code: function bufferBodyIndexOf (b) {
    for (var i = 0, len = b.length - 3; i < len; i++) {
      if (b[i] === 0x0d && b[i + 1] === 0x0a && b[i + 2] === 0x0d && b[i + 3] === 0x0a) {
        return i + 4
      }
    }
    return -1
  }
docs: /*
  从缓存中找到头部结束标记("\r\n\r\n")的位置