/*      $NetBSD: ip_mroute.c,v 1.166 2025/06/11 02:44:13 ozaki-r Exp $  */

/*
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Stephen Deering of Stanford University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)ip_mroute.c 8.2 (Berkeley) 11/15/93
 */

/*
 * Copyright (c) 1989 Stephen Deering
 *
 * This code is derived from software contributed to Berkeley by
 * Stephen Deering of Stanford University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)ip_mroute.c 8.2 (Berkeley) 11/15/93
 */

/*
 * IP multicast forwarding procedures
 *
 * Written by David Waitzman, BBN Labs, August 1988.
 * Modified by Steve Deering, Stanford, February 1989.
 * Modified by Mark J. Steiglitz, Stanford, May, 1991
 * Modified by Van Jacobson, LBL, January 1993
 * Modified by Ajit Thyagarajan, PARC, August 1993
 * Modified by Bill Fenner, PARC, April 1994
 * Modified by Charles M. Hannum, NetBSD, May 1995.
 * Modified by Ahmed Helmy, SGI, June 1996
 * Modified by George Edmond Eddy (Rusty), ISI, February 1998
 * Modified by Pavlin Radoslavov, USC/ISI, May 1998, August 1999, October 2000
 * Modified by Hitoshi Asaeda, WIDE, August 2000
 * Modified by Pavlin Radoslavov, ICSI, October 2002
 *
 * MROUTING Revision: 1.2
 * and PIM-SMv2 and PIM-DM support, advanced API support,
 * bandwidth metering and signaling
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ip_mroute.c,v 1.166 2025/06/11 02:44:13 ozaki-r Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#include "opt_ipsec.h"
#include "opt_pim.h"
#endif

#ifdef PIM
#define _PIM_VT 1
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/ioctl.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/raw_cb.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/in_systm.h>
#include <netinet/in_offload.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/in_pcb.h>
#include <netinet/udp.h>
#include <netinet/igmp.h>
#include <netinet/igmp_var.h>
#include <netinet/ip_mroute.h>
#ifdef PIM
#include <netinet/pim.h>
#include <netinet/pim_var.h>
#endif
#include <netinet/ip_encap.h>

#ifdef IPSEC
#include <netipsec/ipsec.h>
#include <netipsec/key.h>
#endif

#define IP_MULTICASTOPTS 0
#define M_PULLUP(m, len)                                                 \
        do {                                                             \
                if ((m) && ((m)->m_flags & M_EXT || (m)->m_len < (len))) \
                        (m) = m_pullup((m), (len));                      \
        } while (/*CONSTCOND*/ 0)

/*
 * Globals.  All but ip_mrouter and ip_mrtproto could be static,
 * except for netstat or debugging purposes.
 */
struct socket  *ip_mrouter  = NULL;
int             ip_mrtproto = IGMP_DVMRP;    /* for netstat only */

#define MFCHASH(a, g)                                                   \
        ((((a).s_addr >> 20) ^ ((a).s_addr >> 10) ^ (a).s_addr ^        \
          ((g).s_addr >> 20) ^ ((g).s_addr >> 10) ^ (g).s_addr) & mfchash)
LIST_HEAD(mfchashhdr, mfc) *mfchashtbl;
u_long  mfchash;

u_char          nexpire[MFCTBLSIZ];
struct vif      viftable[MAXVIFS];
struct mrtstat  mrtstat;
u_int           mrtdebug = 0;   /* debug level */
#define         DEBUG_MFC       0x02
#define         DEBUG_FORWARD   0x04
#define         DEBUG_EXPIRE    0x08
#define         DEBUG_XMIT      0x10
#define         DEBUG_PIM       0x20

#define         VIFI_INVALID    ((vifi_t) -1)

u_int tbfdebug = 0;     /* tbf debug level */

/* vif attachment using sys/netinet/ip_encap.c */
static void vif_input(struct mbuf *, int, int, void *);
static int vif_encapcheck(struct mbuf *, int, int, void *);

static const struct encapsw vif_encapsw = {
        .encapsw4 = {
                .pr_input       = vif_input,
                .pr_ctlinput    = NULL,
        }
};

#define         EXPIRE_TIMEOUT  (hz / 4)        /* 4x / second */
#define         UPCALL_EXPIRE   6               /* number of timeouts */

/*
 * Define the token bucket filter structures
 */

#define         TBF_REPROCESS   (hz / 100)      /* 100x / second */

static int get_sg_cnt(struct sioc_sg_req *);
static int get_vif_cnt(struct sioc_vif_req *);
static int ip_mrouter_init(struct socket *, int);
static int set_assert(int);
static int add_vif(struct vifctl *);
static int del_vif(vifi_t *);
static void update_mfc_params(struct mfc *, struct mfcctl2 *);
static void init_mfc_params(struct mfc *, struct mfcctl2 *);
static void expire_mfc(struct mfc *);
static int add_mfc(struct sockopt *);
#ifdef UPCALL_TIMING
static void collate(struct timeval *);
#endif
static int del_mfc(struct sockopt *);
static int set_api_config(struct sockopt *); /* chose API capabilities */
static int socket_send(struct socket *, struct mbuf *, struct sockaddr_in *);
static void expire_upcalls(void *);
static int ip_mdq(struct mbuf *, struct ifnet *, struct mfc *);
static void phyint_send(struct ip *, struct vif *, struct mbuf *);
static void encap_send(struct ip *, struct vif *, struct mbuf *);
static void tbf_control(struct vif *, struct mbuf *, struct ip *, u_int32_t);
static void tbf_queue(struct vif *, struct mbuf *);
static void tbf_process_q(struct vif *);
static void tbf_reprocess_q(void *);
static int tbf_dq_sel(struct vif *, struct ip *);
static void tbf_send_packet(struct vif *, struct mbuf *);
static void tbf_update_tokens(struct vif *);
static int priority(struct vif *, struct ip *);
static int ip_mforward_real(struct mbuf *, struct ifnet *);


/*
 * Bandwidth monitoring
 */
static void free_bw_list(struct bw_meter *);
static int add_bw_upcall(struct bw_upcall *);
static int del_bw_upcall(struct bw_upcall *);
static void bw_meter_receive_packet(struct bw_meter *, int , struct timeval *);
static void bw_meter_prepare_upcall(struct bw_meter *, struct timeval *);
static void bw_upcalls_send(void);
static void schedule_bw_meter(struct bw_meter *, struct timeval *);
static void unschedule_bw_meter(struct bw_meter *);
static void bw_meter_process(void);
static void expire_bw_upcalls_send(void *);
static void expire_bw_meter_process(void *);

#ifdef PIM
static int pim_register_send(struct ip *, struct vif *,
    struct mbuf *, struct mfc *);
static int pim_register_send_rp(struct ip *, struct vif *,
    struct mbuf *, struct mfc *);
static int pim_register_send_upcall(struct ip *, struct vif *,
    struct mbuf *, struct mfc *);
static struct mbuf *pim_register_prepare(struct ip *, struct mbuf *);
#endif

#define ENCAP_TTL       64
#define ENCAP_PROTO     IPPROTO_IPIP

/* prototype IP hdr for encapsulated packets */
static const struct ip multicast_encap_iphdr = {
        .ip_hl = sizeof(struct ip) >> 2,
        .ip_v = IPVERSION,
        .ip_len = sizeof(struct ip),
        .ip_ttl = ENCAP_TTL,
        .ip_p = ENCAP_PROTO,
};

/*
 * Bandwidth meter variables and constants
 */

/*
 * Pending timeouts are stored in a hash table, the key being the
 * expiration time. Periodically, the entries are analysed and processed.
 */
#define BW_METER_BUCKETS        1024
static struct bw_meter *bw_meter_timers[BW_METER_BUCKETS];
struct callout bw_meter_ch;
#define BW_METER_PERIOD (hz)            /* periodical handling of bw meters */

/*
 * Pending upcalls are stored in a vector which is flushed when
 * full, or periodically
 */
static struct bw_upcall bw_upcalls[BW_UPCALLS_MAX];
static u_int    bw_upcalls_n; /* # of pending upcalls */
struct callout  bw_upcalls_ch;
#define BW_UPCALLS_PERIOD (hz)          /* periodical flush of bw upcalls */

#ifdef PIM
struct pimstat pimstat;

/*
 * Note: the PIM Register encapsulation adds the following in front of a
 * data packet:
 *
 * struct pim_encap_hdr {
 *     struct ip ip;
 *     struct pim_encap_pimhdr  pim;
 * }
 */

struct pim_encap_pimhdr {
        struct pim pim;
        uint32_t   flags;
};

static struct ip pim_encap_iphdr = {
        .ip_v = IPVERSION,
        .ip_hl = sizeof(struct ip) >> 2,
        .ip_len = sizeof(struct ip),
        .ip_ttl = ENCAP_TTL,
        .ip_p = IPPROTO_PIM,
};

static struct pim_encap_pimhdr pim_encap_pimhdr = {
    {
        PIM_MAKE_VT(PIM_VERSION, PIM_REGISTER), /* PIM vers and message type */
        0,                      /* reserved */
        0,                      /* checksum */
    },
    0                           /* flags */
};

static struct ifnet multicast_register_if;
static vifi_t reg_vif_num = VIFI_INVALID;
#endif /* PIM */


/*
 * Private variables.
 */
static vifi_t      numvifs = 0;

static struct callout expire_upcalls_ch;

/*
 * whether or not special PIM assert processing is enabled.
 */
static int pim_assert;
/*
 * Rate limit for assert notification messages, in usec
 */
#define ASSERT_MSG_TIME         3000000

/*
 * Kernel multicast routing API capabilities and setup.
 * If more API capabilities are added to the kernel, they should be
 * recorded in `mrt_api_support'.
 */
static const u_int32_t mrt_api_support = (MRT_MFC_FLAGS_DISABLE_WRONGVIF |
                                          MRT_MFC_FLAGS_BORDER_VIF |
                                          MRT_MFC_RP |
                                          MRT_MFC_BW_UPCALL);
static u_int32_t mrt_api_config = 0;

/*
 * Find a route for a given origin IP address and Multicast group address
 * Type of service parameter to be added in the future!!!
 * Statistics are updated by the caller if needed
 * (mrtstat.mrts_mfc_lookups and mrtstat.mrts_mfc_misses)
 */
static struct mfc *
mfc_find(struct in_addr *o, struct in_addr *g)
{
        struct mfc *rt;

        LIST_FOREACH(rt, &mfchashtbl[MFCHASH(*o, *g)], mfc_hash) {
                if (in_hosteq(rt->mfc_origin, *o) &&
                    in_hosteq(rt->mfc_mcastgrp, *g) &&
                    (rt->mfc_stall == NULL))
                        break;
        }

        return rt;
}

/*
 * Macros to compute elapsed time efficiently
 * Borrowed from Van Jacobson's scheduling code
 */
#define TV_DELTA(a, b, delta) do {                                      \
        int xxs;                                                        \
        delta = (a).tv_usec - (b).tv_usec;                              \
        xxs = (a).tv_sec - (b).tv_sec;                                  \
        switch (xxs) {                                                  \
        case 2:                                                         \
                delta += 1000000;                                       \
                /* fall through */                                      \
        case 1:                                                         \
                delta += 1000000;                                       \
                /* fall through */                                      \
        case 0:                                                         \
                break;                                                  \
        default:                                                        \
                delta += (1000000 * xxs);                               \
                break;                                                  \
        }                                                               \
} while (/*CONSTCOND*/ 0)

#ifdef UPCALL_TIMING
u_int32_t upcall_data[51];
#endif /* UPCALL_TIMING */

/*
 * Handle MRT setsockopt commands to modify the multicast routing tables.
 */
int
ip_mrouter_set(struct socket *so, struct sockopt *sopt)
{
        int error;
        int optval;
        struct vifctl vifc;
        vifi_t vifi;
        struct bw_upcall bwuc;

        if (sopt->sopt_name != MRT_INIT && so != ip_mrouter)
                error = ENOPROTOOPT;
        else {
                switch (sopt->sopt_name) {
                case MRT_INIT:
                        error = sockopt_getint(sopt, &optval);
                        if (error)
                                break;

