urllib3

class HTTPConnectionPool(ConnectionPool, RequestMethods):
    """
    Thread-safe connection pool for one host.

    :param host:
        Host used for this HTTP Connection (e.g. "localhost"), passed into
        :class:`http.client.HTTPConnection`.

    :param port:
        Port used for this HTTP Connection (None is equivalent to 80), passed
        into :class:`http.client.HTTPConnection`.

    :param strict:
        Causes BadStatusLine to be raised if the status line can't be parsed
        as a valid HTTP/1.0 or 1.1 status line, passed into
        :class:`http.client.HTTPConnection`.

        .. note::
           Only works in Python 2. This parameter is ignored in Python 3.

    :param timeout:
        Socket timeout in seconds for each individual connection. This can
        be a float or integer, which sets the timeout for the HTTP request,
        or an instance of :class:`urllib3.util.Timeout` which gives you more
        fine-grained control over request timeouts. After the constructor has
        been parsed, this is always a `urllib3.util.Timeout` object.

    :param maxsize:
        Number of connections to save that can be reused. More than 1 is useful
        in multithreaded situations. If ``block`` is set to False, more
        connections will be created but they will not be saved once they've
        been used.

    :param block:
        If set to True, no more than ``maxsize`` connections will be used at
        a time. When no free connections are available, the call will block
        until a connection has been released. This is a useful side effect for
        particular multithreaded situations where one does not want to use more
        than maxsize connections per host to prevent flooding.

    :param headers:
        Headers to include with all requests, unless other headers are given
        explicitly.

    :param retries:
        Retry configuration to use by default with requests in this pool.

    :param _proxy:
        Parsed proxy URL, should not be used directly, instead, see
        :class:`urllib3.ProxyManager`

    :param _proxy_headers:
        A dictionary with proxy headers, should not be used directly,
        instead, see :class:`urllib3.ProxyManager`

    :param \\**conn_kw:
        Additional parameters are used to create fresh :class:`urllib3.connection.HTTPConnection`,
        :class:`urllib3.connection.HTTPSConnection` instances.
    """

    scheme = "http"
    ConnectionCls = HTTPConnection
    ResponseCls = HTTPResponse

    def __init__(
        self,
        host,
        port=None,
        strict=False,
        timeout=Timeout.DEFAULT_TIMEOUT,
        maxsize=1,
        block=False,
        headers=None,
        retries=None,
        _proxy=None,
        _proxy_headers=None,
        _proxy_config=None,
        **conn_kw
    ):
        ConnectionPool.__init__(self, host, port)
        RequestMethods.__init__(self, headers)

        self.strict = strict

        if not isinstance(timeout, Timeout):
            timeout = Timeout.from_float(timeout)

        if retries is None:
            retries = Retry.DEFAULT

        self.timeout = timeout
        self.retries = retries

        self.pool = self.QueueCls(maxsize)
        self.block = block

        self.proxy = _proxy
        self.proxy_headers = _proxy_headers or {}
        self.proxy_config = _proxy_config

        # Fill the queue up so that doing get() on it will block properly
        for _ in xrange(maxsize):
            self.pool.put(None)

        # These are mostly for testing and debugging purposes.
        self.num_connections = 0
        self.num_requests = 0
        self.conn_kw = conn_kw

        if self.proxy:
            # Enable Nagle's algorithm for proxies, to avoid packet fragmentation.
            # We cannot know if the user has added default socket options, so we cannot replace the
            # list.
            self.conn_kw.setdefault("socket_options", [])

            self.conn_kw["proxy"] = self.proxy
            self.conn_kw["proxy_config"] = self.proxy_config

    def _new_conn(self):
        """
        Return a fresh :class:`HTTPConnection`.
        """
        self.num_connections += 1
        log.debug(
            "Starting new HTTP connection (%d): %s:%s",
            self.num_connections,
            self.host,
            self.port or "80",
        )

        conn = self.ConnectionCls(
            host=self.host,
            port=self.port,
            timeout=self.timeout.connect_timeout,
            strict=self.strict,
            **self.conn_kw
        )
        return conn

    def _get_conn(self, timeout=None):
        """
        Get a connection. Will return a pooled connection if one is available.

        If no connections are available and :prop:`.block` is ``False``, then a
        fresh connection is returned.

        :param timeout:
            Seconds to wait before giving up and raising
            :class:`urllib3.exceptions.EmptyPoolError` if the pool is empty and
            :prop:`.block` is ``True``.
        """
        conn = None
        try:
            conn = self.pool.get(block=self.block, timeout=timeout)

        except AttributeError:  # self.pool is None
            raise ClosedPoolError(self, "Pool is closed.")

        except queue.Empty:
            if self.block:
                raise EmptyPoolError(
                    self,
                    "Pool reached maximum size and no more connections are allowed.",
                )
            pass  # Oh well, we'll create a new connection then

        # If this is a persistent connection, check if it got disconnected
        if conn and is_connection_dropped(conn):
            log.debug("Resetting dropped connection: %s", self.host)
            conn.close()
            if getattr(conn, "auto_open", 1) == 0:
                # This is a proxied connection that has been mutated by
                # http.client._tunnel() and cannot be reused (since it would
                # attempt to bypass the proxy)
                conn = None

        return conn or self._new_conn()

    def _put_conn(self, conn):
        """
        Put a connection back into the pool.

