xref: /netbsd-src/usr.sbin/mrouted/route.c (revision ce0bb6e8d2e560ecacbe865a848624f94498063b)

/*
 * The mrouted program is covered by the license in the accompanying file
 * named "LICENSE".  Use of the mrouted program represents acceptance of
 * the terms and conditions listed in that file.
 *
 * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
 * Leland Stanford Junior University.
 *
 *
 * from: Id: route.c,v 1.5 1993/06/24 05:11:16 deering Exp
 *      $Id: route.c,v 1.2 1994/05/08 15:08:56 brezak Exp $
 */

#ifndef lint
static char rcsid[] = "$Id: route.c,v 1.2 1994/05/08 15:08:56 brezak Exp $";
#endif

#include "defs.h"


/*
 * Exported variables.
 */
int routes_changed;			/* 1=>some routes have changed */
int delay_change_reports;		/* 1=>postpone change reports  */


/*
 * Private variables.
 */
static struct rtentry *routing_table;	/* pointer to list of route entries */
static struct rtentry *rtp;		/* pointer to a route entry         */
unsigned nroutes;			/* current number of route entries  */


/*
 * Initialize the routing table and associated variables.
 */
void init_routes()
{
    routing_table        = NULL;
    nroutes		 = 0;
    routes_changed       = FALSE;
    delay_change_reports = FALSE;
}


/*
 * Initialize the children and leaf bits for route 'r', along with the
 * associated dominant, subordinate, and leaf timing data structures.
 * Return TRUE if this changes the value of either the children or
 * leaf bitmaps for 'r'.
 */
static int init_children_and_leaves(r, parent)
    register struct rtentry *r;
    register vifi_t parent;
{
    register vifi_t vifi;
    register struct uvif *v;
    vifbitmap_t old_children, old_leaves;

    VIFM_COPY(r->rt_children, old_children);
    VIFM_COPY(r->rt_leaves,   old_leaves  );

    VIFM_CLRALL(r->rt_children);
    VIFM_CLRALL(r->rt_leaves);
    r->rt_flags &= ~RTF_LEAF_TIMING;

    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
	r->rt_dominants   [vifi] = 0;
	r->rt_subordinates[vifi] = 0;

	if (vifi != parent && !(v->uv_flags & (VIFF_DOWN|VIFF_DISABLED))) {
	    VIFM_SET(vifi, r->rt_children);
	    if (v->uv_neighbors == NULL) {
		VIFM_SET(vifi, r->rt_leaves);
		r->rt_leaf_timers[vifi] = 0;
	    }
	    else {
		r->rt_leaf_timers[vifi] = LEAF_CONFIRMATION_TIME;
		r->rt_flags |= RTF_LEAF_TIMING;
	    }
	}
	else {
	    r->rt_leaf_timers[vifi] = 0;
	}
    }

    return (!VIFM_SAME(r->rt_children, old_children) ||
	    !VIFM_SAME(r->rt_leaves,   old_leaves));
}


/*
 * A new vif has come up -- update the children and leaf bitmaps in all route
 * entries to take that into account.
 */
void add_vif_to_routes(vifi)
    register vifi_t vifi;
{
    register struct rtentry *r;
    register struct uvif *v;

    v = &uvifs[vifi];
    for (r = routing_table; r != NULL; r = r->rt_next) {
	if (r->rt_metric != UNREACHABLE &&
	    !VIFM_ISSET(vifi, r->rt_children)) {
	    VIFM_SET(vifi, r->rt_children);
	    r->rt_dominants   [vifi] = 0;
	    r->rt_subordinates[vifi] = 0;
	    if (v->uv_neighbors == NULL) {
		VIFM_SET(vifi, r->rt_leaves);
		r->rt_leaf_timers[vifi] = 0;
	    }
	    else {
		VIFM_CLR(vifi, r->rt_leaves);
		r->rt_leaf_timers[vifi] = LEAF_CONFIRMATION_TIME;
		r->rt_flags |= RTF_LEAF_TIMING;
	    }
	    k_update_route(r);
	}
    }
}


