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

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    1 /*-
    2  * Copyright (c) 1982, 1989, 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_ethersubr.c      8.1 (Berkeley) 6/10/93
   30  * $FreeBSD: releng/6.3/sys/net/if_ethersubr.c 173886 2007-11-24 19:45:58Z cvs2svn $
   31  */
   32 
   33 #include "opt_atalk.h"
   34 #include "opt_inet.h"
   35 #include "opt_inet6.h"
   36 #include "opt_ipx.h"
   37 #include "opt_bdg.h"
   38 #include "opt_mac.h"
   39 #include "opt_netgraph.h"
   40 #include "opt_carp.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/kernel.h>
   45 #include <sys/mac.h>
   46 #include <sys/malloc.h>
   47 #include <sys/module.h>
   48 #include <sys/mbuf.h>
   49 #include <sys/random.h>
   50 #include <sys/socket.h>
   51 #include <sys/sockio.h>
   52 #include <sys/sysctl.h>
   53 
   54 #include <net/if.h>
   55 #include <net/if_arp.h>
   56 #include <net/netisr.h>
   57 #include <net/route.h>
   58 #include <net/if_llc.h>
   59 #include <net/if_dl.h>
   60 #include <net/if_types.h>
   61 #include <net/bpf.h>
   62 #include <net/ethernet.h>
   63 #include <net/bridge.h>
   64 #include <net/if_bridgevar.h>
   65 #include <net/if_vlan_var.h>
   66 
   67 #if defined(INET) || defined(INET6)
   68 #include <netinet/in.h>
   69 #include <netinet/in_var.h>
   70 #include <netinet/if_ether.h>
   71 #include <netinet/ip_fw.h>
   72 #include <netinet/ip_dummynet.h>
   73 #endif
   74 #ifdef INET6
   75 #include <netinet6/nd6.h>
   76 #endif
   77 
   78 #ifdef DEV_CARP
   79 #include <netinet/ip_carp.h>
   80 #endif
   81 
   82 #ifdef IPX
   83 #include <netipx/ipx.h>
   84 #include <netipx/ipx_if.h>
   85 #endif
   86 int (*ef_inputp)(struct ifnet*, struct ether_header *eh, struct mbuf *m);
   87 int (*ef_outputp)(struct ifnet *ifp, struct mbuf **mp,
   88                 struct sockaddr *dst, short *tp, int *hlen);
   89 
   90 #ifdef NETATALK
   91 #include <netatalk/at.h>
   92 #include <netatalk/at_var.h>
   93 #include <netatalk/at_extern.h>
   94 
   95 #define llc_snap_org_code llc_un.type_snap.org_code
   96 #define llc_snap_ether_type llc_un.type_snap.ether_type
   97 
   98 extern u_char   at_org_code[3];
   99 extern u_char   aarp_org_code[3];
  100 #endif /* NETATALK */
  101 
  102 /* netgraph node hooks for ng_ether(4) */
  103 void    (*ng_ether_input_p)(struct ifnet *ifp, struct mbuf **mp);
  104 void    (*ng_ether_input_orphan_p)(struct ifnet *ifp, struct mbuf *m);
  105 int     (*ng_ether_output_p)(struct ifnet *ifp, struct mbuf **mp);
  106 void    (*ng_ether_attach_p)(struct ifnet *ifp);
  107 void    (*ng_ether_detach_p)(struct ifnet *ifp);
  108 
  109 void    (*vlan_input_p)(struct ifnet *, struct mbuf *);
  110 
  111 /* bridge support */
  112 int do_bridge;
  113 bridge_in_t *bridge_in_ptr;
  114 bdg_forward_t *bdg_forward_ptr;
  115 bdgtakeifaces_t *bdgtakeifaces_ptr;
  116 struct bdg_softc *ifp2sc;
  117 
  118 struct mbuf *(*bridge_input_p)(struct ifnet *, struct mbuf *); 
  119 int     (*bridge_output_p)(struct ifnet *, struct mbuf *, 
  120                 struct sockaddr *, struct rtentry *);
  121 void    (*bridge_dn_p)(struct mbuf *, struct ifnet *);
  122 
  123 /* if_lagg(4) support */
  124 struct mbuf *(*lagg_input_p)(struct ifnet *, struct mbuf *); 
  125 
  126 static const u_char etherbroadcastaddr[ETHER_ADDR_LEN] =
  127                         { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  128 
  129 static  int ether_resolvemulti(struct ifnet *, struct sockaddr **,
  130                 struct sockaddr *);
  131 
  132 /* XXX: should be in an arp support file, not here */
  133 MALLOC_DEFINE(M_ARPCOM, "arpcom", "802.* interface internals");
  134 
  135 #define senderr(e) do { error = (e); goto bad;} while (0)
  136 
  137 #if defined(INET) || defined(INET6)
  138 int
  139 ether_ipfw_chk(struct mbuf **m0, struct ifnet *dst,
  140         struct ip_fw **rule, int shared);
  141 static int ether_ipfw;
  142 #endif
  143 
  144 /*
  145  * Ethernet output routine.
  146  * Encapsulate a packet of type family for the local net.
  147  * Use trailer local net encapsulation if enough data in first
  148  * packet leaves a multiple of 512 bytes of data in remainder.
