No empty .Rs/.Re

[netbsd-mini2440.git] / sys / netinet / if_arp.c

/*      $NetBSD: if_arp.c,v 1.148 2009/11/03 00:57:42 christos Exp $    */

/*-
 * Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Public Access Networks Corporation ("Panix").  It was developed under
 * contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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.
 *
 *      @(#)if_ether.c  8.2 (Berkeley) 9/26/94
 */

/*
 * Ethernet address resolution protocol.
 * TODO:
 *      add "inuse/lock" bit (or ref. count) along with valid bit
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.148 2009/11/03 00:57:42 christos Exp $");

#include "opt_ddb.h"
#include "opt_inet.h"

#ifdef INET

#include "bridge.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/timetc.h>
#include <sys/kernel.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/syslog.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/sysctl.h>
#include <sys/socketvar.h>
#include <sys/percpu.h>

#include <net/ethertypes.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_token.h>
#include <net/if_types.h>
#include <net/if_ether.h>
#include <net/route.h>
#include <net/net_stats.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/if_inarp.h>

#include "arcnet.h"
#if NARCNET > 0
#include <net/if_arc.h>
#endif
#include "fddi.h"
#if NFDDI > 0
#include <net/if_fddi.h>
#endif
#include "token.h"
#include "carp.h"
#if NCARP > 0
#include <netinet/ip_carp.h>
#endif

#define SIN(s) ((struct sockaddr_in *)s)
#define SRP(s) ((struct sockaddr_inarp *)s)

/*
 * ARP trailer negotiation.  Trailer protocol is not IP specific,
 * but ARP request/response use IP addresses.
 */
#define ETHERTYPE_IPTRAILERS ETHERTYPE_TRAIL

/* timer values */
int     arpt_prune = (5*60*1);  /* walk list every 5 minutes */
int     arpt_keep = (20*60);    /* once resolved, good for 20 more minutes */
int     arpt_down = 20;         /* once declared down, don't send for 20 secs */
int     arpt_refresh = (5*60);  /* time left before refreshing */
#define rt_expire rt_rmx.rmx_expire
#define rt_pksent rt_rmx.rmx_pksent

static  struct sockaddr *arp_setgate(struct rtentry *, struct sockaddr *,
            const struct sockaddr *);
static  void arptfree(struct llinfo_arp *);
static  void arptimer(void *);
static  struct llinfo_arp *arplookup1(struct mbuf *, const struct in_addr *,
                                      int, int, struct rtentry *);
static  struct llinfo_arp *arplookup(struct mbuf *, const struct in_addr *,
                                          int, int);
static  void in_arpinput(struct mbuf *);

LIST_HEAD(, llinfo_arp) llinfo_arp;
struct  ifqueue arpintrq = {
        .ifq_head = NULL,
        .ifq_tail = NULL,
        .ifq_len = 0,
        .ifq_maxlen = 50,
        .ifq_drops = 0,
};
int     arp_inuse, arp_allocated, arp_intimer;
int     arp_maxtries = 5;
int     useloopback = 1;        /* use loopback interface for local traffic */
int     arpinit_done = 0;

static percpu_t *arpstat_percpu;

#define ARP_STAT_GETREF()       _NET_STAT_GETREF(arpstat_percpu)
#define ARP_STAT_PUTREF()       _NET_STAT_PUTREF(arpstat_percpu)

#define ARP_STATINC(x)          _NET_STATINC(arpstat_percpu, x)
#define ARP_STATADD(x, v)       _NET_STATADD(arpstat_percpu, x, v)

struct  callout arptimer_ch;

/* revarp state */
struct  in_addr myip, srv_ip;
int     myip_initialized = 0;
int     revarp_in_progress = 0;
struct  ifnet *myip_ifp = NULL;

#ifdef DDB
static void db_print_sa(const struct sockaddr *);
static void db_print_ifa(struct ifaddr *);
static void db_print_llinfo(void *);
static int db_show_rtentry(struct rtentry *, void *);
#endif

/*
 * this should be elsewhere.
 */

static char *
lla_snprintf(u_int8_t *, int);

static char *
lla_snprintf(u_int8_t *adrp, int len)
{
#define NUMBUFS 3
        static char buf[NUMBUFS][16*3];
        static int bnum = 0;

        int i;
        char *p;

        p = buf[bnum];

        *p++ = hexdigits[(*adrp)>>4];
        *p++ = hexdigits[(*adrp++)&0xf];

        for (i=1; i<len && i<16; i++) {
                *p++ = ':';
                *p++ = hexdigits[(*adrp)>>4];
                *p++ = hexdigits[(*adrp++)&0xf];
        }

        *p = 0;
        p = buf[bnum];
        bnum = (bnum + 1) % NUMBUFS;
        return p;
}

DOMAIN_DEFINE(arpdomain);       /* forward declare and add to link set */

const struct protosw arpsw[] = {
        { .pr_type = 0,
          .pr_domain = &arpdomain,
          .pr_protocol = 0,
          .pr_flags = 0,
          .pr_input = 0,
          .pr_output = 0,
          .pr_ctlinput = 0,
          .pr_ctloutput = 0,
          .pr_usrreq =  0,
          .pr_init = arp_init,
          .pr_fasttimo = 0,
          .pr_slowtimo = 0,
          .pr_drain = arp_drain,
        }
};


struct domain arpdomain = {
        .dom_family = PF_ARP,
        .dom_name = "arp",
        .dom_protosw = arpsw,
        .dom_protoswNPROTOSW = &arpsw[__arraycount(arpsw)],
};

/*
 * ARP table locking.
 *
 * to prevent lossage vs. the arp_drain routine (which may be called at
 * any time, including in a device driver context), we do two things:
 *
 * 1) manipulation of la->la_hold is done at splnet() (for all of
 * about two instructions).
 *
 * 2) manipulation of the arp table's linked list is done under the
 * protection of the ARP_LOCK; if arp_drain() or arptimer is called
 * while the arp table is locked, we punt and try again later.
 */

static int      arp_locked;
static inline int arp_lock_try(int);
static inline void arp_unlock(void);

static inline int
arp_lock_try(int recurse)
{
        int s;

