Загрузить файлы в «venv/Lib/site-packages/h11»

venv/Lib/site-packages/h11/_readers.py

@@ -0,0 +1,250 @@
+# Code to read HTTP data
+#
+# Strategy: each reader is a callable which takes a ReceiveBuffer object, and
+# either:
+# 1) consumes some of it and returns an Event
+# 2) raises a LocalProtocolError (for consistency -- e.g. we call validate()
+#    and it might raise a LocalProtocolError, so simpler just to always use
+#    this)
+# 3) returns None, meaning "I need more data"
+#
+# If they have a .read_eof attribute, then this will be called if an EOF is
+# received -- but this is optional. Either way, the actual ConnectionClosed
+# event will be generated afterwards.
+#
+# READERS is a dict describing how to pick a reader. It maps states to either:
+# - a reader
+# - or, for body readers, a dict of per-framing reader factories
+
+import re
+from typing import Any, Callable, Dict, Iterable, NoReturn, Optional, Tuple, Type, Union
+
+from ._abnf import chunk_header, header_field, request_line, status_line
+from ._events import Data, EndOfMessage, InformationalResponse, Request, Response
+from ._receivebuffer import ReceiveBuffer
+from ._state import (
+    CLIENT,
+    CLOSED,
+    DONE,
+    IDLE,
+    MUST_CLOSE,
+    SEND_BODY,
+    SEND_RESPONSE,
+    SERVER,
+)
+from ._util import LocalProtocolError, RemoteProtocolError, Sentinel, validate
+
+__all__ = ["READERS"]
+
+header_field_re = re.compile(header_field.encode("ascii"))
+obs_fold_re = re.compile(rb"[ \t]+")
+
+
+def _obsolete_line_fold(lines: Iterable[bytes]) -> Iterable[bytes]:
+    it = iter(lines)
+    last: Optional[bytes] = None
+    for line in it:
+        match = obs_fold_re.match(line)
+        if match:
+            if last is None:
+                raise LocalProtocolError("continuation line at start of headers")
+            if not isinstance(last, bytearray):
+                # Cast to a mutable type, avoiding copy on append to ensure O(n) time
+                last = bytearray(last)
+            last += b" "
+            last += line[match.end() :]
+        else:
+            if last is not None:
+                yield last
+            last = line
+    if last is not None:
+        yield last
+
+
+def _decode_header_lines(
+    lines: Iterable[bytes],
+) -> Iterable[Tuple[bytes, bytes]]:
+    for line in _obsolete_line_fold(lines):
+        matches = validate(header_field_re, line, "illegal header line: {!r}", line)
+        yield (matches["field_name"], matches["field_value"])
+
+
+request_line_re = re.compile(request_line.encode("ascii"))
+
+
+def maybe_read_from_IDLE_client(buf: ReceiveBuffer) -> Optional[Request]:
+    lines = buf.maybe_extract_lines()
+    if lines is None:
+        if buf.is_next_line_obviously_invalid_request_line():
+            raise LocalProtocolError("illegal request line")
+        return None
+    if not lines:
+        raise LocalProtocolError("no request line received")
+    matches = validate(
+        request_line_re, lines[0], "illegal request line: {!r}", lines[0]
+    )
+    return Request(
+        headers=list(_decode_header_lines(lines[1:])), _parsed=True, **matches
+    )
+
+
+status_line_re = re.compile(status_line.encode("ascii"))
+
+
+def maybe_read_from_SEND_RESPONSE_server(
+    buf: ReceiveBuffer,
+) -> Union[InformationalResponse, Response, None]:
+    lines = buf.maybe_extract_lines()
+    if lines is None:
+        if buf.is_next_line_obviously_invalid_request_line():
+            raise LocalProtocolError("illegal request line")
+        return None
+    if not lines:
+        raise LocalProtocolError("no response line received")
+    matches = validate(status_line_re, lines[0], "illegal status line: {!r}", lines[0])
+    http_version = (
+        b"1.1" if matches["http_version"] is None else matches["http_version"]
+    )
+    reason = b"" if matches["reason"] is None else matches["reason"]
+    status_code = int(matches["status_code"])
+    class_: Union[Type[InformationalResponse], Type[Response]] = (
+        InformationalResponse if status_code < 200 else Response
+    )
+    return class_(
+        headers=list(_decode_header_lines(lines[1:])),
+        _parsed=True,
+        status_code=status_code,
+        reason=reason,
+        http_version=http_version,
+    )
+
+
+class ContentLengthReader:
+    def __init__(self, length: int) -> None:
+        self._length = length
+        self._remaining = length
+
+    def __call__(self, buf: ReceiveBuffer) -> Union[Data, EndOfMessage, None]:
+        if self._remaining == 0:
+            return EndOfMessage()
+        data = buf.maybe_extract_at_most(self._remaining)
+        if data is None:
+            return None
+        self._remaining -= len(data)
+        return Data(data=data)
+
+    def read_eof(self) -> NoReturn:
+        raise RemoteProtocolError(
+            "peer closed connection without sending complete message body "
+            "(received {} bytes, expected {})".format(
+                self._length - self._remaining, self._length
+            )
+        )
+
+
+chunk_header_re = re.compile(chunk_header.encode("ascii"))
+
+
+class ChunkedReader:
+    def __init__(self) -> None:
+        self._bytes_in_chunk = 0
+        # After reading a chunk, we have to throw away the trailing \r\n.
