The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/if_ether.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)if_ether.c  8.1 (Berkeley) 6/10/93
   30  */
   31 
   32 /*
   33  * Ethernet address resolution protocol.
   34  * TODO:
   35  *      add "inuse/lock" bit (or ref. count) along with valid bit
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/10.4/sys/netinet/if_ether.c 309340 2016-11-30 22:20:23Z vangyzen $");
   40 
   41 #include "opt_inet.h"
   42 
   43 #include <sys/param.h>
   44 #include <sys/kernel.h>
   45 #include <sys/queue.h>
   46 #include <sys/sysctl.h>
   47 #include <sys/systm.h>
   48 #include <sys/mbuf.h>
   49 #include <sys/malloc.h>
   50 #include <sys/proc.h>
   51 #include <sys/socket.h>
   52 #include <sys/syslog.h>
   53 
   54 #include <net/if.h>
   55 #include <net/if_dl.h>
   56 #include <net/if_types.h>
   57 #include <net/netisr.h>
   58 #include <net/if_llc.h>
   59 #include <net/ethernet.h>
   60 #include <net/route.h>
   61 #include <net/vnet.h>
   62 
   63 #include <netinet/in.h>
   64 #include <netinet/in_var.h>
   65 #include <net/if_llatbl.h>
   66 #include <netinet/if_ether.h>
   67 #ifdef INET
   68 #include <netinet/ip_carp.h>
   69 #endif
   70 
   71 #include <net/if_arc.h>
   72 #include <net/iso88025.h>
   73 
   74 #include <security/mac/mac_framework.h>
   75 
   76 #define SIN(s) ((const struct sockaddr_in *)(s))
   77 #define SDL(s) ((struct sockaddr_dl *)s)
   78 
   79 SYSCTL_DECL(_net_link_ether);
   80 static SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
   81 static SYSCTL_NODE(_net_link_ether, PF_ARP, arp, CTLFLAG_RW, 0, "");
   82 
   83 /* timer values */
   84 static VNET_DEFINE(int, arpt_keep) = (20*60);   /* once resolved, good for 20
   85                                                  * minutes */
   86 static VNET_DEFINE(int, arp_maxtries) = 5;
   87 VNET_DEFINE(int, useloopback) = 1;      /* use loopback interface for
   88                                          * local traffic */
   89 static VNET_DEFINE(int, arp_proxyall) = 0;
   90 static VNET_DEFINE(int, arpt_down) = 20;        /* keep incomplete entries for
   91                                                  * 20 seconds */
   92 VNET_PCPUSTAT_DEFINE(struct arpstat, arpstat);  /* ARP statistics, see if_arp.h */
   93 VNET_PCPUSTAT_SYSINIT(arpstat);
   94 
   95 #ifdef VIMAGE
   96 VNET_PCPUSTAT_SYSUNINIT(arpstat);
   97 #endif /* VIMAGE */
   98 
   99 static VNET_DEFINE(int, arp_maxhold) = 1;
  100 
  101 #define V_arpt_keep             VNET(arpt_keep)
  102 #define V_arpt_down             VNET(arpt_down)
  103 #define V_arp_maxtries          VNET(arp_maxtries)
  104 #define V_arp_proxyall          VNET(arp_proxyall)
  105 #define V_arp_maxhold           VNET(arp_maxhold)
  106 
  107 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
  108         &VNET_NAME(arpt_keep), 0,
  109         "ARP entry lifetime in seconds");
  110 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
  111         &VNET_NAME(arp_maxtries), 0,
  112         "ARP resolution attempts before returning error");
  113 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
  114         &VNET_NAME(useloopback), 0,
  115         "Use the loopback interface for local traffic");
  116 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
  117         &VNET_NAME(arp_proxyall), 0,
  118         "Enable proxy ARP for all suitable requests");
  119 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW,
  120         &VNET_NAME(arpt_down), 0,
  121         "Incomplete ARP entry lifetime in seconds");
  122 SYSCTL_VNET_PCPUSTAT(_net_link_ether_arp, OID_AUTO, stats, struct arpstat,
  123     arpstat, "ARP statistics (struct arpstat, net/if_arp.h)");
  124 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW,
  125         &VNET_NAME(arp_maxhold), 0,
  126         "Number of packets to hold per ARP entry");
  127 
  128 /*
  129  * Due to the exponential backoff algorithm used for the interval between GARP
  130  * retransmissions, the maximum number of retransmissions is limited for
  131  * sanity. This limit corresponds to a maximum interval between retransmissions
  132  * of 2^16 seconds ~= 18 hours.
