http_parser.py

import abc
import asyncio
import collections
import re
import string
import zlib
from contextlib import suppress
from enum import IntEnum
from typing import Any, Generic, List, Optional, Tuple, Type, TypeVar, Union

from multidict import CIMultiDict, CIMultiDictProxy, istr
from yarl import URL

from . import hdrs
from .base_protocol import BaseProtocol
from .helpers import NO_EXTENSIONS, BaseTimerContext
from .http_exceptions import (
    BadStatusLine,
    ContentEncodingError,
    ContentLengthError,
    InvalidHeader,
    LineTooLong,
    TransferEncodingError,
)
from .http_writer import HttpVersion, HttpVersion10
from .log import internal_logger
from .streams import EMPTY_PAYLOAD, StreamReader
from .typedefs import RawHeaders

try:
    import brotli

    HAS_BROTLI = True
except ImportError:  # pragma: no cover
    HAS_BROTLI = False


__all__ = (
    "HeadersParser",
    "HttpParser",
    "HttpRequestParser",
    "HttpResponseParser",
    "RawRequestMessage",
    "RawResponseMessage",
)

ASCIISET = set(string.printable)

# See https://tools.ietf.org/html/rfc7230#section-3.1.1
# and https://tools.ietf.org/html/rfc7230#appendix-B
#
#     method = token
#     tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /
#             "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA
#     token = 1*tchar
METHRE = re.compile(r"[!#$%&'*+\-.^_`|~0-9A-Za-z]+")
VERSRE = re.compile(r"HTTP/(\d+).(\d+)")
HDRRE = re.compile(rb"[\x00-\x1F\x7F()<>@,;:\[\]={} \t\\\\\"]")

RawRequestMessage = collections.namedtuple(
    "RawRequestMessage",
    [
        "method",
        "path",
        "version",
        "headers",
        "raw_headers",
        "should_close",
        "compression",
        "upgrade",
        "chunked",
        "url",
    ],
)

RawResponseMessage = collections.namedtuple(
    "RawResponseMessage",
    [
        "version",
        "code",
        "reason",
        "headers",
        "raw_headers",
        "should_close",
        "compression",
        "upgrade",
        "chunked",
    ],
)


_MsgT = TypeVar("_MsgT", RawRequestMessage, RawResponseMessage)


class ParseState(IntEnum):

    PARSE_NONE = 0
    PARSE_LENGTH = 1
    PARSE_CHUNKED = 2
    PARSE_UNTIL_EOF = 3


class ChunkState(IntEnum):
    PARSE_CHUNKED_SIZE = 0
    PARSE_CHUNKED_CHUNK = 1
    PARSE_CHUNKED_CHUNK_EOF = 2
    PARSE_MAYBE_TRAILERS = 3
    PARSE_TRAILERS = 4


class HeadersParser:
    def __init__(
        self,
        max_line_size: int = 8190,
        max_headers: int = 32768,
        max_field_size: int = 8190,
    ) -> None:
        self.max_line_size = max_line_size
        self.max_headers = max_headers
        self.max_field_size = max_field_size

    def parse_headers(
        self, lines: List[bytes]
    ) -> Tuple["CIMultiDictProxy[str]", RawHeaders]:
        headers = CIMultiDict()  # type: CIMultiDict[str]
        raw_headers = []

        lines_idx = 1
        line = lines[1]
        line_count = len(lines)

        while line:
            # Parse initial header name : value pair.
            try:
                bname, bvalue = line.split(b":", 1)
            except ValueError:
                raise InvalidHeader(line) from None

            bname = bname.strip(b" \t")
            bvalue = bvalue.lstrip()
            if HDRRE.search(bname):
                raise InvalidHeader(bname)
            if len(bname) > self.max_field_size:
                raise LineTooLong(
                    "request header name {}".format(
                        bname.decode("utf8", "xmlcharrefreplace")
                    ),
                    str(self.max_field_size),
                    str(len(bname)),
                )

            header_length = len(bvalue)

            # next line
            lines_idx += 1
            line = lines[lines_idx]

            # consume continuation lines
            continuation = line and line[0] in (32, 9)  # (' ', '\t')

            if continuation:
                bvalue_lst = [bvalue]
                while continuation:
                    header_length += len(line)
                    if header_length > self.max_field_size:
                        raise LineTooLong(
                            "request header field {}".format(
                                bname.decode("utf8", "xmlcharrefreplace")
                            ),
                            str(self.max_field_size),
                            str(header_length),
                        )
                    bvalue_lst.append(line)

