The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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("$FreeBSD$");
   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 #if defined(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) ((struct sockaddr_in *)s)
   77 #define SDL(s) ((struct sockaddr_dl *)s)
   78 
   79 SYSCTL_DECL(_net_link_ether);
   80 SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
   81 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_DEFINE(struct arpstat, arpstat);  /* ARP statistics, see if_arp.h */
   93 
   94 static VNET_DEFINE(int, arp_maxhold) = 1;
   95 
   96 #define V_arpt_keep             VNET(arpt_keep)
   97 #define V_arpt_down             VNET(arpt_down)
   98 #define V_arp_maxtries          VNET(arp_maxtries)
   99 #define V_arp_proxyall          VNET(arp_proxyall)
  100 #define V_arpstat               VNET(arpstat)
  101 #define V_arp_maxhold           VNET(arp_maxhold)
  102 
  103 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
  104         &VNET_NAME(arpt_keep), 0,
  105         "ARP entry lifetime in seconds");
  106 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
  107         &VNET_NAME(arp_maxtries), 0,
  108         "ARP resolution attempts before returning error");
  109 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
  110         &VNET_NAME(useloopback), 0,
  111         "Use the loopback interface for local traffic");
  112 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
  113         &VNET_NAME(arp_proxyall), 0,
  114         "Enable proxy ARP for all suitable requests");
  115 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, wait, CTLFLAG_RW,
  116         &VNET_NAME(arpt_down), 0,
  117         "Incomplete ARP entry lifetime in seconds");
  118 SYSCTL_VNET_STRUCT(_net_link_ether_arp, OID_AUTO, stats, CTLFLAG_RW,
  119         &VNET_NAME(arpstat), arpstat,
  120         "ARP statistics (struct arpstat, net/if_arp.h)");
  121 SYSCTL_VNET_INT(_net_link_ether_inet, OID_AUTO, maxhold, CTLFLAG_RW,
  122         &VNET_NAME(arp_maxhold), 0, 
  123         "Number of packets to hold per ARP entry");
  124 
  125 static void     arp_init(void);
  126 void            arprequest(struct ifnet *,
  127                         struct in_addr *, struct in_addr *, u_char *);
  128 static void     arpintr(struct mbuf *);
  129 static void     arptimer(void *);
  130 #ifdef INET
  131 static void     in_arpinput(struct mbuf *);
  132 #endif
  133 
  134 static const struct netisr_handler arp_nh = {
  135         .nh_name = "arp",
  136         .nh_handler = arpintr,
  137         .nh_proto = NETISR_ARP,
  138         .nh_policy = NETISR_POLICY_SOURCE,
  139 };
  140 
  141 #ifdef AF_INET
  142 void arp_ifscrub(struct ifnet *ifp, uint32_t addr);
  143 
  144 /*
  145  * called by in_ifscrub to remove entry from the table when
  146  * the interface goes away
  147  */
  148 void
  149 arp_ifscrub(struct ifnet *ifp, uint32_t addr)
  150 {
  151         struct sockaddr_in addr4;
  152 
  153         bzero((void *)&addr4, sizeof(addr4));
  154         addr4.sin_len    = sizeof(addr4);
  155         addr4.sin_family = AF_INET;
  156         addr4.sin_addr.s_addr = addr;
  157         IF_AFDATA_LOCK(ifp);
  158         lla_lookup(LLTABLE(ifp), (LLE_DELETE | LLE_IFADDR),
  159             (struct sockaddr *)&addr4);
  160         IF_AFDATA_UNLOCK(ifp);
  161 }
  162 #endif
  163 
  164 /*
  165  * Timeout routine.  Age arp_tab entries periodically.
