Fetch reblogs as Announce activity instead of Note object (#4672)

* Process Create / Announce activity in FetchRemoteStatusService

* Use activity URL in ActivityPub for reblogs

* Redirect to the original status on StatusesController#show

4 files changed, 35 insertions, 10 deletions

diff --git a/app/controllers/statuses_controller.rb b/app/controllers/statuses_controller.rb
index aa24f23c9..a9768d092 100644
--- a/app/controllers/statuses_controller.rb
+++ b/app/controllers/statuses_controller.rb
@@ -9,6 +9,7 @@ class StatusesController < ApplicationController
   before_action :set_status
   before_action :set_link_headers
   before_action :check_account_suspension
+  before_action :redirect_to_original, only: [:show]
 
   def show
     respond_to do |format|
@@ -58,4 +59,8 @@ class StatusesController < ApplicationController
   def check_account_suspension
     gone if @account.suspended?
   end
+
+  def redirect_to_original
+    redirect_to ::TagManager.instance.url_for(@status.reblog) if @status.reblog?
+  end
 end
diff --git a/app/lib/activitypub/tag_manager.rb b/app/lib/activitypub/tag_manager.rb
index 3c16006cb..de575d9e6 100644
--- a/app/lib/activitypub/tag_manager.rb
+++ b/app/lib/activitypub/tag_manager.rb
@@ -19,6 +19,7 @@ class ActivityPub::TagManager
     when :person
       short_account_url(target)
     when :note, :comment, :activity
+      return activity_account_status_url(target.account, target) if target.reblog?
       short_account_status_url(target.account, target)
     end
   end
@@ -30,10 +31,17 @@ class ActivityPub::TagManager
     when :person
       account_url(target)
     when :note, :comment, :activity
+      return activity_account_status_url(target.account, target) if target.reblog?
       account_status_url(target.account, target)
     end
   end
 
+  def activity_uri_for(target)
+    return nil unless %i(note comment activity).include?(target.object_type) && target.local?
+
+    activity_account_status_url(target.account, target)
+  end
+
   # Primary audience of a status
   # Public statuses go out to primarily the public collection
   # Unlisted and private statuses go out primarily to the followers collection
diff --git a/app/serializers/activitypub/activity_serializer.rb b/app/serializers/activitypub/activity_serializer.rb
index 69e2160c5..d20ee9920 100644
--- a/app/serializers/activitypub/activity_serializer.rb
+++ b/app/serializers/activitypub/activity_serializer.rb
@@ -6,7 +6,7 @@ class ActivityPub::ActivitySerializer < ActiveModel::Serializer
   has_one :proper, key: :object, serializer: ActivityPub::NoteSerializer
 
   def id
-    [ActivityPub::TagManager.instance.uri_for(object), '/activity'].join
+    [ActivityPub::TagManager.instance.activity_uri_for(object)].join
   end
 
   def type
diff --git a/app/services/activitypub/fetch_remote_status_service.rb b/app/services/activitypub/fetch_remote_status_service.rb
index 993e5389c..c114515cd 100644
--- a/app/services/activitypub/fetch_remote_status_service.rb
+++ b/app/services/activitypub/fetch_remote_status_service.rb
@@ -7,21 +7,33 @@ class ActivityPub::FetchRemoteStatusService < BaseService
   def call(uri, prefetched_json = nil)
     @json = body_to_json(prefetched_json) || fetch_resource(uri)
 
-    return unless supported_context? && expected_type?
+    return unless supported_context?
 
-    attributed_to = first_of_value(@json['attributedTo'])
-    attributed_to = attributed_to['id'] if attributed_to.is_a?(Hash)
+    activity = activity_json
+    actor_id = value_or_id(activity['actor'])
 
-    return unless trustworthy_attribution?(uri, attributed_to)
+    return unless expected_type?(activity) && trustworthy_attribution?(uri, actor_id)
 
-    actor = ActivityPub::TagManager.instance.uri_to_resource(attributed_to, Account)
-    actor = ActivityPub::FetchRemoteAccountService.new.call(attributed_to) if actor.nil?
+    actor = ActivityPub::TagManager.instance.uri_to_resource(actor_id, Account)
+    actor = ActivityPub::FetchRemoteAccountService.new.call(actor_id) if actor.nil?
 
-    ActivityPub::Activity::Create.new({ 'object' => @json }, actor).perform
+    ActivityPub::Activity.factory(activity, actor).perform
   end
 
   private
 
+  def activity_json
+    if %w(Note Article).include? @json['type']
+      {
+        'type' => 'Create',
+        'actor' => first_of_value(@json['attributedTo']),
+        'object' => @json,
+      }
+    else
+      @json
+    end
+  end
+
   def trustworthy_attribution?(uri, attributed_to)
     Addressable::URI.parse(uri).normalized_host.casecmp(Addressable::URI.parse(attributed_to).normalized_host).zero?
   end
@@ -30,7 +42,7 @@ class ActivityPub::FetchRemoteStatusService < BaseService
     super(@json)
   end
 
-  def expected_type?
-    %w(Note Article).include? @json['type']
+  def expected_type?(json)
+    %w(Create Announce).include? json['type']
   end
 end