usr/src/sbin/XNSrouted/input.c

/*
 * Copyright (c) 1985 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 * Includes material written at Cornell University by Bill Nesheim,
 * by permission of the author.
 */


#ifndef lint
static char sccsid[] = "@(#)input.c     5.5 (Berkeley) %G%";
#endif not lint

/*
 * XNS Routing Table Management Daemon
 */
#include "defs.h"

struct sockaddr *
xns_nettosa(net)
u_short *net;
{
        static struct sockaddr_ns sxn;
        extern char ether_broadcast_addr[6];

        bzero(&sxn, sizeof (struct sockaddr_ns));
        sxn.sns_family = AF_NS;
        xnnet(sxn.sns_addr.x_net) = xnnet(net[0]);
        sxn.sns_addr.x_host = *(union ns_host *)ether_broadcast_addr;
        return( (struct sockaddr *)&sxn);

}

/*
 * Process a newly received packet.
 */
rip_input(from, size)
        struct sockaddr *from;
        int size;
{
        struct rt_entry *rt;
        struct netinfo *n;
        struct interface *ifp;
        int newsize;
        struct afswitch *afp;


        ifp = 0;
        TRACE_INPUT(ifp, from, size);
        if (from->sa_family >= AF_MAX)
                return;
        afp = &afswitch[from->sa_family];

        size -= sizeof (u_short)        /* command */;
        n = msg->rip_nets;

        switch (ntohs(msg->rip_cmd)) {

        case RIPCMD_REQUEST:
                newsize = 0;
                while (size > 0) {
                        if (size < sizeof (struct netinfo))
                                break;
                        size -= sizeof (struct netinfo);

                        /*
                         * A single entry with rip_dst == DSTNETS_ALL and
                         * metric ``infinity'' means ``all routes''.
                         */
                        if (ntohl(xnnet(n->rip_dst[0])) == DSTNETS_ALL &&
                            ntohs(n->rip_metric) == HOPCNT_INFINITY &&
                            size == 0) {
                                ifp = if_ifwithnet(from);
                                supply(from, 0, ifp);
                                return;
                        }
                        /*
                         * request for specific nets
                         */
                        rt = rtlookup(xns_nettosa(n->rip_dst));
                        if (ftrace) {
                                fprintf(ftrace,
                                        "specific request for %d",
                                        ntohl(xnnet(n->rip_dst[0])));
                                fprintf(ftrace,
                                        "yields route %x",
                                        rt);
                        }
                        n->rip_metric = htons( rt == 0 ? HOPCNT_INFINITY :
                                min(rt->rt_metric+1, HOPCNT_INFINITY));
                        n++, newsize += sizeof (struct netinfo);
                }
                if (newsize > 0) {
                        msg->rip_cmd = htons(RIPCMD_RESPONSE);
                        newsize += sizeof (u_short);
                        /* should check for if with dstaddr(from) first */
                        (*afp->af_output)(0, from, newsize);
                        (ifp = if_ifwithnet(from));
                        if (ftrace) {
                                fprintf(ftrace,
                                        ", request arriving on interface %x\n",
                                        ifp);
                        }
                }
                return;

        case RIPCMD_RESPONSE:
                /* verify message came from a router */
                if ((*afp->af_portmatch)(from) == 0)
                        return;
                (*afp->af_canon)(from);
                /* are we talking to ourselves? */
                if (ifp = if_ifwithaddr(from)) {
                        rt = rtfind(from);
                        if (rt == 0 || (rt->rt_state & RTS_INTERFACE) == 0)
                                addrouteforif(ifp);
                        else
                                rt->rt_timer = 0;
                        return;
                }
                /* Update timer for interface on which the packet arrived.
                 * If from other end of a point-to-point link that isn't
                 * in the routing tables, (re-)add the route.
                 */
                if ((rt = rtfind(from)) && (rt->rt_state & RTS_INTERFACE)) {
                        if(ftrace) fprintf(ftrace, "Got route\n");
                        rt->rt_timer = 0;
                } else if (ifp = if_ifwithdstaddr(from)) {
                        if(ftrace) fprintf(ftrace, "Got partner\n");
                        addrouteforif(ifp);
                }
                for (; size > 0; size -= sizeof (struct netinfo), n++) {
                        struct sockaddr *sa;
                        if (size < sizeof (struct netinfo))
                                break;
                        if ((unsigned) ntohs(n->rip_metric) >= HOPCNT_INFINITY)
                                continue;
                        rt = rtfind(sa = xns_nettosa(n->rip_dst));
                        if (rt == 0) {
                                rtadd(sa, from, ntohs(n->rip_metric), 0);
                                continue;
                        }

                        /*
                         * Update if from gateway and different,
                         * from anywhere and shorter, or getting stale and equivalent.
                         */
                        if ((equal(from, &rt->rt_router) &&
                            ntohs(n->rip_metric) != rt->rt_metric ) ||
                            (unsigned) ntohs(n->rip_metric) < rt->rt_metric ||
                            (rt->rt_timer > (EXPIRE_TIME/2) &&
                            rt->rt_metric == ntohs(n->rip_metric))) {
                                rtchange(rt, from, ntohs(n->rip_metric));
                                rt->rt_timer = 0;
                        }
                }
                return;
        }
}