[lwip-users] tcp_write problem after the first transmission

[Daniel Berenguer]

I'm trying to send a bunch of TCP packets using the raw API but
tcp_write is returning -1 (out of memory) after the 8th packet.

for (i=0 ; i<20 ; i++)
{
    strcpy(buffer, "holaaa");
    res = tcp_write(pcb, buffer, 7, 0);
    tcp_output(pcb);
}

I've used many variants of the above code (with delays, w/o
tcp_output, ...) but the problem is always there. The first packet is
sent immediately after the first tcp_write but then, tcp_write just
pushes the packets into the sending queue. TCP_SND_QUEUELEN is set to
8 so once the TX queue gets overflowed tcp_write starts returning -1
and the contents of the queue is finally sent (only 7 packets of 20
though).

Any idea?

Thanks.