# Source code for scrapy.core.downloader.handlers.http11

    """Download handlers for http and https schemes"""

    from __future__ import annotations

    import ipaddress
    import logging
    import re
    from contextlib import suppress
    from io import BytesIO
    from time import time
    from typing import TYPE_CHECKING, Any, TypedDict, TypeVar, cast
    from urllib.parse import urldefrag, urlparse

    from twisted.internet import ssl
    from twisted.internet.defer import CancelledError, Deferred, succeed
    from twisted.internet.endpoints import TCP4ClientEndpoint
    from twisted.internet.error import TimeoutError as TxTimeoutError
    from twisted.internet.protocol import Factory, Protocol, connectionDone
    from twisted.python.failure import Failure
    from twisted.web.client import (
        URI,
        Agent,
        HTTPConnectionPool,
        ResponseDone,
        ResponseFailed,
    )
    from twisted.web.client import Response as TxResponse
    from twisted.web.http import PotentialDataLoss, _DataLoss
    from twisted.web.http_headers import Headers as TxHeaders
    from twisted.web.iweb import UNKNOWN_LENGTH, IBodyProducer, IPolicyForHTTPS, IResponse
    from zope.interface import implementer

    from scrapy import Request, signals
    from scrapy.core.downloader.contextfactory import load_context_factory_from_settings
    from scrapy.core.downloader.handlers.base import BaseDownloadHandler
    from scrapy.exceptions import StopDownload
    from scrapy.http import Headers, Response
    from scrapy.responsetypes import responsetypes
    from scrapy.utils.defer import maybe_deferred_to_future
    from scrapy.utils.deprecate import warn_on_deprecated_spider_attribute
    from scrapy.utils.httpobj import urlparse_cached
    from scrapy.utils.python import to_bytes, to_unicode
    from scrapy.utils.url import add_http_if_no_scheme

    if TYPE_CHECKING:
        from twisted.internet.base import ReactorBase
        from twisted.internet.interfaces import IConsumer

        # typing.NotRequired requires Python 3.11
        from typing_extensions import NotRequired

        from scrapy.crawler import Crawler

    logger = logging.getLogger(__name__)

    _T = TypeVar("_T")

    class _ResultT(TypedDict):
        txresponse: TxResponse
        body: bytes
        flags: list[str] | None
        certificate: ssl.Certificate | None
        ip_address: ipaddress.IPv4Address | ipaddress.IPv6Address | None
        failure: NotRequired[Failure | None]

    class HTTP11DownloadHandler(BaseDownloadHandler):
        def __init__(self, crawler: Crawler):
            super().__init__(crawler)
            self._crawler = crawler

            from twisted.internet import reactor

            self._pool: HTTPConnectionPool = HTTPConnectionPool(reactor, persistent=True)
            self._pool.maxPersistentPerHost = crawler.settings.getint(
                "CONCURRENT_REQUESTS_PER_DOMAIN"
            )
            self._pool._factory.noisy = False

            self._contextFactory: IPolicyForHTTPS = load_context_factory_from_settings(
                crawler.settings, crawler
            )
            self._default_maxsize: int = crawler.settings.getint("DOWNLOAD_MAXSIZE")
            self._default_warnsize: int = crawler.settings.getint("DOWNLOAD_WARNSIZE")
            self._fail_on_dataloss: bool = crawler.settings.getbool(
                "DOWNLOAD_FAIL_ON_DATALOSS"
            )
            self._disconnect_timeout: int = 1

        async def download_request(self, request: Request) -> Response:
            """Return a deferred for the HTTP download"""
            if hasattr(self._crawler.spider, "download_maxsize"):  # pragma: no cover
                warn_on_deprecated_spider_attribute("download_maxsize", "DOWNLOAD_MAXSIZE")
            if hasattr(self._crawler.spider, "download_warnsize"):  # pragma: no cover
                warn_on_deprecated_spider_attribute(
                    "download_warnsize", "DOWNLOAD_WARNSIZE"
                )

            agent = ScrapyAgent(
                contextFactory=self._contextFactory,
                pool=self._pool,
                maxsize=getattr(
                    self._crawler.spider, "download_maxsize", self._default_maxsize
                ),
                warnsize=getattr(
                    self._crawler.spider, "download_warnsize", self._default_warnsize
                ),
                fail_on_dataloss=self._fail_on_dataloss,
                crawler=self._crawler,
            )
            return await maybe_deferred_to_future(agent.download_request(request))