+        # This tracks the bytes that we need to match and throw away.
+        self._bytes_to_discard = b""
+        self._reading_trailer = False
+
+    def __call__(self, buf: ReceiveBuffer) -> Union[Data, EndOfMessage, None]:
+        if self._reading_trailer:
+            lines = buf.maybe_extract_lines()
+            if lines is None:
+                return None
+            return EndOfMessage(headers=list(_decode_header_lines(lines)))
+        if self._bytes_to_discard:
+            data = buf.maybe_extract_at_most(len(self._bytes_to_discard))
+            if data is None:
+                return None
+            if data != self._bytes_to_discard[: len(data)]:
+                raise LocalProtocolError(
+                    f"malformed chunk footer: {data!r} (expected {self._bytes_to_discard!r})"
+                )
+            self._bytes_to_discard = self._bytes_to_discard[len(data) :]
+            if self._bytes_to_discard:
+                return None
+            # else, fall through and read some more
+        assert self._bytes_to_discard == b""
+        if self._bytes_in_chunk == 0:
+            # We need to refill our chunk count
+            chunk_header = buf.maybe_extract_next_line()
+            if chunk_header is None:
+                return None
+            matches = validate(
+                chunk_header_re,
+                chunk_header,
+                "illegal chunk header: {!r}",
+                chunk_header,
+            )
+            # XX FIXME: we discard chunk extensions. Does anyone care?
+            self._bytes_in_chunk = int(matches["chunk_size"], base=16)
+            if self._bytes_in_chunk == 0:
+                self._reading_trailer = True
+                return self(buf)
+            chunk_start = True
+        else:
+            chunk_start = False
+        assert self._bytes_in_chunk > 0
+        data = buf.maybe_extract_at_most(self._bytes_in_chunk)
+        if data is None:
+            return None
+        self._bytes_in_chunk -= len(data)
+        if self._bytes_in_chunk == 0:
+            self._bytes_to_discard = b"\r\n"
+            chunk_end = True
+        else:
+            chunk_end = False
+        return Data(data=data, chunk_start=chunk_start, chunk_end=chunk_end)
+
+    def read_eof(self) -> NoReturn:
+        raise RemoteProtocolError(
+            "peer closed connection without sending complete message body "
+            "(incomplete chunked read)"
+        )
+
+
+class Http10Reader:
+    def __call__(self, buf: ReceiveBuffer) -> Optional[Data]:
+        data = buf.maybe_extract_at_most(999999999)
+        if data is None:
+            return None
+        return Data(data=data)
+
+    def read_eof(self) -> EndOfMessage:
+        return EndOfMessage()
+
+
+def expect_nothing(buf: ReceiveBuffer) -> None:
+    if buf:
+        raise LocalProtocolError("Got data when expecting EOF")
+    return None
+
+
+ReadersType = Dict[
+    Union[Type[Sentinel], Tuple[Type[Sentinel], Type[Sentinel]]],
+    Union[Callable[..., Any], Dict[str, Callable[..., Any]]],
+]
+
+READERS: ReadersType = {
+    (CLIENT, IDLE): maybe_read_from_IDLE_client,
+    (SERVER, IDLE): maybe_read_from_SEND_RESPONSE_server,
+    (SERVER, SEND_RESPONSE): maybe_read_from_SEND_RESPONSE_server,
+    (CLIENT, DONE): expect_nothing,
+    (CLIENT, MUST_CLOSE): expect_nothing,
+    (CLIENT, CLOSED): expect_nothing,
+    (SERVER, DONE): expect_nothing,
+    (SERVER, MUST_CLOSE): expect_nothing,
+    (SERVER, CLOSED): expect_nothing,
+    SEND_BODY: {
+        "chunked": ChunkedReader,
+        "content-length": ContentLengthReader,
+        "http/1.0": Http10Reader,
+    },
