Fix URI of repeat follow requests not being recorded (#15662)

* Fix URI of repeat follow requests not being recorded

In case we receive a “repeat” or “duplicate” follow request, we automatically
fast-forward the accept with the latest received Activity `id`, but we don't
record it.

In general, a “repeat” or “duplicate” follow request may happen if for some
reason (e.g. inconsistent handling of Block or Undo Accept activities, an
instance being brought back up from the dead, etc.) the local instance thought
the remote actor were following them while the remote actor thought otherwise.

In those cases, the remote instance does not know about the older Follow
activity `id`, so keeping that record serves no purpose, but knowing the most
recent one is useful if the remote implementation at some point refers to it
by `id` without inlining it.

* Add tests

app/lib/activitypub/activity/follow.rb

@@ -6,7 +6,14 @@ class ActivityPub::Activity::Follow < ActivityPub::Activity
   def perform
     target_account = account_from_uri(object_uri)
 
-    return if target_account.nil? || !target_account.local? || delete_arrived_first?(@json['id']) || @account.requested?(target_account)
+    return if target_account.nil? || !target_account.local? || delete_arrived_first?(@json['id'])
+
+    # Update id of already-existing follow requests
+    existing_follow_request = ::FollowRequest.find_by(account: @account, target_account: target_account)
+    unless existing_follow_request.nil?
+      existing_follow_request.update!(uri: @json['id'])
+      return
+    end
 
     if target_account.blocking?(@account) || target_account.domain_blocking?(@account.domain) || target_account.moved? || target_account.instance_actor?
       reject_follow_request!(target_account)
@@ -14,7 +21,9 @@ class ActivityPub::Activity::Follow < ActivityPub::Activity
     end
 
     # Fast-forward repeat follow requests
-    if @account.following?(target_account)
+    existing_follow = ::Follow.find_by(account: @account, target_account: target_account)
+    unless existing_follow.nil?
+      existing_follow.update!(uri: @json['id'])
       AuthorizeFollowService.new.call(@account, target_account, skip_follow_request: true, follow_request_uri: @json['id'])
       return
     end

spec/lib/activitypub/activity/follow_spec.rb

@@ -17,6 +17,7 @@ RSpec.describe ActivityPub::Activity::Follow do
   describe '#perform' do
     subject { described_class.new(json, sender) }
 
+    context 'with no prior follow' do
       context 'unlocked account' do
         before do
           subject.perform
@@ -24,6 +25,7 @@ RSpec.describe ActivityPub::Activity::Follow do
 
         it 'creates a follow from sender to recipient' do
           expect(sender.following?(recipient)).to be true
+          expect(sender.active_relationships.find_by(target_account: recipient).uri).to eq 'foo'
         end
 
         it 'does not create a follow request' do
@@ -43,6 +45,7 @@ RSpec.describe ActivityPub::Activity::Follow do
 
         it 'creates a follow request' do
           expect(sender.requested?(recipient)).to be true
+          expect(sender.follow_requests.find_by(target_account: recipient).uri).to eq 'foo'
         end
       end
 
@@ -54,6 +57,7 @@ RSpec.describe ActivityPub::Activity::Follow do
 
         it 'creates a follow from sender to recipient' do
           expect(sender.following?(recipient)).to be true
+          expect(sender.active_relationships.find_by(target_account: recipient).uri).to eq 'foo'
         end
 
         it 'does not create a follow request' do
@@ -73,6 +77,111 @@ RSpec.describe ActivityPub::Activity::Follow do
 
         it 'creates a follow request' do
           expect(sender.requested?(recipient)).to be true
+          expect(sender.follow_requests.find_by(target_account: recipient).uri).to eq 'foo'
+        end
+      end
+    end
+
+    context 'when a follow relationship already exists' do
+      before do
+        sender.active_relationships.create!(target_account: recipient, uri: 'bar')
+      end
+
+      context 'unlocked account' do
+        before do
+          subject.perform
+        end
+
+        it 'correctly sets the new URI' do
+          expect(sender.active_relationships.find_by(target_account: recipient).uri).to eq 'foo'
+        end
+
+        it 'does not create a follow request' do
+          expect(sender.requested?(recipient)).to be false
+        end
+      end
+
+      context 'silenced account following an unlocked account' do
+        before do
+          sender.touch(:silenced_at)
+          subject.perform
+        end
+
+        it 'correctly sets the new URI' do
+          expect(sender.active_relationships.find_by(target_account: recipient).uri).to eq 'foo'
+        end
+
+        it 'does not create a follow request' do
+          expect(sender.requested?(recipient)).to be false
+        end
+      end
+
+      context 'unlocked account muting the sender' do
+        before do
+          recipient.mute!(sender)
+          subject.perform
+        end
+
+        it 'correctly sets the new URI' do
+          expect(sender.active_relationships.find_by(target_account: recipient).uri).to eq 'foo'
+        end
+
+        it 'does not create a follow request' do
+          expect(sender.requested?(recipient)).to be false
+        end
+      end
+
+      context 'locked account' do
+        before do
+          recipient.update(locked: true)
+          subject.perform
+        end
+
+        it 'correctly sets the new URI' do
+          expect(sender.active_relationships.find_by(target_account: recipient).uri).to eq 'foo'
+        end
+
+        it 'does not create a follow request' do
+          expect(sender.requested?(recipient)).to be false
+        end
+      end
+    end
+
+    context 'when a follow request already exists' do
+      before do
+        sender.follow_requests.create!(target_account: recipient, uri: 'bar')
+      end
+
+      context 'silenced account following an unlocked account' do
+        before do
+          sender.touch(:silenced_at)
+          subject.perform
+        end
+
+        it 'does not create a follow from sender to recipient' do
+          expect(sender.following?(recipient)).to be false
+        end
+
+        it 'correctly sets the new URI' do
+          expect(sender.requested?(recipient)).to be true
+          expect(sender.follow_requests.find_by(target_account: recipient).uri).to eq 'foo'
+        end
+      end
+
+      context 'locked account' do
+        before do
+          recipient.update(locked: true)
+          subject.perform
+        end
+
+        it 'does not create a follow from sender to recipient' do
+          expect(sender.following?(recipient)).to be false
+        end
+
+        it 'correctly sets the new URI' do
+          expect(sender.requested?(recipient)).to be true
+          expect(sender.follow_requests.find_by(target_account: recipient).uri).to eq 'foo'
+        end
       end
     end
   end