  133  *
  134  * Making this limit more dynamic is more complicated than worthwhile,
  135  * especially since sending out GARPs spaced days apart would be of little
  136  * use. A maximum dynamic limit would look something like:
  137  *
  138  * const int max = fls(INT_MAX / hz) - 1;
  139  */
  140 #define MAX_GARP_RETRANSMITS 16
  141 static int sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS);
  142 static int garp_rexmit_count = 0; /* GARP retransmission setting. */
  143 
  144 SYSCTL_PROC(_net_link_ether_inet, OID_AUTO, garp_rexmit_count,
  145     CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
  146     &garp_rexmit_count, 0, sysctl_garp_rexmit, "I",
  147     "Number of times to retransmit GARP packets;"
  148     " 0 to disable, maximum of 16");
  149 
  150 static void     arp_init(void);
  151 static void     arpintr(struct mbuf *);
  152 static void     arptimer(void *);
  153 #ifdef INET
  154 static void     in_arpinput(struct mbuf *);
  155 #endif
  156 
  157 static const struct netisr_handler arp_nh = {
  158         .nh_name = "arp",
  159         .nh_handler = arpintr,
  160         .nh_proto = NETISR_ARP,
  161         .nh_policy = NETISR_POLICY_SOURCE,
  162 };
  163 
  164 #ifdef AF_INET
  165 /*
  166  * called by in_ifscrub to remove entry from the table when
  167  * the interface goes away
  168  */
  169 void
  170 arp_ifscrub(struct ifnet *ifp, uint32_t addr)
  171 {
  172         struct sockaddr_in addr4;
  173 
  174         bzero((void *)&addr4, sizeof(addr4));
  175         addr4.sin_len    = sizeof(addr4);
  176         addr4.sin_family = AF_INET;
  177         addr4.sin_addr.s_addr = addr;
  178         IF_AFDATA_WLOCK(ifp);
  179         lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
  180             (struct sockaddr *)&addr4);
  181         IF_AFDATA_WUNLOCK(ifp);
  182 }
  183 #endif
  184 
  185 /*
  186  * Timeout routine.  Age arp_tab entries periodically.
  187  */
  188 static void
  189 arptimer(void *arg)
  190 {
  191         struct llentry *lle = (struct llentry *)arg;
  192         struct ifnet *ifp;
  193 
  194         if (lle->la_flags & LLE_STATIC) {
  195                 return;
  196         }
  197         LLE_WLOCK(lle);
  198         if (callout_pending(&lle->la_timer)) {
  199                 /*
  200                  * Here we are a bit odd here in the treatment of 
  201                  * active/pending. If the pending bit is set, it got
  202                  * rescheduled before I ran. The active
  203                  * bit we ignore, since if it was stopped
  204                  * in ll_tablefree() and was currently running
  205                  * it would have return 0 so the code would
  206                  * not have deleted it since the callout could
  207                  * not be stopped so we want to go through
  208                  * with the delete here now. If the callout
  209                  * was restarted, the pending bit will be back on and
  210                  * we just want to bail since the callout_reset would
  211                  * return 1 and our reference would have been removed
  212                  * by arpresolve() below.
  213                  */
  214                 LLE_WUNLOCK(lle);
  215                 return;
  216         }
  217         ifp = lle->lle_tbl->llt_ifp;
  218         CURVNET_SET(ifp->if_vnet);
  219 
  220         if ((lle->la_flags & LLE_DELETED) == 0) {
  221                 int evt;
  222 
  223                 if (lle->la_flags & LLE_VALID)
  224                         evt = LLENTRY_EXPIRED;
  225                 else
  226                         evt = LLENTRY_TIMEDOUT;
  227                 EVENTHANDLER_INVOKE(lle_event, lle, evt);
  228         }
  229 
  230         callout_stop(&lle->la_timer);
  231 
  232         /* XXX: LOR avoidance. We still have ref on lle. */
  233         LLE_WUNLOCK(lle);
  234         IF_AFDATA_LOCK(ifp);
  235         LLE_WLOCK(lle);
  236 
  237         /* Guard against race with other llentry_free(). */
  238         if (lle->la_flags & LLE_LINKED) {
  239                 size_t pkts_dropped;
  240 
  241                 LLE_REMREF(lle);
  242                 pkts_dropped = llentry_free(lle);
  243                 ARPSTAT_ADD(dropped, pkts_dropped);
  244         } else
  245                 LLE_FREE_LOCKED(lle);
  246 
  247         IF_AFDATA_UNLOCK(ifp);
  248 
  249         ARPSTAT_INC(timeouts);
  250 
  251         CURVNET_RESTORE();
  252 }
  253 
  254 /*
  255  * Broadcast an ARP request. Caller specifies:
  256  *      - arp header source ip address
  257  *      - arp header target ip address
  258  *      - arp header source ethernet address
  259  */
  260 void
  261 arprequest(struct ifnet *ifp, const struct in_addr *sip,
  262     const struct in_addr *tip, u_char *enaddr)
  263 {
  264         struct mbuf *m;
  265         struct arphdr *ah;
  266         struct sockaddr sa;
  267         u_char *carpaddr = NULL;
  268 
  269         if (sip == NULL) {
  270                 /*
  271                  * The caller did not supply a source address, try to find
  272                  * a compatible one among those assigned to this interface.