  149  */
  150 int
  151 ether_output(struct ifnet *ifp, struct mbuf *m,
  152         struct sockaddr *dst, struct rtentry *rt0)
  153 {
  154         short type;
  155         int error, hdrcmplt = 0;
  156         u_char esrc[ETHER_ADDR_LEN], edst[ETHER_ADDR_LEN];
  157         struct ether_header *eh;
  158         int loop_copy = 1;
  159         int hlen;       /* link layer header length */
  160 
  161 #ifdef MAC
  162         error = mac_check_ifnet_transmit(ifp, m);
  163         if (error)
  164                 senderr(error);
  165 #endif
  166 
  167         if (ifp->if_flags & IFF_MONITOR)
  168                 senderr(ENETDOWN);
  169         if (!((ifp->if_flags & IFF_UP) &&
  170             (ifp->if_drv_flags & IFF_DRV_RUNNING)))
  171                 senderr(ENETDOWN);
  172 
  173         hlen = ETHER_HDR_LEN;
  174         switch (dst->sa_family) {
  175 #ifdef INET
  176         case AF_INET:
  177                 error = arpresolve(ifp, rt0, m, dst, edst);
  178                 if (error)
  179                         return (error == EWOULDBLOCK ? 0 : error);
  180                 type = htons(ETHERTYPE_IP);
  181                 break;
  182         case AF_ARP:
  183         {
  184                 struct arphdr *ah;
  185                 ah = mtod(m, struct arphdr *);
  186                 ah->ar_hrd = htons(ARPHRD_ETHER);
  187 
  188                 loop_copy = 0; /* if this is for us, don't do it */
  189 
  190                 switch(ntohs(ah->ar_op)) {
  191                 case ARPOP_REVREQUEST:
  192                 case ARPOP_REVREPLY:
  193                         type = htons(ETHERTYPE_REVARP);
  194                         break;
  195                 case ARPOP_REQUEST:
  196                 case ARPOP_REPLY:
  197                 default:
  198                         type = htons(ETHERTYPE_ARP);
  199                         break;
  200                 }
  201 
  202                 if (m->m_flags & M_BCAST)
  203                         bcopy(ifp->if_broadcastaddr, edst, ETHER_ADDR_LEN);
  204                 else
  205                         bcopy(ar_tha(ah), edst, ETHER_ADDR_LEN);
  206 
  207         }
  208         break;
  209 #endif
  210 #ifdef INET6
  211         case AF_INET6:
  212                 error = nd6_storelladdr(ifp, rt0, m, dst, (u_char *)edst);
  213                 if (error)
  214                         return error;
  215                 type = htons(ETHERTYPE_IPV6);
  216                 break;
  217 #endif
  218 #ifdef IPX
  219         case AF_IPX:
  220                 if (ef_outputp) {
  221                     error = ef_outputp(ifp, &m, dst, &type, &hlen);
  222                     if (error)
  223                         goto bad;
  224                 } else
  225                     type = htons(ETHERTYPE_IPX);
  226                 bcopy((caddr_t)&(((struct sockaddr_ipx *)dst)->sipx_addr.x_host),
  227                     (caddr_t)edst, sizeof (edst));
  228                 break;
  229 #endif
  230 #ifdef NETATALK
  231         case AF_APPLETALK:
  232           {
  233             struct at_ifaddr *aa;
  234 
  235             if ((aa = at_ifawithnet((struct sockaddr_at *)dst)) == NULL)
  236                     senderr(EHOSTUNREACH); /* XXX */
  237             if (!aarpresolve(ifp, m, (struct sockaddr_at *)dst, edst))
  238                     return (0);
  239             /*
  240              * In the phase 2 case, need to prepend an mbuf for the llc header.
  241              */
  242             if ( aa->aa_flags & AFA_PHASE2 ) {
  243                 struct llc llc;
  244 
  245                 M_PREPEND(m, LLC_SNAPFRAMELEN, M_DONTWAIT);
  246                 if (m == NULL)
  247                         senderr(ENOBUFS);
  248                 llc.llc_dsap = llc.llc_ssap = LLC_SNAP_LSAP;
  249                 llc.llc_control = LLC_UI;
  250                 bcopy(at_org_code, llc.llc_snap_org_code, sizeof(at_org_code));
  251                 llc.llc_snap_ether_type = htons( ETHERTYPE_AT );
  252                 bcopy(&llc, mtod(m, caddr_t), LLC_SNAPFRAMELEN);
  253                 type = htons(m->m_pkthdr.len);
  254                 hlen = LLC_SNAPFRAMELEN + ETHER_HDR_LEN;
  255             } else {
  256                 type = htons(ETHERTYPE_AT);
  257             }
  258             break;
  259           }
  260 #endif /* NETATALK */
  261 
  262         case pseudo_AF_HDRCMPLT:
  263                 hdrcmplt = 1;
  264                 eh = (struct ether_header *)dst->sa_data;
  265                 (void)memcpy(esrc, eh->ether_shost, sizeof (esrc));
  266                 /* FALLTHROUGH */
  267 
  268         case AF_UNSPEC:
  269                 loop_copy = 0; /* if this is for us, don't do it */
  270                 eh = (struct ether_header *)dst->sa_data;
  271                 (void)memcpy(edst, eh->ether_dhost, sizeof (edst));
  272                 type = eh->ether_type;
  273                 break;
  274 
  275         default:
  276                 if_printf(ifp, "can't handle af%d\n", dst->sa_family);
  277                 senderr(EAFNOSUPPORT);
  278         }
  279 
  280         /*
  281          * Add local net header.  If no space in first mbuf,
  282          * allocate another.
  283          */
  284         M_PREPEND(m, ETHER_HDR_LEN, M_DONTWAIT);
  285         if (m == NULL)
  286                 senderr(ENOBUFS);
  287         eh = mtod(m, struct ether_header *);
  288         (void)memcpy(&eh->ether_type, &type,
  289                 sizeof(eh->ether_type));
  290         (void)memcpy(eh->ether_dhost, edst, sizeof (edst));
  291         if (hdrcmplt)
  292                 (void)memcpy(eh->ether_shost, esrc,
  293                         sizeof(eh->ether_shost));
  294         else
  295                 (void)memcpy(eh->ether_shost, IFP2ENADDR(ifp),
  296                         sizeof(eh->ether_shost));
  297 
  298         /*
  299          * If a simplex interface, and the packet is being sent to our
  300          * Ethernet address or a broadcast address, loopback a copy.
  301          * XXX To make a simplex device behave exactly like a duplex
  302          * device, we should copy in the case of sending to our own
  303          * ethernet address (thus letting the original actually appear
  304          * on the wire). However, we don't do that here for security
  305          * reasons and compatibility with the original behavior.