  166  */
  167 static void
  168 arptimer(void *arg)
  169 {
  170         struct llentry *lle = (struct llentry *)arg;
  171         struct ifnet *ifp;
  172         size_t pkts_dropped;
  173 
  174         if (lle->la_flags & LLE_STATIC) {
  175                 LLE_WUNLOCK(lle);
  176                 return;
  177         }
  178 
  179         ifp = lle->lle_tbl->llt_ifp;
  180         CURVNET_SET(ifp->if_vnet);
  181 
  182         callout_stop(&lle->la_timer);
  183 
  184         /* XXX: LOR avoidance. We still have ref on lle. */
  185         LLE_WUNLOCK(lle);
  186         IF_AFDATA_LOCK(ifp);
  187         LLE_WLOCK(lle);
  188 
  189         LLE_REMREF(lle);
  190         pkts_dropped = llentry_free(lle);
  191         IF_AFDATA_UNLOCK(ifp);
  192         ARPSTAT_ADD(dropped, pkts_dropped);
  193         ARPSTAT_INC(timeouts);
  194         CURVNET_RESTORE();
  195 }
  196 
  197 /*
  198  * Broadcast an ARP request. Caller specifies:
  199  *      - arp header source ip address
  200  *      - arp header target ip address
  201  *      - arp header source ethernet address
  202  */
  203 void
  204 arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr  *tip,
  205     u_char *enaddr)
  206 {
  207         struct mbuf *m;
  208         struct arphdr *ah;
  209         struct sockaddr sa;
  210 
  211         if (sip == NULL) {
  212                 /* XXX don't believe this can happen (or explain why) */
  213                 /*
  214                  * The caller did not supply a source address, try to find
  215                  * a compatible one among those assigned to this interface.
  216                  */
  217                 struct ifaddr *ifa;
  218 
  219                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  220                         if (!ifa->ifa_addr ||
  221                             ifa->ifa_addr->sa_family != AF_INET)
  222                                 continue;
  223                         sip = &SIN(ifa->ifa_addr)->sin_addr;
  224                         if (0 == ((sip->s_addr ^ tip->s_addr) &
  225                             SIN(ifa->ifa_netmask)->sin_addr.s_addr) )
  226                                 break;  /* found it. */
  227                 }
  228                 if (sip == NULL) {  
  229                         printf("%s: cannot find matching address\n", __func__);
  230                         return;
  231                 }
  232         }
  233 
  234         if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
  235                 return;
  236         m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
  237                 2*ifp->if_data.ifi_addrlen;
  238         m->m_pkthdr.len = m->m_len;
  239         MH_ALIGN(m, m->m_len);
  240         ah = mtod(m, struct arphdr *);
  241         bzero((caddr_t)ah, m->m_len);
  242 #ifdef MAC
  243         mac_netinet_arp_send(ifp, m);
  244 #endif
  245         ah->ar_pro = htons(ETHERTYPE_IP);
  246         ah->ar_hln = ifp->if_addrlen;           /* hardware address length */
  247         ah->ar_pln = sizeof(struct in_addr);    /* protocol address length */
  248         ah->ar_op = htons(ARPOP_REQUEST);
  249         bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
  250         bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
  251         bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
  252         sa.sa_family = AF_ARP;
  253         sa.sa_len = 2;
  254         m->m_flags |= M_BCAST;
  255         (*ifp->if_output)(ifp, m, &sa, NULL);
  256         ARPSTAT_INC(txrequests);
  257 }
  258 
  259 /*
  260  * Resolve an IP address into an ethernet address.
  261  * On input:
  262  *    ifp is the interface we use
  263  *    rt0 is the route to the final destination (possibly useless)
  264  *    m is the mbuf. May be NULL if we don't have a packet.
  265  *    dst is the next hop,
  266  *    desten is where we want the address.
  267  *
  268  * On success, desten is filled in and the function returns 0;
  269  * If the packet must be held pending resolution, we return EWOULDBLOCK
  270  * On other errors, we return the corresponding error code.
  271  * Note that m_freem() handles NULL.