  273                  */
  274                 struct ifaddr *ifa;
  275 
  276                 IF_ADDR_RLOCK(ifp);
  277                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  278                         if (ifa->ifa_addr->sa_family != AF_INET)
  279                                 continue;
  280 
  281                         if (ifa->ifa_carp) {
  282                                 if ((*carp_iamatch_p)(ifa, &carpaddr) == 0)
  283                                         continue;
  284                                 sip = &IA_SIN(ifa)->sin_addr;
  285                         } else {
  286                                 carpaddr = NULL;
  287                                 sip = &IA_SIN(ifa)->sin_addr;
  288                         }
  289 
  290                         if (0 == ((sip->s_addr ^ tip->s_addr) &
  291                             IA_MASKSIN(ifa)->sin_addr.s_addr))
  292                                 break;  /* found it. */
  293                 }
  294                 IF_ADDR_RUNLOCK(ifp);
  295                 if (sip == NULL) {
  296                         printf("%s: cannot find matching address\n", __func__);
  297                         return;
  298                 }
  299         }
  300         if (enaddr == NULL)
  301                 enaddr = carpaddr ? carpaddr : (u_char *)IF_LLADDR(ifp);
  302 
  303         if ((m = m_gethdr(M_NOWAIT, MT_DATA)) == NULL)
  304                 return;
  305         m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
  306                 2*ifp->if_data.ifi_addrlen;
  307         m->m_pkthdr.len = m->m_len;
  308         MH_ALIGN(m, m->m_len);
  309         ah = mtod(m, struct arphdr *);
  310         bzero((caddr_t)ah, m->m_len);
  311 #ifdef MAC
  312         mac_netinet_arp_send(ifp, m);
  313 #endif
  314         ah->ar_pro = htons(ETHERTYPE_IP);
  315         ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
  316         ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
  317         ah->ar_op = htons(ARPOP_REQUEST);
  318         bcopy(enaddr, ar_sha(ah), ah->ar_hln);
  319         bcopy(sip, ar_spa(ah), ah->ar_pln);
  320         bcopy(tip, ar_tpa(ah), ah->ar_pln);
  321         sa.sa_family = AF_ARP;
  322         sa.sa_len = 2;
  323         m->m_flags |= M_BCAST;
  324         m_clrprotoflags(m);     /* Avoid confusing lower layers. */
  325         (*ifp->if_output)(ifp, m, &sa, NULL);
  326         ARPSTAT_INC(txrequests);
  327 }
  328 
  329 /*
  330  * Resolve an IP address into an ethernet address.
  331  * On input:
  332  *    ifp is the interface we use
  333  *    rt0 is the route to the final destination (possibly useless)
  334  *    m is the mbuf. May be NULL if we don't have a packet.
  335  *    dst is the next hop,
  336  *    desten is where we want the address.
  337  *
  338  * On success, desten is filled in and the function returns 0;
  339  * If the packet must be held pending resolution, we return EWOULDBLOCK
  340  * On other errors, we return the corresponding error code.
  341  * Note that m_freem() handles NULL.
  342  */
  343 int
  344 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
  345         const struct sockaddr *dst, u_char *desten, struct llentry **lle)
  346 {
  347         struct llentry *la = 0;
  348         u_int flags = 0;
  349         struct mbuf *curr = NULL;
  350         struct mbuf *next = NULL;
  351         int error, renew;
  352 
  353         *lle = NULL;
  354         if (m != NULL) {
  355                 if (m->m_flags & M_BCAST) {
  356                         /* broadcast */
  357                         (void)memcpy(desten,
  358                             ifp->if_broadcastaddr, ifp->if_addrlen);
  359                         return (0);
  360                 }
  361                 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
  362                         /* multicast */
  363                         ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
  364                         return (0);
  365                 }
  366         }
  367 retry:
  368         IF_AFDATA_RLOCK(ifp);
  369         la = lla_lookup(LLTABLE(ifp), flags, dst);
  370         IF_AFDATA_RUNLOCK(ifp);
  371         if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
  372             && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
  373                 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
  374                 IF_AFDATA_WLOCK(ifp);
  375                 la = lla_lookup(LLTABLE(ifp), flags, dst);
  376                 IF_AFDATA_WUNLOCK(ifp);
  377         }
  378         if (la == NULL) {
  379                 if (flags & LLE_CREATE)
  380                         log(LOG_DEBUG,
  381                             "arpresolve: can't allocate llinfo for %s on %s\n",
  382                             inet_ntoa(SIN(dst)->sin_addr), ifp->if_xname);
  383                 m_freem(m);
  384                 return (EINVAL);
  385         }
  386 
  387         if ((la->la_flags & LLE_VALID) &&
  388             ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
  389                 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
  390                 renew = 0;
  391                 /*
  392                  * If entry has an expiry time and it is approaching,
  393                  * see if we need to send an ARP request within this
  394                  * arpt_down interval.
  395                  */
  396                 if (!(la->la_flags & LLE_STATIC) &&
  397                     time_uptime + la->la_preempt > la->la_expire) {
  398                         renew = 1;
  399                         la->la_preempt--;
  400                 }
  401 
  402                 *lle = la;
  403 
  404                 if (flags & LLE_EXCLUSIVE)
  405                         LLE_WUNLOCK(la);
  406                 else
  407                         LLE_RUNLOCK(la);
  408 
  409                 if (renew == 1)
  410                         arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
  411 
  412                 return (0);
  413         }
  414 
  415         if (la->la_flags & LLE_STATIC) {   /* should not happen! */
  416                 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
  417                     inet_ntoa(SIN(dst)->sin_addr));
  418                 m_freem(m);
  419                 error = EINVAL;
  420                 goto done;
  421         }
  422 
  423         renew = (la->la_asked == 0 || la->la_expire != time_uptime);
  424         if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
  425                 flags |= LLE_EXCLUSIVE;
  426                 LLE_RUNLOCK(la);
  427                 goto retry;
  428         }
  429         /*
  430          * There is an arptab entry, but no ethernet address
  431          * response yet.  Add the mbuf to the list, dropping
  432          * the oldest packet if we have exceeded the system
  433          * setting.
