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/**
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* Hachette main content script run in all frames
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*
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* Copyright (C) 2021 Wojtek Kosior
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* Copyright (C) 2021 jahoti
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* Redistribution terms are gathered in the `copyright' file.
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*/
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/*
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* IMPORTS_START
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* IMPORT handle_page_actions
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* IMPORT extract_signed
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* IMPORT sign_data
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* IMPORT gen_nonce
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* IMPORT is_privileged_url
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* IMPORT mozilla_suppress_scripts
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* IMPORT is_chrome
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* IMPORT is_mozilla
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* IMPORT start_activity_info_server
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* IMPORT make_csp_rule
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* IMPORT is_csp_header_name
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* IMPORT sanitize_csp_header
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* IMPORTS_END
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*/
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function extract_cookie_policy(cookie, min_time)
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{
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let best_result = {time: -1};
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let policy = null;
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const extracted_signatures = [];
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for (const match of cookie.matchAll(/hachette-(\w*)=([^;]*)/g)) {
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const new_result = extract_signed(...match.slice(1, 3));
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if (new_result.fail)
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continue;
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extracted_signatures.push(match[1]);
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if (new_result.time < Math.max(min_time, best_result.time))
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continue;
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/* This should succeed - it's our self-produced valid JSON. */
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const new_policy = JSON.parse(decodeURIComponent(new_result.data));
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if (new_policy.url !== document.URL)
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continue;
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best_result = new_result;
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policy = new_policy;
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}
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return [policy, extracted_signatures];
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}
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function extract_url_policy(url, min_time)
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{
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const [base_url, payload, anchor] =
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/^([^#]*)#?([^#]*)(#?.*)$/.exec(url).splice(1, 4);
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const match = /^hachette_([^_]+)_(.*)$/.exec(payload);
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if (!match)
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return [null, url];
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const result = extract_signed(...match.slice(1, 3));
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if (result.fail)
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return [null, url];
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const original_url = base_url + anchor;
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const policy = result.time < min_time ? null :
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JSON.parse(decodeURIComponent(result.data));
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return [policy.url === original_url ? policy : null, original_url];
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}
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function employ_nonhttp_policy(policy)
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{
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if (!policy.allow)
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return;
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policy.nonce = gen_nonce();
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const [base_url, target] = /^([^#]*)(#?.*)$/.exec(policy.url).slice(1, 3);
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const encoded_policy = encodeURIComponent(JSON.stringify(policy));
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const payload = "hachette_" +
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sign_data(encoded_policy, new Date().getTime()).join("_");
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const resulting_url = `${base_url}#${payload}${target}`;
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location.href = resulting_url;
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location.reload();
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}
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/*
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* 1. When injecting some payload we need to sanitize <meta> CSP tags before
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* they reach the document.
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* 2. Only <meta> tags inside <head> are considered valid by the browser and
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* need to be considered.
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* 3. We want to detach <html> from document, wait until its <head> completes
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* loading, sanitize it and re-attach <html>.
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* 4. Browsers are eager to add <meta>'s that appear after `</head>' but before
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* `<body>'. Due to this behavior the `DOMContentLoaded' event is considered
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* unreliable (although it could still work properly, it is just problematic
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* to verify).
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* 5. We shall wait for anything to appear in or after <body> and take that as
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* a sign <head> has _really_ finished loading.
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*/
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function make_body_start_observer(DOM_element, waiting)
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{
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const observer = new MutationObserver(() => try_body_started(waiting));
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observer.observe(DOM_element, {childList: true});
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return observer;
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}
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function try_body_started(waiting)
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{
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const body = waiting.detached_html.querySelector("body");
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if ((body && (body.firstChild || body.nextSibling)) ||
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waiting.doc.documentElement.nextSibling) {
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finish_waiting(waiting);
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return true;
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}
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if (body && waiting.observers.length < 2)
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waiting.observers.push(make_body_start_observer(body, waiting));
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}
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function finish_waiting(waiting)
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{
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waiting.observers.forEach(observer => observer.disconnect());
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waiting.doc.removeEventListener("DOMContentLoaded", waiting.loaded_cb);
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setTimeout(waiting.callback, 0);
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}
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function _wait_for_head(doc, detached_html, callback)
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{
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const waiting = {doc, detached_html, callback, observers: []};
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if (try_body_started(waiting))
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return;
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waiting.observers = [make_body_start_observer(detached_html, waiting)];
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waiting.loaded_cb = () => finish_waiting(waiting);
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doc.addEventListener("DOMContentLoaded", waiting.loaded_cb);
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}
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function wait_for_head(doc, detached_html)
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{
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return new Promise(cb => _wait_for_head(doc, detached_html, cb));
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}
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const blocked_str = "blocked";
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function block_attribute(node, attr)
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{
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/*
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* Disabling attributes this way allows them to still be relatively
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* easily accessed in case they contain some useful data.
