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/* global update_channels */

/* global pako */

/* global __dirname */

"use strict";

// Determine if we're in the tests. If so, define some necessary components.

if(typeof(window) == "undefined"){

const fs = require('fs');

const WebCrypto = require("node-webcrypto-ossl"),

atob = require("atob"),

btoa = require("btoa"),

encoding = require('text-encoding');

var window = {

crypto: new WebCrypto(),

atob,

btoa

};

var update_channels = Function(fs.readFileSync(__dirname + '/update_channels.js').toString() + "return update_channels;")(),

pako = Function(fs.readFileSync(__dirname + '/../external/pako-1.0.5/pako_inflate.min.js').toString() + "return pako;")(),

TextDecoder = encoding.TextDecoder,

chrome = require("sinon-chrome");

}

(function(exports) {

const util = require('./util');

let store,

background_callback;

// how often we should check for new rulesets

const periodicity = 86400;

// jwk key loaded from keys.js

let imported_keys = {};

for(let update_channel of update_channels){

imported_keys[update_channel.name] = window.crypto.subtle.importKey(

"jwk",

update_channel.jwk,

{

name: "RSA-PSS",

hash: {name: "SHA-256"},

},

false,

["verify"]

);

}

// Determine the time until we should check for new rulesets

async function timeToNextCheck() {

const last_checked = await store.local.get_promise('last-checked', false);

if(last_checked) {

const current_timestamp = Date.now() / 1000;

const secs_since_last_checked = current_timestamp - last_checked;

return Math.max(0, periodicity - secs_since_last_checked);

} else {

return 0;

}

}

// Check for new rulesets. If found, return the timestamp. If not, return false

async function checkForNewRulesets(update_channel) {

let timestamp_result = await fetch(update_channel.update_path_prefix + "/latest-rulesets-timestamp");

if(timestamp_result.status == 200) {

let rulesets_timestamp = Number(await timestamp_result.text());

if((await store.local.get_promise('rulesets-timestamp: ' + update_channel.name, 0)) < rulesets_timestamp){

return rulesets_timestamp;

}

}

return false;

}

// Retrieve the timestamp for when a stored ruleset bundle was published

async function getRulesetTimestamps(){

let timestamp_promises = [];

for(let update_channel of update_channels){

timestamp_promises.push(new Promise(async resolve => {

let timestamp = await store.local.get_promise('rulesets-stored-timestamp: ' + update_channel.name, 0);

resolve([update_channel.name, timestamp]);

}));

}

let timestamps = await Promise.all(timestamp_promises);

return timestamps;

}

// Download and return new rulesets

async function getNewRulesets(rulesets_timestamp, update_channel) {

store.local.set_promise('rulesets-timestamp: ' + update_channel.name, rulesets_timestamp);

let signature_promise = fetch(update_channel.update_path_prefix + "/rulesets-signature." + rulesets_timestamp + ".sha256");

let rulesets_promise = fetch(update_channel.update_path_prefix + "/default.rulesets." + rulesets_timestamp + ".gz");

let responses = await Promise.all([

signature_promise,

rulesets_promise

]);

let resolutions = await Promise.all([

util.slurp(responses[0]),

util.slurp(responses[1])

]);

return {

signature_array_buffer: resolutions[0],

rulesets_array_buffer: resolutions[1]

};

}

// Returns a promise which verifies that the rulesets have a valid EFF

// signature, and if so, stores them and returns true.

// Otherwise, it throws an exception.

function verifyAndStoreNewRulesets(new_rulesets, rulesets_timestamp, update_channel){

return new Promise((resolve, reject) => {

imported_keys[update_channel.name].then(publicKey => {

window.crypto.subtle.verify(

{

name: "RSA-PSS",

saltLength: 32

},

publicKey,

new_rulesets.signature_array_buffer,

new_rulesets.rulesets_array_buffer

).then(async isvalid => {

if(isvalid) {

util.log(util.NOTE, update_channel.name + ': Downloaded ruleset signature checks out. Storing rulesets.');

const rulesets_gz = util.ArrayBufferToString(new_rulesets.rulesets_array_buffer);

const rulesets_byte_array = pako.inflate(rulesets_gz);

const rulesets = new TextDecoder("utf-8").decode(rulesets_byte_array);

const rulesets_json = JSON.parse(rulesets);

if(rulesets_json.timestamp != rulesets_timestamp){

reject(update_channel.name + ': Downloaded ruleset had an incorrect timestamp. This may be an attempted downgrade attack. Aborting.');

