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[netbsd-mini2440.git] / usr.sbin / mrouted / vif.c

/*      $NetBSD: vif.c,v 1.17 2006/05/25 01:38:41 christos Exp $        */

/*
 * 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.
 */


#include "defs.h"
#include <fcntl.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             phys_vif;       /* An enabled vif                           */
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.                                */
int             vifs_with_neighbors;    /* == 1 if I am a leaf              */

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

/*
 * Forward declarations.
 */
static void start_vif(vifi_t vifi);
static void start_vif2(vifi_t vifi);
static void stop_vif(vifi_t vifi);
static void age_old_hosts(void);
static void send_probe_on_vif(struct uvif *v);
static int info_version(char *p, size_t);
static void DelVif(void *arg);
static int SetTimer(vifi_t vifi, struct listaddr *g);
static int DeleteTimer(int id);
static void SendQuery(void *arg);
static int SetQueryTimer(struct listaddr *g, vifi_t vifi, int to_expire,
                         int q_time);


/*
 * Initialize the virtual interfaces, but do not install
 * them in the kernel.  Start routing on all vifs that are
 * not down or disabled.
 */
void
init_vifs(void)
{
    vifi_t vifi;
    struct uvif *v;
    int enabled_vifs, enabled_phyints;
    extern char *configfilename;

    numvifs = 0;
    vifs_with_neighbors = 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)
        logit(LOG_ERR, errno, "UDP socket");
    logit(LOG_INFO,0,"Getting vifs from kernel interfaces");
    config_vifs_from_kernel();
    logit(LOG_INFO,0,"Getting vifs from %s",configfilename);
    config_vifs_from_file();

    /*
     * Quit if there are fewer than two enabled vifs.
     */
    enabled_vifs    = 0;
    enabled_phyints = 0;
    phys_vif        = -1;
    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
        if (!(v->uv_flags & VIFF_DISABLED)) {
            ++enabled_vifs;
            if (!(v->uv_flags & VIFF_TUNNEL)) {
                if (phys_vif == -1)
                    phys_vif = vifi;
                ++enabled_phyints;
            }
        }
    }
    if (enabled_vifs < 2)
        logit(LOG_ERR, 0, "can't forward: %s",
            enabled_vifs == 0 ? "no enabled vifs" : "only one enabled vif");

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

    logit(LOG_INFO, 0, "Installing vifs in mrouted...");
    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
        if (!(v->uv_flags & VIFF_DISABLED)) {
            if (!(v->uv_flags & VIFF_DOWN)) {
                if (v->uv_flags & VIFF_TUNNEL)
                    logit(LOG_INFO, 0, "vif #%d, tunnel %s -> %s", vifi,
                                inet_fmt(v->uv_lcl_addr),
                                inet_fmt(v->uv_rmt_addr));
                else
                    logit(LOG_INFO, 0, "vif #%d, phyint %s", vifi,
                                inet_fmt(v->uv_lcl_addr));
                start_vif2(vifi);
            } else logit(LOG_INFO, 0,
                     "%s is not yet up; vif #%u not in service",
                     v->uv_name, vifi);
        }
    }
}

/*
 * Start routing on all virtual interfaces that are not down or
 * administratively disabled.
 */
void
init_installvifs(void)
{
    vifi_t vifi;
    struct uvif *v;

    logit(LOG_INFO, 0, "Installing vifs in kernel...");
    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
        if (!(v->uv_flags & VIFF_DISABLED)) {
            if (!(v->uv_flags & VIFF_DOWN)) {
                if (v->uv_flags & VIFF_TUNNEL)
                    logit(LOG_INFO, 0, "vif #%d, tunnel %s -> %s", vifi,
                                inet_fmt(v->uv_lcl_addr),
                                inet_fmt(v->uv_rmt_addr));
                else
                    logit(LOG_INFO, 0, "vif #%d, phyint %s", vifi,
                                inet_fmt(v->uv_lcl_addr));
                k_add_vif(vifi, &uvifs[vifi]);
            } else logit(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(void)
{
    vifi_t vifi;
    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)
            logit(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);
                logit(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;
                logit(LOG_INFO, 0,
                    "%s has gone down; vif #%u taken out of service",
                    v->uv_name, vifi);
                vifs_down = TRUE;
            }
        }
    }
}