/*
 * A vif has gone down -- expire all routes that have that vif as parent,
 * and update the children bitmaps in all other route entries to take into
 * account the failed vif.
 */
void delete_vif_from_routes(vifi)
    register vifi_t vifi;
{
    register struct rtentry *r;

    for (r = routing_table; r != NULL; r = r->rt_next) {
	if (r->rt_metric != UNREACHABLE) {
	    if (vifi == r->rt_parent) {
		k_del_route(r);
		r->rt_timer    = ROUTE_EXPIRE_TIME;
		r->rt_metric   = UNREACHABLE;
		r->rt_flags   |= RTF_CHANGED;
		routes_changed = TRUE;
	    }
	    else if (VIFM_ISSET(vifi, r->rt_children)) {
		VIFM_CLR(vifi, r->rt_children);
		VIFM_CLR(vifi, r->rt_leaves);
		r->rt_subordinates[vifi] = 0;
		r->rt_leaf_timers [vifi] = 0;
		k_update_route(r);
	    }
	    else {
		r->rt_dominants[vifi] = 0;
	    }
	}
    }
}


/*
 * A neighbor has failed or become unreachable.  If that neighbor was
 * considered a dominant or subordinate router in any route entries,
 * take appropriate action.
 */
void delete_neighbor_from_routes(addr, vifi)
    register u_long addr;
    register vifi_t vifi;
{
    register struct rtentry *r;
    register struct uvif *v;

    v = &uvifs[vifi];
    for (r = routing_table; r != NULL; r = r->rt_next) {
	if (r->rt_metric != UNREACHABLE) {
	    if (r->rt_dominants[vifi] == addr) {
		VIFM_SET(vifi, r->rt_children);
		r->rt_dominants   [vifi] = 0;
		r->rt_subordinates[vifi] = 0;
		if (v->uv_neighbors == NULL) {
		    VIFM_SET(vifi, r->rt_leaves);
		    r->rt_leaf_timers[vifi] = 0;
		}
		else {
		    VIFM_CLR(vifi, r->rt_leaves);
		    r->rt_leaf_timers[vifi] = LEAF_CONFIRMATION_TIME;
		    r->rt_flags |= RTF_LEAF_TIMING;
		}
		k_update_route(r);
	    }
	    else if (r->rt_subordinates[vifi] == addr) {
		r->rt_subordinates[vifi] = 0;
		if (v->uv_neighbors == NULL) {
		    VIFM_SET(vifi, r->rt_leaves);
		    k_update_route(r);
		}
		else {
		    r->rt_leaf_timers[vifi] = LEAF_CONFIRMATION_TIME;
		    r->rt_flags |= RTF_LEAF_TIMING;
		}
	    }
	    else if (v->uv_neighbors == NULL &&
		     r->rt_leaf_timers[vifi] != 0) {
		VIFM_SET(vifi, r->rt_leaves);
		r->rt_leaf_timers[vifi] = 0;
		k_update_route(r);
	    }
	}
    }
}


/*
 * Prepare for a sequence of ordered route updates by initializing a pointer
 * to the start of the routing table.  The pointer is used to remember our
 * position in the routing table in order to avoid searching from the
 * beginning for each update; this relies on having the route reports in
 * a single message be in the same order as the route entries in the routing
 * table.
 */
void start_route_updates()
{
    rtp = (struct rtentry *)&routing_table;
}


/*
 * Starting at the route entry following the one to which 'rtp' points,
 * look for a route entry matching the specified origin and mask.  If a
 * match is found, return TRUE and leave 'rtp' pointing at the found entry.
 * If no match is found, return FALSE and leave 'rtp' pointing to the route
 * entry preceding the point at which the new origin should be inserted.
 * This code is optimized for the normal case in which the first entry to
 * be examined is the matching entry.
 */
static int find_route(origin, mask)
    register u_long origin, mask;
{
    register struct rtentry *r;

    r = rtp->rt_next;
    while (r != NULL) {
	if (origin == r->rt_origin && mask == r->rt_originmask) {
	    rtp = r;
	    return (TRUE);
	}
	if (ntohl(mask) > ntohl(r->rt_originmask) ||
	    (mask == r->rt_originmask &&
	     ntohl(origin) > ntohl(r->rt_origin))) {
	    rtp = r;
	    r = r->rt_next;
	}
	else break;
    }
    return (FALSE);
}


