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[dragonfly/vkernel-mp.git] / sys / netinet / if_ether.c

/*
 * Copyright (c) 2004, 2005 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Jeffrey M. Hsu.
 *
 * 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 DragonFly Project 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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) 2004, 2005 Jeffrey M. Hsu.  All rights reserved.
 *
 * License terms: all terms for the DragonFly license above plus the following:
 *
 * 4. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *
 *      This product includes software developed by Jeffrey M. Hsu
 *      for the DragonFly Project.
 *
 *    This requirement may be waived with permission from Jeffrey Hsu.
 *    Permission will be granted to any DragonFly user for free.
 *    This requirement will sunset and may be removed on Jan 31, 2006,
 *    after which the standard DragonFly license (as shown above) will
 *    apply.
 */

/*
 * 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. 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.
 *
 *      @(#)if_ether.c  8.1 (Berkeley) 6/10/93
 * $FreeBSD: src/sys/netinet/if_ether.c,v 1.64.2.23 2003/04/11 07:23:15 fjoe Exp $
 * $DragonFly: src/sys/netinet/if_ether.c,v 1.35 2006/12/23 00:57:52 swildner Exp $
 */

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

#include "opt_inet.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/syslog.h>

#include <sys/thread2.h>
#include <sys/msgport2.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/if_llc.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>

#include <net/if_arc.h>
#include <net/iso88025.h>

#define SIN(s) ((struct sockaddr_in *)s)
#define SDL(s) ((struct sockaddr_dl *)s)

SYSCTL_DECL(_net_link_ether);
SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");

/* timer values */
static int arpt_prune = (5*60*1); /* walk list every 5 minutes */
static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
static int arpt_down = 20;      /* once declared down, don't send for 20 sec */

SYSCTL_INT(_net_link_ether_inet, OID_AUTO, prune_intvl, CTLFLAG_RW,
           &arpt_prune, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
           &arpt_keep, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, host_down_time, CTLFLAG_RW,
           &arpt_down, 0, "");

#define rt_expire       rt_rmx.rmx_expire

struct llinfo_arp {
        LIST_ENTRY(llinfo_arp) la_le;
        struct  rtentry *la_rt;
        struct  mbuf *la_hold;  /* last packet until resolved/timeout */
        u_short la_preempt;     /* countdown for pre-expiry arps */
        u_short la_asked;       /* #times we QUERIED following expiration */
};

static  LIST_HEAD(, llinfo_arp) llinfo_arp_list[MAXCPU];

static int      arp_maxtries = 5;
static int      useloopback = 1; /* use loopback interface for local traffic */
static int      arp_proxyall = 0;

SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
           &arp_maxtries, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
           &useloopback, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
           &arp_proxyall, 0, "");

static void     arp_rtrequest (int, struct rtentry *, struct rt_addrinfo *);
static void     arprequest (struct ifnet *,
                        struct in_addr *, struct in_addr *, u_char *);
static int      arpintr(struct netmsg *);
static void     arptfree (struct llinfo_arp *);
static void     arptimer (void *);
static struct llinfo_arp
                *arplookup (in_addr_t addr, boolean_t create, boolean_t proxy);
#ifdef INET
static void     in_arpinput (struct mbuf *);
#endif

static struct callout   arptimer_ch[MAXCPU];

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

        crit_enter();
        LIST_FOREACH_MUTABLE(la, &llinfo_arp_list[mycpuid], la_le, nla) {
                if (la->la_rt->rt_expire && la->la_rt->rt_expire <= time_second)
                        arptfree(la);   
        }
        callout_reset(&arptimer_ch[mycpuid], arpt_prune * hz, arptimer, NULL);
        crit_exit();
}

