Block on TLS

JavaScript

export default {
  async fetch(request) {
    try {
      const tlsVersion = request.cf.tlsVersion;
      // Allow only TLS versions 1.2 and 1.3
      if (tlsVersion !== "TLSv1.2" && tlsVersion !== "TLSv1.3") {
        return new Response("Please use TLS version 1.2 or higher.", {
          status: 403,
        });
      }
      return fetch(request);
    } catch (err) {
      console.error(
        "request.cf does not exist in the previewer, only in production",
      );
      return new Response(`Error in workers script ${err.message}`, {
        status: 500,
      });
    }
  },
};

TypeScript

export default {
  async fetch(request): Promise<Response> {
    try {
      const tlsVersion = request.cf.tlsVersion;
      // Allow only TLS versions 1.2 and 1.3
      if (tlsVersion !== "TLSv1.2" && tlsVersion !== "TLSv1.3") {
        return new Response("Please use TLS version 1.2 or higher.", {
          status: 403,
        });
      }
      return fetch(request);
    } catch (err) {
      console.error(
        "request.cf does not exist in the previewer, only in production",
      );
      return new Response(`Error in workers script ${err.message}`, {
        status: 500,
      });
    }
  },
} satisfies ExportedHandler;

Python

from js import Response, fetch

async def on_fetch(request):
    tls_version = request.cf.tlsVersion
    if tls_version not in ("TLSv1.2", "TLSv1.3"):
        return Response.new("Please use TLS version 1.2 or higher.", status=403)
    return fetch(request)