filter inbox with domain blocks

config/initializers/extensions.rb

@@ -0,0 +1,3 @@
+require "fediverse/inbox"
+require "federails/moderation/filtered_inbox"
+Fediverse::Inbox.send(:include, Federails::Moderation::FilteredInbox)

lib/federails/moderation/filtered_inbox.rb

@@ -0,0 +1,18 @@
+module Federails::Moderation
+  module FilteredInbox
+    extend ActiveSupport::Concern
+
+    included do
+      class <<self
+        def filter_request(payload)
+          filtered_dispatch_request(payload) unless
+            (payload["id"] && DomainBlock.blocked?(URI.parse(payload["id"]).host)) ||
+            (payload["actor"] && DomainBlock.blocked?(URI.parse(payload["actor"]).host))
+        end
+
+        alias_method :filtered_dispatch_request, :dispatch_request
+        alias_method :dispatch_request, :filter_request
+      end
+    end
+  end
+end

spec/requests/domain_block_spec.rb

@@ -0,0 +1,33 @@
+RSpec.describe Federails::Moderation::DomainBlock do
+  let(:actor) { FactoryBot.create(:user).federails_actor }
+
+  describe 'with a blocked domain' do
+    before do
+      described_class.create(domain: "example.com")
+    end
+
+    it 'allows non-matching activities' do
+      payload = { "id" => "https://test.com/abc1234" }
+      expect(Fediverse::Inbox).to receive(:filtered_dispatch_request).with(payload)
+      Fediverse::Inbox.dispatch_request(payload)
+    end
+
+    it 'rejects activities with matching IDs' do
+      payload = { "id" => "https://example.com/abc1234" }
+      expect(Fediverse::Inbox).not_to receive(:filtered_dispatch_request)
+      Fediverse::Inbox.dispatch_request(payload)
+    end
+
+    it 'rejects activities with subdomain-matching IDs' do
+      payload = { "id" => "https://www.example.com/abc1234" }
+      expect(Fediverse::Inbox).not_to receive(:filtered_dispatch_request)
+      Fediverse::Inbox.dispatch_request(payload)
+    end
+
+    it 'rejects activities with matching actors' do
+      payload = { "actor" => "https://example.com/users/abc1234" }
+      expect(Fediverse::Inbox).not_to receive(:filtered_dispatch_request)
+      Fediverse::Inbox.dispatch_request(payload)
+    end
+  end
+end