# Source code for tornado.httputil

    #
    # Copyright 2009 Facebook
    #
    # Licensed under the Apache License, Version 2.0 (the "License"); you may
    # not use this file except in compliance with the License. You may obtain
    # a copy of the License at
    #
    #     http://www.apache.org/licenses/LICENSE-2.0
    #
    # Unless required by applicable law or agreed to in writing, software
    # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    # License for the specific language governing permissions and limitations
    # under the License.

    """HTTP utility code shared by clients and servers.

    This module also defines the `HTTPServerRequest` class which is exposed
    via `tornado.web.RequestHandler.request`.
    """

    import calendar
    import collections.abc
    import copy
    import datetime
    import email.utils
    from functools import lru_cache
    from http.client import responses
    import http.cookies
    import re
    from ssl import SSLError
    import time
    import unicodedata
    from urllib.parse import urlencode, urlparse, urlunparse, parse_qsl

    from tornado.escape import native_str, parse_qs_bytes, utf8
    from tornado.util import ObjectDict, unicode_type

    # responses is unused in this file, but we re-export it to other files.
    # Reference it so pyflakes doesn't complain.
    responses

    import typing
    from typing import (
        Tuple,
        Iterable,
        List,
        Mapping,
        Iterator,
        Dict,
        Union,
        Optional,
        Awaitable,
        Generator,
        AnyStr,
    )

    if typing.TYPE_CHECKING:
        from typing import Deque  # noqa: F401
        from asyncio import Future  # noqa: F401
        import unittest  # noqa: F401

    # To be used with str.strip() and related methods.
    HTTP_WHITESPACE = " \t"

    class _ABNF:
        """Class that holds a subset of ABNF rules from RFC 9110 and friends.

        Class attributes are re.Pattern objects, with the same name as in the RFC
        (with hyphens changed to underscores). Currently contains only the subset
        we use (which is why this class is not public). Unfortunately the fields
        cannot be alphabetized as they are in the RFCs because of dependencies.
        """

        # RFC 5234 (ABNF)
        VCHAR = re.compile(r"[\x21-\x7E]")

        # RFC 9110 (HTTP Semantics)
        obs_text = re.compile(r"[\x80-\xFF]")
        tchar = re.compile(r"[!#$%&'*+\-.^_`|~0-9A-Za-z]")
        token = re.compile(rf"{tchar.pattern}+")
        field_name = token

        # RFC 9112 (HTTP/1.1)
        HTTP_version = re.compile(r"HTTP/[0-9]\.[0-9]")
        reason_phrase = re.compile(rf"(?:[\t ]|{VCHAR.pattern}|{obs_text.pattern})+")
        status_code = re.compile(r"[0-9]{3}")
        status_line = re.compile(
            rf"({HTTP_version.pattern}) ({status_code.pattern}) ({reason_phrase.pattern})?"
        )

    @lru_cache(1000)
    def _normalize_header(name: str) -> str:
        """Map a header name to Http-Header-Case.

        >>> _normalize_header("coNtent-TYPE")
        'Content-Type'
        """
        return "-".join([w.capitalize() for w in name.split("-")])

    class HTTPHeaders(collections.abc.MutableMapping):
        """A dictionary that maintains ``Http-Header-Case`` for all keys.

        Supports multiple values per key via a pair of new methods,
        `add()` and `get_list()`.  The regular dictionary interface
        returns a single value per key, with multiple values joined by a
        comma.

        >>> h = HTTPHeaders({"content-type": "text/html"})
        >>> list(h.keys())
        ['Content-Type']
        >>> h["Content-Type"]
        'text/html'

        >>> h.add("Set-Cookie", "A=B")
        >>> h.add("Set-Cookie", "C=D")
        >>> h["set-cookie"]
        'A=B,C=D'
        >>> h.get_list("set-cookie")
        ['A=B', 'C=D']

        >>> for (k,v) in sorted(h.get_all()):
        ...    print('%s: %s' % (k,v))
        ...
        Content-Type: text/html
        Set-Cookie: A=B
        Set-Cookie: C=D
        """

        @typing.overload
        def __init__(self, __arg: Mapping[str, List[str]]) -> None:
            pass

        @typing.overload  # noqa: F811
        def __init__(self, __arg: Mapping[str, str]) -> None:
            pass

        @typing.overload  # noqa: F811
        def __init__(self, *args: Tuple[str, str]) -> None:
            pass