        async def close(self) -> None:
            from twisted.internet import reactor

            d: Deferred[None] = self._pool.closeCachedConnections()
            # closeCachedConnections will hang on network or server issues, so
            # we'll manually timeout the deferred.
            #
            # Twisted issue addressing this problem can be found here:
            # https://github.com/twisted/twisted/issues/7738
            #
            # closeCachedConnections doesn't handle external errbacks, so we'll
            # issue a callback after `_disconnect_timeout` seconds.
            #
            # See also https://github.com/scrapy/scrapy/issues/2653
            delayed_call = reactor.callLater(self._disconnect_timeout, d.callback, [])

            try:
                await maybe_deferred_to_future(d)
            finally:
                if delayed_call.active():
                    delayed_call.cancel()

    class TunnelError(Exception):
        """An HTTP CONNECT tunnel could not be established by the proxy."""

    class TunnelingTCP4ClientEndpoint(TCP4ClientEndpoint):
        """An endpoint that tunnels through proxies to allow HTTPS downloads. To
        accomplish that, this endpoint sends an HTTP CONNECT to the proxy.
        The HTTP CONNECT is always sent when using this endpoint, I think this could
        be improved as the CONNECT will be redundant if the connection associated
        with this endpoint comes from the pool and a CONNECT has already been issued
        for it.
        """

        _truncatedLength = 1000
        _responseAnswer = (
            r"HTTP/1\.. (?P<status>\d{3})(?P<reason>.{," + str(_truncatedLength) + r"})"
        )
        _responseMatcher = re.compile(_responseAnswer.encode())

        def __init__(
            self,
            reactor: ReactorBase,
            host: str,
            port: int,
            proxyConf: tuple[str, int, bytes | None],
            contextFactory: IPolicyForHTTPS,
            timeout: float = 30,
            bindAddress: tuple[str, int] | None = None,
        ):
            proxyHost, proxyPort, self._proxyAuthHeader = proxyConf
            super().__init__(reactor, proxyHost, proxyPort, timeout, bindAddress)
            self._tunnelReadyDeferred: Deferred[Protocol] = Deferred()
            self._tunneledHost: str = host
            self._tunneledPort: int = port
            self._contextFactory: IPolicyForHTTPS = contextFactory
            self._connectBuffer: bytearray = bytearray()

        def requestTunnel(self, protocol: Protocol) -> Protocol:
            """Asks the proxy to open a tunnel."""
            assert protocol.transport
            tunnelReq = tunnel_request_data(
                self._tunneledHost, self._tunneledPort, self._proxyAuthHeader
            )
            protocol.transport.write(tunnelReq)
            self._protocolDataReceived = protocol.dataReceived
            protocol.dataReceived = self.processProxyResponse  # type: ignore[method-assign]
            self._protocol = protocol
            return protocol

        def processProxyResponse(self, data: bytes) -> None:
            """Processes the response from the proxy. If the tunnel is successfully
            created, notifies the client that we are ready to send requests. If not
            raises a TunnelError.
            """
            assert self._protocol.transport
            self._connectBuffer += data
            # make sure that enough (all) bytes are consumed
            # and that we've got all HTTP headers (ending with a blank line)
            # from the proxy so that we don't send those bytes to the TLS layer
            #
            # see https://github.com/scrapy/scrapy/issues/2491
            if b"\r\n\r\n" not in self._connectBuffer:
                return
            self._protocol.dataReceived = self._protocolDataReceived  # type: ignore[method-assign]
            respm = TunnelingTCP4ClientEndpoint._responseMatcher.match(self._connectBuffer)
            if respm and int(respm.group("status")) == 200:
                # set proper Server Name Indication extension
                sslOptions = self._contextFactory.creatorForNetloc(  # type: ignore[call-arg,misc]
                    self._tunneledHost, self._tunneledPort
                )
                self._protocol.transport.startTLS(sslOptions, self._protocolFactory)
                self._tunnelReadyDeferred.callback(self._protocol)
            else:
                extra: Any
                if respm:
                    extra = {
                        "status": int(respm.group("status")),
                        "reason": respm.group("reason").strip(),
                    }
                else:
                    extra = data[: self._truncatedLength]
                self._tunnelReadyDeferred.errback(
                    TunnelError(
                        "Could not open CONNECT tunnel with proxy "
                        f"{self._host}:{self._port} [{extra!r}]"
                    )
                )

        def connectFailed(self, reason: Failure) -> None:
            """Propagates the errback to the appropriate deferred."""
            self._tunnelReadyDeferred.errback(reason)

        def connect(self, protocolFactory: Factory) -> Deferred[Protocol]:
            self._protocolFactory = protocolFactory
            connectDeferred = super().connect(protocolFactory)
            connectDeferred.addCallback(self.requestTunnel)
            connectDeferred.addErrback(self.connectFailed)
            return self._tunnelReadyDeferred

    def tunnel_request_data(
        host: str, port: int, proxy_auth_header: bytes | None = None
    ) -> bytes:
        r"""
        Return binary content of a CONNECT request.