                        error = ip_mrouter_init(so, optval);
                        break;
                case MRT_DONE:
                        error = ip_mrouter_done();
                        break;
                case MRT_ADD_VIF:
                        error = sockopt_get(sopt, &vifc, sizeof(vifc));
                        if (error)
                                break;
                        error = add_vif(&vifc);
                        break;
                case MRT_DEL_VIF:
                        error = sockopt_get(sopt, &vifi, sizeof(vifi));
                        if (error)
                                break;
                        error = del_vif(&vifi);
                        break;
                case MRT_ADD_MFC:
                        error = add_mfc(sopt);
                        break;
                case MRT_DEL_MFC:
                        error = del_mfc(sopt);
                        break;
                case MRT_ASSERT:
                        error = sockopt_getint(sopt, &optval);
                        if (error)
                                break;
                        error = set_assert(optval);
                        break;
                case MRT_API_CONFIG:
                        error = set_api_config(sopt);
                        break;
                case MRT_ADD_BW_UPCALL:
                        error = sockopt_get(sopt, &bwuc, sizeof(bwuc));
                        if (error)
                                break;
                        error = add_bw_upcall(&bwuc);
                        break;
                case MRT_DEL_BW_UPCALL:
                        error = sockopt_get(sopt, &bwuc, sizeof(bwuc));
                        if (error)
                                break;
                        error = del_bw_upcall(&bwuc);
                        break;
                default:
                        error = ENOPROTOOPT;
                        break;
                }
        }
        return error;
}

/*
 * Handle MRT getsockopt commands
 */
int
ip_mrouter_get(struct socket *so, struct sockopt *sopt)
{
        int error;

        if (so != ip_mrouter)
                error = ENOPROTOOPT;
        else {
                switch (sopt->sopt_name) {
                case MRT_VERSION:
                        error = sockopt_setint(sopt, 0x0305); /* XXX !!!! */
                        break;
                case MRT_ASSERT:
                        error = sockopt_setint(sopt, pim_assert);
                        break;
                case MRT_API_SUPPORT:
                        error = sockopt_set(sopt, &mrt_api_support,
                            sizeof(mrt_api_support));
                        break;
                case MRT_API_CONFIG:
                        error = sockopt_set(sopt, &mrt_api_config,
                            sizeof(mrt_api_config));
                        break;
                default:
                        error = ENOPROTOOPT;
                        break;
                }
        }
        return error;
}

/*
 * Handle ioctl commands to obtain information from the cache
 */
int
mrt_ioctl(struct socket *so, u_long cmd, void *data)
{
        int error;

        if (so != ip_mrouter)
                error = EINVAL;
        else
                switch (cmd) {
                case SIOCGETVIFCNT:
                        error = get_vif_cnt((struct sioc_vif_req *)data);
                        break;
                case SIOCGETSGCNT:
                        error = get_sg_cnt((struct sioc_sg_req *)data);
                        break;
                default:
                        error = EINVAL;
                        break;
                }

        return error;
}

/*
 * returns the packet, byte, rpf-failure count for the source group provided
 */
static int
get_sg_cnt(struct sioc_sg_req *req)
{
        int s;
        struct mfc *rt;

        s = splsoftnet();
        rt = mfc_find(&req->src, &req->grp);
        if (rt == NULL) {
                splx(s);
                req->pktcnt = req->bytecnt = req->wrong_if = 0xffffffff;
                return EADDRNOTAVAIL;
        }
        req->pktcnt = rt->mfc_pkt_cnt;
        req->bytecnt = rt->mfc_byte_cnt;
        req->wrong_if = rt->mfc_wrong_if;
        splx(s);

        return 0;
}

/*
 * returns the input and output packet and byte counts on the vif provided
 */
static int
get_vif_cnt(struct sioc_vif_req *req)
{
        vifi_t vifi = req->vifi;

        if (vifi >= numvifs)
                return EINVAL;

        req->icount = viftable[vifi].v_pkt_in;
        req->ocount = viftable[vifi].v_pkt_out;
        req->ibytes = viftable[vifi].v_bytes_in;
        req->obytes = viftable[vifi].v_bytes_out;

        return 0;
}

/*
 * Enable multicast routing
 */
static int
ip_mrouter_init(struct socket *so, int v)
{
        if (mrtdebug)
                log(LOG_DEBUG,
                    "ip_mrouter_init: so_type = %d, pr_protocol = %d\n",
                    so->so_type, so->so_proto->pr_protocol);

        if (so->so_type != SOCK_RAW ||
            so->so_proto->pr_protocol != IPPROTO_IGMP)
                return EOPNOTSUPP;

        if (v != 1)
                return EINVAL;

        if (ip_mrouter != NULL)
                return EADDRINUSE;

        ip_mrouter = so;

        mfchashtbl = hashinit(MFCTBLSIZ, HASH_LIST, true, &mfchash);
        memset((void *)nexpire, 0, sizeof(nexpire));

        pim_assert = 0;

        callout_init(&expire_upcalls_ch, 0);
        callout_reset(&expire_upcalls_ch, EXPIRE_TIMEOUT,
                      expire_upcalls, NULL);

        callout_init(&bw_upcalls_ch, 0);
        callout_reset(&bw_upcalls_ch, BW_UPCALLS_PERIOD,
                      expire_bw_upcalls_send, NULL);

        callout_init(&bw_meter_ch, 0);
        callout_reset(&bw_meter_ch, BW_METER_PERIOD,
                      expire_bw_meter_process, NULL);

        if (mrtdebug)
                log(LOG_DEBUG, "ip_mrouter_init\n");

        return 0;
}

/*
 * Disable multicast routing
 */
int
ip_mrouter_done(void)
{
        vifi_t vifi;
        struct vif *vifp;
        int i;
        int s;

        s = splsoftnet();

        /* Clear out all the vifs currently in use. */
        for (vifi = 0; vifi < numvifs; vifi++) {
                vifp = &viftable[vifi];
                if (!in_nullhost(vifp->v_lcl_addr))
                        reset_vif(vifp);
        }

        numvifs = 0;
        pim_assert = 0;
        mrt_api_config = 0;

        callout_stop(&expire_upcalls_ch);
        callout_stop(&bw_upcalls_ch);
        callout_stop(&bw_meter_ch);

        /*
         * Free all multicast forwarding cache entries.
         */
        for (i = 0; i < MFCTBLSIZ; i++) {
                struct mfc *rt, *nrt;

                for (rt = LIST_FIRST(&mfchashtbl[i]); rt; rt = nrt) {
                        nrt = LIST_NEXT(rt, mfc_hash);

                        expire_mfc(rt);
                }
        }

        memset((void *)nexpire, 0, sizeof(nexpire));
        hashdone(mfchashtbl, HASH_LIST, mfchash);
        mfchashtbl = NULL;

        bw_upcalls_n = 0;
        memset(bw_meter_timers, 0, sizeof(bw_meter_timers));

        /* Reset de-encapsulation cache. */

        ip_mrouter = NULL;

        splx(s);

        if (mrtdebug)
                log(LOG_DEBUG, "ip_mrouter_done\n");

        return 0;
}

void
ip_mrouter_detach(struct ifnet *ifp)
{
        int vifi, i;
        struct vif *vifp;
        struct mfc *rt;
        struct rtdetq *rte;

        /* XXX not sure about side effect to userland routing daemon */
        for (vifi = 0; vifi < numvifs; vifi++) {
                vifp = &viftable[vifi];
                if (vifp->v_ifp == ifp)
                        reset_vif(vifp);
        }
        for (i = 0; i < MFCTBLSIZ; i++) {
                if (nexpire[i] == 0)
                        continue;
                LIST_FOREACH(rt, &mfchashtbl[i], mfc_hash) {
                        for (rte = rt->mfc_stall; rte; rte = rte->next) {
                                if (rte->ifp == ifp)
                                        rte->ifp = NULL;
                        }
                }
        }
}

/*
 * Set PIM assert processing global
 */
static int
set_assert(int i)
{
        pim_assert = !!i;
        return 0;
}

/*
 * Configure API capabilities
 */
static int
set_api_config(struct sockopt *sopt)
{
        u_int32_t apival;
        int i, error;

        /*
         * We can set the API capabilities only if it is the first operation
         * after MRT_INIT. I.e.:
         *  - there are no vifs installed
         *  - pim_assert is not enabled
         *  - the MFC table is empty
         */
        error = sockopt_get(sopt, &apival, sizeof(apival));
        if (error)
                return error;
        if (numvifs > 0)
                return EPERM;
        if (pim_assert)
                return EPERM;
        for (i = 0; i < MFCTBLSIZ; i++) {
                if (LIST_FIRST(&mfchashtbl[i]) != NULL)
                        return EPERM;
        }

        mrt_api_config = apival & mrt_api_support;
        return 0;
}

/*
 * Add a vif to the vif table
 */
static int
add_vif(struct vifctl *vifcp)
{
        struct vif *vifp;
        struct ifnet *ifp;
        int error, s;
        struct sockaddr_in sin;

        if (vifcp->vifc_vifi >= MAXVIFS)
                return EINVAL;
        if (in_nullhost(vifcp->vifc_lcl_addr))
                return EADDRNOTAVAIL;

        vifp = &viftable[vifcp->vifc_vifi];
        if (!in_nullhost(vifp->v_lcl_addr))
                return EADDRINUSE;

        /* Find the interface with an address in AF_INET family. */
#ifdef PIM
        if (vifcp->vifc_flags & VIFF_REGISTER) {
                /*
                 * XXX: Because VIFF_REGISTER does not really need a valid
                 * local interface (e.g. it could be 127.0.0.2), we don't
                 * check its address.
                 */
                ifp = NULL;
        } else
#endif
        {
                struct ifaddr *ifa;

                sockaddr_in_init(&sin, &vifcp->vifc_lcl_addr, 0);
                s = pserialize_read_enter();
                ifa = ifa_ifwithaddr(sintosa(&sin));
                if (ifa == NULL) {
                        pserialize_read_exit(s);
                        return EADDRNOTAVAIL;
                }
                ifp = ifa->ifa_ifp;
                /* FIXME NOMPSAFE */
                pserialize_read_exit(s);
        }

        if (vifcp->vifc_flags & VIFF_TUNNEL) {
                if (vifcp->vifc_flags & VIFF_SRCRT) {
                        log(LOG_ERR, "source routed tunnels not supported\n");
                        return EOPNOTSUPP;
                }

                /* attach this vif to decapsulator dispatch table */
                /*
                 * XXX Use addresses in registration so that matching
                 * can be done with radix tree in decapsulator.  But,
                 * we need to check inner header for multicast, so
                 * this requires both radix tree lookup and then a
                 * function to check, and this is not supported yet.
                 */
                error = encap_lock_enter();
                if (error)
                        return error;
                vifp->v_encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV4,
                    vif_encapcheck, &vif_encapsw, vifp);
                encap_lock_exit();
                if (!vifp->v_encap_cookie)
                        return EINVAL;

                /* Create a fake encapsulation interface. */
                ifp = malloc(sizeof(*ifp), M_MRTABLE, M_WAITOK|M_ZERO);
                snprintf(ifp->if_xname, sizeof(ifp->if_xname),
                         "mdecap%d", vifcp->vifc_vifi);

                /* Prepare cached route entry. */
                memset(&vifp->v_route, 0, sizeof(vifp->v_route));
#ifdef PIM
        } else if (vifcp->vifc_flags & VIFF_REGISTER) {
                ifp = &multicast_register_if;
                if (mrtdebug)
                        log(LOG_DEBUG, "Adding a register vif, ifp: %p\n",
                            (void *)ifp);
                if (reg_vif_num == VIFI_INVALID) {
                        memset(ifp, 0, sizeof(*ifp));
                        snprintf(ifp->if_xname, sizeof(ifp->if_xname),
                                 "register_vif");
                        ifp->if_flags = IFF_LOOPBACK;
                        memset(&vifp->v_route, 0, sizeof(vifp->v_route));
                        reg_vif_num = vifcp->vifc_vifi;
                }
#endif
        } else {
                /* Make sure the interface supports multicast. */
                if ((ifp->if_flags & IFF_MULTICAST) == 0)
                        return EOPNOTSUPP;

                /* Enable promiscuous reception of all IP multicasts. */
                sockaddr_in_init(&sin, &zeroin_addr, 0);
                error = if_mcast_op(ifp, SIOCADDMULTI, sintosa(&sin));
                if (error)
                        return error;
        }

        s = splsoftnet();

        /* Define parameters for the tbf structure. */
        vifp->tbf_q = NULL;
        vifp->tbf_t = &vifp->tbf_q;
        microtime(&vifp->tbf_last_pkt_t);
        vifp->tbf_n_tok = 0;
        vifp->tbf_q_len = 0;
        vifp->tbf_max_q_len = MAXQSIZE;

        vifp->v_flags = vifcp->vifc_flags;
        vifp->v_threshold = vifcp->vifc_threshold;
        /* scaling up here allows division by 1024 in critical code */
        vifp->v_rate_limit = vifcp->vifc_rate_limit * 1024 / 1000;
        vifp->v_lcl_addr = vifcp->vifc_lcl_addr;
        vifp->v_rmt_addr = vifcp->vifc_rmt_addr;
        vifp->v_ifp = ifp;
        /* Initialize per vif pkt counters. */
        vifp->v_pkt_in = 0;
        vifp->v_pkt_out = 0;
        vifp->v_bytes_in = 0;
        vifp->v_bytes_out = 0;

        callout_init(&vifp->v_repq_ch, 0);

        splx(s);