        @typing.overload  # noqa: F811
        def __init__(self, **kwargs: str) -> None:
            pass

        def __init__(self, *args: typing.Any, **kwargs: str) -> None:  # noqa: F811
            # Formally, HTTP headers are a mapping from a field name to a "combined field value",
            # which may be constructed from multiple field lines by joining them with commas.
            # In practice, however, some headers (notably Set-Cookie) do not follow this convention,
            # so we maintain a mapping from field name to a list of field lines in self._as_list.
            # self._combined_cache is a cache of the combined field values derived from self._as_list
            # on demand (and cleared whenever the list is modified).
            self._as_list: dict[str, list[str]] = {}
            self._combined_cache: dict[str, str] = {}
            self._last_key = None  # type: Optional[str]
            if len(args) == 1 and len(kwargs) == 0 and isinstance(args[0], HTTPHeaders):
                # Copy constructor
                for k, v in args[0].get_all():
                    self.add(k, v)
            else:
                # Dict-style initialization
                self.update(*args, **kwargs)

        # new public methods

        def add(self, name: str, value: str) -> None:
            """Adds a new value for the given key."""
            if not _ABNF.token.fullmatch(name):
                raise HTTPInputError("Invalid header name %r" % name)
            norm_name = _normalize_header(name)
            self._last_key = norm_name
            if norm_name in self:
                self._combined_cache.pop(norm_name, None)
                self._as_list[norm_name].append(value)
            else:
                self[norm_name] = value

        def get_list(self, name: str) -> List[str]:
            """Returns all values for the given header as a list."""
            norm_name = _normalize_header(name)
            return self._as_list.get(norm_name, [])

        def get_all(self) -> Iterable[Tuple[str, str]]:
            """Returns an iterable of all (name, value) pairs.

            If a header has multiple values, multiple pairs will be
            returned with the same name.
            """
            for name, values in self._as_list.items():
                for value in values:
                    yield (name, value)

        def parse_line(self, line: str) -> None:
            """Updates the dictionary with a single header line.

            >>> h = HTTPHeaders()
            >>> h.parse_line("Content-Type: text/html")
            >>> h.get('content-type')
            'text/html'
            """
            if line[0].isspace():
                # continuation of a multi-line header
                if self._last_key is None:
                    raise HTTPInputError("first header line cannot start with whitespace")
                new_part = " " + line.lstrip(HTTP_WHITESPACE)
                self._as_list[self._last_key][-1] += new_part
                self._combined_cache.pop(self._last_key, None)
            else:
                try:
                    name, value = line.split(":", 1)
                except ValueError:
                    raise HTTPInputError("no colon in header line")
                self.add(name, value.strip(HTTP_WHITESPACE))

        @classmethod
        def parse(cls, headers: str) -> "HTTPHeaders":
            """Returns a dictionary from HTTP header text.

            >>> h = HTTPHeaders.parse("Content-Type: text/html\\r\\nContent-Length: 42\\r\\n")
            >>> sorted(h.items())
            [('Content-Length', '42'), ('Content-Type', 'text/html')]

            .. versionchanged:: 5.1

               Raises `HTTPInputError` on malformed headers instead of a
               mix of `KeyError`, and `ValueError`.

            """
            h = cls()
            # RFC 7230 section 3.5: a recipient MAY recognize a single LF as a line
            # terminator and ignore any preceding CR.
            for line in headers.split("\n"):
                if line.endswith("\r"):
                    line = line[:-1]
                if line:
                    h.parse_line(line)
            return h

        # MutableMapping abstract method implementations.

        def __setitem__(self, name: str, value: str) -> None:
            norm_name = _normalize_header(name)
            self._combined_cache[norm_name] = value
            self._as_list[norm_name] = [value]

        def __contains__(self, name: object) -> bool:
            # This is an important optimization to avoid the expensive concatenation
            # in __getitem__ when it's not needed.
            if not isinstance(name, str):
                return False
            norm_name = _normalize_header(name)
            return norm_name in self._as_list

        def __getitem__(self, name: str) -> str:
            header = _normalize_header(name)
            if header not in self._combined_cache:
                self._combined_cache[header] = ",".join(self._as_list[header])
            return self._combined_cache[header]

        def __delitem__(self, name: str) -> None:
            norm_name = _normalize_header(name)
            del self._combined_cache[norm_name]
            del self._as_list[norm_name]

        def __len__(self) -> int:
            return len(self._as_list)

        def __iter__(self) -> Iterator[typing.Any]:
            return iter(self._as_list)

        def copy(self) -> "HTTPHeaders":
            # defined in dict but not in MutableMapping.
            return HTTPHeaders(self)

        # Use our overridden copy method for the copy.copy module.
        # This makes shallow copies one level deeper, but preserves
        # the appearance that HTTPHeaders is a single container.
        __copy__ = copy

        def __str__(self) -> str:
            lines = []
            for name, value in self.get_all():
                lines.append("%s: %s\n" % (name, value))
            return "".join(lines)

        __unicode__ = __str__

    class HTTPServerRequest(object):
        """A single HTTP request.

