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Initial back-end support for IP MTU discovery, gated on MTUDISC. The support
for TCP has yet to be written.
This commit is contained in:
Garrett Wollman
parent
f24b54a614
commit
5cbf3e086c
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=10881
@ -26,7 +26,7 @@
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: in_rmx.c,v 1.14 1995/06/21 19:48:53 wollman Exp $
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* $Id: in_rmx.c,v 1.15 1995/07/10 15:39:10 wollman Exp $
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*/
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/*
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@ -64,7 +64,9 @@
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#ifndef MTUDISC
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#include <netinet/tcpip.h>
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#endif /* not MTUDISC */
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#define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */
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@ -104,16 +106,22 @@ in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
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if (!rt->rt_rmx.rmx_recvpipe && !(rt->rt_rmx.rmx_locks & RTV_RPIPE))
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rt->rt_rmx.rmx_recvpipe = tcp_recvspace;
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#ifndef MTUDISC
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/*
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* Finally, set an MTU, again duplicating logic in TCP.
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* The in_localaddr() business will go away when we have
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* proper PMTU discovery.
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*/
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#endif /* not MTUDISC */
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if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU)
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&& rt->rt_ifp)
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#ifndef MTUDISC
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rt->rt_rmx.rmx_mtu = (in_localaddr(sin->sin_addr)
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? rt->rt_ifp->if_mtu
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: tcp_mssdflt + sizeof(struct tcpiphdr));
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#else /* MTUDISC */
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rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
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#endif /* MTUDISC */
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return rn_addroute(v_arg, n_arg, head, treenodes);
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}
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@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
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* $Id: ip_icmp.c,v 1.8 1995/07/10 16:16:00 wollman Exp $
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* $Id: ip_icmp.c,v 1.9 1995/08/29 17:49:04 wollman Exp $
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*/
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#include <sys/param.h>
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@ -302,6 +302,46 @@ icmp_input(m, hlen)
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printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
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#endif
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icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
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#ifdef MTUDISC
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/*
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* MTU discovery:
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* If we got a needfrag and there is a host route to the
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* original destination, and the MTU is not locked, then
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* set the MTU in the route to the suggested new value
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* (if given) and then notify as usual. The ULPs will
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* notice that the MTU has changed and adapt accordingly.
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* If no new MTU was suggested, then we guess a new one
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* less than the current value. If the new MTU is
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* unreasonably small (arbitrarily set at 296), then
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* we reset the MTU to the interface value and enable the
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* lock bit, indicating that we are no longer doing MTU
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* discovery.
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*/
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if (code == PRC_MSGSIZE) {
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struct rtentry *rt;
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int mtu;
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rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
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RTF_CLONING | RTF_PRCLONING);
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if (rt && (rt->rt_flags & RTF_HOST)
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&& !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
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mtu = ntohs(icp->icmp_nextmtu);
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if (!mtu)
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mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
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1);
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if (!mtu || mtu < 296) {
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rt->rt_rmx.rmx_mtu =
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rt->rt_ifp->if_mtu;
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rt->rt_rmx.rmx_locks |= RTV_MTU;
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} else if (rt->rt_rmx.rmx_mtu > mtu) {
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rt->rt_rmx.rmx_mtu = mtu;
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}
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}
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if (rt)
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RTFREE(rt);
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}
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#endif /* MTUDISC */
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ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
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if (ctlfunc)
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(*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
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@ -612,3 +652,43 @@ icmp_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
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}
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/* NOTREACHED */
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}
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#ifdef MTUDISC
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/*
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* Return the next larger or smaller MTU plateau (table from RFC 1191)
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* given current value MTU. If DIR is less than zero, a larger plateau
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* is returned; otherwise, a smaller value is returned.