        /* Adjust numvifs up if the vifi is higher than numvifs. */
        if (numvifs <= vifcp->vifc_vifi)
                numvifs = vifcp->vifc_vifi + 1;

        if (mrtdebug)
                log(LOG_DEBUG, "add_vif #%d, lcladdr %x, %s %x, thresh %x, rate %d\n",
                    vifcp->vifc_vifi,
                    ntohl(vifcp->vifc_lcl_addr.s_addr),
                    (vifcp->vifc_flags & VIFF_TUNNEL) ? "rmtaddr" : "mask",
                    ntohl(vifcp->vifc_rmt_addr.s_addr),
                    vifcp->vifc_threshold,
                    vifcp->vifc_rate_limit);

        return 0;
}

void
reset_vif(struct vif *vifp)
{
        struct mbuf *m, *n;
        struct ifnet *ifp;
        struct sockaddr_in sin;

        callout_stop(&vifp->v_repq_ch);

        /* detach this vif from decapsulator dispatch table */
        encap_lock_enter();
        encap_detach(vifp->v_encap_cookie);
        encap_lock_exit();
        vifp->v_encap_cookie = NULL;

        /*
         * Free packets queued at the interface
         */
        for (m = vifp->tbf_q; m != NULL; m = n) {
                n = m->m_nextpkt;
                m_freem(m);
        }

        if (vifp->v_flags & VIFF_TUNNEL)
                free(vifp->v_ifp, M_MRTABLE);
        else if (vifp->v_flags & VIFF_REGISTER) {
#ifdef PIM
                reg_vif_num = VIFI_INVALID;
#endif
        } else {
                sockaddr_in_init(&sin, &zeroin_addr, 0);
                ifp = vifp->v_ifp;
                if_mcast_op(ifp, SIOCDELMULTI, sintosa(&sin));
        }
        memset((void *)vifp, 0, sizeof(*vifp));
}

/*
 * Delete a vif from the vif table
 */
static int
del_vif(vifi_t *vifip)
{
        struct vif *vifp;
        vifi_t vifi;
        int s;

        if (*vifip >= numvifs)
                return EINVAL;

        vifp = &viftable[*vifip];
        if (in_nullhost(vifp->v_lcl_addr))
                return EADDRNOTAVAIL;

        s = splsoftnet();

        reset_vif(vifp);

        /* Adjust numvifs down */
        for (vifi = numvifs; vifi > 0; vifi--)
                if (!in_nullhost(viftable[vifi - 1].v_lcl_addr))
                        break;
        numvifs = vifi;

        splx(s);

        if (mrtdebug)
                log(LOG_DEBUG, "del_vif %d, numvifs %d\n", *vifip, numvifs);

        return 0;
}

/*
 * update an mfc entry without resetting counters and S,G addresses.
 */
static void
update_mfc_params(struct mfc *rt, struct mfcctl2 *mfccp)
{
        int i;

        rt->mfc_parent = mfccp->mfcc_parent;
        for (i = 0; i < numvifs; i++) {
                rt->mfc_ttls[i] = mfccp->mfcc_ttls[i];
                rt->mfc_flags[i] = mfccp->mfcc_flags[i] & mrt_api_config &
                        MRT_MFC_FLAGS_ALL;
        }
        /* set the RP address */
        if (mrt_api_config & MRT_MFC_RP)
                rt->mfc_rp = mfccp->mfcc_rp;
        else
                rt->mfc_rp = zeroin_addr;
}

/*
 * fully initialize an mfc entry from the parameter.
 */
static void
init_mfc_params(struct mfc *rt, struct mfcctl2 *mfccp)
{
        rt->mfc_origin     = mfccp->mfcc_origin;
        rt->mfc_mcastgrp   = mfccp->mfcc_mcastgrp;

        update_mfc_params(rt, mfccp);

        /* initialize pkt counters per src-grp */
        rt->mfc_pkt_cnt    = 0;
        rt->mfc_byte_cnt   = 0;
        rt->mfc_wrong_if   = 0;
        timerclear(&rt->mfc_last_assert);
}

static void
expire_mfc(struct mfc *rt)
{
        struct rtdetq *rte, *nrte;

        free_bw_list(rt->mfc_bw_meter);

        for (rte = rt->mfc_stall; rte != NULL; rte = nrte) {
                nrte = rte->next;
                m_freem(rte->m);
                free(rte, M_MRTABLE);
        }

        LIST_REMOVE(rt, mfc_hash);
        free(rt, M_MRTABLE);
}

/*
 * Add an mfc entry
 */
static int
add_mfc(struct sockopt *sopt)
{
        struct mfcctl2 mfcctl2;
        struct mfcctl2 *mfccp;
        struct mfc *rt;
        u_int32_t hash = 0;
        struct rtdetq *rte, *nrte;
        u_short nstl;
        int s;
        int error;

        /*
         * select data size depending on API version.
         */
        mfccp = &mfcctl2;
        memset(&mfcctl2, 0, sizeof(mfcctl2));

        if (mrt_api_config & MRT_API_FLAGS_ALL)
                error = sockopt_get(sopt, mfccp, sizeof(struct mfcctl2));
        else
                error = sockopt_get(sopt, mfccp, sizeof(struct mfcctl));

        if (error)
                return error;

        s = splsoftnet();
        rt = mfc_find(&mfccp->mfcc_origin, &mfccp->mfcc_mcastgrp);

        /* If an entry already exists, just update the fields */
        if (rt) {
                if (mrtdebug & DEBUG_MFC)
                        log(LOG_DEBUG, "add_mfc update o %x g %x p %x\n",
                            ntohl(mfccp->mfcc_origin.s_addr),
                            ntohl(mfccp->mfcc_mcastgrp.s_addr),
                            mfccp->mfcc_parent);

                update_mfc_params(rt, mfccp);

                splx(s);
                return 0;
        }

        /*
         * Find the entry for which the upcall was made and update
         */
        nstl = 0;
        hash = MFCHASH(mfccp->mfcc_origin, mfccp->mfcc_mcastgrp);
        LIST_FOREACH(rt, &mfchashtbl[hash], mfc_hash) {
                if (in_hosteq(rt->mfc_origin, mfccp->mfcc_origin) &&
                    in_hosteq(rt->mfc_mcastgrp, mfccp->mfcc_mcastgrp) &&
                    rt->mfc_stall != NULL) {
                        if (nstl++)
                                log(LOG_ERR, "add_mfc %s o %x g %x p %x dbx %p\n",
                                    "multiple kernel entries",
                                    ntohl(mfccp->mfcc_origin.s_addr),
                                    ntohl(mfccp->mfcc_mcastgrp.s_addr),
                                    mfccp->mfcc_parent, rt->mfc_stall);

                        if (mrtdebug & DEBUG_MFC)
                                log(LOG_DEBUG, "add_mfc o %x g %x p %x dbg %p\n",
                                    ntohl(mfccp->mfcc_origin.s_addr),
                                    ntohl(mfccp->mfcc_mcastgrp.s_addr),
                                    mfccp->mfcc_parent, rt->mfc_stall);

                        rte = rt->mfc_stall;
                        init_mfc_params(rt, mfccp);
                        rt->mfc_stall = NULL;

                        rt->mfc_expire = 0; /* Don't clean this guy up */
                        nexpire[hash]--;

                        /* free packets Qed at the end of this entry */
                        for (; rte != NULL; rte = nrte) {
                                nrte = rte->next;
                                if (rte->ifp) {
                                        ip_mdq(rte->m, rte->ifp, rt);
                                }
                                m_freem(rte->m);
#ifdef UPCALL_TIMING
                                collate(&rte->t);
#endif /* UPCALL_TIMING */
                                free(rte, M_MRTABLE);
                        }
                }
        }

        /*
         * It is possible that an entry is being inserted without an upcall
         */
        if (nstl == 0) {
                /*
                 * No mfc; make a new one
                 */
                if (mrtdebug & DEBUG_MFC)
                        log(LOG_DEBUG, "add_mfc no upcall o %x g %x p %x\n",
                            ntohl(mfccp->mfcc_origin.s_addr),
                            ntohl(mfccp->mfcc_mcastgrp.s_addr),
                            mfccp->mfcc_parent);

                LIST_FOREACH(rt, &mfchashtbl[hash], mfc_hash) {
                        if (in_hosteq(rt->mfc_origin, mfccp->mfcc_origin) &&
                            in_hosteq(rt->mfc_mcastgrp, mfccp->mfcc_mcastgrp)) {
                                init_mfc_params(rt, mfccp);
                                if (rt->mfc_expire)
                                        nexpire[hash]--;
                                rt->mfc_expire = 0;
                                break; /* XXX */
                        }
                }
                if (rt == NULL) {       /* no upcall, so make a new entry */
                        rt = malloc(sizeof(*rt), M_MRTABLE, M_NOWAIT);
                        if (rt == NULL) {
                                splx(s);
                                return ENOBUFS;
                        }

                        init_mfc_params(rt, mfccp);
                        rt->mfc_expire  = 0;
                        rt->mfc_stall   = NULL;
                        rt->mfc_bw_meter = NULL;

                        /* insert new entry at head of hash chain */
                        LIST_INSERT_HEAD(&mfchashtbl[hash], rt, mfc_hash);
                }
        }

        splx(s);
        return 0;
}

#ifdef UPCALL_TIMING
/*
 * collect delay statistics on the upcalls
 */
static void
collate(struct timeval *t)
{
        u_int32_t d;
        struct timeval tp;
        u_int32_t delta;

        microtime(&tp);

        if (timercmp(t, &tp, <)) {
                TV_DELTA(tp, *t, delta);

                d = delta >> 10;
                if (d > 50)
                        d = 50;

                ++upcall_data[d];
        }
}
#endif /* UPCALL_TIMING */

/*
 * Delete an mfc entry
 */
static int
del_mfc(struct sockopt *sopt)
{
        struct mfcctl2 mfcctl2;
        struct mfcctl2 *mfccp;
        struct mfc *rt;
        int s;
        int error;

        /*
         * XXX: for deleting MFC entries the information in entries
         * of size "struct mfcctl" is sufficient.
         */

        mfccp = &mfcctl2;
        memset(&mfcctl2, 0, sizeof(mfcctl2));

        error = sockopt_get(sopt, mfccp, sizeof(struct mfcctl));
        if (error) {
                /* Try with the size of mfcctl2. */
                error = sockopt_get(sopt, mfccp, sizeof(struct mfcctl2));
                if (error)
                        return error;
        }

        if (mrtdebug & DEBUG_MFC)
                log(LOG_DEBUG, "del_mfc origin %x mcastgrp %x\n",
                    ntohl(mfccp->mfcc_origin.s_addr),
                    ntohl(mfccp->mfcc_mcastgrp.s_addr));

        s = splsoftnet();

        rt = mfc_find(&mfccp->mfcc_origin, &mfccp->mfcc_mcastgrp);
        if (rt == NULL) {
                splx(s);
                return EADDRNOTAVAIL;
        }

        /*
         * free the bw_meter entries
         */
        free_bw_list(rt->mfc_bw_meter);
        rt->mfc_bw_meter = NULL;

        LIST_REMOVE(rt, mfc_hash);
        free(rt, M_MRTABLE);

        splx(s);
        return 0;
}

static int
socket_send(struct socket *s, struct mbuf *mm, struct sockaddr_in *src)
{
        if (s) {
                if (sbappendaddr(&s->so_rcv, sintosa(src), mm, NULL) != 0) {
                        sorwakeup(s);
                        return 0;
                }
                soroverflow(s);
        }
        m_freem(mm);
        return -1;
}

/*
 * IP multicast forwarding function. This function assumes that the packet
 * pointed to by "ip" has arrived on (or is about to be sent to) the interface
 * pointed to by "ifp", and the packet is to be relayed to other networks
 * that have members of the packet's destination IP multicast group.
 *
 * The packet is returned unscathed to the caller, unless it is
 * erroneous, in which case a non-zero return value tells the caller to
 * discard it.
 */

#define IP_HDR_LEN  20  /* # bytes of fixed IP header (excluding options) */
#define TUNNEL_LEN  12  /* # bytes of IP option for tunnel encapsulation  */

int
ip_mforward(struct mbuf *m, struct ifnet *ifp)
{
        int rc;
        /*
         * save csum_flags to uphold the 
         * "unscathed" guarantee.
         * ip_output() relies on that and
         * without it we send out
         * multicast packets with an invalid
         * checksum
         *
         * see PR kern/55779
         */
        int csum_flags = m->m_pkthdr.csum_flags;