/*
 * Search the entire routing table, looking for an entry which conflicts
 * with the given origin and mask, for example, an entry which has the same
 * origin under a different mask.  If a conflicting entry is found, return
 * a pointer to the entry preceding it (to facilitate deletion); if no
 * conflict is found, return NULL.
 */
static struct rtentry *find_conflicting_route(origin, mask)
    register u_long origin, mask;
{
    register struct rtentry *r, *prev_r;

    for (prev_r = (struct rtentry *)&routing_table, r = routing_table;
	 r != NULL;
	 prev_r = r, r = r->rt_next ) {
	if ((origin & r->rt_originmask) == r->rt_origin ||
	    (r->rt_origin & mask) == origin) {
	    return (prev_r);
	}
    }
    return (NULL);
}


/*
 * Create a new routing table entry for the specified origin and link it into
 * the routing table.  The shared variable 'rtp' is assumed to point to the
 * routing entry after which the new one should be inserted.  It is left
 * pointing to the new entry.
 *
 * Only the origin, originmask, originwidth and flags fields are initialized
 * in the new route entry; the caller is responsible for filling in the the
 * rest.
 */
static void create_route(origin, mask)
    u_long origin, mask;
{
    register struct rtentry *r;

    if ((r = (struct rtentry *) malloc(sizeof(struct rtentry)
				+ (3 * numvifs * sizeof(u_long)))) == NULL) {
	log(LOG_ERR, 0, "ran out of memory");	/* fatal */
    }
    r->rt_origin     = origin;
    r->rt_originmask = mask;
    if      (((char *)&mask)[3] != 0) r->rt_originwidth = 4;
    else if (((char *)&mask)[2] != 0) r->rt_originwidth = 3;
    else if (((char *)&mask)[1] != 0) r->rt_originwidth = 2;
    else                              r->rt_originwidth = 1;
    r->rt_flags        = 0;
    r->rt_dominants    = (u_long *)(r + 1);
    r->rt_subordinates = (u_long *)(r->rt_dominants + numvifs);
    r->rt_leaf_timers  = (u_long *)(r->rt_subordinates + numvifs);

    r->rt_next = rtp->rt_next;
    rtp->rt_next = r;
    rtp = r;
    ++nroutes;
}


/*
 * Discard the routing table entry following the one to which 'prev_r' points.
 */
static void discard_route(prev_r)
    register struct rtentry *prev_r;
{
    register struct rtentry *r;

    r = prev_r->rt_next;
    prev_r->rt_next = r->rt_next;
    free((char *)r);
    --nroutes;
}


/*
 * Process a route report for a single origin, creating or updating the
 * corresponding routing table entry if necessary.  'src' is either the
 * address of a neighboring router from which the report arrived, or zero
 * to indicate a change of status of one of our own interfaces.
 */
void update_route(origin, mask, metric, src, vifi)
    u_long origin, mask;
    int metric;
    u_long src;
    vifi_t vifi;
{
    register struct rtentry *r;
    struct rtentry *prev_r;
    int adj_metric;

    /*
     * Compute an adjusted metric, taking into account the cost of the
     * subnet or tunnel over which the report arrived, and normalizing
     * all unreachable/poisoned metrics into a single value.
     */
    if (src != 0 && (metric < 1 || metric >= 2*UNREACHABLE)) {
	log(LOG_WARNING, 0,
	    "%s reports out-of-range metric %u for origin %s",
	    inet_fmt(src, s1), metric, inet_fmts(origin, mask, s2));
	return;
    }
    adj_metric = metric + uvifs[vifi].uv_metric;
    if (adj_metric > UNREACHABLE) adj_metric = UNREACHABLE;

    /*
     * Look up the reported origin in the routing table.
     */
    if (!find_route(origin, mask)) {
	/*
	 * Not found.
	 * Don't create a new entry if the report says it's unreachable,
	 * or if the reported origin and mask are invalid.
	 */
	if (adj_metric == UNREACHABLE) {
	    return;
	}
	if (src != 0 && !inet_valid_subnet(origin, mask)) {
	    log(LOG_WARNING, 0,
		"%s reports an invalid origin (%s) and/or mask (%08x)",
		inet_fmt(src, s1), inet_fmt(origin, s2), ntohl(mask));
	    return;
	}