                    # next line
                    lines_idx += 1
                    if lines_idx < line_count:
                        line = lines[lines_idx]
                        if line:
                            continuation = line[0] in (32, 9)  # (' ', '\t')
                    else:
                        line = b""
                        break
                bvalue = b"".join(bvalue_lst)
            else:
                if header_length > self.max_field_size:
                    raise LineTooLong(
                        "request header field {}".format(
                            bname.decode("utf8", "xmlcharrefreplace")
                        ),
                        str(self.max_field_size),
                        str(header_length),
                    )

            bvalue = bvalue.strip()
            name = bname.decode("utf-8", "surrogateescape")
            value = bvalue.decode("utf-8", "surrogateescape")

            headers.add(name, value)
            raw_headers.append((bname, bvalue))

        return (CIMultiDictProxy(headers), tuple(raw_headers))


class HttpParser(abc.ABC, Generic[_MsgT]):
    def __init__(
        self,
        protocol: BaseProtocol,
        loop: asyncio.AbstractEventLoop,
        limit: int,
        max_line_size: int = 8190,
        max_headers: int = 32768,
        max_field_size: int = 8190,
        timer: Optional[BaseTimerContext] = None,
        code: Optional[int] = None,
        method: Optional[str] = None,
        readall: bool = False,
        payload_exception: Optional[Type[BaseException]] = None,
        response_with_body: bool = True,
        read_until_eof: bool = False,
        auto_decompress: bool = True,
    ) -> None:
        self.protocol = protocol
        self.loop = loop
        self.max_line_size = max_line_size
        self.max_headers = max_headers
        self.max_field_size = max_field_size
        self.timer = timer
        self.code = code
        self.method = method
        self.readall = readall
        self.payload_exception = payload_exception
        self.response_with_body = response_with_body
        self.read_until_eof = read_until_eof

        self._lines = []  # type: List[bytes]
        self._tail = b""
        self._upgraded = False
        self._payload = None
        self._payload_parser = None  # type: Optional[HttpPayloadParser]
        self._auto_decompress = auto_decompress
        self._limit = limit
        self._headers_parser = HeadersParser(max_line_size, max_headers, max_field_size)

    @abc.abstractmethod
    def parse_message(self, lines: List[bytes]) -> _MsgT:
        pass

    def feed_eof(self) -> Optional[_MsgT]:
        if self._payload_parser is not None:
            self._payload_parser.feed_eof()
            self._payload_parser = None
        else:
            # try to extract partial message
            if self._tail:
                self._lines.append(self._tail)

            if self._lines:
                if self._lines[-1] != "\r\n":
                    self._lines.append(b"")
                with suppress(Exception):
                    return self.parse_message(self._lines)
        return None

    def feed_data(
        self,
        data: bytes,
        SEP: bytes = b"\r\n",
        EMPTY: bytes = b"",
        CONTENT_LENGTH: istr = hdrs.CONTENT_LENGTH,
        METH_CONNECT: str = hdrs.METH_CONNECT,
        SEC_WEBSOCKET_KEY1: istr = hdrs.SEC_WEBSOCKET_KEY1,
    ) -> Tuple[List[Tuple[_MsgT, StreamReader]], bool, bytes]:

        messages = []

        if self._tail:
            data, self._tail = self._tail + data, b""

        data_len = len(data)
        start_pos = 0
        loop = self.loop

        while start_pos < data_len:

            # read HTTP message (request/response line + headers), \r\n\r\n
            # and split by lines
            if self._payload_parser is None and not self._upgraded:
                pos = data.find(SEP, start_pos)
                # consume \r\n
                if pos == start_pos and not self._lines:
                    start_pos = pos + 2
                    continue

                if pos >= start_pos:
                    # line found
                    self._lines.append(data[start_pos:pos])
                    start_pos = pos + 2

                    # \r\n\r\n found
                    if self._lines[-1] == EMPTY:
                        try:
                            msg = self.parse_message(self._lines)
                        finally:
                            self._lines.clear()

                        # payload length
                        length = msg.headers.get(CONTENT_LENGTH)
                        if length is not None:
                            try:
                                length = int(length)
                            except ValueError:
                                raise InvalidHeader(CONTENT_LENGTH)
                            if length < 0:
                                raise InvalidHeader(CONTENT_LENGTH)