        All attributes are type `str` unless otherwise noted.

        .. attribute:: method

           HTTP request method, e.g. "GET" or "POST"

        .. attribute:: uri

           The requested uri.

        .. attribute:: path

           The path portion of `uri`

        .. attribute:: query

           The query portion of `uri`

        .. attribute:: version

           HTTP version specified in request, e.g. "HTTP/1.1"

        .. attribute:: headers

           `.HTTPHeaders` dictionary-like object for request headers.  Acts like
           a case-insensitive dictionary with additional methods for repeated
           headers.

        .. attribute:: body

           Request body, if present, as a byte string.

        .. attribute:: remote_ip

           Client's IP address as a string.  If ``HTTPServer.xheaders`` is set,
           will pass along the real IP address provided by a load balancer
           in the ``X-Real-Ip`` or ``X-Forwarded-For`` header.

        .. versionchanged:: 3.1
           The list format of ``X-Forwarded-For`` is now supported.

        .. attribute:: protocol

           The protocol used, either "http" or "https".  If ``HTTPServer.xheaders``
           is set, will pass along the protocol used by a load balancer if
           reported via an ``X-Scheme`` header.

        .. attribute:: host

           The requested hostname, usually taken from the ``Host`` header.

        .. attribute:: arguments

           GET/POST arguments are available in the arguments property, which
           maps arguments names to lists of values (to support multiple values
           for individual names). Names are of type `str`, while arguments
           are byte strings.  Note that this is different from
           `.RequestHandler.get_argument`, which returns argument values as
           unicode strings.

        .. attribute:: query_arguments

           Same format as ``arguments``, but contains only arguments extracted
           from the query string.

           .. versionadded:: 3.2

        .. attribute:: body_arguments

           Same format as ``arguments``, but contains only arguments extracted
           from the request body.

           .. versionadded:: 3.2

        .. attribute:: files

           File uploads are available in the files property, which maps file
           names to lists of `.HTTPFile`.

        .. attribute:: connection

           An HTTP request is attached to a single HTTP connection, which can
           be accessed through the "connection" attribute. Since connections
           are typically kept open in HTTP/1.1, multiple requests can be handled
           sequentially on a single connection.

        .. versionchanged:: 4.0
           Moved from ``tornado.httpserver.HTTPRequest``.
        """

        path = None  # type: str
        query = None  # type: str

        # HACK: Used for stream_request_body
        _body_future = None  # type: Future[None]

        def __init__(
            self,
            method: Optional[str] = None,
            uri: Optional[str] = None,
            version: str = "HTTP/1.0",
            headers: Optional[HTTPHeaders] = None,
            body: Optional[bytes] = None,
            host: Optional[str] = None,
            files: Optional[Dict[str, List["HTTPFile"]]] = None,
            connection: Optional["HTTPConnection"] = None,
            start_line: Optional["RequestStartLine"] = None,
            server_connection: Optional[object] = None,
        ) -> None:
            if start_line is not None:
                method, uri, version = start_line
            self.method = method
            self.uri = uri
            self.version = version
            self.headers = headers or HTTPHeaders()
            self.body = body or b""

            # set remote IP and protocol
            context = getattr(connection, "context", None)
            self.remote_ip = getattr(context, "remote_ip", None)
            self.protocol = getattr(context, "protocol", "http")

            self.host = host or self.headers.get("Host") or "127.0.0.1"
            self.host_name = split_host_and_port(self.host.lower())[0]
            self.files = files or {}
            self.connection = connection
            self.server_connection = server_connection
            self._start_time = time.time()
            self._finish_time = None

            if uri is not None:
                self.path, sep, self.query = uri.partition("?")
            self.arguments = parse_qs_bytes(self.query, keep_blank_values=True)
            self.query_arguments = copy.deepcopy(self.arguments)
            self.body_arguments = {}  # type: Dict[str, List[bytes]]