        /*
         * Temporarily clear any in-bound checksum flags for this packet.
         */
        m->m_pkthdr.csum_flags = 0;

        rc = ip_mforward_real(m, ifp);

        m->m_pkthdr.csum_flags = csum_flags;

        return rc;
}

static int
ip_mforward_real(struct mbuf *m, struct ifnet *ifp)
{
        struct ip *ip = mtod(m, struct ip *);
        struct mfc *rt;
        static int srctun = 0;
        struct mbuf *mm;
        struct sockaddr_in sin;
        int s;
        vifi_t vifi;

        if (mrtdebug & DEBUG_FORWARD)
                log(LOG_DEBUG, "ip_mforward: src %x, dst %x, ifp %p\n",
                    ntohl(ip->ip_src.s_addr), ntohl(ip->ip_dst.s_addr), ifp);

        /*
         * XXX XXX: Why do we check [1] against IPOPT_LSRR? Because we
         * expect [0] to be IPOPT_NOP, maybe? In all cases that doesn't
         * make a lot of sense, a forged packet can just put two IPOPT_NOPs
         * followed by one IPOPT_LSRR, and bypass the check.
         */
        if (ip->ip_hl < (IP_HDR_LEN + TUNNEL_LEN) >> 2 ||
            ((u_char *)(ip + 1))[1] != IPOPT_LSRR) {
                /*
                 * Packet arrived via a physical interface or
                 * an encapsulated tunnel or a register_vif.
                 */
        } else {
                /*
                 * Packet arrived through a source-route tunnel.
                 * Source-route tunnels are no longer supported.
                 */
                if ((srctun++ % 1000) == 0)
                        log(LOG_ERR,
                            "ip_mforward: received source-routed packet from %x\n",
                            ntohl(ip->ip_src.s_addr));
                return EOPNOTSUPP;
        }

        /*
         * Don't forward a packet with time-to-live of zero or one,
         * or a packet destined to a local-only group.
         */
        if (ip->ip_ttl <= 1 || IN_LOCAL_GROUP(ip->ip_dst.s_addr))
                return 0;

        /*
         * Determine forwarding vifs from the forwarding cache table
         */
        s = splsoftnet();
        ++mrtstat.mrts_mfc_lookups;
        rt = mfc_find(&ip->ip_src, &ip->ip_dst);

        /* Entry exists, so forward if necessary */
        if (rt != NULL) {
                splx(s);
                return ip_mdq(m, ifp, rt);
        } else {
                /*
                 * If we don't have a route for packet's origin, make a copy
                 * of the packet and send message to routing daemon.
                 */

                struct mbuf *mb0;
                struct rtdetq *rte;
                u_int32_t hash;
                const int hlen = ip->ip_hl << 2;
#ifdef UPCALL_TIMING
                struct timeval tp;
                microtime(&tp);
#endif

                ++mrtstat.mrts_mfc_misses;

                mrtstat.mrts_no_route++;
                if (mrtdebug & (DEBUG_FORWARD | DEBUG_MFC))
                        log(LOG_DEBUG, "ip_mforward: no rte s %x g %x\n",
                            ntohl(ip->ip_src.s_addr),
                            ntohl(ip->ip_dst.s_addr));

                /*
                 * Allocate mbufs early so that we don't do extra work if we are
                 * just going to fail anyway.  Make sure to pullup the header so
                 * that other people can't step on it.
                 */
                rte = malloc(sizeof(*rte), M_MRTABLE, M_NOWAIT);
                if (rte == NULL) {
                        splx(s);
                        return ENOBUFS;
                }
                mb0 = m_copypacket(m, M_DONTWAIT);
                M_PULLUP(mb0, hlen);
                if (mb0 == NULL) {
                        free(rte, M_MRTABLE);
                        splx(s);
                        return ENOBUFS;
                }

                /* is there an upcall waiting for this flow? */
                hash = MFCHASH(ip->ip_src, ip->ip_dst);
                LIST_FOREACH(rt, &mfchashtbl[hash], mfc_hash) {
                        if (in_hosteq(ip->ip_src, rt->mfc_origin) &&
                            in_hosteq(ip->ip_dst, rt->mfc_mcastgrp) &&
                            rt->mfc_stall != NULL)
                                break;
                }

                if (rt == NULL) {
                        int i;
                        struct igmpmsg *im;

                        /*
                         * Locate the vifi for the incoming interface for
                         * this packet.
                         * If none found, drop packet.
                         */
                        for (vifi = 0; vifi < numvifs &&
                                 viftable[vifi].v_ifp != ifp; vifi++)
                                ;
                        if (vifi >= numvifs) /* vif not found, drop packet */
                                goto non_fatal;

                        /* no upcall, so make a new entry */
                        rt = malloc(sizeof(*rt), M_MRTABLE, M_NOWAIT);
                        if (rt == NULL)
                                goto fail;

                        /*
                         * Make a copy of the header to send to the user level
                         * process
                         */
                        mm = m_copym(m, 0, hlen, M_DONTWAIT);
                        M_PULLUP(mm, hlen);
                        if (mm == NULL)
                                goto fail1;

                        /*
                         * Send message to routing daemon to install
                         * a route into the kernel table
                         */

                        im = mtod(mm, struct igmpmsg *);
                        im->im_msgtype = IGMPMSG_NOCACHE;
                        im->im_mbz = 0;
                        im->im_vif = vifi;

                        mrtstat.mrts_upcalls++;

                        sockaddr_in_init(&sin, &ip->ip_src, 0);
                        if (socket_send(ip_mrouter, mm, &sin) < 0) {
                                log(LOG_WARNING,
                                    "ip_mforward: ip_mrouter socket queue full\n");
                                ++mrtstat.mrts_upq_sockfull;
                        fail1:
                                free(rt, M_MRTABLE);
                        fail:
                                free(rte, M_MRTABLE);
                                m_freem(mb0);
                                splx(s);
                                return ENOBUFS;
                        }

                        /* insert new entry at head of hash chain */
                        rt->mfc_origin = ip->ip_src;
                        rt->mfc_mcastgrp = ip->ip_dst;
                        rt->mfc_pkt_cnt = 0;
                        rt->mfc_byte_cnt = 0;
                        rt->mfc_wrong_if = 0;
                        rt->mfc_expire = UPCALL_EXPIRE;
                        nexpire[hash]++;
                        for (i = 0; i < numvifs; i++) {
                                rt->mfc_ttls[i] = 0;
                                rt->mfc_flags[i] = 0;
                        }
                        rt->mfc_parent = -1;

                        /* clear the RP address */
                        rt->mfc_rp = zeroin_addr;

                        rt->mfc_bw_meter = NULL;

                        /* link into table */
                        LIST_INSERT_HEAD(&mfchashtbl[hash], rt, mfc_hash);
                        /* Add this entry to the end of the queue */
                        rt->mfc_stall = rte;
                } else {
                        /* determine if q has overflowed */
                        struct rtdetq **p;
                        int npkts = 0;

                        /*
                         * XXX ouch! we need to append to the list, but we
                         * only have a pointer to the front, so we have to
                         * scan the entire list every time.
                         */
                        for (p = &rt->mfc_stall; *p != NULL; p = &(*p)->next)
                                if (++npkts > MAX_UPQ) {
                                        mrtstat.mrts_upq_ovflw++;
                                non_fatal:
                                        free(rte, M_MRTABLE);
                                        m_freem(mb0);
                                        splx(s);
                                        return 0;
                                }

                        /* Add this entry to the end of the queue */
                        *p = rte;
                }

                rte->next = NULL;
                rte->m = mb0;
                rte->ifp = ifp;
#ifdef UPCALL_TIMING
                rte->t = tp;
#endif

                splx(s);

                return 0;
        }
}

/*ARGSUSED*/
static void
expire_upcalls(void *v)
{
        int i;

        /* XXX NOMPSAFE still need softnet_lock */
        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);

        for (i = 0; i < MFCTBLSIZ; i++) {
                struct mfc *rt, *nrt;

                if (nexpire[i] == 0)
                        continue;

                for (rt = LIST_FIRST(&mfchashtbl[i]); rt; rt = nrt) {
                        nrt = LIST_NEXT(rt, mfc_hash);

                        if (rt->mfc_expire == 0 || --rt->mfc_expire > 0)
                                continue;
                        nexpire[i]--;

                        /*
                         * free the bw_meter entries
                         */
                        while (rt->mfc_bw_meter != NULL) {
                                struct bw_meter *x = rt->mfc_bw_meter;

                                rt->mfc_bw_meter = x->bm_mfc_next;
                                kmem_intr_free(x, sizeof(*x));
                        }

                        ++mrtstat.mrts_cache_cleanups;
                        if (mrtdebug & DEBUG_EXPIRE)
                                log(LOG_DEBUG,
                                    "expire_upcalls: expiring (%x %x)\n",
                                    ntohl(rt->mfc_origin.s_addr),
                                    ntohl(rt->mfc_mcastgrp.s_addr));

                        expire_mfc(rt);
                }
        }

        callout_reset(&expire_upcalls_ch, EXPIRE_TIMEOUT,
            expire_upcalls, NULL);

        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

/*
 * Macro to send packet on vif.
 */
#define MC_SEND(ip, vifp, m) do {                                       \
        if ((vifp)->v_flags & VIFF_TUNNEL)                              \
                encap_send((ip), (vifp), (m));                          \
        else                                                            \
                phyint_send((ip), (vifp), (m));                         \
} while (/*CONSTCOND*/ 0)

/*
 * Packet forwarding routine once entry in the cache is made
 */
static int
ip_mdq(struct mbuf *m, struct ifnet *ifp, struct mfc *rt)
{
        struct ip *ip = mtod(m, struct ip *);
        vifi_t vifi;
        struct vif *vifp;
        struct sockaddr_in sin;
        const int plen = ntohs(ip->ip_len) - (ip->ip_hl << 2);

        /*
         * Don't forward if it didn't arrive from the parent vif for its origin.
         */
        vifi = rt->mfc_parent;
        if ((vifi >= numvifs) || (viftable[vifi].v_ifp != ifp)) {
                /* came in the wrong interface */
                if (mrtdebug & DEBUG_FORWARD)
                        log(LOG_DEBUG, "wrong if: ifp %p vifi %d vififp %p\n",
                            ifp, vifi,
                            vifi >= numvifs ? 0 : viftable[vifi].v_ifp);
                ++mrtstat.mrts_wrong_if;
                ++rt->mfc_wrong_if;

                /*
                 * If we are doing PIM assert processing, send a message
                 * to the routing daemon.
                 *
                 * XXX: A PIM-SM router needs the WRONGVIF detection so it
                 * can complete the SPT switch, regardless of the type
                 * of the iif (broadcast media, GRE tunnel, etc).
                 */
                if (pim_assert && (vifi < numvifs) && viftable[vifi].v_ifp) {
                        struct timeval now;
                        u_int32_t delta;

#ifdef PIM
                        if (ifp == &multicast_register_if)
                                pimstat.pims_rcv_registers_wrongiif++;
#endif

                        /* Get vifi for the incoming packet */
                        for (vifi = 0;
                             vifi < numvifs && viftable[vifi].v_ifp != ifp;
                             vifi++)
                            ;
                        if (vifi >= numvifs) {
                                /* The iif is not found: ignore the packet. */
                                return 0;
                        }

                        if (rt->mfc_flags[vifi] &
                            MRT_MFC_FLAGS_DISABLE_WRONGVIF) {
                                /* WRONGVIF disabled: ignore the packet */
                                return 0;
                        }

                        microtime(&now);

                        TV_DELTA(rt->mfc_last_assert, now, delta);

                        if (delta > ASSERT_MSG_TIME) {
                                struct igmpmsg *im;
                                const int hlen = ip->ip_hl << 2;
                                struct mbuf *mm =
                                    m_copym(m, 0, hlen, M_DONTWAIT);

                                M_PULLUP(mm, hlen);
                                if (mm == NULL)
                                        return ENOBUFS;

                                rt->mfc_last_assert = now;

                                im = mtod(mm, struct igmpmsg *);
                                im->im_msgtype  = IGMPMSG_WRONGVIF;
                                im->im_mbz      = 0;
                                im->im_vif      = vifi;

                                mrtstat.mrts_upcalls++;

                                sockaddr_in_init(&sin, &im->im_src, 0);
                                if (socket_send(ip_mrouter, mm, &sin) < 0) {
                                        log(LOG_WARNING,
                                            "ip_mforward: ip_mrouter socket queue full\n");
                                        ++mrtstat.mrts_upq_sockfull;
                                        return ENOBUFS;
                                }
                        }
                }
                return 0;
        }

        /* If I sourced this packet, it counts as output, else it was input. */
        if (in_hosteq(ip->ip_src, viftable[vifi].v_lcl_addr)) {
                viftable[vifi].v_pkt_out++;
                viftable[vifi].v_bytes_out += plen;
        } else {
                viftable[vifi].v_pkt_in++;
                viftable[vifi].v_bytes_in += plen;
        }
        rt->mfc_pkt_cnt++;
        rt->mfc_byte_cnt += plen;