  434          */
  435         if (m != NULL) {
  436                 if (la->la_numheld >= V_arp_maxhold) {
  437                         if (la->la_hold != NULL) {
  438                                 next = la->la_hold->m_nextpkt;
  439                                 m_freem(la->la_hold);
  440                                 la->la_hold = next;
  441                                 la->la_numheld--;
  442                                 ARPSTAT_INC(dropped);
  443                         }
  444                 }
  445                 if (la->la_hold != NULL) {
  446                         curr = la->la_hold;
  447                         while (curr->m_nextpkt != NULL)
  448                                 curr = curr->m_nextpkt;
  449                         curr->m_nextpkt = m;
  450                 } else
  451                         la->la_hold = m;
  452                 la->la_numheld++;
  453                 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
  454                         flags &= ~LLE_EXCLUSIVE;
  455                         LLE_DOWNGRADE(la);
  456                 }
  457 
  458         }
  459         /*
  460          * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
  461          * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
  462          * if we have already sent arp_maxtries ARP requests. Retransmit the
  463          * ARP request, but not faster than one request per second.
  464          */
  465         if (la->la_asked < V_arp_maxtries)
  466                 error = EWOULDBLOCK;    /* First request. */
  467         else
  468                 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
  469                     EHOSTUNREACH : EHOSTDOWN;
  470 
  471         if (renew) {
  472                 int canceled;
  473 
  474                 LLE_ADDREF(la);
  475                 la->la_expire = time_uptime;
  476                 canceled = callout_reset(&la->la_timer, hz * V_arpt_down,
  477                     arptimer, la);
  478                 if (canceled)
  479                         LLE_REMREF(la);
  480                 la->la_asked++;
  481                 LLE_WUNLOCK(la);
  482                 arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
  483                 return (error);
  484         }
  485 done:
  486         if (flags & LLE_EXCLUSIVE)
  487                 LLE_WUNLOCK(la);
  488         else
  489                 LLE_RUNLOCK(la);
  490         return (error);
  491 }
  492 
  493 /*
  494  * Common length and type checks are done here,
  495  * then the protocol-specific routine is called.
  496  */
  497 static void
  498 arpintr(struct mbuf *m)
  499 {
  500         struct arphdr *ar;
  501 
  502         if (m->m_len < sizeof(struct arphdr) &&
  503             ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
  504                 log(LOG_NOTICE, "arp: runt packet -- m_pullup failed\n");
  505                 return;
  506         }
  507         ar = mtod(m, struct arphdr *);
  508 
  509         if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
  510             ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
  511             ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
  512             ntohs(ar->ar_hrd) != ARPHRD_IEEE1394 &&
  513             ntohs(ar->ar_hrd) != ARPHRD_INFINIBAND) {
  514                 log(LOG_NOTICE, "arp: unknown hardware address format (0x%2D)"
  515                     " (from %*D to %*D)\n", (unsigned char *)&ar->ar_hrd, "",
  516                     ETHER_ADDR_LEN, (u_char *)ar_sha(ar), ":",
  517                     ETHER_ADDR_LEN, (u_char *)ar_tha(ar), ":");
  518                 m_freem(m);
  519                 return;
  520         }
  521 
  522         if (m->m_len < arphdr_len(ar)) {
  523                 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
  524                         log(LOG_NOTICE, "arp: runt packet\n");
  525                         m_freem(m);
  526                         return;
  527                 }
  528                 ar = mtod(m, struct arphdr *);
  529         }
  530 
  531         ARPSTAT_INC(received);
  532         switch (ntohs(ar->ar_pro)) {
  533 #ifdef INET
  534         case ETHERTYPE_IP:
  535                 in_arpinput(m);
  536                 return;
  537 #endif
  538         }
  539         m_freem(m);
  540 }
  541 
  542 #ifdef INET
  543 /*
  544  * ARP for Internet protocols on 10 Mb/s Ethernet.
  545  * Algorithm is that given in RFC 826.
  546  * In addition, a sanity check is performed on the sender
  547  * protocol address, to catch impersonators.
  548  * We no longer handle negotiations for use of trailer protocol:
  549  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
  550  * along with IP replies if we wanted trailers sent to us,
  551  * and also sent them in response to IP replies.
  552  * This allowed either end to announce the desire to receive
  553  * trailer packets.
  554  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
  555  * but formerly didn't normally send requests.
