/*
 * 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.
 *
 *
 * $Id: vif.c,v 1.8 1994/08/24 23:54:45 thyagara Exp $
 */


#include "defs.h"


/*
 * Exported variables.
 */
struct uvif	uvifs[MAXVIFS];	/* array of virtual interfaces */
vifi_t		numvifs;	/* number of vifs in use       */
int		vifs_down;	/* 1=>some interfaces are down */
int		udp_socket;	/* Since the honkin' kernel doesn't support */
				/* ioctls on raw IP sockets, we need a UDP  */
				/* socket as well as our IGMP (raw) socket. */
				/* How dumb.                                */

/*
 * Forward declarations.
 */
static void start_vif();
static void stop_vif();

/*
 * Initialize the virtual interfaces.
 */
void init_vifs()
{
    vifi_t vifi;
    struct uvif *v;
    int enabled_vifs, enabled_phyints;

    numvifs = 0;
    vifs_down = FALSE;

    /*
     * Configure the vifs based on the interface configuration of the
     * the kernel and the contents of the configuration file.
     * (Open a UDP socket for ioctl use in the config procedures.)
     */
    if ((udp_socket = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
	log(LOG_ERR, errno, "UDP socket");
    config_vifs_from_kernel();
    config_vifs_from_file();

    /*
     * Quit if there are fewer than two enabled vifs.
     */
    enabled_vifs    = 0;
    enabled_phyints = 0;
    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
	if (!(v->uv_flags & VIFF_DISABLED)) {
	    ++enabled_vifs;
	    if (!(v->uv_flags & VIFF_TUNNEL))
		++enabled_phyints;
	}
    }
    if (enabled_vifs < 2)
	log(LOG_ERR, 0, "can't forward: %s",
	    enabled_vifs == 0 ? "no enabled vifs" : "only one enabled vif");

    if (enabled_phyints == 0)
	log(LOG_WARNING, 0,
	    "no enabled interfaces, forwarding via tunnels only");

    /*
     * Start routing on all virtual interfaces that are not down or
     * administratively disabled.
     */
    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
	if (!(v->uv_flags & VIFF_DISABLED)) {
	    if (!(v->uv_flags & VIFF_DOWN))
		start_vif(vifi);
	    else log(LOG_INFO, 0,
		     "%s is not yet up; vif #%u not in service",
		     v->uv_name, vifi);
	}
    }
}


/*
 * See if any interfaces have changed from up state to down, or vice versa,
 * including any non-multicast-capable interfaces that are in use as local
 * tunnel end-points.  Ignore interfaces that have been administratively
 * disabled.
 */
void check_vif_state()
{
    register vifi_t vifi;
    register struct uvif *v;
    struct ifreq ifr;

    vifs_down = FALSE;
    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {

	if (v->uv_flags & VIFF_DISABLED) continue;

	strncpy(ifr.ifr_name, v->uv_name, IFNAMSIZ);
	if (ioctl(udp_socket, SIOCGIFFLAGS, (char *)&ifr) < 0)
	    log(LOG_ERR, errno,
		"ioctl SIOCGIFFLAGS for %s", ifr.ifr_name);

	if (v->uv_flags & VIFF_DOWN) {
	    if (ifr.ifr_flags & IFF_UP) {
		v->uv_flags &= ~VIFF_DOWN;
		start_vif(vifi);
		log(LOG_INFO, 0,
		    "%s has come up; vif #%u now in service",
		    v->uv_name, vifi);
	    }
	    else vifs_down = TRUE;
	}
	else {
	    if (!(ifr.ifr_flags & IFF_UP)) {
		stop_vif(vifi);
		v->uv_flags |= VIFF_DOWN;
		log(LOG_INFO, 0,
		    "%s has gone down; vif #%u taken out of service",
		    v->uv_name, vifi);
		vifs_down = TRUE;
	    }
	}
    }
}


/*
 * Start routing on the specified virtual interface.
 */
static void start_vif(vifi)
    vifi_t vifi;
{
    struct uvif *v;
    u_long src, dst;
    int i;
    char *p;
    int datalen;
    struct listaddr *nbr;

    v   = &uvifs[vifi];
    src = v->uv_lcl_addr;
    dst = (v->uv_flags & VIFF_TUNNEL) ? v->uv_rmt_addr : dvmrp_group;

    /*
     * Install the interface in the kernel's vif structure.
     */
    k_add_vif(vifi, &uvifs[vifi]);

