From f29918e7071160f277ac5834d83e409d8fa20063 Mon Sep 17 00:00:00 2001
From: ThibG <thib@sitedethib.com>
Date: Tue, 12 Sep 2017 23:10:40 +0200
Subject: [PATCH] =?UTF-8?q?[WiP]=20Whenever=20a=20remote=20keypair=20chang?=
=?UTF-8?q?es,=20unfollow=20them=20and=20re-subscribe=20to=20=E2=80=A6=20(?=
=?UTF-8?q?#4907)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
* Whenever a remote keypair changes, unfollow them and re-subscribe to them
In Mastodon (it could be different for other OStatus or AP-enabled software),
a keypair change is indicative of whole user (or instance) data loss. In this
situation, the “new” user might be different, and almost certainly has an empty
followers list. In this case, Mastodon instances will disagree on follower
lists, leading to unreliable delivery and “shadow followers”, that is users
believed by a remote instance to be followers, without the affected user
knowing.
Drawbacks of this change are:
1. If an user legitimately changes public key for some reason without losing
data (not possible in Mastodon at the moment), they will have their remote
followers unsubscribed/re-subscribed needlessly.
2. Depending of the number of remote followers, this may generate quite some
traffic.
3. If the user change is an attempt at usurpation, the remote followers will
unknowingly follow the usurper. Note that this is *not* a change of
behavior, Mastodon already behaves like that, although delivery might be
unreliable, and the usurper would not have known the former user's
followers.
* Rename ResubscribeWorker to RefollowWorker
* Process followers in batches
---
.../activitypub/process_account_service.rb | 2 ++
.../resolve_remote_account_service.rb | 2 ++
app/workers/refollow_worker.rb | 23 +++++++++++++++++++
3 files changed, 27 insertions(+)
create mode 100644 app/workers/refollow_worker.rb
diff --git a/app/services/activitypub/process_account_service.rb b/app/services/activitypub/process_account_service.rb
index b54e447ad..badb26720 100644
--- a/app/services/activitypub/process_account_service.rb
+++ b/app/services/activitypub/process_account_service.rb
@@ -17,7 +17,9 @@ class ActivityPub::ProcessAccountService < BaseService
create_account if @account.nil?
upgrade_account if @account.ostatus?
+ old_public_key = @account.public_key
update_account
+ RefollowWorker.perform_async(@account.id) if old_public_key != @account.public_key
@account
rescue Oj::ParseError
diff --git a/app/services/resolve_remote_account_service.rb b/app/services/resolve_remote_account_service.rb
index 7031c98f5..753601501 100644
--- a/app/services/resolve_remote_account_service.rb
+++ b/app/services/resolve_remote_account_service.rb
@@ -85,8 +85,10 @@ class ResolveRemoteAccountService < BaseService
def handle_ostatus
create_account if @account.nil?
+ old_public_key = @account.public_key
update_account
update_account_profile if update_profile?
+ RefollowWorker.perform_async(@account.id) if old_public_key != @account.public_key
end
def update_profile?
diff --git a/app/workers/refollow_worker.rb b/app/workers/refollow_worker.rb
new file mode 100644
index 000000000..9c42d4271
--- /dev/null
+++ b/app/workers/refollow_worker.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class RefollowWorker
+ include Sidekiq::Worker
+
+ sidekiq_options queue: 'pull', retry: false
+
+ def perform(target_account_id)
+ target_account = Account.find(target_account_id)
+
+ target_account.followers.where(domain: nil).find_each do |follower|
+ # Locally unfollow remote account
+ follower.unfollow!(target_account)
+
+ # Schedule re-follow
+ begin
+ FollowService.new.call(follower, target_account)
+ rescue Mastodon::NotPermittedError, ActiveRecord::RecordNotFound, Mastodon::UnexpectedResponseError, HTTP::Error, OpenSSL::SSL::SSLError
+ next
+ end
+ end
+ end
+end