Refactor media modules. (#15146)

* Removes the `v1` directory from `test.rest.media.v1`.
* Moves the non-REST code from `synapse.rest.media.v1` to `synapse.media`.
* Flatten the `v1` directory from `synapse.rest.media`,  but leave compatiblity
  with 3rd party media repositories and spam checkers.

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:]