Re: [lwip-users] howto put tcp packet together

[Bernhard 'Gustl' Bauer]

address@hidden schrieb:
> Data gets parted in 2 ways:
> - the remote host may split the data in multiple network packets

This is what happens.

> - lwIP may split a received packet into multiple pbufs
>
> There is however nothing unsorted. I.e. the pbufs you receive hold the 
> data in exactly the same order as the remote host sent it. If you don't 
> get the full data in the first call to your receive callback (be sure to 
> check all pbufs you have been passed: check the ->next pointers until 
> NULL), you can just hold on to these pbufs (don't free them yet) and 
> process them all together later when the receive callback is called again.

pbuf is large enough to contain one network packet. So this is not a 
problem.

> The number of packets is not known in advance (as the remote host 
> creates them as it likes); a counter that specifies the order is not 
> needed as they are always *in order*. Basically, you get one call to the 
> receive callback for every packet received. To get an overview over 
> these packets, a network sniffer like wireshark is always interesting.

A wireshark file is attached. My lwip does only get callbacks for 
packets no. 4, 13, 24, 35, ... Packets no. 14, 25, 36, ... don't 
generate any callbacks. How can I get the data in these packets? Btw 
pcb->next and pbuf->next are always 0!

TCP says the network packets may be out of order. There is a sequence 
number to sort them. Does LWIP take care of this?

TIA

Gustl

testsplit.pcap
Description: Binary data