/*
 * Send a probe message on vif v
 */
static void
send_probe_on_vif(struct uvif *v)
{
    char *p;
    int datalen = 0;
    struct listaddr *nbr;
    int i;

    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 |
              ((v->uv_flags & VIFF_LEAF) ? 0 : LEAF_FLAGS)),
              datalen);
}

/*
 * Add a vifi to the kernel and start routing on it.
 */
static void
start_vif(vifi_t vifi)
{
    /*
     * Install the interface in the kernel's vif structure.
     */
    k_add_vif(vifi, &uvifs[vifi]);

    start_vif2(vifi);
}

/*
 * Add a vifi to all the user-level data structures but don't add
 * it to the kernel yet.
 */
static void
start_vif2(vifi_t vifi)
{
    struct uvif *v;
    u_int32_t src;
    struct phaddr *p;

    v   = &uvifs[vifi];
    src = v->uv_lcl_addr;

    /*
     * 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);

        /*
         * Join the ALL-ROUTERS multicast group on the interface.
         * This allows mtrace requests to loop back if they are run
         * on the multicast router.
         */
        k_join(allrtrs_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);
        for (p = v->uv_addrs; p; p = p->pa_next) {
            start_route_updates();
            update_route(p->pa_subnet, p->pa_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, 
              (v->uv_flags & VIFF_IGMPV1) ? 0 :
              IGMP_MAX_HOST_REPORT_DELAY * IGMP_TIMER_SCALE, 0, 0);
        age_old_hosts();
    }

    v->uv_leaf_timer = LEAF_CONFIRMATION_TIME;

    /*
     * Send a probe via the new vif to look for neighbors.
     */
    send_probe_on_vif(v);
}

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

    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);

        /*
         * Depart from the ALL-ROUTERS multicast group on the interface.
         */
        k_leave(allrtrs_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);
        for (p = v->uv_addrs; p; p = p->pa_next) {
            start_route_updates();
            update_route(p->pa_subnet, p->pa_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.
     */
    if (v->uv_neighbors)
        vifs_with_neighbors--;

    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(void)
{
    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(u_int32_t src, u_int32_t dst)
{
    vifi_t vifi;
    struct uvif *v;
    struct phaddr *p;

    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 &&
                    ((v->uv_subnetmask == 0xffffffff) ||
                     (src != v->uv_subnetbcast)))
                    return(vifi);
                for (p=v->uv_addrs; p; p=p->pa_next) {
                    if ((src & p->pa_subnetmask) == p->pa_subnet &&
                        ((p->pa_subnetmask == 0xffffffff) ||
                         (src != p->pa_subnetbcast)))
                        return(vifi);
                }
            }
        }
    }
    return (NO_VIF);
}

static void
age_old_hosts(void)
{
    vifi_t vifi;
    struct uvif *v;
    struct listaddr *g;

    /*
     * Decrement the old-hosts-present timer for each
     * active group on each vif.
     */
    for (vifi = 0, v = uvifs; vifi < numvifs; vifi++, v++)
        for (g = v->uv_groups; g != NULL; g = g->al_next)
            if (g->al_old)
                g->al_old--;
}


/*
 * Send group membership queries to all subnets for which I am querier.
 */
void
query_groups(void)
{
    vifi_t vifi;
    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, 
                      (v->uv_flags & VIFF_IGMPV1) ? 0 :
                      IGMP_MAX_HOST_REPORT_DELAY * IGMP_TIMER_SCALE, 0, 0);
        }
    }
    age_old_hosts();
}