        >>> from scrapy.utils.python import to_unicode as s
        >>> s(tunnel_request_data("example.com", 8080))
        'CONNECT example.com:8080 HTTP/1.1\r\nHost: example.com:8080\r\n\r\n'
        >>> s(tunnel_request_data("example.com", 8080, b"123"))
        'CONNECT example.com:8080 HTTP/1.1\r\nHost: example.com:8080\r\nProxy-Authorization: 123\r\n\r\n'
        >>> s(tunnel_request_data(b"example.com", "8090"))
        'CONNECT example.com:8090 HTTP/1.1\r\nHost: example.com:8090\r\n\r\n'
        """
        host_value = to_bytes(host, encoding="ascii") + b":" + to_bytes(str(port))
        tunnel_req = b"CONNECT " + host_value + b" HTTP/1.1\r\n"
        tunnel_req += b"Host: " + host_value + b"\r\n"
        if proxy_auth_header:
            tunnel_req += b"Proxy-Authorization: " + proxy_auth_header + b"\r\n"
        tunnel_req += b"\r\n"
        return tunnel_req

    class TunnelingAgent(Agent):
        """An agent that uses a L{TunnelingTCP4ClientEndpoint} to make HTTPS
        downloads. It may look strange that we have chosen to subclass Agent and not
        ProxyAgent but consider that after the tunnel is opened the proxy is
        transparent to the client; thus the agent should behave like there is no
        proxy involved.
        """

        def __init__(
            self,
            *,
            reactor: ReactorBase,
            proxyConf: tuple[str, int, bytes | None],
            contextFactory: IPolicyForHTTPS,
            connectTimeout: float | None = None,
            bindAddress: bytes | None = None,
            pool: HTTPConnectionPool | None = None,
        ):
            super().__init__(reactor, contextFactory, connectTimeout, bindAddress, pool)
            self._proxyConf: tuple[str, int, bytes | None] = proxyConf
            self._contextFactory: IPolicyForHTTPS = contextFactory

        def _getEndpoint(self, uri: URI) -> TunnelingTCP4ClientEndpoint:
            return TunnelingTCP4ClientEndpoint(
                reactor=self._reactor,
                host=uri.host,
                port=uri.port,
                proxyConf=self._proxyConf,
                contextFactory=self._contextFactory,
                timeout=self._endpointFactory._connectTimeout,
                bindAddress=self._endpointFactory._bindAddress,
            )

        def _requestWithEndpoint(
            self,
            key: Any,
            endpoint: TCP4ClientEndpoint,
            method: bytes,
            parsedURI: URI,
            headers: TxHeaders | None,
            bodyProducer: IBodyProducer | None,
            requestPath: bytes,
        ) -> Deferred[IResponse]:
            # proxy host and port are required for HTTP pool `key`
            # otherwise, same remote host connection request could reuse
            # a cached tunneled connection to a different proxy
            key += self._proxyConf
            return super()._requestWithEndpoint(
                key=key,
                endpoint=endpoint,
                method=method,
                parsedURI=parsedURI,
                headers=headers,
                bodyProducer=bodyProducer,
                requestPath=requestPath,
            )

    class ScrapyProxyAgent(Agent):
        def __init__(
            self,
            reactor: ReactorBase,
            proxyURI: bytes,
            connectTimeout: float | None = None,
            bindAddress: bytes | None = None,
            pool: HTTPConnectionPool | None = None,
        ):
            super().__init__(
                reactor=reactor,
                connectTimeout=connectTimeout,
                bindAddress=bindAddress,
                pool=pool,
            )
            self._proxyURI: URI = URI.fromBytes(proxyURI)

