class Gem::RemoteFetcher

def api_endpoint(uri)
  host = uri.host
  begin
    res = @dns.getresource "_rubygems._tcp.#{host}",
                           Resolv::DNS::Resource::IN::SRV
  rescue Resolv::ResolvError => e
    verbose "Getting SRV record failed: #{e}"
    uri
  else
    target = res.target.to_s.strip
    if /\.#{Regexp.quote(host)}\z/ =~ target
      return URI.parse "#{uri.scheme}://#{target}#{uri.path}"
    end
    uri
  end
end