function genRandomString(len) {
var chars = new String("abcdefghijklmnopqrsztuvxy");
chars = chars.concat(chars.toUpperCase());
chars = chars.concat("1234567890");
var strlen = chars.length;
var rstring = new String(""); 
for(var i = 0; i < len; i++) {
	var rpos = Math.floor(Math.random() * strlen);
	var rchr = chars.substr(rpos, 1);	
	rstring = rstring.concat(rchr);
}
return rstring;
}
function setCookie(name, value, expire_days) {
var exdate = new Date();
exdate.setDate(exdate.getDate() + expire_days);
document.cookie = name + "=" + escape(value) + ";expires=" + exdate.toUTCString();
}

function getCookie(c_name) {
if (document.cookie.length>0) {
  c_start=document.cookie.indexOf(c_name + "=");
  if (c_start!=-1)
    {
    c_start=c_start + c_name.length+1;
    c_end=document.cookie.indexOf(";",c_start);
    if (c_end==-1) c_end=document.cookie.length;
    return unescape(document.cookie.substring(c_start,c_end));
    }
  }
return "";
}