Set security headers

JavaScript

export default {
  async fetch(request) {
    const DEFAULT_SECURITY_HEADERS = {
      /*
    Secure your application with Content-Security-Policy headers.
    Enabling these headers will permit content from a trusted domain and all its subdomains.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
    "Content-Security-Policy": "default-src 'self' example.com *.example.com",
    */
      /*
    You can also set Strict-Transport-Security headers.
    These are not automatically set because your website might get added to Chrome's HSTS preload list.
    Here's the code if you want to apply it:
    "Strict-Transport-Security" : "max-age=63072000; includeSubDomains; preload",
    */
      /*
    Permissions-Policy header provides the ability to allow or deny the use of browser features, such as opting out of FLoC - which you can use below:
    "Permissions-Policy": "interest-cohort=()",
    */
      /*
    X-XSS-Protection header prevents a page from loading if an XSS attack is detected.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-XSS-Protection
    */
      "X-XSS-Protection": "0",
      /*
    X-Frame-Options header prevents click-jacking attacks.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
    */
      "X-Frame-Options": "DENY",
      /*
    X-Content-Type-Options header prevents MIME-sniffing.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
    */
      "X-Content-Type-Options": "nosniff",
      "Referrer-Policy": "strict-origin-when-cross-origin",
      "Cross-Origin-Embedder-Policy": 'require-corp; report-to="default";',
      "Cross-Origin-Opener-Policy": 'same-site; report-to="default";',
      "Cross-Origin-Resource-Policy": "same-site",
    };
    const BLOCKED_HEADERS = [
      "Public-Key-Pins",
      "X-Powered-By",
      "X-AspNet-Version",
    ];

    let response = await fetch(request);
    let newHeaders = new Headers(response.headers);

    const tlsVersion = request.cf.tlsVersion;
    console.log(tlsVersion);
    // This sets the headers for HTML responses:
    if (
      newHeaders.has("Content-Type") &&
      !newHeaders.get("Content-Type").includes("text/html")
    ) {
      return new Response(response.body, {
        status: response.status,
        statusText: response.statusText,
        headers: newHeaders,
      });
    }

    Object.keys(DEFAULT_SECURITY_HEADERS).map((name) => {
      newHeaders.set(name, DEFAULT_SECURITY_HEADERS[name]);
    });

    BLOCKED_HEADERS.forEach((name) => {
      newHeaders.delete(name);
    });

    if (tlsVersion !== "TLSv1.2" && tlsVersion !== "TLSv1.3") {
      return new Response("You need to use TLS version 1.2 or higher.", {
        status: 400,
      });
    } else {
      return new Response(response.body, {
        status: response.status,
        statusText: response.statusText,
        headers: newHeaders,
      });
    }
  },
};

TypeScript

export default {
  async fetch(request): Promise<Response> {
    const DEFAULT_SECURITY_HEADERS = {
      /*
    Secure your application with Content-Security-Policy headers.
    Enabling these headers will permit content from a trusted domain and all its subdomains.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
    "Content-Security-Policy": "default-src 'self' example.com *.example.com",
    */
      /*
    You can also set Strict-Transport-Security headers.
    These are not automatically set because your website might get added to Chrome's HSTS preload list.
    Here's the code if you want to apply it:
    "Strict-Transport-Security" : "max-age=63072000; includeSubDomains; preload",
    */
      /*
    Permissions-Policy header provides the ability to allow or deny the use of browser features, such as opting out of FLoC - which you can use below:
    "Permissions-Policy": "interest-cohort=()",
    */
      /*
    X-XSS-Protection header prevents a page from loading if an XSS attack is detected.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-XSS-Protection
    */
      "X-XSS-Protection": "0",
      /*
    X-Frame-Options header prevents click-jacking attacks.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
    */
      "X-Frame-Options": "DENY",
      /*
    X-Content-Type-Options header prevents MIME-sniffing.
    @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
    */
      "X-Content-Type-Options": "nosniff",
      "Referrer-Policy": "strict-origin-when-cross-origin",
      "Cross-Origin-Embedder-Policy": 'require-corp; report-to="default";',
      "Cross-Origin-Opener-Policy": 'same-site; report-to="default";',
      "Cross-Origin-Resource-Policy": "same-site",
    };
    const BLOCKED_HEADERS = [
      "Public-Key-Pins",
      "X-Powered-By",
      "X-AspNet-Version",
    ];

    let response = await fetch(request);
    let newHeaders = new Headers(response.headers);

    const tlsVersion = request.cf.tlsVersion;
    console.log(tlsVersion);
    // This sets the headers for HTML responses:
    if (
      newHeaders.has("Content-Type") &&
      !newHeaders.get("Content-Type").includes("text/html")
    ) {
      return new Response(response.body, {
        status: response.status,
        statusText: response.statusText,
        headers: newHeaders,
      });
    }

    Object.keys(DEFAULT_SECURITY_HEADERS).map((name) => {
      newHeaders.set(name, DEFAULT_SECURITY_HEADERS[name]);
    });

