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Fix a check in SYN cache expansion (syncache_expand()) to accept packets that arrive in the receive window instead of just on the left edge of the receive window.

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This is needed for correct behavior when packets are lost or reordered.

PR:	kern/123950
Reviewed by:	andre@, silby@
Reported by:	Yahoo!, Wang Jin
MFC after:	1 week
This commit is contained in:
Stephan Uphoff 2008-06-16 19:56:59 +00:00
parent 8dce5c1bf6
commit 104ac85378
1 changed files with 7 additions and 4 deletions
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11
sys/netinet/tcp_syncache.c
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@ -906,11 +906,14 @@ syncache_expand(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th,
goto failed;
}
/*
* The SEQ must match the received initial receive sequence
* number + 1 (the SYN) because we didn't ACK any data that
* may have come with the SYN.
* The SEQ must fall in the window starting a the received initial receive
* sequence number + 1 (the SYN).
*/
if (th->th_seq != sc->sc_irs + 1 && !TOEPCB_ISSET(sc)) {
if ((SEQ_LEQ(th->th_seq, sc->sc_irs) ||
SEQ_GT(th->th_seq, sc->sc_irs + sc->sc_wnd )) &&
!TOEPCB_ISSET(sc))
{
if ((s = tcp_log_addrs(inc, th, NULL, NULL)))
log(LOG_DEBUG, "%s; %s: SEQ %u != IRS+1 %u, segment "
"rejected\n", s, __func__, th->th_seq, sc->sc_irs);