    /*
     * Update the existing route entries to take into account the new vif.
     */
    add_vif_to_routes(vifi);

    if (!(v->uv_flags & VIFF_TUNNEL)) {
	/*
	 * Join the DVMRP multicast group on the interface.
	 * (This is not strictly necessary, since the kernel promiscuously
	 * receives IGMP packets addressed to ANY IP multicast group while
	 * multicast routing is enabled.  However, joining the group allows
	 * this host to receive non-IGMP packets as well, such as 'pings'.)
	 */
	k_join(dvmrp_group, src);

	/*
	 * Install an entry in the routing table for the subnet to which
	 * the interface is connected.
	 */
	start_route_updates();
	update_route(v->uv_subnet, v->uv_subnetmask, 0, 0, vifi);

	/*
	 * Until neighbors are discovered, assume responsibility for sending
	 * periodic group membership queries to the subnet.  Send the first
	 * query.
	 */
	v->uv_flags |= VIFF_QUERIER;
	send_igmp(src, allhosts_group, IGMP_HOST_MEMBERSHIP_QUERY, 
		  GROUP_EXPIRE_TIME * 10 / ROUTE_MAX_REPORT_DELAY, 0, 0);
	age_old_hosts();
    }

    /*
     * Send a probe via the new vif to look for neighbors.
     */
    p = send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN;
    datalen = 0;

    for (i = 0; i < 4; i++)
	*p++ = ((char *)&(dvmrp_genid))[i];
    datalen += 4;

    /*
     * add the neighbor list on the interface to the message
     */
    nbr = v->uv_neighbors;
    
    while (nbr) {
	for (i = 0; i < 4; i++)
	    *p++ = ((char *)&nbr->al_addr)[i];
	datalen +=4;
	nbr = nbr->al_next;
    }

    send_igmp(src, dst, IGMP_DVMRP, DVMRP_PROBE, 
	      htonl(MROUTED_LEVEL), datalen);
}


/*
 * Stop routing on the specified virtual interface.
 */
static void stop_vif(vifi)
    vifi_t vifi;
{
    struct uvif *v;
    struct listaddr *a;

    v = &uvifs[vifi];

    if (!(v->uv_flags & VIFF_TUNNEL)) {
	/*
	 * Depart from the DVMRP multicast group on the interface.
	 */
	k_leave(dvmrp_group, v->uv_lcl_addr);

	/*
	 * Update the entry in the routing table for the subnet to which
	 * the interface is connected, to take into account the interface
	 * failure.
	 */
	start_route_updates();
	update_route(v->uv_subnet, v->uv_subnetmask, UNREACHABLE, 0, vifi);

	/*
	 * Discard all group addresses.  (No need to tell kernel;
	 * the k_del_vif() call, below, will clean up kernel state.)
	 */
	while (v->uv_groups != NULL) {
	    a = v->uv_groups;
	    v->uv_groups = a->al_next;
	    free((char *)a);
	}

	v->uv_flags &= ~VIFF_QUERIER;
    }

    /*
     * Update the existing route entries to take into account the vif failure.
     */
    delete_vif_from_routes(vifi);

    /*
     * Delete the interface from the kernel's vif structure.
     */
    k_del_vif(vifi);

    /*
     * Discard all neighbor addresses.
     */
    while (v->uv_neighbors != NULL) {
	a = v->uv_neighbors;
	v->uv_neighbors = a->al_next;
	free((char *)a);
    }
}


/*
 * stop routing on all vifs
 */
void stop_all_vifs()
{
    vifi_t vifi;
    struct uvif *v;
    struct listaddr *a;
    struct vif_acl *acl;

    for (vifi = 0; vifi < numvifs; vifi++) {
	v = &uvifs[vifi];
	while (v->uv_groups != NULL) {
	    a = v->uv_groups;
	    v->uv_groups = a->al_next;
	    free((char *)a);
	}
	while (v->uv_neighbors != NULL) {
	    a = v->uv_neighbors;
	    v->uv_neighbors = a->al_next;
	    free((char *)a);
	}
	while (v->uv_acl != NULL) {
	    acl = v->uv_acl;
	    v->uv_acl = acl->acl_next;
	    free((char *)acl);
	}
    }
}