  556  */
  557 static int log_arp_wrong_iface = 1;
  558 static int log_arp_movements = 1;
  559 static int log_arp_permanent_modify = 1;
  560 static int allow_multicast = 0;
  561 static struct timeval arp_lastlog;
  562 static int arp_curpps;
  563 static int arp_maxpps = 1;
  564 
  565 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
  566         &log_arp_wrong_iface, 0,
  567         "log arp packets arriving on the wrong interface");
  568 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
  569         &log_arp_movements, 0,
  570         "log arp replies from MACs different than the one in the cache");
  571 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
  572         &log_arp_permanent_modify, 0,
  573         "log arp replies from MACs different than the one in the permanent arp entry");
  574 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW,
  575         &allow_multicast, 0, "accept multicast addresses");
  576 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_log_per_second,
  577         CTLFLAG_RW, &arp_maxpps, 0,
  578         "Maximum number of remotely triggered ARP messages that can be "
  579         "logged per second");
  580 
  581 #define ARP_LOG(pri, ...)       do {                                    \
  582         if (ppsratecheck(&arp_lastlog, &arp_curpps, arp_maxpps))        \
  583                 log((pri), "arp: " __VA_ARGS__);                        \
  584 } while (0)
  585 
  586 static void
  587 in_arpinput(struct mbuf *m)
  588 {
  589         struct arphdr *ah;
  590         struct ifnet *ifp = m->m_pkthdr.rcvif;
  591         struct llentry *la = NULL;
  592         struct rtentry *rt;
  593         struct ifaddr *ifa;
  594         struct in_ifaddr *ia;
  595         struct sockaddr sa;
  596         struct in_addr isaddr, itaddr, myaddr;
  597         u_int8_t *enaddr = NULL;
  598         int op, flags;
  599         int req_len;
  600         int bridged = 0, is_bridge = 0;
  601         int carped;
  602         struct sockaddr_in sin;
  603         sin.sin_len = sizeof(struct sockaddr_in);
  604         sin.sin_family = AF_INET;
  605         sin.sin_addr.s_addr = 0;
  606 
  607         if (ifp->if_bridge)
  608                 bridged = 1;
  609         if (ifp->if_type == IFT_BRIDGE)
  610                 is_bridge = 1;
  611 
  612         req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
  613         if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
  614                 ARP_LOG(LOG_NOTICE, "runt packet -- m_pullup failed\n");
  615                 return;
  616         }
  617 
  618         ah = mtod(m, struct arphdr *);
  619         /*
  620          * ARP is only for IPv4 so we can reject packets with
  621          * a protocol length not equal to an IPv4 address.
  622          */
  623         if (ah->ar_pln != sizeof(struct in_addr)) {
  624                 ARP_LOG(LOG_NOTICE, "requested protocol length != %zu\n",
  625                     sizeof(struct in_addr));
  626                 goto drop;
  627         }
  628 
  629         if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) {
  630                 ARP_LOG(LOG_NOTICE, "%*D is multicast\n",
  631                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":");
  632                 goto drop;
  633         }
  634 
  635         op = ntohs(ah->ar_op);
  636         (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
  637         (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
  638 
  639         if (op == ARPOP_REPLY)
  640                 ARPSTAT_INC(rxreplies);
  641 
  642         /*
  643          * For a bridge, we want to check the address irrespective
  644          * of the receive interface. (This will change slightly
  645          * when we have clusters of interfaces).
  646          */
  647         IN_IFADDR_RLOCK();
  648         LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  649                 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
  650                     ia->ia_ifp == ifp) &&
  651                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr &&
  652                     (ia->ia_ifa.ifa_carp == NULL ||
  653                     (*carp_iamatch_p)(&ia->ia_ifa, &enaddr))) {
  654                         ifa_ref(&ia->ia_ifa);
  655                         IN_IFADDR_RUNLOCK();
  656                         goto match;
  657                 }
  658         }
  659         LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
  660                 if (((bridged && ia->ia_ifp->if_bridge == ifp->if_bridge) ||
  661                     ia->ia_ifp == ifp) &&
  662                     isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  663                         ifa_ref(&ia->ia_ifa);
  664                         IN_IFADDR_RUNLOCK();
  665                         goto match;
  666                 }
  667 
  668 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)                           \
  669   (ia->ia_ifp->if_bridge == ifp->if_softc &&                            \
  670   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&      \
  671   addr == ia->ia_addr.sin_addr.s_addr)
  672         /*
  673          * Check the case when bridge shares its MAC address with
  674          * some of its children, so packets are claimed by bridge
  675          * itself (bridge_input() does it first), but they are really
  676          * meant to be destined to the bridge member.
  677          */
  678         if (is_bridge) {
  679                 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  680                         if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
  681                                 ifa_ref(&ia->ia_ifa);
  682                                 ifp = ia->ia_ifp;
  683                                 IN_IFADDR_RUNLOCK();
  684                                 goto match;
  685                         }
  686                 }
  687         }
  688 #undef BDG_MEMBER_MATCHES_ARP
  689         IN_IFADDR_RUNLOCK();
  690 
  691         /*
  692          * No match, use the first inet address on the receive interface
  693          * as a dummy address for the rest of the function.
  694          */
  695         IF_ADDR_RLOCK(ifp);
  696         TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
  697                 if (ifa->ifa_addr->sa_family == AF_INET &&
  698                     (ifa->ifa_carp == NULL ||
  699                     (*carp_iamatch_p)(ifa, &enaddr))) {
  700                         ia = ifatoia(ifa);
  701                         ifa_ref(ifa);
  702                         IF_ADDR_RUNLOCK(ifp);
  703                         goto match;
  704                 }
  705         IF_ADDR_RUNLOCK(ifp);
  706 
  707         /*
  708          * If bridging, fall back to using any inet address.