/*
 * Parallel to llc_rtrequest.
 */
static void
arp_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info)
{
        struct sockaddr *gate = rt->rt_gateway;
        struct llinfo_arp *la = rt->rt_llinfo;

        struct sockaddr_dl null_sdl = { sizeof null_sdl, AF_LINK };
        static boolean_t arpinit_done[MAXCPU];

        if (!arpinit_done[mycpuid]) {
                arpinit_done[mycpuid] = TRUE;
                callout_init(&arptimer_ch[mycpuid]);
                callout_reset(&arptimer_ch[mycpuid], hz, arptimer, NULL);
        }
        if (rt->rt_flags & RTF_GATEWAY)
                return;

        switch (req) {
        case RTM_ADD:
                /*
                 * 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) &&
                    SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
                        rt->rt_flags |= RTF_CLONING;
                if (rt->rt_flags & RTF_CLONING) {
                        /*
                         * Case 1: This route should come from a route to iface.
                         */
                        rt_setgate(rt, rt_key(rt),
                                   (struct sockaddr *)&null_sdl);
                        gate = rt->rt_gateway;
                        SDL(gate)->sdl_type = rt->rt_ifp->if_type;
                        SDL(gate)->sdl_index = rt->rt_ifp->if_index;
                        rt->rt_expire = time_second;
                        break;
                }
                /* Announce a new entry if requested. */
                if (rt->rt_flags & RTF_ANNOUNCE)
                        arprequest(rt->rt_ifp,
                            &SIN(rt_key(rt))->sin_addr,
                            &SIN(rt_key(rt))->sin_addr,
                            LLADDR(SDL(gate)));
                /*FALLTHROUGH*/
        case RTM_RESOLVE:
                if (gate->sa_family != AF_LINK ||
                    gate->sa_len < sizeof(struct sockaddr_dl)) {
                        log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
                        break;
                }
                SDL(gate)->sdl_type = rt->rt_ifp->if_type;
                SDL(gate)->sdl_index = rt->rt_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.
                 */
                R_Malloc(la, struct llinfo_arp *, sizeof *la);
                rt->rt_llinfo = la;
                if (la == NULL) {
                        log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
                        break;
                }
                bzero(la, sizeof *la);
                la->la_rt = rt;
                rt->rt_flags |= RTF_LLINFO;
                LIST_INSERT_HEAD(&llinfo_arp_list[mycpuid], la, la_le);

#ifdef INET
                /*
                 * This keeps the multicast addresses from showing up
                 * in `arp -a' listings as unresolved.  It's not actually
                 * functional.  Then the same for broadcast.
                 */
                if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) &&
                    rt->rt_ifp->if_type != IFT_ARCNET) {
                        ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr,
                                               LLADDR(SDL(gate)));
                        SDL(gate)->sdl_alen = 6;
                        rt->rt_expire = 0;
                }
                if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
                        memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr,
                               rt->rt_ifp->if_addrlen);
                        SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen;
                        rt->rt_expire = 0;
                }
#endif

                if (SIN(rt_key(rt))->sin_addr.s_addr ==
                    (IA_SIN(rt->rt_ifa))->sin_addr.s_addr) {
                        /*
                         * This test used to be
                         *      if (loif.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.
                         */
                        rt->rt_expire = 0;
                        bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)),
                              SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen);
                        if (useloopback)
                                rt->rt_ifp = loif;
                }
                break;

        case RTM_DELETE:
                if (la == NULL)
                        break;
                LIST_REMOVE(la, la_le);
                rt->rt_llinfo = NULL;
                rt->rt_flags &= ~RTF_LLINFO;
                if (la->la_hold != NULL)
                        m_freem(la->la_hold);
                Free(la);
        }
}

/*
 * Broadcast an ARP request. Caller specifies:
 *      - arp header source ip address
 *      - arp header target ip address
 *      - arp header source ethernet address
 */
static void
arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
           u_char *enaddr)
{
        struct mbuf *m;
        struct ether_header *eh;
        struct arc_header *arh;
        struct arphdr *ah;
        struct sockaddr sa;
        static u_char llcx[] = { 0x82, 0x40, LLC_SNAP_LSAP, LLC_SNAP_LSAP,
                                 LLC_UI, 0x00, 0x00, 0x00, 0x08, 0x06 };
        u_short ar_hrd;

        if ((m = m_gethdr(MB_DONTWAIT, MT_DATA)) == NULL)
                return;
        m->m_pkthdr.rcvif = (struct ifnet *)NULL;

        switch (ifp->if_type) {
        case IFT_ARCNET:
                ar_hrd = htons(ARPHRD_ARCNET);

                m->m_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
                m->m_pkthdr.len = m->m_len;
                MH_ALIGN(m, m->m_len);

                arh = (struct arc_header *)sa.sa_data;
                arh->arc_dhost = ifp->if_broadcastaddr[0];
                arh->arc_type = ARCTYPE_ARP;