        /*
         * For each vif, decide if a copy of the packet should be forwarded.
         * Forward if:
         *  - the ttl exceeds the vif's threshold
         *  - there are group members downstream on interface
         */
        for (vifp = viftable, vifi = 0; vifi < numvifs; vifp++, vifi++) {
                if ((rt->mfc_ttls[vifi] > 0) &&
                        (ip->ip_ttl > rt->mfc_ttls[vifi])) {
                        vifp->v_pkt_out++;
                        vifp->v_bytes_out += plen;
#ifdef PIM
                        if (vifp->v_flags & VIFF_REGISTER)
                                pim_register_send(ip, vifp, m, rt);
                        else
#endif
                        MC_SEND(ip, vifp, m);
                }
        }

        /*
         * Perform upcall-related bw measuring.
         */
        if (rt->mfc_bw_meter != NULL) {
                struct bw_meter *x;
                struct timeval now;

                microtime(&now);
                for (x = rt->mfc_bw_meter; x != NULL; x = x->bm_mfc_next)
                        bw_meter_receive_packet(x, plen, &now);
        }

        return 0;
}

static void
phyint_send(struct ip *ip, struct vif *vifp, struct mbuf *m)
{
        struct mbuf *mb_copy;
        const int hlen = ip->ip_hl << 2;

        /*
         * Make a new reference to the packet; make sure that
         * the IP header is actually copied, not just referenced,
         * so that ip_output() only scribbles on the copy.
         */
        mb_copy = m_copypacket(m, M_DONTWAIT);
        M_PULLUP(mb_copy, hlen);
        if (mb_copy == NULL)
                return;

        if (vifp->v_rate_limit <= 0)
                tbf_send_packet(vifp, mb_copy);
        else
                tbf_control(vifp, mb_copy, mtod(mb_copy, struct ip *),
                    ntohs(ip->ip_len));
}

static void
encap_send(struct ip *ip, struct vif *vifp, struct mbuf *m)
{
        struct mbuf *mb_copy;
        struct ip *ip_copy;
        int i, len = ntohs(ip->ip_len) + sizeof(multicast_encap_iphdr);

        /* Take care of delayed checksums */
        if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                in_undefer_cksum_tcpudp(m);
                m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv4|M_CSUM_UDPv4);
        }

        /*
         * copy the old packet & pullup its IP header into the
         * new mbuf so we can modify it.  Try to fill the new
         * mbuf since if we don't the ethernet driver will.
         */
        MGETHDR(mb_copy, M_DONTWAIT, MT_DATA);
        if (mb_copy == NULL)
                return;
        mb_copy->m_data += max_linkhdr;
        mb_copy->m_pkthdr.len = len;
        mb_copy->m_len = sizeof(multicast_encap_iphdr);

        if ((mb_copy->m_next = m_copypacket(m, M_DONTWAIT)) == NULL) {
                m_freem(mb_copy);
                return;
        }
        i = MHLEN - max_linkhdr;
        if (i > len)
                i = len;
        mb_copy = m_pullup(mb_copy, i);
        if (mb_copy == NULL)
                return;

        /*
         * fill in the encapsulating IP header.
         */
        ip_copy = mtod(mb_copy, struct ip *);
        *ip_copy = multicast_encap_iphdr;
        if (len < IP_MINFRAGSIZE)
                ip_copy->ip_id = 0;
        else
                ip_copy->ip_id = ip_newid();
        ip_copy->ip_len = htons(len);
        ip_copy->ip_src = vifp->v_lcl_addr;
        ip_copy->ip_dst = vifp->v_rmt_addr;

        /*
         * turn the encapsulated IP header back into a valid one.
         */
        ip = (struct ip *)((char *)ip_copy + sizeof(multicast_encap_iphdr));
        --ip->ip_ttl;
        ip->ip_sum = 0;
        mb_copy->m_data += sizeof(multicast_encap_iphdr);
        ip->ip_sum = in_cksum(mb_copy, ip->ip_hl << 2);
        mb_copy->m_data -= sizeof(multicast_encap_iphdr);

        if (vifp->v_rate_limit <= 0)
                tbf_send_packet(vifp, mb_copy);
        else
                tbf_control(vifp, mb_copy, ip, ntohs(ip_copy->ip_len));
}

/*
 * De-encapsulate a packet and feed it back through ip input.
 */
static void
vif_input(struct mbuf *m, int off, int proto, void *eparg)
{
        struct vif *vifp = eparg;

        KASSERT(vifp != NULL);

        if (proto != ENCAP_PROTO) {
                m_freem(m);
                mrtstat.mrts_bad_tunnel++;
                return;
        }

        m_adj(m, off);
        m_set_rcvif(m, vifp->v_ifp);

        if (__predict_false(!pktq_enqueue(ip_pktq, m, 0))) {
                m_freem(m);
        }
}

/*
 * Check if the packet should be received on the vif denoted by arg.
 * (The encap selection code will call this once per vif since each is
 * registered separately.)
 */
static int
vif_encapcheck(struct mbuf *m, int off, int proto, void *arg)
{
        struct vif *vifp;
        struct ip ip;

#ifdef DIAGNOSTIC
        if (!arg || proto != IPPROTO_IPV4)
                panic("unexpected arg in vif_encapcheck");
#endif

        /*
         * Accept the packet only if the inner header is multicast
         * and the outer header matches a tunnel-mode vif.  Order
         * checks in the hope that common non-matching packets will be
         * rejected quickly.  Assume that unicast IPv4 traffic in a
         * parallel tunnel (e.g. gif(4)) is unlikely.
         */

        /* Obtain the outer IP header and the vif pointer. */
        m_copydata(m, 0, sizeof(ip), (void *)&ip);
        vifp = (struct vif *)arg;

        /*
         * The outer source must match the vif's remote peer address.
         * For a multicast router with several tunnels, this is the
         * only check that will fail on packets in other tunnels,
         * assuming the local address is the same.
         */
        if (!in_hosteq(vifp->v_rmt_addr, ip.ip_src))
                return 0;

        /* The outer destination must match the vif's local address. */
        if (!in_hosteq(vifp->v_lcl_addr, ip.ip_dst))
                return 0;

        /* The vif must be of tunnel type. */
        if ((vifp->v_flags & VIFF_TUNNEL) == 0)
                return 0;

        /* Check that the inner destination is multicast. */
        if (off + sizeof(ip) > m->m_pkthdr.len)
                return 0;
        m_copydata(m, off, sizeof(ip), (void *)&ip);
        if (!IN_MULTICAST(ip.ip_dst.s_addr))
                return 0;

        /*
         * We have checked that both the outer src and dst addresses
         * match the vif, and that the inner destination is multicast
         * (224/5).  By claiming more than 64, we intend to
         * preferentially take packets that also match a parallel
         * gif(4).
         */
        return 32 + 32 + 5;
}

/*
 * Token bucket filter module
 */
static void
tbf_control(struct vif *vifp, struct mbuf *m, struct ip *ip, u_int32_t len)
{

        if (len > MAX_BKT_SIZE) {
                /* drop if packet is too large */
                mrtstat.mrts_pkt2large++;
                m_freem(m);
                return;
        }

        tbf_update_tokens(vifp);

        /*
         * If there are enough tokens, and the queue is empty, send this packet
         * out immediately.  Otherwise, try to insert it on this vif's queue.
         */
        if (vifp->tbf_q_len == 0) {
                if (len <= vifp->tbf_n_tok) {
                        vifp->tbf_n_tok -= len;
                        tbf_send_packet(vifp, m);
                } else {
                        /* queue packet and timeout till later */
                        tbf_queue(vifp, m);
                        callout_reset(&vifp->v_repq_ch, TBF_REPROCESS,
                            tbf_reprocess_q, vifp);
                }
        } else {
                if (vifp->tbf_q_len >= vifp->tbf_max_q_len &&
                    !tbf_dq_sel(vifp, ip)) {
                        /* queue full, and couldn't make room */
                        mrtstat.mrts_q_overflow++;
                        m_freem(m);
                } else {
                        /* queue length low enough, or made room */
                        tbf_queue(vifp, m);
                        tbf_process_q(vifp);
                }
        }
}

/*
 * adds a packet to the queue at the interface
 */
static void
tbf_queue(struct vif *vifp, struct mbuf *m)
{
        int s = splsoftnet();

        /* insert at tail */
        *vifp->tbf_t = m;
        vifp->tbf_t = &m->m_nextpkt;
        vifp->tbf_q_len++;

        splx(s);
}

/*
 * processes the queue at the interface
 */
static void
tbf_process_q(struct vif *vifp)
{
        struct mbuf *m;
        int len;
        int s = splsoftnet();

        /*
         * Loop through the queue at the interface and send as many packets
         * as possible.
         */
        for (m = vifp->tbf_q; m != NULL; m = vifp->tbf_q) {
                len = ntohs(mtod(m, struct ip *)->ip_len);

                /* determine if the packet can be sent */
                if (len <= vifp->tbf_n_tok) {
                        /* if so,
                         * reduce no of tokens, dequeue the packet,
                         * send the packet.
                         */
                        if ((vifp->tbf_q = m->m_nextpkt) == NULL)
                                vifp->tbf_t = &vifp->tbf_q;
                        --vifp->tbf_q_len;

                        m->m_nextpkt = NULL;
                        vifp->tbf_n_tok -= len;
                        tbf_send_packet(vifp, m);
                } else
                        break;
        }
        splx(s);
}

static void
tbf_reprocess_q(void *arg)
{
        struct vif *vifp = arg;

        if (ip_mrouter == NULL)
                return;

        tbf_update_tokens(vifp);
        tbf_process_q(vifp);

        if (vifp->tbf_q_len != 0)
                callout_reset(&vifp->v_repq_ch, TBF_REPROCESS,
                    tbf_reprocess_q, vifp);
}

/* function that will selectively discard a member of the queue
 * based on the precedence value and the priority
 */
static int
tbf_dq_sel(struct vif *vifp, struct ip *ip)
{
        u_int p;
        struct mbuf **mp, *m;
        int s = splsoftnet();

        p = priority(vifp, ip);

        for (mp = &vifp->tbf_q, m = *mp;
            m != NULL;
            mp = &m->m_nextpkt, m = *mp) {
                if (p > priority(vifp, mtod(m, struct ip *))) {
                        if ((*mp = m->m_nextpkt) == NULL)
                                vifp->tbf_t = mp;
                        --vifp->tbf_q_len;

                        m_freem(m);
                        mrtstat.mrts_drop_sel++;
                        splx(s);
                        return 1;
                }
        }
        splx(s);
        return 0;
}

static void
tbf_send_packet(struct vif *vifp, struct mbuf *m)
{
        int error;
        int s = splsoftnet();

        if (vifp->v_flags & VIFF_TUNNEL) {
                /* If tunnel options */
                ip_output(m, NULL, &vifp->v_route, IP_FORWARDING, NULL, NULL);
        } else {
                /* if physical interface option, extract the options and then send */
                struct ip_moptions imo;

                imo.imo_multicast_if_index = if_get_index(vifp->v_ifp);
                imo.imo_multicast_ttl = mtod(m, struct ip *)->ip_ttl - 1;
                imo.imo_multicast_loop = 1;

                error = ip_output(m, NULL, NULL, IP_FORWARDING|IP_MULTICASTOPTS,
                    &imo, NULL);

                if (mrtdebug & DEBUG_XMIT)
                        log(LOG_DEBUG, "phyint_send on vif %ld err %d\n",
                            (long)(vifp - viftable), error);
        }
        splx(s);
}

/* determine the current time and then
 * the elapsed time (between the last time and time now)
 * in milliseconds & update the no. of tokens in the bucket
 */
static void
tbf_update_tokens(struct vif *vifp)
{
        struct timeval tp;
        u_int32_t tm;
        int s = splsoftnet();

        microtime(&tp);

        TV_DELTA(tp, vifp->tbf_last_pkt_t, tm);

        /*
         * This formula is actually
         * "time in seconds" * "bytes/second".
         *
         * (tm / 1000000) * (v_rate_limit * 1000 * (1000/1024) / 8)
         *
         * The (1000/1024) was introduced in add_vif to optimize
         * this divide into a shift.
         */
        vifp->tbf_n_tok += tm * vifp->v_rate_limit / 8192;
        vifp->tbf_last_pkt_t = tp;

        if (vifp->tbf_n_tok > MAX_BKT_SIZE)
                vifp->tbf_n_tok = MAX_BKT_SIZE;

        splx(s);
}

static int
priority(struct vif *vifp, struct ip *ip)
{
        int prio = 50;  /* the lowest priority -- default case */

        /* temporary hack; may add general packet classifier some day */

        /*
         * XXX XXX: We're reading the UDP header, but we didn't ensure
         * it was present in the packet.
         */

