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;