+}

venv/Lib/site-packages/h11/_receivebuffer.py

@@ -0,0 +1,153 @@
+import re
+import sys
+from typing import List, Optional, Union
+
+__all__ = ["ReceiveBuffer"]
+
+
+# Operations we want to support:
+# - find next \r\n or \r\n\r\n (\n or \n\n are also acceptable),
+#   or wait until there is one
+# - read at-most-N bytes
+# Goals:
+# - on average, do this fast
+# - worst case, do this in O(n) where n is the number of bytes processed
+# Plan:
+# - store bytearray, offset, how far we've searched for a separator token
+# - use the how-far-we've-searched data to avoid rescanning
+# - while doing a stream of uninterrupted processing, advance offset instead
+#   of constantly copying
+# WARNING:
+# - I haven't benchmarked or profiled any of this yet.
+#
+# Note that starting in Python 3.4, deleting the initial n bytes from a
+# bytearray is amortized O(n), thanks to some excellent work by Antoine
+# Martin:
+#
+#     https://bugs.python.org/issue19087
+#
+# This means that if we only supported 3.4+, we could get rid of the code here
+# involving self._start and self.compress, because it's doing exactly the same
+# thing that bytearray now does internally.
+#
+# BUT unfortunately, we still support 2.7, and reading short segments out of a
+# long buffer MUST be O(bytes read) to avoid DoS issues, so we can't actually
+# delete this code. Yet:
+#
+#     https://pythonclock.org/
+#
+# (Two things to double-check first though: make sure PyPy also has the
+# optimization, and benchmark to make sure it's a win, since we do have a
+# slightly clever thing where we delay calling compress() until we've
+# processed a whole event, which could in theory be slightly more efficient
+# than the internal bytearray support.)
+blank_line_regex = re.compile(b"\n\r?\n", re.MULTILINE)
+
+
+class ReceiveBuffer:
+    def __init__(self) -> None:
+        self._data = bytearray()
+        self._next_line_search = 0
+        self._multiple_lines_search = 0
+
+    def __iadd__(self, byteslike: Union[bytes, bytearray]) -> "ReceiveBuffer":
+        self._data += byteslike
+        return self
+
+    def __bool__(self) -> bool:
+        return bool(len(self))
+
+    def __len__(self) -> int:
+        return len(self._data)
+
+    # for @property unprocessed_data
+    def __bytes__(self) -> bytes:
+        return bytes(self._data)
+
+    def _extract(self, count: int) -> bytearray:
+        # extracting an initial slice of the data buffer and return it
+        out = self._data[:count]
+        del self._data[:count]
+
+        self._next_line_search = 0
+        self._multiple_lines_search = 0
+
+        return out
+
+    def maybe_extract_at_most(self, count: int) -> Optional[bytearray]:
+        """
+        Extract a fixed number of bytes from the buffer.
+        """
+        out = self._data[:count]
+        if not out:
+            return None
+
+        return self._extract(count)
+
+    def maybe_extract_next_line(self) -> Optional[bytearray]:
+        """
+        Extract the first line, if it is completed in the buffer.
+        """
+        # Only search in buffer space that we've not already looked at.
+        search_start_index = max(0, self._next_line_search - 1)
+        partial_idx = self._data.find(b"\r\n", search_start_index)
+
+        if partial_idx == -1:
+            self._next_line_search = len(self._data)
+            return None
+
+        # + 2 is to compensate len(b"\r\n")
+        idx = partial_idx + 2
+
+        return self._extract(idx)
+
+    def maybe_extract_lines(self) -> Optional[List[bytearray]]:
+        """
+        Extract everything up to the first blank line, and return a list of lines.