        @property
        def cookies(self) -> Dict[str, http.cookies.Morsel]:
            """A dictionary of ``http.cookies.Morsel`` objects."""
            if not hasattr(self, "_cookies"):
                self._cookies = (
                    http.cookies.SimpleCookie()
                )  # type: http.cookies.SimpleCookie
                if "Cookie" in self.headers:
                    try:
                        parsed = parse_cookie(self.headers["Cookie"])
                    except Exception:
                        pass
                    else:
                        for k, v in parsed.items():
                            try:
                                self._cookies[k] = v
                            except Exception:
                                # SimpleCookie imposes some restrictions on keys;
                                # parse_cookie does not. Discard any cookies
                                # with disallowed keys.
                                pass
            return self._cookies

        def full_url(self) -> str:
            """Reconstructs the full URL for this request."""
            return self.protocol + "://" + self.host + self.uri  # type: ignore[operator]

        def request_time(self) -> float:
            """Returns the amount of time it took for this request to execute."""
            if self._finish_time is None:
                return time.time() - self._start_time
            else:
                return self._finish_time - self._start_time

        def get_ssl_certificate(
            self, binary_form: bool = False
        ) -> Union[None, Dict, bytes]:
            """Returns the client's SSL certificate, if any.

            To use client certificates, the HTTPServer's
            `ssl.SSLContext.verify_mode` field must be set, e.g.::

                ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
                ssl_ctx.load_cert_chain("foo.crt", "foo.key")
                ssl_ctx.load_verify_locations("cacerts.pem")
                ssl_ctx.verify_mode = ssl.CERT_REQUIRED
                server = HTTPServer(app, ssl_options=ssl_ctx)

            By default, the return value is a dictionary (or None, if no
            client certificate is present).  If ``binary_form`` is true, a
            DER-encoded form of the certificate is returned instead.  See
            SSLSocket.getpeercert() in the standard library for more
            details.
            http://docs.python.org/library/ssl.html#sslsocket-objects
            """
            try:
                if self.connection is None:
                    return None
                # TODO: add a method to HTTPConnection for this so it can work with HTTP/2
                return self.connection.stream.socket.getpeercert(  # type: ignore
                    binary_form=binary_form
                )
            except SSLError:
                return None

        def _parse_body(self) -> None:
            parse_body_arguments(
                self.headers.get("Content-Type", ""),
                self.body,
                self.body_arguments,
                self.files,
                self.headers,
            )

            for k, v in self.body_arguments.items():
                self.arguments.setdefault(k, []).extend(v)

        def __repr__(self) -> str:
            attrs = ("protocol", "host", "method", "uri", "version", "remote_ip")
            args = ", ".join(["%s=%r" % (n, getattr(self, n)) for n in attrs])
            return "%s(%s)" % (self.__class__.__name__, args)

    class HTTPInputError(Exception):
        """Exception class for malformed HTTP requests or responses
        from remote sources.

        .. versionadded:: 4.0
        """

        pass

    class HTTPOutputError(Exception):
        """Exception class for errors in HTTP output.

        .. versionadded:: 4.0
        """

        pass

    class HTTPServerConnectionDelegate(object):
        """Implement this interface to handle requests from `.HTTPServer`.

        .. versionadded:: 4.0
        """

        def start_request(
            self, server_conn: object, request_conn: "HTTPConnection"
        ) -> "HTTPMessageDelegate":
            """This method is called by the server when a new request has started.

            :arg server_conn: is an opaque object representing the long-lived
                (e.g. tcp-level) connection.
            :arg request_conn: is a `.HTTPConnection` object for a single
                request/response exchange.

            This method should return a `.HTTPMessageDelegate`.
            """
            raise NotImplementedError()

        def on_close(self, server_conn: object) -> None:
            """This method is called when a connection has been closed.

            :arg server_conn: is a server connection that has previously been
                passed to ``start_request``.
            """
            pass

    class HTTPMessageDelegate(object):
        """Implement this interface to handle an HTTP request or response.

        .. versionadded:: 4.0
        """

        # TODO: genericize this class to avoid exposing the Union.

        def headers_received(
            self,
            start_line: Union["RequestStartLine", "ResponseStartLine"],
            headers: HTTPHeaders,
        ) -> Optional[Awaitable[None]]:
            """Called when the HTTP headers have been received and parsed.

            :arg start_line: a `.RequestStartLine` or `.ResponseStartLine`
                depending on whether this is a client or server message.
            :arg headers: a `.HTTPHeaders` instance.

            Some `.HTTPConnection` methods can only be called during
            ``headers_received``.

            May return a `.Future`; if it does the body will not be read
            until it is done.
            """
            pass

        def data_received(self, chunk: bytes) -> Optional[Awaitable[None]]:
            """Called when a chunk of data has been received.

            May return a `.Future` for flow control.
            """
            pass

        def finish(self) -> None:
            """Called after the last chunk of data has been received."""
            pass

        def on_connection_close(self) -> None:
            """Called if the connection is closed without finishing the request.

            If ``headers_received`` is called, either ``finish`` or
            ``on_connection_close`` will be called, but not both.
            """
            pass

    class HTTPConnection(object):
        """Applications use this interface to write their responses.

