Returns: + Response: WebSocket handshake response event to send to the client. + + """ + # If a user passes an int instead of a HTTPStatus, fix it automatically. + status = http.HTTPStatus(status) + body = text.encode() + headers = Headers( + [ + ("Date", email.utils.formatdate(usegmt=True)), + ("Connection", "close"), + ("Content-Length", str(len(body))), + ("Content-Type", "text/plain; charset=utf-8"), + ] + ) + response = Response(status.value, status.phrase, headers, body) + # When reject() is called from accept(), handshake_exc is already set. + # If a user calls reject(), set handshake_exc to guarantee invariant: + # "handshake_exc is None if and only if opening handshake succeeded." + if self.handshake_exc is None: + self.handshake_exc = InvalidStatus(response) + self.logger.info("connection rejected (%d %s)", status.value, status.phrase) + return response + + def send_response(self, response: Response) -> None: + """ + Send a handshake response to the client. + + Args: + response: WebSocket handshake response event to send. + + """ + if self.debug: + code, phrase = response.status_code, response.reason_phrase + self.logger.debug("> HTTP/1.1 %d %s", code, phrase) + for key, value in response.headers.raw_items(): + self.logger.debug("> %s: %s", key, value) + if response.body is not None: + self.logger.debug("> [body] (%d bytes)", len(response.body)) + + self.writes.append(response.serialize()) + + if response.status_code == 101: + assert self.state is CONNECTING + self.state = OPEN + else: + self.send_eof() + self.parser = self.discard() + next(self.parser) # start coroutine + + def parse(self) -> Generator[None, None, None]: + if self.state is CONNECTING: + try: + request = yield from Request.parse( + self.reader.read_line, + ) + except Exception as exc: + self.handshake_exc = exc + self.send_eof() + self.parser = self.discard() + next(self.parser) # start coroutine + yield + + if self.debug: + self.logger.debug("< GET %s HTTP/1.1", request.path) + for key, value in request.headers.raw_items(): + self.logger.debug("< %s: %s", key, value) + + self.events.append(request) + + yield from super().parse() + + +class ServerConnection(ServerProtocol): + def __init__(self, *args: Any, **kwargs: Any) -> None: + warnings.warn( + "ServerConnection was renamed to ServerProtocol", + DeprecationWarning, + ) + super().__init__(*args, **kwargs) |