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Diffstat (limited to '.venv/lib/python3.12/site-packages/h11/_connection.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/h11/_connection.py | 633 |
1 files changed, 633 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/h11/_connection.py b/.venv/lib/python3.12/site-packages/h11/_connection.py new file mode 100644 index 00000000..d1752707 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/h11/_connection.py @@ -0,0 +1,633 @@ +# This contains the main Connection class. Everything in h11 revolves around +# this. +from typing import Any, Callable, cast, Dict, List, Optional, Tuple, Type, Union + +from ._events import ( + ConnectionClosed, + Data, + EndOfMessage, + Event, + InformationalResponse, + Request, + Response, +) +from ._headers import get_comma_header, has_expect_100_continue, set_comma_header +from ._readers import READERS, ReadersType +from ._receivebuffer import ReceiveBuffer +from ._state import ( + _SWITCH_CONNECT, + _SWITCH_UPGRADE, + CLIENT, + ConnectionState, + DONE, + ERROR, + MIGHT_SWITCH_PROTOCOL, + SEND_BODY, + SERVER, + SWITCHED_PROTOCOL, +) +from ._util import ( # Import the internal things we need + LocalProtocolError, + RemoteProtocolError, + Sentinel, +) +from ._writers import WRITERS, WritersType + +# Everything in __all__ gets re-exported as part of the h11 public API. +__all__ = ["Connection", "NEED_DATA", "PAUSED"] + + +class NEED_DATA(Sentinel, metaclass=Sentinel): + pass + + +class PAUSED(Sentinel, metaclass=Sentinel): + pass + + +# If we ever have this much buffered without it making a complete parseable +# event, we error out. The only time we really buffer is when reading the +# request/response line + headers together, so this is effectively the limit on +# the size of that. +# +# Some precedents for defaults: +# - node.js: 80 * 1024 +# - tomcat: 8 * 1024 +# - IIS: 16 * 1024 +# - Apache: <8 KiB per line> +DEFAULT_MAX_INCOMPLETE_EVENT_SIZE = 16 * 1024 + +# RFC 7230's rules for connection lifecycles: +# - If either side says they want to close the connection, then the connection +# must close. +# - HTTP/1.1 defaults to keep-alive unless someone says Connection: close +# - HTTP/1.0 defaults to close unless both sides say Connection: keep-alive +# (and even this is a mess -- e.g. if you're implementing a proxy then +# sending Connection: keep-alive is forbidden). +# +# We simplify life by simply not supporting keep-alive with HTTP/1.0 peers. So +# our rule is: +# - If someone says Connection: close, we will close +# - If someone uses HTTP/1.0, we will close. +def _keep_alive(event: Union[Request, Response]) -> bool: + connection = get_comma_header(event.headers, b"connection") + if b"close" in connection: + return False + if getattr(event, "http_version", b"1.1") < b"1.1": + return False + return True + + +def _body_framing( + request_method: bytes, event: Union[Request, Response] +) -> Tuple[str, Union[Tuple[()], Tuple[int]]]: + # Called when we enter SEND_BODY to figure out framing information for + # this body. + # + # These are the only two events that can trigger a SEND_BODY state: + assert type(event) in (Request, Response) + # Returns one of: + # + # ("content-length", count) + # ("chunked", ()) + # ("http/1.0", ()) + # + # which are (lookup key, *args) for constructing body reader/writer + # objects. + # + # Reference: https://tools.ietf.org/html/rfc7230#section-3.3.3 + # + # Step 1: some responses always have an empty body, regardless of what the + # headers say. + if type(event) is Response: + if ( + event.status_code in (204, 304) + or request_method == b"HEAD" + or (request_method == b"CONNECT" and 200 <= event.status_code < 300) + ): + return ("content-length", (0,)) + # Section 3.3.3 also lists another case -- responses with status_code + # < 200. For us these are InformationalResponses, not Responses, so + # they can't get into this function in the first place. + assert event.status_code >= 200 + + # Step 2: check for Transfer-Encoding (T-E beats C-L): + transfer_encodings = get_comma_header(event.headers, b"transfer-encoding") + if transfer_encodings: + assert transfer_encodings == [b"chunked"] + return ("chunked", ()) + + # Step 3: check for Content-Length + content_lengths = get_comma_header(event.headers, b"content-length") + if content_lengths: + return ("content-length", (int(content_lengths[0]),)) + + # Step 4: no applicable headers; fallback/default depends on type + if type(event) is Request: + return ("content-length", (0,)) + else: + return ("http/1.0", ()) + + +################################################################ +# +# The main Connection class +# +################################################################ + + +class Connection: + """An object encapsulating the state of an HTTP connection. + + Args: + our_role: If you're implementing a client, pass :data:`h11.CLIENT`. If + you're implementing a server, pass :data:`h11.SERVER`. + + max_incomplete_event_size (int): + The maximum number of bytes we're willing to buffer of an + incomplete event. In practice this mostly sets a limit on the + maximum size of the request/response line + headers. If this is + exceeded, then :meth:`next_event` will raise + :exc:`RemoteProtocolError`. + + """ + + def __init__( + self, + our_role: Type[Sentinel], + max_incomplete_event_size: int = DEFAULT_MAX_INCOMPLETE_EVENT_SIZE, + ) -> None: + self._max_incomplete_event_size = max_incomplete_event_size + # State and role tracking + if our_role not in (CLIENT, SERVER): + raise ValueError("expected CLIENT or SERVER, not {!r}".format(our_role)) + self.our_role = our_role + self.their_role: Type[Sentinel] + if our_role is CLIENT: + self.their_role = SERVER + else: + self.their_role = CLIENT + self._cstate = ConnectionState() + + # Callables for converting data->events or vice-versa given the + # current state + self._writer = self._get_io_object(self.our_role, None, WRITERS) + self._reader = self._get_io_object(self.their_role, None, READERS) + + # Holds any unprocessed received data + self._receive_buffer = ReceiveBuffer() + # If this is true, then it indicates that the incoming connection was + # closed *after* the end of whatever's in self._receive_buffer: + self._receive_buffer_closed = False + + # Extra bits of state that don't fit into the state machine. + # + # These two are only used to interpret framing headers for figuring + # out how to read/write response bodies. their_http_version is also + # made available as a convenient public API. + self.their_http_version: Optional[bytes] = None + self._request_method: Optional[bytes] = None + # This is pure flow-control and doesn't at all affect the set of legal + # transitions, so no need to bother ConnectionState with it: + self.client_is_waiting_for_100_continue = False + + @property + def states(self) -> Dict[Type[Sentinel], Type[Sentinel]]: + """A dictionary like:: + + {CLIENT: <client state>, SERVER: <server state>} + + See :ref:`state-machine` for details. + + """ + return dict(self._cstate.states) + + @property + def our_state(self) -> Type[Sentinel]: + """The current state of whichever role we are playing. See + :ref:`state-machine` for details. + """ + return self._cstate.states[self.our_role] + + @property + def their_state(self) -> Type[Sentinel]: + """The current state of whichever role we are NOT playing. See + :ref:`state-machine` for details. + """ + return self._cstate.states[self.their_role] + + @property + def they_are_waiting_for_100_continue(self) -> bool: + return self.their_role is CLIENT and self.client_is_waiting_for_100_continue + + def start_next_cycle(self) -> None: + """Attempt to reset our connection state for a new request/response + cycle. + + If both client and server are in :data:`DONE` state, then resets them + both to :data:`IDLE` state in preparation for a new request/response + cycle on this same connection. Otherwise, raises a + :exc:`LocalProtocolError`. + + See :ref:`keepalive-and-pipelining`. + + """ + old_states = dict(self._cstate.states) + self._cstate.start_next_cycle() + self._request_method = None + # self.their_http_version gets left alone, since it presumably lasts + # beyond a single request/response cycle + assert not self.client_is_waiting_for_100_continue + self._respond_to_state_changes(old_states) + + def _process_error(self, role: Type[Sentinel]) -> None: + old_states = dict(self._cstate.states) + self._cstate.process_error(role) + self._respond_to_state_changes(old_states) + + def _server_switch_event(self, event: Event) -> Optional[Type[Sentinel]]: + if type(event) is InformationalResponse and event.status_code == 101: + return _SWITCH_UPGRADE + if type(event) is Response: + if ( + _SWITCH_CONNECT in self._cstate.pending_switch_proposals + and 200 <= event.status_code < 300 + ): + return _SWITCH_CONNECT + return None + + # All events go through here + def _process_event(self, role: Type[Sentinel], event: Event) -> None: + # First, pass the event through the state machine to make sure it + # succeeds. + old_states = dict(self._cstate.states) + if role is CLIENT and type(event) is Request: + if event.method == b"CONNECT": + self._cstate.process_client_switch_proposal(_SWITCH_CONNECT) + if get_comma_header(event.headers, b"upgrade"): + self._cstate.process_client_switch_proposal(_SWITCH_UPGRADE) + server_switch_event = None + if role is SERVER: + server_switch_event = self._server_switch_event(event) + self._cstate.process_event(role, type(event), server_switch_event) + + # Then perform the updates triggered by it. + + if type(event) is Request: + self._request_method = event.method + + if role is self.their_role and type(event) in ( + Request, + Response, + InformationalResponse, + ): + event = cast(Union[Request, Response, InformationalResponse], event) + self.their_http_version = event.http_version + + # Keep alive handling + # + # RFC 7230 doesn't really say what one should do if Connection: close + # shows up on a 1xx InformationalResponse. I think the idea is that + # this is not supposed to happen. In any case, if it does happen, we + # ignore it. + if type(event) in (Request, Response) and not _keep_alive( + cast(Union[Request, Response], event) + ): + self._cstate.process_keep_alive_disabled() + + # 100-continue + if type(event) is Request and has_expect_100_continue(event): + self.client_is_waiting_for_100_continue = True + if type(event) in (InformationalResponse, Response): + self.client_is_waiting_for_100_continue = False + if role is CLIENT and type(event) in (Data, EndOfMessage): + self.client_is_waiting_for_100_continue = False + + self._respond_to_state_changes(old_states, event) + + def _get_io_object( + self, + role: Type[Sentinel], + event: Optional[Event], + io_dict: Union[ReadersType, WritersType], + ) -> Optional[Callable[..., Any]]: + # event may be None; it's only used when entering SEND_BODY + state = self._cstate.states[role] + if state is SEND_BODY: + # Special case: the io_dict has a dict of reader/writer factories + # that depend on the request/response framing. + framing_type, args = _body_framing( + cast(bytes, self._request_method), cast(Union[Request, Response], event) + ) + return io_dict[SEND_BODY][framing_type](*args) # type: ignore[index] + else: + # General case: the io_dict just has the appropriate reader/writer + # for this state + return io_dict.get((role, state)) # type: ignore[return-value] + + # This must be called after any action that might have caused + # self._cstate.states to change. + def _respond_to_state_changes( + self, + old_states: Dict[Type[Sentinel], Type[Sentinel]], + event: Optional[Event] = None, + ) -> None: + # Update reader/writer + if self.our_state != old_states[self.our_role]: + self._writer = self._get_io_object(self.our_role, event, WRITERS) + if self.their_state != old_states[self.their_role]: + self._reader = self._get_io_object(self.their_role, event, READERS) + + @property + def trailing_data(self) -> Tuple[bytes, bool]: + """Data that has been received, but not yet processed, represented as + a tuple with two elements, where the first is a byte-string containing + the unprocessed data itself, and the second is a bool that is True if + the receive connection was closed. + + See :ref:`switching-protocols` for discussion of why you'd want this. + """ + return (bytes(self._receive_buffer), self._receive_buffer_closed) + + def receive_data(self, data: bytes) -> None: + """Add data to our internal receive buffer. + + This does not actually do any processing on the data, just stores + it. To trigger processing, you have to call :meth:`next_event`. + + Args: + data (:term:`bytes-like object`): + The new data that was just received. + + Special case: If *data* is an empty byte-string like ``b""``, + then this indicates that the remote side has closed the + connection (end of file). Normally this is convenient, because + standard Python APIs like :meth:`file.read` or + :meth:`socket.recv` use ``b""`` to indicate end-of-file, while + other failures to read are indicated using other mechanisms + like raising :exc:`TimeoutError`. When using such an API you + can just blindly pass through whatever you get from ``read`` + to :meth:`receive_data`, and everything will work. + + But, if you have an API where reading an empty string is a + valid non-EOF condition, then you need to be aware of this and + make sure to check for such strings and avoid passing them to + :meth:`receive_data`. + + Returns: + Nothing, but after calling this you should call :meth:`next_event` + to parse the newly received data. + + Raises: + RuntimeError: + Raised if you pass an empty *data*, indicating EOF, and then + pass a non-empty *data*, indicating more data that somehow + arrived after the EOF. + + (Calling ``receive_data(b"")`` multiple times is fine, + and equivalent to calling it once.) + + """ + if data: + if self._receive_buffer_closed: + raise RuntimeError("received close, then received more data?") + self._receive_buffer += data + else: + self._receive_buffer_closed = True + + def _extract_next_receive_event( + self, + ) -> Union[Event, Type[NEED_DATA], Type[PAUSED]]: + state = self.their_state + # We don't pause immediately when they enter DONE, because even in + # DONE state we can still process a ConnectionClosed() event. But + # if we have data in our buffer, then we definitely aren't getting + # a ConnectionClosed() immediately and we need to pause. + if state is DONE and self._receive_buffer: + return PAUSED + if state is MIGHT_SWITCH_PROTOCOL or state is SWITCHED_PROTOCOL: + return PAUSED + assert self._reader is not None + event = self._reader(self._receive_buffer) + if event is None: + if not self._receive_buffer and self._receive_buffer_closed: + # In some unusual cases (basically just HTTP/1.0 bodies), EOF + # triggers an actual protocol event; in that case, we want to + # return that event, and then the state will change and we'll + # get called again to generate the actual ConnectionClosed(). + if hasattr(self._reader, "read_eof"): + event = self._reader.read_eof() # type: ignore[attr-defined] + else: + event = ConnectionClosed() + if event is None: + event = NEED_DATA + return event # type: ignore[no-any-return] + + def next_event(self) -> Union[Event, Type[NEED_DATA], Type[PAUSED]]: + """Parse the next event out of our receive buffer, update our internal + state, and return it. + + This is a mutating operation -- think of it like calling :func:`next` + on an iterator. + + Returns: + : One of three things: + + 1) An event object -- see :ref:`events`. + + 2) The special constant :data:`NEED_DATA`, which indicates that + you need to read more data from your socket and pass it to + :meth:`receive_data` before this method will be able to return + any more events. + + 3) The special constant :data:`PAUSED`, which indicates that we + are not in a state where we can process incoming data (usually + because the peer has finished their part of the current + request/response cycle, and you have not yet called + :meth:`start_next_cycle`). See :ref:`flow-control` for details. + + Raises: + RemoteProtocolError: + The peer has misbehaved. You should close the connection + (possibly after sending some kind of 4xx response). + + Once this method returns :class:`ConnectionClosed` once, then all + subsequent calls will also return :class:`ConnectionClosed`. + + If this method raises any exception besides :exc:`RemoteProtocolError` + then that's a bug -- if it happens please file a bug report! + + If this method raises any exception then it also sets + :attr:`Connection.their_state` to :data:`ERROR` -- see + :ref:`error-handling` for discussion. + + """ + + if self.their_state is ERROR: + raise RemoteProtocolError("Can't receive data when peer state is ERROR") + try: + event = self._extract_next_receive_event() + if event not in [NEED_DATA, PAUSED]: + self._process_event(self.their_role, cast(Event, event)) + if event is NEED_DATA: + if len(self._receive_buffer) > self._max_incomplete_event_size: + # 431 is "Request header fields too large" which is pretty + # much the only situation where we can get here + raise RemoteProtocolError( + "Receive buffer too long", error_status_hint=431 + ) + if self._receive_buffer_closed: + # We're still trying to complete some event, but that's + # never going to happen because no more data is coming + raise RemoteProtocolError("peer unexpectedly closed connection") + return event + except BaseException as exc: + self._process_error(self.their_role) + if isinstance(exc, LocalProtocolError): + exc._reraise_as_remote_protocol_error() + else: + raise + + def send(self, event: Event) -> Optional[bytes]: + """Convert a high-level event into bytes that can be sent to the peer, + while updating our internal state machine. + + Args: + event: The :ref:`event <events>` to send. + + Returns: + If ``type(event) is ConnectionClosed``, then returns + ``None``. Otherwise, returns a :term:`bytes-like object`. + + Raises: + LocalProtocolError: + Sending this event at this time would violate our + understanding of the HTTP/1.1 protocol. + + If this method raises any exception then it also sets + :attr:`Connection.our_state` to :data:`ERROR` -- see + :ref:`error-handling` for discussion. + + """ + data_list = self.send_with_data_passthrough(event) + if data_list is None: + return None + else: + return b"".join(data_list) + + def send_with_data_passthrough(self, event: Event) -> Optional[List[bytes]]: + """Identical to :meth:`send`, except that in situations where + :meth:`send` returns a single :term:`bytes-like object`, this instead + returns a list of them -- and when sending a :class:`Data` event, this + list is guaranteed to contain the exact object you passed in as + :attr:`Data.data`. See :ref:`sendfile` for discussion. + + """ + if self.our_state is ERROR: + raise LocalProtocolError("Can't send data when our state is ERROR") + try: + if type(event) is Response: + event = self._clean_up_response_headers_for_sending(event) + # We want to call _process_event before calling the writer, + # because if someone tries to do something invalid then this will + # give a sensible error message, while our writers all just assume + # they will only receive valid events. But, _process_event might + # change self._writer. So we have to do a little dance: + writer = self._writer + self._process_event(self.our_role, event) + if type(event) is ConnectionClosed: + return None + else: + # In any situation where writer is None, process_event should + # have raised ProtocolError + assert writer is not None + data_list: List[bytes] = [] + writer(event, data_list.append) + return data_list + except: + self._process_error(self.our_role) + raise + + def send_failed(self) -> None: + """Notify the state machine that we failed to send the data it gave + us. + + This causes :attr:`Connection.our_state` to immediately become + :data:`ERROR` -- see :ref:`error-handling` for discussion. + + """ + self._process_error(self.our_role) + + # When sending a Response, we take responsibility for a few things: + # + # - Sometimes you MUST set Connection: close. We take care of those + # times. (You can also set it yourself if you want, and if you do then + # we'll respect that and close the connection at the right time. But you + # don't have to worry about that unless you want to.) + # + # - The user has to set Content-Length if they want it. Otherwise, for + # responses that have bodies (e.g. not HEAD), then we will automatically + # select the right mechanism for streaming a body of unknown length, + # which depends on depending on the peer's HTTP version. + # + # This function's *only* responsibility is making sure headers are set up + # right -- everything downstream just looks at the headers. There are no + # side channels. + def _clean_up_response_headers_for_sending(self, response: Response) -> Response: + assert type(response) is Response + + headers = response.headers + need_close = False + + # HEAD requests need some special handling: they always act like they + # have Content-Length: 0, and that's how _body_framing treats + # them. But their headers are supposed to match what we would send if + # the request was a GET. (Technically there is one deviation allowed: + # we're allowed to leave out the framing headers -- see + # https://tools.ietf.org/html/rfc7231#section-4.3.2 . But it's just as + # easy to get them right.) + method_for_choosing_headers = cast(bytes, self._request_method) + if method_for_choosing_headers == b"HEAD": + method_for_choosing_headers = b"GET" + framing_type, _ = _body_framing(method_for_choosing_headers, response) + if framing_type in ("chunked", "http/1.0"): + # This response has a body of unknown length. + # If our peer is HTTP/1.1, we use Transfer-Encoding: chunked + # If our peer is HTTP/1.0, we use no framing headers, and close the + # connection afterwards. + # + # Make sure to clear Content-Length (in principle user could have + # set both and then we ignored Content-Length b/c + # Transfer-Encoding overwrote it -- this would be naughty of them, + # but the HTTP spec says that if our peer does this then we have + # to fix it instead of erroring out, so we'll accord the user the + # same respect). + headers = set_comma_header(headers, b"content-length", []) + if self.their_http_version is None or self.their_http_version < b"1.1": + # Either we never got a valid request and are sending back an + # error (their_http_version is None), so we assume the worst; + # or else we did get a valid HTTP/1.0 request, so we know that + # they don't understand chunked encoding. + headers = set_comma_header(headers, b"transfer-encoding", []) + # This is actually redundant ATM, since currently we + # unconditionally disable keep-alive when talking to HTTP/1.0 + # peers. But let's be defensive just in case we add + # Connection: keep-alive support later: + if self._request_method != b"HEAD": + need_close = True + else: + headers = set_comma_header(headers, b"transfer-encoding", [b"chunked"]) + + if not self._cstate.keep_alive or need_close: + # Make sure Connection: close is set + connection = set(get_comma_header(headers, b"connection")) + connection.discard(b"keep-alive") + connection.add(b"close") + headers = set_comma_header(headers, b"connection", sorted(connection)) + + return Response( + headers=headers, + status_code=response.status_code, + http_version=response.http_version, + reason=response.reason, + ) |