/*
 * Find the virtual interface from which an incoming packet arrived,
 * based on the packet's source and destination IP addresses.
 */
vifi_t find_vif(src, dst)
    register u_long src;
    register u_long dst;
{
    register vifi_t vifi;
    register struct uvif *v;

    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
	if (!(v->uv_flags & (VIFF_DOWN|VIFF_DISABLED))) {
	    if (v->uv_flags & VIFF_TUNNEL) {
		if (src == v->uv_rmt_addr && dst == v->uv_lcl_addr)
		    return(vifi);
	    }
	    else {
		if ((src & v->uv_subnetmask) == v->uv_subnet &&
		    src != v->uv_subnetbcast)
		    return(vifi);
	    }
	}
    }
    return (NO_VIF);
}


age_old_hosts()
{
    register vifi_t vifi;
    register struct uvif *v;
    register struct listaddr *g;
    for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
        /* -*- increment the time since an old report was heard  */
        for (g = v->uv_groups; g != NULL; g = g->al_next)  {
                g->al_last ++;
                if (g->al_last >= OLD_AGE_THRESHOLD){
                         g->al_old = 0;
                         g->al_last = OLD_AGE_THRESHOLD;
                }
        }
    }
}


/*
 * Send group membership queries to all subnets for which I am querier.
 */
void query_groups()
{
    register vifi_t vifi;
    register struct uvif *v;

    for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
	if (v->uv_flags & VIFF_QUERIER) {
	    send_igmp(v->uv_lcl_addr, allhosts_group,
		      IGMP_HOST_MEMBERSHIP_QUERY, 
		      GROUP_EXPIRE_TIME * 10 / ROUTE_MAX_REPORT_DELAY, 0, 0);
	}
    }
    age_old_hosts();
}


/*
 * Process an incoming group membership report.
 */
void accept_group_report(src, dst, group, r_type)
    u_long src, dst, group;
    int  r_type;
{
    register vifi_t vifi;
    register struct uvif *v;
    register struct listaddr *g;

    if ((vifi = find_vif(src, dst)) == NO_VIF ||
	(uvifs[vifi].uv_flags & VIFF_TUNNEL)) {
	log(LOG_INFO, 0,
	    "ignoring group membership report from non-adjacent host %s",
	    inet_fmt(src, s1));
	return;
    }

    v = &uvifs[vifi];

    /*
     * Look for the group in our group list; if found, reset its timer.
     */
    for (g = v->uv_groups; g != NULL; g = g->al_next) {
	if (group == g->al_addr) {
	    if (r_type == IGMP_HOST_NEW_MEMBERSHIP_REPORT) {
		g->al_last = OLD_AGE_THRESHOLD;
		g->al_old = 0;
	    }
	    else {
		g->al_last = 0;
		g->al_old = 1;
	    }

	    /** delete old timer set a timer for expiration **/
	    g->al_timer= GROUP_EXPIRE_TIME;
	    if (g->al_query)
		g->al_query = DeleteTimer(g->al_query);
	    if (g->al_timerid)
		g->al_timerid = DeleteTimer(g->al_timerid);
	    g->al_timerid = SetTimer(vifi, g);	
	    break;
	}
    }

    /*
     * If not found, add it to the list and update kernel cache.
     */
    if (g == NULL) {
	g = (struct listaddr *)malloc(sizeof(struct listaddr));
	if (g == NULL)
	    log(LOG_ERR, 0, "ran out of memory");    /* fatal */

	g->al_addr   = group;
	if (r_type == IGMP_HOST_NEW_MEMBERSHIP_REPORT){
	    g->al_last = OLD_AGE_THRESHOLD;
	    g->al_old = 0;
	}
	else {
	    g->al_last = 0;
	    g->al_old = 1;
	}

	/** set a timer for expiration **/
        g->al_query = 0;
	g->al_timer  = GROUP_EXPIRE_TIME;
	g->al_timerid = SetTimer(vifi, g);
	g->al_next   = v->uv_groups;
	v->uv_groups = g;

	update_lclgrp(vifi, group);
    }

    /* 
     * Check if a graft is necessary for this group
     */
    chkgrp_graft(vifi, group);
}


void leave_group_message( src, dst, group)
    u_long src, dst, group;
{
    register vifi_t vifi;
    register struct uvif *v;
    register struct listaddr *g;

    if ((vifi = find_vif(src, dst)) == NO_VIF ||
	(uvifs[vifi].uv_flags & VIFF_TUNNEL)) {
	log(LOG_INFO, 0,
	    "ignoring group membership report from non-adjacent host %s",
	    inet_fmt(src, s1));
	return;
    }

    v = &uvifs[vifi];

