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Diffstat (limited to 'synapse/media/_base.py')
| -rw-r--r-- | synapse/media/_base.py | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/synapse/media/_base.py b/synapse/media/_base.py new file mode 100644 index 0000000000..ef8334ae25 --- /dev/null +++ b/synapse/media/_base.py @@ -0,0 +1,479 @@ +# 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. + +import logging +import os +import urllib +from abc import ABC, abstractmethod +from types import TracebackType +from typing import Awaitable, Dict, Generator, List, Optional, Tuple, Type + +import attr + +from twisted.internet.interfaces import IConsumer +from twisted.protocols.basic import FileSender +from twisted.web.server import Request + +from synapse.api.errors import Codes, SynapseError, cs_error +from synapse.http.server import finish_request, respond_with_json +from synapse.http.site import SynapseRequest +from synapse.logging.context import make_deferred_yieldable +from synapse.util.stringutils import is_ascii, parse_and_validate_server_name + +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]]: + """Parses the server name, media ID and optional file name from the request URI + + Also performs some rough validation on the server name. + + Args: + request: The `Request`. + + Returns: + A tuple containing the parsed server name, media ID and optional file name. + + Raises: + SynapseError(404): if parsing or validation fail for any reason + """ + try: + # The type on postpath seems incorrect in Twisted 21.2.0. + postpath: List[bytes] = request.postpath # 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") + + # Validate the server name, raising if invalid + parse_and_validate_server_name(server_name) + + 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: SynapseRequest) -> 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: SynapseRequest, + 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 + + 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) + + +def add_file_headers( + request: Request, + media_type: str, + file_size: Optional[int], + upload_name: Optional[str], +) -> None: + """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. + """ + + def _quote(x: str) -> str: + 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")) + 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 + # 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): + disposition = "inline; filename=%s" % (upload_name,) + else: + disposition = "inline; filename*=utf-8''%s" % (_quote(upload_name),) + + request.setHeader(b"Content-Disposition", disposition.encode("ascii")) + + # 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,)) + + # 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") + + +# 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: SynapseRequest, + responder: "Optional[Responder]", + media_type: str, + file_size: Optional[int], + upload_name: Optional[str] = None, +) -> None: + """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. + """ + if not responder: + respond_404(request) + return + + # If we have a responder we *must* use it as a context manager. + with responder: + if request._disconnected: + logger.warning( + "Not sending response to request %s, already disconnected.", request + ) + return + + logger.debug("Responding to media request with responder %s", responder) + add_file_headers(request, media_type, file_size, upload_name) + try: + 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() + + finish_request(request) + + +class Responder(ABC): + """Represents a response that can be streamed to the requester. + + Responder is a context manager which *must* be used, so that any resources + held can be cleaned up. + """ + + @abstractmethod + def write_to_consumer(self, consumer: IConsumer) -> Awaitable: + """Stream response into consumer + + Args: + consumer: The consumer to stream into. + + Returns: + Resolves once the response has finished being written + """ + raise NotImplementedError() + + def __enter__(self) -> None: # noqa: B027 + pass + + def __exit__( # noqa: B027 + self, + exc_type: Optional[Type[BaseException]], + exc_val: Optional[BaseException], + exc_tb: Optional[TracebackType], + ) -> None: + pass + + +@attr.s(slots=True, frozen=True, auto_attribs=True) +class ThumbnailInfo: + """Details about a generated thumbnail.""" + + width: int + height: int + method: str + # Content type of thumbnail, e.g. image/png + type: str + # The size of the media file, in bytes. + length: Optional[int] = None + + +@attr.s(slots=True, frozen=True, auto_attribs=True) +class FileInfo: + """Details about a requested/uploaded file.""" + + # The server name where the media originated from, or None if local. + server_name: Optional[str] + # The local ID of the file. For local files this is the same as the media_id + file_id: str + # If the file is for the url preview cache + url_cache: bool = False + # Whether the file is a thumbnail or not. + thumbnail: Optional[ThumbnailInfo] = None + + # The below properties exist to maintain compatibility with third-party modules. + @property + def thumbnail_width(self) -> Optional[int]: + if not self.thumbnail: + return None + return self.thumbnail.width + + @property + def thumbnail_height(self) -> Optional[int]: + if not self.thumbnail: + return None + return self.thumbnail.height + + @property + def thumbnail_method(self) -> Optional[str]: + if not self.thumbnail: + return None + return self.thumbnail.method + + @property + def thumbnail_type(self) -> Optional[str]: + if not self.thumbnail: + return None + return self.thumbnail.type + + @property + def thumbnail_length(self) -> Optional[int]: + if not self.thumbnail: + return None + return self.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. + """ + 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. + 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): + 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 + """ + parts = _parseparam(b";" + line) + key = next(parts) + pdict = {} + for p in parts: + i = p.find(b"=") + if i >= 0: + name = p[:i].strip().lower() + value = p[i + 1 :].strip() + + # strip double-quotes + if len(value) >= 2 and value[0:1] == value[-1:] == b'"': + value = value[1:-1] + 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 + """ + while s[:1] == b";": + s = s[1:] + + # look for the next ; + 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: + end = s.find(b";", end + 1) + + if end < 0: + end = len(s) + f = s[:end] + yield f.strip() + s = s[end:] |