        :param conn:
            Connection object for the current host and port as returned by
            :meth:`._new_conn` or :meth:`._get_conn`.

        If the pool is already full, the connection is closed and discarded
        because we exceeded maxsize. If connections are discarded frequently,
        then maxsize should be increased.

        If the pool is closed, then the connection will be closed and discarded.
        """
        try:
            self.pool.put(conn, block=False)
            return  # Everything is dandy, done.
        except AttributeError:
            # self.pool is None.
            pass
        except queue.Full:
            # This should never happen if self.block == True
            log.warning("Connection pool is full, discarding connection: %s", self.host)

        # Connection never got put back into the pool, close it.
        if conn:
            conn.close()

    def _validate_conn(self, conn):
        """
        Called right before a request is made, after the socket is created.
        """
        pass

    def _prepare_proxy(self, conn):
        # Nothing to do for HTTP connections.
        pass

    def _get_timeout(self, timeout):
        """Helper that always returns a :class:`urllib3.util.Timeout`"""
        if timeout is _Default:
            return self.timeout.clone()

        if isinstance(timeout, Timeout):
            return timeout.clone()
        else:
            # User passed us an int/float. This is for backwards compatibility,
            # can be removed later
            return Timeout.from_float(timeout)

    def _raise_timeout(self, err, url, timeout_value):
        """Is the error actually a timeout? Will raise a ReadTimeout or pass"""

        if isinstance(err, SocketTimeout):
            raise ReadTimeoutError(
                self, url, "Read timed out. (read timeout=%s)" % timeout_value
            )

        # See the above comment about EAGAIN in Python 3. In Python 2 we have
        # to specifically catch it and throw the timeout error
        if hasattr(err, "errno") and err.errno in _blocking_errnos:
            raise ReadTimeoutError(
                self, url, "Read timed out. (read timeout=%s)" % timeout_value
            )

        # Catch possible read timeouts thrown as SSL errors. If not the
        # case, rethrow the original. We need to do this because of:
        # http://bugs.python.org/issue10272
        if "timed out" in str(err) or "did not complete (read)" in str(
            err
        ):  # Python < 2.7.4
            raise ReadTimeoutError(
                self, url, "Read timed out. (read timeout=%s)" % timeout_value
            )

    def _make_request(
        self, conn, method, url, timeout=_Default, chunked=False, **httplib_request_kw
    ):
        """
        Perform a request on a given urllib connection object taken from our
        pool.

        :param conn:
            a connection from one of our connection pools

        :param timeout:
            Socket timeout in seconds for the request. This can be a
            float or integer, which will set the same timeout value for
            the socket connect and the socket read, or an instance of
            :class:`urllib3.util.Timeout`, which gives you more fine-grained
            control over your timeouts.
        """
        self.num_requests += 1

        timeout_obj = self._get_timeout(timeout)
        timeout_obj.start_connect()
        conn.timeout = timeout_obj.connect_timeout

        # Trigger any extra validation we need to do.
        try:
            self._validate_conn(conn)
        except (SocketTimeout, BaseSSLError) as e:
            # Py2 raises this as a BaseSSLError, Py3 raises it as socket timeout.
            self._raise_timeout(err=e, url=url, timeout_value=conn.timeout)
            raise

        # conn.request() calls http.client.*.request, not the method in
        # urllib3.request. It also calls makefile (recv) on the socket.
        try:
            if chunked:
                conn.request_chunked(method, url, **httplib_request_kw)
            else:
                conn.request(method, url, **httplib_request_kw)

        # We are swallowing BrokenPipeError (errno.EPIPE) since the server is
        # legitimately able to close the connection after sending a valid response.
        # With this behaviour, the received response is still readable.
        except BrokenPipeError:
            # Python 3
            pass
        except IOError as e:
            # Python 2 and macOS/Linux
            # EPIPE and ESHUTDOWN are BrokenPipeError on Python 2, and EPROTOTYPE is needed on macOS
            # https://erickt.github.io/blog/2014/11/19/adventures-in-debugging-a-potential-osx-kernel-bug/
            if e.errno not in {
                errno.EPIPE,
                errno.ESHUTDOWN,
                errno.EPROTOTYPE,
            }:
                raise

        # Reset the timeout for the recv() on the socket
        read_timeout = timeout_obj.read_timeout

        # App Engine doesn't have a sock attr
        if getattr(conn, "sock", None):
            # In Python 3 socket.py will catch EAGAIN and return None when you
            # try and read into the file pointer created by http.client, which
            # instead raises a BadStatusLine exception. Instead of catching
            # the exception and assuming all BadStatusLine exceptions are read
            # timeouts, check for a zero timeout before making the request.
            if read_timeout == 0:
                raise ReadTimeoutError(
                    self, url, "Read timed out. (read timeout=%s)" % read_timeout
                )
            if read_timeout is Timeout.DEFAULT_TIMEOUT:
                conn.sock.settimeout(socket.getdefaulttimeout())
            else:  # None or a value
                conn.sock.settimeout(read_timeout)

