diff options
| author | wollman <wollman@FreeBSD.org> | 1995-12-20 17:42:28 +0000 |
|---|---|---|
| committer | wollman <wollman@FreeBSD.org> | 1995-12-20 17:42:28 +0000 |
| commit | 901107a3b58846b2b2979e213e685b4dfb93158d (patch) | |
| tree | a414c45c8283835c7bec3b4312a2dde2b29c03b9 /sys | |
| parent | 44136d3b306ae79a8aa75bd27322c56cbabf7f0e (diff) | |
| download | FreeBSD-src-901107a3b58846b2b2979e213e685b4dfb93158d.zip FreeBSD-src-901107a3b58846b2b2979e213e685b4dfb93158d.tar.gz | |
Fix a nagging divide-by-zero error resulting from the MTU discovery code
getting triggered at a bad time.
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/netinet/tcp_subr.c | 22 | ||||
| -rw-r--r-- | sys/netinet/tcp_timewait.c | 22 |
2 files changed, 40 insertions, 4 deletions
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c index c41e84c..ee61df3 100644 --- a/sys/netinet/tcp_subr.c +++ b/sys/netinet/tcp_subr.c @@ -31,7 +31,7 @@ * SUCH DAMAGE. * * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 - * $Id: tcp_subr.c,v 1.23 1995/12/05 17:46:43 wollman Exp $ + * $Id: tcp_subr.c,v 1.24 1995/12/16 02:14:19 bde Exp $ */ #include <sys/param.h> @@ -513,7 +513,25 @@ tcp_mtudisc(inp, errno) taop = rmx_taop(rt->rt_rmx); offered = taop->tao_mssopt; mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); - mss = min(mss, offered); + if (offered) + mss = min(mss, offered); + /* + * XXX - The above conditional probably violates the TCP + * spec. The problem is that, since we don't know the + * other end's MSS, we are supposed to use a conservative + * default. But, if we do that, then MTU discovery will + * never actually take place, because the conservative + * default is much less than the MTUs typically seen + * on the Internet today. For the moment, we'll sweep + * this under the carpet. + * + * The conservative default might not actually be a problem + * if the only case this occurs is when sending an initial + * SYN with options and data to a host we've never talked + * to before. Then, they will reply with an MSS value which + * will get recorded and the new parameters should get + * recomputed. For Further Study. + */ if (tp->t_maxopd <= mss) return; tp->t_maxopd = mss; diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c index c41e84c..ee61df3 100644 --- a/sys/netinet/tcp_timewait.c +++ b/sys/netinet/tcp_timewait.c @@ -31,7 +31,7 @@ * SUCH DAMAGE. * * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 - * $Id: tcp_subr.c,v 1.23 1995/12/05 17:46:43 wollman Exp $ + * $Id: tcp_subr.c,v 1.24 1995/12/16 02:14:19 bde Exp $ */ #include <sys/param.h> @@ -513,7 +513,25 @@ tcp_mtudisc(inp, errno) taop = rmx_taop(rt->rt_rmx); offered = taop->tao_mssopt; mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); - mss = min(mss, offered); + if (offered) + mss = min(mss, offered); + /* + * XXX - The above conditional probably violates the TCP + * spec. The problem is that, since we don't know the + * other end's MSS, we are supposed to use a conservative + * default. But, if we do that, then MTU discovery will + * never actually take place, because the conservative + * default is much less than the MTUs typically seen + * on the Internet today. For the moment, we'll sweep + * this under the carpet. + * + * The conservative default might not actually be a problem + * if the only case this occurs is when sending an initial + * SYN with options and data to a host we've never talked + * to before. Then, they will reply with an MSS value which + * will get recorded and the new parameters should get + * recomputed. For Further Study. + */ if (tp->t_maxopd <= mss) return; tp->t_maxopd = mss; |