                        # do not support old websocket spec
                        if SEC_WEBSOCKET_KEY1 in msg.headers:
                            raise InvalidHeader(SEC_WEBSOCKET_KEY1)

                        self._upgraded = msg.upgrade

                        method = getattr(msg, "method", self.method)

                        assert self.protocol is not None
                        # calculate payload
                        if (
                            (length is not None and length > 0)
                            or msg.chunked
                            and not msg.upgrade
                        ):
                            payload = StreamReader(
                                self.protocol,
                                timer=self.timer,
                                loop=loop,
                                limit=self._limit,
                            )
                            payload_parser = HttpPayloadParser(
                                payload,
                                length=length,
                                chunked=msg.chunked,
                                method=method,
                                compression=msg.compression,
                                code=self.code,
                                readall=self.readall,
                                response_with_body=self.response_with_body,
                                auto_decompress=self._auto_decompress,
                            )
                            if not payload_parser.done:
                                self._payload_parser = payload_parser
                        elif method == METH_CONNECT:
                            assert isinstance(msg, RawRequestMessage)
                            payload = StreamReader(
                                self.protocol,
                                timer=self.timer,
                                loop=loop,
                                limit=self._limit,
                            )
                            self._upgraded = True
                            self._payload_parser = HttpPayloadParser(
                                payload,
                                method=msg.method,
                                compression=msg.compression,
                                readall=True,
                                auto_decompress=self._auto_decompress,
                            )
                        else:
                            if (
                                getattr(msg, "code", 100) >= 199
                                and length is None
                                and self.read_until_eof
                            ):
                                payload = StreamReader(
                                    self.protocol,
                                    timer=self.timer,
                                    loop=loop,
                                    limit=self._limit,
                                )
                                payload_parser = HttpPayloadParser(
                                    payload,
                                    length=length,
                                    chunked=msg.chunked,
                                    method=method,
                                    compression=msg.compression,
                                    code=self.code,
                                    readall=True,
                                    response_with_body=self.response_with_body,
                                    auto_decompress=self._auto_decompress,
                                )
                                if not payload_parser.done:
                                    self._payload_parser = payload_parser
                            else:
                                payload = EMPTY_PAYLOAD  # type: ignore

                        messages.append((msg, payload))
                else:
                    self._tail = data[start_pos:]
                    data = EMPTY
                    break

            # no parser, just store
            elif self._payload_parser is None and self._upgraded:
                assert not self._lines
                break

            # feed payload
            elif data and start_pos < data_len:
                assert not self._lines
                assert self._payload_parser is not None
                try:
                    eof, data = self._payload_parser.feed_data(data[start_pos:])
                except BaseException as exc:
                    if self.payload_exception is not None:
                        self._payload_parser.payload.set_exception(
                            self.payload_exception(str(exc))
                        )
                    else:
                        self._payload_parser.payload.set_exception(exc)

                    eof = True
                    data = b""

                if eof:
                    start_pos = 0
                    data_len = len(data)
                    self._payload_parser = None
                    continue
            else:
                break

        if data and start_pos < data_len:
            data = data[start_pos:]
        else:
            data = EMPTY

        return messages, self._upgraded, data

    def parse_headers(
        self, lines: List[bytes]
    ) -> Tuple[
        "CIMultiDictProxy[str]", RawHeaders, Optional[bool], Optional[str], bool, bool
    ]:
        """Parses RFC 5322 headers from a stream.

        Line continuations are supported. Returns list of header name
        and value pairs. Header name is in upper case.
        """
        headers, raw_headers = self._headers_parser.parse_headers(lines)
        close_conn = None
        encoding = None
        upgrade = False
        chunked = False

        # keep-alive
        conn = headers.get(hdrs.CONNECTION)
        if conn:
            v = conn.lower()
            if v == "close":
                close_conn = True
            elif v == "keep-alive":
                close_conn = False
            elif v == "upgrade":
                upgrade = True

        # encoding
        enc = headers.get(hdrs.CONTENT_ENCODING)
        if enc:
            enc = enc.lower()
            if enc in ("gzip", "deflate", "br"):
                encoding = enc

        # chunking
        te = headers.get(hdrs.TRANSFER_ENCODING)
        if te and "chunked" in te.lower():
            chunked = True

        return (headers, raw_headers, close_conn, encoding, upgrade, chunked)

    def set_upgraded(self, val: bool) -> None:
        """Set connection upgraded (to websocket) mode.