+        """
+        # Handle the case where we have an immediate empty line.
+        if self._data[:1] == b"\n":
+            self._extract(1)
+            return []
+
+        if self._data[:2] == b"\r\n":
+            self._extract(2)
+            return []
+
+        # Only search in buffer space that we've not already looked at.
+        match = blank_line_regex.search(self._data, self._multiple_lines_search)
+        if match is None:
+            self._multiple_lines_search = max(0, len(self._data) - 2)
+            return None
+
+        # Truncate the buffer and return it.
+        idx = match.span(0)[-1]
+        out = self._extract(idx)
+        lines = out.split(b"\n")
+
+        for line in lines:
+            if line.endswith(b"\r"):
+                del line[-1]
+
+        assert lines[-2] == lines[-1] == b""
+
+        del lines[-2:]
+
+        return lines
+
+    # In theory we should wait until `\r\n` before starting to validate
+    # incoming data. However it's interesting to detect (very) invalid data
+    # early given they might not even contain `\r\n` at all (hence only
+    # timeout will get rid of them).
+    # This is not a 100% effective detection but more of a cheap sanity check
+    # allowing for early abort in some useful cases.
+    # This is especially interesting when peer is messing up with HTTPS and
+    # sent us a TLS stream where we were expecting plain HTTP given all
+    # versions of TLS so far start handshake with a 0x16 message type code.
+    def is_next_line_obviously_invalid_request_line(self) -> bool:
+        try:
+            # HTTP header line must not contain non-printable characters
+            # and should not start with a space
+            return self._data[0] < 0x21
+        except IndexError:
+            return False

venv/Lib/site-packages/h11/_state.py

@@ -0,0 +1,365 @@
+################################################################
+# The core state machine
+################################################################
+#
+# Rule 1: everything that affects the state machine and state transitions must
+# live here in this file. As much as possible goes into the table-based
+# representation, but for the bits that don't quite fit, the actual code and
+# state must nonetheless live here.
+#
+# Rule 2: this file does not know about what role we're playing; it only knows
+# about HTTP request/response cycles in the abstract. This ensures that we
+# don't cheat and apply different rules to local and remote parties.
+#
+#
+# Theory of operation
+# ===================
+#
+# Possibly the simplest way to think about this is that we actually have 5
+# different state machines here. Yes, 5. These are:
+#
+# 1) The client state, with its complicated automaton (see the docs)
+# 2) The server state, with its complicated automaton (see the docs)
+# 3) The keep-alive state, with possible states {True, False}
+# 4) The SWITCH_CONNECT state, with possible states {False, True}
+# 5) The SWITCH_UPGRADE state, with possible states {False, True}
+#
+# For (3)-(5), the first state listed is the initial state.
+#
+# (1)-(3) are stored explicitly in member variables. The last
+# two are stored implicitly in the pending_switch_proposals set as:
+#   (state of 4) == (_SWITCH_CONNECT in pending_switch_proposals)
+#   (state of 5) == (_SWITCH_UPGRADE in pending_switch_proposals)
+#
+# And each of these machines has two different kinds of transitions:
+#
+# a) Event-triggered
+# b) State-triggered
+#
+# Event triggered is the obvious thing that you'd think it is: some event
+# happens, and if it's the right event at the right time then a transition
+# happens. But there are somewhat complicated rules for which machines can
+# "see" which events. (As a rule of thumb, if a machine "sees" an event, this
+# means two things: the event can affect the machine, and if the machine is
+# not in a state where it expects that event then it's an error.) These rules
+# are:
+#
+# 1) The client machine sees all h11.events objects emitted by the client.
+#
+# 2) The server machine sees all h11.events objects emitted by the server.
+#
+#    It also sees the client's Request event.
+#
+#    And sometimes, server events are annotated with a _SWITCH_* event. For
+#    example, we can have a (Response, _SWITCH_CONNECT) event, which is
+#    different from a regular Response event.
+#
+# 3) The keep-alive machine sees the process_keep_alive_disabled() event
+#    (which is derived from Request/Response events), and this event
+#    transitions it from True -> False, or from False -> False. There's no way
+#    to transition back.