        /*
         * The UDP port space is divided up into four priority ranges:
         * [0, 16384)     : unclassified - lowest priority
         * [16384, 32768) : audio - highest priority
         * [32768, 49152) : whiteboard - medium priority
         * [49152, 65536) : video - low priority
         */
        if (ip->ip_p == IPPROTO_UDP) {
                struct udphdr *udp = (struct udphdr *)(((char *)ip) + (ip->ip_hl << 2));

                switch (ntohs(udp->uh_dport) & 0xc000) {
                case 0x4000:
                        prio = 70;
                        break;
                case 0x8000:
                        prio = 60;
                        break;
                case 0xc000:
                        prio = 55;
                        break;
                }

                if (tbfdebug > 1)
                        log(LOG_DEBUG, "port %x prio %d\n",
                            ntohs(udp->uh_dport), prio);
        }

        return prio;
}

/*
 * Code for bandwidth monitors
 */

/*
 * Define common interface for timeval-related methods
 */
#define BW_TIMEVALCMP(tvp, uvp, cmp) timercmp((tvp), (uvp), cmp)
#define BW_TIMEVALDECR(vvp, uvp) timersub((vvp), (uvp), (vvp))
#define BW_TIMEVALADD(vvp, uvp) timeradd((vvp), (uvp), (vvp))

static uint32_t
compute_bw_meter_flags(struct bw_upcall *req)
{
        uint32_t flags = 0;

        if (req->bu_flags & BW_UPCALL_UNIT_PACKETS)
                flags |= BW_METER_UNIT_PACKETS;
        if (req->bu_flags & BW_UPCALL_UNIT_BYTES)
                flags |= BW_METER_UNIT_BYTES;
        if (req->bu_flags & BW_UPCALL_GEQ)
                flags |= BW_METER_GEQ;
        if (req->bu_flags & BW_UPCALL_LEQ)
                flags |= BW_METER_LEQ;

        return flags;
}

/*
 * Add a bw_meter entry
 */
static int
add_bw_upcall(struct bw_upcall *req)
{
        int s;
        struct mfc *mfc;
        struct timeval delta = { BW_UPCALL_THRESHOLD_INTERVAL_MIN_SEC,
                BW_UPCALL_THRESHOLD_INTERVAL_MIN_USEC };
        struct timeval now;
        struct bw_meter *x;
        uint32_t flags;

        if (!(mrt_api_config & MRT_MFC_BW_UPCALL))
                return EOPNOTSUPP;

        /* Test if the flags are valid */
        if (!(req->bu_flags & (BW_UPCALL_UNIT_PACKETS | BW_UPCALL_UNIT_BYTES)))
                return EINVAL;
        if (!(req->bu_flags & (BW_UPCALL_GEQ | BW_UPCALL_LEQ)))
                return EINVAL;
        if ((req->bu_flags & (BW_UPCALL_GEQ | BW_UPCALL_LEQ))
            == (BW_UPCALL_GEQ | BW_UPCALL_LEQ))
                return EINVAL;

        /* Test if the threshold time interval is valid */
        if (BW_TIMEVALCMP(&req->bu_threshold.b_time, &delta, <))
                return EINVAL;

        flags = compute_bw_meter_flags(req);

        /*
         * Find if we have already same bw_meter entry
         */
        s = splsoftnet();
        mfc = mfc_find(&req->bu_src, &req->bu_dst);
        if (mfc == NULL) {
                splx(s);
                return EADDRNOTAVAIL;
        }
        for (x = mfc->mfc_bw_meter; x != NULL; x = x->bm_mfc_next) {
                if ((BW_TIMEVALCMP(&x->bm_threshold.b_time,
                    &req->bu_threshold.b_time, ==)) &&
                    (x->bm_threshold.b_packets == req->bu_threshold.b_packets) &&
                    (x->bm_threshold.b_bytes == req->bu_threshold.b_bytes) &&
                    (x->bm_flags & BW_METER_USER_FLAGS) == flags)  {
                        splx(s);
                        return 0;               /* XXX Already installed */
                }
        }

        /* Allocate the new bw_meter entry */
        x = kmem_intr_alloc(sizeof(*x), KM_NOSLEEP);
        if (x == NULL) {
                splx(s);
                return ENOBUFS;
        }

        /* Set the new bw_meter entry */
        x->bm_threshold.b_time = req->bu_threshold.b_time;
        microtime(&now);
        x->bm_start_time = now;
        x->bm_threshold.b_packets = req->bu_threshold.b_packets;
        x->bm_threshold.b_bytes = req->bu_threshold.b_bytes;
        x->bm_measured.b_packets = 0;
        x->bm_measured.b_bytes = 0;
        x->bm_flags = flags;
        x->bm_time_next = NULL;
        x->bm_time_hash = BW_METER_BUCKETS;

        /* Add the new bw_meter entry to the front of entries for this MFC */
        x->bm_mfc = mfc;
        x->bm_mfc_next = mfc->mfc_bw_meter;
        mfc->mfc_bw_meter = x;
        schedule_bw_meter(x, &now);
        splx(s);

        return 0;
}

static void
free_bw_list(struct bw_meter *list)
{
        while (list != NULL) {
                struct bw_meter *x = list;

                list = list->bm_mfc_next;
                unschedule_bw_meter(x);
                kmem_intr_free(x, sizeof(*x));
        }
}

/*
 * Delete one or multiple bw_meter entries
 */
static int
del_bw_upcall(struct bw_upcall *req)
{
        int s;
        struct mfc *mfc;
        struct bw_meter *x;

        if (!(mrt_api_config & MRT_MFC_BW_UPCALL))
                return EOPNOTSUPP;

        s = splsoftnet();
        /* Find the corresponding MFC entry */
        mfc = mfc_find(&req->bu_src, &req->bu_dst);
        if (mfc == NULL) {
                splx(s);
                return EADDRNOTAVAIL;
        } else if (req->bu_flags & BW_UPCALL_DELETE_ALL) {
                /*
                 * Delete all bw_meter entries for this mfc
                 */
                struct bw_meter *list;

                list = mfc->mfc_bw_meter;
                mfc->mfc_bw_meter = NULL;
                free_bw_list(list);
                splx(s);
                return 0;
        } else {                        /* Delete a single bw_meter entry */
                struct bw_meter *prev;
                uint32_t flags = 0;

                flags = compute_bw_meter_flags(req);

                /* Find the bw_meter entry to delete */
                for (prev = NULL, x = mfc->mfc_bw_meter; x != NULL;
                     prev = x, x = x->bm_mfc_next) {
                        if ((BW_TIMEVALCMP(&x->bm_threshold.b_time,
                            &req->bu_threshold.b_time, ==)) &&
                            (x->bm_threshold.b_packets == req->bu_threshold.b_packets) &&
                            (x->bm_threshold.b_bytes == req->bu_threshold.b_bytes) &&
                            (x->bm_flags & BW_METER_USER_FLAGS) == flags)
                                break;
                }
                if (x != NULL) { /* Delete entry from the list for this MFC */
                        if (prev != NULL)
                                prev->bm_mfc_next = x->bm_mfc_next;     /* remove from middle*/
                        else
                                x->bm_mfc->mfc_bw_meter = x->bm_mfc_next;/* new head of list */

                        unschedule_bw_meter(x);
                        splx(s);
                        /* Free the bw_meter entry */
                        kmem_intr_free(x, sizeof(*x));
                        return 0;
                } else {
                        splx(s);
                        return EINVAL;
                }
        }
        /* NOTREACHED */
}

/*
 * Perform bandwidth measurement processing that may result in an upcall
 */
static void
bw_meter_receive_packet(struct bw_meter *x, int plen, struct timeval *nowp)
{
        struct timeval delta;

        delta = *nowp;
        BW_TIMEVALDECR(&delta, &x->bm_start_time);

        if (x->bm_flags & BW_METER_GEQ) {
                /*
                 * Processing for ">=" type of bw_meter entry
                 */
                if (BW_TIMEVALCMP(&delta, &x->bm_threshold.b_time, >)) {
                        /* Reset the bw_meter entry */
                        x->bm_start_time = *nowp;
                        x->bm_measured.b_packets = 0;
                        x->bm_measured.b_bytes = 0;
                        x->bm_flags &= ~BW_METER_UPCALL_DELIVERED;
                }

                /* Record that a packet is received */
                x->bm_measured.b_packets++;
                x->bm_measured.b_bytes += plen;

                /*
                 * Test if we should deliver an upcall
                 */
                if (!(x->bm_flags & BW_METER_UPCALL_DELIVERED)) {
                        if (((x->bm_flags & BW_METER_UNIT_PACKETS) &&
                                 (x->bm_measured.b_packets >= x->bm_threshold.b_packets)) ||
                                ((x->bm_flags & BW_METER_UNIT_BYTES) &&
                                 (x->bm_measured.b_bytes >= x->bm_threshold.b_bytes))) {
                                /* Prepare an upcall for delivery */
                                bw_meter_prepare_upcall(x, nowp);
                                x->bm_flags |= BW_METER_UPCALL_DELIVERED;
                        }
                }
        } else if (x->bm_flags & BW_METER_LEQ) {
                /*
                 * Processing for "<=" type of bw_meter entry
                 */
                if (BW_TIMEVALCMP(&delta, &x->bm_threshold.b_time, >)) {
                        /*
                         * We are behind time with the multicast forwarding table
                         * scanning for "<=" type of bw_meter entries, so test now
                         * if we should deliver an upcall.
                         */
                        if (((x->bm_flags & BW_METER_UNIT_PACKETS) &&
                                 (x->bm_measured.b_packets <= x->bm_threshold.b_packets)) ||
                                ((x->bm_flags & BW_METER_UNIT_BYTES) &&
                                 (x->bm_measured.b_bytes <= x->bm_threshold.b_bytes))) {
                                /* Prepare an upcall for delivery */
                                bw_meter_prepare_upcall(x, nowp);
                        }
                        /* Reschedule the bw_meter entry */
                        unschedule_bw_meter(x);
                        schedule_bw_meter(x, nowp);
                }

                /* Record that a packet is received */
                x->bm_measured.b_packets++;
                x->bm_measured.b_bytes += plen;

                /*
                 * Test if we should restart the measuring interval
                 */
                if ((x->bm_flags & BW_METER_UNIT_PACKETS &&
                     x->bm_measured.b_packets <= x->bm_threshold.b_packets) ||
                    (x->bm_flags & BW_METER_UNIT_BYTES &&
                     x->bm_measured.b_bytes <= x->bm_threshold.b_bytes)) {
                        /* Don't restart the measuring interval */
                } else {
                        /* Do restart the measuring interval */
                        /*
                         * XXX: note that we don't unschedule and schedule, because this
                         * might be too much overhead per packet. Instead, when we process
                         * all entries for a given timer hash bin, we check whether it is
                         * really a timeout. If not, we reschedule at that time.
                         */
                        x->bm_start_time = *nowp;
                        x->bm_measured.b_packets = 0;
                        x->bm_measured.b_bytes = 0;
                        x->bm_flags &= ~BW_METER_UPCALL_DELIVERED;
                }
        }
}

/*
 * Prepare a bandwidth-related upcall
 */
static void
bw_meter_prepare_upcall(struct bw_meter *x, struct timeval *nowp)
{
        struct timeval delta;
        struct bw_upcall *u;

        /*
         * Compute the measured time interval
         */
        delta = *nowp;
        BW_TIMEVALDECR(&delta, &x->bm_start_time);

        /*
         * If there are too many pending upcalls, deliver them now
         */
        if (bw_upcalls_n >= BW_UPCALLS_MAX)
                bw_upcalls_send();

        /*
         * Set the bw_upcall entry
         */
        u = &bw_upcalls[bw_upcalls_n++];
        u->bu_src = x->bm_mfc->mfc_origin;
        u->bu_dst = x->bm_mfc->mfc_mcastgrp;
        u->bu_threshold.b_time = x->bm_threshold.b_time;
        u->bu_threshold.b_packets = x->bm_threshold.b_packets;
        u->bu_threshold.b_bytes = x->bm_threshold.b_bytes;
        u->bu_measured.b_time = delta;
        u->bu_measured.b_packets = x->bm_measured.b_packets;
        u->bu_measured.b_bytes = x->bm_measured.b_bytes;
        u->bu_flags = 0;
        if (x->bm_flags & BW_METER_UNIT_PACKETS)
                u->bu_flags |= BW_UPCALL_UNIT_PACKETS;
        if (x->bm_flags & BW_METER_UNIT_BYTES)
                u->bu_flags |= BW_UPCALL_UNIT_BYTES;
        if (x->bm_flags & BW_METER_GEQ)
                u->bu_flags |= BW_UPCALL_GEQ;
        if (x->bm_flags & BW_METER_LEQ)
                u->bu_flags |= BW_UPCALL_LEQ;
}

