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/**
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* Myext miscellaneous operations refactored to a separate file
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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 sha256
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* IMPORT browser
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* IMPORT is_chrome
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* IMPORT TYPE_NAME
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* IMPORTS_END
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*/
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/* Generate a random base64-encoded 128-bit sequence */
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function gen_nonce()
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{
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let randomData = new Uint8Array(16);
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crypto.getRandomValues(randomData);
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return btoa(String.fromCharCode.apply(null, randomData));
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}
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/*
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* generating unique, per-site value that can be computed synchronously
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* and is impossible to guess for a malicious website
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*/
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function gen_unique(url)
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{
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return sha256(get_secure_salt() + url);
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}
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function get_secure_salt()
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{
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if (is_chrome)
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return browser.runtime.getManifest().key.substring(0, 50);
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else
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return browser.runtime.getURL("dummy");
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}
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/*
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* stripping url from query and target (everything after `#' or `?'
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* gets removed)
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*/
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function url_item(url)
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{
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let url_re = /^([^?#]*).*$/;
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let match = url_re.exec(url);
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return match[1];
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}
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/*
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* Assume a url like: https://example.com/green?illuminati=confirmed#tinky#winky
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* This function will make it into an object like:
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* {
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* "base_url" : "https://example.com/green?illuminati=confirmed",
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* "target" : "#tinky",
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* "target2" : "#winky"
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* }
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* In case url doesn't have 2 #'s, target2 and target can be set to undefined.
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*/
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function url_extract_target(url)
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{
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let url_re = /^([^#]*)((#[^#]*)(#.*)?)?$/;
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let match = url_re.exec(url);
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return {
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base_url : match[1],
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target : match[3],
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target2 : match[4]
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};
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}
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/* csp rule that blocks all scripts except for those injected by us */
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function csp_rule(nonce)
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{
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let rule = `script-src 'nonce-${nonce}';`;
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if (is_chrome)
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rule += `script-src-elem 'nonce-${nonce}';`;
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return rule;
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}
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/*
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* Print item together with type, e.g.
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* nice_name("s", "hello") → "hello (script)"
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*/
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function nice_name(prefix, name)
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{
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return `${name} (${TYPE_NAME[prefix]})`;
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}
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/* Open settings tab with given item's editing already on. */
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function open_in_settings(prefix, name)
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{
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name = encodeURIComponent(name);
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const url = browser.runtime.getURL("html/options.html#" + prefix + name);
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window.open(url, "_blank");
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}
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/* Check if url corresponds to a browser's special page */
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function is_privileged_url(url)
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{
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return !!/^(chrome(-extension)?|moz-extension):\/\/|^about:/i.exec(url);
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}
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/* Sign a given policy for a given time */
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function sign_policy(policy, now, hours_offset) {
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let time = Math.floor(now / 3600000) + (hours_offset || 0);
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return gen_unique(time + policy);
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}
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/* Extract any policy present in the URL */
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function url_extract_policy(url)
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{
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const targets = url_extract_target(url);
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if (!targets.target)
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return targets;
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/* %7B -> { */
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const index = targets.target.indexOf('%7B');
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if (index === -1)
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return targets;
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const now = new Date();
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const sig = targets.target.substring(1, index);
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const policy = targets.target.substring(index);
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if (
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sig !== sign_policy(policy, now) &&
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sig !== sign_policy(policy, now, -1) &&
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sig !== sign_policy(policy, now, 1)
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)
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return targets;
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try {
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targets.policy = JSON.parse(decodeURIComponent(policy));
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targets.current = targets.policy.base_url === targets.base_url;
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} catch (e) {
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/* TODO what should happen here? */
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}
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return targets;
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}
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/*
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* EXPORTS_START
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* EXPORT gen_nonce
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* EXPORT gen_unique
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* EXPORT url_item
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* EXPORT url_extract_target
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* EXPORT url_extract_policy
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* EXPORT sign_policy
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* EXPORT csp_rule
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* EXPORT nice_name
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* EXPORT open_in_settings
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* EXPORT is_privileged_url
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* EXPORTS_END
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*/
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