+#
+# 4&5) The _SWITCH_* machines transition from False->True when we get a
+#    Request that proposes the relevant type of switch (via
+#    process_client_switch_proposals), and they go from True->False when we
+#    get a Response that has no _SWITCH_* annotation.
+#
+# So that's event-triggered transitions.
+#
+# State-triggered transitions are less standard. What they do here is couple
+# the machines together. The way this works is, when certain *joint*
+# configurations of states are achieved, then we automatically transition to a
+# new *joint* state. So, for example, if we're ever in a joint state with
+#
+#   client: DONE
+#   keep-alive: False
+#
+# then the client state immediately transitions to:
+#
+#   client: MUST_CLOSE
+#
+# This is fundamentally different from an event-based transition, because it
+# doesn't matter how we arrived at the {client: DONE, keep-alive: False} state
+# -- maybe the client transitioned SEND_BODY -> DONE, or keep-alive
+# transitioned True -> False. Either way, once this precondition is satisfied,
+# this transition is immediately triggered.
+#
+# What if two conflicting state-based transitions get enabled at the same
+# time?  In practice there's only one case where this arises (client DONE ->
+# MIGHT_SWITCH_PROTOCOL versus DONE -> MUST_CLOSE), and we resolve it by
+# explicitly prioritizing the DONE -> MIGHT_SWITCH_PROTOCOL transition.
+#
+# Implementation
+# --------------
+#
+# The event-triggered transitions for the server and client machines are all
+# stored explicitly in a table. Ditto for the state-triggered transitions that
+# involve just the server and client state.
+#
+# The transitions for the other machines, and the state-triggered transitions
+# that involve the other machines, are written out as explicit Python code.
+#
+# It'd be nice if there were some cleaner way to do all this. This isn't
+# *too* terrible, but I feel like it could probably be better.
+#
+# WARNING
+# -------
+#
+# The script that generates the state machine diagrams for the docs knows how
+# to read out the EVENT_TRIGGERED_TRANSITIONS and STATE_TRIGGERED_TRANSITIONS
+# tables. But it can't automatically read the transitions that are written
+# directly in Python code. So if you touch those, you need to also update the
+# script to keep it in sync!
+from typing import cast, Dict, Optional, Set, Tuple, Type, Union
+
+from ._events import *
+from ._util import LocalProtocolError, Sentinel
+
+# Everything in __all__ gets re-exported as part of the h11 public API.
+__all__ = [
+    "CLIENT",
+    "SERVER",
+    "IDLE",
+    "SEND_RESPONSE",
+    "SEND_BODY",
+    "DONE",
+    "MUST_CLOSE",
+    "CLOSED",
+    "MIGHT_SWITCH_PROTOCOL",
+    "SWITCHED_PROTOCOL",
+    "ERROR",
+]
+
+
+class CLIENT(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class SERVER(Sentinel, metaclass=Sentinel):
+    pass
+
+
+# States
+class IDLE(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class SEND_RESPONSE(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class SEND_BODY(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class DONE(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class MUST_CLOSE(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class CLOSED(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class ERROR(Sentinel, metaclass=Sentinel):
+    pass
+
+
+# Switch types
+class MIGHT_SWITCH_PROTOCOL(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class SWITCHED_PROTOCOL(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class _SWITCH_UPGRADE(Sentinel, metaclass=Sentinel):
+    pass
+
+
+class _SWITCH_CONNECT(Sentinel, metaclass=Sentinel):
+    pass
+
+
+EventTransitionType = Dict[
+    Type[Sentinel],
+    Dict[
+        Type[Sentinel],
+        Dict[Union[Type[Event], Tuple[Type[Event], Type[Sentinel]]], Type[Sentinel]],
+    ],
+]
+
+EVENT_TRIGGERED_TRANSITIONS: EventTransitionType = {
+    CLIENT: {
+        IDLE: {Request: SEND_BODY, ConnectionClosed: CLOSED},
+        SEND_BODY: {Data: SEND_BODY, EndOfMessage: DONE},
+        DONE: {ConnectionClosed: CLOSED},
+        MUST_CLOSE: {ConnectionClosed: CLOSED},
+        CLOSED: {ConnectionClosed: CLOSED},
+        MIGHT_SWITCH_PROTOCOL: {},
+        SWITCHED_PROTOCOL: {},
+        ERROR: {},
+    },
+    SERVER: {
+        IDLE: {
+            ConnectionClosed: CLOSED,
+            Response: SEND_BODY,
+            # Special case: server sees client Request events, in this form
+            (Request, CLIENT): SEND_RESPONSE,
+        },
+        SEND_RESPONSE: {
+            InformationalResponse: SEND_RESPONSE,
+            Response: SEND_BODY,
+            (InformationalResponse, _SWITCH_UPGRADE): SWITCHED_PROTOCOL,
+            (Response, _SWITCH_CONNECT): SWITCHED_PROTOCOL,
+        },
+        SEND_BODY: {Data: SEND_BODY, EndOfMessage: DONE},
+        DONE: {ConnectionClosed: CLOSED},
+        MUST_CLOSE: {ConnectionClosed: CLOSED},
+        CLOSED: {ConnectionClosed: CLOSED},
+        SWITCHED_PROTOCOL: {},
+        ERROR: {},
+    },
+}
+
+StateTransitionType = Dict[
+    Tuple[Type[Sentinel], Type[Sentinel]], Dict[Type[Sentinel], Type[Sentinel]]
+]
+
+# NB: there are also some special-case state-triggered transitions hard-coded
+# into _fire_state_triggered_transitions below.
