480 lines
15 KiB
Python
480 lines
15 KiB
Python
# Copyright 2014-2016 OpenMarket Ltd
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# Copyright 2019-2021 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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import os
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import urllib
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from abc import ABC, abstractmethod
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from types import TracebackType
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from typing import Awaitable, Dict, Generator, List, Optional, Tuple, Type
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import attr
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from twisted.internet.interfaces import IConsumer
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from twisted.protocols.basic import FileSender
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from twisted.web.server import Request
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from synapse.api.errors import Codes, SynapseError, cs_error
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from synapse.http.server import finish_request, respond_with_json
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from synapse.http.site import SynapseRequest
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from synapse.logging.context import make_deferred_yieldable
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from synapse.util.stringutils import is_ascii, parse_and_validate_server_name
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logger = logging.getLogger(__name__)
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# list all text content types that will have the charset default to UTF-8 when
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# none is given
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TEXT_CONTENT_TYPES = [
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"text/css",
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"text/csv",
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"text/html",
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"text/calendar",
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"text/plain",
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"text/javascript",
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"application/json",
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"application/ld+json",
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"application/rtf",
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"image/svg+xml",
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"text/xml",
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]
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def parse_media_id(request: Request) -> Tuple[str, str, Optional[str]]:
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"""Parses the server name, media ID and optional file name from the request URI
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Also performs some rough validation on the server name.
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Args:
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request: The `Request`.
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Returns:
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A tuple containing the parsed server name, media ID and optional file name.
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Raises:
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SynapseError(404): if parsing or validation fail for any reason
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"""
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try:
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# The type on postpath seems incorrect in Twisted 21.2.0.
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postpath: List[bytes] = request.postpath # type: ignore
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assert postpath
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# This allows users to append e.g. /test.png to the URL. Useful for
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# clients that parse the URL to see content type.
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server_name_bytes, media_id_bytes = postpath[:2]
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server_name = server_name_bytes.decode("utf-8")
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media_id = media_id_bytes.decode("utf8")
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# Validate the server name, raising if invalid
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parse_and_validate_server_name(server_name)
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file_name = None
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if len(postpath) > 2:
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try:
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file_name = urllib.parse.unquote(postpath[-1].decode("utf-8"))
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except UnicodeDecodeError:
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pass
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return server_name, media_id, file_name
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except Exception:
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raise SynapseError(
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404, "Invalid media id token %r" % (request.postpath,), Codes.UNKNOWN
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)
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def respond_404(request: SynapseRequest) -> None:
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respond_with_json(
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request,
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404,
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cs_error("Not found %r" % (request.postpath,), code=Codes.NOT_FOUND),
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send_cors=True,
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)
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async def respond_with_file(
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request: SynapseRequest,
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media_type: str,
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file_path: str,
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file_size: Optional[int] = None,
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upload_name: Optional[str] = None,
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) -> None:
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logger.debug("Responding with %r", file_path)
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if os.path.isfile(file_path):
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if file_size is None:
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stat = os.stat(file_path)
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file_size = stat.st_size
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add_file_headers(request, media_type, file_size, upload_name)
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with open(file_path, "rb") as f:
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await make_deferred_yieldable(FileSender().beginFileTransfer(f, request))
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finish_request(request)
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else:
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respond_404(request)
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def add_file_headers(
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request: Request,
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media_type: str,
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file_size: Optional[int],
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upload_name: Optional[str],
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) -> None:
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"""Adds the correct response headers in preparation for responding with the
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media.
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Args:
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request
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media_type: The media/content type.
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file_size: Size in bytes of the media, if known.
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upload_name: The name of the requested file, if any.
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"""
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def _quote(x: str) -> str:
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return urllib.parse.quote(x.encode("utf-8"))
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# Default to a UTF-8 charset for text content types.
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# ex, uses UTF-8 for 'text/css' but not 'text/css; charset=UTF-16'
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if media_type.lower() in TEXT_CONTENT_TYPES:
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content_type = media_type + "; charset=UTF-8"
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else:
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content_type = media_type
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request.setHeader(b"Content-Type", content_type.encode("UTF-8"))
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if upload_name:
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# RFC6266 section 4.1 [1] defines both `filename` and `filename*`.
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#
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# `filename` is defined to be a `value`, which is defined by RFC2616
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# section 3.6 [2] to be a `token` or a `quoted-string`, where a `token`
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# is (essentially) a single US-ASCII word, and a `quoted-string` is a
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# US-ASCII string surrounded by double-quotes, using backslash as an
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# escape character. Note that %-encoding is *not* permitted.