    BLOCKED_HEADERS.forEach((name) => {
      newHeaders.delete(name);
    });

    if (tlsVersion !== "TLSv1.2" && tlsVersion !== "TLSv1.3") {
      return new Response("You need to use TLS version 1.2 or higher.", {
        status: 400,
      });
    } else {
      return new Response(response.body, {
        status: response.status,
        statusText: response.statusText,
        headers: newHeaders,
      });
    }
  },
} satisfies ExportedHandler;

Python

from js import Response, fetch, Headers

async def on_fetch(request):
    default_security_headers = {
        # Secure your application with Content-Security-Policy headers.
        #Enabling these headers will permit content from a trusted domain and all its subdomains.
        #@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
        "Content-Security-Policy": "default-src 'self' example.com *.example.com",
        #You can also set Strict-Transport-Security headers.
        #These are not automatically set because your website might get added to Chrome's HSTS preload list.
        #Here's the code if you want to apply it:
        "Strict-Transport-Security" : "max-age=63072000; includeSubDomains; preload",
        #Permissions-Policy header provides the ability to allow or deny the use of browser features, such as opting out of FLoC - which you can use below:
        "Permissions-Policy": "interest-cohort=()",
        #X-XSS-Protection header prevents a page from loading if an XSS attack is detected.
        #@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-XSS-Protection
        "X-XSS-Protection": "0",
        #X-Frame-Options header prevents click-jacking attacks.
        #@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
        "X-Frame-Options": "DENY",
        #X-Content-Type-Options header prevents MIME-sniffing.
        #@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
        "X-Content-Type-Options": "nosniff",
        "Referrer-Policy": "strict-origin-when-cross-origin",
        "Cross-Origin-Embedder-Policy": 'require-corp; report-to="default";',
        "Cross-Origin-Opener-Policy": 'same-site; report-to="default";',
        "Cross-Origin-Resource-Policy": "same-site",
    }
    blocked_headers = ["Public-Key-Pins", "X-Powered-By" ,"X-AspNet-Version"]

    res = await fetch(request)
    new_headers = Headers.new(res.headers)

    # This sets the headers for HTML responses
    if "text/html" in new_headers["Content-Type"]:
        return Response.new(res.body, status=res.status, statusText=res.statusText, headers=new_headers)

    for name in default_security_headers:
        new_headers.set(name, default_security_headers[name])

    for name in blocked_headers:
        new_headers.delete(name)

    tls = request.cf.tlsVersion

    if not tls in ("TLSv1.2", "TLSv1.3"):
        return Response.new("You need to use TLS version 1.2 or higher.", status=400)
    return Response.new(res.body, status=res.status, statusText=res.statusText, headers=new_headers)

Rust

use std::collections::HashMap;
use worker::*;

#[event(fetch)]
async fn fetch(req: Request, _env: Env, _ctx: Context) -> Result<Response> {
    let default_security_headers = HashMap::from([
        //Secure your application with Content-Security-Policy headers.
        //Enabling these headers will permit content from a trusted domain and all its subdomains.
        //@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
        (
            "Content-Security-Policy",
            "default-src 'self' example.com *.example.com",
        ),
        //You can also set Strict-Transport-Security headers.
        //These are not automatically set because your website might get added to Chrome's HSTS preload list.
        //Here's the code if you want to apply it:
        (
            "Strict-Transport-Security",
            "max-age=63072000; includeSubDomains; preload",
        ),
        //Permissions-Policy header provides the ability to allow or deny the use of browser features, such as opting out of FLoC - which you can use below:
        ("Permissions-Policy", "interest-cohort=()"),
        //X-XSS-Protection header prevents a page from loading if an XSS attack is detected.
        //@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-XSS-Protection
        ("X-XSS-Protection", "0"),
        //X-Frame-Options header prevents click-jacking attacks.
        //@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
        ("X-Frame-Options", "DENY"),
        //X-Content-Type-Options header prevents MIME-sniffing.
        //@see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
        ("X-Content-Type-Options", "nosniff"),
        ("Referrer-Policy", "strict-origin-when-cross-origin"),
        (
            "Cross-Origin-Embedder-Policy",
            "require-corp; report-to='default';",
        ),
        (
            "Cross-Origin-Opener-Policy",
            "same-site; report-to='default';",
        ),
        ("Cross-Origin-Resource-Policy", "same-site"),
    ]);
    let blocked_headers = ["Public-Key-Pins", "X-Powered-By", "X-AspNet-Version"];
    let tls = req.cf().unwrap().tls_version();
    let res = Fetch::Request(req).send().await?;
    let mut new_headers = res.headers().clone();

    // This sets the headers for HTML responses
    if Some(String::from("text/html")) == new_headers.get("Content-Type")? {
        return Ok(Response::from_body(res.body().clone())?
            .with_headers(new_headers)
            .with_status(res.status_code()));
    }
    for (k, v) in default_security_headers {
        new_headers.set(k, v)?;
    }

    for k in blocked_headers {
        new_headers.delete(k)?;
    }

    if !vec!["TLSv1.2", "TLSv1.3"].contains(&tls.as_str()) {
        return Response::error("You need to use TLS version 1.2 or higher.", 400);
    }
    Ok(Response::from_body(res.body().clone())?
        .with_headers(new_headers)
        .with_status(res.status_code()))
}