        /*
         * Use splvm() -- we're blocking things that would cause
         * mbuf allocation.
         */
        s = splvm();
        if (!recurse && arp_locked) {
                splx(s);
                return 0;
        }
        arp_locked++;
        splx(s);
        return 1;
}

static inline void
arp_unlock(void)
{
        int s;

        s = splvm();
        arp_locked--;
        splx(s);
}

#ifdef DIAGNOSTIC
#define ARP_LOCK(recurse)                                               \
do {                                                                    \
        if (arp_lock_try(recurse) == 0) {                               \
                printf("%s:%d: arp already locked\n", __FILE__, __LINE__); \
                panic("arp_lock");                                      \
        }                                                               \
} while (/*CONSTCOND*/ 0)
#define ARP_LOCK_CHECK()                                                \
do {                                                                    \
        if (arp_locked == 0) {                                          \
                printf("%s:%d: arp lock not held\n", __FILE__, __LINE__); \
                panic("arp lock check");                                \
        }                                                               \
} while (/*CONSTCOND*/ 0)
#else
#define ARP_LOCK(x)             (void) arp_lock_try(x)
#define ARP_LOCK_CHECK()        /* nothing */
#endif

#define ARP_UNLOCK()            arp_unlock()

static void sysctl_net_inet_arp_setup(struct sysctllog **);

void
arp_init(void)
{

        sysctl_net_inet_arp_setup(NULL);
        arpstat_percpu = percpu_alloc(sizeof(uint64_t) * ARP_NSTATS);
}

/*
 * ARP protocol drain routine.  Called when memory is in short supply.
 * Called at splvm();  don't acquire softnet_lock as can be called from
 * hardware interrupt handlers.
 */
void
arp_drain(void)
{
        struct llinfo_arp *la, *nla;
        int count = 0;
        struct mbuf *mold;

        KERNEL_LOCK(1, NULL);

        if (arp_lock_try(0) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
                return;
        }

        for (la = LIST_FIRST(&llinfo_arp); la != NULL; la = nla) {
                nla = LIST_NEXT(la, la_list);

                mold = la->la_hold;
                la->la_hold = 0;

                if (mold) {
                        m_freem(mold);
                        count++;
                }
        }
        ARP_UNLOCK();
        ARP_STATADD(ARP_STAT_DFRDROPPED, count);
        KERNEL_UNLOCK_ONE(NULL);
}


/*
 * Timeout routine.  Age arp_tab entries periodically.
 */
/* ARGSUSED */
static void
arptimer(void *arg)
{
        struct llinfo_arp *la, *nla;

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);

        if (arp_lock_try(0) == 0) {
                /* get it later.. */
                KERNEL_UNLOCK_ONE(NULL);
                mutex_exit(softnet_lock);
                return;
        }

        callout_reset(&arptimer_ch, arpt_prune * hz, arptimer, NULL);
        for (la = LIST_FIRST(&llinfo_arp); la != NULL; la = nla) {
                struct rtentry *rt = la->la_rt;

                nla = LIST_NEXT(la, la_list);
                if (rt->rt_expire == 0)
                        continue;
                if ((rt->rt_expire - time_second) < arpt_refresh &&
                    rt->rt_pksent > (time_second - arpt_keep)) {
                        /*
                         * If the entry has been used during since last
                         * refresh, try to renew it before deleting.
                         */
                        arprequest(rt->rt_ifp,
                            &satocsin(rt->rt_ifa->ifa_addr)->sin_addr,
                            &satocsin(rt_getkey(rt))->sin_addr,
                            CLLADDR(rt->rt_ifp->if_sadl));
                } else if (rt->rt_expire <= time_second)
                        arptfree(la); /* timer has expired; clear */
        }

        ARP_UNLOCK();

        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

/*
 * We set the gateway for RTF_CLONING routes to a "prototype"
 * link-layer sockaddr whose interface type (if_type) and interface
 * index (if_index) fields are prepared.
 */
static struct sockaddr *
arp_setgate(struct rtentry *rt, struct sockaddr *gate,
    const struct sockaddr *netmask)
{
        const struct ifnet *ifp = rt->rt_ifp;
        uint8_t namelen = strlen(ifp->if_xname);
        uint8_t addrlen = ifp->if_addrlen;

        /*
         * XXX: If this is a manually added route to interface
         * such as older version of routed or gated might provide,
         * restore cloning bit.
         */
        if ((rt->rt_flags & RTF_HOST) == 0 && netmask != NULL &&
            satocsin(netmask)->sin_addr.s_addr != 0xffffffff)
                rt->rt_flags |= RTF_CLONING;
        if (rt->rt_flags & RTF_CLONING) {
                union {
                        struct sockaddr sa;
                        struct sockaddr_storage ss;
                        struct sockaddr_dl sdl;
                } u;
                /*
                 * Case 1: This route should come from a route to iface.
                 */
                sockaddr_dl_init(&u.sdl, sizeof(u.ss),
                    ifp->if_index, ifp->if_type, NULL, namelen, NULL, addrlen);
                rt_setgate(rt, &u.sa);
                gate = rt->rt_gateway;
        }
        return gate;
}

/*
 * Parallel to llc_rtrequest.
 */
void
arp_rtrequest(int req, struct rtentry *rt, const struct rt_addrinfo *info)
{
        struct sockaddr *gate = rt->rt_gateway;
        struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
        size_t allocsize;
        struct mbuf *mold;
        int s;
        struct in_ifaddr *ia;
        struct ifaddr *ifa;
        struct ifnet *ifp = rt->rt_ifp;

        if (!arpinit_done) {
                arpinit_done = 1;
                /*
                 * We generate expiration times from time_second
                 * so avoid accidentally creating permanent routes.
                 */
                if (time_second == 0) {
                        struct timespec ts;
                        ts.tv_sec = 1;
                        ts.tv_nsec = 0;
                        tc_setclock(&ts);
                }
                callout_init(&arptimer_ch, CALLOUT_MPSAFE);
                callout_reset(&arptimer_ch, hz, arptimer, NULL);
        }

        if (req == RTM_LLINFO_UPD) {
                struct in_addr *in;

                if ((ifa = info->rti_ifa) == NULL)
                        return;

                in = &ifatoia(ifa)->ia_addr.sin_addr;

                arprequest(ifa->ifa_ifp, in, in,
                    CLLADDR(ifa->ifa_ifp->if_sadl));
                return;
        }

        if ((rt->rt_flags & RTF_GATEWAY) != 0) {
                if (req != RTM_ADD)
                        return;