        def request(
            self,
            method: bytes,
            uri: bytes,
            headers: TxHeaders | None = None,
            bodyProducer: IBodyProducer | None = None,
        ) -> Deferred[IResponse]:
            """
            Issue a new request via the configured proxy.
            """
            # Cache *all* connections under the same key, since we are only
            # connecting to a single destination, the proxy:
            return self._requestWithEndpoint(
                key=(b"http-proxy", self._proxyURI.host, self._proxyURI.port),
                endpoint=self._getEndpoint(self._proxyURI),
                method=method,
                parsedURI=URI.fromBytes(uri),
                headers=headers,
                bodyProducer=bodyProducer,
                requestPath=uri,
            )

    class ScrapyAgent:
        _Agent = Agent
        _ProxyAgent = ScrapyProxyAgent
        _TunnelingAgent = TunnelingAgent

        def __init__(
            self,
            *,
            contextFactory: IPolicyForHTTPS,
            connectTimeout: float = 10,
            bindAddress: bytes | None = None,
            pool: HTTPConnectionPool | None = None,
            maxsize: int = 0,
            warnsize: int = 0,
            fail_on_dataloss: bool = True,
            crawler: Crawler,
        ):
            self._contextFactory: IPolicyForHTTPS = contextFactory
            self._connectTimeout: float = connectTimeout
            self._bindAddress: bytes | None = bindAddress
            self._pool: HTTPConnectionPool | None = pool
            self._maxsize: int = maxsize
            self._warnsize: int = warnsize
            self._fail_on_dataloss: bool = fail_on_dataloss
            self._txresponse: TxResponse | None = None
            self._crawler: Crawler = crawler

        def _get_agent(self, request: Request, timeout: float) -> Agent:
            from twisted.internet import reactor

            bindaddress = request.meta.get("bindaddress") or self._bindAddress
            proxy = request.meta.get("proxy")
            if proxy:
                proxy = add_http_if_no_scheme(proxy)
                proxy_parsed = urlparse(proxy)
                proxy_host = proxy_parsed.hostname
                proxy_port = proxy_parsed.port
                if not proxy_port:
                    proxy_port = 443 if proxy_parsed.scheme == "https" else 80
                if urlparse_cached(request).scheme == "https":
                    assert proxy_host is not None
                    proxyAuth = request.headers.get(b"Proxy-Authorization", None)
                    proxyConf = (proxy_host, proxy_port, proxyAuth)
                    return self._TunnelingAgent(
                        reactor=reactor,
                        proxyConf=proxyConf,
                        contextFactory=self._contextFactory,
                        connectTimeout=timeout,
                        bindAddress=bindaddress,
                        pool=self._pool,
                    )
                return self._ProxyAgent(
                    reactor=reactor,
                    proxyURI=to_bytes(proxy, encoding="ascii"),
                    connectTimeout=timeout,
                    bindAddress=bindaddress,
                    pool=self._pool,
                )

            return self._Agent(
                reactor=reactor,
                contextFactory=self._contextFactory,
                connectTimeout=timeout,
                bindAddress=bindaddress,
                pool=self._pool,
            )

        def download_request(self, request: Request) -> Deferred[Response]:
            from twisted.internet import reactor

            timeout = request.meta.get("download_timeout") or self._connectTimeout
            agent = self._get_agent(request, timeout)

            # request details
            url = urldefrag(request.url)[0]
            method = to_bytes(request.method)
            headers = TxHeaders(request.headers)
            if isinstance(agent, self._TunnelingAgent):
                headers.removeHeader(b"Proxy-Authorization")
            bodyproducer = _RequestBodyProducer(request.body) if request.body else None
            start_time = time()
            d: Deferred[IResponse] = agent.request(
                method,
                to_bytes(url, encoding="ascii"),
                headers,
                cast("IBodyProducer", bodyproducer),
            )
            # set download latency
            d.addCallback(self._cb_latency, request, start_time)
            # response body is ready to be consumed
            d2: Deferred[_ResultT] = d.addCallback(self._cb_bodyready, request)
            d3: Deferred[Response] = d2.addCallback(self._cb_bodydone, request, url)
            # check download timeout
            self._timeout_cl = reactor.callLater(timeout, d3.cancel)
            d3.addBoth(self._cb_timeout, request, url, timeout)
            return d3

        def _cb_timeout(self, result: _T, request: Request, url: str, timeout: float) -> _T:
            if self._timeout_cl.active():
                self._timeout_cl.cancel()
                return result
            # needed for HTTPS requests, otherwise _ResponseReader doesn't
            # receive connectionLost()
            if self._txresponse:
                self._txresponse._transport.stopProducing()

            raise TxTimeoutError(f"Getting {url} took longer than {timeout} seconds.")