  272  */
  273 int
  274 arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
  275         struct sockaddr *dst, u_char *desten, struct llentry **lle)
  276 {
  277         struct llentry *la = 0;
  278         u_int flags = 0;
  279         struct mbuf *curr = NULL;
  280         struct mbuf *next = NULL;
  281         int error, renew;
  282 
  283         *lle = NULL;
  284         if (m != NULL) {
  285                 if (m->m_flags & M_BCAST) {
  286                         /* broadcast */
  287                         (void)memcpy(desten,
  288                             ifp->if_broadcastaddr, ifp->if_addrlen);
  289                         return (0);
  290                 }
  291                 if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
  292                         /* multicast */
  293                         ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
  294                         return (0);
  295                 }
  296         }
  297         /* XXXXX
  298          */
  299 retry:
  300         IF_AFDATA_RLOCK(ifp);   
  301         la = lla_lookup(LLTABLE(ifp), flags, dst);
  302         IF_AFDATA_RUNLOCK(ifp); 
  303         if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
  304             && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {          
  305                 flags |= (LLE_CREATE | LLE_EXCLUSIVE);
  306                 IF_AFDATA_WLOCK(ifp);   
  307                 la = lla_lookup(LLTABLE(ifp), flags, dst);
  308                 IF_AFDATA_WUNLOCK(ifp); 
  309         }
  310         if (la == NULL) {
  311                 if (flags & LLE_CREATE)
  312                         log(LOG_DEBUG,
  313                             "arpresolve: can't allocate llinfo for %s\n",
  314                             inet_ntoa(SIN(dst)->sin_addr));
  315                 m_freem(m);
  316                 return (EINVAL);
  317         } 
  318 
  319         if ((la->la_flags & LLE_VALID) &&
  320             ((la->la_flags & LLE_STATIC) || la->la_expire > time_second)) {
  321                 bcopy(&la->ll_addr, desten, ifp->if_addrlen);
  322                 /*
  323                  * If entry has an expiry time and it is approaching,
  324                  * see if we need to send an ARP request within this
  325                  * arpt_down interval.
  326                  */
  327                 if (!(la->la_flags & LLE_STATIC) &&
  328                     time_second + la->la_preempt > la->la_expire) {
  329                         arprequest(ifp, NULL,
  330                             &SIN(dst)->sin_addr, IF_LLADDR(ifp));
  331 
  332                         la->la_preempt--;
  333                 }
  334                 
  335                 *lle = la;
  336                 error = 0;
  337                 goto done;
  338         } 
  339                             
  340         if (la->la_flags & LLE_STATIC) {   /* should not happen! */
  341                 log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
  342                     inet_ntoa(SIN(dst)->sin_addr));
  343                 m_freem(m);
  344                 error = EINVAL;
  345                 goto done;
  346         }
  347 
  348         renew = (la->la_asked == 0 || la->la_expire != time_second);
  349         if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
  350                 flags |= LLE_EXCLUSIVE;
  351                 LLE_RUNLOCK(la);
  352                 goto retry;
  353         }
  354         /*
  355          * There is an arptab entry, but no ethernet address
  356          * response yet.  Add the mbuf to the list, dropping
  357          * the oldest packet if we have exceeded the system
  358          * setting.
  359          */
  360         if (m != NULL) {
  361                 if (la->la_numheld >= V_arp_maxhold) {
  362                         if (la->la_hold != NULL) {
  363                                 next = la->la_hold->m_nextpkt;
  364                                 m_freem(la->la_hold);
  365                                 la->la_hold = next;
  366                                 la->la_numheld--;
  367                                 ARPSTAT_INC(dropped);
  368                         }
  369                 } 
  370                 if (la->la_hold != NULL) {
  371                         curr = la->la_hold;
  372                         while (curr->m_nextpkt != NULL)
  373                                 curr = curr->m_nextpkt;
  374                         curr->m_nextpkt = m;
  375                 } else 
  376                         la->la_hold = m;
  377                 la->la_numheld++;
  378                 if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
  379                         flags &= ~LLE_EXCLUSIVE;
  380                         LLE_DOWNGRADE(la);
  381                 }
  382                 
  383         }
  384         /*
  385          * Return EWOULDBLOCK if we have tried less than arp_maxtries. It
  386          * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
  387          * if we have already sent arp_maxtries ARP requests. Retransmit the
  388          * ARP request, but not faster than one request per second.
