1 files changed, 50 insertions, 0 deletions
diff --git a/app/services/activity_pub/inbox_resolver_service.rb b/app/services/activity_pub/inbox_resolver_service.rb
new file mode 100644
index 00000000000..c2bd2112b16
--- /dev/null
+++ b/app/services/activity_pub/inbox_resolver_service.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+module ActivityPub
+  class InboxResolverService
+    attr_reader :subscription
+
+    def initialize(subscription)
+      @subscription = subscription
+    end
+
+    def execute
+      profile = subscriber_profile
+      unless profile.has_key?('inbox') && profile['inbox'].is_a?(String)
+        raise ThirdPartyError, 'Inbox parameter absent or invalid'
+      end
+
+      subscription.subscriber_inbox_url = profile['inbox']
+      subscription.shared_inbox_url = profile.dig('entrypoints', 'sharedInbox')
+      subscription.save!
+    end
+
+    private
+
+    def subscriber_profile
+      raw_data = download_subscriber_profile
+
+      begin
+        profile = Gitlab::Json.parse(raw_data)
+      rescue JSON::ParserError => e
+        raise ThirdPartyError, e.message
+      end
+
+      profile
+    end
+
+    def download_subscriber_profile
+      begin
+        response = Gitlab::HTTP.get(subscription.subscriber_url,
+          headers: {
+            'Accept' => 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'
+          }
+        )
+      rescue StandardError => e
+        raise ThirdPartyError, e.message
+      end
+
+      response.body
+    end
+  end
+end