[lwip-devel] [bug #20779] Keep-Alive and SYNs

[Frédéric Bernon]

Follow-up Comment #3, bug #20779 (project lwip):

If the problem is due to tcp_process's lines you give, I think the the filter
should be done in tcp_input to avoid to "tcp_process" the old pcb. Perhaps do
something like:

if ((flags & TCP_SYN) && (pcb->state != LISTEN)) {
  /* drop SYN packets on non-LISTEN pcb */
  TCP_STATS_INC(tcp.chkerr);
  TCP_STATS_INC(tcp.drop);
  snmp_inc_tcpinerrs();
  pbuf_free(p);
  return;
}

I see that in tcp_in.c, in tcp_input(), lines ~260 (of last cvs head file).

But perhaps a better solution will be to abord the "old" connection? I don't
know if there is any RFC requirements on that point...

Other point, it seems that we should add some "snmp_inc_tcpinerrs();" after
each "TCP_STATS_INC(tcp.drop);", and "TCP_STATS_INC(tcp.drop);" in the "/*
Don't even process incoming broadcasts/multicasts. */" part...


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