	/*
	 * If the new origin and mask are inconsistent with an entry
	 * already in the routing table, either ignore this update
	 * (if it came from another router), or delete the conflicting
	 * entry (if the update is for a directly-connected subnet).
	 */
	if ((prev_r = find_conflicting_route(origin, mask)) != NULL ) {
	    if (src != 0) {
		log(LOG_INFO, 0,
		    "%s reports a conflicting origin (%s) and mask (%08x)",
		    inet_fmt(src, s1), inet_fmt(origin, s2), ntohl(mask));
		return;
	    }
	    else {
		r = prev_r->rt_next;
		log(LOG_INFO, 0,
		   "deleting route with conflicting origin (%s), mask (%08x)",
		   inet_fmt(r->rt_origin, s1), ntohl(r->rt_originmask));

		if (r->rt_metric != UNREACHABLE) {
		    k_del_route(r);
		}
		discard_route(prev_r);
		if (rtp == r) rtp = prev_r;
	    }
	}

	/*
	 * OK, create the new routing entry.  'rtp' will be left pointing
	 * to the new entry.
	 */
	create_route(origin, mask);

	rtp->rt_metric = UNREACHABLE;	/* temporary; updated below */
    }

    /*
     * We now have a routing entry for the reported origin.  Update it?
     */
    r = rtp;
    if (r->rt_metric == UNREACHABLE) {
	/*
	 * The routing entry is for a formerly-unreachable or new origin.
	 * If the report claims reachability, update the entry to use
	 * the reported route.
	 */
	if (adj_metric == UNREACHABLE)
	    return;

	r->rt_parent   = vifi;
	init_children_and_leaves(r, vifi);
	k_add_route(r);
	r->rt_gateway  = src;
	r->rt_timer    = 0;
	r->rt_metric   = adj_metric;
	r->rt_flags   |= RTF_CHANGED;
	routes_changed = TRUE;
    }
    else if (src == r->rt_gateway) {
	/*
	 * The report has come either from the interface directly-connected
	 * to the origin subnet (src and r->rt_gateway both equal zero) or
	 * from the gateway we have chosen as the best first-hop gateway back
	 * towards the origin (src and r->rt_gateway not equal zero).  Reset
	 * the route timer and, if the reported metric has changed, update
	 * our entry accordingly.
	 */
	r->rt_timer = 0;
	if (adj_metric == r->rt_metric)
	    return;

	if (adj_metric == UNREACHABLE) {
	    k_del_route(r);
	    r->rt_timer = ROUTE_EXPIRE_TIME;
	}
	else if (adj_metric < r->rt_metric) {
	    if (init_children_and_leaves(r, vifi)) {
		k_update_route(r);
	    }
	}
	r->rt_metric   = adj_metric;
	r->rt_flags   |= RTF_CHANGED;
	routes_changed = TRUE;
    }
    else if (src == 0 ||
		(r->rt_gateway != 0 &&
		    (adj_metric < r->rt_metric ||
			(adj_metric == r->rt_metric &&
			    r->rt_timer >= ROUTE_SWITCH_TIME)))) {
	/*
	 * The report is for an origin we consider reachable; the report
	 * comes either from one of our own interfaces or from a gateway
	 * other than the one we have chosen as the best first-hop gateway
	 * back towards the origin.  If the source of the update is one of
	 * our own interfaces, or if the origin is not a directly-connected
	 * subnet and the reported metric for that origin is better than
	 * what our routing entry says, update the entry to use the new
	 * gateway and metric.  We also switch gateways if the reported
	 * metric is the same as the one in the route entry and the gateway
	 * associated with the route entry has not been heard from recently.
	 * Did you get all that?
	 */
	if (r->rt_parent != vifi || adj_metric < r->rt_metric) {
	    r->rt_parent = vifi;
	    if (init_children_and_leaves(r, vifi)) {
		k_update_route(r);
	    }
	}
	r->rt_gateway  = src;
	r->rt_timer    = 0;
	r->rt_metric   = adj_metric;
	r->rt_flags   |= RTF_CHANGED;
	routes_changed = TRUE;
    }
    else if (vifi != r->rt_parent) {
	/*
	 * The report came from a vif other than the route's parent vif.
	 * Update the children and leaf info, if necessary.
	 */
	if (VIFM_ISSET(vifi, r->rt_children)) {
	    /*
	     * Vif is a child vif for this route.
	     */
	    if (metric  < r->rt_metric ||
	       (metric == r->rt_metric &&
			ntohl(src) < ntohl(uvifs[vifi].uv_lcl_addr))) {
		/*
		 * Neighbor has lower metric to origin (or has same metric
		 * and lower IP address) -- it becomes the dominant router,
		 * and vif is no longer a child for me.
		 */
		VIFM_CLR(vifi, r->rt_children);
		VIFM_CLR(vifi, r->rt_leaves);
		r->rt_dominants   [vifi] = src;
		r->rt_subordinates[vifi] = 0;
		r->rt_leaf_timers [vifi] = 0;
		k_update_route(r);
	    }
	    else if (metric > UNREACHABLE) {	/* "poisoned reverse" */
		/*
		 * Neighbor considers this vif to be on path to route's
		 * origin; if no subordinate recorded, record this neighbor
		 * as subordinate and clear the leaf flag.
		 */
		if (r->rt_subordinates[vifi] == 0) {
		    VIFM_CLR(vifi, r->rt_leaves);
		    r->rt_subordinates[vifi] = src;
		    r->rt_leaf_timers [vifi] = 0;
		    k_update_route(r);
		}
	    }
	    else if (src == r->rt_subordinates[vifi]) {
		/*
		 * Current subordinate no longer considers this vif to be on
		 * path to route's origin; it is no longer a subordinate
		 * router, and we set the leaf confirmation timer to give
		 * us time to hear from other subordinates.
		 */
		r->rt_subordinates[vifi] = 0;
		if (uvifs[vifi].uv_neighbors == NULL ||
		    uvifs[vifi].uv_neighbors->al_next == NULL) {
		    VIFM_SET(vifi, r->rt_leaves);
		    k_update_route(r);
		}
		else {
		    r->rt_leaf_timers [vifi] = LEAF_CONFIRMATION_TIME;
		    r->rt_flags |= RTF_LEAF_TIMING;
		}
	    }

