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

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    1 /*
    2  * Copyright (c) 1982, 1986, 1991, 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  * 3. All advertising materials mentioning features or use of this software
   14  *    must display the following acknowledgement:
   15  *      This product includes software developed by the University of
   16  *      California, Berkeley and its contributors.
   17  * 4. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  *      @(#)in.c        8.4 (Berkeley) 1/9/95
   34  * $FreeBSD: src/sys/netinet/in.c,v 1.25.2.2 1999/09/05 08:18:17 peter Exp $
   35  */
   36 
   37 #include <sys/param.h>
   38 #include <sys/queue.h>
   39 #include <sys/systm.h>
   40 #include <sys/ioctl.h>
   41 #include <sys/errno.h>
   42 #include <sys/malloc.h>
   43 #include <sys/socket.h>
   44 #include <sys/socketvar.h>
   45 #include <sys/kernel.h>
   46 #include <sys/sysctl.h>
   47 
   48 #include <net/if.h>
   49 #include <net/route.h>
   50 
   51 #include <netinet/in_systm.h>
   52 #include <netinet/in.h>
   53 #include <netinet/in_var.h>
   54 #include <netinet/if_ether.h>
   55 
   56 #include <netinet/igmp_var.h>
   57 
   58 /*
   59  * This structure is used to keep track of in_multi chains which belong to
   60  * deleted interface addresses.
   61  */
   62 static LIST_HEAD(, multi_kludge) in_mk; /* XXX BSS initialization */
   63 
   64 struct multi_kludge {
   65         LIST_ENTRY(multi_kludge) mk_entry;
   66         struct ifnet *mk_ifp;
   67         struct in_multihead mk_head;
   68 };
   69 
   70 static void     in_socktrim __P((struct sockaddr_in *));
   71 static int      in_ifinit __P((struct ifnet *,
   72             struct in_ifaddr *, struct sockaddr_in *, int));
   73 static void     in_ifscrub __P((struct ifnet *, struct in_ifaddr *));
   74 
   75 static int subnetsarelocal = 0;
   76 SYSCTL_INT(_net_inet_ip, OID_AUTO, subnets_are_local, CTLFLAG_RW, 
   77         &subnetsarelocal, 0, "");
   78 /*
   79  * Return 1 if an internet address is for a ``local'' host
   80  * (one to which we have a connection).  If subnetsarelocal
   81  * is true, this includes other subnets of the local net.
   82  * Otherwise, it includes only the directly-connected (sub)nets.
   83  */
   84 int
   85 in_localaddr(in)
   86         struct in_addr in;
   87 {
   88         register u_long i = ntohl(in.s_addr);
   89         register struct in_ifaddr *ia;
   90 
   91         if (subnetsarelocal) {
   92                 for (ia = in_ifaddr; ia; ia = ia->ia_next)
   93                         if ((i & ia->ia_netmask) == ia->ia_net)
   94                                 return (1);
   95         } else {
   96                 for (ia = in_ifaddr; ia; ia = ia->ia_next)
   97                         if ((i & ia->ia_subnetmask) == ia->ia_subnet)
   98                                 return (1);
   99         }
  100         return (0);
  101 }
  102 
  103 /*
  104  * Determine whether an IP address is in a reserved set of addresses
  105  * that may not be forwarded, or whether datagrams to that destination
  106  * may be forwarded.