        .. versionadded:: 4.0
        """

        def write_headers(
            self,
            start_line: Union["RequestStartLine", "ResponseStartLine"],
            headers: HTTPHeaders,
            chunk: Optional[bytes] = None,
        ) -> "Future[None]":
            """Write an HTTP header block.

            :arg start_line: a `.RequestStartLine` or `.ResponseStartLine`.
            :arg headers: a `.HTTPHeaders` instance.
            :arg chunk: the first (optional) chunk of data.  This is an optimization
                so that small responses can be written in the same call as their
                headers.

            The ``version`` field of ``start_line`` is ignored.

            Returns a future for flow control.

            .. versionchanged:: 6.0

               The ``callback`` argument was removed.
            """
            raise NotImplementedError()

        def write(self, chunk: bytes) -> "Future[None]":
            """Writes a chunk of body data.

            Returns a future for flow control.

            .. versionchanged:: 6.0

               The ``callback`` argument was removed.
            """
            raise NotImplementedError()

        def finish(self) -> None:
            """Indicates that the last body data has been written."""
            raise NotImplementedError()

    def url_concat(
        url: str,
        args: Union[
            None, Dict[str, str], List[Tuple[str, str]], Tuple[Tuple[str, str], ...]
        ],
    ) -> str:
        """Concatenate url and arguments regardless of whether
        url has existing query parameters.

        ``args`` may be either a dictionary or a list of key-value pairs
        (the latter allows for multiple values with the same key.

        >>> url_concat("http://example.com/foo", dict(c="d"))
        'http://example.com/foo?c=d'
        >>> url_concat("http://example.com/foo?a=b", dict(c="d"))
        'http://example.com/foo?a=b&c=d'
        >>> url_concat("http://example.com/foo?a=b", [("c", "d"), ("c", "d2")])
        'http://example.com/foo?a=b&c=d&c=d2'
        """
        if args is None:
            return url
        parsed_url = urlparse(url)
        if isinstance(args, dict):
            parsed_query = parse_qsl(parsed_url.query, keep_blank_values=True)
            parsed_query.extend(args.items())
        elif isinstance(args, list) or isinstance(args, tuple):
            parsed_query = parse_qsl(parsed_url.query, keep_blank_values=True)
            parsed_query.extend(args)
        else:
            err = "'args' parameter should be dict, list or tuple. Not {0}".format(
                type(args)
            )
            raise TypeError(err)
        final_query = urlencode(parsed_query)
        url = urlunparse(
            (
                parsed_url[0],
                parsed_url[1],
                parsed_url[2],
                parsed_url[3],
                final_query,
                parsed_url[5],
            )
        )
        return url

    class HTTPFile(ObjectDict):
        """Represents a file uploaded via a form.

        For backwards compatibility, its instance attributes are also
        accessible as dictionary keys.

        * ``filename``
        * ``body``
        * ``content_type``
        """

        filename: str
        body: bytes
        content_type: str

    def _parse_request_range(
        range_header: str,
    ) -> Optional[Tuple[Optional[int], Optional[int]]]:
        """Parses a Range header.

        Returns either ``None`` or tuple ``(start, end)``.
        Note that while the HTTP headers use inclusive byte positions,
        this method returns indexes suitable for use in slices.

        >>> start, end = _parse_request_range("bytes=1-2")
        >>> start, end
        (1, 3)
        >>> [0, 1, 2, 3, 4][start:end]
        [1, 2]
        >>> _parse_request_range("bytes=6-")
        (6, None)
        >>> _parse_request_range("bytes=-6")
        (-6, None)
        >>> _parse_request_range("bytes=-0")
        (None, 0)
        >>> _parse_request_range("bytes=")
        (None, None)
        >>> _parse_request_range("foo=42")
        >>> _parse_request_range("bytes=1-2,6-10")

        Note: only supports one range (ex, ``bytes=1-2,6-10`` is not allowed).

        See [0] for the details of the range header.