                ah = mtod(m, struct arphdr *);
                break;

        case IFT_ISO88025:
                ar_hrd = htons(ARPHRD_IEEE802);

                m->m_len = (sizeof llcx) +
                    arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
                m->m_pkthdr.len = m->m_len;
                MH_ALIGN(m, m->m_len);

                memcpy(mtod(m, caddr_t), llcx, sizeof llcx);
                memcpy(sa.sa_data, ifp->if_broadcastaddr, ifp->if_addrlen);
                memcpy(sa.sa_data + 6, enaddr, 6);
                sa.sa_data[6] |= TR_RII;
                sa.sa_data[12] = TR_AC;
                sa.sa_data[13] = TR_LLC_FRAME;

                ah = (struct arphdr *)(mtod(m, char *) + sizeof llcx);
                break;
        case IFT_FDDI:
        case IFT_ETHER:
                /*
                 * This may not be correct for types not explicitly
                 * listed, but this is our best guess
                 */
        default:
                ar_hrd = htons(ARPHRD_ETHER);

                m->m_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
                m->m_pkthdr.len = m->m_len;
                MH_ALIGN(m, m->m_len);

                eh = (struct ether_header *)sa.sa_data;
                /* if_output() will not swap */
                eh->ether_type = htons(ETHERTYPE_ARP);
                memcpy(eh->ether_dhost, ifp->if_broadcastaddr, ifp->if_addrlen);

                ah = mtod(m, struct arphdr *);
                break;
        }

        ah->ar_hrd = ar_hrd;
        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);
        memset(ar_tha(ah), 0, ah->ar_hln);
        memcpy(ar_spa(ah), sip, ah->ar_pln);
        memcpy(ar_tpa(ah), tip, ah->ar_pln);

        sa.sa_family = AF_UNSPEC;
        sa.sa_len = sizeof sa;
        (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)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 *rt0,
        struct mbuf *m,
        struct sockaddr *dst,
        u_char *desten)
{
        struct rtentry *rt;
        struct llinfo_arp *la = NULL;
        struct sockaddr_dl *sdl;

        if (m->m_flags & M_BCAST) {     /* broadcast */
                memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen);
                return (1);
        }
        if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */
                ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
                return (1);
        }
        if (rt0 != NULL) {
                if (rt_llroute(dst, rt0, &rt) != 0) {
                        m_freem(m);
                        return 0;
                }
                la = rt->rt_llinfo;
        }
        if (la == NULL) {
                la = arplookup(SIN(dst)->sin_addr.s_addr, TRUE, FALSE);
                if (la != NULL)
                        rt = la->la_rt;
        }
        if (la == NULL || rt == NULL) {
                log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s%s%s\n",
                    inet_ntoa(SIN(dst)->sin_addr), la ? "la" : " ",
                    rt ? "rt" : "");
                m_freem(m);
                return (0);
        }
        sdl = SDL(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) {
                /*
                 * If entry has an expiry time and it is approaching,
                 * see if we need to send an ARP request within this
                 * arpt_down interval.
                 */
                if ((rt->rt_expire != 0) &&
                    (time_second + la->la_preempt > rt->rt_expire)) {
                        arprequest(ifp,
                                   &SIN(rt->rt_ifa->ifa_addr)->sin_addr,
                                   &SIN(dst)->sin_addr,
                                   IF_LLADDR(ifp));
                        la->la_preempt--;
                }

                bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
                return 1;
        }
        /*
         * If ARP is disabled on this interface, stop.
         * XXX
         * Probably should not allocate empty llinfo struct if we are
         * not going to be sending out an arp request.
         */
        if (ifp->if_flags & IFF_NOARP) {
                m_freem(m);
                return (0);
        }
        /*
         * There is an arptab entry, but no ethernet address
         * response yet.  Replace the held mbuf with this
         * latest one.
         */
        if (la->la_hold != NULL)
                m_freem(la->la_hold);
        la->la_hold = m;
        if (rt->rt_expire || ((rt->rt_flags & RTF_STATIC) && !sdl->sdl_alen)) {
                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,
                                           &SIN(rt->rt_ifa->ifa_addr)->sin_addr,
                                           &SIN(dst)->sin_addr,
                                           IF_LLADDR(ifp));
                        } else {
                                rt->rt_flags |= RTF_REJECT;
                                rt->rt_expire += arpt_down;
                                la->la_asked = 0;
                                la->la_preempt = arp_maxtries;
                        }