  306          */
  307         if ((ifp->if_flags & IFF_SIMPLEX) && loop_copy &&
  308             m_tag_find(m, PACKET_TAG_PF_ROUTED, NULL) == NULL) {
  309                 int csum_flags = 0;
  310 
  311                 if (m->m_pkthdr.csum_flags & CSUM_IP)
  312                         csum_flags |= (CSUM_IP_CHECKED|CSUM_IP_VALID);
  313                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
  314                         csum_flags |= (CSUM_DATA_VALID|CSUM_PSEUDO_HDR);
  315 
  316                 if (m->m_flags & M_BCAST) {
  317                         struct mbuf *n;
  318 
  319                         if ((n = m_copy(m, 0, (int)M_COPYALL)) != NULL) {
  320                                 n->m_pkthdr.csum_flags |= csum_flags;
  321                                 if (csum_flags & CSUM_DATA_VALID)
  322                                         n->m_pkthdr.csum_data = 0xffff;
  323                                 (void)if_simloop(ifp, n, dst->sa_family, hlen);
  324                         } else
  325                                 ifp->if_iqdrops++;
  326                 } else if (bcmp(eh->ether_dhost, eh->ether_shost,
  327                                 ETHER_ADDR_LEN) == 0) {
  328                         m->m_pkthdr.csum_flags |= csum_flags;
  329                         if (csum_flags & CSUM_DATA_VALID)
  330                                 m->m_pkthdr.csum_data = 0xffff;
  331                         (void) if_simloop(ifp, m, dst->sa_family, hlen);
  332                         return (0);     /* XXX */
  333                 }
  334         }
  335 
  336        /*
  337         * Bridges require special output handling.
  338         */
  339         if (ifp->if_bridge) {
  340                 BRIDGE_OUTPUT(ifp, m, error);
  341                 return (error);
  342         }
  343 
  344 #ifdef DEV_CARP
  345         if (ifp->if_carp &&
  346             (error = carp_output(ifp, m, dst, NULL)))
  347                 goto bad;
  348 #endif
  349 
  350         /* Handle ng_ether(4) processing, if any */
  351         if (IFP2AC(ifp)->ac_netgraph != NULL) {
  352                 if ((error = (*ng_ether_output_p)(ifp, &m)) != 0) {
  353 bad:                    if (m != NULL)
  354                                 m_freem(m);
  355                         return (error);
  356                 }
  357                 if (m == NULL)
  358                         return (0);
  359         }
  360 
  361         /* Continue with link-layer output */
  362         return ether_output_frame(ifp, m);
  363 }
  364 
  365 /*
  366  * Ethernet link layer output routine to send a raw frame to the device.
  367  *
  368  * This assumes that the 14 byte Ethernet header is present and contiguous
  369  * in the first mbuf (if BRIDGE'ing).
  370  */
  371 int
  372 ether_output_frame(struct ifnet *ifp, struct mbuf *m)
  373 {
  374 #if defined(INET) || defined(INET6)
  375         struct ip_fw *rule = ip_dn_claim_rule(m);
  376 #else
  377         void *rule = NULL;
  378 #endif
  379         int error;
  380 
  381         if (rule == NULL && BDG_ACTIVE(ifp)) {
  382                 /*
  383                  * Beware, the bridge code notices the null rcvif and
  384                  * uses that identify that it's being called from
  385                  * ether_output as opposd to ether_input.  Yech.
  386                  */
  387                 m->m_pkthdr.rcvif = NULL;
  388                 m = bdg_forward_ptr(m, ifp);
  389                 if (m != NULL)
  390                         m_freem(m);
  391                 return (0);
  392         }
  393 #if defined(INET) || defined(INET6)
  394         if (IPFW_LOADED && ether_ipfw != 0) {
  395                 if (ether_ipfw_chk(&m, ifp, &rule, 0) == 0) {
  396                         if (m) {
  397                                 m_freem(m);
  398                                 return EACCES;  /* pkt dropped */
  399                         } else
  400                                 return 0;       /* consumed e.g. in a pipe */
  401                 }
  402         }
  403 #endif
  404 
  405         /*
  406          * Queue message on interface, update output statistics if
  407          * successful, and start output if interface not yet active.
  408          */
  409         IFQ_HANDOFF(ifp, m, error);
  410         return (error);
  411 }
  412 
  413 #if defined(INET) || defined(INET6)
  414 /*
  415  * ipfw processing for ethernet packets (in and out).
  416  * The second parameter is NULL from ether_demux, and ifp from
  417  * ether_output_frame. This section of code could be used from
  418  * bridge.c as well as long as we use some extra info
  419  * to distinguish that case from ether_output_frame();
  420  */
  421 int
  422 ether_ipfw_chk(struct mbuf **m0, struct ifnet *dst,
  423         struct ip_fw **rule, int shared)
  424 {
  425         struct ether_header *eh;
  426         struct ether_header save_eh;
  427         struct mbuf *m;
  428         int i;
  429         struct ip_fw_args args;
  430 
  431         if (*rule != NULL && fw_one_pass)
  432                 return 1; /* dummynet packet, already partially processed */
  433 
  434         /*
  435          * I need some amt of data to be contiguous, and in case others need
  436          * the packet (shared==1) also better be in the first mbuf.
  437          */
  438         m = *m0;
  439         i = min( m->m_pkthdr.len, max_protohdr);
  440         if ( shared || m->m_len < i) {
  441                 m = m_pullup(m, i);
  442                 if (m == NULL) {
  443                         *m0 = m;
  444                         return 0;
  445                 }
  446         }
  447         eh = mtod(m, struct ether_header *);
  448         save_eh = *eh;                  /* save copy for restore below */
  449         m_adj(m, ETHER_HDR_LEN);        /* strip ethernet header */
  450 
  451         args.m = m;             /* the packet we are looking at         */
  452         args.oif = dst;         /* destination, if any                  */
  453         args.rule = *rule;      /* matching rule to restart             */
  454         args.next_hop = NULL;   /* we do not support forward yet        */
  455         args.eh = &save_eh;     /* MAC header for bridged/MAC packets   */
  456         args.inp = NULL;        /* used by ipfw uid/gid/jail rules      */
  457         i = ip_fw_chk_ptr(&args);
  458         m = args.m;
  459         if (m != NULL) {
  460                 /*
  461                  * Restore Ethernet header, as needed, in case the
  462                  * mbuf chain was replaced by ipfw.