  389          */
  390         if (la->la_asked < V_arp_maxtries)
  391                 error = EWOULDBLOCK;    /* First request. */
  392         else
  393                 error = rt0 != NULL && (rt0->rt_flags & RTF_GATEWAY) ?
  394                     EHOSTUNREACH : EHOSTDOWN;
  395 
  396         if (renew) {
  397                 int canceled;
  398 
  399                 LLE_ADDREF(la);
  400                 la->la_expire = time_second;
  401                 canceled = callout_reset(&la->la_timer, hz * V_arpt_down,
  402                     arptimer, la);
  403                 if (canceled)
  404                         LLE_REMREF(la);
  405                 la->la_asked++;
  406                 LLE_WUNLOCK(la);
  407                 arprequest(ifp, NULL, &SIN(dst)->sin_addr,
  408                     IF_LLADDR(ifp));
  409                 return (error);
  410         }
  411 done:
  412         if (flags & LLE_EXCLUSIVE)
  413                 LLE_WUNLOCK(la);
  414         else
  415                 LLE_RUNLOCK(la);
  416         return (error);
  417 }
  418 
  419 /*
  420  * Common length and type checks are done here,
  421  * then the protocol-specific routine is called.
  422  */
  423 static void
  424 arpintr(struct mbuf *m)
  425 {
  426         struct arphdr *ar;
  427 
  428         if (m->m_len < sizeof(struct arphdr) &&
  429             ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
  430                 log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
  431                 return;
  432         }
  433         ar = mtod(m, struct arphdr *);
  434 
  435         if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
  436             ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
  437             ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
  438             ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
  439                 log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
  440                     (unsigned char *)&ar->ar_hrd, "");
  441                 m_freem(m);
  442                 return;
  443         }
  444 
  445         if (m->m_len < arphdr_len(ar)) {
  446                 if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
  447                         log(LOG_ERR, "arp: runt packet\n");
  448                         m_freem(m);
  449                         return;
  450                 }
  451                 ar = mtod(m, struct arphdr *);
  452         }
  453 
  454         ARPSTAT_INC(received);
  455         switch (ntohs(ar->ar_pro)) {
  456 #ifdef INET
  457         case ETHERTYPE_IP:
  458                 in_arpinput(m);
  459                 return;
  460 #endif
  461         }
  462         m_freem(m);
  463 }
  464 
  465 #ifdef INET
  466 /*
  467  * ARP for Internet protocols on 10 Mb/s Ethernet.
  468  * Algorithm is that given in RFC 826.
  469  * In addition, a sanity check is performed on the sender
  470  * protocol address, to catch impersonators.
  471  * We no longer handle negotiations for use of trailer protocol:
  472  * Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
  473  * along with IP replies if we wanted trailers sent to us,
  474  * and also sent them in response to IP replies.
  475  * This allowed either end to announce the desire to receive
  476  * trailer packets.
  477  * We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
  478  * but formerly didn't normally send requests.