                }
        }
        return (0);
}

/*
 * Common length and type checks are done here,
 * then the protocol-specific routine is called.
 */
static int
arpintr(struct netmsg *msg)
{
        struct mbuf *m = ((struct netmsg_packet *)msg)->nm_packet;
        struct arphdr *ar;
        u_short ar_hrd;

        if (m->m_len < sizeof(struct arphdr) &&
            ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
                log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
                goto out2;
        }
        ar = mtod(m, struct arphdr *);

        ar_hrd = ntohs(ar->ar_hrd);
        if (ar_hrd != ARPHRD_ETHER &&
            ar_hrd != ARPHRD_IEEE802 &&
            ar_hrd != ARPHRD_ARCNET) {
                log(LOG_ERR,
                    "arp: unknown hardware address format (0x%2D)\n",
                    (unsigned char *)&ar->ar_hrd, "");
                goto out1;
        }

        if (m->m_pkthdr.len < arphdr_len(ar) &&
            (m = m_pullup(m, arphdr_len(ar))) == NULL) {
                log(LOG_ERR, "arp: runt packet\n");
                goto out1;
        }

        switch (ntohs(ar->ar_pro)) {
#ifdef INET
                case ETHERTYPE_IP:
                        in_arpinput(m);
                        goto out2;
#endif
        }
out1:
        m_freem(m);
out2:
        /* msg was embedded in the mbuf, do not reply! */
        return(EASYNC);
}

#ifdef INET
/*
 * 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 int log_arp_wrong_iface = 1;
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
        &log_arp_wrong_iface, 0,
        "log arp packets arriving on the wrong interface");

static void
arp_update_oncpu(struct mbuf *m, in_addr_t saddr, boolean_t create,
                 boolean_t dologging)
{
        struct arphdr *ah = mtod(m, struct arphdr *);
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        struct llinfo_arp *la;
        struct sockaddr_dl *sdl;
        struct rtentry *rt;
        int cpu = mycpuid;

        la = arplookup(saddr, create, FALSE);
        if (la && (rt = la->la_rt) && (sdl = SDL(rt->rt_gateway))) {
                struct in_addr isaddr = { saddr };

                /* the following is not an error when doing bridging */
                if (rt->rt_ifp != ifp) {
                        if (dologging && log_arp_wrong_iface && cpu == 0) {
                                log(LOG_ERR,
                                    "arp: %s is on %s "
                                    "but got reply from %*D on %s\n",
                                    inet_ntoa(isaddr),
                                    rt->rt_ifp->if_xname,
                                    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
                                    ifp->if_xname);
                        }
                        return;
                }
                if (sdl->sdl_alen &&
                    bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) {
                        if (rt->rt_expire != 0) {
                                if (dologging && cpu == 0) {
                                        log(LOG_INFO,
                                        "arp: %s moved from %*D to %*D on %s\n",
                                        inet_ntoa(isaddr),
                                        ifp->if_addrlen, (u_char *)LLADDR(sdl),
                                        ":", ifp->if_addrlen,
                                        (u_char *)ar_sha(ah), ":",
                                        ifp->if_xname);
                                }
                        } else {
                                if (dologging && cpu == 0) {
                                        log(LOG_ERR,
                                        "arp: %*D attempts to modify permanent entry for %s on %s\n",
                                        ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
                                        inet_ntoa(isaddr), ifp->if_xname);
                                }
                                return;
                        }
                }
                /*
                 * sanity check for the address length.
                 * XXX this does not work for protocols with variable address
                 * length. -is
                 */
                if (dologging && sdl->sdl_alen && sdl->sdl_alen != ah->ar_hln &&
                    cpu == 0)
                {
                        log(LOG_WARNING,
                            "arp from %*D: new addr len %d, was %d",
                            ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
                            ah->ar_hln, sdl->sdl_alen);
                }
                if (ifp->if_addrlen != ah->ar_hln) {
                        if (dologging && cpu == 0) {
                                log(LOG_WARNING,
                                "arp from %*D: addr len: new %d, i/f %d (ignored)",
                                ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
                                ah->ar_hln, ifp->if_addrlen);
                        }
                        return;
                }
                memcpy(LLADDR(sdl), ar_sha(ah), sdl->sdl_alen = ah->ar_hln);
                /*
                 * If we receive an arp from a token-ring station over
                 * a token-ring nic then try to save the source
                 * routing info.
                 */
                if (ifp->if_type == IFT_ISO88025) {
                        struct iso88025_header *th =
                            (struct iso88025_header *)m->m_pkthdr.header;
                        struct iso88025_sockaddr_dl_data *trld =
                            SDL_ISO88025(sdl);
                        int rif_len;