	}
	else if (src == r->rt_dominants[vifi] &&
		(metric  > r->rt_metric ||
		(metric == r->rt_metric &&
			ntohl(src) > ntohl(uvifs[vifi].uv_lcl_addr)))) {
	    /*
	     * Current dominant no longer has a lower metric to origin
	     * (or same metric and lower IP address); we adopt the vif
	     * as our own child.
	     */
	    VIFM_SET(vifi, r->rt_children);
	    r->rt_dominants  [vifi] = 0;
	    if (metric > UNREACHABLE) {
		r->rt_subordinates[vifi] = src;
	    }
	    else if (uvifs[vifi].uv_neighbors == NULL ||
		     uvifs[vifi].uv_neighbors->al_next == NULL) {
		VIFM_SET(vifi, r->rt_leaves);
	    }
	    else {
		r->rt_leaf_timers[vifi] = LEAF_CONFIRMATION_TIME;
		r->rt_flags |= RTF_LEAF_TIMING;
	    }
	    k_update_route(r);
	}
    }
}


/*
 * On every timer interrupt, advance the timer in each routing entry.
 */
void age_routes()
{
    register struct rtentry *r;
    register struct rtentry *prev_r;
    register vifi_t vifi;

    for (prev_r = (struct rtentry *)&routing_table, r = routing_table;
	 r != NULL;
	 prev_r = r, r = r->rt_next) {

	if ((r->rt_timer += TIMER_INTERVAL) < ROUTE_EXPIRE_TIME) {
	    /*
	     * Route is still good; see if any leaf timers need to be
	     * advanced.
	     */
	    if (r->rt_flags & RTF_LEAF_TIMING) {
		r->rt_flags &= ~RTF_LEAF_TIMING;
		for (vifi = 0; vifi < numvifs; ++vifi) {
		    if (r->rt_leaf_timers[vifi] != 0) {
			/*
			 * Unlike other timers, leaf timers decrement.
			 */
			if ((r->rt_leaf_timers[vifi] -= TIMER_INTERVAL) == 0){
			    VIFM_SET(vifi, r->rt_leaves);
			    k_update_route(r);
			}
			else {
			    r->rt_flags |= RTF_LEAF_TIMING;
			}
		    }
		}
	    }
	}
	else if (r->rt_timer >= ROUTE_DISCARD_TIME) {
	    /*
	     * Time to garbage-collect the route entry.
	     */
	    discard_route(prev_r);
	    r = prev_r;
	}
	else if (r->rt_metric != UNREACHABLE) {
	    /*
	     * Time to expire the route entry.  If the gateway is zero,
	     * i.e., it is a route to a directly-connected subnet, just
	     * set the timer back to zero; such routes expire only when
	     * the interface to the subnet goes down.
	     */
	    if (r->rt_gateway == 0) {
		r->rt_timer = 0;
	     }
	    else {
		k_del_route(r);
		r->rt_metric   = UNREACHABLE;
		r->rt_flags   |= RTF_CHANGED;
		routes_changed = TRUE;
	    }
	}
    }
}