                /*
                 * linklayers with particular link MTU limitation.
                 */
                switch(ifp->if_type) {
#if NFDDI > 0
                case IFT_FDDI:
                        if (ifp->if_mtu > FDDIIPMTU)
                                rt->rt_rmx.rmx_mtu = FDDIIPMTU;
                        break;
#endif
#if NARC > 0
                case IFT_ARCNET:
                    {
                        int arcipifmtu;

                        if (ifp->if_flags & IFF_LINK0)
                                arcipifmtu = arc_ipmtu;
                        else
                                arcipifmtu = ARCMTU;
                        if (ifp->if_mtu > arcipifmtu)
                                rt->rt_rmx.rmx_mtu = arcipifmtu;
                        break;
                    }
#endif
                }
                return;
        }

        ARP_LOCK(1);            /* we may already be locked here. */

        switch (req) {
        case RTM_SETGATE:
                gate = arp_setgate(rt, gate, info->rti_info[RTAX_NETMASK]);
                break;
        case RTM_ADD:
                gate = arp_setgate(rt, gate, info->rti_info[RTAX_NETMASK]);
                if (rt->rt_flags & RTF_CLONING) {
                        /*
                         * Give this route an expiration time, even though
                         * it's a "permanent" route, so that routes cloned
                         * from it do not need their expiration time set.
                         */
                        rt->rt_expire = time_second;
                        /*
                         * linklayers with particular link MTU limitation.
                         */
                        switch (ifp->if_type) {
#if NFDDI > 0
                        case IFT_FDDI:
                                if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0 &&
                                    (rt->rt_rmx.rmx_mtu > FDDIIPMTU ||
                                     (rt->rt_rmx.rmx_mtu == 0 &&
                                      ifp->if_mtu > FDDIIPMTU)))
                                        rt->rt_rmx.rmx_mtu = FDDIIPMTU;
                                break;
#endif
#if NARC > 0
                        case IFT_ARCNET:
                            {
                                int arcipifmtu;
                                if (ifp->if_flags & IFF_LINK0)
                                        arcipifmtu = arc_ipmtu;
                                else
                                        arcipifmtu = ARCMTU;

                                if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0 &&
                                    (rt->rt_rmx.rmx_mtu > arcipifmtu ||
                                     (rt->rt_rmx.rmx_mtu == 0 &&
                                      ifp->if_mtu > arcipifmtu)))
                                        rt->rt_rmx.rmx_mtu = arcipifmtu;
                                break;
                            }
#endif
                        }
                        break;
                }
                /* Announce a new entry if requested. */
                if (rt->rt_flags & RTF_ANNOUNCE) {
                        arprequest(ifp,
                            &satocsin(rt_getkey(rt))->sin_addr,
                            &satocsin(rt_getkey(rt))->sin_addr,
                            CLLADDR(satocsdl(gate)));
                }
                /*FALLTHROUGH*/
        case RTM_RESOLVE:
                if (gate->sa_family != AF_LINK ||
                    gate->sa_len < sockaddr_dl_measure(0, ifp->if_addrlen)) {
                        log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
                        break;
                }
                satosdl(gate)->sdl_type = ifp->if_type;
                satosdl(gate)->sdl_index = ifp->if_index;
                if (la != NULL)
                        break; /* This happens on a route change */
                /*
                 * Case 2:  This route may come from cloning, or a manual route
                 * add with a LL address.
                 */
                switch (ifp->if_type) {
#if NTOKEN > 0
                case IFT_ISO88025:
                        allocsize = sizeof(*la) + sizeof(struct token_rif);
                        break;
#endif /* NTOKEN > 0 */
                default:
                        allocsize = sizeof(*la);
                }
                R_Malloc(la, struct llinfo_arp *, allocsize);
                rt->rt_llinfo = (void *)la;
                if (la == NULL) {
                        log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
                        break;
                }
                arp_inuse++, arp_allocated++;
                memset(la, 0, allocsize);
                la->la_rt = rt;
                rt->rt_flags |= RTF_LLINFO;
                LIST_INSERT_HEAD(&llinfo_arp, la, la_list);

                INADDR_TO_IA(satocsin(rt_getkey(rt))->sin_addr, ia);
                while (ia && ia->ia_ifp != ifp)
                        NEXT_IA_WITH_SAME_ADDR(ia);
                if (ia) {
                        /*
                         * This test used to be
                         *      if (lo0ifp->if_flags & IFF_UP)
                         * It allowed local traffic to be forced through
                         * the hardware by configuring the loopback down.
                         * However, it causes problems during network
                         * configuration for boards that can't receive
                         * packets they send.  It is now necessary to clear
                         * "useloopback" and remove the route to force
                         * traffic out to the hardware.
                         *
                         * In 4.4BSD, the above "if" statement checked
                         * rt->rt_ifa against rt_getkey(rt).  It was changed
                         * to the current form so that we can provide a
                         * better support for multiple IPv4 addresses on a
                         * interface.
                         */
                        rt->rt_expire = 0;
                        if (sockaddr_dl_init(satosdl(gate), gate->sa_len,
                            ifp->if_index, ifp->if_type, NULL, 0,
                            CLLADDR(ifp->if_sadl), ifp->if_addrlen) == NULL) {
                                panic("%s(%s): sockaddr_dl_init cannot fail",
                                    __func__, ifp->if_xname);
                        }
                        if (useloopback)
                                ifp = rt->rt_ifp = lo0ifp;
                        /*
                         * make sure to set rt->rt_ifa to the interface
                         * address we are using, otherwise we will have trouble
                         * with source address selection.
                         */
                        ifa = &ia->ia_ifa;
                        if (ifa != rt->rt_ifa)
                                rt_replace_ifa(rt, ifa);
                }
                break;

        case RTM_DELETE:
                if (la == NULL)
                        break;
                arp_inuse--;
                LIST_REMOVE(la, la_list);
                rt->rt_llinfo = NULL;
                rt->rt_flags &= ~RTF_LLINFO;

                s = splnet();
                mold = la->la_hold;
                la->la_hold = 0;
                splx(s);

                if (mold)
                        m_freem(mold);