/*
 * Process an incoming host membership query
 */
void
accept_membership_query(u_int32_t src, u_int32_t dst, u_int32_t group, int tmo)
{
    vifi_t vifi;
    struct uvif *v;

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

    v = &uvifs[vifi];

    /*
     * If we consider ourselves the querier for this vif, but hear a
     * query from a router with a lower IP address, yield to them.
     *
     * This is done here as well as in the neighbor discovery in case
     * there is a querier that doesn't speak DVMRP.
     *
     * XXX If this neighbor doesn't speak DVMRP, then we need to create
     * some neighbor state for him so that we can time him out!
     */
    if ((v->uv_flags & VIFF_QUERIER) &&
        (ntohl(src) < ntohl(v->uv_lcl_addr))) {
            v->uv_flags &= ~VIFF_QUERIER;

    }
}

/*
 * Process an incoming group membership report.
 */
void
accept_group_report(u_int32_t src, u_int32_t dst, u_int32_t group, int r_type)
{
    vifi_t vifi;
    struct uvif *v;
    struct listaddr *g;

    if ((vifi = find_vif(src, dst)) == NO_VIF ||
        (uvifs[vifi].uv_flags & VIFF_TUNNEL)) {
        logit(LOG_INFO, 0,
            "ignoring group membership report from non-adjacent host %s",
            inet_fmt(src));
        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_v1_HOST_MEMBERSHIP_REPORT)
                g->al_old = OLD_AGE_THRESHOLD;
#ifdef SNMP
            g->al_genid = src;
#endif /* SNMP */

            /** delete old timers, 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) {
            logit(LOG_ERR, 0, "ran out of memory");    /* fatal */
            return;
        }

        g->al_addr   = group;
        if (r_type == IGMP_v2_HOST_MEMBERSHIP_REPORT)
            g->al_old = 0;
        else
            g->al_old = OLD_AGE_THRESHOLD;
#ifdef SNMP
        g->al_genid = src;
#endif

        /** set a timer for expiration **/
        g->al_query = 0;
        g->al_timer  = GROUP_EXPIRE_TIME;
        time(&g->al_ctime);
        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
accept_leave_message(u_int32_t src, u_int32_t dst, u_int32_t group)
{
    vifi_t vifi;
    struct uvif *v;
    struct listaddr *g;

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

    v = &uvifs[vifi];

    if (!(v->uv_flags & VIFF_QUERIER) || (v->uv_flags & VIFF_IGMPV1))
        return;

    /*
     * Look for the group in our group list in order to set up a short-timeout
     * query.
     */
    for (g = v->uv_groups; g != NULL; g = g->al_next) {
        if (group == g->al_addr) {
            logit(LOG_DEBUG, 0,
                "[vif.c, _accept_leave_message] %d %ld\n",
                g->al_old, g->al_query);

            /* Ignore the leave message if there are old hosts present */
            if (g->al_old)
                return;

            /* still waiting for a reply to a query, ignore the leave */
            if (g->al_query)
                return;

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

            /** send a group specific querry **/
            g->al_timer = LEAVE_EXPIRE_TIME;
            send_igmp(v->uv_lcl_addr, g->al_addr,
                      IGMP_HOST_MEMBERSHIP_QUERY, 
                      LEAVE_EXPIRE_TIME / 3 * IGMP_TIMER_SCALE,
                      g->al_addr, 0);
            g->al_query = SetQueryTimer(g, vifi, g->al_timer / 3,
                                LEAVE_EXPIRE_TIME / 3 * IGMP_TIMER_SCALE);
            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(void)
{
    vifi_t vifi;
    struct uvif *v;

