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# frozen_string_literal: true
class ResolveAccountService < BaseService
include JsonLdHelper
include DomainControlHelper
include WebfingerHelper
# Find or create an account record for a remote user. When creating,
# look up the user's webfinger and fetch ActivityPub data
# @param [String, Account] uri URI in the username@domain format or account record
# @param [Hash] options
# @option options [Boolean] :redirected Do not follow further Webfinger redirects
# @option options [Boolean] :skip_webfinger Do not attempt to refresh account data
# @return [Account]
def call(uri, options = {})
return if uri.blank?
process_options!(uri, options)
# First of all we want to check if we've got the account
# record with the URI already, and if so, we can exit early
return if domain_not_allowed?(@domain)
@account ||= Account.find_remote(@username, @domain)
return @account if @account&.local? || @domain.nil? || !webfinger_update_due?
# At this point we are in need of a Webfinger query, which may
# yield us a different username/domain through a redirect
process_webfinger!(@uri)
@domain = nil if TagManager.instance.local_domain?(@domain)
# Because the username/domain pair may be different than what
# we already checked, we need to check if we've already got
# the record with that URI, again
return if domain_not_allowed?(@domain)
@account ||= Account.find_remote(@username, @domain)
if gone_from_origin? && not_yet_deleted?
queue_deletion!
return
end
return @account if @account&.local? || gone_from_origin? || !webfinger_update_due?
# Now it is certain, it is definitely a remote account, and it
# either needs to be created, or updated from fresh data
fetch_account!
rescue Webfinger::Error, Oj::ParseError => e
Rails.logger.debug "Webfinger query for #{@uri} failed: #{e}"
nil
end
private
def process_options!(uri, options)
@options = options
if uri.is_a?(Account)
@account = uri
@username = @account.username
@domain = @account.domain
else
@username, @domain = uri.split('@')
end
@domain = begin
if TagManager.instance.local_domain?(@domain)
nil
else
TagManager.instance.normalize_domain(@domain)
end
end
@uri = [@username, @domain].compact.join('@')
end
def process_webfinger!(uri)
@webfinger = webfinger!("acct:#{uri}")
confirmed_username, confirmed_domain = split_acct(@webfinger.subject)
if confirmed_username.casecmp(@username).zero? && confirmed_domain.casecmp(@domain).zero?
@username = confirmed_username
@domain = confirmed_domain
return
end
# Account doesn't match, so it may have been redirected
@webfinger = webfinger!("acct:#{confirmed_username}@#{confirmed_domain}")
@username, @domain = split_acct(@webfinger.subject)
unless confirmed_username.casecmp(@username).zero? && confirmed_domain.casecmp(@domain).zero?
raise Webfinger::RedirectError, "The URI #{uri} tries to hijack #{@username}@#{@domain}"
end
rescue Webfinger::GoneError
@gone = true
end
def split_acct(acct)
acct.gsub(/\Aacct:/, '').split('@')
end
def fetch_account!
return unless activitypub_ready?
RedisLock.acquire(lock_options) do |lock|
if lock.acquired?
@account = ActivityPub::FetchRemoteAccountService.new.call(actor_url)
else
raise Mastodon::RaceConditionError
end
end
@account
end
def webfinger_update_due?
return false if @options[:check_delivery_availability] && !DeliveryFailureTracker.available?(@domain)
@account.nil? || ((!@options[:skip_webfinger] || @account.ostatus?) && @account.possibly_stale?)
end
def activitypub_ready?
['application/activity+json', 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'].include?(@webfinger.link('self', 'type'))
end
def actor_url
@actor_url ||= @webfinger.link('self', 'href')
end
def gone_from_origin?
@gone
end
def not_yet_deleted?
@account.present? && !@account.local?
end
def queue_deletion!
AccountDeletionWorker.perform_async(@account.id, reserve_username: false, skip_activitypub: true)
end
def lock_options
{ redis: Redis.current, key: "resolve:#{@username}@#{@domain}" }
end
end
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