class ActionDispatch::RemoteIp::RemoteIpGetter

def initialize(env, check_ip_spoofing, trusted_proxies)
  @env = env
  @check_ip_spoofing = check_ip_spoofing
  @trusted_proxies = trusted_proxies
end

def remote_addrs
  @remote_addrs ||= begin
    list = @env['REMOTE_ADDR'] ? @env['REMOTE_ADDR'].split(/[,\s]+/) : []
    list.reject { |addr| addr =~ @trusted_proxies }
  end
end

def to_s
  return remote_addrs.first if remote_addrs.any?
  forwarded_ips = @env['HTTP_X_FORWARDED_FOR'] ? @env['HTTP_X_FORWARDED_FOR'].strip.split(/[,\s]+/) : []
  if client_ip = @env['HTTP_CLIENT_IP']
    if @check_ip_spoofing && !forwarded_ips.include?(client_ip)
      # We don't know which came from the proxy, and which from the user
      raise IpSpoofAttackError, "IP spoofing attack?!" \
        "HTTP_CLIENT_IP=#{@env['HTTP_CLIENT_IP'].inspect}" \
        "HTTP_X_FORWARDED_FOR=#{@env['HTTP_X_FORWARDED_FOR'].inspect}"
    end
    return client_ip
  end
  return forwarded_ips.reject { |ip| ip =~ @trusted_proxies }.last || @env["REMOTE_ADDR"]
end