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


/*
 * Send a list of all of our neighbors to the requestor, `src'.
 */
void
accept_neighbor_request(u_int32_t src, u_int32_t dst)
{
    vifi_t vifi;
    struct uvif *v;
    u_char *p, *ncount;
    struct listaddr *la;
    int datalen;
    u_int32_t 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;
        socklen_t addrlen = sizeof(addr);

        memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
#if (defined(BSD) && (BSD >= 199103))
        addr.sin_len = sizeof addr;
#endif
        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) {
            logit(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(u_int32_t src, u_int32_t dst)
{
    vifi_t vifi;
    struct uvif *v;
    u_char *p, *ncount;
    struct listaddr *la;
    int datalen;
    u_int32_t 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;
        socklen_t addrlen = sizeof(addr);

        memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
#if (defined(BSD) && (BSD >= 199103))
        addr.sin_len = sizeof addr;
#endif
        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) {
            logit(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++) {
        u_short vflags = v->uv_flags;
        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;
        if (vflags & VIFF_LEAF)
            rflags |= DVMRP_NF_LEAF;
        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);
}

void
accept_info_request(u_int32_t src, u_int32_t dst, u_char *p, int datalen)
{
    u_char *q;
    int len;
    int outlen = 0;

    q = (u_char *) (send_buf + MIN_IP_HEADER_LEN + IGMP_MINLEN);

    /* To be general, this must deal properly with breaking up over-sized
     * packets.  That implies passing a length to each function, and
     * allowing each function to request to be called again.  Right now,
     * we're only implementing the one thing we are positive will fit into
     * a single packet, so we wimp out.
     */
    while (datalen > 0) {
        len = 0;
        switch (*p) {
            case DVMRP_INFO_VERSION:
                len = info_version((char *)q,
                    send_buflen - MIN_IP_HEADER_LEN - IGMP_MINLEN);
                break;

            case DVMRP_INFO_NEIGHBORS:
            default:
                logit(LOG_INFO, 0, "ignoring unknown info type %d", *p);
                break;
        }
        *(q+1) = len++;
        outlen += len * 4;
        q += len * 4;
        len = (*(p+1) + 1) * 4;
        p += len;
        datalen -= len;
    }

    if (outlen != 0)
        send_igmp(INADDR_ANY, src, IGMP_DVMRP, DVMRP_INFO_REPLY,
                        htonl(MROUTED_LEVEL), outlen);
}

/*
 * Information response -- return version string
 */
static int
info_version(char *p, size_t l)
{
    int len;
    extern char versionstring[];

    if (l < 4 + strlen(versionstring) + 1)
       return -1;
    p[0] = DVMRP_INFO_VERSION;
    /* skip over length */
    p[2] = 0;   /* zero out */
    p[3] = 0;   /* reserved fields */
    strlcpy(p + 4, versionstring, l - 4);

    len = strlen(versionstring);
    return ((len + 3) / 4);
}

/*
 * Process an incoming neighbor-list message.
 */
void
accept_neighbors(u_int32_t src, u_int32_t dst, u_char *p, int datalen,
                 u_int32_t level)
{
    logit(LOG_INFO, 0, "ignoring spurious DVMRP neighbor list from %s to %s",
        inet_fmt(src), inet_fmt(dst));
}


/*
 * Process an incoming neighbor-list message.
 */
void
accept_neighbors2(u_int32_t src, u_int32_t dst, u_char *p, int datalen,
                  u_int32_t level)
{
    logit(LOG_INFO, 0, "ignoring spurious DVMRP neighbor list2 from %s to %s",
        inet_fmt(src), inet_fmt(dst));
}

/*
 * Process an incoming info reply message.
 */
void
accept_info_reply(u_int32_t src, u_int32_t dst, u_char *p, int datalen)
{
    logit(LOG_INFO, 0, "ignoring spurious DVMRP info reply from %s to %s",
        inet_fmt(src), inet_fmt(dst));
}


/*
 * 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_t vifi, u_int32_t addr, int msgtype, char *p, int datalen, u_int32_t level)
{
    struct uvif *v;
    struct listaddr *n;
    u_int32_t genid = 0;
    u_int32_t router;
    u_int32_t send_tables = 0;
    int do_reset = FALSE;
    int nflags;

    v = &uvifs[vifi];
    nflags = (level >> 16) & 0xff;