    /*
     * Look for the group in our group list; if found, reset its timer.
     */
    for (g = v->uv_groups; g != NULL; g = g->al_next) {
	if (group == g->al_addr) {
	    log(LOG_DEBUG, 0,
		"[vif.c, _leave_group_message] %d %d \n",
		g->al_old, g->al_query);

	    if (g->al_old)
		return;

	    /** delete old timer set a timer for expiration **/
	    if (g->al_timerid)
		g->al_timerid = DeleteTimer(g->al_timerid);
	    if (g->al_query)
		return;

	    /** send a group specific querry **/
	    g->al_timer = GROUP_EXPIRE_TIME / 10;
	    send_igmp(v->uv_lcl_addr, g->al_addr,
		      IGMP_HOST_MEMBERSHIP_QUERY, 
		      IGMP_MAX_HOST_REPORT_DELAY * 10  / (2*TIMER_INTERVAL),
		      0, 0);
	    g->al_query = SetQueryTimer(g, vifi, g->al_timer / 3 ,
			 	IGMP_MAX_HOST_REPORT_DELAY / 2);
	    g->al_timerid = SetTimer(vifi, g);	
	    break;
	}
    }
}


/*
 * Send a periodic probe on all vifs.
 * Useful to determine one-way interfaces.
 * Detect neighbor loss faster.
 */
void probe_for_neighbors()
{
    register vifi_t vifi;
    register struct uvif *v;
    int i;
    register char *p;
    register int datalen = 0;
    struct listaddr *nbr;

    for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
	if (!(v->uv_flags & (VIFF_DOWN|VIFF_DISABLED))) {

	    p = send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN;

	    for (i = 0; i < 4; i++)
		*p++ = ((char *)&(dvmrp_genid))[i];
	    datalen += 4;

	    /*
	     * add the neighbor list on the interface to the message
	     */
	    nbr = v->uv_neighbors;

	    while (nbr) {
		for (i = 0; i < 4; i++)
		    *p++ = ((char *)&nbr->al_addr)[i];
		datalen +=4;
		nbr = nbr->al_next;
	    }

	    send_igmp(v->uv_lcl_addr,
		      (v->uv_flags & VIFF_TUNNEL) ? v->uv_rmt_addr
		      : dvmrp_group,
		      IGMP_DVMRP, DVMRP_PROBE, htonl(MROUTED_LEVEL), datalen);
	}
    }
}


/*
 * Send a list of all of our neighbors to the requestor, `src'.
 */
void accept_neighbor_request(src, dst)
    u_long src, dst;
{
    vifi_t vifi;
    struct uvif *v;
    u_char *p, *ncount;
    struct listaddr *la;
    int	datalen;
    u_long temp_addr, us, them = src;

    /* Determine which of our addresses to use as the source of our response
     * to this query.
     */
    if (IN_MULTICAST(ntohl(dst))) { /* query sent to a multicast group */
	int udp;		/* find best interface to reply on */
	struct sockaddr_in addr;
	int addrlen = sizeof(addr);

	addr.sin_family = AF_INET;
	addr.sin_len = sizeof addr;
	addr.sin_addr.s_addr = dst;
	addr.sin_port = htons(2000); /* any port over 1024 will do... */
	if ((udp = socket(AF_INET, SOCK_DGRAM, 0)) < 0
	    || connect(udp, (struct sockaddr *) &addr, sizeof(addr)) < 0
	    || getsockname(udp, (struct sockaddr *) &addr, &addrlen) < 0) {
	    log(LOG_WARNING, errno, "Determining local address");
	    close(udp);
	    return;
	}
	close(udp);
	us = addr.sin_addr.s_addr;
    } else			/* query sent to us alone */
	us = dst;	

#define PUT_ADDR(a)	temp_addr = ntohl(a); \
    *p++ = temp_addr >> 24; \
	*p++ = (temp_addr >> 16) & 0xFF; \
	    *p++ = (temp_addr >> 8) & 0xFF; \
		*p++ = temp_addr & 0xFF;

    p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
    datalen = 0;

    for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
	if (v->uv_flags & VIFF_DISABLED)
	    continue;

	ncount = 0;

	for (la = v->uv_neighbors; la; la = la->al_next) {

	    /* Make sure that there's room for this neighbor... */
	    if (datalen + (ncount == 0 ? 4 + 3 + 4 : 4) > MAX_DVMRP_DATA_LEN) {
		send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS,
			  htonl(MROUTED_LEVEL), datalen);
		p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
		datalen = 0;
		ncount = 0;
	    }