/*
 * Send the pending bandwidth-related upcalls
 */
static void
bw_upcalls_send(void)
{
        struct mbuf *m;
        int len = bw_upcalls_n * sizeof(bw_upcalls[0]);
        struct sockaddr_in k_igmpsrc = {
                .sin_len = sizeof(k_igmpsrc),
                .sin_family = AF_INET,
        };
        static struct igmpmsg igmpmsg = {
                0,              /* unused1 */
                0,              /* unused2 */
                IGMPMSG_BW_UPCALL,/* im_msgtype */
                0,              /* im_mbz */
                0,              /* im_vif */
                0,              /* unused3 */
                { 0 },          /* im_src */
                { 0 }           /* im_dst */
        };

        if (bw_upcalls_n == 0)
                return;                 /* No pending upcalls */

        bw_upcalls_n = 0;

        /*
         * Allocate a new mbuf, initialize it with the header and
         * the payload for the pending calls.
         */
        MGETHDR(m, M_DONTWAIT, MT_HEADER);
        if (m == NULL) {
                log(LOG_WARNING, "bw_upcalls_send: cannot allocate mbuf\n");
                return;
        }

        m->m_len = m->m_pkthdr.len = 0;
        m_copyback(m, 0, sizeof(struct igmpmsg), (void *)&igmpmsg);
        m_copyback(m, sizeof(struct igmpmsg), len, (void *)&bw_upcalls[0]);

        /*
         * Send the upcalls
         * XXX do we need to set the address in k_igmpsrc ?
         */
        mrtstat.mrts_upcalls++;
        if (socket_send(ip_mrouter, m, &k_igmpsrc) < 0) {
                log(LOG_WARNING, "bw_upcalls_send: ip_mrouter socket queue full\n");
                ++mrtstat.mrts_upq_sockfull;
        }
}

/*
 * Compute the timeout hash value for the bw_meter entries
 */
#define BW_METER_TIMEHASH(bw_meter, hash)                               \
    do {                                                                \
        struct timeval next_timeval = (bw_meter)->bm_start_time;        \
        BW_TIMEVALADD(&next_timeval, &(bw_meter)->bm_threshold.b_time); \
        (hash) = next_timeval.tv_sec;                                   \
        if (next_timeval.tv_usec)                                       \
                (hash)++; /* XXX: make sure we don't timeout early */   \
        (hash) %= BW_METER_BUCKETS;                                     \
    } while (/*CONSTCOND*/ 0)

/*
 * Schedule a timer to process periodically bw_meter entry of type "<="
 * by linking the entry in the proper hash bucket.
 */
static void
schedule_bw_meter(struct bw_meter *x, struct timeval *nowp)
{
        int time_hash;

        if (!(x->bm_flags & BW_METER_LEQ))
                return;         /* XXX: we schedule timers only for "<=" entries */

        /*
         * Reset the bw_meter entry
         */
        x->bm_start_time = *nowp;
        x->bm_measured.b_packets = 0;
        x->bm_measured.b_bytes = 0;
        x->bm_flags &= ~BW_METER_UPCALL_DELIVERED;

        /*
         * Compute the timeout hash value and insert the entry
         */
        BW_METER_TIMEHASH(x, time_hash);
        x->bm_time_next = bw_meter_timers[time_hash];
        bw_meter_timers[time_hash] = x;
        x->bm_time_hash = time_hash;
}

/*
 * Unschedule the periodic timer that processes bw_meter entry of type "<="
 * by removing the entry from the proper hash bucket.
 */
static void
unschedule_bw_meter(struct bw_meter *x)
{
        int time_hash;
        struct bw_meter *prev, *tmp;

        if (!(x->bm_flags & BW_METER_LEQ))
                return;         /* XXX: we schedule timers only for "<=" entries */

        /*
         * Compute the timeout hash value and delete the entry
         */
        time_hash = x->bm_time_hash;
        if (time_hash >= BW_METER_BUCKETS)
                return;         /* Entry was not scheduled */

        for (prev = NULL, tmp = bw_meter_timers[time_hash];
             tmp != NULL; prev = tmp, tmp = tmp->bm_time_next)
                if (tmp == x)
                        break;

        if (tmp == NULL)
                panic("unschedule_bw_meter: bw_meter entry not found");

        if (prev != NULL)
                prev->bm_time_next = x->bm_time_next;
        else
                bw_meter_timers[time_hash] = x->bm_time_next;

        x->bm_time_next = NULL;
        x->bm_time_hash = BW_METER_BUCKETS;
}

/*
 * Process all "<=" type of bw_meter that should be processed now,
 * and for each entry prepare an upcall if necessary. Each processed
 * entry is rescheduled again for the (periodic) processing.
 *
 * This is run periodically (once per second normally). On each round,
 * all the potentially matching entries are in the hash slot that we are
 * looking at.
 */
static void
bw_meter_process(void)
{
        int s;
        static uint32_t last_tv_sec;    /* last time we processed this */

        uint32_t loops;
        int i;
        struct timeval now, process_endtime;

        microtime(&now);
        if (last_tv_sec == now.tv_sec)
                return;         /* nothing to do */

        loops = now.tv_sec - last_tv_sec;
        last_tv_sec = now.tv_sec;
        if (loops > BW_METER_BUCKETS)
                loops = BW_METER_BUCKETS;

        s = splsoftnet();
        /*
         * Process all bins of bw_meter entries from the one after the last
         * processed to the current one. On entry, i points to the last bucket
         * visited, so we need to increment i at the beginning of the loop.
         */
        for (i = (now.tv_sec - loops) % BW_METER_BUCKETS; loops > 0; loops--) {
                struct bw_meter *x, *tmp_list;

                if (++i >= BW_METER_BUCKETS)
                        i = 0;

                /* Disconnect the list of bw_meter entries from the bin */
                tmp_list = bw_meter_timers[i];
                bw_meter_timers[i] = NULL;

                /* Process the list of bw_meter entries */
                while (tmp_list != NULL) {
                        x = tmp_list;
                        tmp_list = tmp_list->bm_time_next;

                        /* Test if the time interval is over */
                        process_endtime = x->bm_start_time;
                        BW_TIMEVALADD(&process_endtime, &x->bm_threshold.b_time);
                        if (BW_TIMEVALCMP(&process_endtime, &now, >)) {
                                /* Not yet: reschedule, but don't reset */
                                int time_hash;

                                BW_METER_TIMEHASH(x, time_hash);
                                if (time_hash == i && process_endtime.tv_sec == now.tv_sec) {
                                        /*
                                         * XXX: somehow the bin processing is a bit ahead of time.
                                         * Put the entry in the next bin.
                                         */
                                        if (++time_hash >= BW_METER_BUCKETS)
                                                time_hash = 0;
                                }
                                x->bm_time_next = bw_meter_timers[time_hash];
                                bw_meter_timers[time_hash] = x;
                                x->bm_time_hash = time_hash;

                                continue;
                        }

                        /*
                         * Test if we should deliver an upcall
                         */
                        if (((x->bm_flags & BW_METER_UNIT_PACKETS) &&
                            (x->bm_measured.b_packets <= x->bm_threshold.b_packets)) ||
                            ((x->bm_flags & BW_METER_UNIT_BYTES) &&
                            (x->bm_measured.b_bytes <= x->bm_threshold.b_bytes))) {
                                /* Prepare an upcall for delivery */
                                bw_meter_prepare_upcall(x, &now);
                        }

                        /*
                          * Reschedule for next processing
                         */
                        schedule_bw_meter(x, &now);
                }
        }

        /* Send all upcalls that are pending delivery */
        bw_upcalls_send();

        splx(s);
}

/*
 * A periodic function for sending all upcalls that are pending delivery
 */
static void
expire_bw_upcalls_send(void *unused)
{
        int s;

        s = splsoftnet();
        bw_upcalls_send();
        splx(s);

        callout_reset(&bw_upcalls_ch, BW_UPCALLS_PERIOD,
            expire_bw_upcalls_send, NULL);
}

/*
 * A periodic function for periodic scanning of the multicast forwarding
 * table for processing all "<=" bw_meter entries.
 */
static void
expire_bw_meter_process(void *unused)
{
        if (mrt_api_config & MRT_MFC_BW_UPCALL)
                bw_meter_process();

        callout_reset(&bw_meter_ch, BW_METER_PERIOD,
            expire_bw_meter_process, NULL);
}

/*
 * End of bandwidth monitoring code
 */

#ifdef PIM
/*
 * Send the packet up to the user daemon, or eventually do kernel encapsulation
 */
static int
pim_register_send(struct ip *ip, struct vif *vifp, struct mbuf *m,
    struct mfc *rt)
{
        struct mbuf *mb_copy, *mm;

        if (mrtdebug & DEBUG_PIM)
                log(LOG_DEBUG, "pim_register_send: \n");

        mb_copy = pim_register_prepare(ip, m);
        if (mb_copy == NULL)
                return ENOBUFS;

        /*
         * Send all the fragments. Note that the mbuf for each fragment
         * is freed by the sending machinery.
         */
        for (mm = mb_copy; mm; mm = mb_copy) {
                mb_copy = mm->m_nextpkt;
                mm->m_nextpkt = NULL;
                mm = m_pullup(mm, sizeof(struct ip));
                if (mm != NULL) {
                        ip = mtod(mm, struct ip *);
                        if ((mrt_api_config & MRT_MFC_RP) &&
                            !in_nullhost(rt->mfc_rp)) {
                                pim_register_send_rp(ip, vifp, mm, rt);
                        } else {
                                pim_register_send_upcall(ip, vifp, mm, rt);
                        }
                }
        }

        return 0;
}

/*
 * Return a copy of the data packet that is ready for PIM Register
 * encapsulation.
 * XXX: Note that in the returned copy the IP header is a valid one.
 */
static struct mbuf *
pim_register_prepare(struct ip *ip, struct mbuf *m)
{
        struct mbuf *mb_copy = NULL;
        int mtu;

        /* Take care of delayed checksums */
        if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                in_undefer_cksum_tcpudp(m);
                m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv4|M_CSUM_UDPv4);
        }

        /*
         * Copy the old packet & pullup its IP header into the
         * new mbuf so we can modify it.
         */
        mb_copy = m_copypacket(m, M_DONTWAIT);
        if (mb_copy == NULL)
                return NULL;
        mb_copy = m_pullup(mb_copy, ip->ip_hl << 2);
        if (mb_copy == NULL)
                return NULL;

        /* take care of the TTL */
        ip = mtod(mb_copy, struct ip *);
        --ip->ip_ttl;

        /* Compute the MTU after the PIM Register encapsulation */
        mtu = 0xffff - sizeof(pim_encap_iphdr) - sizeof(pim_encap_pimhdr);

        if (ntohs(ip->ip_len) <= mtu) {
                /* Turn the IP header into a valid one */
                ip->ip_sum = 0;
                ip->ip_sum = in_cksum(mb_copy, ip->ip_hl << 2);
        } else {
                /* Fragment the packet */
                if (ip_fragment(mb_copy, NULL, mtu) != 0) {
                        /* XXX: mb_copy was freed by ip_fragment() */
                        return NULL;
                }
        }
        return mb_copy;
}

/*
 * Send an upcall with the data packet to the user-level process.
 */
static int
pim_register_send_upcall(struct ip *ip, struct vif *vifp,
    struct mbuf *mb_copy, struct mfc *rt)
{
        struct mbuf *mb_first;
        int len = ntohs(ip->ip_len);
        struct igmpmsg *im;
        struct sockaddr_in k_igmpsrc = {
                .sin_len = sizeof(k_igmpsrc),
                .sin_family = AF_INET,
        };

        /*
         * Add a new mbuf with an upcall header
         */
        MGETHDR(mb_first, M_DONTWAIT, MT_HEADER);
        if (mb_first == NULL) {
                m_freem(mb_copy);
                return ENOBUFS;
        }
        mb_first->m_data += max_linkhdr;
        mb_first->m_pkthdr.len = len + sizeof(struct igmpmsg);
        mb_first->m_len = sizeof(struct igmpmsg);
        mb_first->m_next = mb_copy;

        /* Send message to routing daemon */
        im = mtod(mb_first, struct igmpmsg *);
        im->im_msgtype  = IGMPMSG_WHOLEPKT;
        im->im_mbz      = 0;
        im->im_vif      = vifp - viftable;
        im->im_src      = ip->ip_src;
        im->im_dst      = ip->ip_dst;

        k_igmpsrc.sin_addr      = ip->ip_src;

        mrtstat.mrts_upcalls++;

        if (socket_send(ip_mrouter, mb_first, &k_igmpsrc) < 0) {
                if (mrtdebug & DEBUG_PIM)
                        log(LOG_WARNING,
                            "mcast: pim_register_send_upcall: ip_mrouter socket queue full\n");
                ++mrtstat.mrts_upq_sockfull;
                return ENOBUFS;
        }