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*/
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int
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ip_next_mtu(mtu, dir)
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int mtu;
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int dir;
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{
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static int mtutab[] = {
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65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
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68, 0
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};
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int i;
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for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
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if (mtu >= mtutab[i])
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break;
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}
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if (dir < 0) {
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if (i == 0) {
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return 0;
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} else {
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return mtutab[i - 1];
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}
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} else {
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if (mtutab[i] == 0) {
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return 0;
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} else if(mtu > mtutab[i]) {
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return mtutab[i];
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} else {
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return mtutab[i + 1];
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}
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}
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}
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#endif /* MTUDISC */
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@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)ip_var.h 8.1 (Berkeley) 6/10/93
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* $Id: ip_var.h,v 1.12 1995/06/28 05:13:02 davidg Exp $
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* $Id: ip_var.h,v 1.13 1995/07/26 18:05:16 wollman Exp $
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*/
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#ifndef _NETINET_IP_VAR_H_
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@ -175,6 +175,9 @@ int ip_getmoptions __P((int, struct ip_moptions *, struct mbuf **));
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void ip_init __P((void));
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extern int (*ip_mforward) __P((struct ip *, struct ifnet *, struct mbuf *,
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struct ip_moptions *));
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#ifdef MTUDISC
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int ip_next_mtu __P((int, int));
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#endif /* MTUDISC */
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int ip_optcopy __P((struct ip *, struct ip *));
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int ip_output __P((struct mbuf *,
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struct mbuf *, struct route *, int, struct ip_moptions *));
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@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93
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* $Id: tcp_subr.c,v 1.12 1995/06/19 16:45:33 wollman Exp $
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* $Id: tcp_subr.c,v 1.13 1995/06/29 18:11:23 wollman Exp $
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*/
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#include <sys/param.h>
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@ -429,6 +429,10 @@ tcp_notify(inp, error)
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sowwakeup(so);
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}
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#ifdef MTUDISC
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static void tcp_mtudisc __P((struct inpcb *, int));
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#endif /* MTUDISC */
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void
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tcp_ctlinput(cmd, sa, ip)
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int cmd;
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@ -440,6 +444,10 @@ tcp_ctlinput(cmd, sa, ip)
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if (cmd == PRC_QUENCH)
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notify = tcp_quench;
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#ifdef MTUDISC
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else if (cmd == PRC_MSGSIZE)
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notify = tcp_mtudisc;
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#endif /* MTUDISC */
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else if (!PRC_IS_REDIRECT(cmd) &&
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((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0))
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return;
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@ -466,6 +474,26 @@ tcp_quench(inp, errno)
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tp->snd_cwnd = tp->t_maxseg;
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}
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#ifdef MTUDISC
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/*
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* When `need fragmentation' ICMP is received, update our idea of the MSS
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* based on the new value in the route. Also nudge TCP to send something,
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* since we know the packet we just sent was dropped.
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*/
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static void
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tcp_mtudisc(inp, errno)
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struct inpcb *inp;
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int errno;
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{
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struct tcpcb *tp = intotcpcb(inp);
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#if 0
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if (tp)
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; /* XXX implement */
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#endif
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}
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#endif /* MTUDISC */
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/*
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* Look-up the routing entry to the peer of this inpcb. If no route
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* is found and it cannot be allocated the return NULL. This routine
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@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93
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* $Id: tcp_subr.c,v 1.12 1995/06/19 16:45:33 wollman Exp $
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* $Id: tcp_subr.c,v 1.13 1995/06/29 18:11:23 wollman Exp $
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*/
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#include <sys/param.h>
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@ -429,6 +429,10 @@ tcp_notify(inp, error)
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sowwakeup(so);
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}
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#ifdef MTUDISC
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static void tcp_mtudisc __P((struct inpcb *, int));
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#endif /* MTUDISC */
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void
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tcp_ctlinput(cmd, sa, ip)
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int cmd;
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@ -440,6 +444,10 @@ tcp_ctlinput(cmd, sa, ip)
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if (cmd == PRC_QUENCH)
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notify = tcp_quench;
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#ifdef MTUDISC
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else if (cmd == PRC_MSGSIZE)
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notify = tcp_mtudisc;
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#endif /* MTUDISC */
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else if (!PRC_IS_REDIRECT(cmd) &&
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((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0))
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return;
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@ -466,6 +474,26 @@ tcp_quench(inp, errno)
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tp->snd_cwnd = tp->t_maxseg;
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}
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#ifdef MTUDISC
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/*
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* When `need fragmentation' ICMP is received, update our idea of the MSS
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* based on the new value in the route. Also nudge TCP to send something,
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* since we know the packet we just sent was dropped.
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*/
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static void
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tcp_mtudisc(inp, errno)
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struct inpcb *inp;
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int errno;
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{
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struct tcpcb *tp = intotcpcb(inp);
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#if 0
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if (tp)
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; /* XXX implement */
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#endif
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}
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#endif /* MTUDISC */
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/*
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* Look-up the routing entry to the peer of this inpcb. If no route
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* is found and it cannot be allocated the return NULL. This routine
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