  709          */
  710         IN_IFADDR_RLOCK();
  711         if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
  712                 IN_IFADDR_RUNLOCK();
  713                 goto drop;
  714         }
  715         ifa_ref(&ia->ia_ifa);
  716         IN_IFADDR_RUNLOCK();
  717 match:
  718         if (!enaddr)
  719                 enaddr = (u_int8_t *)IF_LLADDR(ifp);
  720         carped = (ia->ia_ifa.ifa_carp != NULL);
  721         myaddr = ia->ia_addr.sin_addr;
  722         ifa_free(&ia->ia_ifa);
  723         if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
  724                 goto drop;      /* it's from me, ignore it. */
  725         if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
  726                 ARP_LOG(LOG_NOTICE, "link address is broadcast for IP address "
  727                     "%s!\n", inet_ntoa(isaddr));
  728                 goto drop;
  729         }
  730         /*
  731          * Warn if another host is using the same IP address, but only if the
  732          * IP address isn't 0.0.0.0, which is used for DHCP only, in which
  733          * case we suppress the warning to avoid false positive complaints of
  734          * potential misconfiguration.
  735          */
  736         if (!bridged && !carped && isaddr.s_addr == myaddr.s_addr &&
  737             myaddr.s_addr != 0) {
  738                 ARP_LOG(LOG_ERR, "%*D is using my IP address %s on %s!\n",
  739                    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  740                    inet_ntoa(isaddr), ifp->if_xname);
  741                 itaddr = myaddr;
  742                 ARPSTAT_INC(dupips);
  743                 goto reply;
  744         }
  745         if (ifp->if_flags & IFF_STATICARP)
  746                 goto reply;
  747 
  748         bzero(&sin, sizeof(sin));
  749         sin.sin_len = sizeof(struct sockaddr_in);
  750         sin.sin_family = AF_INET;
  751         sin.sin_addr = isaddr;
  752         flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
  753         flags |= LLE_EXCLUSIVE;
  754         IF_AFDATA_LOCK(ifp);
  755         la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
  756         IF_AFDATA_UNLOCK(ifp);
  757         if (la != NULL) {
  758                 /* the following is not an error when doing bridging */
  759                 if (!bridged && la->lle_tbl->llt_ifp != ifp) {
  760                         if (log_arp_wrong_iface)
  761                                 ARP_LOG(LOG_WARNING, "%s is on %s "
  762                                     "but got reply from %*D on %s\n",
  763                                     inet_ntoa(isaddr),
  764                                     la->lle_tbl->llt_ifp->if_xname,
  765                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  766                                     ifp->if_xname);
  767                         LLE_WUNLOCK(la);
  768                         goto reply;
  769                 }
  770                 if ((la->la_flags & LLE_VALID) &&
  771                     bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
  772                         if (la->la_flags & LLE_STATIC) {
  773                                 LLE_WUNLOCK(la);
  774                                 if (log_arp_permanent_modify)
  775                                         ARP_LOG(LOG_ERR,
  776                                             "%*D attempts to modify "
  777                                             "permanent entry for %s on %s\n",
  778                                             ifp->if_addrlen,
  779                                             (u_char *)ar_sha(ah), ":",
  780                                             inet_ntoa(isaddr), ifp->if_xname);
  781                                 goto reply;
  782                         }
  783                         if (log_arp_movements) {
  784                                 ARP_LOG(LOG_INFO, "%s moved from %*D "
  785                                     "to %*D on %s\n",
  786                                     inet_ntoa(isaddr),
  787                                     ifp->if_addrlen,
  788                                     (u_char *)&la->ll_addr, ":",
  789                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  790                                     ifp->if_xname);
  791                         }
  792                 }
  793 
  794                 if (ifp->if_addrlen != ah->ar_hln) {
  795                         LLE_WUNLOCK(la);
  796                         ARP_LOG(LOG_WARNING, "from %*D: addr len: new %d, "
  797                             "i/f %d (ignored)\n", ifp->if_addrlen,
  798                             (u_char *) ar_sha(ah), ":", ah->ar_hln,
  799                             ifp->if_addrlen);
  800                         goto drop;
  801                 }
  802                 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
  803                 la->la_flags |= LLE_VALID;
  804 
  805                 EVENTHANDLER_INVOKE(lle_event, la, LLENTRY_RESOLVED);
  806 
  807                 if (!(la->la_flags & LLE_STATIC)) {
  808                         int canceled;
  809 
  810                         LLE_ADDREF(la);
  811                         la->la_expire = time_uptime + V_arpt_keep;
  812                         canceled = callout_reset(&la->la_timer,
  813                             hz * V_arpt_keep, arptimer, la);
  814                         if (canceled)
  815                                 LLE_REMREF(la);
  816                 }
  817                 la->la_asked = 0;
  818                 la->la_preempt = V_arp_maxtries;
  819                 /*
  820                  * The packets are all freed within the call to the output
  821                  * routine.
  822                  *
  823                  * NB: The lock MUST be released before the call to the
  824                  * output routine.