  463                  */
  464                 M_PREPEND(m, ETHER_HDR_LEN, M_DONTWAIT);
  465                 if (m == NULL) {
  466                         *m0 = m;
  467                         return 0;
  468                 }
  469                 if (eh != mtod(m, struct ether_header *))
  470                         bcopy(&save_eh, mtod(m, struct ether_header *),
  471                                 ETHER_HDR_LEN);
  472         }
  473         *m0 = m;
  474         *rule = args.rule;
  475 
  476         if (i == IP_FW_DENY) /* drop */
  477                 return 0;
  478 
  479         KASSERT(m != NULL, ("ether_ipfw_chk: m is NULL"));
  480 
  481         if (i == IP_FW_PASS) /* a PASS rule.  */
  482                 return 1;
  483 
  484         if (DUMMYNET_LOADED && (i == IP_FW_DUMMYNET)) {
  485                 /*
  486                  * Pass the pkt to dummynet, which consumes it.
  487                  * If shared, make a copy and keep the original.
  488                  */
  489                 if (shared) {
  490                         m = m_copypacket(m, M_DONTWAIT);
  491                         if (m == NULL)
  492                                 return 0;
  493                 } else {
  494                         /*
  495                          * Pass the original to dummynet and
  496                          * nothing back to the caller
  497                          */
  498                         *m0 = NULL ;
  499                 }
  500                 ip_dn_io_ptr(m, dst ? DN_TO_ETH_OUT: DN_TO_ETH_DEMUX, &args);
  501                 return 0;
  502         }
  503         /*
  504          * XXX at some point add support for divert/forward actions.
  505          * If none of the above matches, we have to drop the pkt.
  506          */
  507         return 0;
  508 }
  509 #endif
  510 
  511 /*
  512  * Process a received Ethernet packet; the packet is in the
  513  * mbuf chain m with the ethernet header at the front.
  514  */
  515 static void
  516 ether_input(struct ifnet *ifp, struct mbuf *m)
  517 {
  518         struct ether_header *eh;
  519         u_short etype;
  520 
  521         /*
  522          * Do consistency checks to verify assumptions
  523          * made by code past this point.
  524          */
  525         if ((m->m_flags & M_PKTHDR) == 0) {
  526                 if_printf(ifp, "discard frame w/o packet header\n");
  527                 ifp->if_ierrors++;
  528                 m_freem(m);
  529                 return;
  530         }
  531         if (m->m_len < ETHER_HDR_LEN) {
  532                 /* XXX maybe should pullup? */
  533                 if_printf(ifp, "discard frame w/o leading ethernet "
  534                                 "header (len %u pkt len %u)\n",
  535                                 m->m_len, m->m_pkthdr.len);
  536                 ifp->if_ierrors++;
  537                 m_freem(m);
  538                 return;
  539         }
  540         eh = mtod(m, struct ether_header *);
  541         etype = ntohs(eh->ether_type);
  542         if (m->m_pkthdr.rcvif == NULL) {
  543                 if_printf(ifp, "discard frame w/o interface pointer\n");
  544                 ifp->if_ierrors++;
  545                 m_freem(m);
  546                 return;
  547         }
  548 #ifdef DIAGNOSTIC
  549         if (m->m_pkthdr.rcvif != ifp) {
  550                 if_printf(ifp, "Warning, frame marked as received on %s\n",
  551                         m->m_pkthdr.rcvif->if_xname);
  552         }
  553 #endif
  554 
  555 #ifdef MAC
  556         /*
  557          * Tag the mbuf with an appropriate MAC label before any other
  558          * consumers can get to it.
  559          */
  560         mac_create_mbuf_from_ifnet(ifp, m);
  561 #endif
  562 
  563         /*
  564          * Give bpf a chance at the packet.
  565          */
  566         ETHER_BPF_MTAP(ifp, m);
  567 
  568         /* If the CRC is still on the packet, trim it off. */
  569         if (m->m_flags & M_HASFCS) {
  570                 m_adj(m, -ETHER_CRC_LEN);
  571                 m->m_flags &= ~M_HASFCS;
  572         }
  573 
  574         ifp->if_ibytes += m->m_pkthdr.len;
  575 
  576         if (ifp->if_flags & IFF_MONITOR) {
  577                 /*
  578                  * Interface marked for monitoring; discard packet.
  579                  */
  580                 m_freem(m);
  581                 return;
  582         }
  583 
  584         /* Handle input from a lagg(4) port */
  585         if (ifp->if_type == IFT_IEEE8023ADLAG) {
  586                 KASSERT(lagg_input_p != NULL,
  587                     ("%s: if_lagg not loaded!", __func__));
  588                 m = (*lagg_input_p)(ifp, m);
  589                 if (m != NULL)
  590                         ifp = m->m_pkthdr.rcvif;
  591                 else
  592                         return;
  593         }
  594 
  595         /* Handle ng_ether(4) processing, if any */
  596         if (IFP2AC(ifp)->ac_netgraph != NULL) {
  597                 (*ng_ether_input_p)(ifp, &m);
  598                 if (m == NULL)
  599                         return;
  600         }
  601 
  602         /*
  603          * Tap the packet off here for a bridge.  bridge_input()
  604          * will return NULL if it has consumed the packet, otherwise
  605          * it gets processed as normal.  Note that bridge_input()
  606          * will always return the original packet if we need to
  607          * process it locally.
  608          */
  609         if (ifp->if_bridge) {
  610                 BRIDGE_INPUT(ifp, m);
  611                 if (m == NULL)
  612                         return;
  613         }
  614 
  615         /* Check for bridging mode */
  616         if (BDG_ACTIVE(ifp) )
  617                 if ((m = bridge_in_ptr(ifp, m)) == NULL)
  618                         return;
  619 
  620         /* First chunk of an mbuf contains good entropy */
  621         if (harvest.ethernet)
  622                 random_harvest(m, 16, 3, 0, RANDOM_NET);
  623         ether_demux(ifp, m);
  624 }
  625 
  626 /*
  627  * Upper layer processing for a received Ethernet packet.