        # Receive the response from the server
        try:
            try:
                # Python 2.7, use buffering of HTTP responses
                httplib_response = conn.getresponse(buffering=True)
            except TypeError:
                # Python 3
                try:
                    httplib_response = conn.getresponse()
                except BaseException as e:
                    # Remove the TypeError from the exception chain in
                    # Python 3 (including for exceptions like SystemExit).
                    # Otherwise it looks like a bug in the code.
                    six.raise_from(e, None)
        except (SocketTimeout, BaseSSLError, SocketError) as e:
            self._raise_timeout(err=e, url=url, timeout_value=read_timeout)
            raise

        # AppEngine doesn't have a version attr.
        http_version = getattr(conn, "_http_vsn_str", "HTTP/?")
        log.debug(
            '%s://%s:%s "%s %s %s" %s %s',
            self.scheme,
            self.host,
            self.port,
            method,
            url,
            http_version,
            httplib_response.status,
            httplib_response.length,
        )

        try:
            assert_header_parsing(httplib_response.msg)
        except (HeaderParsingError, TypeError) as hpe:  # Platform-specific: Python 3
            log.warning(
                "Failed to parse headers (url=%s): %s",
                self._absolute_url(url),
                hpe,
                exc_info=True,
            )

        return httplib_response

    def _absolute_url(self, path):
        return Url(scheme=self.scheme, host=self.host, port=self.port, path=path).url

    def close(self):
        """
        Close all pooled connections and disable the pool.
        """
        if self.pool is None:
            return
        # Disable access to the pool
        old_pool, self.pool = self.pool, None

        try:
            while True:
                conn = old_pool.get(block=False)
                if conn:
                    conn.close()

        except queue.Empty:
            pass  # Done.

    def is_same_host(self, url):
        """
        Check if the given ``url`` is a member of the same host as this
        connection pool.
        """
        if url.startswith("/"):
            return True

        # TODO: Add optional support for socket.gethostbyname checking.
        scheme, host, port = get_host(url)
        if host is not None:
            host = _normalize_host(host, scheme=scheme)

        # Use explicit default port for comparison when none is given
        if self.port and not port:
            port = port_by_scheme.get(scheme)
        elif not self.port and port == port_by_scheme.get(scheme):
            port = None

        return (scheme, host, port) == (self.scheme, self.host, self.port)

    def urlopen(
        self,
        method,
        url,
        body=None,
        headers=None,
        retries=None,
        redirect=True,
        assert_same_host=True,
        timeout=_Default,
        pool_timeout=None,
        release_conn=None,
        chunked=False,
        body_pos=None,
        **response_kw
    ):
        """
        Get a connection from the pool and perform an HTTP request. This is the
        lowest level call for making a request, so you'll need to specify all
        the raw details.

        .. note::

           More commonly, it's appropriate to use a convenience method provided
           by :class:`.RequestMethods`, such as :meth:`request`.

        .. note::

           `release_conn` will only behave as expected if
           `preload_content=False` because we want to make
           `preload_content=False` the default behaviour someday soon without
           breaking backwards compatibility.

        :param method:
            HTTP request method (such as GET, POST, PUT, etc.)

        :param url:
            The URL to perform the request on.

        :param body:
            Data to send in the request body, either :class:`str`, :class:`bytes`,
            an iterable of :class:`str`/:class:`bytes`, or a file-like object.

        :param headers:
            Dictionary of custom headers to send, such as User-Agent,
            If-None-Match, etc. If None, pool headers are used. If provided,
            these headers completely replace any pool-specific headers.

        :param retries:
            Configure the number of retries to allow before raising a
            :class:`~urllib3.exceptions.MaxRetryError` exception.

            Pass ``None`` to retry until you receive a response. Pass a
            :class:`~urllib3.util.retry.Retry` object for fine-grained control
            over different types of retries.
            Pass an integer number to retry connection errors that many times,
            but no other types of errors. Pass zero to never retry.

            If ``False``, then retries are disabled and any exception is raised
            immediately. Also, instead of raising a MaxRetryError on redirects,
            the redirect response will be returned.

        :type retries: :class:`~urllib3.util.retry.Retry`, False, or an int.

        :param redirect:
            If True, automatically handle redirects (status codes 301, 302,
            303, 307, 308). Each redirect counts as a retry. Disabling retries
            will disable redirect, too.

        :param assert_same_host:
            If ``True``, will make sure that the host of the pool requests is
            consistent else will raise HostChangedError. When ``False``, you can
            use the pool on an HTTP proxy and request foreign hosts.

        :param timeout:
            If specified, overrides the default timeout for this one
            request. It may be a float (in seconds) or an instance of
            :class:`urllib3.util.Timeout`.

        :param pool_timeout:
            If set and the pool is set to block=True, then this method will
            block for ``pool_timeout`` seconds and raise EmptyPoolError if no
            connection is available within the time period.

