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If we don't get a suggested MTU during path MTU discovery

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look up the packet size of the packet that generated the
response, step down the MTU by one step through ip_next_mtu()
and try again.

Suggested by:	dwmalone
This commit is contained in:
andre 2005-05-04 13:48:44 +00:00
parent a0f1ce3be1
commit 757e9ec267
2 changed files with 40 additions and 18 deletions
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29
sys/netinet/tcp_subr.c
View File

@ -1168,22 +1168,33 @@ tcp_ctlinput(cmd, sa, vip)
* If we got a needfrag set the MTU
* in the route to the suggested new
* value (if given) and then notify.
* If no new MTU was suggested, then
* we guess a new one less than the
* current value.
* If the new MTU is unreasonably
* small (defined by sysctl tcp_minmss),
* then we up the MTU value to minimum.
*/
bzero(&inc, sizeof(inc));
inc.inc_flags = 0; /* IPv4 */
inc.inc_faddr = faddr;
mtu = ntohs(icp->icmp_nextmtu);
/*
* If no alternative MTU was
* proposed, try the next smaller
* one.
*/
if (!mtu)
mtu = ip_next_mtu(mtu, 1);
if (mtu >= max(296, (tcp_minmss
+ sizeof(struct tcpiphdr))))
mtu = ip_next_mtu(ntohs(ip->ip_len),
1);
if (mtu < max(296, (tcp_minmss)
+ sizeof(struct tcpiphdr)))
mtu = 0;
if (!mtu)
mtu = tcp_mssdflt
+ sizeof(struct tcpiphdr);
/*
* Only cache the the MTU if it
* is smaller than the interface
* or route MTU. tcp_mtudisc()
* will do right thing by itself.
*/
if (mtu <= tcp_maxmtu(&inc))
tcp_hc_updatemtu(&inc, mtu);
}

29
sys/netinet/tcp_timewait.c
View File

@ -1168,22 +1168,33 @@ tcp_ctlinput(cmd, sa, vip)
* If we got a needfrag set the MTU
* in the route to the suggested new
* value (if given) and then notify.
* If no new MTU was suggested, then
* we guess a new one less than the
* current value.
* If the new MTU is unreasonably
* small (defined by sysctl tcp_minmss),
* then we up the MTU value to minimum.
*/
bzero(&inc, sizeof(inc));
inc.inc_flags = 0; /* IPv4 */
inc.inc_faddr = faddr;
mtu = ntohs(icp->icmp_nextmtu);
/*
* If no alternative MTU was
* proposed, try the next smaller
* one.
*/
if (!mtu)
mtu = ip_next_mtu(mtu, 1);
if (mtu >= max(296, (tcp_minmss
+ sizeof(struct tcpiphdr))))
mtu = ip_next_mtu(ntohs(ip->ip_len),
1);
if (mtu < max(296, (tcp_minmss)
+ sizeof(struct tcpiphdr)))
mtu = 0;
if (!mtu)
mtu = tcp_mssdflt
+ sizeof(struct tcpiphdr);
/*
* Only cache the the MTU if it
* is smaller than the interface
* or route MTU. tcp_mtudisc()
* will do right thing by itself.
*/
if (mtu <= tcp_maxmtu(&inc))
tcp_hc_updatemtu(&inc, mtu);
}