        [0]: http://greenbytes.de/tech/webdav/draft-ietf-httpbis-p5-range-latest.html#byte.ranges
        """
        unit, _, value = range_header.partition("=")
        unit, value = unit.strip(), value.strip()
        if unit != "bytes":
            return None
        start_b, _, end_b = value.partition("-")
        try:
            start = _int_or_none(start_b)
            end = _int_or_none(end_b)
        except ValueError:
            return None
        if end is not None:
            if start is None:
                if end != 0:
                    start = -end
                    end = None
            else:
                end += 1
        return (start, end)

    def _get_content_range(start: Optional[int], end: Optional[int], total: int) -> str:
        """Returns a suitable Content-Range header:

        >>> print(_get_content_range(None, 1, 4))
        bytes 0-0/4
        >>> print(_get_content_range(1, 3, 4))
        bytes 1-2/4
        >>> print(_get_content_range(None, None, 4))
        bytes 0-3/4
        """
        start = start or 0
        end = (end or total) - 1
        return "bytes %s-%s/%s" % (start, end, total)

    def _int_or_none(val: str) -> Optional[int]:
        val = val.strip()
        if val == "":
            return None
        return int(val)

    def parse_body_arguments(
        content_type: str,
        body: bytes,
        arguments: Dict[str, List[bytes]],
        files: Dict[str, List[HTTPFile]],
        headers: Optional[HTTPHeaders] = None,
    ) -> None:
        """Parses a form request body.

        Supports ``application/x-www-form-urlencoded`` and
        ``multipart/form-data``.  The ``content_type`` parameter should be
        a string and ``body`` should be a byte string.  The ``arguments``
        and ``files`` parameters are dictionaries that will be updated
        with the parsed contents.
        """
        if content_type.startswith("application/x-www-form-urlencoded"):
            if headers and "Content-Encoding" in headers:
                raise HTTPInputError(
                    "Unsupported Content-Encoding: %s" % headers["Content-Encoding"]
                )
            try:
                # real charset decoding will happen in RequestHandler.decode_argument()
                uri_arguments = parse_qs_bytes(body, keep_blank_values=True)
            except Exception as e:
                raise HTTPInputError("Invalid x-www-form-urlencoded body: %s" % e) from e
            for name, values in uri_arguments.items():
                if values:
                    arguments.setdefault(name, []).extend(values)
        elif content_type.startswith("multipart/form-data"):
            if headers and "Content-Encoding" in headers:
                raise HTTPInputError(
                    "Unsupported Content-Encoding: %s" % headers["Content-Encoding"]
                )
            try:
                fields = content_type.split(";")
                for field in fields:
                    k, sep, v = field.strip().partition("=")
                    if k == "boundary" and v:
                        parse_multipart_form_data(utf8(v), body, arguments, files)
                        break
                else:
                    raise HTTPInputError("multipart boundary not found")
            except Exception as e:
                raise HTTPInputError("Invalid multipart/form-data: %s" % e) from e

    def parse_multipart_form_data(
        boundary: bytes,
        data: bytes,
        arguments: Dict[str, List[bytes]],
        files: Dict[str, List[HTTPFile]],
    ) -> None:
        """Parses a ``multipart/form-data`` body.

        The ``boundary`` and ``data`` parameters are both byte strings.
        The dictionaries given in the arguments and files parameters
        will be updated with the contents of the body.

        .. versionchanged:: 5.1

           Now recognizes non-ASCII filenames in RFC 2231/5987
           (``filename*=``) format.
        """
        # The standard allows for the boundary to be quoted in the header,
        # although it's rare (it happens at least for google app engine
        # xmpp).  I think we're also supposed to handle backslash-escapes
        # here but I'll save that until we see a client that uses them
        # in the wild.
        if boundary.startswith(b'"') and boundary.endswith(b'"'):
            boundary = boundary[1:-1]
        final_boundary_index = data.rfind(b"--" + boundary + b"--")
        if final_boundary_index == -1:
            raise HTTPInputError("Invalid multipart/form-data: no final boundary found")
        parts = data[:final_boundary_index].split(b"--" + boundary + b"\r\n")
        for part in parts:
            if not part:
                continue
            eoh = part.find(b"\r\n\r\n")
            if eoh == -1:
                raise HTTPInputError("multipart/form-data missing headers")
            headers = HTTPHeaders.parse(part[:eoh].decode("utf-8"))
            disp_header = headers.get("Content-Disposition", "")
            disposition, disp_params = _parse_header(disp_header)
            if disposition != "form-data" or not part.endswith(b"\r\n"):
                raise HTTPInputError("Invalid multipart/form-data")
            value = part[eoh + 4 : -2]
            if not disp_params.get("name"):
                raise HTTPInputError("multipart/form-data missing name")
            name = disp_params["name"]
            if disp_params.get("filename"):
                ctype = headers.get("Content-Type", "application/unknown")
                files.setdefault(name, []).append(
                    HTTPFile(
                        filename=disp_params["filename"], body=value, content_type=ctype
                    )
                )
            else:
                arguments.setdefault(name, []).append(value)

    def format_timestamp(
        ts: Union[int, float, tuple, time.struct_time, datetime.datetime],
    ) -> str:
        """Formats a timestamp in the format used by HTTP.

