Haketilo

/**

 * This file is part of Haketilo.

 *

 * Function: Miscellaneous operations refactored to a separate file.

 *

 * Copyright (C) 2021 Wojtek Kosior

 * Copyright (C) 2021 jahoti

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * As additional permission under GNU GPL version 3 section 7, you

 * may distribute forms of that code without the copy of the GNU

 * GPL normally required by section 4, provided you include this

 * license notice and, in case of non-source distribution, a URL

 * through which recipients can access the Corresponding Source.

 * If you modify file(s) with this exception, you may extend this

 * exception to your version of the file(s), but you are not

 * obligated to do so. If you do not wish to do so, delete this

 * exception statement from your version.

 *

 * As a special exception to the GPL, any HTML file which merely

 * makes function calls to this code, and for that purpose

 * includes it by reference shall be deemed a separate work for

 * copyright law purposes. If you modify this code, you may extend

 * this exception to your version of the code, but you are not

 * obligated to do so. If you do not wish to do so, delete this

 * exception statement from your version.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>.

 *

 * I, Wojtek Kosior, thereby promise not to sue for violation of this file's

 * license. Although I request that you do not make use of this code in a

 * proprietary program, I am not going to enforce this in court.

 */

#FROM common/browser.js      IMPORT browser

#FROM common/stored_types.js IMPORT TYPE_NAME, TYPE_PREFIX

/* uint8_to_hex is a separate function used in cryptographic functions. */

const uint8_to_hex =

      array => [...array].map(b => ("0" + b.toString(16)).slice(-2)).join("");

/*

 * Asynchronously compute hex string representation of a sha256 digest of a

 * UTF-8 string.

 */

async function sha256_async(string) {

    const input_ab = new TextEncoder("utf-8").encode(string);

    const digest_ab = await crypto.subtle.digest("SHA-256", input_ab);

    return uint8_to_hex(new Uint8Array(digest_ab));

}

#EXPORT sha256_async

/*

 * Generate a unique value that can be computed synchronously and is impossible

 * to guess for a malicious website.

 */

function gen_nonce(length=16)

{

    const random_data = new Uint8Array(length);

    crypto.getRandomValues(random_data);

    return uint8_to_hex(random_data);

}

#EXPORT gen_nonce

/* Check if some HTTP header might define CSP rules. */

const csp_header_regex =

      /^\s*(content-security-policy|x-webkit-csp|x-content-security-policy)/i;

#EXPORT csp_header_regex

/*

 * Print item together with type, e.g.

 * nice_name("s", "hello") → "hello (script)"

 */

#EXPORT  (prefix, name) => `${name} (${TYPE_NAME[prefix]})`  AS nice_name

/* Open settings tab with given item's editing already on. */

function open_in_settings(prefix, name)

{

    name = encodeURIComponent(name);

    const url = browser.runtime.getURL("html/options.html#" + prefix + name);

    window.open(url, "_blank");

}

#EXPORT open_in_settings

/*

 * Check if url corresponds to a browser's special page (or a directory index in

 * case of `file://' protocol).

 */

const privileged_reg =

      /^(chrome(-extension)?|moz-extension):\/\/|^about:|^file:\/\/.*\/$/;

#EXPORT  url => privileged_reg.test(url)  AS is_privileged_url

/* Parse a CSP header */

function parse_csp(csp) {

    let directive, directive_array;

    let directives = {};

    for (directive of csp.split(';')) {

	directive = directive.trim();

	if (directive === '')

	    continue;

	directive_array = directive.split(/\s+/);

	directive = directive_array.shift();

	/* The "true" case should never occur; nevertheless... */

	directives[directive] = directive in directives ?

	    directives[directive].concat(directive_array) :

	    directive_array;

    }

    return directives;

}

/* Regexes and objects to use as/in schemas for parse_json_with_schema(). */

const nonempty_string_matcher = /.+/;

const matchers = {

    sha256: /^[0-9a-f]{64}$/,

    nonempty_string: nonempty_string_matcher,

    component: [

	new RegExp(`^[${TYPE_PREFIX.SCRIPT}${TYPE_PREFIX.BAG}]$`),

	nonempty_string_matcher

    ]

};

#EXPORT matchers

/*

 * Facilitates checking if there aren't any keys in object. This does *NOT*

 * account for pathological cases like redefined properties of Object prototype.

 */

function is_object_empty(object)

{

    for (const key in object)

	return false;

    return true;

}

#EXPORT is_object_empty