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sctp: don't do RTT measurements with cookies

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When receiving a cookie, the receiver does not know whether the
peer retransmitted the COOKIE-ECHO chunk or not. Therefore, don't
do an RTT measurement. It might be much too long.
To overcome this limitation, one could do at least two things:
1. Bundle the INIT-ACK chunk with a HEARTBEAT chunk for doing the
   RTT measurement. But this is not allowed.
2. Add a flag to the COOKIE-ECHO chunk, which indicates that it
   is the initial transmission, and not a retransmission. But
   this requires an RFC.

MFC after:	1 week
This commit is contained in:
Michael Tuexen 2023-03-16 10:45:13 +01:00
parent cee09bda03
commit c91ae48a25
1 changed files with 0 additions and 16 deletions
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16
sys/netinet/sctp_input.c
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@ -1351,7 +1351,6 @@ sctp_process_cookie_existing(struct mbuf *m, int iphlen, int offset,
struct sctp_queued_to_read *sq, *nsq;
struct sctp_nets *net;
struct mbuf *op_err;
struct timeval old;
int init_offset, initack_offset, i;
int retval;
int spec_flag = 0;
@ -1499,16 +1498,7 @@ sctp_process_cookie_existing(struct mbuf *m, int iphlen, int offset,
}
/* notify upper layer */
*notification = SCTP_NOTIFY_ASSOC_UP;
/*
* since we did not send a HB make sure we don't
* double things
*/
old.tv_sec = cookie->time_entered.tv_sec;
old.tv_usec = cookie->time_entered.tv_usec;
net->hb_responded = 1;
sctp_calculate_rto(stcb, asoc, net, &old,
SCTP_RTT_FROM_NON_DATA);
if (stcb->asoc.sctp_autoclose_ticks &&
(sctp_is_feature_on(inp, SCTP_PCB_FLAGS_AUTOCLOSE))) {
sctp_timer_start(SCTP_TIMER_TYPE_AUTOCLOSE,
@ -2204,17 +2194,11 @@ sctp_process_cookie_new(struct mbuf *m, int iphlen, int offset,
(void)SCTP_GETTIME_TIMEVAL(&stcb->asoc.time_entered);
*netp = sctp_findnet(stcb, init_src);
if (*netp != NULL) {
struct timeval old;
/*
* Since we did not send a HB, make sure we don't double
* things.
*/
(*netp)->hb_responded = 1;
/* Calculate the RTT. */
old.tv_sec = cookie->time_entered.tv_sec;
old.tv_usec = cookie->time_entered.tv_usec;
sctp_calculate_rto(stcb, asoc, *netp, &old, SCTP_RTT_FROM_NON_DATA);
}
/* respond with a COOKIE-ACK */
sctp_send_cookie_ack(stcb);