        :param bool val: new state.
        """
        self._upgraded = val


class HttpRequestParser(HttpParser[RawRequestMessage]):
    """Read request status line. Exception .http_exceptions.BadStatusLine
    could be raised in case of any errors in status line.
    Returns RawRequestMessage.
    """

    def parse_message(self, lines: List[bytes]) -> RawRequestMessage:
        # request line
        line = lines[0].decode("utf-8", "surrogateescape")
        try:
            method, path, version = line.split(None, 2)
        except ValueError:
            raise BadStatusLine(line) from None

        if len(path) > self.max_line_size:
            raise LineTooLong(
                "Status line is too long", str(self.max_line_size), str(len(path))
            )

        # method
        if not METHRE.match(method):
            raise BadStatusLine(method)

        # version
        try:
            if version.startswith("HTTP/"):
                n1, n2 = version[5:].split(".", 1)
                version_o = HttpVersion(int(n1), int(n2))
            else:
                raise BadStatusLine(version)
        except Exception:
            raise BadStatusLine(version)

        # read headers
        (
            headers,
            raw_headers,
            close,
            compression,
            upgrade,
            chunked,
        ) = self.parse_headers(lines)

        if close is None:  # then the headers weren't set in the request
            if version_o <= HttpVersion10:  # HTTP 1.0 must asks to not close
                close = True
            else:  # HTTP 1.1 must ask to close.
                close = False

        return RawRequestMessage(
            method,
            path,
            version_o,
            headers,
            raw_headers,
            close,
            compression,
            upgrade,
            chunked,
            URL(path),
        )


class HttpResponseParser(HttpParser[RawResponseMessage]):
    """Read response status line and headers.

    BadStatusLine could be raised in case of any errors in status line.
    Returns RawResponseMessage"""

    def parse_message(self, lines: List[bytes]) -> RawResponseMessage:
        line = lines[0].decode("utf-8", "surrogateescape")
        try:
            version, status = line.split(None, 1)
        except ValueError:
            raise BadStatusLine(line) from None

        try:
            status, reason = status.split(None, 1)
        except ValueError:
            reason = ""

        if len(reason) > self.max_line_size:
            raise LineTooLong(
                "Status line is too long", str(self.max_line_size), str(len(reason))
            )

        # version
        match = VERSRE.match(version)
        if match is None:
            raise BadStatusLine(line)
        version_o = HttpVersion(int(match.group(1)), int(match.group(2)))

        # The status code is a three-digit number
        try:
            status_i = int(status)
        except ValueError:
            raise BadStatusLine(line) from None

        if status_i > 999:
            raise BadStatusLine(line)

        # read headers
        (
            headers,
            raw_headers,
            close,
            compression,
            upgrade,
            chunked,
        ) = self.parse_headers(lines)

        if close is None:
            close = version_o <= HttpVersion10

        return RawResponseMessage(
            version_o,
            status_i,
            reason.strip(),
            headers,
            raw_headers,
            close,
            compression,
            upgrade,
            chunked,
        )


class HttpPayloadParser:
    def __init__(
        self,
        payload: StreamReader,
        length: Optional[int] = None,
        chunked: bool = False,
        compression: Optional[str] = None,
        code: Optional[int] = None,
        method: Optional[str] = None,
        readall: bool = False,
        response_with_body: bool = True,
        auto_decompress: bool = True,
    ) -> None:
        self._length = 0
        self._type = ParseState.PARSE_NONE
        self._chunk = ChunkState.PARSE_CHUNKED_SIZE
        self._chunk_size = 0
        self._chunk_tail = b""
        self._auto_decompress = auto_decompress
        self.done = False

        # payload decompression wrapper
        if response_with_body and compression and self._auto_decompress:
            real_payload = DeflateBuffer(
                payload, compression
            )  # type: Union[StreamReader, DeflateBuffer]
        else:
            real_payload = payload