  628  */
  629 void
  630 ether_demux(struct ifnet *ifp, struct mbuf *m)
  631 {
  632         struct ether_header *eh;
  633         int isr;
  634         u_short ether_type;
  635 #if defined(NETATALK)
  636         struct llc *l;
  637 #endif
  638 #if defined(INET) || defined(INET6)
  639         struct ip_fw *rule = ip_dn_claim_rule(m);
  640 #endif
  641 
  642         KASSERT(ifp != NULL, ("ether_demux: NULL interface pointer"));
  643 
  644         eh = mtod(m, struct ether_header *);
  645         ether_type = ntohs(eh->ether_type);
  646 
  647 #if defined(INET) || defined(INET6)
  648         if (rule)       /* packet was already bridged */
  649                 goto post_stats;
  650 #endif
  651 
  652         if (!(BDG_ACTIVE(ifp)) && !(ifp->if_bridge) &&
  653             !((ether_type == ETHERTYPE_VLAN || m->m_flags & M_VLANTAG) &&
  654             ifp->if_nvlans > 0)) {
  655 #ifdef DEV_CARP
  656                 /*
  657                  * XXX: Okay, we need to call carp_forus() and - if it is for
  658                  * us jump over code that does the normal check
  659                  * "IFP2ENADDR(ifp) == ether_dhost". The check sequence is a bit
  660                  * different from OpenBSD, so we jump over as few code as
  661                  * possible, to catch _all_ sanity checks. This needs
  662                  * evaluation, to see if the carp ether_dhost values break any
  663                  * of these checks!
  664                  */
  665                 if (ifp->if_carp && carp_forus(ifp->if_carp, eh->ether_dhost))
  666                         goto pre_stats;
  667 #endif
  668                 /*
  669                  * Discard packet if upper layers shouldn't see it because it
  670                  * was unicast to a different Ethernet address. If the driver
  671                  * is working properly, then this situation can only happen
  672                  * when the interface is in promiscuous mode.
  673                  *
  674                  * If VLANs are active, and this packet has a VLAN tag, do
  675                  * not drop it here but pass it on to the VLAN layer, to
  676                  * give them a chance to consider it as well (e. g. in case
  677                  * bridging is only active on a VLAN).  They will drop it if
  678                  * it's undesired.
  679                  */
  680                 if ((ifp->if_flags & IFF_PROMISC) != 0
  681                     && !ETHER_IS_MULTICAST(eh->ether_dhost)
  682                     && bcmp(eh->ether_dhost,
  683                       IFP2ENADDR(ifp), ETHER_ADDR_LEN) != 0
  684                     && (ifp->if_flags & IFF_PPROMISC) == 0) {
  685                             m_freem(m);
  686                             return;
  687                 }
  688         }
  689 
  690 #ifdef DEV_CARP
  691 pre_stats:
  692 #endif
  693         /* Discard packet if interface is not up */
  694         if ((ifp->if_flags & IFF_UP) == 0) {
  695                 m_freem(m);
  696                 return;
  697         }
  698         if (ETHER_IS_MULTICAST(eh->ether_dhost)) {
  699                 if (bcmp(etherbroadcastaddr, eh->ether_dhost,
  700                     sizeof(etherbroadcastaddr)) == 0)
  701                         m->m_flags |= M_BCAST;
  702                 else
  703                         m->m_flags |= M_MCAST;
  704         }
  705         if (m->m_flags & (M_BCAST|M_MCAST))
  706                 ifp->if_imcasts++;
  707 
  708 #if defined(INET) || defined(INET6)
  709 post_stats:
  710         if (IPFW_LOADED && ether_ipfw != 0) {
  711                 if (ether_ipfw_chk(&m, NULL, &rule, 0) == 0) {
  712                         if (m)
  713                                 m_freem(m);
  714                         return;
  715                 }
  716         }
  717 #endif
  718 
  719         /*
  720          * Check to see if the device performed the VLAN decapsulation and
  721          * provided us with the tag.
  722          */
  723         if (m->m_flags & M_VLANTAG) {
  724                 /*
  725                  * If no VLANs are configured, drop.
  726                  */
  727                 if (ifp->if_nvlans == 0) {
  728                         ifp->if_noproto++;
  729                         m_freem(m);
  730                         return;
  731                 }
  732                 /*
  733                  * vlan_input() will either recursively call ether_input()
  734                  * or drop the packet.
  735                  */
  736                 KASSERT(vlan_input_p != NULL,("ether_input: VLAN not loaded!"));
  737                 (*vlan_input_p)(ifp, m);
  738                 return;
  739         }
  740 
  741         /*
  742          * Handle protocols that expect to have the Ethernet header
  743          * (and possibly FCS) intact.
  744          */
  745         switch (ether_type) {
  746         case ETHERTYPE_VLAN:
  747                 if (ifp->if_nvlans != 0) {
  748                         KASSERT(vlan_input_p,("ether_input: VLAN not loaded!"));
  749                         (*vlan_input_p)(ifp, m);
  750                 } else {
  751                         ifp->if_noproto++;
  752                         m_freem(m);
  753                 }
  754                 return;
  755         }
  756 
  757         /* Strip off Ethernet header. */
  758         m_adj(m, ETHER_HDR_LEN);
  759 
  760         /* If the CRC is still on the packet, trim it off. */
  761         if (m->m_flags & M_HASFCS) {
  762                 m_adj(m, -ETHER_CRC_LEN);
  763                 m->m_flags &= ~M_HASFCS;
  764         }
  765 
  766         switch (ether_type) {
  767 #ifdef INET
  768         case ETHERTYPE_IP:
  769                 if (ip_fastforward(m))
  770                         return;
  771                 isr = NETISR_IP;
  772                 break;
  773 
  774         case ETHERTYPE_ARP:
  775                 if (ifp->if_flags & IFF_NOARP) {
  776                         /* Discard packet if ARP is disabled on interface */
  777                         m_freem(m);
  778                         return;
  779                 }
  780                 isr = NETISR_ARP;
  781                 break;
  782 #endif
  783 #ifdef IPX
  784         case ETHERTYPE_IPX:
  785                 if (ef_inputp && ef_inputp(ifp, eh, m) == 0)
  786                         return;
  787                 isr = NETISR_IPX;
  788                 break;
  789 #endif
  790 #ifdef INET6
  791         case ETHERTYPE_IPV6:
  792                 isr = NETISR_IPV6;
  793                 break;
  794 #endif
  795 #ifdef NETATALK
  796         case ETHERTYPE_AT:
  797                 isr = NETISR_ATALK1;
  798                 break;
  799         case ETHERTYPE_AARP:
  800                 isr = NETISR_AARP;
  801                 break;
  802 #endif /* NETATALK */
  803         default:
  804 #ifdef IPX
  805                 if (ef_inputp && ef_inputp(ifp, eh, m) == 0)
  806                         return;
  807 #endif /* IPX */
  808 #if defined(NETATALK)
  809                 if (ether_type > ETHERMTU)
  810                         goto discard;
  811                 l = mtod(m, struct llc *);
  812                 if (l->llc_dsap == LLC_SNAP_LSAP &&
  813                     l->llc_ssap == LLC_SNAP_LSAP &&
  814                     l->llc_control == LLC_UI) {
  815                         if (bcmp(&(l->llc_snap_org_code)[0], at_org_code,
  816                             sizeof(at_org_code)) == 0 &&
  817                             ntohs(l->llc_snap_ether_type) == ETHERTYPE_AT) {
  818                                 m_adj(m, LLC_SNAPFRAMELEN);
  819                                 isr = NETISR_ATALK2;
  820                                 break;
  821                         }
  822                         if (bcmp(&(l->llc_snap_org_code)[0], aarp_org_code,
  823                             sizeof(aarp_org_code)) == 0 &&
  824                             ntohs(l->llc_snap_ether_type) == ETHERTYPE_AARP) {
  825                                 m_adj(m, LLC_SNAPFRAMELEN);
  826                                 isr = NETISR_AARP;
  827                                 break;
  828                         }
  829                 }
  830 #endif /* NETATALK */
  831                 goto discard;
  832         }
  833         netisr_dispatch(isr, m);
  834         return;
  835 
  836 discard:
  837         /*
  838          * Packet is to be discarded.  If netgraph is present,
  839          * hand the packet to it for last chance processing;
  840          * otherwise dispose of it.