  479  */
  480 static int log_arp_wrong_iface = 1;
  481 static int log_arp_movements = 1;
  482 static int log_arp_permanent_modify = 1;
  483 
  484 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
  485         &log_arp_wrong_iface, 0,
  486         "log arp packets arriving on the wrong interface");
  487 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
  488         &log_arp_movements, 0,
  489         "log arp replies from MACs different than the one in the cache");
  490 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
  491         &log_arp_permanent_modify, 0,
  492         "log arp replies from MACs different than the one in the permanent arp entry");
  493 
  494 
  495 static void
  496 in_arpinput(struct mbuf *m)
  497 {
  498         struct arphdr *ah;
  499         struct ifnet *ifp = m->m_pkthdr.rcvif;
  500         struct llentry *la = NULL;
  501         struct rtentry *rt;
  502         struct ifaddr *ifa;
  503         struct in_ifaddr *ia;
  504         struct sockaddr sa;
  505         struct in_addr isaddr, itaddr, myaddr;
  506         u_int8_t *enaddr = NULL;
  507         int op, flags;
  508         int req_len;
  509         int bridged = 0, is_bridge = 0;
  510         int carp_match = 0;
  511         struct sockaddr_in sin;
  512         sin.sin_len = sizeof(struct sockaddr_in);
  513         sin.sin_family = AF_INET;
  514         sin.sin_addr.s_addr = 0;
  515 
  516         if (ifp->if_bridge)
  517                 bridged = 1;
  518         if (ifp->if_type == IFT_BRIDGE)
  519                 is_bridge = 1;
  520 
  521         req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
  522         if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
  523                 log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
  524                 return;
  525         }
  526 
  527         ah = mtod(m, struct arphdr *);
  528         op = ntohs(ah->ar_op);
  529         (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
  530         (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
  531 
  532         if (op == ARPOP_REPLY)
  533                 ARPSTAT_INC(rxreplies);
  534 
  535         /*
  536          * For a bridge, we want to check the address irrespective
  537          * of the receive interface. (This will change slightly
  538          * when we have clusters of interfaces).
  539          * If the interface does not match, but the recieving interface
  540          * is part of carp, we call carp_iamatch to see if this is a
  541          * request for the virtual host ip.
  542          * XXX: This is really ugly!
  543          */
  544         IN_IFADDR_RLOCK();
  545         LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  546                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
  547                     ia->ia_ifp == ifp) &&
  548                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  549                         ifa_ref(&ia->ia_ifa);
  550                         IN_IFADDR_RUNLOCK();
  551                         goto match;
  552                 }
  553                 if (ifp->if_carp != NULL &&
  554                     (*carp_iamatch_p)(ifp, ia, &isaddr, &enaddr) &&
  555                     itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  556                         carp_match = 1;
  557                         ifa_ref(&ia->ia_ifa);
  558                         IN_IFADDR_RUNLOCK();
  559                         goto match;
  560                 }
  561         }
  562         LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
  563                 if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
  564                     ia->ia_ifp == ifp) &&
  565                     isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
  566                         ifa_ref(&ia->ia_ifa);
  567                         IN_IFADDR_RUNLOCK();
  568                         goto match;
  569                 }
  570 
  571 #define BDG_MEMBER_MATCHES_ARP(addr, ifp, ia)                           \
  572   (ia->ia_ifp->if_bridge == ifp->if_softc &&                            \
  573   !bcmp(IF_LLADDR(ia->ia_ifp), IF_LLADDR(ifp), ifp->if_addrlen) &&      \
  574   addr == ia->ia_addr.sin_addr.s_addr)
  575         /*
  576          * Check the case when bridge shares its MAC address with
  577          * some of its children, so packets are claimed by bridge
  578          * itself (bridge_input() does it first), but they are really
  579          * meant to be destined to the bridge member.
  580          */
  581         if (is_bridge) {
  582                 LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
  583                         if (BDG_MEMBER_MATCHES_ARP(itaddr.s_addr, ifp, ia)) {
  584                                 ifa_ref(&ia->ia_ifa);
  585                                 ifp = ia->ia_ifp;
  586                                 IN_IFADDR_RUNLOCK();
  587                                 goto match;
  588                         }
  589                 }
  590         }
  591 #undef BDG_MEMBER_MATCHES_ARP
  592         IN_IFADDR_RUNLOCK();
  593 
  594         /*
  595          * No match, use the first inet address on the receive interface
  596          * as a dummy address for the rest of the function.