        The argument may be a numeric timestamp as returned by `time.time`,
        a time tuple as returned by `time.gmtime`, or a `datetime.datetime`
        object. Naive `datetime.datetime` objects are assumed to represent
        UTC; aware objects are converted to UTC before formatting.

        >>> format_timestamp(1359312200)
        'Sun, 27 Jan 2013 18:43:20 GMT'
        """
        if isinstance(ts, (int, float)):
            time_num = ts
        elif isinstance(ts, (tuple, time.struct_time)):
            time_num = calendar.timegm(ts)
        elif isinstance(ts, datetime.datetime):
            time_num = calendar.timegm(ts.utctimetuple())
        else:
            raise TypeError("unknown timestamp type: %r" % ts)
        return email.utils.formatdate(time_num, usegmt=True)

    RequestStartLine = collections.namedtuple(
        "RequestStartLine", ["method", "path", "version"]
    )

    def parse_request_start_line(line: str) -> RequestStartLine:
        """Returns a (method, path, version) tuple for an HTTP 1.x request line.

        The response is a `collections.namedtuple`.

        >>> parse_request_start_line("GET /foo HTTP/1.1")
        RequestStartLine(method='GET', path='/foo', version='HTTP/1.1')
        """
        try:
            method, path, version = line.split(" ")
        except ValueError:
            # https://tools.ietf.org/html/rfc7230#section-3.1.1
            # invalid request-line SHOULD respond with a 400 (Bad Request)
            raise HTTPInputError("Malformed HTTP request line")
        if not _ABNF.HTTP_version.fullmatch(version):
            raise HTTPInputError(
                "Malformed HTTP version in HTTP Request-Line: %r" % version
            )
        if not version.startswith("HTTP/1"):
            # HTTP/2 and above doesn't use parse_request_start_line.
            # This could be folded into the regex but we don't want to deviate
            # from the ABNF in the RFCs.
            raise HTTPInputError("Unexpected HTTP version %r" % version)
        return RequestStartLine(method, path, version)

    ResponseStartLine = collections.namedtuple(
        "ResponseStartLine", ["version", "code", "reason"]
    )

    def parse_response_start_line(line: str) -> ResponseStartLine:
        """Returns a (version, code, reason) tuple for an HTTP 1.x response line.

        The response is a `collections.namedtuple`.

        >>> parse_response_start_line("HTTP/1.1 200 OK")
        ResponseStartLine(version='HTTP/1.1', code=200, reason='OK')
        """
        match = _ABNF.status_line.fullmatch(line)
        if not match:
            raise HTTPInputError("Error parsing response start line")
        r = ResponseStartLine(match.group(1), int(match.group(2)), match.group(3))
        if not r.version.startswith("HTTP/1"):
            # HTTP/2 and above doesn't use parse_response_start_line.
            raise HTTPInputError("Unexpected HTTP version %r" % r.version)
        return r

    # _parseparam and _parse_header are copied and modified from python2.7's cgi.py
    # The original 2.7 version of this code did not correctly support some
    # combinations of semicolons and double quotes.
    # It has also been modified to support valueless parameters as seen in
    # websocket extension negotiations, and to support non-ascii values in
    # RFC 2231/5987 format.
    #
    # _parseparam has been further modified with the logic from
    # https://github.com/python/cpython/pull/136072/files
    # to avoid quadratic behavior when parsing semicolons in quoted strings.
    #
    # TODO: See if we can switch to email.message.Message for this functionality.
    # This is the suggested replacement for the cgi.py module now that cgi has
    # been removed from recent versions of Python.  We need to verify that
    # the email module is consistent with our existing behavior (and all relevant
    # RFCs for multipart/form-data) before making this change.

    def _parseparam(s: str) -> Generator[str, None, None]:
        start = 0
        while s.find(";", start) == start:
            start += 1
            end = s.find(";", start)
            ind, diff = start, 0
            while end > 0:
                diff += s.count('"', ind, end) - s.count('\\"', ind, end)
                if diff % 2 == 0:
                    break
                end, ind = ind, s.find(";", end + 1)
            if end < 0:
                end = len(s)
            f = s[start:end]
            yield f.strip()
            start = end

    def _parse_header(line: str) -> Tuple[str, Dict[str, str]]:
        r"""Parse a Content-type like header.

        Return the main content-type and a dictionary of options.