    /*
     * 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 )) {
        logit(LOG_WARNING, 0,
            "received DVMRP message from 'the unknown host' or self: %s",
            inet_fmt(addr));
        return (FALSE);
    }

    /*
     * Look for addr in list of neighbors.
     */
    for (n = v->uv_neighbors; n != NULL; n = n->al_next) {
        if (addr == n->al_addr) {
            break;
        }
    }

    /*
     * Found it.  Reset its timer, and check for a version change
     */
    if (n) {
        n->al_timer = 0;

        /*
         * update the neighbors version and protocol number
         * if changed => router went down and came up, 
         * so take action immediately.
         */
        if ((n->al_pv != (level & 0xff)) ||
            (n->al_mv != ((level >> 8) & 0xff))) {

            do_reset = TRUE;
            logit(LOG_DEBUG, 0,
                "version change neighbor %s [old:%d.%d, new:%d.%d]",
                inet_fmt(addr),
                n->al_pv, n->al_mv, level&0xff, (level >> 8) & 0xff);
            
            n->al_pv = level & 0xff;
            n->al_mv = (level >> 8) & 0xff;
        }
    } else {
        /*
         * If not found, add it to the list.  If the neighbor has a lower
         * IP address than me, yield querier duties to it.
         */
        logit(LOG_DEBUG, 0, "New neighbor %s on vif %d v%d.%d nf 0x%02x",
            inet_fmt(addr), vifi,
            level & 0xff, (level >> 8) & 0xff, (level >> 16) & 0xff);

        n = (struct listaddr *)malloc(sizeof(struct listaddr));
        if (n == NULL) {
            logit(LOG_ERR, 0, "ran out of memory");    /* fatal */
            return FALSE;
        }

        n->al_addr      = addr;
        n->al_pv        = level & 0xff;
        n->al_mv        = (level >> 8) & 0xff;
        n->al_genid     = 0;

        time(&n->al_ctime);
        n->al_timer     = 0;
        n->al_next      = v->uv_neighbors;

        /*
         * If we thought that we had no neighbors on this vif, send a route
         * report to the vif.  If this is just a new neighbor on the same
         * vif, send the route report just to the new neighbor.
         */
        if (v->uv_neighbors == NULL) {
            send_tables = (v->uv_flags & VIFF_TUNNEL) ? addr : dvmrp_group;
            vifs_with_neighbors++;
        } else {
            send_tables = addr;
        }

        v->uv_neighbors = n;

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

    /*
     * Check if the router gen-ids are the same.
     * Need to reset the prune state of the router if not.
     * Also check for one-way interfaces by seeing if we are in our
     * neighbor's list of known routers.
     */
    if (msgtype == DVMRP_PROBE) {

        /* Check genid neighbor flag.  Also check version number; 3.3 and
         * 3.4 didn't set this flag. */
        if ((((level >> 16) & 0xff) & NF_GENID) ||
            (((level & 0xff) == 3) && (((level >> 8) & 0xff) > 2))) {

            int i;

            if (datalen < 4) {
                logit(LOG_WARNING, 0,
                    "received truncated probe message from %s (len %d)",
                    inet_fmt(addr), datalen);
                return (FALSE);
            }

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

            if (n->al_genid == 0)
                n->al_genid = genid;
            else if (n->al_genid != genid) {
                logit(LOG_DEBUG, 0,
                    "new genid neigbor %s on vif %d [old:%x, new:%x]",
                    inet_fmt(addr), vifi, n->al_genid, genid);

                n->al_genid = genid;
                do_reset = TRUE;
            }
            
            /* 
             * loop through router list and check for one-way ifs.
             */
            
            v->uv_flags |= VIFF_ONEWAY;
            