        def _cb_latency(self, result: _T, request: Request, start_time: float) -> _T:
            request.meta["download_latency"] = time() - start_time
            return result

        @staticmethod
        def _headers_from_twisted_response(response: TxResponse) -> Headers:
            headers = Headers()
            if response.length != UNKNOWN_LENGTH:
                headers[b"Content-Length"] = str(response.length).encode()
            headers.update(response.headers.getAllRawHeaders())
            return headers

        def _cb_bodyready(
            self, txresponse: TxResponse, request: Request
        ) -> _ResultT | Deferred[_ResultT]:
            headers_received_result = self._crawler.signals.send_catch_log(
                signal=signals.headers_received,
                headers=self._headers_from_twisted_response(txresponse),
                body_length=txresponse.length,
                request=request,
                spider=self._crawler.spider,
            )
            for handler, result in headers_received_result:
                if isinstance(result, Failure) and isinstance(result.value, StopDownload):
                    logger.debug(
                        "Download stopped for %(request)s from signal handler %(handler)s",
                        {"request": request, "handler": handler.__qualname__},
                    )
                    txresponse._transport.stopProducing()
                    txresponse._transport.loseConnection()
                    return {
                        "txresponse": txresponse,
                        "body": b"",
                        "flags": ["download_stopped"],
                        "certificate": None,
                        "ip_address": None,
                        "failure": result if result.value.fail else None,
                    }

            # deliverBody hangs for responses without body
            if txresponse.length == 0:
                return {
                    "txresponse": txresponse,
                    "body": b"",
                    "flags": None,
                    "certificate": None,
                    "ip_address": None,
                }

            maxsize = request.meta.get("download_maxsize", self._maxsize)
            warnsize = request.meta.get("download_warnsize", self._warnsize)
            expected_size = txresponse.length if txresponse.length != UNKNOWN_LENGTH else -1
            fail_on_dataloss = request.meta.get(
                "download_fail_on_dataloss", self._fail_on_dataloss
            )

            if maxsize and expected_size > maxsize:
                warning_msg = (
                    "Cancelling download of %(url)s: expected response "
                    "size (%(size)s) larger than download max size (%(maxsize)s)."
                )
                warning_args = {
                    "url": request.url,
                    "size": expected_size,
                    "maxsize": maxsize,
                }

                logger.warning(warning_msg, warning_args)

                txresponse._transport.loseConnection()
                raise CancelledError(warning_msg % warning_args)

            if warnsize and expected_size > warnsize:
                logger.warning(
                    "Expected response size (%(size)s) larger than "
                    "download warn size (%(warnsize)s) in request %(request)s.",
                    {"size": expected_size, "warnsize": warnsize, "request": request},
                )

            def _cancel(_: Any) -> None:
                # Abort connection immediately.
                txresponse._transport._producer.abortConnection()

            d: Deferred[_ResultT] = Deferred(_cancel)
            txresponse.deliverBody(
                _ResponseReader(
                    finished=d,
                    txresponse=txresponse,
                    request=request,
                    maxsize=maxsize,
                    warnsize=warnsize,
                    fail_on_dataloss=fail_on_dataloss,
                    crawler=self._crawler,
                )
            )

            # save response for timeouts
            self._txresponse = txresponse

            return d

        def _cb_bodydone(
            self, result: _ResultT, request: Request, url: str
        ) -> Response | Failure:
            headers = self._headers_from_twisted_response(result["txresponse"])
            respcls = responsetypes.from_args(headers=headers, url=url, body=result["body"])
            try:
                version = result["txresponse"].version
                protocol = f"{to_unicode(version[0])}/{version[1]}.{version[2]}"
            except (AttributeError, TypeError, IndexError):
                protocol = None
            response = respcls(
                url=url,
                status=int(result["txresponse"].code),
                headers=headers,
                body=result["body"],
                flags=result["flags"],
                certificate=result["certificate"],
                ip_address=result["ip_address"],
                protocol=protocol,
            )
            if result.get("failure"):
                assert result["failure"]
                result["failure"].value.response = response
                return result["failure"]
            return response

