On Tue, Apr 14, 2015 at 22:08 +0300, Lauri Tirkkonen wrote:
> On Tue, Apr 14 2015 20:40:58 +0200, Mike Belopuhov wrote:
> > According to 3.2 in RFC 7323:
> >
> > Once TSopt has been successfully negotiated, that is both <SYN> and
> > <SYN,ACK> contain TSopt, the TSopt MUST be sent in every non-<RST>
> > segment for the duration of the connection, and SHOULD be sent in an
> > <RST> segment (see Section 5.2 for details). The TCP SHOULD remember
> > this state by setting a flag, referred to as Snd.TS.OK, to one. If a
> > non-<RST> segment is received without a TSopt, a TCP SHOULD silently
> > drop the segment. A TCP MUST NOT abort a TCP connection because any
> > segment lacks an expected TSopt.
>
> Thank you, I somehow missed the existence of this RFC.
>
Does anyone else want to comment on this?
> > I had a stab at adding timestamp support to tcp_respond but couldn't
> > test yet. If you feel like giving it a try, please be my guest.
>
> With your patch, I confirm that timestamps are present on keep-alive
> messages.
>
The patch needs a small (but crucial) amendment: tcp pcb can be NULL...
diff --git sys/netinet/tcp_subr.c sys/netinet/tcp_subr.c
index c8c8e77..6f17af0 100644
--- sys/netinet/tcp_subr.c
+++ sys/netinet/tcp_subr.c
@@ -295,13 +295,10 @@ tcp_template(tp)
* attached mbufs.
*
* In any case the ack and sequence number of the transmitted
* segment are as specified by the parameters.
*/
-#ifdef INET6
-/* This function looks hairy, because it was so IPv4-dependent. */
-#endif /* INET6 */
void
tcp_respond(struct tcpcb *tp, caddr_t template, struct tcphdr *th0,
tcp_seq ack, tcp_seq seq, int flags, u_int rtableid)
{
int tlen;
@@ -370,14 +367,10 @@ tcp_respond(struct tcpcb *tp, caddr_t template, struct
tcphdr *th0,
xchg(th->th_dport, th->th_sport, u_int16_t);
else
flags = TH_ACK;
#undef xchg
- m->m_len = tlen;
- m->m_pkthdr.len = tlen;
- m->m_pkthdr.rcvif = (struct ifnet *) 0;
- m->m_pkthdr.csum_flags |= M_TCP_CSUM_OUT;
th->th_seq = htonl(seq);
th->th_ack = htonl(ack);
th->th_x2 = 0;
th->th_off = sizeof (struct tcphdr) >> 2;
th->th_flags = flags;
@@ -386,10 +379,26 @@ tcp_respond(struct tcpcb *tp, caddr_t template, struct
tcphdr *th0,
if (win > TCP_MAXWIN)
win = TCP_MAXWIN;
th->th_win = htons((u_int16_t)win);
th->th_urp = 0;
+ if (tp && (tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
+ (flags & TH_RST) == 0 && (tp->t_flags & TF_RCVD_TSTMP)) {
+ u_int32_t *lp = (u_int32_t *)(th + 1);
+ /* Form timestamp option as shown in appendix A of RFC 1323. */
+ *lp++ = htonl(TCPOPT_TSTAMP_HDR);
+ *lp++ = htonl(tcp_now + tp->ts_modulate);
+ *lp = htonl(tp->ts_recent);
+ tlen += TCPOLEN_TSTAMP_APPA;
+ th->th_off = (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_APPA) >> 2;
+ }
+
+ m->m_len = tlen;
+ m->m_pkthdr.len = tlen;
+ m->m_pkthdr.rcvif = (struct ifnet *) 0;
+ m->m_pkthdr.csum_flags |= M_TCP_CSUM_OUT;
+
/* force routing table */
if (tp)
m->m_pkthdr.ph_rtableid = tp->t_inpcb->inp_rtableid;
else
m->m_pkthdr.ph_rtableid = rtableid;
