code: function findBody(data) {
  	var i = data.length;
  	while (i-- && i>10) { //10都算少的了
  		if (data[i]===0x0a && data[i-2]===0x0a &&
  			data[i-1]===0x0d && data[i-3]===0x0d) {
  			return i + 1;
  		}
  	}
  	return -1;
  }
docs: '\r\n\r\n'分开head和body