                        rif_len = TR_RCF_RIFLEN(th->rcf);
                        if ((th->iso88025_shost[0] & TR_RII) &&
                            (rif_len > 2)) {
                                trld->trld_rcf = th->rcf;
                                trld->trld_rcf ^= htons(TR_RCF_DIR);
                                memcpy(trld->trld_route, th->rd, rif_len - 2);
                                trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK);
                                /*
                                 * Set up source routing information for
                                 * reply packet (XXX)
                                 */
                                m->m_data -= rif_len;
                                m->m_len  += rif_len;
                                m->m_pkthdr.len += rif_len;
                        } else {
                                th->iso88025_shost[0] &= ~TR_RII;
                                trld->trld_rcf = 0;
                        }
                        m->m_data -= 8;
                        m->m_len  += 8;
                        m->m_pkthdr.len += 8;
                        th->rcf = trld->trld_rcf;
                }
                if (rt->rt_expire != 0)
                        rt->rt_expire = time_second + arpt_keep;
                rt->rt_flags &= ~RTF_REJECT;
                la->la_asked = 0;
                la->la_preempt = arp_maxtries;

                /*
                 * This particular cpu might have been holding an mbuf
                 * pending ARP resolution.  If so, transmit the mbuf now.
                 */
                if (la->la_hold != NULL) {
                        m_adj(la->la_hold, sizeof(struct ether_header));
                        lwkt_serialize_enter(ifp->if_serializer);
                        (*ifp->if_output)(ifp, la->la_hold, rt_key(rt), rt);
                        lwkt_serialize_exit(ifp->if_serializer);
                        la->la_hold = NULL;
                }
        }
}

#ifdef SMP

struct netmsg_arp_update {
        struct lwkt_msg lmsg;
        struct mbuf     *m;
        in_addr_t       saddr;
        boolean_t       create;
};

static int arp_update_msghandler(struct lwkt_msg *lmsg);

#endif

/*
 * Called from arpintr() - this routine is run from a single cpu.
 */
static void
in_arpinput(struct mbuf *m)
{
        struct arphdr *ah;
        struct ifnet *ifp = m->m_pkthdr.rcvif;
        struct ether_header *eh;
        struct arc_header *arh;
        struct iso88025_header *th = (struct iso88025_header *)NULL;
        struct rtentry *rt;
        struct ifaddr *ifa;
        struct in_ifaddr *ia;
        struct sockaddr sa;
        struct in_addr isaddr, itaddr, myaddr;
#ifdef SMP
        struct netmsg_arp_update msg;
#endif
        int op;
        int req_len;

        req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
        if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
                log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
                return;
        }

        ah = mtod(m, struct arphdr *);
        op = ntohs(ah->ar_op);
        memcpy(&isaddr, ar_spa(ah), sizeof isaddr);
        memcpy(&itaddr, ar_tpa(ah), sizeof itaddr);
        /*
         * Check both target and sender IP addresses:
         *
         * If we receive the packet on the interface owning the address,
         * then accept the address.
         *
         * For a bridge, we accept the address if the receive interface and
         * the interface owning the address are on the same bridge.
         * (This will change slightly when we have clusters of interfaces).
         */
        LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
                /* Skip all ia's which don't match */
                if (itaddr.s_addr != ia->ia_addr.sin_addr.s_addr)
                        continue;

                if (ia->ia_ifp == ifp)
                        goto match;

                if (ifp->if_bridge && ia->ia_ifp && 
                    ifp->if_bridge == ia->ia_ifp->if_bridge)
                        goto match;
        }
        LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) {
                /* Skip all ia's which don't match */
                if (isaddr.s_addr != ia->ia_addr.sin_addr.s_addr)
                        continue;

