Hello,
I have a question regarding the expected behaviour with lwip incoming
TCP packets.
I have a my_tcp_recv_cb() callback that handles incoming TCP packets.
Usually, it just ends with
tcp_recved(pcb, p->tot_len);
pbuf_free(p);
However, if sometimes I do not have enough time or memory to handle the
packet, I would like to tell "do not ack this one, please send it again
later"
According to the doc (http://lwip.wikia.com/wiki/Raw/TCP), I understand
that I should :
-call tcp_recved(pcb, written);//if I was still able to handle
"written" bytes, and in that case obviously "written" is less than
p->tot_len
-do *not* call pbuf_free(p);
-return an error (e.g. ERR_MEM)
" If there are no errors and the callback function returns ERR_OK, then
it is responsible for freeing the pbuf. Otherwise, it must not free the
pbuf so that lwIP core code can store it."
But in that case, it just starts to be a mess. Some packets begin to be
delivered very slowly (1 byte at a time in pbufs!), and it does not seem
to behave as expected.
Meanwhile, the program that sent all the data to the network didn't
notice anything, it has just been informed from its TCP API that
everything was delivered.
Am I doing wrong ? Did I miss something ?
To be comprehensive, here are some options of my lwip instance :
PARAMETER LIBRARY_NAME = lwip202
PARAMETER LIBRARY_VER = 1.1
PARAMETER PROC_INSTANCE = ps7_cortexa9_0
PARAMETER ip_frag_max_mtu = 9000
PARAMETER lwip_dhcp = true
PARAMETER mem_size = 524288
PARAMETER memp_n_pbuf = 1024
PARAMETER memp_n_tcp_seg = 1024
PARAMETER pbuf_pool_bufsize = 9700
PARAMETER tcp_ip_rx_checksum_offload = true
PARAMETER tcp_ip_tx_checksum_offload = true
PARAMETER tcp_mss = 8060
PARAMETER tcp_rx_checksum_offload = true
PARAMETER tcp_snd_buf = 65535
PARAMETER tcp_tx_checksum_offload = true
PARAMETER tcp_wnd = 65535
--
-------------------------------------------
Pierre Chatelier
[email protected]
(+33) 03 80 71 16 16
-------------------------------------------
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