Current logic unconditionally adds public adressing to "cc"
and follower adressing to "to" after attempting to strip it
from the other one. This creates serious problems:
First the bug prompting this investigation and fix,
unconditional addition creates duplicates when adressing
URIs already were in their intended final field; e.g.
this is prominently the case for all "unlisted" posts.
Since List.delete only removes the first occurence,
this then broke follower-adress stripping later on
making the policy ineffective.
It’s also just not safe in general wrt to non-public adressing:
e.g. pre-existing duplicates didn’t get fully stripped,
bespoke adressing modes with only one of public addressing
or follower addressing are mangled — and most importantly:
any belatedly received DM or follower-only post
also got public adressing added!
Shockingly this last point was actually asserted as "correct" in tests;
it appears to be a mistake from mindless match adjustments
while fixing crashes on nil adressing in
10c792110e.
Clean up this sloppy logic up, making sure no more duplicates are
added by us, all instances of relevant adresses are purged and only
readded when they actually existed to begin with.
Current AP spec demands anonymous objects to have an id value,
but explicitly set it to JSON null. Howeveras it turns out this is
incompatible with JSON-LD requiring `@id` to be a string and thus AP
spec is incompatible iwth the Ativity Streams spec it is based on.
This is an issue for (the few) AP implementers actually performing
JSON-LD processing, like IceShrimp.NET.
This was uncovered by IceShrimp.NET’s zotan due to our adoption of
anonymous objects for emoj in f101886709.
The issues is being discussed by W3C, and will most likely be resolved
via an errata redefining anonymous objects to completely omit the id
field just like transient objects already do. See:
https://github.com/w3c/activitypub/issues/476
Fixes: https://akkoma.dev/AkkomaGang/akkoma/issues/848
Since we now remember the final location redirects lead to
and use it for all further checks since
3e134b07fa, these redirects
can no longer be exploited to serve counterfeit objects.
This fixes:
- display URLs from independent webapp clients
redirecting to the canonical domain
- Peertube display URLs for remote content
(acting like the above)
As hinted at in the commit message when strict checking
was added in 8684964c5d,
refetching is more robust than display URL comparison
but in exchange is harder to implement correctly.
A similar refetch approach is also employed by
e.g. Mastodon, IceShrimp and FireFish.
To make sure no checks can be bypassed by forcing
a refetch, id checking is placed at the very end.
This will fix:
- Peertube display URL arrays our transmogrifier fails to normalise
- non-canonical display URLs from alternative frontends
(theoretical; we didnt’t get any actual reports about this)
It will also be helpful in the planned key handling overhaul.
The modified user collision test was introduced in
https://git.pleroma.social/pleroma/pleroma/-/merge_requests/461
and unfortunately the issues this fixes aren’t public.
Afaict it was just meant to guard against someone serving
faked data belonging to an unrelated domain. Since we now
refetch and the id actually is mocked, lookup now succeeds
but will use the real data from the authorative server
making it unproblematic. Instead modify the fake data further
and make sure we don’t end up using the spoofed version.