                Free((void *)la);
        }
        ARP_UNLOCK();
}

/*
 * Broadcast an ARP request. Caller specifies:
 *      - arp header source ip address
 *      - arp header target ip address
 *      - arp header source ethernet address
 */
void
arprequest(struct ifnet *ifp,
    const struct in_addr *sip, const struct in_addr *tip,
    const u_int8_t *enaddr)
{
        struct mbuf *m;
        struct arphdr *ah;
        struct sockaddr sa;
        uint64_t *arps;

        if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
                return;
        MCLAIM(m, &arpdomain.dom_mowner);
        switch (ifp->if_type) {
        case IFT_IEEE1394:
                m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
                    ifp->if_addrlen;
                break;
        default:
                m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
                    2 * ifp->if_addrlen;
                break;
        }
        m->m_pkthdr.len = m->m_len;
        MH_ALIGN(m, m->m_len);
        ah = mtod(m, struct arphdr *);
        memset(ah, 0, m->m_len);
        switch (ifp->if_type) {
        case IFT_IEEE1394:      /* RFC2734 */
                /* fill it now for ar_tpa computation */
                ah->ar_hrd = htons(ARPHRD_IEEE1394);
                break;
        default:
                /* ifp->if_output will fill ar_hrd */
                break;
        }
        ah->ar_pro = htons(ETHERTYPE_IP);
        ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
        ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
        ah->ar_op = htons(ARPOP_REQUEST);
        memcpy(ar_sha(ah), enaddr, ah->ar_hln);
        memcpy(ar_spa(ah), sip, ah->ar_pln);
        memcpy(ar_tpa(ah), tip, ah->ar_pln);
        sa.sa_family = AF_ARP;
        sa.sa_len = 2;
        m->m_flags |= M_BCAST;
        arps = ARP_STAT_GETREF();
        arps[ARP_STAT_SNDTOTAL]++;
        arps[ARP_STAT_SENDREQUEST]++;
        ARP_STAT_PUTREF();
        (*ifp->if_output)(ifp, m, &sa, NULL);
}

/*
 * Resolve an IP address into an ethernet address.  If success,
 * desten is filled in.  If there is no entry in arptab,
 * set one up and broadcast a request for the IP address.
 * Hold onto this mbuf and resend it once the address
 * is finally resolved.  A return value of 1 indicates
 * that desten has been filled in and the packet should be sent
 * normally; a 0 return indicates that the packet has been
 * taken over here, either now or for later transmission.
 */
int
arpresolve(struct ifnet *ifp, struct rtentry *rt, struct mbuf *m,
    const struct sockaddr *dst, u_char *desten)
{
        struct llinfo_arp *la;
        const struct sockaddr_dl *sdl;
        struct mbuf *mold;
        int s;

        if ((la = arplookup1(m, &satocsin(dst)->sin_addr, 1, 0, rt)) != NULL)
                rt = la->la_rt;

        if (la == NULL || rt == NULL) {
                ARP_STATINC(ARP_STAT_ALLOCFAIL);
                log(LOG_DEBUG,
                    "arpresolve: can't allocate llinfo on %s for %s\n",
                    ifp->if_xname, in_fmtaddr(satocsin(dst)->sin_addr));
                m_freem(m);
                return 0;
        }
        sdl = satocsdl(rt->rt_gateway);
        /*
         * Check the address family and length is valid, the address
         * is resolved; otherwise, try to resolve.
         */
        if ((rt->rt_expire == 0 || rt->rt_expire > time_second) &&
            sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
                memcpy(desten, CLLADDR(sdl),
                    min(sdl->sdl_alen, ifp->if_addrlen));
                rt->rt_pksent = time_second; /* Time for last pkt sent */
                return 1;
        }
        /*
         * There is an arptab entry, but no ethernet address
         * response yet.  Replace the held mbuf with this
         * latest one.
         */

        ARP_STATINC(ARP_STAT_DFRTOTAL);
        s = splnet();
        mold = la->la_hold;
        la->la_hold = m;
        splx(s);

        if (mold) {
                ARP_STATINC(ARP_STAT_DFRDROPPED);
                m_freem(mold);
        }

        /*
         * Re-send the ARP request when appropriate.
         */
#ifdef  DIAGNOSTIC
        if (rt->rt_expire == 0) {
                /* This should never happen. (Should it? -gwr) */
                printf("arpresolve: unresolved and rt_expire == 0\n");
                /* Set expiration time to now (expired). */
                rt->rt_expire = time_second;
        }
#endif
        if (rt->rt_expire) {
                rt->rt_flags &= ~RTF_REJECT;
                if (la->la_asked == 0 || rt->rt_expire != time_second) {
                        rt->rt_expire = time_second;
                        if (la->la_asked++ < arp_maxtries) {
                                arprequest(ifp,
                                    &satocsin(rt->rt_ifa->ifa_addr)->sin_addr,
                                    &satocsin(dst)->sin_addr,
#if NCARP > 0
                                    (rt->rt_ifp->if_type == IFT_CARP) ?
                                    CLLADDR(rt->rt_ifp->if_sadl):
#endif
                                    CLLADDR(ifp->if_sadl));
                        } else {
                                rt->rt_flags |= RTF_REJECT;
                                rt->rt_expire += arpt_down;
                                la->la_asked = 0;
                        }
                }
        }
        return 0;
}

/*
 * Common length and type checks are done here,
 * then the protocol-specific routine is called.
 */
void
arpintr(void)
{
        struct mbuf *m;
        struct arphdr *ar;
        int s;
        int arplen;

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);
        while (arpintrq.ifq_head) {
                s = splnet();
                IF_DEQUEUE(&arpintrq, m);
                splx(s);
                if (m == 0 || (m->m_flags & M_PKTHDR) == 0)
                        panic("arpintr");

                MCLAIM(m, &arpdomain.dom_mowner);
                ARP_STATINC(ARP_STAT_RCVTOTAL);

                /*
                 * First, make sure we have at least struct arphdr.
                 */
                if (m->m_len < sizeof(struct arphdr) ||
                    (ar = mtod(m, struct arphdr *)) == NULL)
                        goto badlen;

                switch (m->m_pkthdr.rcvif->if_type) {
                case IFT_IEEE1394:
                        arplen = sizeof(struct arphdr) +
                            ar->ar_hln + 2 * ar->ar_pln;
                        break;
                default:
                        arplen = sizeof(struct arphdr) +
                            2 * ar->ar_hln + 2 * ar->ar_pln;
                        break;
                }

                if (/* XXX ntohs(ar->ar_hrd) == ARPHRD_ETHER && */
                    m->m_len >= arplen)
                        switch (ntohs(ar->ar_pro)) {
                        case ETHERTYPE_IP:
                        case ETHERTYPE_IPTRAILERS:
                                in_arpinput(m);
                                continue;
                        default:
                                ARP_STATINC(ARP_STAT_RCVBADPROTO);
                        }
                else {
badlen:
                        ARP_STATINC(ARP_STAT_RCVBADLEN);
                }
                m_freem(m);
        }
        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