        :param release_conn:
            If False, then the urlopen call will not release the connection
            back into the pool once a response is received (but will release if
            you read the entire contents of the response such as when
            `preload_content=True`). This is useful if you're not preloading
            the response's content immediately. You will need to call
            ``r.release_conn()`` on the response ``r`` to return the connection
            back into the pool. If None, it takes the value of
            ``response_kw.get('preload_content', True)``.

        :param chunked:
            If True, urllib3 will send the body using chunked transfer
            encoding. Otherwise, urllib3 will send the body using the standard
            content-length form. Defaults to False.

        :param int body_pos:
            Position to seek to in file-like body in the event of a retry or
            redirect. Typically this won't need to be set because urllib3 will
            auto-populate the value when needed.

        :param \\**response_kw:
            Additional parameters are passed to
            :meth:`urllib3.response.HTTPResponse.from_httplib`
        """

        parsed_url = parse_url(url)
        destination_scheme = parsed_url.scheme

        if headers is None:
            headers = self.headers

        if not isinstance(retries, Retry):
            retries = Retry.from_int(retries, redirect=redirect, default=self.retries)

        if release_conn is None:
            release_conn = response_kw.get("preload_content", True)

        # Check host
        if assert_same_host and not self.is_same_host(url):
            raise HostChangedError(self, url, retries)

        # Ensure that the URL we're connecting to is properly encoded
        if url.startswith("/"):
            url = six.ensure_str(_encode_target(url))
        else:
            url = six.ensure_str(parsed_url.url)

        conn = None

        # Track whether `conn` needs to be released before
        # returning/raising/recursing. Update this variable if necessary, and
        # leave `release_conn` constant throughout the function. That way, if
        # the function recurses, the original value of `release_conn` will be
        # passed down into the recursive call, and its value will be respected.
        #
        # See issue #651 [1] for details.
        #
        # [1] <https://github.com/urllib3/urllib3/issues/651>
        release_this_conn = release_conn

        http_tunnel_required = connection_requires_http_tunnel(
            self.proxy, self.proxy_config, destination_scheme
        )

        # Merge the proxy headers. Only done when not using HTTP CONNECT. We
        # have to copy the headers dict so we can safely change it without those
        # changes being reflected in anyone else's copy.
        if not http_tunnel_required:
            headers = headers.copy()
            headers.update(self.proxy_headers)

        # Must keep the exception bound to a separate variable or else Python 3
        # complains about UnboundLocalError.
        err = None

        # Keep track of whether we cleanly exited the except block. This
        # ensures we do proper cleanup in finally.
        clean_exit = False

        # Rewind body position, if needed. Record current position
        # for future rewinds in the event of a redirect/retry.
        body_pos = set_file_position(body, body_pos)

        try:
            # Request a connection from the queue.
            timeout_obj = self._get_timeout(timeout)
            conn = self._get_conn(timeout=pool_timeout)

            conn.timeout = timeout_obj.connect_timeout

            is_new_proxy_conn = self.proxy is not None and not getattr(
                conn, "sock", None
            )
            if is_new_proxy_conn and http_tunnel_required:
                self._prepare_proxy(conn)

            # Make the request on the httplib connection object.
            httplib_response = self._make_request(
                conn,
                method,
                url,
                timeout=timeout_obj,
                body=body,
                headers=headers,
                chunked=chunked,
            )

            # If we're going to release the connection in ``finally:``, then
            # the response doesn't need to know about the connection. Otherwise
            # it will also try to release it and we'll have a double-release
            # mess.
            response_conn = conn if not release_conn else None

            # Pass method to Response for length checking
            response_kw["request_method"] = method

            # Import httplib's response into our own wrapper object
            response = self.ResponseCls.from_httplib(
                httplib_response,
                pool=self,
                connection=response_conn,
                retries=retries,
                **response_kw
            )

            # Everything went great!
            clean_exit = True

        except EmptyPoolError:
            # Didn't get a connection from the pool, no need to clean up
            clean_exit = True
            release_this_conn = False
            raise

        except (
            TimeoutError,
            HTTPException,
            SocketError,
            ProtocolError,
            BaseSSLError,
            SSLError,
            CertificateError,
        ) as e:
            # Discard the connection for these exceptions. It will be
            # replaced during the next _get_conn() call.
            clean_exit = False
            if isinstance(e, (BaseSSLError, CertificateError)):
                e = SSLError(e)
            elif isinstance(e, (SocketError, NewConnectionError)) and self.proxy:
                e = ProxyError("Cannot connect to proxy.", e)
            elif isinstance(e, (SocketError, HTTPException)):
                e = ProtocolError("Connection aborted.", e)

            retries = retries.increment(
                method, url, error=e, _pool=self, _stacktrace=sys.exc_info()[2]
            )
            retries.sleep()

            # Keep track of the error for the retry warning.
            err = e

        finally:
            if not clean_exit:
                # We hit some kind of exception, handled or otherwise. We need
                # to throw the connection away unless explicitly told not to.
                # Close the connection, set the variable to None, and make sure
                # we put the None back in the pool to avoid leaking it.
                conn = conn and conn.close()
                release_this_conn = True

            if release_this_conn:
                # Put the connection back to be reused. If the connection is
                # expired then it will be None, which will get replaced with a
                # fresh connection during _get_conn.
                self._put_conn(conn)

        if not conn:
            # Try again
            log.warning(
                "Retrying (%r) after connection broken by '%r': %s", retries, err, url
            )
            return self.urlopen(
                method,
                url,
                body,
                headers,
                retries,
                redirect,
                assert_same_host,
                timeout=timeout,
                pool_timeout=pool_timeout,
                release_conn=release_conn,
                chunked=chunked,
                body_pos=body_pos,
                **response_kw
            )

