Date: Fri, 8 Mar 1996 03:38:10 -0800 From: Matthew Dillon <dillon@backplane.com> To: bugs@freebsd.org Subject: bug in netinet/tcp_input.c Message-ID: <199603081138.DAA00564@apollo.backplane.com>
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This is a non-fatal bug that nevertheless defeats all of the
recvpipe/sendpipe/mtu stuff in the routing tables.
Specifically, the tcp_mssopt() procedure fails to use the
rt->rt_rmx.rmx_mtu information when calculating the maximum
segment size for outgoing connections. This results in the
remote end sending us packets larger then we intend, messing
up any fine tuning we tried to do with the route recvpipe/sendpipe/mtu.
In anycase, the fix is simple. Here's a new tcp_mssopt() routine:
int
tcp_mssopt(tp)
struct tcpcb *tp;
{
struct rtentry *rt;
int mss;
rt = tcp_rtlookup(tp->t_inpcb);
if (rt == NULL)
return tcp_mssdflt;
mss = rt->rt_ifp->if_mtu;
if (rt->rt_rmx.rmx_mtu)
mss = min(mss, rt->rt_rmx.rmx_mtu);
mss -= sizeof(struct tcpiphdr);
if (mss < 20)
mss = 20;
return(mss);
}
Enjoy!
-Matt
Matthew Dillon Engineering, BEST Internet Communications, Inc.
<dillon@apollo.backplane.com>
[always include a portion of the original email in any response!]
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