/*
 * ARP for Internet protocols on 10 Mb/s Ethernet.
 * Algorithm is that given in RFC 826.
 * In addition, a sanity check is performed on the sender
 * protocol address, to catch impersonators.
 * We no longer handle negotiations for use of trailer protocol:
 * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
 * along with IP replies if we wanted trailers sent to us,
 * and also sent them in response to IP replies.
 * This allowed either end to announce the desire to receive
 * trailer packets.
 * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
 * but formerly didn't normally send requests.
 */
static void
in_arpinput(struct mbuf *m)
{
        struct arphdr *ah;
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        struct llinfo_arp *la = NULL;
        struct rtentry  *rt;
        struct in_ifaddr *ia;
#if NBRIDGE > 0
        struct in_ifaddr *bridge_ia = NULL;
#endif
#if NCARP > 0
        u_int32_t count = 0, index = 0;
#endif
        struct sockaddr_dl *sdl;
        struct sockaddr sa;
        struct in_addr isaddr, itaddr, myaddr;
        int op;
        struct mbuf *mold;
        void *tha;
        int s;
        uint64_t *arps;

        if (__predict_false(m_makewritable(&m, 0, m->m_pkthdr.len, M_DONTWAIT)))
                goto out;
        ah = mtod(m, struct arphdr *);
        op = ntohs(ah->ar_op);

        /*
         * Fix up ah->ar_hrd if necessary, before using ar_tha() or
         * ar_tpa().
         */
        switch (ifp->if_type) {
        case IFT_IEEE1394:
                if (ntohs(ah->ar_hrd) == ARPHRD_IEEE1394)
                        ;
                else {
                        /* XXX this is to make sure we compute ar_tha right */
                        /* XXX check ar_hrd more strictly? */
                        ah->ar_hrd = htons(ARPHRD_IEEE1394);
                }
                break;
        default:
                /* XXX check ar_hrd? */
                break;
        }

        memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
        memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));

        if (m->m_flags & (M_BCAST|M_MCAST))
                ARP_STATINC(ARP_STAT_RCVMCAST);

        /*
         * If the target IP address is zero, ignore the packet.
         * This prevents the code below from tring to answer
         * when we are using IP address zero (booting).
         */
        if (in_nullhost(itaddr)) {
                ARP_STATINC(ARP_STAT_RCVZEROTPA);
                goto out;
        }


        /*
         * Search for a matching interface address
         * or any address on the interface to use
         * as a dummy address in the rest of this function
         */
        
        INADDR_TO_IA(itaddr, ia);
        while (ia != NULL) {
#if NCARP > 0
                if (ia->ia_ifp->if_type == IFT_CARP &&
                    ((ia->ia_ifp->if_flags & (IFF_UP|IFF_RUNNING)) ==
                    (IFF_UP|IFF_RUNNING))) {
                        index++;
                        if (ia->ia_ifp == m->m_pkthdr.rcvif &&
                            carp_iamatch(ia, ar_sha(ah),
                            &count, index)) {
                                break;
                                }
                } else
#endif
                            if (ia->ia_ifp == m->m_pkthdr.rcvif)
                                break;
#if NBRIDGE > 0
                /*
                 * If the interface we received the packet on
                 * is part of a bridge, check to see if we need
                 * to "bridge" the packet to ourselves at this
                 * layer.  Note we still prefer a perfect match,
                 * but allow this weaker match if necessary.
                 */
                if (m->m_pkthdr.rcvif->if_bridge != NULL &&
                    m->m_pkthdr.rcvif->if_bridge == ia->ia_ifp->if_bridge)
                        bridge_ia = ia;
#endif /* NBRIDGE > 0 */

                NEXT_IA_WITH_SAME_ADDR(ia);
        }

#if NBRIDGE > 0
        if (ia == NULL && bridge_ia != NULL) {
                ia = bridge_ia;
                ifp = bridge_ia->ia_ifp;
        }
#endif

        if (ia == NULL) {
                INADDR_TO_IA(isaddr, ia);
                while ((ia != NULL) && ia->ia_ifp != m->m_pkthdr.rcvif)
                        NEXT_IA_WITH_SAME_ADDR(ia);

                if (ia == NULL) {
                        IFP_TO_IA(ifp, ia);
                        if (ia == NULL) {
                                ARP_STATINC(ARP_STAT_RCVNOINT);
                                goto out;
                        }
                }
        }

        myaddr = ia->ia_addr.sin_addr;

        /* XXX checks for bridge case? */
        if (!memcmp(ar_sha(ah), CLLADDR(ifp->if_sadl), ifp->if_addrlen)) {
                ARP_STATINC(ARP_STAT_RCVLOCALSHA);
                goto out;       /* it's from me, ignore it. */
        }

        /* XXX checks for bridge case? */
        if (!memcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
                ARP_STATINC(ARP_STAT_RCVBCASTSHA);
                log(LOG_ERR,
                    "%s: arp: link address is broadcast for IP address %s!\n",
                    ifp->if_xname, in_fmtaddr(isaddr));
                goto out;
        }

        /*
         * If the source IP address is zero, this is an RFC 5227 ARP probe
         */
        if (in_nullhost(isaddr)) {
                ARP_STATINC(ARP_STAT_RCVZEROSPA);
                goto reply;
        }

