e.g. if someone on an instance that previously had followers gets mentioned
in a private toot, before this PR, they would not receive a
Collection-Synchronization header and may show the toot to the former followers
in addition to the mentioned person.
* Add support for followers synchronization on the receiving end
Check the `collectionSynchronization` attribute on `Create` and `Announce`
activities and synchronize followers from provided collection if possible.
* Add tests for followers synchronization on the receiving end
* Add support for follower synchronization on the sender's end
* Add tests for the sending end
* Switch from AS attributes to HTTP header
Replace the custom `collectionSynchronization` ActivityStreams attribute by
an HTTP header (`X-AS-Collection-Synchronization`) with the same syntax as
the `Signature` header and the following fields:
- `collectionId` to specify which collection to synchronize
- `digest` for the SHA256 hex-digest of the list of followers known on the
receiving instance (where “receiving instance” is determined by accounts
sharing the same host name for their ActivityPub actor `id`)
- `url` of a collection that should be fetched by the instance actor
Internally, move away from the webfinger-based `domain` attribute and use
account `uri` prefix to group accounts.
* Add environment variable to disable followers synchronization
Since the whole mechanism relies on some new preconditions that, in some
extremely rare cases, might not be met, add an environment variable
(DISABLE_FOLLOWERS_SYNCHRONIZATION) to disable the mechanism altogether and
avoid followers being incorrectly removed.
The current conditions are:
1. all managed accounts' actor `id` and inbox URL have the same URI scheme and
netloc.
2. all accounts whose actor `id` or inbox URL share the same URI scheme and
netloc as a managed account must be managed by the same Mastodon instance
as well.
As far as Mastodon is concerned, breaking those preconditions require extensive
configuration changes in the reverse proxy and might also cause other issues.
Therefore, this environment variable provides a way out for people with highly
unusual configurations, and can be safely ignored for the overwhelming majority
of Mastodon administrators.
* Only set follower synchronization header on non-public statuses
This is to avoid unnecessary computations and allow Follow-related
activities to be handled by the usual codepath instead of going through
the synchronization mechanism (otherwise, any Follow/Undo/Accept activity
would trigger the synchronization mechanism even if processing the activity
itself would be enough to re-introduce synchronization)
* Change how ActivityPub::SynchronizeFollowersService handles follow requests
If the remote lists a local follower which we only know has sent a follow
request, consider the follow request as accepted instead of sending an Undo.
* Integrate review feeback
- rename X-AS-Collection-Synchronization to Collection-Synchronization
- various minor refactoring and code style changes
* Only select required fields when computing followers_hash
* Use actor URI rather than webfinger domain in synchronization endpoint
* Change hash computation to be a XOR of individual hashes
Makes it much easier to be memory-efficient, and avoid sorting discrepancy issues.
* Marginally improve followers_hash computation speed
* Further improve hash computation performances by using pluck_each
* Add support for latest HTTP Signatures spec draft
https://www.ietf.org/id/draft-ietf-httpbis-message-signatures-00.html
- add support for the “hs2019” signature algorithm (assumed to be equivalent
to RSA-SHA256, since we do not have a mechanism to specify the algorithm
within the key metadata yet)
- add support for (created) and (expires) pseudo-headers and related
signature parameters, when using the hs2019 signature algorithm
- adjust default “headers” parameter while being backwards-compatible with
previous implementation
- change the acceptable time window logic from 12 hours surrounding the “date”
header to accepting signatures created up to 1 hour in the future and
expiring up to 1 hour in the past (but only allowing expiration dates up to
12 hours after the creation date)
This doesn't conform with the current draft, as it doesn't permit accounting
for clock skew.
This, however, should be addressed in a next version of the draft:
https://github.com/httpwg/http-extensions/pull/1235
* Add additional signature requirements
* Rewrite signature params parsing using Parslet
* Make apparent which signature algorithm Mastodon on verification failure
Mastodon uses RSASSA-PKCS1-v1_5, which is not recommended for new applications,
and new implementers may thus unknowingly use RSASSA-PSS.
* Add workaround for PeerTube's invalid signature header
The previous parser allowed incorrect Signature headers, such as
those produced by old versions of the `http-signature` node.js package,
and seemingly used by PeerTube.
This commit adds a workaround for that.
* Fix `signature_key_id` raising an exception
Previously, parsing failures would result in `signature_key_id` being nil,
but the parser changes made that result in an exception.
This commit changes the `signature_key_id` method to return `nil` in case
of parsing failures.
* Move extra HTTP signature helper methods to private methods
* Relax (request-target) requirement to (request-target) || digest
This lets requests from Plume work without lowering security significantly.
Follow-up to #14359
In the case of limited toots, the receiver may not be explicitly part of the
audience. If a specific user's inbox URI was specified, it makes sense to
dereference the toot from the corresponding user, instead of trying to find
someone in the explicit audience.
* Fix contrast calculation for thumbnail color extraction
Luminance calculation was using 0-255 RGB values instead of 0-1 sRGB values,
leading to incorrectly-computed contrast values.
Since we use ColorDiff already, just use its XYZ colorspace conversion code
to get the value.
* Require at least 3:1 contrast for both accent and foreground colors
* Lower required contrast for the accent color
* Change content-type to be always computed from file data
Restore previous behavior, detecting the content-type isn't very
expensive, and some instances may serve files as application/octet-stream
regardless of their true type, making fetching media from them fail, while
it used to work pre-3.2.0.
* Add test
There are edge cases where requests to certain hosts timeout when
using the vanilla HTTP.rb gem, which the goldfinger gem uses. Now
that we no longer need to support OStatus servers, webfinger logic
is so simple that there is no point encapsulating it in a gem, so
we can just use our own Request class. With that, we benefit from
more robust timeout code and IPv4/IPv6 resolution.
Fix#14091
* Do not serve account actors at all in limited federation mode
When an account is fetched without a signature from an allowed instance,
return an error.
This isn't really an improvement in security, as the only information that was
previously returned was required protocol-level info, and the only personal bit
was the existence of the account. The existence of the account can still be
checked by issuing a webfinger query, as those are accepted without signatures.
However, this change makes it so that unallowed instances won't create account
records on their end when they find a reference to an unknown account.
The previous behavior of rendering a limited list of fields, instead of not
rendering the actor at all, was in order to prevent situations in which two
instances in Authorized Fetch mode or Limited Federation mode would fail to
reach each other because resolving an account would require a signed query…
from an account which can only be fetched with a signed query itself. However,
this should now be fine as fetching accounts is done by signing on behalf of
the special instance actor, which does not require any kind of valid signature
to be fetched.
* Fix tests
