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--- sys/netinet/tcp_input.c 27 Feb 2005 21:43:54 -0000 1.252.2.14
+++ sys/netinet/tcp_input.c 28 Jun 2005 20:53:10 -0000
@@ -1081,7 +1081,7 @@
* XXX this is traditional behavior, may need to be cleaned up.
*/
tcp_dooptions(tp, &to, optp, optlen, thflags & TH_SYN, th);
- if (thflags & TH_SYN) {
+ if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
if (to.to_flags & TOF_SCALE) {
tp->t_flags |= TF_RCVD_SCALE;
tp->requested_s_scale = to.to_requested_s_scale;
@@ -1816,11 +1816,25 @@
/*
* If last ACK falls within this segment's sequence numbers,
* record its timestamp.
- * NOTE that the test is modified according to the latest
- * proposal of the tcplw@cray.com list (Braden 1993/04/26).
+ * NOTE:
+ * 1) That the test incorporates suggestions from the latest
+ * proposal of the tcplw@cray.com list (Braden 1993/04/26).
+ * 2) That updating only on newer timestamps interferes with
+ * our earlier PAWS tests, so this check should be solely
+ * predicated on the sequence space of this segment.
+ * 3) That we modify the segment boundary check to be
+ * Last.ACK.Sent <= SEG.SEQ + SEG.Len
+ * instead of RFC1323's
+ * Last.ACK.Sent < SEG.SEQ + SEG.Len,
+ * This modified check allows us to overcome RFC1323's
+ * limitations as described in Stevens TCP/IP Illustrated
+ * Vol. 2 p.869. In such cases, we can still calculate the
+ * RTT correctly when RCV.NXT == Last.ACK.Sent.
*/
if ((to.to_flags & TOF_TS) != 0 &&
- SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
+ SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
+ SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
+ ((thflags & (TH_SYN|TH_FIN)) != 0))) {
tp->ts_recent_age = ticks;
tp->ts_recent = to.to_tsval;
}
@@ -2685,6 +2699,12 @@
bcopy((char *)cp + 6,
(char *)&to->to_tsecr, sizeof(to->to_tsecr));
to->to_tsecr = ntohl(to->to_tsecr);
+ /*
+ * If echoed timestamp is later than the current time,
+ * fall back to non RFC1323 RTT calculation.
+ */
+ if ((to->to_tsecr != 0) && TSTMP_GT(to->to_tsecr, ticks))
+ to->to_tsecr = 0;
break;
case TCPOPT_CC:
if (optlen != TCPOLEN_CC)
--- sys/netinet/tcp_seq.h 31 Jan 2005 23:26:36 -0000 1.22.2.1
+++ sys/netinet/tcp_seq.h 29 Jun 2005 08:59:23 -0000
@@ -47,6 +47,7 @@
/* for modulo comparisons of timestamps */
#define TSTMP_LT(a,b) ((int)((a)-(b)) < 0)
+#define TSTMP_GT(a,b) ((int)((a)-(b)) > 0)
#define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0)
/*
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