        if (in_hosteq(isaddr, myaddr)) {
                ARP_STATINC(ARP_STAT_RCVLOCALSPA);
                log(LOG_ERR,
                   "duplicate IP address %s sent from link address %s\n",
                   in_fmtaddr(isaddr), lla_snprintf(ar_sha(ah), ah->ar_hln));
                itaddr = myaddr;
                goto reply;
        }
        la = arplookup(m, &isaddr, in_hosteq(itaddr, myaddr), 0);
        if (la != NULL && (rt = la->la_rt) && (sdl = satosdl(rt->rt_gateway))) {
                if (sdl->sdl_alen &&
                    memcmp(ar_sha(ah), CLLADDR(sdl), sdl->sdl_alen)) {
                        if (rt->rt_flags & RTF_STATIC) {
                                ARP_STATINC(ARP_STAT_RCVOVERPERM);
                                log(LOG_INFO,
                                    "%s tried to overwrite permanent arp info"
                                    " for %s\n",
                                    lla_snprintf(ar_sha(ah), ah->ar_hln),
                                    in_fmtaddr(isaddr));
                                goto out;
                        } else if (rt->rt_ifp != ifp) {
                                ARP_STATINC(ARP_STAT_RCVOVERINT);
                                log(LOG_INFO,
                                    "%s on %s tried to overwrite "
                                    "arp info for %s on %s\n",
                                    lla_snprintf(ar_sha(ah), ah->ar_hln),
                                    ifp->if_xname, in_fmtaddr(isaddr),
                                    rt->rt_ifp->if_xname);
                                    goto out;
                        } else {
                                ARP_STATINC(ARP_STAT_RCVOVER);
                                log(LOG_INFO,
                                    "arp info overwritten for %s by %s\n",
                                    in_fmtaddr(isaddr),
                                    lla_snprintf(ar_sha(ah), ah->ar_hln));
                        }
                }
                /*
                 * sanity check for the address length.
                 * XXX this does not work for protocols with variable address
                 * length. -is
                 */
                if (sdl->sdl_alen &&
                    sdl->sdl_alen != ah->ar_hln) {
                        ARP_STATINC(ARP_STAT_RCVLENCHG);
                        log(LOG_WARNING,
                            "arp from %s: new addr len %d, was %d\n",
                            in_fmtaddr(isaddr), ah->ar_hln, sdl->sdl_alen);
                }
                if (ifp->if_addrlen != ah->ar_hln) {
                        ARP_STATINC(ARP_STAT_RCVBADLEN);
                        log(LOG_WARNING,
                            "arp from %s: addr len: new %d, i/f %d (ignored)\n",
                            in_fmtaddr(isaddr), ah->ar_hln,
                            ifp->if_addrlen);
                        goto reply;
                }
#if NTOKEN > 0
                /*
                 * XXX uses m_data and assumes the complete answer including
                 * XXX token-ring headers is in the same buf
                 */
                if (ifp->if_type == IFT_ISO88025) {
                        struct token_header *trh;

                        trh = (struct token_header *)M_TRHSTART(m);
                        if (trh->token_shost[0] & TOKEN_RI_PRESENT) {
                                struct token_rif        *rif;
                                size_t  riflen;

                                rif = TOKEN_RIF(trh);
                                riflen = (ntohs(rif->tr_rcf) &
                                    TOKEN_RCF_LEN_MASK) >> 8;

                                if (riflen > 2 &&
                                    riflen < sizeof(struct token_rif) &&
                                    (riflen & 1) == 0) {
                                        rif->tr_rcf ^= htons(TOKEN_RCF_DIRECTION);
                                        rif->tr_rcf &= htons(~TOKEN_RCF_BROADCAST_MASK);
                                        memcpy(TOKEN_RIF(la), rif, riflen);
                                }
                        }
                }
#endif /* NTOKEN > 0 */
                (void)sockaddr_dl_setaddr(sdl, sdl->sdl_len, ar_sha(ah),
                    ah->ar_hln);
                if (rt->rt_expire)
                        rt->rt_expire = time_second + arpt_keep;
                rt->rt_flags &= ~RTF_REJECT;
                la->la_asked = 0;

                s = splnet();
                mold = la->la_hold;
                la->la_hold = 0;
                splx(s);

                if (mold) {
                        ARP_STATINC(ARP_STAT_DFRSENT);
                        (*ifp->if_output)(ifp, mold, rt_getkey(rt), rt);
                }
        }
reply:
        if (op != ARPOP_REQUEST) {
                if (op == ARPOP_REPLY)
                        ARP_STATINC(ARP_STAT_RCVREPLY);
        out:
                m_freem(m);
                return;
        }
        ARP_STATINC(ARP_STAT_RCVREQUEST);
        if (in_hosteq(itaddr, myaddr)) {
                /* I am the target */
                tha = ar_tha(ah);
                if (tha)
                        memcpy(tha, ar_sha(ah), ah->ar_hln);
                memcpy(ar_sha(ah), CLLADDR(ifp->if_sadl), ah->ar_hln);
        } else {
                la = arplookup(m, &itaddr, 0, SIN_PROXY);
                if (la == NULL)
                        goto out;
                rt = la->la_rt;
                if (rt->rt_ifp->if_type == IFT_CARP &&
                    m->m_pkthdr.rcvif->if_type != IFT_CARP)
                        goto out;
                tha = ar_tha(ah);
                if (tha)
                        memcpy(tha, ar_sha(ah), ah->ar_hln);
                sdl = satosdl(rt->rt_gateway);
                memcpy(ar_sha(ah), CLLADDR(sdl), ah->ar_hln);
        }

        memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
        memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
        ah->ar_op = htons(ARPOP_REPLY);
        ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
        switch (ifp->if_type) {
        case IFT_IEEE1394:
                /*
                 * ieee1394 arp reply is broadcast
                 */
                m->m_flags &= ~M_MCAST;
                m->m_flags |= M_BCAST;
                m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + ah->ar_hln;
                break;

        default:
                m->m_flags &= ~(M_BCAST|M_MCAST); /* never reply by broadcast */
                m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
                break;
        }
        m->m_pkthdr.len = m->m_len;
        sa.sa_family = AF_ARP;
        sa.sa_len = 2;
        arps = ARP_STAT_GETREF();
        arps[ARP_STAT_SNDTOTAL]++;
        arps[ARP_STAT_SNDREPLY]++;
        ARP_STAT_PUTREF();
        (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
        return;
}

/*
 * Free an arp entry.
 */
static void arptfree(struct llinfo_arp *la)
{
        struct rtentry *rt = la->la_rt;
        struct sockaddr_dl *sdl;

        ARP_LOCK_CHECK();

        if (rt == NULL)
                panic("arptfree");
        if (rt->rt_refcnt > 0 && (sdl = satosdl(rt->rt_gateway)) &&
            sdl->sdl_family == AF_LINK) {
                sdl->sdl_alen = 0;
                la->la_asked = 0;
                rt->rt_flags &= ~RTF_REJECT;
                return;
        }
        rtrequest(RTM_DELETE, rt_getkey(rt), NULL, rt_mask(rt), 0, NULL);
}

static struct llinfo_arp *
arplookup(struct mbuf *m, const struct in_addr *addr, int create, int proxy)
{
        return arplookup1(m, addr, create, proxy, NULL);
}

