Typescript code to verify if an incoming request's IP address is from OpenAI's CIDR block

valid-chatgpt-ip.ts

function ipToInt(ip: string) {
  return ip.split(".").reduce((acc, octet) => (acc << 8) + parseInt(octet), 0);
}

function isIpInCIDR(ip: string, cidr: string) {
  const [cidrIp, prefixLength] = cidr.split("/");
  const mask = -1 << (32 - parseInt(prefixLength));
  const ipInt = ipToInt(ip);
  const cidrIpInt = ipToInt(cidrIp);

  const networkAddress = cidrIpInt & mask;
  const broadcastAddress = networkAddress | ~mask;

  return ipInt >= networkAddress && ipInt <= broadcastAddress;
}

export default function validChatGPTIp(ip: string) {
  // verify both CIDR blocks from the docs: https://platform.openai.com/docs/plugins/production/ip-egress-ranges
  return (
    isIpInCIDR(ip, "23.102.140.112/28") || isIpInCIDR(ip, "23.98.142.176/28")
  );
}

Thanks for sharing this @steven-tey! 🙏