        # Handle redirect?
        redirect_location = redirect and response.get_redirect_location()
        if redirect_location:
            if response.status == 303:
                method = "GET"

            try:
                retries = retries.increment(method, url, response=response, _pool=self)
            except MaxRetryError:
                if retries.raise_on_redirect:
                    response.drain_conn()
                    raise
                return response

            response.drain_conn()
            retries.sleep_for_retry(response)
            log.debug("Redirecting %s -> %s", url, redirect_location)
            return self.urlopen(
                method,
                redirect_location,
                body,
                headers,
                retries=retries,
                redirect=redirect,
                assert_same_host=assert_same_host,
                timeout=timeout,
                pool_timeout=pool_timeout,
                release_conn=release_conn,
                chunked=chunked,
                body_pos=body_pos,
                **response_kw
            )

        # Check if we should retry the HTTP response.
        has_retry_after = bool(response.getheader("Retry-After"))
        if retries.is_retry(method, response.status, has_retry_after):
            try:
                retries = retries.increment(method, url, response=response, _pool=self)
            except MaxRetryError:
                if retries.raise_on_status:
                    response.drain_conn()
                    raise
                return response

            response.drain_conn()
            retries.sleep(response)
            log.debug("Retry: %s", url)
            return self.urlopen(
                method,
                url,
                body,
                headers,
                retries=retries,
                redirect=redirect,
                assert_same_host=assert_same_host,
                timeout=timeout,
                pool_timeout=pool_timeout,
                release_conn=release_conn,
                chunked=chunked,
                body_pos=body_pos,
                **response_kw
            )

        return response

class HTTPResponse(io.IOBase):
    """
    HTTP Response container.

    Backwards-compatible with :class:`http.client.HTTPResponse` but the response ``body`` is
    loaded and decoded on-demand when the ``data`` property is accessed.  This
    class is also compatible with the Python standard library's :mod:`io`
    module, and can hence be treated as a readable object in the context of that
    framework.

    Extra parameters for behaviour not present in :class:`http.client.HTTPResponse`:

    :param preload_content:
        If True, the response's body will be preloaded during construction.

    :param decode_content:
        If True, will attempt to decode the body based on the
        'content-encoding' header.

    :param original_response:
        When this HTTPResponse wrapper is generated from an :class:`http.client.HTTPResponse`
        object, it's convenient to include the original for debug purposes. It's
        otherwise unused.

    :param retries:
        The retries contains the last :class:`~urllib3.util.retry.Retry` that
        was used during the request.

    :param enforce_content_length:
        Enforce content length checking. Body returned by server must match
        value of Content-Length header, if present. Otherwise, raise error.
    """

    CONTENT_DECODERS = ["gzip", "deflate"]
    if brotli is not None:
        CONTENT_DECODERS += ["br"]
    REDIRECT_STATUSES = [301, 302, 303, 307, 308]

    def __init__(
        self,
        body="",
        headers=None,
        status=0,
        version=0,
        reason=None,
        strict=0,
        preload_content=True,
        decode_content=True,
        original_response=None,
        pool=None,
        connection=None,
        msg=None,
        retries=None,
        enforce_content_length=False,
        request_method=None,
        request_url=None,
        auto_close=True,
    ):

        if isinstance(headers, HTTPHeaderDict):
            self.headers = headers
        else:
            self.headers = HTTPHeaderDict(headers)
        self.status = status
        self.version = version
        self.reason = reason
        self.strict = strict
        self.decode_content = decode_content
        self.retries = retries
        self.enforce_content_length = enforce_content_length
        self.auto_close = auto_close

        self._decoder = None
        self._body = None
        self._fp = None
        self._original_response = original_response
        self._fp_bytes_read = 0
        self.msg = msg
        self._request_url = request_url

        if body and isinstance(body, (six.string_types, bytes)):
            self._body = body

        self._pool = pool
        self._connection = connection

        if hasattr(body, "read"):
            self._fp = body

        # Are we using the chunked-style of transfer encoding?
        self.chunked = False
        self.chunk_left = None
        tr_enc = self.headers.get("transfer-encoding", "").lower()
        # Don't incur the penalty of creating a list and then discarding it
        encodings = (enc.strip() for enc in tr_enc.split(","))
        if "chunked" in encodings:
            self.chunked = True

        # Determine length of response
        self.length_remaining = self._init_length(request_method)

        # If requested, preload the body.
        if preload_content and not self._body:
            self._body = self.read(decode_content=decode_content)

    def get_redirect_location(self):
        """
        Should we redirect and where to?