  825                  */
  826                 if (la->la_hold != NULL) {
  827                         struct mbuf *m_hold, *m_hold_next;
  828 
  829                         m_hold = la->la_hold;
  830                         la->la_hold = NULL;
  831                         la->la_numheld = 0;
  832                         memcpy(&sa, L3_ADDR(la), sizeof(sa));
  833                         LLE_WUNLOCK(la);
  834                         for (; m_hold != NULL; m_hold = m_hold_next) {
  835                                 m_hold_next = m_hold->m_nextpkt;
  836                                 m_hold->m_nextpkt = NULL;
  837                                 /* Avoid confusing lower layers. */
  838                                 m_clrprotoflags(m_hold);
  839                                 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
  840                         }
  841                 } else
  842                         LLE_WUNLOCK(la);
  843         }
  844 reply:
  845         if (op != ARPOP_REQUEST)
  846                 goto drop;
  847         ARPSTAT_INC(rxrequests);
  848 
  849         if (itaddr.s_addr == myaddr.s_addr) {
  850                 /* Shortcut.. the receiving interface is the target. */
  851                 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  852                 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  853         } else {
  854                 struct llentry *lle = NULL;
  855 
  856                 sin.sin_addr = itaddr;
  857                 IF_AFDATA_RLOCK(ifp);
  858                 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
  859                 IF_AFDATA_RUNLOCK(ifp);
  860 
  861                 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
  862                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  863                         (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
  864                         LLE_RUNLOCK(lle);
  865                 } else {
  866 
  867                         if (lle != NULL)
  868                                 LLE_RUNLOCK(lle);
  869 
  870                         if (!V_arp_proxyall)
  871                                 goto drop;
  872 
  873                         sin.sin_addr = itaddr;
  874                         /* XXX MRT use table 0 for arp reply  */
  875                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  876                         if (!rt)
  877                                 goto drop;
  878 
  879                         /*
  880                          * Don't send proxies for nodes on the same interface
  881                          * as this one came out of, or we'll get into a fight
  882                          * over who claims what Ether address.
  883                          */
  884                         if (!rt->rt_ifp || rt->rt_ifp == ifp) {
  885                                 RTFREE_LOCKED(rt);
  886                                 goto drop;
  887                         }
  888                         RTFREE_LOCKED(rt);
  889 
  890                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  891                         (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  892 
  893                         /*
  894                          * Also check that the node which sent the ARP packet
  895                          * is on the interface we expect it to be on. This
  896                          * avoids ARP chaos if an interface is connected to the
  897                          * wrong network.
  898                          */
  899                         sin.sin_addr = isaddr;
  900 
  901                         /* XXX MRT use table 0 for arp checks */
  902                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  903                         if (!rt)
  904                                 goto drop;
  905                         if (rt->rt_ifp != ifp) {
  906                                 ARP_LOG(LOG_INFO, "proxy: ignoring request"
  907                                     " from %s via %s, expecting %s\n",
  908                                     inet_ntoa(isaddr), ifp->if_xname,
  909                                     rt->rt_ifp->if_xname);
  910                                 RTFREE_LOCKED(rt);
  911                                 goto drop;
  912                         }
  913                         RTFREE_LOCKED(rt);
  914 
  915 #ifdef DEBUG_PROXY
  916                         printf("arp: proxying for %s\n", inet_ntoa(itaddr));
  917 #endif
  918                 }
  919         }
  920 
  921         if (itaddr.s_addr == myaddr.s_addr &&
  922             IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
  923                 /* RFC 3927 link-local IPv4; always reply by broadcast. */
  924 #ifdef DEBUG_LINKLOCAL
  925                 printf("arp: sending reply for link-local addr %s\n",
  926                     inet_ntoa(itaddr));
  927 #endif
  928                 m->m_flags |= M_BCAST;
  929                 m->m_flags &= ~M_MCAST;
  930         } else {
  931                 /* default behaviour; never reply by broadcast. */
  932                 m->m_flags &= ~(M_BCAST|M_MCAST);
  933         }
  934         (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
  935         (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
  936         ah->ar_op = htons(ARPOP_REPLY);
  937         ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
  938         m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
  939         m->m_pkthdr.len = m->m_len;
  940         m->m_pkthdr.rcvif = NULL;
  941         sa.sa_family = AF_ARP;
  942         sa.sa_len = 2;
  943         m_clrprotoflags(m);     /* Avoid confusing lower layers. */
  944         (*ifp->if_output)(ifp, m, &sa, NULL);
  945         ARPSTAT_INC(txreplies);
  946         return;
  947 
  948 drop:
  949         m_freem(m);
  950 }
  951 #endif
  952 
  953 /*
  954  * Handle the garp_rexmit_count. Like sysctl_handle_int(), but limits the range
  955  * of valid values.