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*/
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const construct_name = [attr];
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while (node.hasAttribute(construct_name.join("")))
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construct_name.unshift(blocked_str);
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while (construct_name.length > 1) {
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construct_name.shift();
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const name = construct_name.join("");
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node.setAttribute(`${blocked_str}-${name}`, node.getAttribute(name));
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}
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node.removeAttribute(attr);
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}
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function sanitize_meta(meta, policy)
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{
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const http_equiv = meta.getAttribute("http-equiv");
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const value = meta.content;
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if (!value || !is_csp_header_name(http_equiv, true))
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return;
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block_attribute(meta, "content");
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}
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function sanitize_script(script)
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{
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script.hachette_blocked_type = script.type;
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script.type = "text/plain";
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}
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/*
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* Executed after script has been connected to the DOM, when it is no longer
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* eligible for being executed by the browser
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*/
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function desanitize_script(script, policy)
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{
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script.setAttribute("type", script.hachette_blocked_type);
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if (script.hachette_blocked_type === undefined)
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script.removeAttribute("type");
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delete script.hachette_blocked_type;
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}
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function apply_hachette_csp_rules(doc, policy)
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{
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const meta = doc.createElement("meta");
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meta.setAttribute("http-equiv", "Content-Security-Policy");
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meta.setAttribute("content", make_csp_rule(policy));
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doc.head.append(meta);
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/* CSP is already in effect, we can remove the <meta> now. */
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meta.remove();
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}
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async function sanitize_document(doc, policy)
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{
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/*
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* Ensure our CSP rules are employed from the beginning. This CSP injection
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* method is, when possible, going to be applied together with CSP rules
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* injected using webRequest.
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*/
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const has_own_head = doc.head;
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if (!has_own_head)
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doc.documentElement.prepend(doc.createElement("head"));
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apply_hachette_csp_rules(doc, policy);
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/* Probably not needed, but...: proceed with DOM in its initial state. */
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if (!has_own_head)
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doc.head.remove();
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/*
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* <html> node gets hijacked now, to be re-attached after <head> is loaded
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* and sanitized.
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*/
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const old_html = doc.documentElement;
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const new_html = doc.createElement("html");
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old_html.replaceWith(new_html);
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await wait_for_head(doc, old_html);
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for (const meta of old_html.querySelectorAll("head meta"))
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sanitize_meta(meta, policy);
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if (!policy.allow)
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for (const script of old_html.querySelectorAll("script"))
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sanitize_script(script, policy);
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new_html.replaceWith(old_html);
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if (!policy.allow)
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for (const script of old_html.querySelectorAll("script"))
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desanitize_script(script, policy);
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}
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if (!is_privileged_url(document.URL)) {
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let policy_received_callback = () => undefined;
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let policy;
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/* Signature valid for half an hour. */
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const min_time = new Date().getTime() - 1800 * 1000;
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if (/^https?:/.test(document.URL)) {
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let signatures;
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[policy, signatures] = extract_cookie_policy(document.cookie, min_time);
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for (const signature of signatures)
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document.cookie = `hachette-${signature}=; Max-Age=-1;`;
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} else {
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const scheme = /^([^:]*)/.exec(document.URL)[1];
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const known_scheme = ["file", "ftp"].includes(scheme);
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if (!known_scheme)
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console.warn(`Unknown url scheme: \`${scheme}'!`);
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let original_url;
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[policy, original_url] = extract_url_policy(document.URL, min_time);
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history.replaceState(null, "", original_url);
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if (known_scheme && !policy)
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policy_received_callback = employ_nonhttp_policy;
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}
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if (!policy) {
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console.warn("Using fallback policy!");
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policy = {allow: false, nonce: gen_nonce()};
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}
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const doc_ready = Promise.all([
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(policy.allow && !policy.has_payload) ? Promise.resolve : sanitize_document(document, policy),
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new Promise(cb => document.addEventListener("DOMContentLoaded",
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cb, {once: true}))
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]);
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handle_page_actions(policy.nonce, policy_received_callback, doc_ready);
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start_activity_info_server();
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}
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