/*
 * Lookup or enter a new address in arptab.
 */
static struct llinfo_arp *
arplookup1(struct mbuf *m, const struct in_addr *addr, int create, int proxy,
    struct rtentry *rt0)
{
        struct arphdr *ah;
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        struct rtentry *rt;
        struct sockaddr_inarp sin;
        const char *why = NULL;

        ah = mtod(m, struct arphdr *);
        if (rt0 == NULL) {
                memset(&sin, 0, sizeof(sin));
                sin.sin_len = sizeof(sin);
                sin.sin_family = AF_INET;
                sin.sin_addr = *addr;
                sin.sin_other = proxy ? SIN_PROXY : 0;
                rt = rtalloc1(sintosa(&sin), create);
                if (rt == NULL)
                        return NULL;
                rt->rt_refcnt--;
        } else
                rt = rt0;

#define IS_LLINFO(__rt)                                                   \
        (((__rt)->rt_flags & (RTF_GATEWAY | RTF_LLINFO)) == RTF_LLINFO && \
         (__rt)->rt_gateway->sa_family == AF_LINK)


        if (IS_LLINFO(rt))
                return (struct llinfo_arp *)rt->rt_llinfo;

        if (create) {
                if (rt->rt_flags & RTF_GATEWAY)
                        why = "host is not on local network";
                else if ((rt->rt_flags & RTF_LLINFO) == 0) {
                        ARP_STATINC(ARP_STAT_ALLOCFAIL);
                        why = "could not allocate llinfo";
                } else
                        why = "gateway route is not ours";
                log(LOG_DEBUG, "arplookup: unable to enter address"
                    " for %s@%s on %s (%s)\n",
                    in_fmtaddr(*addr), lla_snprintf(ar_sha(ah), ah->ar_hln),
                    (ifp) ? ifp->if_xname : "null", why);
                if (rt->rt_refcnt <= 0 && (rt->rt_flags & RTF_CLONED) != 0) {
                        rtrequest(RTM_DELETE, rt_getkey(rt),
                            rt->rt_gateway, rt_mask(rt), rt->rt_flags, NULL);
                }
        }
        return NULL;
}

int
arpioctl(u_long cmd, void *data)
{

        return EOPNOTSUPP;
}

void
arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
{
        struct in_addr *ip;

        /*
         * Warn the user if another station has this IP address,
         * but only if the interface IP address is not zero.
         */
        ip = &IA_SIN(ifa)->sin_addr;
        if (!in_nullhost(*ip))
                arprequest(ifp, ip, ip, CLLADDR(ifp->if_sadl));

        ifa->ifa_rtrequest = arp_rtrequest;
        ifa->ifa_flags |= RTF_CLONING;
}

/*
 * Called from 10 Mb/s Ethernet interrupt handlers
 * when ether packet type ETHERTYPE_REVARP
 * is received.  Common length and type checks are done here,
 * then the protocol-specific routine is called.
 */
void
revarpinput(struct mbuf *m)
{
        struct arphdr *ar;

        if (m->m_len < sizeof(struct arphdr))
                goto out;
        ar = mtod(m, struct arphdr *);
#if 0 /* XXX I don't think we need this... and it will prevent other LL */
        if (ntohs(ar->ar_hrd) != ARPHRD_ETHER)
                goto out;
#endif
        if (m->m_len < sizeof(struct arphdr) + 2 * (ar->ar_hln + ar->ar_pln))
                goto out;
        switch (ntohs(ar->ar_pro)) {
        case ETHERTYPE_IP:
        case ETHERTYPE_IPTRAILERS:
                in_revarpinput(m);
                return;

        default:
                break;
        }
out:
        m_freem(m);
}

/*
 * RARP for Internet protocols on 10 Mb/s Ethernet.
 * Algorithm is that given in RFC 903.
 * We are only using for bootstrap purposes to get an ip address for one of
 * our interfaces.  Thus we support no user-interface.
 *
 * Since the contents of the RARP reply are specific to the interface that
 * sent the request, this code must ensure that they are properly associated.
 *
 * Note: also supports ARP via RARP packets, per the RFC.
 */
void
in_revarpinput(struct mbuf *m)
{
        struct ifnet *ifp;
        struct arphdr *ah;
        void *tha;
        int op;

        ah = mtod(m, struct arphdr *);
        op = ntohs(ah->ar_op);

        switch (m->m_pkthdr.rcvif->if_type) {
        case IFT_IEEE1394:
                /* ARP without target hardware address is not supported */
                goto out;
        default:
                break;
        }

        switch (op) {
        case ARPOP_REQUEST:
        case ARPOP_REPLY:       /* per RFC */
                in_arpinput(m);
                return;
        case ARPOP_REVREPLY:
                break;
        case ARPOP_REVREQUEST:  /* handled by rarpd(8) */
        default:
                goto out;
        }
        if (!revarp_in_progress)
                goto out;
        ifp = m->m_pkthdr.rcvif;
        if (ifp != myip_ifp) /* !same interface */
                goto out;
        if (myip_initialized)
                goto wake;
        tha = ar_tha(ah);
        if (tha == NULL)
                goto out;
        if (memcmp(tha, CLLADDR(ifp->if_sadl), ifp->if_sadl->sdl_alen))
                goto out;
        memcpy(&srv_ip, ar_spa(ah), sizeof(srv_ip));
        memcpy(&myip, ar_tpa(ah), sizeof(myip));
        myip_initialized = 1;
wake:   /* Do wakeup every time in case it was missed. */
        wakeup((void *)&myip);

out:
        m_freem(m);
}

/*
 * Send a RARP request for the ip address of the specified interface.
 * The request should be RFC 903-compliant.
 */
void
revarprequest(struct ifnet *ifp)
{
        struct sockaddr sa;
        struct mbuf *m;
        struct arphdr *ah;
        void *tha;

        if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
                return;
        MCLAIM(m, &arpdomain.dom_mowner);
        m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
            2*ifp->if_addrlen;
        m->m_pkthdr.len = m->m_len;
        MH_ALIGN(m, m->m_len);
        ah = mtod(m, struct arphdr *);
        memset(ah, 0, m->m_len);
        ah->ar_pro = htons(ETHERTYPE_IP);
        ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
        ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
        ah->ar_op = htons(ARPOP_REVREQUEST);

        memcpy(ar_sha(ah), CLLADDR(ifp->if_sadl), ah->ar_hln);
        tha = ar_tha(ah);
        if (tha == NULL)
                return;
        memcpy(tha, CLLADDR(ifp->if_sadl), ah->ar_hln);

        sa.sa_family = AF_ARP;
        sa.sa_len = 2;
        m->m_flags |= M_BCAST;
        (*ifp->if_output)(ifp, m, &sa, NULL);