+STATE_TRIGGERED_TRANSITIONS: StateTransitionType = {
+    # (Client state, Server state) -> new states
+    # Protocol negotiation
+    (MIGHT_SWITCH_PROTOCOL, SWITCHED_PROTOCOL): {CLIENT: SWITCHED_PROTOCOL},
+    # Socket shutdown
+    (CLOSED, DONE): {SERVER: MUST_CLOSE},
+    (CLOSED, IDLE): {SERVER: MUST_CLOSE},
+    (ERROR, DONE): {SERVER: MUST_CLOSE},
+    (DONE, CLOSED): {CLIENT: MUST_CLOSE},
+    (IDLE, CLOSED): {CLIENT: MUST_CLOSE},
+    (DONE, ERROR): {CLIENT: MUST_CLOSE},
+}
+
+
+class ConnectionState:
+    def __init__(self) -> None:
+        # Extra bits of state that don't quite fit into the state model.
+
+        # If this is False then it enables the automatic DONE -> MUST_CLOSE
+        # transition. Don't set this directly; call .keep_alive_disabled()
+        self.keep_alive = True
+
+        # This is a subset of {UPGRADE, CONNECT}, containing the proposals
+        # made by the client for switching protocols.
+        self.pending_switch_proposals: Set[Type[Sentinel]] = set()
+
+        self.states: Dict[Type[Sentinel], Type[Sentinel]] = {CLIENT: IDLE, SERVER: IDLE}
+
+    def process_error(self, role: Type[Sentinel]) -> None:
+        self.states[role] = ERROR
+        self._fire_state_triggered_transitions()
+
+    def process_keep_alive_disabled(self) -> None:
+        self.keep_alive = False
+        self._fire_state_triggered_transitions()
+
+    def process_client_switch_proposal(self, switch_event: Type[Sentinel]) -> None:
+        self.pending_switch_proposals.add(switch_event)
+        self._fire_state_triggered_transitions()
+
+    def process_event(
+        self,
+        role: Type[Sentinel],
+        event_type: Type[Event],
+        server_switch_event: Optional[Type[Sentinel]] = None,
+    ) -> None:
+        _event_type: Union[Type[Event], Tuple[Type[Event], Type[Sentinel]]] = event_type
+        if server_switch_event is not None:
+            assert role is SERVER
+            if server_switch_event not in self.pending_switch_proposals:
+                raise LocalProtocolError(
+                    "Received server _SWITCH_UPGRADE event without a pending proposal"
+                )
+            _event_type = (event_type, server_switch_event)
+        if server_switch_event is None and _event_type is Response:
+            self.pending_switch_proposals = set()
+        self._fire_event_triggered_transitions(role, _event_type)
+        # Special case: the server state does get to see Request
+        # events.
