Fix followers synchronization mechanism not working when URI has empty path (#16510)

* Fix followers synchronization mechanism not working when URI has empty path

To my knowledge, there is no current implementation on the fediverse
that can use bare domains (e.g., actor is at https://example.org instead of
something like https://example.org/actor) that also plans to support the
followers synchronization mechanism. However, Mastodon's current implementation
would exclude such accounts from followers list.

Also adds tests and rename them to reflect the proper method names.

* Move url prefix regexp to its own constant

1 files changed, 6 insertions, 3 deletions

diff --git a/app/models/concerns/account_interactions.rb b/app/models/concerns/account_interactions.rb
index 4bf62539c..8f19176a7 100644
--- a/app/models/concerns/account_interactions.rb
+++ b/app/models/concerns/account_interactions.rb
@@ -254,10 +254,13 @@ module AccountInteractions
          .where('users.current_sign_in_at > ?', User::ACTIVE_DURATION.ago)
   end
 
-  def remote_followers_hash(url_prefix)
-    Rails.cache.fetch("followers_hash:#{id}:#{url_prefix}") do
+  def remote_followers_hash(url)
+    url_prefix = url[Account::URL_PREFIX_RE]
+    return if url_prefix.blank?
+
+    Rails.cache.fetch("followers_hash:#{id}:#{url_prefix}/") do
       digest = "\x00" * 32
-      followers.where(Account.arel_table[:uri].matches(url_prefix + '%', false, true)).pluck_each(:uri) do |uri|
+      followers.where(Account.arel_table[:uri].matches("#{Account.sanitize_sql_like(url_prefix)}/%", false, true)).or(followers.where(uri: url_prefix)).pluck_each(:uri) do |uri|
         Xorcist.xor!(digest, Digest::SHA256.digest(uri))
       end
       digest.unpack('H*')[0]