When we proxy a media request to a remote server, add a query-param, which will
tell the remote server to 404 if it doesn't recognise the server_name.
This should fix a routing loop where the server keeps forwarding back to
itself.
Also improves the error handling on remote media fetches, so that we don't
always return a rather obscure 502.
This includes:
- Splitting out methods of a class into stand alone functions, to make
them easier to test.
- Adding unit tests to split out functions, testing HTML -> preview.
- Handle the fact that elements in lxml may have tail text.
Using XPath is slow on some machines (for unknown reasons), so use a
different approach to get a list of text nodes.
Try to generate a summary that respect paragraph and then word
boundaries, adding ellipses when appropriate.
The existing content can still be downloaded. The last upload to the
matrix.org server was in January 2015, so it is probably safe to remove
the upload API.
Always set the config key with an empty list, even if a list isn't specified.
This means that the codepaths are the same for both the empty list and
for a missing key. Since the behaviour is the same for both cases this
makes the code somewhat easier to reason about.
This is so that a single MediaRepository can be shared across all
resources, rather than having a "copy" per resource.
In particular this allows us to guard against both the thumbnail and
download resource triggering a download of remote content at the same
time.
Add url_preview_ip_range_blacklist to let admins specify internal IP ranges that must not be spidered.
Add url_preview_url_blacklist to let admins specify URL patterns that must not be spidered.
Implement a custom SpiderEndpoint and associated support classes to implement url_preview_ip_range_blacklist
Add commentary and generally address PR feedback