/*
 * Mark all routes as unreachable.  This function is called only from
 * hup() in preparation for informing all neighbors that we are going
 * off the air.  For consistency, we ought also to delete all reachable
 * route entries from the kernel, but since we are about to exit we rely
 * on the kernel to do its own cleanup -- no point in making all those
 * expensive kernel calls now.
 */
void expire_all_routes()
{
    register struct rtentry *r;

    for (r = routing_table; r != NULL; r = r->rt_next) {
	r->rt_metric   = UNREACHABLE;
	r->rt_flags   |= RTF_CHANGED;
	routes_changed = TRUE;
    }
}


/*
 * Process an incoming neighbor probe message.
 */
void accept_probe(src, dst)
    u_long src, dst;
{
    vifi_t vifi;

    if ((vifi = find_vif(src, dst)) == NO_VIF) {
	log(LOG_INFO, 0,
    	    "ignoring probe from non-neighbor %s", inet_fmt(src, s1));
	return;
    }

    if (!update_neighbor(vifi, src, DVMRP_PROBE))
	return;

    report(ALL_ROUTES, vifi, src);
}

struct newrt {
	u_long mask;
	u_long origin;
	int metric;
	int pad;
};

int compare_rts(r1, r2)
    register struct newrt *r1;
    register struct newrt *r2;
{
    register unsigned long m1 = ntohl(r1->mask);
    register unsigned long m2 = ntohl(r2->mask);
    register unsigned long o1, o2;

    if (m1 > m2)
	return (1);
    if (m1 < m2)
	return (-1);

    /* masks are equal */
    o1 = ntohl(r1->origin);
    o2 = ntohl(r2->origin);
    if (o1 > o2)
	return (1);
    if (o1 < o2)
	return (-1);
    return (0);
}

/*
 * Process an incoming route report message.
 */
void accept_report(src, dst, p, datalen)
    u_long src, dst;
    register char *p;
    register int datalen;
{
    vifi_t vifi;
    register int width, i, nrt = 0;
    int metric;
    u_long mask;
    u_long origin;
    struct newrt rt[4096];

    if ((vifi = find_vif(src, dst)) == NO_VIF) {
	log(LOG_INFO, 0,
    	    "ignoring route report from non-neighbor %s", inet_fmt(src, s1));
	return;
    }

    if (!update_neighbor(vifi, src, DVMRP_REPORT))
	return;

    if (datalen > 2*4096) {
	log(LOG_INFO, 0,
    	    "ignoring oversize (%d bytes) route report from %s",
	    datalen, inet_fmt(src, s1));
	return;
    }

    while (datalen > 0) {	/* Loop through per-mask lists. */
	if (datalen < 3) {
	    log(LOG_WARNING, 0,
		"received truncated route report from %s", inet_fmt(src, s1));
	    return;
	}
	((char *)&mask)[0] = 0xff;            width = 1;
	if ((((char *)&mask)[1] = *p++) != 0) width = 2;
	if ((((char *)&mask)[2] = *p++) != 0) width = 3;
	if ((((char *)&mask)[3] = *p++) != 0) width = 4;
	datalen -= 3;

	do {			/* Loop through (origin, metric) pairs */
	    if (datalen < width + 1) {
		log(LOG_WARNING, 0,
		"received truncated route report from %s", inet_fmt(src, s1));
		return;
	    }
	    origin = 0;
	    for (i = 0; i < width; ++i)
		((char *)&origin)[i] = *p++;
	    metric = *p++;
	    datalen -= width + 1;
	    rt[nrt].mask   = mask;
	    rt[nrt].origin = origin;
	    rt[nrt].metric = metric;
	    ++nrt;
	} while (!(metric & 0x80));
    }
    qsort((char*)rt, nrt, sizeof(rt[0]), compare_rts);
    start_route_updates();
    for (i = 0; i < nrt; ++i)
	update_route(rt[i].origin, rt[i].mask, (rt[i].metric & 0x7f), src, vifi);

    if (routes_changed && !delay_change_reports)
	report_to_all_neighbors(CHANGED_ROUTES);
}


