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/**
* Hachette main content script run in all frames
*
* Copyright (C) 2021 Wojtek Kosior
* Copyright (C) 2021 jahoti
* Redistribution terms are gathered in the `copyright' file.
*/
/*
* IMPORTS_START
* IMPORT handle_page_actions
* IMPORT extract_signed
* IMPORT gen_nonce
* IMPORT is_privileged_url
* IMPORT mozilla_suppress_scripts
* IMPORT is_chrome
* IMPORT is_mozilla
* IMPORT start_activity_info_server
* IMPORT csp_rule
* IMPORT is_csp_header_name
* IMPORT sanitize_csp_header
* IMPORTS_END
*/
function accept_node(node, parent)
{
const clone = document.importNode(node, false);
node.hachette_corresponding = clone;
/*
* TODO: Stop page's own issues like "Error parsing a meta element's
* content:" from appearing as extension's errors.
*/
parent.hachette_corresponding.appendChild(clone);
}
/*
* 1. When injecting some payload we need to sanitize <meta> CSP tags before
* they reach the document.
* 2. Only <meta> tags inside <head> are considered valid by the browser and
* need to be considered.
* 3. We want to detach <html> from document, wait until its <head> completes
* loading, sanitize it and re-attach <html>.
* 4. Browsers are eager to add <meta>'s that appear after `</head>' but before
* `<body>'. Due to this behavior the `DOMContentLoaded' event is considered
* unreliable (although it could still work properly, it is just problematic
* to verify).
* 5. We shall wait for anything to appear in or after <body> and take that as
* a sign <head> has _really_ finished loading.
*/
function make_body_start_observer(DOM_element, waiting)
{
const observer = new MutationObserver(() => try_body_started(waiting));
observer.observe(DOM_element, {childList: true});
return observer;
}
function try_body_started(waiting)
{
const body = waiting.detached_html.querySelector("body");
if ((body && (body.firstChild || body.nextSibling)) ||
waiting.doc.documentElement.nextSibling) {
finish_waiting(waiting);
return true;
}
if (body && waiting.observers.length < 2)
waiting.observers.push(make_body_start_observer(body, waiting));
}
function finish_waiting(waiting)
{
waiting.observers.forEach(observer => observer.disconnect());
waiting.doc.removeEventListener("DOMContentLoaded", waiting.loaded_cb);
setTimeout(waiting.callback, 0);
}
function _wait_for_head(doc, detached_html, callback)
{
const waiting = {doc, detached_html, callback, observers: []};
if (try_body_started(waiting))
return;
waiting.observers = [make_body_start_observer(detached_html, waiting)];
waiting.loaded_cb = () => finish_waiting(waiting);
doc.addEventListener("DOMContentLoaded", waiting.loaded_cb);
}
function wait_for_head(doc, detached_html)
{
return new Promise(cb => _wait_for_head(doc, detached_html, cb));
}
const blocked_str = "blocked";
function block_attribute(node, attr)
{
/*
* Disabling attributes this way allows them to still be relatively
* easily accessed in case they contain some useful data.
*/
const construct_name = [attr];
while (node.hasAttribute(construct_name.join("")))
construct_name.unshift(blocked_str);
while (construct_name.length > 1) {
construct_name.shift();
const name = construct_name.join("");
node.setAttribute(`${blocked_str}-${name}`, node.getAttribute(name));
}
node.removeAttribute(attr);
}
function sanitize_meta(meta, policy)
{
const http_equiv = meta.getAttribute("http-equiv");
const value = meta.content;
if (!value || !is_csp_header_name(http_equiv, true))
return;
block_attribute(meta, "content");
if (is_csp_header_name(http_equiv, false))
meta.content = sanitize_csp_header({value}, policy).value;
}
function apply_hachette_csp_rules(doc, policy)
{
const meta = doc.createElement("meta");
meta.setAttribute("http-equiv", "Content-Security-Policy");
meta.setAttribute("content", csp_rule(policy.nonce));
doc.head.append(meta);
/* CSP is already in effect, we can remove the <meta> now. */
meta.remove();
}
async function sanitize_document(doc, policy)
{
/*
* Ensure our CSP rules are employed from the beginning. This CSP injection
* method is, when possible, going to be applied together with CSP rules
* injected using webRequest.
*/
const has_own_head = doc.head;
if (!has_own_head)
doc.documentElement.prepend(doc.createElement("head"));
apply_hachette_csp_rules(doc, policy);
/* Probably not needed, but...: proceed with DOM in its initial state. */
if (!has_own_head)
doc.head.remove();
/*
* <html> node gets hijacked now, to be re-attached after <head> is loaded
* and sanitized.
*/
const old_html = doc.documentElement;
const new_html = doc.createElement("html");
old_html.replaceWith(new_html);
await wait_for_head(doc, old_html);
for (const meta of old_html.querySelectorAll("head meta"))
sanitize_meta(meta, policy);
new_html.replaceWith(old_html);
}
if (!is_privileged_url(document.URL)) {
const reductor =
(ac, [_, sig, pol]) => ac[0] && ac || [extract_signed(sig, pol), sig];
const matches = [...document.cookie.matchAll(/hachette-(\w*)=([^;]*)/g)];
let [policy, signature] = matches.reduce(reductor, []);
if (!policy || policy.url !== document.URL) {
console.log("WARNING! Using default policy!!!");
policy = {allow: false, nonce: gen_nonce()};
}
if (signature)
document.cookie = `hachette-${signature}=; Max-Age=-1;`;
if (!policy.allow)
sanitize_document(document, policy);
handle_page_actions(policy.nonce);
start_activity_info_server();
}
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