        # payload parser
        if not response_with_body:
            # don't parse payload if it's not expected to be received
            self._type = ParseState.PARSE_NONE
            real_payload.feed_eof()
            self.done = True

        elif chunked:
            self._type = ParseState.PARSE_CHUNKED
        elif length is not None:
            self._type = ParseState.PARSE_LENGTH
            self._length = length
            if self._length == 0:
                real_payload.feed_eof()
                self.done = True
        else:
            if readall and code != 204:
                self._type = ParseState.PARSE_UNTIL_EOF
            elif method in ("PUT", "POST"):
                internal_logger.warning(  # pragma: no cover
                    "Content-Length or Transfer-Encoding header is required"
                )
                self._type = ParseState.PARSE_NONE
                real_payload.feed_eof()
                self.done = True

        self.payload = real_payload

    def feed_eof(self) -> None:
        if self._type == ParseState.PARSE_UNTIL_EOF:
            self.payload.feed_eof()
        elif self._type == ParseState.PARSE_LENGTH:
            raise ContentLengthError(
                "Not enough data for satisfy content length header."
            )
        elif self._type == ParseState.PARSE_CHUNKED:
            raise TransferEncodingError(
                "Not enough data for satisfy transfer length header."
            )

    def feed_data(
        self, chunk: bytes, SEP: bytes = b"\r\n", CHUNK_EXT: bytes = b";"
    ) -> Tuple[bool, bytes]:
        # Read specified amount of bytes
        if self._type == ParseState.PARSE_LENGTH:
            required = self._length
            chunk_len = len(chunk)

            if required >= chunk_len:
                self._length = required - chunk_len
                self.payload.feed_data(chunk, chunk_len)
                if self._length == 0:
                    self.payload.feed_eof()
                    return True, b""
            else:
                self._length = 0
                self.payload.feed_data(chunk[:required], required)
                self.payload.feed_eof()
                return True, chunk[required:]

        # Chunked transfer encoding parser
        elif self._type == ParseState.PARSE_CHUNKED:
            if self._chunk_tail:
                chunk = self._chunk_tail + chunk
                self._chunk_tail = b""

            while chunk:

                # read next chunk size
                if self._chunk == ChunkState.PARSE_CHUNKED_SIZE:
                    pos = chunk.find(SEP)
                    if pos >= 0:
                        i = chunk.find(CHUNK_EXT, 0, pos)
                        if i >= 0:
                            size_b = chunk[:i]  # strip chunk-extensions
                        else:
                            size_b = chunk[:pos]

                        try:
                            size = int(bytes(size_b), 16)
                        except ValueError:
                            exc = TransferEncodingError(
                                chunk[:pos].decode("ascii", "surrogateescape")
                            )
                            self.payload.set_exception(exc)
                            raise exc from None

                        chunk = chunk[pos + 2 :]
                        if size == 0:  # eof marker
                            self._chunk = ChunkState.PARSE_MAYBE_TRAILERS
                        else:
                            self._chunk = ChunkState.PARSE_CHUNKED_CHUNK
                            self._chunk_size = size
                            self.payload.begin_http_chunk_receiving()
                    else:
                        self._chunk_tail = chunk
                        return False, b""

                # read chunk and feed buffer
                if self._chunk == ChunkState.PARSE_CHUNKED_CHUNK:
                    required = self._chunk_size
                    chunk_len = len(chunk)

                    if required > chunk_len:
                        self._chunk_size = required - chunk_len
                        self.payload.feed_data(chunk, chunk_len)
                        return False, b""
                    else:
                        self._chunk_size = 0
                        self.payload.feed_data(chunk[:required], required)
                        chunk = chunk[required:]
                        self._chunk = ChunkState.PARSE_CHUNKED_CHUNK_EOF
                        self.payload.end_http_chunk_receiving()

                # toss the CRLF at the end of the chunk
                if self._chunk == ChunkState.PARSE_CHUNKED_CHUNK_EOF:
                    if chunk[:2] == SEP:
                        chunk = chunk[2:]
                        self._chunk = ChunkState.PARSE_CHUNKED_SIZE
                    else:
                        self._chunk_tail = chunk
                        return False, b""

                # if stream does not contain trailer, after 0\r\n
                # we should get another \r\n otherwise
                # trailers needs to be skiped until \r\n\r\n
                if self._chunk == ChunkState.PARSE_MAYBE_TRAILERS:
                    head = chunk[:2]
                    if head == SEP:
                        # end of stream
                        self.payload.feed_eof()
                        return True, chunk[2:]
                    # Both CR and LF, or only LF may not be received yet. It is
                    # expected that CRLF or LF will be shown at the very first
                    # byte next time, otherwise trailers should come. The last
                    # CRLF which marks the end of response might not be
                    # contained in the same TCP segment which delivered the
                    # size indicator.
                    if not head:
                        return False, b""
                    if head == SEP[:1]:
                        self._chunk_tail = head
                        return False, b""
                    self._chunk = ChunkState.PARSE_TRAILERS