/*
 * Send a route report message to destination 'dst', via virtual interface
 * 'vifi'.  'which_routes' specifies ALL_ROUTES or CHANGED_ROUTES.
 */
void report(which_routes, vifi, dst)
    int which_routes;
    vifi_t vifi;
    u_long dst;
{
    register struct rtentry *r;
    register char *p;
    register int i;
    int datalen;
    int width;
    u_long mask;
    u_long src;

    src = uvifs[vifi].uv_lcl_addr;

    p = send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN;
    datalen = 0;
    mask = 0;

    for (r = routing_table; r != NULL; r = r->rt_next) {

	if (which_routes == CHANGED_ROUTES && !(r->rt_flags & RTF_CHANGED))
	    continue;

	/*
	 * If there is no room for this route in the current message,
	 * send the message and start a new one.
	 */
	if (datalen + ((r->rt_originmask == mask) ?
			(width + 1) :
			(r->rt_originwidth + 4)) > MAX_DVMRP_DATA_LEN) {
	    *(p-1) |= 0x80;
	    send_igmp(src, dst, IGMP_DVMRP, DVMRP_REPORT,
			htonl(MROUTED_LEVEL), datalen);

	    p = send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN;
	    datalen = 0;
	    mask = 0;
	}

	if(r->rt_originmask != mask) {
	    mask  = r->rt_originmask;
	    width = r->rt_originwidth;
	    if (datalen != 0) *(p-1) |= 0x80;
	    *p++ = ((char *)&mask)[1];
	    *p++ = ((char *)&mask)[2];
	    *p++ = ((char *)&mask)[3];
	    datalen += 3;
	}

	for (i = 0; i < width; ++i)
	    *p++ = ((char *)&(r->rt_origin))[i];

	*p++ = (r->rt_parent == vifi && r->rt_metric != UNREACHABLE) ?
		(char)(r->rt_metric + UNREACHABLE) :  /* "poisoned reverse" */
		(char)(r->rt_metric);

	datalen += width + 1;
    }

    if (datalen != 0) {
	*(p-1) |= 0x80;
	send_igmp(src, dst, IGMP_DVMRP, DVMRP_REPORT,
			htonl(MROUTED_LEVEL), datalen);
    }
}


/*
 * Send a route report message to all neighboring routers.
 * 'which_routes' specifies ALL_ROUTES or CHANGED_ROUTES.
 */
void report_to_all_neighbors(which_routes)
    int which_routes;
{
    register vifi_t vifi;
    register struct uvif *v;
    register struct rtentry *r;
    int routes_changed_before;

    /*
     * Remember the state of the global routes_changed flag before
     * generating the reports, and clear the flag.
     */
    routes_changed_before = routes_changed;
    routes_changed = FALSE;


    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
	if (v->uv_neighbors != NULL) {
	    report(which_routes, vifi,
		   (v->uv_flags & VIFF_TUNNEL) ? v->uv_rmt_addr
					      : dvmrp_group);
	}
    }

    /*
     * If there were changed routes before we sent the reports AND
     * if no new changes occurred while sending the reports, clear
     * the change flags in the individual route entries.  If changes
     * did occur while sending the reports, new reports will be
     * generated at the next timer interrupt.
     */
    if (routes_changed_before && !routes_changed) {
	for (r = routing_table; r != NULL; r = r->rt_next) {
	    r->rt_flags &= ~RTF_CHANGED;
	}
    }

    /*
     * Set a flag to inhibit further reports of changed routes until the
     * next timer interrupt.  This is to alleviate update storms.
     */
    delay_change_reports = TRUE;
}