  107  */
  108 int
  109 in_canforward(in)
  110         struct in_addr in;
  111 {
  112         register u_long i = ntohl(in.s_addr);
  113         register u_long net;
  114 
  115         if (IN_EXPERIMENTAL(i) || IN_MULTICAST(i))
  116                 return (0);
  117         if (IN_CLASSA(i)) {
  118                 net = i & IN_CLASSA_NET;
  119                 if (net == 0 || net == (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))
  120                         return (0);
  121         }
  122         return (1);
  123 }
  124 
  125 /*
  126  * Trim a mask in a sockaddr
  127  */
  128 static void
  129 in_socktrim(ap)
  130 struct sockaddr_in *ap;
  131 {
  132     register char *cplim = (char *) &ap->sin_addr;
  133     register char *cp = (char *) (&ap->sin_addr + 1);
  134 
  135     ap->sin_len = 0;
  136     while (--cp >= cplim)
  137         if (*cp) {
  138             (ap)->sin_len = cp - (char *) (ap) + 1;
  139             break;
  140         }
  141 }
  142 
  143 static int in_interfaces;       /* number of external internet interfaces */
  144 
  145 /*
  146  * Generic internet control operations (ioctl's).
  147  * Ifp is 0 if not an interface-specific ioctl.
  148  */
  149 /* ARGSUSED */
  150 int
  151 in_control(so, cmd, data, ifp)
  152         struct socket *so;
  153         u_long cmd;
  154         caddr_t data;
  155         register struct ifnet *ifp;
  156 {
  157         register struct ifreq *ifr = (struct ifreq *)data;
  158         register struct in_ifaddr *ia = 0, *iap;
  159         register struct ifaddr *ifa;
  160         struct in_ifaddr *oia;
  161         struct in_aliasreq *ifra = (struct in_aliasreq *)data;
  162         struct sockaddr_in oldaddr;
  163         int error, hostIsNew, maskIsNew, s;
  164         u_long i;
  165         struct multi_kludge *mk;
  166 
  167         /*
  168          * Find address for this interface, if it exists.
  169          *
  170          * If an alias address was specified, find that one instead of
  171          * the first one on the interface.
  172          */
  173         if (ifp)
  174                 for (iap = in_ifaddr; iap; iap = iap->ia_next)
  175                         if (iap->ia_ifp == ifp) {
  176                                 if (((struct sockaddr_in *)&ifr->ifr_addr)->sin_addr.s_addr ==
  177                                     iap->ia_addr.sin_addr.s_addr) {
  178                                         ia = iap;
  179                                         break;
  180                                 } else if (ia == NULL) {
  181                                         ia = iap;
  182                                         if (ifr->ifr_addr.sa_family != AF_INET)
  183                                                 break;
  184                                 }
  185                         }
  186 
  187         switch (cmd) {
  188 
  189         case SIOCAIFADDR:
  190         case SIOCDIFADDR:
  191                 if (ifp == 0)
  192                         return (EADDRNOTAVAIL);
  193                 if (ifra->ifra_addr.sin_family == AF_INET) {
  194                         for (oia = ia; ia; ia = ia->ia_next) {
  195                                 if (ia->ia_ifp == ifp  &&
  196                                     ia->ia_addr.sin_addr.s_addr ==
  197                                     ifra->ifra_addr.sin_addr.s_addr)
  198                                         break;
  199                         }
  200                         if ((ifp->if_flags & IFF_POINTOPOINT)
  201                             && (cmd == SIOCAIFADDR)
  202                             && (ifra->ifra_dstaddr.sin_addr.s_addr
  203                                 == INADDR_ANY)) {
  204                                 return EDESTADDRREQ;
  205                         }
  206                 }
  207                 if (cmd == SIOCDIFADDR && ia == 0)
  208                         return (EADDRNOTAVAIL);
  209                 /* FALLTHROUGH */
  210         case SIOCSIFADDR:
  211         case SIOCSIFNETMASK:
  212         case SIOCSIFDSTADDR:
  213                 if ((so->so_state & SS_PRIV) == 0)
  214                         return (EPERM);
  215 
  216                 if (ifp == 0)
  217                         return (EADDRNOTAVAIL);
  218                 if (ia == (struct in_ifaddr *)0) {
  219                         oia = (struct in_ifaddr *)
  220                                 malloc(sizeof *oia, M_IFADDR, M_WAITOK);
  221                         if (oia == (struct in_ifaddr *)NULL)
  222                                 return (ENOBUFS);
  223                         bzero((caddr_t)oia, sizeof *oia);
  224                         ia = in_ifaddr;
  225                         /*
  226                          * Protect from ipintr() traversing address list
  227                          * while we're modifying it.