  597          */
  598         IF_ADDR_RLOCK(ifp);
  599         TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
  600                 if (ifa->ifa_addr->sa_family == AF_INET) {
  601                         ia = ifatoia(ifa);
  602                         ifa_ref(ifa);
  603                         IF_ADDR_RUNLOCK(ifp);
  604                         goto match;
  605                 }
  606         IF_ADDR_RUNLOCK(ifp);
  607 
  608         /*
  609          * If bridging, fall back to using any inet address.
  610          */
  611         IN_IFADDR_RLOCK();
  612         if (!bridged || (ia = TAILQ_FIRST(&V_in_ifaddrhead)) == NULL) {
  613                 IN_IFADDR_RUNLOCK();
  614                 goto drop;
  615         }
  616         ifa_ref(&ia->ia_ifa);
  617         IN_IFADDR_RUNLOCK();
  618 match:
  619         if (!enaddr)
  620                 enaddr = (u_int8_t *)IF_LLADDR(ifp);
  621         myaddr = ia->ia_addr.sin_addr;
  622         ifa_free(&ia->ia_ifa);
  623         if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
  624                 goto drop;      /* it's from me, ignore it. */
  625         if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
  626                 log(LOG_ERR,
  627                     "arp: link address is broadcast for IP address %s!\n",
  628                     inet_ntoa(isaddr));
  629                 goto drop;
  630         }
  631         /*
  632          * Warn if another host is using the same IP address, but only if the
  633          * IP address isn't 0.0.0.0, which is used for DHCP only, in which
  634          * case we suppress the warning to avoid false positive complaints of
  635          * potential misconfiguration.
  636          */
  637         if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
  638                 log(LOG_ERR,
  639                    "arp: %*D is using my IP address %s on %s!\n",
  640                    ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  641                    inet_ntoa(isaddr), ifp->if_xname);
  642                 itaddr = myaddr;
  643                 ARPSTAT_INC(dupips);
  644                 goto reply;
  645         }
  646         if (ifp->if_flags & IFF_STATICARP)
  647                 goto reply;
  648 
  649         bzero(&sin, sizeof(sin));
  650         sin.sin_len = sizeof(struct sockaddr_in);
  651         sin.sin_family = AF_INET;
  652         sin.sin_addr = isaddr;
  653         flags = (itaddr.s_addr == myaddr.s_addr) ? LLE_CREATE : 0;
  654         flags |= LLE_EXCLUSIVE;
  655         IF_AFDATA_LOCK(ifp); 
  656         la = lla_lookup(LLTABLE(ifp), flags, (struct sockaddr *)&sin);
  657         IF_AFDATA_UNLOCK(ifp);
  658         if (la != NULL) {
  659                 /* the following is not an error when doing bridging */
  660                 if (!bridged && la->lle_tbl->llt_ifp != ifp && !carp_match) {
  661                         if (log_arp_wrong_iface)
  662                                 log(LOG_ERR, "arp: %s is on %s "
  663                                     "but got reply from %*D on %s\n",
  664                                     inet_ntoa(isaddr),
  665                                     la->lle_tbl->llt_ifp->if_xname,
  666                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  667                                     ifp->if_xname);
  668                         LLE_WUNLOCK(la);
  669                         goto reply;
  670                 }
  671                 if ((la->la_flags & LLE_VALID) &&
  672                     bcmp(ar_sha(ah), &la->ll_addr, ifp->if_addrlen)) {
  673                         if (la->la_flags & LLE_STATIC) {
  674                                 LLE_WUNLOCK(la);
  675                                 if (log_arp_permanent_modify)
  676                                         log(LOG_ERR,
  677                                             "arp: %*D attempts to modify "
  678                                             "permanent entry for %s on %s\n",
  679                                             ifp->if_addrlen,
  680                                             (u_char *)ar_sha(ah), ":",
  681                                             inet_ntoa(isaddr), ifp->if_xname);
  682                                 goto reply;
  683                         }
  684                         if (log_arp_movements) {
  685                                 log(LOG_INFO, "arp: %s moved from %*D "
  686                                     "to %*D on %s\n",