        :returns: Truthy redirect location string if we got a redirect status
            code and valid location. ``None`` if redirect status and no
            location. ``False`` if not a redirect status code.
        """
        if self.status in self.REDIRECT_STATUSES:
            return self.headers.get("location")

        return False

    def release_conn(self):
        if not self._pool or not self._connection:
            return

        self._pool._put_conn(self._connection)
        self._connection = None

    def drain_conn(self):
        """
        Read and discard any remaining HTTP response data in the response connection.

        Unread data in the HTTPResponse connection blocks the connection from being released back to the pool.
        """
        try:
            self.read()
        except (HTTPError, SocketError, BaseSSLError, HTTPException):
            pass

    @property
    def data(self):
        # For backwards-compat with earlier urllib3 0.4 and earlier.
        if self._body:
            return self._body

        if self._fp:
            return self.read(cache_content=True)

    @property
    def connection(self):
        return self._connection

    def isclosed(self):
        return is_fp_closed(self._fp)

    def tell(self):
        """
        Obtain the number of bytes pulled over the wire so far. May differ from
        the amount of content returned by :meth:``urllib3.response.HTTPResponse.read``
        if bytes are encoded on the wire (e.g, compressed).
        """
        return self._fp_bytes_read

    def _init_length(self, request_method):
        """
        Set initial length value for Response content if available.
        """
        length = self.headers.get("content-length")

        if length is not None:
            if self.chunked:
                # This Response will fail with an IncompleteRead if it can't be
                # received as chunked. This method falls back to attempt reading
                # the response before raising an exception.
                log.warning(
                    "Received response with both Content-Length and "
                    "Transfer-Encoding set. This is expressly forbidden "
                    "by RFC 7230 sec 3.3.2. Ignoring Content-Length and "
                    "attempting to process response as Transfer-Encoding: "
                    "chunked."
                )
                return None

            try:
                # RFC 7230 section 3.3.2 specifies multiple content lengths can
                # be sent in a single Content-Length header
                # (e.g. Content-Length: 42, 42). This line ensures the values
                # are all valid ints and that as long as the `set` length is 1,
                # all values are the same. Otherwise, the header is invalid.
                lengths = set([int(val) for val in length.split(",")])
                if len(lengths) > 1:
                    raise InvalidHeader(
                        "Content-Length contained multiple "
                        "unmatching values (%s)" % length
                    )
                length = lengths.pop()
            except ValueError:
                length = None
            else:
                if length < 0:
                    length = None

        # Convert status to int for comparison
        # In some cases, httplib returns a status of "_UNKNOWN"
        try:
            status = int(self.status)
        except ValueError:
            status = 0

        # Check for responses that shouldn't include a body
        if status in (204, 304) or 100 <= status < 200 or request_method == "HEAD":
            length = 0

        return length

    def _init_decoder(self):
        """
        Set-up the _decoder attribute if necessary.
        """
        # Note: content-encoding value should be case-insensitive, per RFC 7230
        # Section 3.2
        content_encoding = self.headers.get("content-encoding", "").lower()
        if self._decoder is None:
            if content_encoding in self.CONTENT_DECODERS:
                self._decoder = _get_decoder(content_encoding)
            elif "," in content_encoding:
                encodings = [
                    e.strip()
                    for e in content_encoding.split(",")
                    if e.strip() in self.CONTENT_DECODERS
                ]
                if len(encodings):
                    self._decoder = _get_decoder(content_encoding)

    DECODER_ERROR_CLASSES = (IOError, zlib.error)
    if brotli is not None:
        DECODER_ERROR_CLASSES += (brotli.error,)

    def _decode(self, data, decode_content, flush_decoder):
        """
        Decode the data passed in and potentially flush the decoder.
        """
        if not decode_content:
            return data

        try:
            if self._decoder:
                data = self._decoder.decompress(data)
        except self.DECODER_ERROR_CLASSES as e:
            content_encoding = self.headers.get("content-encoding", "").lower()
            raise DecodeError(
                "Received response with content-encoding: %s, but "
                "failed to decode it." % content_encoding,
                e,
            )
        if flush_decoder:
            data += self._flush_decoder()

        return data

    def _flush_decoder(self):
        """
        Flushes the decoder. Should only be called if the decoder is actually
        being used.
        """
        if self._decoder:
            buf = self._decoder.decompress(b"")
            return buf + self._decoder.flush()

        return b""

    @contextmanager
    def _error_catcher(self):
        """
        Catch low-level python exceptions, instead re-raising urllib3
        variants, so that low-level exceptions are not leaked in the
        high-level api.