}

/*
 * RARP for the ip address of the specified interface, but also
 * save the ip address of the server that sent the answer.
 * Timeout if no response is received.
 */
int
revarpwhoarewe(struct ifnet *ifp, struct in_addr *serv_in,
    struct in_addr *clnt_in)
{
        int result, count = 20;

        myip_initialized = 0;
        myip_ifp = ifp;

        revarp_in_progress = 1;
        while (count--) {
                revarprequest(ifp);
                result = tsleep((void *)&myip, PSOCK, "revarp", hz/2);
                if (result != EWOULDBLOCK)
                        break;
        }
        revarp_in_progress = 0;

        if (!myip_initialized)
                return ENETUNREACH;

        memcpy(serv_in, &srv_ip, sizeof(*serv_in));
        memcpy(clnt_in, &myip, sizeof(*clnt_in));
        return 0;
}

\f

#ifdef DDB

#include <machine/db_machdep.h>
#include <ddb/db_interface.h>
#include <ddb/db_output.h>

static void
db_print_sa(const struct sockaddr *sa)
{
        int len;
        const u_char *p;

        if (sa == NULL) {
                db_printf("[NULL]");
                return;
        }

        p = (const u_char *)sa;
        len = sa->sa_len;
        db_printf("[");
        while (len > 0) {
                db_printf("%d", *p);
                p++; len--;
                if (len) db_printf(",");
        }
        db_printf("]\n");
}

static void
db_print_ifa(struct ifaddr *ifa)
{
        if (ifa == NULL)
                return;
        db_printf("  ifa_addr=");
        db_print_sa(ifa->ifa_addr);
        db_printf("  ifa_dsta=");
        db_print_sa(ifa->ifa_dstaddr);
        db_printf("  ifa_mask=");
        db_print_sa(ifa->ifa_netmask);
        db_printf("  flags=0x%x,refcnt=%d,metric=%d\n",
                          ifa->ifa_flags,
                          ifa->ifa_refcnt,
                          ifa->ifa_metric);
}

static void
db_print_llinfo(void *li)
{
        struct llinfo_arp *la;

        if (li == NULL)
                return;
        la = (struct llinfo_arp *)li;
        db_printf("  la_rt=%p la_hold=%p, la_asked=0x%lx\n",
                          la->la_rt, la->la_hold, la->la_asked);
}

/*
 * Function to pass to rt_walktree().
 * Return non-zero error to abort walk.
 */
static int
db_show_rtentry(struct rtentry *rt, void *w)
{
        db_printf("rtentry=%p", rt);

        db_printf(" flags=0x%x refcnt=%d use=%ld expire=%lld\n",
                          rt->rt_flags, rt->rt_refcnt,
                          rt->rt_use, (long long)rt->rt_expire);

        db_printf(" key="); db_print_sa(rt_getkey(rt));
        db_printf(" mask="); db_print_sa(rt_mask(rt));
        db_printf(" gw="); db_print_sa(rt->rt_gateway);

        db_printf(" ifp=%p ", rt->rt_ifp);
        if (rt->rt_ifp)
                db_printf("(%s)", rt->rt_ifp->if_xname);
        else
                db_printf("(NULL)");

        db_printf(" ifa=%p\n", rt->rt_ifa);
        db_print_ifa(rt->rt_ifa);

        db_printf(" gwroute=%p llinfo=%p\n",
                          rt->rt_gwroute, rt->rt_llinfo);
        db_print_llinfo(rt->rt_llinfo);

        return 0;
}

/*
 * Function to print all the route trees.
 * Use this from ddb:  "show arptab"
 */
void
db_show_arptab(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
        rt_walktree(AF_INET, db_show_rtentry, NULL);
}
#endif

static int
sysctl_net_inet_arp_stats(SYSCTLFN_ARGS)
{

        return NETSTAT_SYSCTL(arpstat_percpu, ARP_NSTATS);
}

static void
sysctl_net_inet_arp_setup(struct sysctllog **clog)
{
        const struct sysctlnode *node;

        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_NODE, "net", NULL,
                        NULL, 0, NULL, 0,
                        CTL_NET, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_NODE, "inet", NULL,
                        NULL, 0, NULL, 0,
                        CTL_NET, PF_INET, CTL_EOL);
        sysctl_createv(clog, 0, NULL, &node,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_NODE, "arp",
                        SYSCTL_DESCR("Address Resolution Protocol"),
                        NULL, 0, NULL, 0,
                        CTL_NET, PF_INET, CTL_CREATE, CTL_EOL);

        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                        CTLTYPE_INT, "prune",
                        SYSCTL_DESCR("ARP cache pruning interval"),
                        NULL, 0, &arpt_prune, 0,
                        CTL_NET,PF_INET, node->sysctl_num, CTL_CREATE, CTL_EOL);

        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                        CTLTYPE_INT, "keep",
                        SYSCTL_DESCR("Valid ARP entry lifetime"),
                        NULL, 0, &arpt_keep, 0,
                        CTL_NET,PF_INET, node->sysctl_num, CTL_CREATE, CTL_EOL);

        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                        CTLTYPE_INT, "down",
                        SYSCTL_DESCR("Failed ARP entry lifetime"),
                        NULL, 0, &arpt_down, 0,
                        CTL_NET,PF_INET, node->sysctl_num, CTL_CREATE, CTL_EOL);

        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                        CTLTYPE_INT, "refresh",
                        SYSCTL_DESCR("ARP entry refresh interval"),
                        NULL, 0, &arpt_refresh, 0,
                        CTL_NET,PF_INET, node->sysctl_num, CTL_CREATE, CTL_EOL);
        
        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_STRUCT, "stats",
                        SYSCTL_DESCR("ARP statistics"),
                        sysctl_net_inet_arp_stats, 0, NULL, 0,
                        CTL_NET,PF_INET, node->sysctl_num, CTL_CREATE, CTL_EOL);
}

#endif /* INET */