PAC that uses a white list

proxy-with-white-list.pac

/*global isPlainHostName, isInNet*/
var proxy = "SOCKS5 127.0.0.1:9999; SOCKS 127.0.0.1:9999; DIRECT";
var noProxy = "DIRECT";

var localhosts = [
  ['192.168.0.0', '255.255.0.0'],
  ['10.0.0.0', '255.0.0.0'],
  ['172.0.0.0', '255.0.0.0'],
  ['127.0.0.0', '255.255.255.0']
];

var gi, whiteListed = {}, whiteList = [
  "alipay.com",
  "alipayobjects.com",
  "baidu.com",
  "com.cn",
  "douban.com",
  "edu.cn",
  "feidee.com",
  "icast.cn",
  "kandian.com",
  "mmcdn.cn",
  "mmstat.com",
  "renren.com",
  "sinaapp.com",
  "sinaimg.cn",
  "sinajs.cn",
  "tanx.com",
  "taobao.com",
  "taobaocdn.com",
  "tbcdn.cn",
  "v2ex.com",
  "weibo.com"
];

for (gi = 0; gi < whiteList.length; gi += 1) { whiteListed[whiteList[gi]] = true; }

function isLocal(host) {
  var i, ip, netmask;
  if (isPlainHostName(host)) { return true; }

  for (i = 0; i < localhosts.length; i++) {
    ip = localhosts[i][0];
    netmask = localhosts[i][1];
    if (isInNet(host, ip, netmask)) { return true; }
  }

  return false;
}

function hostToDomain(host) {
  var dotpos = host.lastIndexOf(".");
  if (dotpos === -1) { return host; }

  // Find the second last dot
  dotpos = host.lastIndexOf(".", dotpos - 1);
  if (dotpos === -1) { return host; }

  return host.substring(dotpos + 1);
}

function FindProxyForURL(url, host) {
  if (isLocal(host)) { return noProxy; }
  return (whiteListed[hostToDomain(host)] ? noProxy : proxy);
}