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#
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# `filename*` is defined to be an `ext-value`, which is defined in
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# RFC5987 section 3.2.1 [3] to be `charset "'" [ language ] "'" value-chars`,
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# where `value-chars` is essentially a %-encoded string in the given charset.
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#
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# [1]: https://tools.ietf.org/html/rfc6266#section-4.1
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# [2]: https://tools.ietf.org/html/rfc2616#section-3.6
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# [3]: https://tools.ietf.org/html/rfc5987#section-3.2.1
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# We avoid the quoted-string version of `filename`, because (a) synapse didn't
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# correctly interpret those as of 0.99.2 and (b) they are a bit of a pain and we
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# may as well just do the filename* version.
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if _can_encode_filename_as_token(upload_name):
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disposition = "inline; filename=%s" % (upload_name,)
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else:
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disposition = "inline; filename*=utf-8''%s" % (_quote(upload_name),)
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request.setHeader(b"Content-Disposition", disposition.encode("ascii"))
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# cache for at least a day.
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# XXX: we might want to turn this off for data we don't want to
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# recommend caching as it's sensitive or private - or at least
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# select private. don't bother setting Expires as all our
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# clients are smart enough to be happy with Cache-Control
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request.setHeader(b"Cache-Control", b"public,max-age=86400,s-maxage=86400")
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if file_size is not None:
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request.setHeader(b"Content-Length", b"%d" % (file_size,))
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# Tell web crawlers to not index, archive, or follow links in media. This
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# should help to prevent things in the media repo from showing up in web
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# search results.
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request.setHeader(b"X-Robots-Tag", "noindex, nofollow, noarchive, noimageindex")
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# separators as defined in RFC2616. SP and HT are handled separately.
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# see _can_encode_filename_as_token.
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_FILENAME_SEPARATOR_CHARS = {
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"(",
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")",
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"<",
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">",
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"@",
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",",
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";",
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":",
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"\\",
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'"',
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"/",
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"[",
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"]",
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"?",
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"=",
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"{",
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"}",
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}
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def _can_encode_filename_as_token(x: str) -> bool:
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for c in x:
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# from RFC2616:
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#
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# token = 1*<any CHAR except CTLs or separators>
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#
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# separators = "(" | ")" | "<" | ">" | "@"
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# | "," | ";" | ":" | "\" | <">
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# | "/" | "[" | "]" | "?" | "="
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# | "{" | "}" | SP | HT
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#
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# CHAR = <any US-ASCII character (octets 0 - 127)>
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#
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# CTL = <any US-ASCII control character
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# (octets 0 - 31) and DEL (127)>
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#
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if ord(c) >= 127 or ord(c) <= 32 or c in _FILENAME_SEPARATOR_CHARS:
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return False
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return True
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async def respond_with_responder(
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request: SynapseRequest,
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responder: "Optional[Responder]",
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media_type: str,
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file_size: Optional[int],
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upload_name: Optional[str] = None,
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) -> None:
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"""Responds to the request with given responder. If responder is None then
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returns 404.
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Args:
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request
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responder
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media_type: The media/content type.
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file_size: Size in bytes of the media. If not known it should be None
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upload_name: The name of the requested file, if any.
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"""
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if not responder:
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respond_404(request)
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return
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# If we have a responder we *must* use it as a context manager.
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with responder:
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if request._disconnected:
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logger.warning(
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"Not sending response to request %s, already disconnected.", request
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)
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return
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logger.debug("Responding to media request with responder %s", responder)
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add_file_headers(request, media_type, file_size, upload_name)
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try:
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await responder.write_to_consumer(request)
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except Exception as e:
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# The majority of the time this will be due to the client having gone
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# away. Unfortunately, Twisted simply throws a generic exception at us
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# in that case.
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logger.warning("Failed to write to consumer: %s %s", type(e), e)
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# Unregister the producer, if it has one, so Twisted doesn't complain
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if request.producer:
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request.unregisterProducer()
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finish_request(request)
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class Responder(ABC):
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"""Represents a response that can be streamed to the requester.
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Responder is a context manager which *must* be used, so that any resources
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held can be cleaned up.
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"""
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@abstractmethod
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def write_to_consumer(self, consumer: IConsumer) -> Awaitable:
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"""Stream response into consumer
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Args:
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consumer: The consumer to stream into.
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Returns:
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Resolves once the response has finished being written
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"""
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raise NotImplementedError()
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def __enter__(self) -> None: # noqa: B027
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pass
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def __exit__( # noqa: B027
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> None:
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pass
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@attr.s(slots=True, frozen=True, auto_attribs=True)
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class ThumbnailInfo:
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"""Details about a generated thumbnail."""