        /* Keep statistics */
        pimstat.pims_snd_registers_msgs++;
        pimstat.pims_snd_registers_bytes += len;

        return 0;
}

/*
 * Encapsulate the data packet in PIM Register message and send it to the RP.
 */
static int
pim_register_send_rp(struct ip *ip, struct vif *vifp,
    struct mbuf *mb_copy, struct mfc *rt)
{
        struct mbuf *mb_first;
        struct ip *ip_outer;
        struct pim_encap_pimhdr *pimhdr;
        int len = ntohs(ip->ip_len);
        vifi_t vifi = rt->mfc_parent;

        if ((vifi >= numvifs) || in_nullhost(viftable[vifi].v_lcl_addr)) {
                m_freem(mb_copy);
                return EADDRNOTAVAIL;           /* The iif vif is invalid */
        }

        /*
         * Add a new mbuf with the encapsulating header
         */
        MGETHDR(mb_first, M_DONTWAIT, MT_HEADER);
        if (mb_first == NULL) {
                m_freem(mb_copy);
                return ENOBUFS;
        }
        mb_first->m_data += max_linkhdr;
        mb_first->m_len = sizeof(pim_encap_iphdr) + sizeof(pim_encap_pimhdr);
        mb_first->m_next = mb_copy;

        mb_first->m_pkthdr.len = len + mb_first->m_len;

        /*
         * Fill in the encapsulating IP and PIM header
         */
        ip_outer = mtod(mb_first, struct ip *);
        *ip_outer = pim_encap_iphdr;
        if (mb_first->m_pkthdr.len < IP_MINFRAGSIZE)
                ip_outer->ip_id = 0;
        else
                ip_outer->ip_id = ip_newid();
        ip_outer->ip_len = htons(len + sizeof(pim_encap_iphdr) +
            sizeof(pim_encap_pimhdr));
        ip_outer->ip_src = viftable[vifi].v_lcl_addr;
        ip_outer->ip_dst = rt->mfc_rp;
        /*
         * Copy the inner header TOS to the outer header, and take care of the
         * IP_DF bit.
         */
        ip_outer->ip_tos = ip->ip_tos;
        if (ntohs(ip->ip_off) & IP_DF)
                ip_outer->ip_off |= htons(IP_DF);
        pimhdr = (struct pim_encap_pimhdr *)((char *)ip_outer
            + sizeof(pim_encap_iphdr));
        *pimhdr = pim_encap_pimhdr;
        /* If the iif crosses a border, set the Border-bit */
        if (rt->mfc_flags[vifi] & MRT_MFC_FLAGS_BORDER_VIF & mrt_api_config)
                pimhdr->flags |= htonl(PIM_BORDER_REGISTER);

        mb_first->m_data += sizeof(pim_encap_iphdr);
        pimhdr->pim.pim_cksum = in_cksum(mb_first, sizeof(pim_encap_pimhdr));
        mb_first->m_data -= sizeof(pim_encap_iphdr);

        if (vifp->v_rate_limit == 0)
                tbf_send_packet(vifp, mb_first);
        else
                tbf_control(vifp, mb_first, ip, ntohs(ip_outer->ip_len));

        /* Keep statistics */
        pimstat.pims_snd_registers_msgs++;
        pimstat.pims_snd_registers_bytes += len;

        return 0;
}

/*
 * PIM-SMv2 and PIM-DM messages processing.
 * Receives and verifies the PIM control messages, and passes them
 * up to the listening socket, using rip_input().
 * The only message with special processing is the PIM_REGISTER message
 * (used by PIM-SM): the PIM header is stripped off, and the inner packet
 * is passed to if_simloop().
 */
void
pim_input(struct mbuf *m, int off, int proto)
{
        struct ip *ip = mtod(m, struct ip *);
        struct pim *pim;
        int minlen;
        int datalen;
        int ip_tos;
        int iphlen;

        iphlen = off;
        datalen = ntohs(ip->ip_len) - iphlen;

        /* Keep statistics */
        pimstat.pims_rcv_total_msgs++;
        pimstat.pims_rcv_total_bytes += datalen;

        /*
         * Validate lengths
         */
        if (datalen < PIM_MINLEN) {
                pimstat.pims_rcv_tooshort++;
                log(LOG_ERR, "pim_input: packet size too small %d from %lx\n",
                    datalen, (u_long)ip->ip_src.s_addr);
                m_freem(m);
                return;
        }

        /*
         * If the packet is at least as big as a REGISTER, go ahead
         * and grab the PIM REGISTER header size, to avoid another
         * possible m_pullup() later.
         *
         * PIM_MINLEN       == pimhdr + u_int32_t == 4 + 4 = 8
         * PIM_REG_MINLEN   == pimhdr + reghdr + encap_iphdr == 4 + 4 + 20 = 28
         */
        minlen = iphlen + (datalen >= PIM_REG_MINLEN ? PIM_REG_MINLEN : PIM_MINLEN);

        /*
         * Get the IP and PIM headers in contiguous memory, and
         * possibly the PIM REGISTER header.
         */
        if ((m->m_flags & M_EXT || m->m_len < minlen) &&
            (m = m_pullup(m, minlen)) == NULL) {
                log(LOG_ERR, "pim_input: m_pullup failure\n");
                return;
        }
        ip = mtod(m, struct ip *);
        ip_tos = ip->ip_tos;

        /* adjust mbuf to point to the PIM header */
        m->m_data += iphlen;
        m->m_len  -= iphlen;
        pim = mtod(m, struct pim *);

        /*
         * Validate checksum. If PIM REGISTER, exclude the data packet.
         *
         * XXX: some older PIMv2 implementations don't make this distinction,
         * so for compatibility reason perform the checksum over part of the
         * message, and if error, then over the whole message.
         */
        if (PIM_VT_T(pim->pim_vt) == PIM_REGISTER && in_cksum(m, PIM_MINLEN) == 0) {
                /* do nothing, checksum okay */
        } else if (in_cksum(m, datalen)) {
                pimstat.pims_rcv_badsum++;
                if (mrtdebug & DEBUG_PIM)
                        log(LOG_DEBUG, "pim_input: invalid checksum\n");
                m_freem(m);
                return;
        }

        /* PIM version check */
        if (PIM_VT_V(pim->pim_vt) < PIM_VERSION) {
                pimstat.pims_rcv_badversion++;
                log(LOG_ERR, "pim_input: incorrect version %d, expecting %d\n",
                    PIM_VT_V(pim->pim_vt), PIM_VERSION);
                m_freem(m);
                return;
        }

        /* restore mbuf back to the outer IP */
        m->m_data -= iphlen;
        m->m_len  += iphlen;

        if (PIM_VT_T(pim->pim_vt) == PIM_REGISTER) {
                /*
                 * Since this is a REGISTER, we'll make a copy of the register
                 * headers ip + pim + u_int32 + encap_ip, to be passed up to the
                 * routing daemon.
                 */
                int s;
                struct sockaddr_in dst = {
                        .sin_len = sizeof(dst),
                        .sin_family = AF_INET,
                };
                struct mbuf *mcp;
                struct ip *encap_ip;
                u_int32_t *reghdr;
                struct ifnet *vifp;

                s = splsoftnet();
                if ((reg_vif_num >= numvifs) || (reg_vif_num == VIFI_INVALID)) {
                        splx(s);
                        if (mrtdebug & DEBUG_PIM)
                                log(LOG_DEBUG,
                                    "pim_input: register vif not set: %d\n", reg_vif_num);
                        m_freem(m);
                        return;
                }
                /* XXX need refcnt? */
                vifp = viftable[reg_vif_num].v_ifp;
                splx(s);

                /*
                 * Validate length
                 */
                if (datalen < PIM_REG_MINLEN) {
                        pimstat.pims_rcv_tooshort++;
                        pimstat.pims_rcv_badregisters++;
                        log(LOG_ERR,
                            "pim_input: register packet size too small %d from %lx\n",
                            datalen, (u_long)ip->ip_src.s_addr);
                        m_freem(m);
                        return;
                }

                reghdr = (u_int32_t *)(pim + 1);
                encap_ip = (struct ip *)(reghdr + 1);

                if (mrtdebug & DEBUG_PIM) {
                        log(LOG_DEBUG,
                            "pim_input[register], encap_ip: %lx -> %lx, encap_ip len %d\n",
                            (u_long)ntohl(encap_ip->ip_src.s_addr),
                            (u_long)ntohl(encap_ip->ip_dst.s_addr),
                            ntohs(encap_ip->ip_len));
                }

                /* verify the version number of the inner packet */
                if (encap_ip->ip_v != IPVERSION) {
                        pimstat.pims_rcv_badregisters++;
                        if (mrtdebug & DEBUG_PIM) {
                                log(LOG_DEBUG, "pim_input: invalid IP version (%d) "
                                    "of the inner packet\n", encap_ip->ip_v);
                        }
                        m_freem(m);
                        return;
                }

                /* verify the inner packet doesn't have options */
                if (encap_ip->ip_hl != (sizeof(struct ip) >> 2)) {
                        pimstat.pims_rcv_badregisters++;
                        m_freem(m);
                        return;
                }

                /* verify the inner packet is destined to a mcast group */
                if (!IN_MULTICAST(encap_ip->ip_dst.s_addr)) {
                        pimstat.pims_rcv_badregisters++;
                         if (mrtdebug & DEBUG_PIM)
                                log(LOG_DEBUG,
                                    "pim_input: inner packet of register is not "
                                    "multicast %lx\n",
                                    (u_long)ntohl(encap_ip->ip_dst.s_addr));
                        m_freem(m);
                        return;
                }

                /* If a NULL_REGISTER, pass it to the daemon */
                if ((ntohl(*reghdr) & PIM_NULL_REGISTER))
                        goto pim_input_to_daemon;

                /*
                 * Copy the TOS from the outer IP header to the inner IP header.
                 */
                if (encap_ip->ip_tos != ip_tos) {
                        /* Outer TOS -> inner TOS */
                        encap_ip->ip_tos = ip_tos;
                        /* Recompute the inner header checksum. Sigh... */

                        /* adjust mbuf to point to the inner IP header */
                        m->m_data += (iphlen + PIM_MINLEN);
                        m->m_len  -= (iphlen + PIM_MINLEN);

                        encap_ip->ip_sum = 0;
                        encap_ip->ip_sum = in_cksum(m, encap_ip->ip_hl << 2);

                        /* restore mbuf to point back to the outer IP header */
                        m->m_data -= (iphlen + PIM_MINLEN);
                        m->m_len  += (iphlen + PIM_MINLEN);
                }

                /*
                 * Decapsulate the inner IP packet and loopback to forward it
                 * as a normal multicast packet. Also, make a copy of the
                 *     outer_iphdr + pimhdr + reghdr + encap_iphdr
                 * to pass to the daemon later, so it can take the appropriate
                 * actions (e.g., send back PIM_REGISTER_STOP).
                 * XXX: here m->m_data points to the outer IP header.
                 */
                mcp = m_copym(m, 0, iphlen + PIM_REG_MINLEN, M_DONTWAIT);
                if (mcp == NULL) {
                        log(LOG_ERR,
                            "pim_input: pim register: could not copy register head\n");
                        m_freem(m);
                        return;
                }

                /* Keep statistics */
                /* XXX: registers_bytes include only the encap. mcast pkt */
                pimstat.pims_rcv_registers_msgs++;
                pimstat.pims_rcv_registers_bytes += ntohs(encap_ip->ip_len);

                /*
                 * forward the inner ip packet; point m_data at the inner ip.
                 */
                m_adj(m, iphlen + PIM_MINLEN);

                if (mrtdebug & DEBUG_PIM) {
                        log(LOG_DEBUG,
                            "pim_input: forwarding decapsulated register: "
                            "src %lx, dst %lx, vif %d\n",
                            (u_long)ntohl(encap_ip->ip_src.s_addr),
                            (u_long)ntohl(encap_ip->ip_dst.s_addr),
                            reg_vif_num);
                }
                /* NB: vifp was collected above; can it change on us? */
                looutput(vifp, m, (struct sockaddr *)&dst, NULL);

                /* prepare the register head to send to the mrouting daemon */
                m = mcp;
        }

pim_input_to_daemon:
        /*
         * Pass the PIM message up to the daemon; if it is a Register message,
         * pass the 'head' only up to the daemon. This includes the
         * outer IP header, PIM header, PIM-Register header and the
         * inner IP header.
         * XXX: the outer IP header pkt size of a Register is not adjust to
         * reflect the fact that the inner multicast data is truncated.
         */
        /*
         * Currently, pim_input() is always called holding softnet_lock
         * by ipintr()(!NET_MPSAFE) or PR_INPUT_WRAP()(NET_MPSAFE).
         */
        KASSERT(mutex_owned(softnet_lock));
        rip_input(m, iphlen, proto);

        return;
}
#endif /* PIM */