Renames ``load_config`` to ``load_or_generate_config``
Adds a method called ``load_config`` that just loads the
config.
The main synapse.app.homeserver will continue to use
``load_or_generate_config`` to retain backwards compat.
However new worker processes can use ``load_config`` to
load the config avoiding some of the cruft needed to generate
the config.
As the new ``load_config`` method is expected to be used by new
configs it removes support for the legacy commandline overrides
that ``load_or_generate_config`` supports
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.
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
Currently, when a 3pid invite request is sent to an identity server, it
includes a provisioned guest access token. This allows the link in the,
say, invite email to include the guest access token ensuring that the
same account is used each time the link is clicked.
This flow has a number of flaws, including when using different servers
or servers that have guest access disabled.
For now, we keep this implementation but hide it behind a config option
until a better flow is implemented.
Unfortunately, there are people that are running synapse without a
`macaroon_sercret_key` set. Mandating they set one is a good solution,
except that breaking auto upgrades is annoying.
Currently we store all access tokens in the DB, and fall back to that
check if we can't validate the macaroon, so our fallback works here, but
for guests, their macaroons don't get persisted, so we don't get to
find them in the database. Each restart, we generate a new ephemeral
key, so guests lose access after each server restart.
I tried to fix up the config stuff to be less insane, but gave up, so
instead I bolt on yet another piece of custom one-off insanity.
Also, add some basic tests for config generation and loading.
