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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 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 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 accept_node(node, parent)
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{
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const clone = document.importNode(node, false);
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node.hachette_corresponding = clone;
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/*
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* TODO: Stop page's own issues like "Error parsing a meta element's
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* content:" from appearing as extension's errors.
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*/
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parent.hachette_corresponding.appendChild(clone);
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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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if (is_csp_header_name(http_equiv, false))
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meta.content = sanitize_csp_header({value}, policy).value;
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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", csp_rule(policy.nonce));
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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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new_html.replaceWith(old_html);
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}
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if (!is_privileged_url(document.URL)) {
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const reductor =
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(ac, [_, sig, pol]) => ac[0] && ac || [extract_signed(sig, pol), sig];
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const matches = [...document.cookie.matchAll(/hachette-(\w*)=([^;]*)/g)];
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let [policy, signature] = matches.reduce(reductor, []);
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if (!policy || policy.url !== document.URL) {
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console.log("WARNING! Using default policy!!!");
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policy = {allow: false, nonce: gen_nonce()};
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}
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if (signature)
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document.cookie = `hachette-${signature}=; Max-Age=-1;`;
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if (!policy.allow)
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sanitize_document(document, policy);
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handle_page_actions(policy.nonce);
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start_activity_info_server();
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}
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