The 'time' caveat on the access tokens was something of a lie, since we weren't
enforcing it; more pertinently its presence stops us ever adding useful time
caveats.
Let's move in the right direction by not lying in our caveats.
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.
This follows the same flows-based flow as regular registration, but as
the only implemented flow has no requirements, it auto-succeeds. In the
future, other flows (e.g. captcha) may be required, so clients should
treat this like the regular registration flow choices.
SYN-287
This requires that HS owners either opt in or out of stats reporting.
When --generate-config is passed, --report-stats must be specified
If an already-generated config is used, and doesn't have the
report_stats key, it is requested to be set.
This just replaces random bytes with macaroons. The macaroons are not
inspected by the client or server.
In particular, they claim to have an expiry time, but nothing verifies
that they have not expired.
Follow-up commits will actually enforce the expiration, and allow for
token refresh.
See https://bit.ly/matrix-auth for more information