  687                                     inet_ntoa(isaddr),
  688                                     ifp->if_addrlen,
  689                                     (u_char *)&la->ll_addr, ":",
  690                                     ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
  691                                     ifp->if_xname);
  692                         }
  693                 }
  694                     
  695                 if (ifp->if_addrlen != ah->ar_hln) {
  696                         LLE_WUNLOCK(la);
  697                         log(LOG_WARNING,
  698                             "arp from %*D: addr len: new %d, i/f %d (ignored)",
  699                             ifp->if_addrlen, (u_char *) ar_sha(ah), ":",
  700                             ah->ar_hln, ifp->if_addrlen);
  701                         goto reply;
  702                 }
  703                 (void)memcpy(&la->ll_addr, ar_sha(ah), ifp->if_addrlen);
  704                 la->la_flags |= LLE_VALID;
  705 
  706                 if (!(la->la_flags & LLE_STATIC)) {
  707                         int canceled;
  708 
  709                         LLE_ADDREF(la);
  710                         la->la_expire = time_second + V_arpt_keep;
  711                         canceled = callout_reset(&la->la_timer,
  712                             hz * V_arpt_keep, arptimer, la);
  713                         if (canceled)
  714                                 LLE_REMREF(la);
  715                 }
  716                 la->la_asked = 0;
  717                 la->la_preempt = V_arp_maxtries;
  718                 /* 
  719                  * The packets are all freed within the call to the output
  720                  * routine.
  721                  *
  722                  * NB: The lock MUST be released before the call to the
  723                  * output routine.
  724                  */
  725                 if (la->la_hold != NULL) {
  726                         struct mbuf *m_hold, *m_hold_next;
  727 
  728                         m_hold = la->la_hold;
  729                         la->la_hold = NULL;
  730                         la->la_numheld = 0;
  731                         memcpy(&sa, L3_ADDR(la), sizeof(sa));
  732                         LLE_WUNLOCK(la);
  733                         for (; m_hold != NULL; m_hold = m_hold_next) {
  734                                 m_hold_next = m_hold->m_nextpkt;
  735                                 m_hold->m_nextpkt = NULL;
  736                                 (*ifp->if_output)(ifp, m_hold, &sa, NULL);
  737                         }
  738                 } else
  739                         LLE_WUNLOCK(la);
  740         } /* end of FIB loop */
  741 reply:
  742         if (op != ARPOP_REQUEST)
  743                 goto drop;
  744         ARPSTAT_INC(rxrequests);
  745 
  746         if (itaddr.s_addr == myaddr.s_addr) {
  747                 /* Shortcut.. the receiving interface is the target. */
  748                 (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  749                 (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  750         } else {
  751                 struct llentry *lle = NULL;
  752 
  753                 sin.sin_addr = itaddr;
  754                 IF_AFDATA_LOCK(ifp); 
  755                 lle = lla_lookup(LLTABLE(ifp), 0, (struct sockaddr *)&sin);
  756                 IF_AFDATA_UNLOCK(ifp);
  757 
  758                 if ((lle != NULL) && (lle->la_flags & LLE_PUB)) {
  759                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  760                         (void)memcpy(ar_sha(ah), &lle->ll_addr, ah->ar_hln);
  761                         LLE_RUNLOCK(lle);
  762                 } else {
  763 
  764                         if (lle != NULL)
  765                                 LLE_RUNLOCK(lle);
  766 
  767                         if (!V_arp_proxyall)
  768                                 goto drop;
  769                         
  770                         sin.sin_addr = itaddr;
  771                         /* XXX MRT use table 0 for arp reply  */
  772                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  773                         if (!rt)
  774                                 goto drop;
  775 
  776                         /*
  777                          * Don't send proxies for nodes on the same interface
  778                          * as this one came out of, or we'll get into a fight
  779                          * over who claims what Ether address.