	    /* Put out the header for this neighbor list... */
	    if (ncount == 0) {
		PUT_ADDR(v->uv_lcl_addr);
		*p++ = v->uv_metric;
		*p++ = v->uv_threshold;
		ncount = p;
		*p++ = 0;
		datalen += 4 + 3;
	    }

	    PUT_ADDR(la->al_addr);
	    datalen += 4;
	    (*ncount)++;
	}
    }

    if (datalen != 0)
	send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS, htonl(MROUTED_LEVEL),
		  datalen);
}

/*
 * Send a list of all of our neighbors to the requestor, `src'.
 */
void accept_neighbor_request2(src, dst)
    u_long src, dst;
{
    vifi_t vifi;
    struct uvif *v;
    u_char *p, *ncount;
    struct listaddr *la;
    int	datalen;
    u_long temp_addr, us, them = src;

    /* Determine which of our addresses to use as the source of our response
     * to this query.
     */
    if (IN_MULTICAST(ntohl(dst))) { /* query sent to a multicast group */
	int udp;		/* find best interface to reply on */
	struct sockaddr_in addr;
	int addrlen = sizeof(addr);

	addr.sin_family = AF_INET;
	addr.sin_len = sizeof addr;
	addr.sin_addr.s_addr = dst;
	addr.sin_port = htons(2000); /* any port over 1024 will do... */
	if ((udp = socket(AF_INET, SOCK_DGRAM, 0)) < 0
	    || connect(udp, (struct sockaddr *) &addr, sizeof(addr)) < 0
	    || getsockname(udp, (struct sockaddr *) &addr, &addrlen) < 0) {
	    log(LOG_WARNING, errno, "Determining local address");
	    close(udp);
	    return;
	}
	close(udp);
	us = addr.sin_addr.s_addr;
    } else			/* query sent to us alone */
	us = dst;	

    p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
    datalen = 0;

    for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {
	register u_short vflags = v->uv_flags;
	register u_char rflags = 0;
	if (vflags & VIFF_TUNNEL)
	    rflags |= DVMRP_NF_TUNNEL;
	if (vflags & VIFF_SRCRT)
	    rflags |= DVMRP_NF_SRCRT;
	if (vflags & VIFF_DOWN)
	    rflags |= DVMRP_NF_DOWN;
	if (vflags & VIFF_DISABLED)
	    rflags |= DVMRP_NF_DISABLED;
	if (vflags & VIFF_QUERIER)
	    rflags |= DVMRP_NF_QUERIER;
	ncount = 0;
	la = v->uv_neighbors;
	if (la == NULL) {
	    /*
	     * include down & disabled interfaces and interfaces on
	     * leaf nets.
	     */
	    if (rflags & DVMRP_NF_TUNNEL)
		rflags |= DVMRP_NF_DOWN;
	    if (datalen > MAX_DVMRP_DATA_LEN - 12) {
		send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS2,
			  htonl(MROUTED_LEVEL), datalen);
		p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
		datalen = 0;
	    }
	    *(u_int*)p = v->uv_lcl_addr;
	    p += 4;
	    *p++ = v->uv_metric;
	    *p++ = v->uv_threshold;
	    *p++ = rflags;
	    *p++ = 1;
	    *(u_int*)p =  v->uv_rmt_addr;
	    p += 4;
	    datalen += 12;
	} else {
	    for ( ; la; la = la->al_next) {
		/* Make sure that there's room for this neighbor... */
		if (datalen + (ncount == 0 ? 4+4+4 : 4) > MAX_DVMRP_DATA_LEN) {
		    send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS2,
			      htonl(MROUTED_LEVEL), datalen);
		    p = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);
		    datalen = 0;
		    ncount = 0;
		}
		/* Put out the header for this neighbor list... */
		if (ncount == 0) {
		    *(u_int*)p = v->uv_lcl_addr;
		    p += 4;
		    *p++ = v->uv_metric;
		    *p++ = v->uv_threshold;
		    *p++ = rflags;
		    ncount = p;
		    *p++ = 0;
		    datalen += 4 + 4;
		}
		*(u_int*)p = la->al_addr;
		p += 4;
		datalen += 4;
		(*ncount)++;
	    }
	}
    }
    if (datalen != 0)
	send_igmp(us, them, IGMP_DVMRP, DVMRP_NEIGHBORS2, htonl(MROUTED_LEVEL),
		  datalen);
}