        On exit, release the connection back to the pool.
        """
        clean_exit = False

        try:
            try:
                yield

            except SocketTimeout:
                # FIXME: Ideally we'd like to include the url in the ReadTimeoutError but
                # there is yet no clean way to get at it from this context.
                raise ReadTimeoutError(self._pool, None, "Read timed out.")

            except BaseSSLError as e:
                # FIXME: Is there a better way to differentiate between SSLErrors?
                if "read operation timed out" not in str(e):
                    # SSL errors related to framing/MAC get wrapped and reraised here
                    raise SSLError(e)

                raise ReadTimeoutError(self._pool, None, "Read timed out.")

            except (HTTPException, SocketError) as e:
                # This includes IncompleteRead.
                raise ProtocolError("Connection broken: %r" % e, e)

            # If no exception is thrown, we should avoid cleaning up
            # unnecessarily.
            clean_exit = True
        finally:
            # If we didn't terminate cleanly, we need to throw away our
            # connection.
            if not clean_exit:
                # The response may not be closed but we're not going to use it
                # anymore so close it now to ensure that the connection is
                # released back to the pool.
                if self._original_response:
                    self._original_response.close()

                # Closing the response may not actually be sufficient to close
                # everything, so if we have a hold of the connection close that
                # too.
                if self._connection:
                    self._connection.close()

            # If we hold the original response but it's closed now, we should
            # return the connection back to the pool.
            if self._original_response and self._original_response.isclosed():
                self.release_conn()

    def read(self, amt=None, decode_content=None, cache_content=False):
        """
        Similar to :meth:`http.client.HTTPResponse.read`, but with two additional
        parameters: ``decode_content`` and ``cache_content``.

        :param amt:
            How much of the content to read. If specified, caching is skipped
            because it doesn't make sense to cache partial content as the full
            response.

        :param decode_content:
            If True, will attempt to decode the body based on the
            'content-encoding' header.

        :param cache_content:
            If True, will save the returned data such that the same result is
            returned despite of the state of the underlying file object. This
            is useful if you want the ``.data`` property to continue working
            after having ``.read()`` the file object. (Overridden if ``amt`` is
            set.)
        """
        self._init_decoder()
        if decode_content is None:
            decode_content = self.decode_content

        if self._fp is None:
            return

        flush_decoder = False
        fp_closed = getattr(self._fp, "closed", False)

        with self._error_catcher():
            if amt is None:
                # cStringIO doesn't like amt=None
                data = self._fp.read() if not fp_closed else b""
                flush_decoder = True
            else:
                cache_content = False
                data = self._fp.read(amt) if not fp_closed else b""
                if (
                    amt != 0 and not data
                ):  # Platform-specific: Buggy versions of Python.
                    # Close the connection when no data is returned
                    #
                    # This is redundant to what httplib/http.client _should_
                    # already do.  However, versions of python released before
                    # December 15, 2012 (http://bugs.python.org/issue16298) do
                    # not properly close the connection in all cases. There is
                    # no harm in redundantly calling close.
                    self._fp.close()
                    flush_decoder = True
                    if self.enforce_content_length and self.length_remaining not in (
                        0,
                        None,
                    ):
                        # This is an edge case that httplib failed to cover due
                        # to concerns of backward compatibility. We're
                        # addressing it here to make sure IncompleteRead is
                        # raised during streaming, so all calls with incorrect
                        # Content-Length are caught.
                        raise IncompleteRead(self._fp_bytes_read, self.length_remaining)

        if data:
            self._fp_bytes_read += len(data)
            if self.length_remaining is not None:
                self.length_remaining -= len(data)

            data = self._decode(data, decode_content, flush_decoder)

            if cache_content:
                self._body = data

        return data

    def stream(self, amt=2 ** 16, decode_content=None):
        """
        A generator wrapper for the read() method. A call will block until
        ``amt`` bytes have been read from the connection or until the
        connection is closed.

        :param amt:
            How much of the content to read. The generator will return up to
            much data per iteration, but may return less. This is particularly
            likely when using compressed data. However, the empty string will
            never be returned.

        :param decode_content:
            If True, will attempt to decode the body based on the
            'content-encoding' header.
        """
        if self.chunked and self.supports_chunked_reads():
            for line in self.read_chunked(amt, decode_content=decode_content):
                yield line
        else:
            while not is_fp_closed(self._fp):
                data = self.read(amt=amt, decode_content=decode_content)

                if data:
                    yield data

    @classmethod
    def from_httplib(ResponseCls, r, **response_kw):
        """
        Given an :class:`http.client.HTTPResponse` instance ``r``, return a
        corresponding :class:`urllib3.response.HTTPResponse` object.

        Remaining parameters are passed to the HTTPResponse constructor, along
        with ``original_response=r``.
        """
        headers = r.msg

        if not isinstance(headers, HTTPHeaderDict):
            if six.PY2:
                # Python 2.7
                headers = HTTPHeaderDict.from_httplib(headers)
            else:
                headers = HTTPHeaderDict(headers.items())

        # HTTPResponse objects in Python 3 don't have a .strict attribute
        strict = getattr(r, "strict", 0)
        resp = ResponseCls(
            body=r,
            headers=headers,
            status=r.status,
            version=r.version,
            reason=r.reason,
            strict=strict,
            original_response=r,
            **response_kw
        )
        return resp

    # Backwards-compatibility methods for http.client.HTTPResponse
    def getheaders(self):
        return self.headers

    def getheader(self, name, default=None):
        return self.headers.get(name, default)

    # Backwards compatibility for http.cookiejar
    def info(self):
        return self.headers

    # Overrides from io.IOBase
    def close(self):
        if not self.closed:
            self._fp.close()

        if self._connection:
            self._connection.close()

        if not self.auto_close:
            io.IOBase.close(self)