  956  */
  957 static int
  958 sysctl_garp_rexmit(SYSCTL_HANDLER_ARGS)
  959 {
  960         int error;
  961         int rexmit_count = *(int *)arg1;
  962 
  963         error = sysctl_handle_int(oidp, &rexmit_count, 0, req);
  964 
  965         /* Enforce limits on any new value that may have been set. */
  966         if (!error && req->newptr) {
  967                 /* A new value was set. */
  968                 if (rexmit_count < 0) {
  969                         rexmit_count = 0;
  970                 } else if (rexmit_count > MAX_GARP_RETRANSMITS) {
  971                         rexmit_count = MAX_GARP_RETRANSMITS;
  972                 }
  973                 *(int *)arg1 = rexmit_count;
  974         }
  975 
  976         return (error);
  977 }
  978 
  979 /*
  980  * Retransmit a Gratuitous ARP (GARP) and, if necessary, schedule a callout to
  981  * retransmit it again. A pending callout owns a reference to the ifa.
  982  */
  983 static void
  984 garp_rexmit(void *arg)
  985 {
  986         struct in_ifaddr *ia = arg;
  987 
  988         if (callout_pending(&ia->ia_garp_timer) ||
  989             !callout_active(&ia->ia_garp_timer)) {
  990                 IFA_UNLOCK(&ia->ia_ifa);
  991                 ifa_free(&ia->ia_ifa);
  992                 return;
  993         }
  994 
  995         /*
  996          * Drop ifa lock while the ARP request is generated.
  997          */
  998         IFA_UNLOCK(&ia->ia_ifa);
  999 
 1000         arprequest(ia->ia_ifa.ifa_ifp, &IA_SIN(ia)->sin_addr,
 1001             &IA_SIN(ia)->sin_addr, IF_LLADDR(ia->ia_ifa.ifa_ifp));
 1002 
 1003         /*
 1004          * Increment the count of retransmissions. If the count has reached the
 1005          * maximum value, stop sending the GARP packets. Otherwise, schedule
 1006          * the callout to retransmit another GARP packet.
 1007          */
 1008         ++ia->ia_garp_count;
 1009         if (ia->ia_garp_count >= garp_rexmit_count) {
 1010                 ifa_free(&ia->ia_ifa);
 1011         } else {
 1012                 int rescheduled;
 1013                 IFA_LOCK(&ia->ia_ifa);
 1014                 rescheduled = callout_reset(&ia->ia_garp_timer,
 1015                     (1 << ia->ia_garp_count) * hz,
 1016                     garp_rexmit, ia);
 1017                 IFA_UNLOCK(&ia->ia_ifa);
 1018                 if (rescheduled) {
 1019                         ifa_free(&ia->ia_ifa);
 1020                 }
 1021         }
 1022 }
 1023 
 1024 /*
 1025  * Start the GARP retransmit timer.
 1026  *
 1027  * A single GARP is always transmitted when an IPv4 address is added
 1028  * to an interface and that is usually sufficient. However, in some
 1029  * circumstances, such as when a shared address is passed between
 1030  * cluster nodes, this single GARP may occasionally be dropped or
 1031  * lost. This can lead to neighbors on the network link working with a
 1032  * stale ARP cache and sending packets destined for that address to
 1033  * the node that previously owned the address, which may not respond.
 1034  *
 1035  * To avoid this situation, GARP retransmits can be enabled by setting
 1036  * the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
 1037  * than zero. The setting represents the maximum number of
 1038  * retransmissions. The interval between retransmissions is calculated
 1039  * using an exponential backoff algorithm, doubling each time, so the
 1040  * retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds).
 1041  */
 1042 static void
 1043 garp_timer_start(struct ifaddr *ifa)
 1044 {
 1045         struct in_ifaddr *ia = (struct in_ifaddr *) ifa;
 1046 
 1047         IFA_LOCK(ifa);
 1048         ia->ia_garp_count = 0;
 1049         if (callout_reset(&ia->ia_garp_timer, (1 << ia->ia_garp_count) * hz,
 1050             garp_rexmit, ia) == 0) {
 1051                 ifa_ref(ifa);
 1052         }
 1053         IFA_UNLOCK(ifa);
 1054 }
 1055 
 1056 void
 1057 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
 1058 {
 1059         struct llentry *lle;
 1060 
 1061         if (ifa->ifa_carp != NULL)
 1062                 return;
 1063 
 1064         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
 1065                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
 1066                                 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
 1067                 if (garp_rexmit_count > 0) {
 1068                         garp_timer_start(ifa);
 1069                 }
 1070 
 1071                 /*
 1072                  * interface address is considered static entry
 1073                  * because the output of the arp utility shows
 1074                  * that L2 entry as permanent
 1075                  */
 1076                 IF_AFDATA_LOCK(ifp);
 1077                 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
 1078                                  (struct sockaddr *)IA_SIN(ifa));
 1079                 IF_AFDATA_UNLOCK(ifp);
 1080                 if (lle == NULL)
 1081                         log(LOG_INFO, "arp_ifinit: cannot create arp "
 1082                             "entry for interface address\n");
 1083                 else
 1084                         LLE_RUNLOCK(lle);
 1085         }
 1086         ifa->ifa_rtrequest = NULL;
 1087 }
 1088 
 1089 void
 1090 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
 1091 {
 1092         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
 1093                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
 1094                                 &IA_SIN(ifa)->sin_addr, enaddr);
 1095         ifa->ifa_rtrequest = NULL;
 1096 }
 1097 
 1098 static void
 1099 arp_init(void)
 1100 {
 1101 
 1102         netisr_register(&arp_nh);
 1103 }
 1104 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);

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