  841          */
  842         if (IFP2AC(ifp)->ac_netgraph != NULL) {
  843                 /*
  844                  * Put back the ethernet header so netgraph has a
  845                  * consistent view of inbound packets.
  846                  */
  847                 M_PREPEND(m, ETHER_HDR_LEN, M_DONTWAIT);
  848                 (*ng_ether_input_orphan_p)(ifp, m);
  849                 return;
  850         }
  851         m_freem(m);
  852 }
  853 
  854 /*
  855  * Convert Ethernet address to printable (loggable) representation.
  856  * This routine is for compatibility; it's better to just use
  857  *
  858  *      printf("%6D", <pointer to address>, ":");
  859  *
  860  * since there's no static buffer involved.
  861  */
  862 char *
  863 ether_sprintf(const u_char *ap)
  864 {
  865         static char etherbuf[18];
  866         snprintf(etherbuf, sizeof (etherbuf), "%6D", ap, ":");
  867         return (etherbuf);
  868 }
  869 
  870 /*
  871  * Perform common duties while attaching to interface list
  872  */
  873 void
  874 ether_ifattach(struct ifnet *ifp, const u_int8_t *llc)
  875 {
  876         int i;
  877         struct ifaddr *ifa;
  878         struct sockaddr_dl *sdl;
  879 
  880         ifp->if_addrlen = ETHER_ADDR_LEN;
  881         ifp->if_hdrlen = ETHER_HDR_LEN;
  882         if_attach(ifp);
  883         ifp->if_mtu = ETHERMTU;
  884         ifp->if_output = ether_output;
  885         ifp->if_input = ether_input;
  886         ifp->if_resolvemulti = ether_resolvemulti;
  887         if (ifp->if_baudrate == 0)
  888                 ifp->if_baudrate = IF_Mbps(10);         /* just a default */
  889         ifp->if_broadcastaddr = etherbroadcastaddr;
  890 
  891         ifa = ifaddr_byindex(ifp->if_index);
  892         KASSERT(ifa != NULL, ("%s: no lladdr!\n", __func__));
  893         sdl = (struct sockaddr_dl *)ifa->ifa_addr;
  894         sdl->sdl_type = IFT_ETHER;
  895         sdl->sdl_alen = ifp->if_addrlen;
  896         bcopy(llc, LLADDR(sdl), ifp->if_addrlen);
  897         /*
  898          * XXX: This doesn't belong here; we do it until
  899          * XXX:  all drivers are cleaned up
  900          */
  901         if (llc != IFP2ENADDR(ifp))
  902                 bcopy(llc, IFP2ENADDR(ifp), ifp->if_addrlen);
  903 
  904         bpfattach(ifp, DLT_EN10MB, ETHER_HDR_LEN);
  905         if (ng_ether_attach_p != NULL)
  906                 (*ng_ether_attach_p)(ifp);
  907         if (BDG_LOADED)
  908                 bdgtakeifaces_ptr();
  909 
  910         /* Announce Ethernet MAC address if non-zero. */
  911         for (i = 0; i < ifp->if_addrlen; i++)
  912                 if (llc[i] != 0)
  913                         break; 
  914         if (i != ifp->if_addrlen)
  915                 if_printf(ifp, "Ethernet address: %6D\n", llc, ":");
  916         if (debug_mpsafenet && (ifp->if_flags & IFF_NEEDSGIANT) != 0)
  917                 if_printf(ifp, "if_start running deferred for Giant\n");
  918 }
  919 
  920 /*
  921  * Perform common duties while detaching an Ethernet interface
  922  */
  923 void
  924 ether_ifdetach(struct ifnet *ifp)
  925 {
  926         if (IFP2AC(ifp)->ac_netgraph != NULL)
  927                 (*ng_ether_detach_p)(ifp);
  928 
  929         bpfdetach(ifp);
  930         if_detach(ifp);
  931         if (BDG_LOADED)
  932                 bdgtakeifaces_ptr();
  933 }
  934 
  935 SYSCTL_DECL(_net_link);
  936 SYSCTL_NODE(_net_link, IFT_ETHER, ether, CTLFLAG_RW, 0, "Ethernet");
  937 #if defined(INET) || defined(INET6)
  938 SYSCTL_INT(_net_link_ether, OID_AUTO, ipfw, CTLFLAG_RW,
  939             &ether_ipfw,0,"Pass ether pkts through firewall");
  940 #endif
  941 
  942 #if 0
  943 /*
  944  * This is for reference.  We have a table-driven version
  945  * of the little-endian crc32 generator, which is faster
  946  * than the double-loop.