  228                          */
  229                         s = splnet();
  230 
  231                         if (ia) {
  232                                 for ( ; ia->ia_next; ia = ia->ia_next)
  233                                         continue;
  234                                 ia->ia_next = oia;
  235                         } else
  236                                 in_ifaddr = oia;
  237                         ia = oia;
  238                         ifa = ifp->if_addrlist;
  239                         if (ifa) {
  240                                 for ( ; ifa->ifa_next; ifa = ifa->ifa_next)
  241                                         continue;
  242                                 ifa->ifa_next = (struct ifaddr *) ia;
  243                         } else
  244                                 ifp->if_addrlist = (struct ifaddr *) ia;
  245                         ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
  246                         ia->ia_ifa.ifa_dstaddr
  247                                         = (struct sockaddr *)&ia->ia_dstaddr;
  248                         ia->ia_ifa.ifa_netmask
  249                                         = (struct sockaddr *)&ia->ia_sockmask;
  250                         ia->ia_sockmask.sin_len = 8;
  251                         if (ifp->if_flags & IFF_BROADCAST) {
  252                                 ia->ia_broadaddr.sin_len = sizeof(ia->ia_addr);
  253                                 ia->ia_broadaddr.sin_family = AF_INET;
  254                         }
  255                         ia->ia_ifp = ifp;
  256                         if (!(ifp->if_flags & IFF_LOOPBACK))
  257                                 in_interfaces++;
  258                         splx(s);
  259                 }
  260                 break;
  261 
  262         case SIOCSIFBRDADDR:
  263                 if ((so->so_state & SS_PRIV) == 0)
  264                         return (EPERM);
  265                 /* FALLTHROUGH */
  266 
  267         case SIOCGIFADDR:
  268         case SIOCGIFNETMASK:
  269         case SIOCGIFDSTADDR:
  270         case SIOCGIFBRDADDR:
  271                 if (ia == (struct in_ifaddr *)0)
  272                         return (EADDRNOTAVAIL);
  273                 break;
  274         }
  275         switch (cmd) {
  276 
  277         case SIOCGIFADDR:
  278                 *((struct sockaddr_in *)&ifr->ifr_addr) = ia->ia_addr;
  279                 break;
  280 
  281         case SIOCGIFBRDADDR:
  282                 if ((ifp->if_flags & IFF_BROADCAST) == 0)
  283                         return (EINVAL);
  284                 *((struct sockaddr_in *)&ifr->ifr_dstaddr) = ia->ia_broadaddr;
  285                 break;
  286 
  287         case SIOCGIFDSTADDR:
  288                 if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
  289                         return (EINVAL);
  290                 *((struct sockaddr_in *)&ifr->ifr_dstaddr) = ia->ia_dstaddr;
  291                 break;
  292 
  293         case SIOCGIFNETMASK:
  294                 *((struct sockaddr_in *)&ifr->ifr_addr) = ia->ia_sockmask;
  295                 break;
  296 
  297         case SIOCSIFDSTADDR:
  298                 if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
  299                         return (EINVAL);
  300                 oldaddr = ia->ia_dstaddr;
  301                 ia->ia_dstaddr = *(struct sockaddr_in *)&ifr->ifr_dstaddr;
  302                 if (ifp->if_ioctl && (error = (*ifp->if_ioctl)