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width: int
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height: int
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method: str
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# Content type of thumbnail, e.g. image/png
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type: str
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# The size of the media file, in bytes.
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length: Optional[int] = None
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@attr.s(slots=True, frozen=True, auto_attribs=True)
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class FileInfo:
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"""Details about a requested/uploaded file."""
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# The server name where the media originated from, or None if local.
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server_name: Optional[str]
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# The local ID of the file. For local files this is the same as the media_id
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file_id: str
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# If the file is for the url preview cache
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url_cache: bool = False
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# Whether the file is a thumbnail or not.
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thumbnail: Optional[ThumbnailInfo] = None
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# The below properties exist to maintain compatibility with third-party modules.
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@property
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def thumbnail_width(self) -> Optional[int]:
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if not self.thumbnail:
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return None
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return self.thumbnail.width
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@property
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def thumbnail_height(self) -> Optional[int]:
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if not self.thumbnail:
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return None
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return self.thumbnail.height
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@property
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def thumbnail_method(self) -> Optional[str]:
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if not self.thumbnail:
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return None
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return self.thumbnail.method
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@property
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def thumbnail_type(self) -> Optional[str]:
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if not self.thumbnail:
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return None
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return self.thumbnail.type
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@property
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def thumbnail_length(self) -> Optional[int]:
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if not self.thumbnail:
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return None
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return self.thumbnail.length
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def get_filename_from_headers(headers: Dict[bytes, List[bytes]]) -> Optional[str]:
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"""
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Get the filename of the downloaded file by inspecting the
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Content-Disposition HTTP header.
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Args:
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headers: The HTTP request headers.
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Returns:
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The filename, or None.
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"""
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content_disposition = headers.get(b"Content-Disposition", [b""])
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# No header, bail out.
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if not content_disposition[0]:
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return None
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_, params = _parse_header(content_disposition[0])
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upload_name = None
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# First check if there is a valid UTF-8 filename
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upload_name_utf8 = params.get(b"filename*", None)
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if upload_name_utf8:
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if upload_name_utf8.lower().startswith(b"utf-8''"):
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upload_name_utf8 = upload_name_utf8[7:]
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# We have a filename*= section. This MUST be ASCII, and any UTF-8
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# bytes are %-quoted.
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try:
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# Once it is decoded, we can then unquote the %-encoded
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# parts strictly into a unicode string.
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upload_name = urllib.parse.unquote(
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upload_name_utf8.decode("ascii"), errors="strict"
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)
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except UnicodeDecodeError:
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# Incorrect UTF-8.
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pass
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# If there isn't check for an ascii name.
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if not upload_name:
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upload_name_ascii = params.get(b"filename", None)
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if upload_name_ascii and is_ascii(upload_name_ascii):
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upload_name = upload_name_ascii.decode("ascii")
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# This may be None here, indicating we did not find a matching name.
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return upload_name
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def _parse_header(line: bytes) -> Tuple[bytes, Dict[bytes, bytes]]:
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"""Parse a Content-type like header.
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Cargo-culted from `cgi`, but works on bytes rather than strings.
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Args:
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line: header to be parsed
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Returns:
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The main content-type, followed by the parameter dictionary
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"""
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parts = _parseparam(b";" + line)
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key = next(parts)
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pdict = {}
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for p in parts:
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i = p.find(b"=")
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if i >= 0:
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name = p[:i].strip().lower()
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value = p[i + 1 :].strip()
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# strip double-quotes
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if len(value) >= 2 and value[0:1] == value[-1:] == b'"':
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value = value[1:-1]
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value = value.replace(b"\\\\", b"\\").replace(b'\\"', b'"')
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pdict[name] = value
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return key, pdict
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def _parseparam(s: bytes) -> Generator[bytes, None, None]:
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"""Generator which splits the input on ;, respecting double-quoted sequences
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Cargo-culted from `cgi`, but works on bytes rather than strings.
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Args:
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s: header to be parsed
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Returns:
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The split input
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"""
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while s[:1] == b";":
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s = s[1:]
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# look for the next ;
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end = s.find(b";")
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# if there is an odd number of " marks between here and the next ;, skip to the
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# next ; instead
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while end > 0 and (s.count(b'"', 0, end) - s.count(b'\\"', 0, end)) % 2:
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end = s.find(b";", end + 1)
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if end < 0:
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end = len(s)
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f = s[:end]
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yield f.strip()
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s = s[end:]
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