  947  */
  948 uint32_t
  949 ether_crc32_le(const uint8_t *buf, size_t len)
  950 {
  951         size_t i;
  952         uint32_t crc;
  953         int bit;
  954         uint8_t data;
  955 
  956         crc = 0xffffffff;       /* initial value */
  957 
  958         for (i = 0; i < len; i++) {
  959                 for (data = *buf++, bit = 0; bit < 8; bit++, data >>= 1)
  960                         carry = (crc ^ data) & 1;
  961                         crc >>= 1;
  962                         if (carry)
  963                                 crc = (crc ^ ETHER_CRC_POLY_LE);
  964         }
  965 
  966         return (crc);
  967 }
  968 #else
  969 uint32_t
  970 ether_crc32_le(const uint8_t *buf, size_t len)
  971 {
  972         static const uint32_t crctab[] = {
  973                 0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
  974                 0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
  975                 0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
  976                 0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
  977         };
  978         size_t i;
  979         uint32_t crc;
  980 
  981         crc = 0xffffffff;       /* initial value */
  982 
  983         for (i = 0; i < len; i++) {
  984                 crc ^= buf[i];
  985                 crc = (crc >> 4) ^ crctab[crc & 0xf];
  986                 crc = (crc >> 4) ^ crctab[crc & 0xf];
  987         }
  988 
  989         return (crc);
  990 }
  991 #endif
  992 
  993 uint32_t
  994 ether_crc32_be(const uint8_t *buf, size_t len)
  995 {
  996         size_t i;
  997         uint32_t crc, carry;
  998         int bit;
  999         uint8_t data;
 1000 
 1001         crc = 0xffffffff;       /* initial value */
 1002 
 1003         for (i = 0; i < len; i++) {
 1004                 for (data = *buf++, bit = 0; bit < 8; bit++, data >>= 1) {
 1005                         carry = ((crc & 0x80000000) ? 1 : 0) ^ (data & 0x01);
 1006                         crc <<= 1;
 1007                         if (carry)
 1008                                 crc = (crc ^ ETHER_CRC_POLY_BE) | carry;
 1009                 }
 1010         }
 1011 
 1012         return (crc);
 1013 }
 1014 
 1015 int
 1016 ether_ioctl(struct ifnet *ifp, int command, caddr_t data)
 1017 {
 1018         struct ifaddr *ifa = (struct ifaddr *) data;
 1019         struct ifreq *ifr = (struct ifreq *) data;
 1020         int error = 0;
 1021 
 1022         switch (command) {
 1023         case SIOCSIFADDR:
 1024                 ifp->if_flags |= IFF_UP;
 1025 
 1026                 switch (ifa->ifa_addr->sa_family) {
 1027 #ifdef INET
 1028                 case AF_INET:
 1029                         ifp->if_init(ifp->if_softc);    /* before arpwhohas */
 1030                         arp_ifinit(ifp, ifa);
 1031                         break;
 1032 #endif
 1033 #ifdef IPX
 1034                 /*
 1035                  * XXX - This code is probably wrong
 1036                  */
 1037                 case AF_IPX:
 1038                         {
 1039                         struct ipx_addr *ina = &(IA_SIPX(ifa)->sipx_addr);
 1040 
 1041                         if (ipx_nullhost(*ina))
 1042                                 ina->x_host =
 1043                                     *(union ipx_host *)
 1044                                     IFP2ENADDR(ifp);
 1045                         else {
 1046                                 bcopy((caddr_t) ina->x_host.c_host,
 1047                                       (caddr_t) IFP2ENADDR(ifp),
 1048                                       ETHER_ADDR_LEN);
 1049                         }
 1050 
 1051                         /*
 1052                          * Set new address
 1053                          */
 1054                         ifp->if_init(ifp->if_softc);
 1055                         break;
 1056                         }
 1057 #endif
 1058                 default:
 1059                         ifp->if_init(ifp->if_softc);
 1060                         break;
 1061                 }
 1062                 break;
 1063 
 1064         case SIOCGIFADDR:
 1065                 {
 1066                         struct sockaddr *sa;
 1067 
 1068                         sa = (struct sockaddr *) & ifr->ifr_data;
 1069                         bcopy(IFP2ENADDR(ifp),
 1070                               (caddr_t) sa->sa_data, ETHER_ADDR_LEN);
 1071                 }
 1072                 break;
 1073 
 1074         case SIOCSIFMTU:
 1075                 /*
 1076                  * Set the interface MTU.
 1077                  */
 1078                 if (ifr->ifr_mtu > ETHERMTU) {
 1079                         error = EINVAL;
 1080                 } else {
 1081                         ifp->if_mtu = ifr->ifr_mtu;
 1082                 }
 1083                 break;
 1084         default:
 1085                 error = EINVAL;                 /* XXX netbsd has ENOTTY??? */
 1086                 break;
 1087         }
 1088         return (error);
 1089 }
 1090 
 1091 static int
 1092 ether_resolvemulti(struct ifnet *ifp, struct sockaddr **llsa,
 1093         struct sockaddr *sa)
 1094 {
 1095         struct sockaddr_dl *sdl;
 1096 #ifdef INET
 1097         struct sockaddr_in *sin;
 1098 #endif
 1099 #ifdef INET6
 1100         struct sockaddr_in6 *sin6;
 1101 #endif
 1102         u_char *e_addr;
 1103 
 1104         switch(sa->sa_family) {
 1105         case AF_LINK:
 1106                 /*
 1107                  * No mapping needed. Just check that it's a valid MC address.