} else {

await store.local.set_promise('rulesets: ' + update_channel.name, window.btoa(rulesets_gz));

resolve(true);

}

} else {

reject(update_channel.name + ': Downloaded ruleset signature is invalid. Aborting.');

}

}).catch(() => {

reject(update_channel.name + ': Downloaded ruleset signature could not be verified. Aborting.');

});

}).catch(() => {

reject(update_channel.name + ': Could not import key. Aborting.');

});

});

}

// Unzip and apply the rulesets we have stored.

async function applyStoredRulesets(rulesets_obj){

let rulesets_promises = [];

for(let update_channel of update_channels){

rulesets_promises.push(new Promise(resolve => {

const key = 'rulesets: ' + update_channel.name

chrome.storage.local.get(key, root => {

if(root[key]){

util.log(util.NOTE, update_channel.name + ': Applying stored rulesets.');

const rulesets_gz = window.atob(root[key]);

const rulesets_byte_array = pako.inflate(rulesets_gz);

const rulesets = new TextDecoder("utf-8").decode(rulesets_byte_array);

const rulesets_json = JSON.parse(rulesets);

resolve(rulesets_json);

} else {

resolve();

}

});

}));

}

const rulesets_jsons = await Promise.all(rulesets_promises);

if(rulesets_jsons.join("").length > 0){

for(let rulesets_json of rulesets_jsons){

rulesets_obj.addFromJson(rulesets_json.rulesets);

}

} else {

rulesets_obj.addFromJson(util.loadExtensionFile('rules/default.rulesets', 'json'));

}

}

// basic workflow for periodic checks

async function performCheck() {

util.log(util.NOTE, 'Checking for new rulesets.');

const current_timestamp = Date.now() / 1000;

store.local.set_promise('last-checked', current_timestamp);

let num_updates = 0;

for(let update_channel of update_channels){

let new_rulesets_timestamp = await checkForNewRulesets(update_channel);

if(new_rulesets_timestamp){

util.log(util.NOTE, update_channel.name + ': A new ruleset bundle has been released. Downloading now.');

let new_rulesets = await getNewRulesets(new_rulesets_timestamp, update_channel);

try{

await verifyAndStoreNewRulesets(new_rulesets, new_rulesets_timestamp, update_channel);

store.local.set_promise('rulesets-stored-timestamp: ' + update_channel.name, new_rulesets_timestamp);

num_updates++;

} catch(err) {

util.log(util.WARN, update_channel.name + ': ' + err);

}

}

}

if(num_updates > 0){

background_callback();

}

};

chrome.storage.onChanged.addListener(async function(changes, areaName) {

if (areaName === 'sync' || areaName === 'local') {

if ('autoUpdateRulesets' in changes) {

if (changes.autoUpdateRulesets.newValue) {

await createTimer();

} else {

destroyTimer();

}

}

}

});

let initialCheck,

subsequentChecks;

async function createTimer(){

const time_to_next_check = await timeToNextCheck();

initialCheck = setTimeout(() => {

performCheck();

subsequentChecks = setInterval(performCheck, periodicity * 1000);

}, time_to_next_check * 1000);

}

function destroyTimer(){

if (initialCheck) {

clearTimeout(initialCheck);

}

if (subsequentChecks) {

clearInterval(subsequentChecks);

}

}

async function initialize(store_param, cb){

store = store_param;

background_callback = cb;

if (await store.get_promise('autoUpdateRulesets', true)) {

await createTimer();

}

}

Object.assign(exports, {

applyStoredRulesets,

initialize,

getRulesetTimestamps

});

})(typeof exports == 'undefined' ? require.scopes.update = {} : exports);