Date: Thu, 24 Dec 2015 15:39:34 +0900 From: Yongmin Cho <yongmincho82@gmail.com> To: freebsd-net@freebsd.org Subject: tcp keep-alive message sent without timestamp option Message-ID: <20151224063933.GB10898@yongmincho-All-Series>
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Hi, all.
I have checked tcp keep-alive in freebsd head.
According to RFC7323, tcp timestamp option must be sent with
keep-alive packet after timestamp option has been negotiated.
So I have tested this on linux-3.13.0.
tcp keep-alive message is sent with timestamp option on linux-3.13.0.
But on freebsd head, tcp keep-alive packet is sent without timestamp option
after negotiated. So I made patch file based on freebsd head.
Please check this patch file. any feedback will be welcome.
Thank you in advance for your answers!
According in RFC7323:
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.
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Content-Disposition: attachment; filename="tcp_subr.diff"
Index: sys/netinet/tcp_subr.c
===================================================================
--- sys/netinet/tcp_subr.c (revision 292681)
+++ sys/netinet/tcp_subr.c (working copy)
@@ -835,7 +835,7 @@ void
tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
tcp_seq ack, tcp_seq seq, int flags)
{
- int tlen;
+ int tlen, optlen = 0;
int win = 0;
struct ip *ip;
struct tcphdr *nth;
@@ -845,6 +845,7 @@ tcp_respond(struct tcpcb *tp, void *ipgen, struct
#endif /* INET6 */
int ipflags = 0;
struct inpcb *inp;
+ struct tcpopt to;
KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
@@ -943,6 +944,17 @@ tcp_respond(struct tcpcb *tp, void *ipgen, struct
ip->ip_off |= htons(IP_DF);
}
#endif
+ if (tp != NULL) {
+ to.to_flags = 0;
+ if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
+ (TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
+ to.to_flags |= TOF_TS;
+ to.to_tsval = tcp_ts_getticks() + tp->ts_offset;
+ to.to_tsecr = tp->ts_recent;
+ tlen += optlen = tcp_addoptions(&to,
+ (u_char *)(nth + 1));
+ }
+ }
m->m_len = tlen;
m->m_pkthdr.len = tlen;
m->m_pkthdr.rcvif = NULL;
@@ -965,7 +977,7 @@ tcp_respond(struct tcpcb *tp, void *ipgen, struct
nth->th_seq = htonl(seq);
nth->th_ack = htonl(ack);
nth->th_x2 = 0;
- nth->th_off = sizeof (struct tcphdr) >> 2;
+ nth->th_off = (sizeof (struct tcphdr) + optlen) >> 2;
nth->th_flags = flags;
if (tp != NULL)
nth->th_win = htons((u_short) (win >> tp->rcv_scale));
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