                if (ia->ia_ifp == ifp)
                        goto match;

                if (ifp->if_bridge && ia->ia_ifp &&
                    ifp->if_bridge == ia->ia_ifp->if_bridge)
                        goto match;
        }
        /*
         * No match, use the first inet address on the receive interface
         * as a dummy address for the rest of the function.
         */
        TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                if (ifa->ifa_addr && ifa->ifa_addr->sa_family == AF_INET) {
                        ia = ifatoia(ifa);
                        goto match;
                }
        }
        /*
         * If we got here, we didn't find any suitable interface,
         * so drop the packet.
         */
        m_freem(m);
        return;

match:
        myaddr = ia->ia_addr.sin_addr;
        if (!bcmp(ar_sha(ah), IF_LLADDR(ifp), ifp->if_addrlen)) {
                m_freem(m);     /* it's from me, ignore it. */
                return;
        }
        if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
                log(LOG_ERR,
                    "arp: link address is broadcast for IP address %s!\n",
                    inet_ntoa(isaddr));
                m_freem(m);
                return;
        }
        if (isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
                log(LOG_ERR,
                   "arp: %*D is using my IP address %s!\n",
                   ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
                   inet_ntoa(isaddr));
                itaddr = myaddr;
                goto reply;
        }
#ifdef SMP
        lwkt_initmsg(&msg.lmsg, &curthread->td_msgport, 0, 
                     lwkt_cmd_func(arp_update_msghandler), lwkt_cmd_op_none);
        msg.m = m;
        msg.saddr = isaddr.s_addr;
        msg.create = (itaddr.s_addr == myaddr.s_addr);
        lwkt_domsg(rtable_portfn(0), &msg.lmsg);
#endif
        arp_update_oncpu(m, isaddr.s_addr, (itaddr.s_addr == myaddr.s_addr),
                         TRUE);
reply:
        if (op != ARPOP_REQUEST) {
                m_freem(m);
                return;
        }
        if (itaddr.s_addr == myaddr.s_addr) {
                /* I am the target */
                memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
                memcpy(ar_sha(ah), IF_LLADDR(ifp), ah->ar_hln);
        } else {
                struct llinfo_arp *la;

                la = arplookup(itaddr.s_addr, FALSE, SIN_PROXY);
                if (la == NULL) {
                        struct sockaddr_in sin;

                        if (!arp_proxyall) {
                                m_freem(m);
                                return;
                        }

                        bzero(&sin, sizeof sin);
                        sin.sin_family = AF_INET;
                        sin.sin_len = sizeof sin;
                        sin.sin_addr = itaddr;

                        rt = rtpurelookup((struct sockaddr *)&sin);
                        if (rt == NULL) {
                                m_freem(m);
                                return;
                        }
                        --rt->rt_refcnt;
                        /*
                         * Don't send proxies for nodes on the same interface
                         * as this one came out of, or we'll get into a fight
                         * over who claims what Ether address.
                         */
                        if (rt->rt_ifp == ifp) {
                                m_freem(m);
                                return;
                        }
                        memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
                        memcpy(ar_sha(ah), IF_LLADDR(ifp), ah->ar_hln);
#ifdef DEBUG_PROXY
                        kprintf("arp: proxying for %s\n", inet_ntoa(itaddr));
#endif
                } else {
                        struct sockaddr_dl *sdl;

