diff options
| author | Garrett Wollman <wollman@FreeBSD.org> | 1995-09-20 21:00:59 +0000 |
|---|---|---|
| committer | Garrett Wollman <wollman@FreeBSD.org> | 1995-09-20 21:00:59 +0000 |
| commit | f138387af128d8bedcdc3ff4a6a7fcba7ba1d845 (patch) | |
| tree | 572521b669715309966bebc91e904cbbebae377c /sys/netinet/tcp_output.c | |
| parent | 2eeab93993bcb11d8e9cbf5c9cc203d0321299dc (diff) | |
| download | src-f138387af128d8bedcdc3ff4a6a7fcba7ba1d845.tar.gz src-f138387af128d8bedcdc3ff4a6a7fcba7ba1d845.zip | |
Add support in TCP for Path MTU discovery. This is highly experimental
and gated on `options MTUDISC' in the source. It is also practically
untested becausse (sniff!) I don't have easy access to a network with
an MTU of less than an Ethernet. If you have a small MTU network,
please try it and tell me if it works!
Notes
Notes:
svn path=/head/; revision=10930
Diffstat (limited to 'sys/netinet/tcp_output.c')
| -rw-r--r-- | sys/netinet/tcp_output.c | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c index 6c7ccd18eb21..f5500ee98123 100644 --- a/sys/netinet/tcp_output.c +++ b/sys/netinet/tcp_output.c @@ -31,7 +31,7 @@ * SUCH DAMAGE. * * @(#)tcp_output.c 8.3 (Berkeley) 12/30/93 - * $Id: tcp_output.c,v 1.11 1995/05/30 08:09:56 rgrimes Exp $ + * $Id: tcp_output.c,v 1.12 1995/09/13 17:36:31 wollman Exp $ */ #include <sys/param.h> @@ -661,16 +661,28 @@ send: else #endif { +#ifdef MTUDISC + struct rtentry *rt; +#endif ((struct ip *)ti)->ip_len = m->m_pkthdr.len; ((struct ip *)ti)->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; /* XXX */ ((struct ip *)ti)->ip_tos = tp->t_inpcb->inp_ip.ip_tos; /* XXX */ -#if BSD >= 43 +#ifdef MTUDISC + /* + * See if we should do MTU discovery. We do it only if the following + * are true: + * 1) we have a valid route to the destination + * 2) the MTU is not locked (if it is, then discovery has been + * disabled) + */ + if ((rt = tp->t_inpcb->inp_route.ro_rt) + && rt->rt_flags & RTF_UP + && !(rt->rt_rmx.rmx_locks & RTV_MTU)) { + ((struct ip *)ti)->ip_off |= IP_DF; + } +#endif /* MTUDISC */ error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route, so->so_options & SO_DONTROUTE, 0); -#else - error = ip_output(m, (struct mbuf *)0, &tp->t_inpcb->inp_route, - so->so_options & SO_DONTROUTE); -#endif } if (error) { out: |