anonymousland-synapse/synapse/rest/media/v1/_base.py

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