        >>> d = "form-data; foo=\"b\\\\a\\\"r\"; file*=utf-8''T%C3%A4st"
        >>> ct, d = _parse_header(d)
        >>> ct
        'form-data'
        >>> d['file'] == r'T\u00e4st'.encode('ascii').decode('unicode_escape')
        True
        >>> d['foo']
        'b\\a"r'
        """
        parts = _parseparam(";" + line)
        key = next(parts)
        # decode_params treats first argument special, but we already stripped key
        params = [("Dummy", "value")]
        for p in parts:
            i = p.find("=")
            if i >= 0:
                name = p[:i].strip().lower()
                value = p[i + 1 :].strip()
                params.append((name, native_str(value)))
        decoded_params = email.utils.decode_params(params)
        decoded_params.pop(0)  # get rid of the dummy again
        pdict = {}
        for name, decoded_value in decoded_params:
            value = email.utils.collapse_rfc2231_value(decoded_value)
            if len(value) >= 2 and value[0] == '"' and value[-1] == '"':
                value = value[1:-1]
            pdict[name] = value
        return key, pdict

    def _encode_header(key: str, pdict: Dict[str, str]) -> str:
        """Inverse of _parse_header.

        >>> _encode_header('permessage-deflate',
        ...     {'client_max_window_bits': 15, 'client_no_context_takeover': None})
        'permessage-deflate; client_max_window_bits=15; client_no_context_takeover'
        """
        if not pdict:
            return key
        out = [key]
        # Sort the parameters just to make it easy to test.
        for k, v in sorted(pdict.items()):
            if v is None:
                out.append(k)
            else:
                # TODO: quote if necessary.
                out.append("%s=%s" % (k, v))
        return "; ".join(out)

    def encode_username_password(
        username: Union[str, bytes], password: Union[str, bytes]
    ) -> bytes:
        """Encodes a username/password pair in the format used by HTTP auth.

        The return value is a byte string in the form ``username:password``.

        .. versionadded:: 5.1
        """
        if isinstance(username, unicode_type):
            username = unicodedata.normalize("NFC", username)
        if isinstance(password, unicode_type):
            password = unicodedata.normalize("NFC", password)
        return utf8(username) + b":" + utf8(password)

    def doctests():
        # type: () -> unittest.TestSuite
        import doctest

        return doctest.DocTestSuite()

    _netloc_re = re.compile(r"^(.+):(\d+)$")

    def split_host_and_port(netloc: str) -> Tuple[str, Optional[int]]:
        """Returns ``(host, port)`` tuple from ``netloc``.

        Returned ``port`` will be ``None`` if not present.

        .. versionadded:: 4.1
        """
        match = _netloc_re.match(netloc)
        if match:
            host = match.group(1)
            port = int(match.group(2))  # type: Optional[int]
        else:
            host = netloc
            port = None
        return (host, port)

    def qs_to_qsl(qs: Dict[str, List[AnyStr]]) -> Iterable[Tuple[str, AnyStr]]:
        """Generator converting a result of ``parse_qs`` back to name-value pairs.

        .. versionadded:: 5.0
        """
        for k, vs in qs.items():
            for v in vs:
                yield (k, v)

    _unquote_sub = re.compile(r"\\(?:([0-3][0-7][0-7])|(.))").sub

    def _unquote_replace(m: re.Match) -> str:
        if m[1]:
            return chr(int(m[1], 8))
        else:
            return m[2]

    def _unquote_cookie(s: str) -> str:
        """Handle double quotes and escaping in cookie values.

        This method is copied verbatim from the Python 3.13 standard
        library (http.cookies._unquote) so we don't have to depend on
        non-public interfaces.
        """
        # If there aren't any doublequotes,
        # then there can't be any special characters.  See RFC 2109.
        if s is None or len(s) < 2:
            return s
        if s[0] != '"' or s[-1] != '"':
            return s

        # We have to assume that we must decode this string.
        # Down to work.

        # Remove the "s
        s = s[1:-1]

        # Check for special sequences.  Examples:
        #    \012 --> \n
        #    \"   --> "
        #
        return _unquote_sub(_unquote_replace, s)

    def parse_cookie(cookie: str) -> Dict[str, str]:
        """Parse a ``Cookie`` HTTP header into a dict of name/value pairs.

        This function attempts to mimic browser cookie parsing behavior;
        it specifically does not follow any of the cookie-related RFCs
        (because browsers don't either).

        The algorithm used is identical to that used by Django version 1.9.10.

        .. versionadded:: 4.4.2
        """
        cookiedict = {}
        for chunk in cookie.split(str(";")):
            if str("=") in chunk:
                key, val = chunk.split(str("="), 1)
            else:
                # Assume an empty name per
                # https://bugzilla.mozilla.org/show_bug.cgi?id=169091
                key, val = str(""), chunk
            key, val = key.strip(), val.strip()
            if key or val:
                # unquote using Python's algorithm.
                cookiedict[key] = _unquote_cookie(val)
        return cookiedict