javascript-url-srcdoc-cross-origin-iframe-inheritance-helper.sub.html

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<!DOCTYPE html>

<head>

  <meta charset="utf-8">

  <meta http-equiv="Content-Security-Policy" content="frame-src 'self'">

  <script>

    // The following is the content of a srcdoc iframe. It contains:

    // - a script that catches the frame-src securitypolicyviolation event and

    // forwards the information to the parent,

    // - a cross-origin iframe.

    let doc = `

      <script>

        window.addEventListener("securitypolicyviolation", e => {

          if (e.violatedDirective === "frame-src") {

            window.top.postMessage("frame blocked", "*");

});

      </scr` + `ipt>

      <iframe src="http://{{hosts[alt][]}}:{{ports[http][0]}}/content-security-policy/inheritance/support/postmessage-top.html"></iframe>`;

    doc = doc.replaceAll('"', "\\\'");

    const js_url = "javascript:'<iframe srcdoc=\""+ doc +"\">'";

    window.open(js_url, "_self");

  </script>

</head>