+        if _event_type is Request:
+            assert role is CLIENT
+            self._fire_event_triggered_transitions(SERVER, (Request, CLIENT))
+        self._fire_state_triggered_transitions()
+
+    def _fire_event_triggered_transitions(
+        self,
+        role: Type[Sentinel],
+        event_type: Union[Type[Event], Tuple[Type[Event], Type[Sentinel]]],
+    ) -> None:
+        state = self.states[role]
+        try:
+            new_state = EVENT_TRIGGERED_TRANSITIONS[role][state][event_type]
+        except KeyError:
+            event_type = cast(Type[Event], event_type)
+            raise LocalProtocolError(
+                "can't handle event type {} when role={} and state={}".format(
+                    event_type.__name__, role, self.states[role]
+                )
+            ) from None
+        self.states[role] = new_state
+
+    def _fire_state_triggered_transitions(self) -> None:
+        # We apply these rules repeatedly until converging on a fixed point
+        while True:
+            start_states = dict(self.states)
+
+            # It could happen that both these special-case transitions are
+            # enabled at the same time:
+            #
+            #    DONE -> MIGHT_SWITCH_PROTOCOL
+            #    DONE -> MUST_CLOSE
+            #
+            # For example, this will always be true of a HTTP/1.0 client
+            # requesting CONNECT.  If this happens, the protocol switch takes
+            # priority. From there the client will either go to
+            # SWITCHED_PROTOCOL, in which case it's none of our business when
+            # they close the connection, or else the server will deny the
+            # request, in which case the client will go back to DONE and then
+            # from there to MUST_CLOSE.
+            if self.pending_switch_proposals:
+                if self.states[CLIENT] is DONE:
+                    self.states[CLIENT] = MIGHT_SWITCH_PROTOCOL
+
+            if not self.pending_switch_proposals:
+                if self.states[CLIENT] is MIGHT_SWITCH_PROTOCOL:
+                    self.states[CLIENT] = DONE
+
+            if not self.keep_alive:
+                for role in (CLIENT, SERVER):
+                    if self.states[role] is DONE:
+                        self.states[role] = MUST_CLOSE
+
+            # Tabular state-triggered transitions
+            joint_state = (self.states[CLIENT], self.states[SERVER])
+            changes = STATE_TRIGGERED_TRANSITIONS.get(joint_state, {})
+            self.states.update(changes)
+
+            if self.states == start_states:
+                # Fixed point reached
+                return
+
+    def start_next_cycle(self) -> None:
+        if self.states != {CLIENT: DONE, SERVER: DONE}:
+            raise LocalProtocolError(
+                f"not in a reusable state. self.states={self.states}"
+            )
+        # Can't reach DONE/DONE with any of these active, but still, let's be
+        # sure.
+        assert self.keep_alive
+        assert not self.pending_switch_proposals
+        self.states = {CLIENT: IDLE, SERVER: IDLE}

venv/Lib/site-packages/h11/_util.py

@@ -0,0 +1,135 @@
+from typing import Any, Dict, NoReturn, Pattern, Tuple, Type, TypeVar, Union
+
+__all__ = [
+    "ProtocolError",
+    "LocalProtocolError",
+    "RemoteProtocolError",
+    "validate",
+    "bytesify",
+]
+
+
+class ProtocolError(Exception):
+    """Exception indicating a violation of the HTTP/1.1 protocol.
+
+    This as an abstract base class, with two concrete base classes:
+    :exc:`LocalProtocolError`, which indicates that you tried to do something
+    that HTTP/1.1 says is illegal, and :exc:`RemoteProtocolError`, which
+    indicates that the remote peer tried to do something that HTTP/1.1 says is
+    illegal. See :ref:`error-handling` for details.
+
+    In addition to the normal :exc:`Exception` features, it has one attribute:
+
+    .. attribute:: error_status_hint
+
+       This gives a suggestion as to what status code a server might use if
+       this error occurred as part of a request.
+
+       For a :exc:`RemoteProtocolError`, this is useful as a suggestion for
+       how you might want to respond to a misbehaving peer, if you're
+       implementing a server.
+
+       For a :exc:`LocalProtocolError`, this can be taken as a suggestion for
+       how your peer might have responded to *you* if h11 had allowed you to
+       continue.
+
+       The default is 400 Bad Request, a generic catch-all for protocol
+       violations.