/*
 * Process an incoming neighbor-list message.
 */
void accept_neighbors(src, dst, p, datalen, level)
    u_long src, dst, level;
    char *p;
    int datalen;
{
    log(LOG_INFO, 0, "ignoring spurious DVMRP neighbor list from %s to %s",
	inet_fmt(src, s1), inet_fmt(dst, s2));
}


/*
 * Process an incoming neighbor-list message.
 */
void accept_neighbors2(src, dst, p, datalen, level)
    u_long src, dst, level;
    char *p;
    int datalen;
{
    log(LOG_INFO, 0, "ignoring spurious DVMRP neighbor list2 from %s to %s",
	inet_fmt(src, s1), inet_fmt(dst, s2));
}


/*
 * Update the neighbor entry for neighbor 'addr' on vif 'vifi'.
 * 'msgtype' is the type of DVMRP message received from the neighbor.
 * Return TRUE if 'addr' is a valid neighbor, FALSE otherwise.
 */
int update_neighbor(vifi, addr, msgtype, p, datalen, level)
    vifi_t vifi;
    u_long addr;
    int msgtype;
    char *p;
    int datalen;
    u_long level;
{
    register struct uvif *v;
    register struct listaddr *n;
    u_long genid;
    u_long router;
    int he_hears_me = TRUE;

    v = &uvifs[vifi];

    /*
     * Confirm that 'addr' is a valid neighbor address on vif 'vifi'.
     * IT IS ASSUMED that this was preceded by a call to find_vif(), which
     * checks that 'addr' is either a valid remote tunnel endpoint or a
     * non-broadcast address belonging to a directly-connected subnet.
     * Therefore, here we check only that 'addr' is not our own address
     * (due to an impostor or erroneous loopback) or an address of the form
     * {subnet,0} ("the unknown host").  These checks are not performed in
     * find_vif() because those types of address are acceptable for some
     * types of IGMP message (such as group membership reports).
     */
    if (!(v->uv_flags & VIFF_TUNNEL) &&
	(addr == v->uv_lcl_addr ||
	 addr == v->uv_subnet )) {
	log(LOG_WARNING, 0,
	    "received DVMRP message from 'the unknown host' or self: %s",
	    inet_fmt(addr, s1));
	return (FALSE);
    }

    /*
     * If we have received a route report from a neighbor, and we believed
     * that we had no neighbors on this vif, send a full route report to
     * all neighbors on the vif.
     */

    if (msgtype == DVMRP_REPORT && v->uv_neighbors == NULL)
	report(ALL_ROUTES, vifi,
	       (v->uv_flags & VIFF_TUNNEL) ? addr : dvmrp_group);

    /*
     * Check if the router gen-ids are the same.
     * Need to reset the prune state of the router if not.
     */
    if (msgtype == DVMRP_PROBE) {
	int i;

	if (datalen < 4) {
	    log(LOG_WARNING, 0,
		"received truncated probe message from %s",
		inet_fmt(addr, s1));
	    return;
	}

	for (i = 0; i < 4; i++)
	    ((char *)&genid)[i] = *p++;
	datalen -=4;

	/* 
	 * loop through router list and check for one-way ifs.
	 */

	he_hears_me = FALSE;

	while (datalen > 0) {
	    if (datalen < 4) {
		log(LOG_WARNING, 0,
		    "received truncated probe message from %s",
		    inet_fmt(addr, s1));
		return;
	    }
	    for (i = 0; i < 4; i++)
		((char *)&router)[i] = *p++;
	    datalen -= 4;
	    if (router == v->uv_lcl_addr) {
		he_hears_me = TRUE;
		break;
	    }
	}
    }
    /*
     * Look for addr in list of neighbors; if found, reset its timer.
     */
    for (n = v->uv_neighbors; n != NULL; n = n->al_next) {
	if (addr == n->al_addr) {
	    n->al_timer = 0;

