Compact JSON-LD signed incoming activities (#17426)

Co-authored-by: Puck Meerburg <puck@puck.moe>

app/helpers/context_helper.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+module ContextHelper
+  NAMED_CONTEXT_MAP = {
+    activitystreams: 'https://www.w3.org/ns/activitystreams',
+    security: 'https://w3id.org/security/v1',
+  }.freeze
+
+  CONTEXT_EXTENSION_MAP = {
+    manually_approves_followers: { 'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers' },
+    sensitive: { 'sensitive' => 'as:sensitive' },
+    hashtag: { 'Hashtag' => 'as:Hashtag' },
+    moved_to: { 'movedTo' => { '@id' => 'as:movedTo', '@type' => '@id' } },
+    also_known_as: { 'alsoKnownAs' => { '@id' => 'as:alsoKnownAs', '@type' => '@id' } },
+    emoji: { 'toot' => 'http://joinmastodon.org/ns#', 'Emoji' => 'toot:Emoji' },
+    featured: { 'toot' => 'http://joinmastodon.org/ns#', 'featured' => { '@id' => 'toot:featured', '@type' => '@id' }, 'featuredTags' => { '@id' => 'toot:featuredTags', '@type' => '@id' } },
+    property_value: { 'schema' => 'http://schema.org#', 'PropertyValue' => 'schema:PropertyValue', 'value' => 'schema:value' },
+    atom_uri: { 'ostatus' => 'http://ostatus.org#', 'atomUri' => 'ostatus:atomUri' },
+    conversation: { 'ostatus' => 'http://ostatus.org#', 'inReplyToAtomUri' => 'ostatus:inReplyToAtomUri', 'conversation' => 'ostatus:conversation' },
+    focal_point: { 'toot' => 'http://joinmastodon.org/ns#', 'focalPoint' => { '@container' => '@list', '@id' => 'toot:focalPoint' } },
+    blurhash: { 'toot' => 'http://joinmastodon.org/ns#', 'blurhash' => 'toot:blurhash' },
+    discoverable: { 'toot' => 'http://joinmastodon.org/ns#', 'discoverable' => 'toot:discoverable' },
+    voters_count: { 'toot' => 'http://joinmastodon.org/ns#', 'votersCount' => 'toot:votersCount' },
+    olm: { 'toot' => 'http://joinmastodon.org/ns#', 'Device' => 'toot:Device', 'Ed25519Signature' => 'toot:Ed25519Signature', 'Ed25519Key' => 'toot:Ed25519Key', 'Curve25519Key' => 'toot:Curve25519Key', 'EncryptedMessage' => 'toot:EncryptedMessage', 'publicKeyBase64' => 'toot:publicKeyBase64', 'deviceId' => 'toot:deviceId', 'claim' => { '@type' => '@id', '@id' => 'toot:claim' }, 'fingerprintKey' => { '@type' => '@id', '@id' => 'toot:fingerprintKey' }, 'identityKey' => { '@type' => '@id', '@id' => 'toot:identityKey' }, 'devices' => { '@type' => '@id', '@id' => 'toot:devices' }, 'messageFranking' => 'toot:messageFranking', 'messageType' => 'toot:messageType', 'cipherText' => 'toot:cipherText' },
+    suspended: { 'toot' => 'http://joinmastodon.org/ns#', 'suspended' => 'toot:suspended' },
+  }.freeze
+
+  def full_context
+    serialized_context(NAMED_CONTEXT_MAP, CONTEXT_EXTENSION_MAP)
+  end
+
+  def serialized_context(named_contexts_map, context_extensions_map)
+    context_array = []
+
+    named_contexts     = named_contexts_map.keys
+    context_extensions = context_extensions_map.keys
+
+    named_contexts.each do |key|
+      context_array << NAMED_CONTEXT_MAP[key]
+    end
+
+    extensions = context_extensions.each_with_object({}) do |key, h|
+      h.merge!(CONTEXT_EXTENSION_MAP[key])
+    end
+
+    context_array << extensions unless extensions.empty?
+
+    if context_array.size == 1
+      context_array.first
+    else
+      context_array
+    end
+  end
+end

app/helpers/jsonld_helper.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 module JsonLdHelper
+  include ContextHelper
+
   def equals_or_includes?(haystack, needle)
     haystack.is_a?(Array) ? haystack.include?(needle) : haystack == needle
   end
@@ -69,6 +71,12 @@ module JsonLdHelper
     graph.dump(:normalize)
   end
 