+
+    """
+
+    def __init__(self, msg: str, error_status_hint: int = 400) -> None:
+        if type(self) is ProtocolError:
+            raise TypeError("tried to directly instantiate ProtocolError")
+        Exception.__init__(self, msg)
+        self.error_status_hint = error_status_hint
+
+
+# Strategy: there are a number of public APIs where a LocalProtocolError can
+# be raised (send(), all the different event constructors, ...), and only one
+# public API where RemoteProtocolError can be raised
+# (receive_data()). Therefore we always raise LocalProtocolError internally,
+# and then receive_data will translate this into a RemoteProtocolError.
+#
+# Internally:
+#   LocalProtocolError is the generic "ProtocolError".
+# Externally:
+#   LocalProtocolError is for local errors and RemoteProtocolError is for
+#   remote errors.
+class LocalProtocolError(ProtocolError):
+    def _reraise_as_remote_protocol_error(self) -> NoReturn:
+        # After catching a LocalProtocolError, use this method to re-raise it
+        # as a RemoteProtocolError. This method must be called from inside an
+        # except: block.
+        #
+        # An easy way to get an equivalent RemoteProtocolError is just to
+        # modify 'self' in place.
+        self.__class__ = RemoteProtocolError  # type: ignore
+        # But the re-raising is somewhat non-trivial -- you might think that
+        # now that we've modified the in-flight exception object, that just
+        # doing 'raise' to re-raise it would be enough. But it turns out that
+        # this doesn't work, because Python tracks the exception type
+        # (exc_info[0]) separately from the exception object (exc_info[1]),
+        # and we only modified the latter. So we really do need to re-raise
+        # the new type explicitly.
+        # On py3, the traceback is part of the exception object, so our
+        # in-place modification preserved it and we can just re-raise:
+        raise self
+
+
+class RemoteProtocolError(ProtocolError):
+    pass
+
+
+def validate(
+    regex: Pattern[bytes], data: bytes, msg: str = "malformed data", *format_args: Any
+) -> Dict[str, bytes]:
+    match = regex.fullmatch(data)
+    if not match:
+        if format_args:
+            msg = msg.format(*format_args)
+        raise LocalProtocolError(msg)
+    return match.groupdict()
+
+
+# Sentinel values
+#
+# - Inherit identity-based comparison and hashing from object
+# - Have a nice repr
+# - Have a *bonus property*: type(sentinel) is sentinel
+#
+# The bonus property is useful if you want to take the return value from
+# next_event() and do some sort of dispatch based on type(event).
+
+_T_Sentinel = TypeVar("_T_Sentinel", bound="Sentinel")
+
+
+class Sentinel(type):
+    def __new__(
+        cls: Type[_T_Sentinel],
+        name: str,
+        bases: Tuple[type, ...],
+        namespace: Dict[str, Any],
+        **kwds: Any
+    ) -> _T_Sentinel:
+        assert bases == (Sentinel,)
+        v = super().__new__(cls, name, bases, namespace, **kwds)
+        v.__class__ = v  # type: ignore
+        return v
+
+    def __repr__(self) -> str:
+        return self.__name__
+
+
+# Used for methods, request targets, HTTP versions, header names, and header
+# values. Accepts ascii-strings, or bytes/bytearray/memoryview/..., and always
+# returns bytes.
+def bytesify(s: Union[bytes, bytearray, memoryview, int, str]) -> bytes:
+    # Fast-path:
+    if type(s) is bytes:
+        return s
+    if isinstance(s, str):
+        s = s.encode("ascii")
+    if isinstance(s, int):
+        raise TypeError("expected bytes-like object, not int")
+    return bytes(s)

venv/Lib/site-packages/h11/_version.py

@@ -0,0 +1,16 @@
+# This file must be kept very simple, because it is consumed from several
+# places -- it is imported by h11/__init__.py, execfile'd by setup.py, etc.
+
+# We use a simple scheme:
+#   1.0.0 -> 1.0.0+dev -> 1.1.0 -> 1.1.0+dev
+# where the +dev versions are never released into the wild, they're just what
+# we stick into the VCS in between releases.
+#
+# This is compatible with PEP 440:
+#   http://legacy.python.org/dev/peps/pep-0440/
+# via the use of the "local suffix" "+dev", which is disallowed on index
+# servers and causes 1.0.0+dev to sort after plain 1.0.0, which is what we
+# want. (Contrast with the special suffix 1.0.0.dev, which sorts *before*
+# 1.0.0.)
+
+__version__ = "0.16.0"