    @property
    def closed(self):
        if not self.auto_close:
            return io.IOBase.closed.__get__(self)
        elif self._fp is None:
            return True
        elif hasattr(self._fp, "isclosed"):
            return self._fp.isclosed()
        elif hasattr(self._fp, "closed"):
            return self._fp.closed
        else:
            return True

    def fileno(self):
        if self._fp is None:
            raise IOError("HTTPResponse has no file to get a fileno from")
        elif hasattr(self._fp, "fileno"):
            return self._fp.fileno()
        else:
            raise IOError(
                "The file-like object this HTTPResponse is wrapped "
                "around has no file descriptor"
            )

    def flush(self):
        if (
            self._fp is not None
            and hasattr(self._fp, "flush")
            and not getattr(self._fp, "closed", False)
        ):
            return self._fp.flush()

    def readable(self):
        # This method is required for `io` module compatibility.
        return True

    def readinto(self, b):
        # This method is required for `io` module compatibility.
        temp = self.read(len(b))
        if len(temp) == 0:
            return 0
        else:
            b[: len(temp)] = temp
            return len(temp)

    def supports_chunked_reads(self):
        """
        Checks if the underlying file-like object looks like a
        :class:`http.client.HTTPResponse` object. We do this by testing for
        the fp attribute. If it is present we assume it returns raw chunks as
        processed by read_chunked().
        """
        return hasattr(self._fp, "fp")

    def _update_chunk_length(self):
        # First, we'll figure out length of a chunk and then
        # we'll try to read it from socket.
        if self.chunk_left is not None:
            return
        line = self._fp.fp.readline()
        line = line.split(b";", 1)[0]
        try:
            self.chunk_left = int(line, 16)
        except ValueError:
            # Invalid chunked protocol response, abort.
            self.close()
            raise InvalidChunkLength(self, line)

    def _handle_chunk(self, amt):
        returned_chunk = None
        if amt is None:
            chunk = self._fp._safe_read(self.chunk_left)
            returned_chunk = chunk
            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.
            self.chunk_left = None
        elif amt < self.chunk_left:
            value = self._fp._safe_read(amt)
            self.chunk_left = self.chunk_left - amt
            returned_chunk = value
        elif amt == self.chunk_left:
            value = self._fp._safe_read(amt)
            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.
            self.chunk_left = None
            returned_chunk = value
        else:  # amt > self.chunk_left
            returned_chunk = self._fp._safe_read(self.chunk_left)
            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.
            self.chunk_left = None
        return returned_chunk

    def read_chunked(self, amt=None, decode_content=None):
        """
        Similar to :meth:`HTTPResponse.read`, but with an additional
        parameter: ``decode_content``.

        :param amt:
            How much of the content to read. If specified, caching is skipped
            because it doesn't make sense to cache partial content as the full
            response.

        :param decode_content:
            If True, will attempt to decode the body based on the
            'content-encoding' header.
        """
        self._init_decoder()
        # FIXME: Rewrite this method and make it a class with a better structured logic.
        if not self.chunked:
            raise ResponseNotChunked(
                "Response is not chunked. "
                "Header 'transfer-encoding: chunked' is missing."
            )
        if not self.supports_chunked_reads():
            raise BodyNotHttplibCompatible(
                "Body should be http.client.HTTPResponse like. "
                "It should have have an fp attribute which returns raw chunks."
            )

        with self._error_catcher():
            # Don't bother reading the body of a HEAD request.
            if self._original_response and is_response_to_head(self._original_response):
                self._original_response.close()
                return

            # If a response is already read and closed
            # then return immediately.
            if self._fp.fp is None:
                return

            while True:
                self._update_chunk_length()
                if self.chunk_left == 0:
                    break
                chunk = self._handle_chunk(amt)
                decoded = self._decode(
                    chunk, decode_content=decode_content, flush_decoder=False
                )
                if decoded:
                    yield decoded

            if decode_content:
                # On CPython and PyPy, we should never need to flush the
                # decoder. However, on Jython we *might* need to, so
                # lets defensively do it anyway.
                decoded = self._flush_decoder()
                if decoded:  # Platform-specific: Jython.
                    yield decoded

            # Chunk content ends with \r\n: discard it.
            while True:
                line = self._fp.fp.readline()
                if not line:
                    # Some sites may not end with '\r\n'.
                    break
                if line == b"\r\n":
                    break

            # We read everything; close the "file".
            if self._original_response:
                self._original_response.close()

    def geturl(self):
        """
        Returns the URL that was the source of this response.
        If the request that generated this response redirected, this method
        will return the final redirect location.
        """
        if self.retries is not None and len(self.retries.history):
            return self.retries.history[-1].redirect_location
        else:
            return self._request_url

    def __iter__(self):
        buffer = []
        for chunk in self.stream(decode_content=True):
            if b"\n" in chunk:
                chunk = chunk.split(b"\n")
                yield b"".join(buffer) + chunk[0] + b"\n"
                for x in chunk[1:-1]:
                    yield x + b"\n"
                if chunk[-1]:
                    buffer = [chunk[-1]]
                else:
                    buffer = []
            else:
                buffer.append(chunk)
        if buffer:
            yield b"".join(buffer)