  303                                         (ifp, SIOCSIFDSTADDR, (caddr_t)ia))) {
  304                         ia->ia_dstaddr = oldaddr;
  305                         return (error);
  306                 }
  307                 if (ia->ia_flags & IFA_ROUTE) {
  308                         ia->ia_ifa.ifa_dstaddr = (struct sockaddr *)&oldaddr;
  309                         rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST);
  310                         ia->ia_ifa.ifa_dstaddr =
  311                                         (struct sockaddr *)&ia->ia_dstaddr;
  312                         rtinit(&(ia->ia_ifa), (int)RTM_ADD, RTF_HOST|RTF_UP);
  313                 }
  314                 break;
  315 
  316         case SIOCSIFBRDADDR:
  317                 if ((ifp->if_flags & IFF_BROADCAST) == 0)
  318                         return (EINVAL);
  319                 ia->ia_broadaddr = *(struct sockaddr_in *)&ifr->ifr_broadaddr;
  320                 break;
  321 
  322         case SIOCSIFADDR:
  323                 return (in_ifinit(ifp, ia,
  324                     (struct sockaddr_in *) &ifr->ifr_addr, 1));
  325 
  326         case SIOCSIFNETMASK:
  327                 i = ifra->ifra_addr.sin_addr.s_addr;
  328                 ia->ia_subnetmask = ntohl(ia->ia_sockmask.sin_addr.s_addr = i);
  329                 break;
  330 
  331         case SIOCAIFADDR:
  332                 maskIsNew = 0;
  333                 hostIsNew = 1;
  334                 error = 0;
  335                 if (ia->ia_addr.sin_family == AF_INET) {
  336                         if (ifra->ifra_addr.sin_len == 0) {
  337                                 ifra->ifra_addr = ia->ia_addr;
  338                                 hostIsNew = 0;
  339                         } else if (ifra->ifra_addr.sin_addr.s_addr ==
  340                                                ia->ia_addr.sin_addr.s_addr)
  341                                 hostIsNew = 0;
  342                 }
  343                 if (ifra->ifra_mask.sin_len) {
  344                         in_ifscrub(ifp, ia);
  345                         ia->ia_sockmask = ifra->ifra_mask;
  346                         ia->ia_subnetmask =
  347                              ntohl(ia->ia_sockmask.sin_addr.s_addr);
  348                         maskIsNew = 1;
  349                 }
  350                 if ((ifp->if_flags & IFF_POINTOPOINT) &&
  351                     (ifra->ifra_dstaddr.sin_family == AF_INET)) {
  352                         in_ifscrub(ifp, ia);
  353                         ia->ia_dstaddr = ifra->ifra_dstaddr;
  354                         maskIsNew  = 1; /* We lie; but the effect's the same */
  355                 }
  356                 if (ifra->ifra_addr.sin_family == AF_INET &&
  357                     (hostIsNew || maskIsNew))
  358                         error = in_ifinit(ifp, ia, &ifra->ifra_addr, 0);
  359                 if ((ifp->if_flags & IFF_BROADCAST) &&
  360                     (ifra->ifra_broadaddr.sin_family == AF_INET))
  361                         ia->ia_broadaddr = ifra->ifra_broadaddr;
  362                 return (error);
  363 
  364         case SIOCDIFADDR:
  365                 mk = malloc(sizeof *mk, M_IPMADDR, M_WAITOK);
  366                 if (!mk)
  367                         return ENOBUFS;
  368 
  369                 in_ifscrub(ifp, ia);
  370                 /*
  371                  * Protect from ipintr() traversing address list
  372                  * while we're modifying it.
