1 files changed, 26 insertions, 12 deletions
diff --git a/app/services/activitypub/fetch_remote_account_service.rb b/app/services/activitypub/fetch_remote_account_service.rb
index 9d01f5386..d7d739c59 100644
--- a/app/services/activitypub/fetch_remote_account_service.rb
+++ b/app/services/activitypub/fetch_remote_account_service.rb
@@ -5,10 +5,12 @@ class ActivityPub::FetchRemoteAccountService < BaseService
   include DomainControlHelper
   include WebfingerHelper
 
+  class Error < StandardError; end
+
   SUPPORTED_TYPES = %w(Application Group Organization Person Service).freeze
 
   # Does a WebFinger roundtrip on each call, unless `only_key` is true
-  def call(uri, id: true, prefetched_body: nil, break_on_redirect: false, only_key: false)
+  def call(uri, id: true, prefetched_body: nil, break_on_redirect: false, only_key: false, suppress_errors: true)
     return if domain_not_allowed?(uri)
     return ActivityPub::TagManager.instance.uri_to_resource(uri, Account) if ActivityPub::TagManager.instance.local_uri?(uri)
 
@@ -18,38 +20,50 @@ class ActivityPub::FetchRemoteAccountService < BaseService
       else
         body_to_json(prefetched_body, compare_id: id ? uri : nil)
       end
+    rescue Oj::ParseError
+      raise Error, "Error parsing JSON-LD document #{uri}"
     end
 
-    return if !supported_context? || !expected_type? || (break_on_redirect && @json['movedTo'].present?)
+    raise Error, "Error fetching actor JSON at #{uri}" if @json.nil?
+    raise Error, "Unsupported JSON-LD context for document #{uri}" unless supported_context?
+    raise Error, "Unexpected object type for actor #{uri} (expected any of: #{SUPPORTED_TYPES})" unless expected_type?
+    raise Error, "Actor #{uri} has moved to #{@json['movedTo']}" if break_on_redirect && @json['movedTo'].present?
 
     @uri      = @json['id']
     @username = @json['preferredUsername']
     @domain   = Addressable::URI.parse(@uri).normalized_host
 
-    return unless only_key || verified_webfinger?
+    check_webfinger! unless only_key
 
     ActivityPub::ProcessAccountService.new.call(@username, @domain, @json, only_key: only_key, verified_webfinger: !only_key)
-  rescue Oj::ParseError
-    nil
+  rescue Error => e
+    Rails.logger.debug "Fetching account #{uri} failed: #{e.message}"
+    raise unless suppress_errors
   end
 
   private
 
-  def verified_webfinger?
+  def check_webfinger!
     webfinger                            = webfinger!("acct:#{@username}@#{@domain}")
     confirmed_username, confirmed_domain = split_acct(webfinger.subject)
 
-    return webfinger.link('self', 'href') == @uri if @username.casecmp(confirmed_username).zero? && @domain.casecmp(confirmed_domain).zero?
+    if @username.casecmp(confirmed_username).zero? && @domain.casecmp(confirmed_domain).zero?
+      raise Error, "Webfinger response for #{@username}@#{@domain} does not loop back to #{@uri}" if webfinger.link('self', 'href') != @uri
+      return
+    end
 
     webfinger                            = webfinger!("acct:#{confirmed_username}@#{confirmed_domain}")
     @username, @domain                   = split_acct(webfinger.subject)
 
-    return false unless @username.casecmp(confirmed_username).zero? && @domain.casecmp(confirmed_domain).zero?
-    return false if webfinger.link('self', 'href') != @uri
+    unless confirmed_username.casecmp(@username).zero? && confirmed_domain.casecmp(@domain).zero?
+      raise Webfinger::RedirectError, "Too many webfinger redirects for URI #{uri} (stopped at #{@username}@#{@domain})"
+    end
 
-    true
-  rescue Webfinger::Error
-    false
+    raise Error, "Webfinger response for #{@username}@#{@domain} does not loop back to #{@uri}" if webfinger.link('self', 'href') != @uri
+  rescue Webfinger::RedirectError => e
+    raise Error, e.message
+  rescue Webfinger::Error => e
+    raise Error, "Webfinger error when resolving #{@username}@#{@domain}: #{e.message}"
   end
 
   def split_acct(acct)