[WIP] reuse chrome cookie for leetcode.com

* inspired by skygragon/leetcode-cli#71

Signed-off-by: Eric Wang <skygragon@gmail.com>

Author: skygragon

plugins/cookie.chrome.js

@@ -0,0 +1,118 @@
+var log = require('../log');
+var Plugin = require('../plugin');
+
+// [Usage]
+//
+// TODO: still WIP
+//
+var plugin = new Plugin(100, 'cookie.chrome', '2017.12.22',
+    'Plugin to reuse Chrome\'s leetcode cookie.',
+    ['keytar', 'sqlite3']);
+
+var Chrome = {};
+
+var ChromeMAC = {
+  db:          process.env.HOME + '/Library/Application Support/Google/Chrome/Default/Cookies',
+  iterations:  1003,
+  getPassword: function(cb) {
+    var keytar = require('keytar');
+    keytar.getPassword('Chrome Safe Storage', 'Chrome').then(cb);
+  }
+};
+
+// TODO: test this
+var ChromeLinux = {
+  db:          process.env.HOME + '/.config/google-chrome/Default/Cookies',
+  iterations:  1,
+  getPassword: function(cb) { cb('peanuts'); }
+};
+
+var ChromeWindows = {
+  // TODO
+};
+
+Object.setPrototypeOf(ChromeMAC, Chrome);
+Object.setPrototypeOf(ChromeLinux, Chrome);
+Object.setPrototypeOf(ChromeWindows, Chrome);
+
+Chrome.getInstance = function() {
+  switch (process.platform) {
+    case 'darwin': return ChromeMAC;
+    case 'linux':  return ChromeLinux;
+    case 'win32':  return ChromeWindows;
+  }
+};
+var my = Chrome.getInstance();
+
+Chrome.decodeCookie = function(cookie, cb) {
+  var crypto = require('crypto');
+  crypto.pbkdf2(my.password, 'saltysalt', my.iterations, 16, 'sha1', function(e, key) {
+    if (e) return cb(e);
+
+    var iv = new Buffer(' '.repeat(16));
+    var decipher = crypto.createDecipheriv('aes-128-cbc', key, iv);
+    decipher.setAutoPadding(false);
+
+    var buf = decipher.update(cookie.slice(3)); // remove prefix "v10" or "v11"
+    var final = decipher.final();
+    final.copy(buf, buf.length - 1);
+
+    var padding = buf[buf.length - 1];
+    if (padding) buf = buf.slice(0, buf.length - padding);
+
+    return cb(null, buf.toString('utf8'));
+  });
+};
+
+Chrome.decodeCookies = function(keys, cb) {
+  if (keys.length === 0) return cb(null, my.cookies);
+
+  var k = keys.pop();
+  var v = my.cookies[k];
+  if (!v) return cb('Not found cookie: ' + k);
+
+  my.decodeCookie(v, function(e, cookie) {
+    my.cookies[k] = cookie;
+    my.decodeCookies(keys, cb);
+  });
+};
+
+var KEYS = ['csrftoken', 'LEETCODE_SESSION'];
+Chrome.getCookies = function(cb) {
+  var sqlite3 = require('sqlite3');
+  var db = new sqlite3.Database(my.db);
+
+  db.serialize(function() {
+    my.cookies = {};
+    var sql = 'select name, encrypted_value from cookies where host_key like "%leetcode.com"';
+    db.each(sql, function(e, x) {
+      if (e) return cb(e);
+      if (KEYS.indexOf(x.name) < 0) return;
+      my.cookies[x.name] = x.encrypted_value;
+    });
+
+    db.close(function() {
+      my.getPassword(function(password) {
+        my.password = password;
+        my.decodeCookies(KEYS, cb);
+      });
+    });
+  });
+};
+
+plugin.signin = function(user, cb) {
+  log.debug('try to copy leetcode cookies from chrome ...');
+  my.getCookies(function(e, cookie) {
+    if (e) {
+      log.error('failed to get cookies: ' + e);
+      return plugin.next.signin(user, cb);
+    }
+
+    log.debug('Successfully copied leetcode cookies!');
+    user.sessionId = cookie.LEETCODE_SESSION;
+    user.sessionCSRF = cookie.csrftoken;
+    return cb(null, user);
+  });
+};
+
+module.exports = plugin;