	    /* If probe message and version no >= 3.3 check genid */
	    if (msgtype == DVMRP_PROBE && 
		((n->al_pv >= 3 && n->al_mv > 2) || n->al_pv > 3)) {
		if (he_hears_me == TRUE && v->uv_flags & VIFF_ONEWAY)
		    v->uv_flags &= ~VIFF_ONEWAY;

		if (he_hears_me == FALSE)
		    v->uv_flags |= VIFF_ONEWAY;

		if ((n->al_genid != 0) && (n->al_genid != genid)) {
		    log(LOG_DEBUG, 0,
			"old:%d new:%dreset neighbor %s", 
			n->al_genid, genid, inet_fmt(addr, s1));

		    reset_neighbor_state(vifi, addr);
		    n->al_genid = genid;
		    /* need to do a full route report here */
		    break;
		}

		/* recurring probe - so no need to do a route report */
		return FALSE;
	    }
	    break;
	}
    }

    /*
     * If not found, add it to the list.  If the neighbor has a lower
     * IP address than me, yield querier duties to it.
     */
    if (n == NULL) {
	n = (struct listaddr *)malloc(sizeof(struct listaddr));
	if (n == NULL)
	    log(LOG_ERR, 0, "ran out of memory");    /* fatal */

	n->al_addr      = addr;
	n->al_pv	= level & 0xff;
	n->al_mv	= (level >> 8) & 0xff;
	if (msgtype == DVMRP_PROBE)
	    n->al_genid = genid;
	else
	    n->al_genid = 0;

	n->al_timer     = 0;
	n->al_next      = v->uv_neighbors;
	v->uv_neighbors = n;

	if (!(v->uv_flags & VIFF_TUNNEL) &&
	    ntohl(addr) < ntohl(v->uv_lcl_addr))
	    v->uv_flags &= ~VIFF_QUERIER;
    }

    return (TRUE);
}


/*
 * On every timer interrupt, advance the timer in each neighbor and
 * group entry on every vif.
 */
void age_vifs()
{
    register vifi_t vifi;
    register struct uvif *v;
    register struct listaddr *a, *prev_a, *n;
    register u_long addr;

    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v ) {

	for (prev_a = (struct listaddr *)&(v->uv_neighbors),
	     a = v->uv_neighbors;
	     a != NULL;
	     prev_a = a, a = a->al_next) {

	    if ((a->al_timer += TIMER_INTERVAL) < NEIGHBOR_EXPIRE_TIME)
		continue;

	    /*
	     * Neighbor has expired; delete it from the neighbor list,
	     * delete it from the 'dominants' and 'subordinates arrays of
	     * any route entries and assume querier duties unless there is
	     * another neighbor with a lower IP address than mine.
	     */
	    addr = a->al_addr;
	    prev_a->al_next = a->al_next;
	    free((char *)a);
	    a = prev_a;

	    delete_neighbor_from_routes(addr, vifi);

	    if (!(v->uv_flags & VIFF_TUNNEL)) {
		v->uv_flags |= VIFF_QUERIER;
		for (n = v->uv_neighbors; n != NULL; n = n->al_next) {
		    if (ntohl(n->al_addr) < ntohl(v->uv_lcl_addr)) {
			v->uv_flags &= ~VIFF_QUERIER;
			break;
		    }
		}
	    }
	}
    }
}


/*
 * Print the contents of the uvifs array on file 'fp'.
 */
void dump_vifs(fp)
    FILE *fp;
{
    register vifi_t vifi;
    register struct uvif *v;
    register struct listaddr *a;
    struct sioc_vif_req v_req;

    fprintf(fp,
    "\nVirtual Interface Table\n%s",
    "Vif  Name  Local-Address                            ");
    fprintf(fp,
    "M  Thr  Rate   Flags\n");

    for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++) {

	fprintf(fp, "%2u %6s  %-15s %6s: %-15s %2u %3u  %5u  ",
		vifi,
		v->uv_name,
		inet_fmt(v->uv_lcl_addr, s1),
		(v->uv_flags & VIFF_TUNNEL) ?
			"tunnel":
			"subnet",
		(v->uv_flags & VIFF_TUNNEL) ?
			inet_fmt(v->uv_rmt_addr, s2) :
			inet_fmts(v->uv_subnet, v->uv_subnetmask, s3),
		v->uv_metric,
		v->uv_threshold,
		v->uv_rate_limit);