 1108                  */
 1109                 sdl = (struct sockaddr_dl *)sa;
 1110                 e_addr = LLADDR(sdl);
 1111                 if (!ETHER_IS_MULTICAST(e_addr))
 1112                         return EADDRNOTAVAIL;
 1113                 *llsa = 0;
 1114                 return 0;
 1115 
 1116 #ifdef INET
 1117         case AF_INET:
 1118                 sin = (struct sockaddr_in *)sa;
 1119                 if (!IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
 1120                         return EADDRNOTAVAIL;
 1121                 MALLOC(sdl, struct sockaddr_dl *, sizeof *sdl, M_IFMADDR,
 1122                        M_NOWAIT|M_ZERO);
 1123                 if (sdl == NULL)
 1124                         return ENOMEM;
 1125                 sdl->sdl_len = sizeof *sdl;
 1126                 sdl->sdl_family = AF_LINK;
 1127                 sdl->sdl_index = ifp->if_index;
 1128                 sdl->sdl_type = IFT_ETHER;
 1129                 sdl->sdl_alen = ETHER_ADDR_LEN;
 1130                 e_addr = LLADDR(sdl);
 1131                 ETHER_MAP_IP_MULTICAST(&sin->sin_addr, e_addr);
 1132                 *llsa = (struct sockaddr *)sdl;
 1133                 return 0;
 1134 #endif
 1135 #ifdef INET6
 1136         case AF_INET6:
 1137                 sin6 = (struct sockaddr_in6 *)sa;
 1138                 if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) {
 1139                         /*
 1140                          * An IP6 address of 0 means listen to all
 1141                          * of the Ethernet multicast address used for IP6.
 1142                          * (This is used for multicast routers.)
 1143                          */
 1144                         ifp->if_flags |= IFF_ALLMULTI;
 1145                         *llsa = 0;
 1146                         return 0;
 1147                 }
 1148                 if (!IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
 1149                         return EADDRNOTAVAIL;
 1150                 MALLOC(sdl, struct sockaddr_dl *, sizeof *sdl, M_IFMADDR,
 1151                        M_NOWAIT|M_ZERO);
 1152                 if (sdl == NULL)
 1153                         return (ENOMEM);
 1154                 sdl->sdl_len = sizeof *sdl;
 1155                 sdl->sdl_family = AF_LINK;
 1156                 sdl->sdl_index = ifp->if_index;
 1157                 sdl->sdl_type = IFT_ETHER;
 1158                 sdl->sdl_alen = ETHER_ADDR_LEN;
 1159                 e_addr = LLADDR(sdl);
 1160                 ETHER_MAP_IPV6_MULTICAST(&sin6->sin6_addr, e_addr);
 1161                 *llsa = (struct sockaddr *)sdl;
 1162                 return 0;
 1163 #endif
 1164 
 1165         default:
 1166                 /*
 1167                  * Well, the text isn't quite right, but it's the name
 1168                  * that counts...
 1169                  */
 1170                 return EAFNOSUPPORT;
 1171         }
 1172 }
 1173 
 1174 static void*
 1175 ether_alloc(u_char type, struct ifnet *ifp)
 1176 {
 1177         struct arpcom   *ac;
 1178         
 1179         ac = malloc(sizeof(struct arpcom), M_ARPCOM, M_WAITOK | M_ZERO);
 1180         ac->ac_ifp = ifp;
 1181 
 1182         return (ac);
 1183 }
 1184 
 1185 static void
 1186 ether_free(void *com, u_char type)
 1187 {
 1188 
 1189         free(com, M_ARPCOM);
 1190 }
 1191 
 1192 static int
 1193 ether_modevent(module_t mod, int type, void *data)
 1194 {
 1195 
 1196         switch (type) {
 1197         case MOD_LOAD:
 1198                 if_register_com_alloc(IFT_ETHER, ether_alloc, ether_free);
 1199                 break;
 1200         case MOD_UNLOAD:
 1201                 if_deregister_com_alloc(IFT_ETHER);
 1202                 break;
 1203         default:
 1204                 return EOPNOTSUPP;
 1205         }
 1206 
 1207         return (0);
 1208 }
 1209 
 1210 static moduledata_t ether_mod = {
 1211         "ether",
 1212         ether_modevent,
 1213         0
 1214 };
 1215 
 1216 void
 1217 ether_vlan_mtap(struct bpf_if *bp, struct mbuf *m, void *data, u_int dlen)
 1218 {
 1219         struct ether_vlan_header vlan;
 1220         struct mbuf mv, mb;
 1221         struct m_tag *mtag;
 1222         u_int tag;
 1223 
 1224         KASSERT((m->m_flags & M_VLANTAG) != 0,
 1225             ("%s: vlan information not present", __func__));
 1226         KASSERT(m->m_len >= sizeof(struct ether_header),
 1227             ("%s: mbuf not large enough for header", __func__));
 1228         mtag = m_tag_locate(m, MTAG_VLAN, MTAG_VLAN_TAG, NULL);
 1229         KASSERT(mtag != NULL,
 1230             ("%s: NULL mtag with M_VLANTAG", __func__));
 1231         tag = EVL_VLANOFTAG(VLAN_TAG_VALUE(mtag));
 1232         bcopy(mtod(m, char *), &vlan, sizeof(struct ether_header));
 1233         vlan.evl_proto = vlan.evl_encap_proto;
 1234         vlan.evl_encap_proto = htons(ETHERTYPE_VLAN);
 1235         vlan.evl_tag = htons(tag);
 1236         m->m_len -= sizeof(struct ether_header);
 1237         m->m_data += sizeof(struct ether_header);
 1238         /*
 1239          * If a data link has been supplied by the caller, then we will need to
 1240          * re-create a stack allocated mbuf chain with the following structure:
 1241          *
 1242          * (1) mbuf #1 will contain the supplied data link
 1243          * (2) mbuf #2 will contain the vlan header
 1244          * (3) mbuf #3 will contain the original mbuf's packet data
 1245          *
 1246          * Otherwise, submit the packet and vlan header via bpf_mtap2().
 1247          */
 1248         if (data != NULL) {
 1249                 mv.m_next = m;
 1250                 mv.m_data = (caddr_t)&vlan;
 1251                 mv.m_len = sizeof(vlan);
 1252                 mb.m_next = &mv;
 1253                 mb.m_data = data;
 1254                 mb.m_len = dlen;
 1255                 bpf_mtap(bp, &mb);
 1256         } else
 1257                 bpf_mtap2(bp, &vlan, sizeof(vlan), m);
 1258         m->m_len += sizeof(struct ether_header);
 1259         m->m_data -= sizeof(struct ether_header);
 1260 }
 1261 
 1262 DECLARE_MODULE(ether, ether_mod, SI_SUB_INIT_IF, SI_ORDER_ANY);
 1263 MODULE_VERSION(ether, 1);

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