Why does not extend the `data_end` during re-written the packet

[paulzhn]

When the client send GET to server, the packet only contains the GET abcd. In this example, the data_end - data = 8. So, if we want to re-write the value into the original packet, the packet size should be extended.

However, the packet only seemed to extend with 128 bytes length, but the maximum allowed length is 1500, then if the value is longer then 8, where to write the rest of value?