    @implementer(IBodyProducer)
    class _RequestBodyProducer:
        def __init__(self, body: bytes):
            self.body = body
            self.length = len(body)

        def startProducing(self, consumer: IConsumer) -> Deferred[None]:
            consumer.write(self.body)
            return succeed(None)

        def pauseProducing(self) -> None:
            pass

        def stopProducing(self) -> None:
            pass

    class _ResponseReader(Protocol):
        def __init__(
            self,
            finished: Deferred[_ResultT],
            txresponse: TxResponse,
            request: Request,
            maxsize: int,
            warnsize: int,
            fail_on_dataloss: bool,
            crawler: Crawler,
        ):
            self._finished: Deferred[_ResultT] = finished
            self._txresponse: TxResponse = txresponse
            self._request: Request = request
            self._bodybuf: BytesIO = BytesIO()
            self._maxsize: int = maxsize
            self._warnsize: int = warnsize
            self._fail_on_dataloss: bool = fail_on_dataloss
            self._fail_on_dataloss_warned: bool = False
            self._reached_warnsize: bool = False
            self._bytes_received: int = 0
            self._certificate: ssl.Certificate | None = None
            self._ip_address: ipaddress.IPv4Address | ipaddress.IPv6Address | None = None
            self._crawler: Crawler = crawler

        def _finish_response(
            self, flags: list[str] | None = None, failure: Failure | None = None
        ) -> None:
            self._finished.callback(
                {
                    "txresponse": self._txresponse,
                    "body": self._bodybuf.getvalue(),
                    "flags": flags,
                    "certificate": self._certificate,
                    "ip_address": self._ip_address,
                    "failure": failure,
                }
            )

        def connectionMade(self) -> None:
            assert self.transport
            if self._certificate is None:
                with suppress(AttributeError):
                    self._certificate = ssl.Certificate(
                        self.transport._producer.getPeerCertificate()
                    )

            if self._ip_address is None:
                self._ip_address = ipaddress.ip_address(
                    self.transport._producer.getPeer().host
                )

        def dataReceived(self, bodyBytes: bytes) -> None:
            # This maybe called several times after cancel was called with buffered data.
            if self._finished.called:
                return

            assert self.transport
            self._bodybuf.write(bodyBytes)
            self._bytes_received += len(bodyBytes)

            bytes_received_result = self._crawler.signals.send_catch_log(
                signal=signals.bytes_received,
                data=bodyBytes,
                request=self._request,
                spider=self._crawler.spider,
            )
            for handler, result in bytes_received_result:
                if isinstance(result, Failure) and isinstance(result.value, StopDownload):
                    logger.debug(
                        "Download stopped for %(request)s from signal handler %(handler)s",
                        {"request": self._request, "handler": handler.__qualname__},
                    )
                    self.transport.stopProducing()
                    self.transport.loseConnection()
                    failure = result if result.value.fail else None
                    self._finish_response(flags=["download_stopped"], failure=failure)

            if self._maxsize and self._bytes_received > self._maxsize:
                logger.warning(
                    "Received (%(bytes)s) bytes larger than download "
                    "max size (%(maxsize)s) in request %(request)s.",
                    {
                        "bytes": self._bytes_received,
                        "maxsize": self._maxsize,
                        "request": self._request,
                    },
                )
                # Clear buffer earlier to avoid keeping data in memory for a long time.
                self._bodybuf.truncate(0)
                self._finished.cancel()

            if (
                self._warnsize
                and self._bytes_received > self._warnsize
                and not self._reached_warnsize
            ):
                self._reached_warnsize = True
                logger.warning(
                    "Received more bytes than download "
                    "warn size (%(warnsize)s) in request %(request)s.",
                    {"warnsize": self._warnsize, "request": self._request},
                )

        def connectionLost(self, reason: Failure = connectionDone) -> None:
            if self._finished.called:
                return

            if reason.check(ResponseDone):
                self._finish_response()
                return

            if reason.check(PotentialDataLoss):
                self._finish_response(flags=["partial"])
                return

            if reason.check(ResponseFailed) and any(
                r.check(_DataLoss) for r in reason.value.reasons
            ):
                if not self._fail_on_dataloss:
                    self._finish_response(flags=["dataloss"])
                    return

                if not self._fail_on_dataloss_warned:
                    logger.warning(
                        "Got data loss in %s. If you want to process broken "
                        "responses set the setting DOWNLOAD_FAIL_ON_DATALOSS = False"
                        " -- This message won't be shown in further requests",
                        self._txresponse.request.absoluteURI.decode(),
                    )
                    self._fail_on_dataloss_warned = True

            self._finished.errback(reason)