                        rt = la->la_rt;
                        memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
                        sdl = SDL(rt->rt_gateway);
                        memcpy(ar_sha(ah), LLADDR(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_ARCNET:
                arh = (struct arc_header *)sa.sa_data;
                arh->arc_dhost = *ar_tha(ah);
                arh->arc_type = ARCTYPE_ARP;
                break;
        case IFT_ISO88025:
                /* Re-arrange the source/dest address */
                memcpy(th->iso88025_dhost, th->iso88025_shost,
                    sizeof th->iso88025_dhost);
                memcpy(th->iso88025_shost, IF_LLADDR(ifp),
                    sizeof th->iso88025_shost);
                /* Set the source routing bit if neccesary */
                if (th->iso88025_dhost[0] & TR_RII) {
                        th->iso88025_dhost[0] &= ~TR_RII;
                        if (TR_RCF_RIFLEN(th->rcf) > 2)
                                th->iso88025_shost[0] |= TR_RII;
                }
                /* Copy the addresses, ac and fc into sa_data */
                memcpy(sa.sa_data, th->iso88025_dhost,
                    (sizeof th->iso88025_dhost) * 2);
                sa.sa_data[(sizeof th->iso88025_dhost) * 2] = TR_AC;
                sa.sa_data[(sizeof th->iso88025_dhost) * 2 + 1] = TR_LLC_FRAME;
                break;
        case IFT_ETHER:
        case IFT_FDDI:
        /*
         * May not be correct for types not explictly
         * listed, but it is our best guess.
         */
        default:
                eh = (struct ether_header *)sa.sa_data;
                memcpy(eh->ether_dhost, ar_tha(ah), sizeof eh->ether_dhost);
                eh->ether_type = htons(ETHERTYPE_ARP);
                break;
        }
        sa.sa_family = AF_UNSPEC;
        sa.sa_len = sizeof sa;
        lwkt_serialize_enter(ifp->if_serializer);
        (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
        lwkt_serialize_exit(ifp->if_serializer);
        return;
}

#ifdef SMP

static
int
arp_update_msghandler(struct lwkt_msg *lmsg)
{
        struct netmsg_arp_update *msg = (struct netmsg_arp_update *)lmsg;
        int nextcpu;

        arp_update_oncpu(msg->m, msg->saddr, msg->create, FALSE);

        nextcpu = mycpuid + 1;
        if (nextcpu < ncpus) {
                lwkt_forwardmsg(rtable_portfn(nextcpu), &msg->lmsg);
        } else {
                lwkt_replymsg(&msg->lmsg, 0);
        }
        return (0);
}

#endif

#endif

/*
 * Free an arp entry.  If the arp entry is actively referenced or represents
 * a static entry we only clear it back to an unresolved state, otherwise
 * we destroy the entry entirely.
 *
 * Note that static entries are created when route add ... -interface is used
 * to create an interface route to a (direct) destination.
 */
static void
arptfree(struct llinfo_arp *la)
{
        struct rtentry *rt = la->la_rt;
        struct sockaddr_dl *sdl;

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

/*
 * Lookup or enter a new address in arptab.
 */
static struct llinfo_arp *
arplookup(in_addr_t addr, boolean_t create, boolean_t proxy)
{
        struct rtentry *rt;
        struct sockaddr_inarp sin = { sizeof sin, AF_INET };
        const char *why = NULL;

        sin.sin_addr.s_addr = addr;
        sin.sin_other = proxy ? SIN_PROXY : 0;
        if (create)
                rt = rtlookup((struct sockaddr *)&sin);
        else
                rt = rtpurelookup((struct sockaddr *)&sin);
        if (rt == NULL)
                return (NULL);
        rt->rt_refcnt--;

        if (rt->rt_flags & RTF_GATEWAY)
                why = "host is not on local network";
        else if (!(rt->rt_flags & RTF_LLINFO))
                why = "could not allocate llinfo";
        else if (rt->rt_gateway->sa_family != AF_LINK)
                why = "gateway route is not ours";

        if (why) {
                if (create) {
                        log(LOG_DEBUG, "arplookup %s failed: %s\n",
                            inet_ntoa(sin.sin_addr), why);
                }
                if (rt->rt_refcnt <= 0 && (rt->rt_flags & RTF_WASCLONED)) {
                        /* No references to this route.  Purge it. */
                        rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
                                  rt_mask(rt), rt->rt_flags, NULL);
                }
                return (NULL);
        }
        return (rt->rt_llinfo);
}

void
arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
{
        if (IA_SIN(ifa)->sin_addr.s_addr != INADDR_ANY)
                arprequest(ifp, &IA_SIN(ifa)->sin_addr, &IA_SIN(ifa)->sin_addr,
                           IF_LLADDR(ifp));
        ifa->ifa_rtrequest = arp_rtrequest;
        ifa->ifa_flags |= RTF_CLONING;
}

static void
arp_init(void)
{
        int cpu;

        for (cpu = 0; cpu < ncpus2; cpu++)
                LIST_INIT(&llinfo_arp_list[cpu]);
        netisr_register(NETISR_ARP, cpu0_portfn, arpintr);
}

SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);