  780                          */
  781                         if (!rt->rt_ifp || rt->rt_ifp == ifp) {
  782                                 RTFREE_LOCKED(rt);
  783                                 goto drop;
  784                         }
  785                         RTFREE_LOCKED(rt);
  786 
  787                         (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
  788                         (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
  789 
  790                         /*
  791                          * Also check that the node which sent the ARP packet
  792                          * is on the interface we expect it to be on. This
  793                          * avoids ARP chaos if an interface is connected to the
  794                          * wrong network.
  795                          */
  796                         sin.sin_addr = isaddr;
  797                         
  798                         /* XXX MRT use table 0 for arp checks */
  799                         rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
  800                         if (!rt)
  801                                 goto drop;
  802                         if (rt->rt_ifp != ifp) {
  803                                 log(LOG_INFO, "arp_proxy: ignoring request"
  804                                     " from %s via %s, expecting %s\n",
  805                                     inet_ntoa(isaddr), ifp->if_xname,
  806                                     rt->rt_ifp->if_xname);
  807                                 RTFREE_LOCKED(rt);
  808                                 goto drop;
  809                         }
  810                         RTFREE_LOCKED(rt);
  811 
  812 #ifdef DEBUG_PROXY
  813                         printf("arp: proxying for %s\n",
  814                                inet_ntoa(itaddr));
  815 #endif
  816                 }
  817         }
  818 
  819         if (itaddr.s_addr == myaddr.s_addr &&
  820             IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
  821                 /* RFC 3927 link-local IPv4; always reply by broadcast. */
  822 #ifdef DEBUG_LINKLOCAL
  823                 printf("arp: sending reply for link-local addr %s\n",
  824                     inet_ntoa(itaddr));
  825 #endif
  826                 m->m_flags |= M_BCAST;
  827                 m->m_flags &= ~M_MCAST;
  828         } else {
  829                 /* default behaviour; never reply by broadcast. */
  830                 m->m_flags &= ~(M_BCAST|M_MCAST);
  831         }
  832         (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
  833         (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
  834         ah->ar_op = htons(ARPOP_REPLY);
  835         ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
  836         m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);   
  837         m->m_pkthdr.len = m->m_len;   
  838         m->m_pkthdr.rcvif = NULL;
  839         sa.sa_family = AF_ARP;
  840         sa.sa_len = 2;
  841         (*ifp->if_output)(ifp, m, &sa, NULL);
  842         ARPSTAT_INC(txreplies);
  843         return;
  844 
  845 drop:
  846         m_freem(m);
  847 }
  848 #endif
  849 
  850 void
  851 arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
  852 {
  853         struct llentry *lle;
  854 
  855         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) {
  856                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  857                                 &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
  858                 /* 
  859                  * interface address is considered static entry
  860                  * because the output of the arp utility shows
  861                  * that L2 entry as permanent
  862                  */
  863                 IF_AFDATA_LOCK(ifp);
  864                 lle = lla_lookup(LLTABLE(ifp), (LLE_CREATE | LLE_IFADDR | LLE_STATIC),
  865                                  (struct sockaddr *)IA_SIN(ifa));
  866                 IF_AFDATA_UNLOCK(ifp);
  867                 if (lle == NULL)
  868                         log(LOG_INFO, "arp_ifinit: cannot create arp "
  869                             "entry for interface address\n");
  870                 else
  871                         LLE_RUNLOCK(lle);
  872         }
  873         ifa->ifa_rtrequest = NULL;
  874 }
  875 
  876 void
  877 arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
  878 {
  879         if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
  880                 arprequest(ifp, &IA_SIN(ifa)->sin_addr,
  881                                 &IA_SIN(ifa)->sin_addr, enaddr);
  882         ifa->ifa_rtrequest = NULL;
  883 }
  884 
  885 static void
  886 arp_init(void)
  887 {
  888 
  889         netisr_register(&arp_nh);
  890 }
  891 SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);

Cache object: 700b32a748045c83485ca507af768b43


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