debian-mirror-gitlab/lib/gitlab/database/load_balancing/srv_resolver.rb

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2021-09-04 01:27:46 +05:30
# frozen_string_literal: true
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require 'net/dns'
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module Gitlab
module Database
module LoadBalancing
# Hostnames returned in SRV records cannot sometimes be resolved by a local
# resolver, however, there's a possibility that their A/AAAA records are
# returned as part of the SRV query in the additional section, so we try
# to extract the IPs from there first, failing back to querying the
# hostnames A/AAAA records one by one, using the same resolver that
# queried the SRV record.
class SrvResolver
include Gitlab::Utils::StrongMemoize
attr_reader :resolver, :additional
def initialize(resolver, additional)
@resolver = resolver
@additional = additional
end
def address_for(host)
addresses_from_additional[host] || resolve_host(host)
end
private
def addresses_from_additional
strong_memoize(:addresses_from_additional) do
additional.each_with_object({}) do |rr, h|
h[rr.name] = rr.address if rr.is_a?(Net::DNS::RR::A) || rr.is_a?(Net::DNS::RR::AAAA)
end
end
end
def resolve_host(host)
record = resolver.search(host, Net::DNS::ANY).answer.find do |rr|
rr.is_a?(Net::DNS::RR::A) || rr.is_a?(Net::DNS::RR::AAAA)
end
record&.address
end
end
end
end
end