                # read and discard trailer up to the CRLF terminator
                if self._chunk == ChunkState.PARSE_TRAILERS:
                    pos = chunk.find(SEP)
                    if pos >= 0:
                        chunk = chunk[pos + 2 :]
                        self._chunk = ChunkState.PARSE_MAYBE_TRAILERS
                    else:
                        self._chunk_tail = chunk
                        return False, b""

        # Read all bytes until eof
        elif self._type == ParseState.PARSE_UNTIL_EOF:
            self.payload.feed_data(chunk, len(chunk))

        return False, b""


class DeflateBuffer:
    """DeflateStream decompress stream and feed data into specified stream."""

    def __init__(self, out: StreamReader, encoding: Optional[str]) -> None:
        self.out = out
        self.size = 0
        self.encoding = encoding
        self._started_decoding = False

        if encoding == "br":
            if not HAS_BROTLI:  # pragma: no cover
                raise ContentEncodingError(
                    "Can not decode content-encoding: brotli (br). "
                    "Please install `Brotli`"
                )

            class BrotliDecoder:
                # Supports both 'brotlipy' and 'Brotli' packages
                # since they share an import name. The top branches
                # are for 'brotlipy' and bottom branches for 'Brotli'
                def __init__(self) -> None:
                    self._obj = brotli.Decompressor()

                def decompress(self, data: bytes) -> bytes:
                    if hasattr(self._obj, "decompress"):
                        return self._obj.decompress(data)
                    return self._obj.process(data)

                def flush(self) -> bytes:
                    if hasattr(self._obj, "flush"):
                        return self._obj.flush()
                    return b""

            self.decompressor = BrotliDecoder()  # type: Any
        else:
            zlib_mode = 16 + zlib.MAX_WBITS if encoding == "gzip" else zlib.MAX_WBITS
            self.decompressor = zlib.decompressobj(wbits=zlib_mode)

    def set_exception(self, exc: BaseException) -> None:
        self.out.set_exception(exc)

    def feed_data(self, chunk: bytes, size: int) -> None:
        if not size:
            return

        self.size += size

        # RFC1950
        # bits 0..3 = CM = 0b1000 = 8 = "deflate"
        # bits 4..7 = CINFO = 1..7 = windows size.
        if (
            not self._started_decoding
            and self.encoding == "deflate"
            and chunk[0] & 0xF != 8
        ):
            # Change the decoder to decompress incorrectly compressed data
            # Actually we should issue a warning about non-RFC-compliant data.
            self.decompressor = zlib.decompressobj(wbits=-zlib.MAX_WBITS)

        try:
            chunk = self.decompressor.decompress(chunk)
        except Exception:
            raise ContentEncodingError(
                "Can not decode content-encoding: %s" % self.encoding
            )

        self._started_decoding = True

        if chunk:
            self.out.feed_data(chunk, len(chunk))

    def feed_eof(self) -> None:
        chunk = self.decompressor.flush()

        if chunk or self.size > 0:
            self.out.feed_data(chunk, len(chunk))
            if self.encoding == "deflate" and not self.decompressor.eof:
                raise ContentEncodingError("deflate")

        self.out.feed_eof()

    def begin_http_chunk_receiving(self) -> None:
        self.out.begin_http_chunk_receiving()

    def end_http_chunk_receiving(self) -> None:
        self.out.end_http_chunk_receiving()


HttpRequestParserPy = HttpRequestParser
HttpResponseParserPy = HttpResponseParser
RawRequestMessagePy = RawRequestMessage
RawResponseMessagePy = RawResponseMessage

try:
    if not NO_EXTENSIONS:
        from ._http_parser import (  # type: ignore
            HttpRequestParser,
            HttpResponseParser,
            RawRequestMessage,
            RawResponseMessage,
        )

        HttpRequestParserC = HttpRequestParser
        HttpResponseParserC = HttpResponseParser
        RawRequestMessageC = RawRequestMessage
        RawResponseMessageC = RawResponseMessage
except ImportError:  # pragma: no cover
    pass