	if (v->uv_flags & VIFF_ONEWAY)   fprintf(fp, " one-way");
	if (v->uv_flags & VIFF_DOWN)     fprintf(fp, " down");
	if (v->uv_flags & VIFF_DISABLED) fprintf(fp, " disabled");
	if (v->uv_flags & VIFF_QUERIER)  fprintf(fp, " querier");
	if (v->uv_flags & VIFF_SRCRT)    fprintf(fp, " src-rt");
	fprintf(fp, "\n");

	if (v->uv_neighbors != NULL) {
	    fprintf(fp, "                            peers: %s (%d.%d)\n",
		    inet_fmt(v->uv_neighbors->al_addr, s1),
		    v->uv_neighbors->al_pv, v->uv_neighbors->al_mv);
	    for (a = v->uv_neighbors->al_next; a != NULL; a = a->al_next) {
		fprintf(fp, "                                   %s (%d.%d)\n",
			inet_fmt(a->al_addr, s1), a->al_pv, a->al_mv);
	    }
	}

	if (v->uv_groups != NULL) {
	    fprintf(fp, "                           groups: %-15s\n",
		    inet_fmt(v->uv_groups->al_addr, s1));
	    for (a = v->uv_groups->al_next; a != NULL; a = a->al_next) {
		fprintf(fp, "                                   %-15s\n",
			inet_fmt(a->al_addr, s1));
	    }
	}
	if (v->uv_acl != NULL) {
	    struct vif_acl *acl;

	    fprintf(fp, "                          boundaries: %-15s\n",
		    inet_fmts(v->uv_acl->acl_addr, v->uv_acl->acl_mask, s1));
	    for (acl = v->uv_acl->acl_next; acl != NULL; acl = acl->acl_next) {
		fprintf(fp, "                                 : %-15s\n",
			inet_fmts(acl->acl_addr, acl->acl_mask, s1));
	    }
	}
	v_req.vifi = vifi;
	if (ioctl(udp_socket, SIOCGETVIFCNT, (char *)&v_req) < 0) {
	    log(LOG_WARNING, 0,
		"SIOCGETVIFCNT fails");
	}
	else {
	    fprintf(fp, "                         pkts in : %d\n",
		    v_req.icount);
	    fprintf(fp, "                         pkts out: %d\n",
		    v_req.ocount);
	}
	fprintf(fp, "\n");
    }
    fprintf(fp, "\n");
}


/****           the timeout routines    ********/

typedef struct {
        vifi_t  vifi;
        struct listaddr *g;
	int    q_time;
} cbk_t;

static cbk_t *cbk;

DelVif(cbk)
cbk_t *cbk;
{
	 /* -*- make the list consistent */
	 register vifi_t   vifi = cbk->vifi;
	 register struct uvif *v;
	 register struct listaddr *a, *prev_a, *g = cbk->g;

	 v = &uvifs[vifi];

         for (prev_a = (struct listaddr *)&(v->uv_groups),
             a = v->uv_groups;
             a != NULL;
             prev_a = a, a = a->al_next) {

            if (a != g) continue;

            /*
             * Group has expired
             * delete all kernel cache entries with this group
             */
	    if( g->al_query) DeleteTimer(g->al_query);
            delete_lclgrp(vifi, a->al_addr);

            prev_a->al_next = a->al_next;
            free((char *)a);
            a = prev_a;
         }

         free(cbk);
}


SetTimer( vifi, g)
        vifi_t vifi;  struct listaddr *g;
{
        cbk = (cbk_t *) malloc(sizeof(cbk_t));
        cbk->g = g;
        cbk->vifi = vifi;
        return timer_setTimer(g->al_timer,DelVif,cbk);
}

DeleteTimer( id)
int id;
{
        timer_clearTimer(id);
	return 0;
}

SendQuery(cbk)
cbk_t *cbk;
{
	 register struct uvif *v = &uvifs[cbk->vifi];
            send_igmp(v->uv_lcl_addr, cbk->g->al_addr,
                      IGMP_HOST_MEMBERSHIP_QUERY,
                      cbk->q_time * 10 /  TIMER_INTERVAL, 0, 0);
	    cbk->g->al_query = 0;
	    free(cbk);
}

SetQueryTimer(g , vifi, to_expire, q_time)
	struct listaddr *g;  vifi_t vifi;
	int to_expire, q_time;
{
        cbk = (cbk_t *) malloc(sizeof(cbk_t));
        cbk->g = g;
        cbk->q_time = q_time; cbk-> vifi = vifi;
        return timer_setTimer(to_expire,SendQuery,cbk);
}