Haketilo

/**

 * 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 sign_data

 * IMPORT gen_nonce

 * IMPORT is_privileged_url

 * IMPORT mozilla_suppress_scripts

 * IMPORT is_chrome

 * IMPORT is_mozilla

 * IMPORT start_activity_info_server

 * IMPORT modify_on_the_fly

 * 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);

}

function extract_cookie_policy(cookie, min_time)

{

    let best_result = {time: -1};

    let policy = null;

    const extracted_signatures = [];

    for (const match of cookie.matchAll(/hachette-(\w*)=([^;]*)/g)) {

	const new_result = extract_signed(...match.slice(1, 3));

	if (new_result.fail)

	    continue;

	extracted_signatures.push(match[1]);

	if (new_result.time < Math.max(min_time, best_result.time))

	    continue;

	/* This should succeed - it's our self-produced valid JSON. */

	const new_policy = JSON.parse(decodeURIComponent(new_result.data));

	if (new_policy.url !== document.URL)

	    continue;

	best_result = new_result;

	policy = new_policy;

    }

    return [policy, extracted_signatures];

}

function extract_url_policy(url, min_time)

{

    const [base_url, payload, anchor] =

	  /^([^#]*)#?([^#]*)(#?.*)$/.exec(url).splice(1, 4);

    const match = /^hachette_([^_]+)_(.*)$/.exec(payload);

    if (!match)

	return [null, url];

    const result = extract_signed(...match.slice(1, 3));

    if (result.fail)

	return [null, url];

    const original_url = base_url + anchor;

    const policy = result.time < min_time ? null :

	  JSON.parse(decodeURIComponent(result.data));

    return [policy.url === original_url ? policy : null, original_url];

}

function employ_nonhttp_policy(policy)

{

    if (!policy.allow)

	return;

    policy.nonce = gen_nonce();

    const [base_url, target] = /^([^#]*)(#?.*)$/.exec(policy.url).slice(1, 3);

    const encoded_policy = encodeURIComponent(JSON.stringify(policy));

    const payload = "hachette_" +

	  sign_data(encoded_policy, new Date().getTime()).join("_");

    const resulting_url = `${base_url}#${payload}${target}`;

    location.href = resulting_url;

    location.reload();

}

if (!is_privileged_url(document.URL)) {

    let policy_received_callback = () => undefined;

    let policy;

    /* Signature valid for half an hour. */

    const min_time = new Date().getTime() - 1800 * 1000;

    if (/^https?:/.test(document.URL)) {

	let signatures;

	[policy, signatures] = extract_cookie_policy(document.cookie, min_time);

	for (const signature of signatures)

	    document.cookie = `hachette-${signature}=; Max-Age=-1;`;

    } else {

	const scheme = /^([^:]*)/.exec(document.URL)[1];

	const known_scheme = ["file", "ftp"].includes(scheme);

	if (!known_scheme)

	    console.warn(`Unknown url scheme: \`${scheme}'!`);

	let original_url;

	[policy, original_url] = extract_url_policy(document.URL, min_time);

	history.replaceState(null, "", original_url);

	if (known_scheme && !policy)

	    policy_received_callback = employ_nonhttp_policy;

    }

    if (!policy) {

	console.warn("Using default policy!");

	policy = {allow: false, nonce: gen_nonce()};

    }

    handle_page_actions(policy.nonce, policy_received_callback);

    if (!policy.allow) {

	if (is_mozilla) {

	    const script = document.querySelector("script");

	    if (script)

		script.textContent = "throw 'blocked';\n" + script.textContent;

	}

	const old_html = document.documentElement;

	const new_html = document.createElement("html");

	old_html.replaceWith(new_html);

	old_html.hachette_corresponding = new_html;

	const modify_end =

	      modify_on_the_fly(old_html, policy, {node_eater: accept_node});

	document.addEventListener("DOMContentLoaded", modify_end);

    }

    start_activity_info_server();

}