+  def compact(json)
+    compacted = JSON::LD::API.compact(json.without('signature'), full_context, documentLoader: method(:load_jsonld_context))
+    compacted['signature'] = json['signature']
+    compacted
+  end
+
   def fetch_resource(uri, id, on_behalf_of = nil)
     unless id
       json = fetch_resource_without_id_validation(uri, on_behalf_of)

app/lib/activitypub/adapter.rb

@@ -1,29 +1,7 @@
 # frozen_string_literal: true
 
 class ActivityPub::Adapter < ActiveModelSerializers::Adapter::Base
-  NAMED_CONTEXT_MAP = {
-    activitystreams: 'https://www.w3.org/ns/activitystreams',
-    security: 'https://w3id.org/security/v1',
-  }.freeze
-
-  CONTEXT_EXTENSION_MAP = {
-    manually_approves_followers: { 'manuallyApprovesFollowers' => 'as:manuallyApprovesFollowers' },
-    sensitive: { 'sensitive' => 'as:sensitive' },
-    hashtag: { 'Hashtag' => 'as:Hashtag' },
-    moved_to: { 'movedTo' => { '@id' => 'as:movedTo', '@type' => '@id' } },
-    also_known_as: { 'alsoKnownAs' => { '@id' => 'as:alsoKnownAs', '@type' => '@id' } },
-    emoji: { 'toot' => 'http://joinmastodon.org/ns#', 'Emoji' => 'toot:Emoji' },
-    featured: { 'toot' => 'http://joinmastodon.org/ns#', 'featured' => { '@id' => 'toot:featured', '@type' => '@id' }, 'featuredTags' => { '@id' => 'toot:featuredTags', '@type' => '@id' } },
-    property_value: { 'schema' => 'http://schema.org#', 'PropertyValue' => 'schema:PropertyValue', 'value' => 'schema:value' },
-    atom_uri: { 'ostatus' => 'http://ostatus.org#', 'atomUri' => 'ostatus:atomUri' },
-    conversation: { 'ostatus' => 'http://ostatus.org#', 'inReplyToAtomUri' => 'ostatus:inReplyToAtomUri', 'conversation' => 'ostatus:conversation' },
-    focal_point: { 'toot' => 'http://joinmastodon.org/ns#', 'focalPoint' => { '@container' => '@list', '@id' => 'toot:focalPoint' } },
-    blurhash: { 'toot' => 'http://joinmastodon.org/ns#', 'blurhash' => 'toot:blurhash' },
-    discoverable: { 'toot' => 'http://joinmastodon.org/ns#', 'discoverable' => 'toot:discoverable' },
-    voters_count: { 'toot' => 'http://joinmastodon.org/ns#', 'votersCount' => 'toot:votersCount' },
-    olm: { 'toot' => 'http://joinmastodon.org/ns#', 'Device' => 'toot:Device', 'Ed25519Signature' => 'toot:Ed25519Signature', 'Ed25519Key' => 'toot:Ed25519Key', 'Curve25519Key' => 'toot:Curve25519Key', 'EncryptedMessage' => 'toot:EncryptedMessage', 'publicKeyBase64' => 'toot:publicKeyBase64', 'deviceId' => 'toot:deviceId', 'claim' => { '@type' => '@id', '@id' => 'toot:claim' }, 'fingerprintKey' => { '@type' => '@id', '@id' => 'toot:fingerprintKey' }, 'identityKey' => { '@type' => '@id', '@id' => 'toot:identityKey' }, 'devices' => { '@type' => '@id', '@id' => 'toot:devices' }, 'messageFranking' => 'toot:messageFranking', 'messageType' => 'toot:messageType', 'cipherText' => 'toot:cipherText' },
-    suspended: { 'toot' => 'http://joinmastodon.org/ns#', 'suspended' => 'toot:suspended' },
-  }.freeze
+  include ContextHelper
 
   def self.default_key_transform
     :camel_lower
@@ -34,7 +12,7 @@ class ActivityPub::Adapter < ActiveModelSerializers::Adapter::Base
   end
 
   def serializable_hash(options = nil)
-    named_contexts     = {}
+    named_contexts     = { activitystreams: NAMED_CONTEXT_MAP['activitystreams'] }
     context_extensions = {}
 
     options         = serialization_options(options)
@@ -44,29 +22,4 @@ class ActivityPub::Adapter < ActiveModelSerializers::Adapter::Base
 
     { '@context' => serialized_context(named_contexts, context_extensions) }.merge(serialized_hash)
   end
-
-  private
-
-  def serialized_context(named_contexts_map, context_extensions_map)
-    context_array = []
-
-    named_contexts     = [:activitystreams] + named_contexts_map.keys
-    context_extensions = context_extensions_map.keys
-
-    named_contexts.each do |key|
-      context_array << NAMED_CONTEXT_MAP[key]
-    end
-
-    extensions = context_extensions.each_with_object({}) do |key, h|
-      h.merge!(CONTEXT_EXTENSION_MAP[key])
-    end
-
-    context_array << extensions unless extensions.empty?
-
-    if context_array.size == 1
-      context_array.first
-    else
-      context_array
-    end
-  end
 end

app/services/activitypub/process_collection_service.rb

@@ -8,6 +8,8 @@ class ActivityPub::ProcessCollectionService < BaseService
     @json    = Oj.load(body, mode: :strict)
     @options = options
 
+    @json = compact(@json) if @json['signature'].is_a?(Hash)
+
     return if !supported_context? || (different_actor? && verify_account!.nil?) || suspended_actor? || @account.local?
 
     case @json['type']