            while (datalen > 0) {
                if (datalen < 4) {
                    logit(LOG_WARNING, 0,
                        "received truncated probe message from %s (len %d)",
                        inet_fmt(addr), datalen);
                    return (FALSE);
                }
                for (i = 0; i < 4; i++)
                  ((char *)&router)[i] = *p++;
                datalen -= 4;
                if (router == v->uv_lcl_addr) {
                    v->uv_flags &= ~VIFF_ONEWAY;
                    break;
                }
            }
        }
    }
    if (n->al_flags != nflags) {
        n->al_flags = nflags;

        if (n->al_flags & NF_LEAF) {
            /*XXX If we have non-leaf neighbors then we know we shouldn't
             * mark this vif as a leaf.  For now we just count on other
             * probes and/or reports resetting the timer. */
            if (!v->uv_leaf_timer)
                v->uv_leaf_timer = LEAF_CONFIRMATION_TIME;
        } else {
            /* If we get a leaf to non-leaf transition, we *must* update
             * the routing table. */
            if (v->uv_flags & VIFF_LEAF && send_tables == 0)
                send_tables = addr;
            v->uv_flags &= ~VIFF_LEAF;
            v->uv_leaf_timer = 0;
        }
    }
    if (do_reset) {
        reset_neighbor_state(vifi, addr);
        if (!send_tables)
            send_tables = addr;
    }
    if (send_tables)
        report(ALL_ROUTES, vifi, send_tables);

    return (TRUE);
}


/*
 * On every timer interrupt, advance the timer in each neighbor and
 * group entry on every vif.
 */
void
age_vifs(void)
{
    vifi_t vifi;
    struct uvif *v;
    struct listaddr *a, *prev_a, *n;
    u_int32_t addr;

    for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v ) {
        if (v->uv_leaf_timer && (v->uv_leaf_timer -= TIMER_INTERVAL == 0)) {
                v->uv_flags |= VIFF_LEAF;
        }

        for (prev_a = a = v->uv_neighbors; a != NULL;) {

            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;
            if (a == v->uv_neighbors) {
                v->uv_neighbors = a->al_next;
                free((char *)a);
                prev_a = a = v->uv_neighbors;
            } else {
                prev_a->al_next = a->al_next;
                free((char *)a);
                prev_a = a = prev_a->al_next;
            }

            delete_neighbor_from_routes(addr, vifi);

            if (v->uv_neighbors == NULL)
                vifs_with_neighbors--;

            v->uv_leaf_timer = LEAF_CONFIRMATION_TIME;

            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;
                    }
                    if (!(n->al_flags & NF_LEAF)) {
                        v->uv_leaf_timer = 0;
                    }
                }
            }
        }
    }
}

/*
 * Returns the neighbor info struct for a given neighbor
 */
struct listaddr *
neighbor_info(vifi_t vifi, u_int32_t addr)
{
    struct listaddr *u;

    for (u = uvifs[vifi].uv_neighbors; u; u = u->al_next)
        if (u->al_addr == addr)
            return u;

    return NULL;
}

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

    fprintf(fp, "vifs_with_neighbors = %d\n", vifs_with_neighbors);

    if (vifs_with_neighbors == 1)
        fprintf(fp,"[This host is a leaf]\n\n");

    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: %-18s %2u %3u  %5u  ",
                vifi,
                v->uv_name,
                inet_fmt(v->uv_lcl_addr),
                (v->uv_flags & VIFF_TUNNEL) ?
                        "tunnel":
                        "subnet",
                (v->uv_flags & VIFF_TUNNEL) ?
                        inet_fmt(v->uv_rmt_addr) :
                        inet_fmts(v->uv_subnet, v->uv_subnetmask),
                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");
        if (v->uv_flags & VIFF_LEAF)     fprintf(fp, " leaf");
        if (v->uv_flags & VIFF_IGMPV1)   fprintf(fp, " IGMPv1");
        fprintf(fp, "\n");