/*
 * Send a route report message to destination 'dst', via virtual interface
 * 'vifi'.  'which_routes' specifies ALL_ROUTES or CHANGED_ROUTES.
 */
int report_chunk(start_rt, vifi, dst)
    register struct rtentry *start_rt;
    vifi_t vifi;
    u_long dst;
{
    register struct rtentry *r;
    register char *p;
    register int i;
    register int nrt = 0;
    int datalen;
    int width;
    u_long mask;
    u_long src;

    src = uvifs[vifi].uv_lcl_addr;
    p = send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN;
    datalen = 0;
    mask = 0;

    for (r = start_rt; r != NULL; r = r->rt_next) {
	/*
	 * If there is no room for this route in the current message,
	 * send it & return how many routes we sent.
	 */
	if (datalen + ((r->rt_originmask == mask) ?
			(width + 1) :
			(r->rt_originwidth + 4)) > MAX_DVMRP_DATA_LEN) {
	    *(p-1) |= 0x80;
	    send_igmp(src, dst, IGMP_DVMRP, DVMRP_REPORT,
			htonl(MROUTED_LEVEL), datalen);
	    return (nrt);
	}
	if(r->rt_originmask != mask) {
	    mask  = r->rt_originmask;
	    width = r->rt_originwidth;
	    if (datalen != 0) *(p-1) |= 0x80;
	    *p++ = ((char *)&mask)[1];
	    *p++ = ((char *)&mask)[2];
	    *p++ = ((char *)&mask)[3];
	    datalen += 3;
	}
	for (i = 0; i < width; ++i)
	    *p++ = ((char *)&(r->rt_origin))[i];

	*p++ = (r->rt_parent == vifi && r->rt_metric != UNREACHABLE) ?
		(char)(r->rt_metric + UNREACHABLE) :  /* "poisoned reverse" */
		(char)(r->rt_metric);
	++nrt;
	datalen += width + 1;
    }
    if (datalen != 0) {
	*(p-1) |= 0x80;
	send_igmp(src, dst, IGMP_DVMRP, DVMRP_REPORT,
			htonl(MROUTED_LEVEL), datalen);
    }
    return (nrt);
}

/*
 * send the next chunk of our routing table to all neighbors.
 */
int report_next_chunk()
{
    register vifi_t vifi;
    register struct uvif *v;
    register struct rtentry *r;
    register struct rtentry *sr;
    register int i, n = 0;
    static int start_rt;

    if (nroutes <= 0)
	return (0);

    /*
     * find this round's starting route.
     */
    for (sr = routing_table, i = start_rt; --i >= 0; ) {
	sr = sr->rt_next;
	if (sr == NULL)
	    sr = routing_table;
    }
    /*
     * send one chunk of routes starting at this round's start to
     * all our neighbors.
     */
    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
	if (v->uv_neighbors != NULL) {
	    n = report_chunk(sr, vifi,
		   (v->uv_flags & VIFF_TUNNEL) ? v->uv_rmt_addr
					      : dvmrp_group);
	}
    }
    if (debug)
	printf("update %d starting at %d of %d\n", n, start_rt, nroutes);
    start_rt = (start_rt + n) % nroutes;
    return (n);
}


/*
 * Print the contents of the routing table on file 'fp'.
 */
void dump_routes(fp)
    FILE *fp;
{
    register struct rtentry *r;
    register int i;

    fprintf(fp,
    "Multicast Routing Table (%u %s)\n%s",
    nroutes, (nroutes == 1) ? "entry" : "entries",
    " Origin-Subnet   From-Gateway    Metric  In-Vif  Out-Vifs\n");

    for (r = routing_table; r != NULL; r = r->rt_next) {

	fprintf(fp, " %-15s %-15s ",
		inet_fmts(r->rt_origin, r->rt_originmask, s1),
		(r->rt_gateway == 0) ? "" : inet_fmt(r->rt_gateway, s2));

	fprintf(fp, (r->rt_metric == UNREACHABLE) ? "  NR " : "%4u ",
		r->rt_metric);

	fprintf(fp, "%7u   ",
		r->rt_parent);

	for (i = 0; i < numvifs; ++i) {
	    if (VIFM_ISSET(i, r->rt_children)) {
		fprintf(fp, " %u%c",
			i, VIFM_ISSET(i, r->rt_leaves) ? '*' : ' ');
	    }
	}
	fprintf(fp, "\n");
    }
    fprintf(fp, "\n");
}