The whole point of verified_webfinger? is to check the WebFinger-discoverable URI maps back to the known author URI. This was not actually verified if the first Webfinger request was not a redirection.
		
			
				
	
	
		
			60 lines
		
	
	
		
			1.7 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
			
		
		
	
	
			60 lines
		
	
	
		
			1.7 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
# frozen_string_literal: true
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class ActivityPub::FetchRemoteAccountService < BaseService
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  include JsonLdHelper
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  # Should be called when uri has already been checked for locality
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  # Does a WebFinger roundtrip on each call
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  def call(uri, id: true, prefetched_body: nil)
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    @json = if prefetched_body.nil?
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              fetch_resource(uri, id)
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            else
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              body_to_json(prefetched_body)
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            end
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    return unless supported_context? && expected_type?
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    @uri      = @json['id']
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    @username = @json['preferredUsername']
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    @domain   = Addressable::URI.parse(@uri).normalized_host
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    return unless verified_webfinger?
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    ActivityPub::ProcessAccountService.new.call(@username, @domain, @json)
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  rescue Oj::ParseError
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    nil
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  end
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  private
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  def verified_webfinger?
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    webfinger                            = Goldfinger.finger("acct:#{@username}@#{@domain}")
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    confirmed_username, confirmed_domain = split_acct(webfinger.subject)
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    return webfinger.link('self')&.href == @uri if @username.casecmp(confirmed_username).zero? && @domain.casecmp(confirmed_domain).zero?
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    webfinger                            = Goldfinger.finger("acct:#{confirmed_username}@#{confirmed_domain}")
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    @username, @domain                   = split_acct(webfinger.subject)
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    self_reference                       = webfinger.link('self')
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    return false unless @username.casecmp(confirmed_username).zero? && @domain.casecmp(confirmed_domain).zero?
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    return false if self_reference&.href != @uri
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    true
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  rescue Goldfinger::Error
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    false
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  end
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  def split_acct(acct)
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    acct.gsub(/\Aacct:/, '').split('@')
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  end
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  def supported_context?
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    super(@json)
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  end
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  def expected_type?
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    @json['type'] == 'Person'
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  end
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end
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