        if (v->uv_addrs != NULL) {
            fprintf(fp, "                alternate subnets: %s\n",
                    inet_fmts(v->uv_addrs->pa_subnet,
                    v->uv_addrs->pa_subnetmask));
            for (p = v->uv_addrs->pa_next; p; p = p->pa_next) {
                fprintf(fp, "                                   %s\n",
                        inet_fmts(p->pa_subnet, p->pa_subnetmask));
            }
        }

        if (v->uv_neighbors != NULL) {
            fprintf(fp, "                            peers: %s (%d.%d) (0x%x)\n",
                    inet_fmt(v->uv_neighbors->al_addr),
                    v->uv_neighbors->al_pv, v->uv_neighbors->al_mv,
                    v->uv_neighbors->al_flags);
            for (a = v->uv_neighbors->al_next; a != NULL; a = a->al_next) {
                fprintf(fp, "                                   %s (%d.%d) (0x%x)\n",
                        inet_fmt(a->al_addr), a->al_pv,
                        a->al_mv, a->al_flags);
            }
        }

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

            fprintf(fp, "                       boundaries: %-18s\n",
                    inet_fmts(v->uv_acl->acl_addr, v->uv_acl->acl_mask));
            for (acl = v->uv_acl->acl_next; acl != NULL; acl = acl->acl_next) {
                fprintf(fp, "                                 : %-18s\n",
                        inet_fmts(acl->acl_addr, acl->acl_mask));
            }
        }
        v_req.vifi = vifi;
        if (ioctl(igmp_socket, SIOCGETVIFCNT, (char *)&v_req) < 0) {
            logit(LOG_WARNING, 0,
                "SIOCGETVIFCNT fails");
        }
        else {
            fprintf(fp, "                         pkts in : %ld\n",
                    v_req.icount);
            fprintf(fp, "                         pkts out: %ld\n",
                    v_req.ocount);
        }
        fprintf(fp, "\n");
    }
    fprintf(fp, "\n");
}

/*
 * Time out record of a group membership on a vif
 */
static void
DelVif(void *arg)
{
    cbk_t *cbk = (cbk_t *)arg;
    vifi_t vifi = cbk->vifi;
    struct uvif *v = &uvifs[vifi];
    struct listaddr *a, **anp, *g = cbk->g;

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

    delete_lclgrp(vifi, g->al_addr);

    anp = &(v->uv_groups);
    while ((a = *anp) != NULL) {
        if (a == g) {
            *anp = a->al_next;
            free((char *)a);
        } else {
            anp = &a->al_next;
        }
    }

    free(cbk);
}

/*
 * Set a timer to delete the record of a group membership on a vif.
 */
static int
SetTimer(vifi_t vifi, struct listaddr *g)
{
    cbk_t *cbk;

    cbk = (cbk_t *) malloc(sizeof(cbk_t));
    cbk->g = g;
    cbk->vifi = vifi;
    return timer_setTimer(g->al_timer, (cfunc_t)DelVif, (void *)cbk);
}

/*
 * Delete a timer that was set above.
 */
static int
DeleteTimer(int id)
{
    timer_clearTimer(id);
    return 0;
}

/*
 * Send a group-specific query.
 */
static void
SendQuery(void *arg)
{
    cbk_t *cbk = (cbk_t *)arg;
    struct uvif *v = &uvifs[cbk->vifi];

    send_igmp(v->uv_lcl_addr, cbk->g->al_addr,
              IGMP_HOST_MEMBERSHIP_QUERY,
              cbk->q_time, cbk->g->al_addr, 0);
    cbk->g->al_query = 0;
    free(cbk);
}

/*
 * Set a timer to send a group-specific query.
 */
static int
SetQueryTimer(struct listaddr *g, vifi_t vifi, int to_expire, int q_time)
{
    cbk_t *cbk;

    cbk = (cbk_t *) malloc(sizeof(cbk_t));
    cbk->g = g;
    cbk->q_time = q_time;
    cbk->vifi = vifi;
    return timer_setTimer(to_expire, (cfunc_t)SendQuery, (void *)cbk);
}