  373                  */
  374                 s = splnet();
  375 
  376                 if ((ifa = ifp->if_addrlist) == (struct ifaddr *)ia)
  377                         ifp->if_addrlist = ifa->ifa_next;
  378                 else {
  379                         while (ifa->ifa_next &&
  380                                (ifa->ifa_next != (struct ifaddr *)ia))
  381                                     ifa = ifa->ifa_next;
  382                         if (ifa->ifa_next)
  383                                 ifa->ifa_next = ((struct ifaddr *)ia)->ifa_next;
  384                         else
  385                                 printf("Couldn't unlink inifaddr from ifp\n");
  386                 }
  387                 oia = ia;
  388                 if (oia == (ia = in_ifaddr))
  389                         in_ifaddr = ia->ia_next;
  390                 else {
  391                         while (ia->ia_next && (ia->ia_next != oia))
  392                                 ia = ia->ia_next;
  393                         if (ia->ia_next)
  394                                 ia->ia_next = oia->ia_next;
  395                         else
  396                                 printf("Didn't unlink inifadr from list\n");
  397                 }
  398 
  399                 if (!oia->ia_multiaddrs.lh_first) {
  400                         IFAFREE(&oia->ia_ifa);
  401                         FREE(mk, M_IPMADDR);
  402                         splx(s);
  403                         break;
  404                 }
  405 
  406                 /*
  407                  * Multicast address kludge:
  408                  * If there were any multicast addresses attached to this
  409                  * interface address, either move them to another address
  410                  * on this interface, or save them until such time as this
  411                  * interface is reconfigured for IP.
  412                  */
  413                 IFP_TO_IA(oia->ia_ifp, ia);
  414                 if (ia) {       /* there is another address */
  415                         struct in_multi *inm;
  416                         for(inm = oia->ia_multiaddrs.lh_first; inm;
  417                             inm = inm->inm_entry.le_next) {
  418                                 IFAFREE(&inm->inm_ia->ia_ifa);
  419                                 ia->ia_ifa.ifa_refcnt++;
  420                                 inm->inm_ia = ia;
  421                                 LIST_INSERT_HEAD(&ia->ia_multiaddrs, inm,
  422                                                  inm_entry);
  423                         }
  424                         FREE(mk, M_IPMADDR);
  425                 } else {        /* last address on this if deleted, save */
  426                         struct in_multi *inm;
  427 
  428                         LIST_INIT(&mk->mk_head);
  429                         mk->mk_ifp = ifp;
  430 
  431                         for(inm = oia->ia_multiaddrs.lh_first; inm;
  432                             inm = inm->inm_entry.le_next) {
  433                                 LIST_INSERT_HEAD(&mk->mk_head, inm, inm_entry);
  434                         }
  435 
  436                         if (mk->mk_head.lh_first) {
  437                                 LIST_INSERT_HEAD(&in_mk, mk, mk_entry);
  438                         } else {
  439                                 FREE(mk, M_IPMADDR);
  440                         }
  441                 }
  442 
  443                 IFAFREE((&oia->ia_ifa));
  444                 splx(s);
  445                 break;
  446 
  447         default:
  448                 if (ifp == 0 || ifp->if_ioctl == 0)
  449                         return (EOPNOTSUPP);
  450                 return ((*ifp->if_ioctl)(ifp, cmd, data));
  451         }
  452         return (0);
  453 }
  454 
  455 /*
  456  * Delete any existing route for an interface.
  457  */
  458 static void
  459 in_ifscrub(ifp, ia)
  460         register struct ifnet *ifp;
  461         register struct in_ifaddr *ia;
  462 {
  463 
  464         if ((ia->ia_flags & IFA_ROUTE) == 0)
  465                 return;
  466         if (ifp->if_flags & (IFF_LOOPBACK|IFF_POINTOPOINT))
  467                 rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST);
  468         else
  469                 rtinit(&(ia->ia_ifa), (int)RTM_DELETE, 0);
  470         ia->ia_flags &= ~IFA_ROUTE;
  471 }
  472 
  473 /*
  474  * Initialize an interface's internet address
  475  * and routing table entry.
  476  */
  477 static int
  478 in_ifinit(ifp, ia, sin, scrub)
  479         register struct ifnet *ifp;
  480         register struct in_ifaddr *ia;
  481         struct sockaddr_in *sin;
  482         int scrub;
  483 {
  484         register u_long i = ntohl(sin->sin_addr.s_addr);
  485         struct sockaddr_in oldaddr;
  486         int s = splimp(), flags = RTF_UP, error;
  487         struct multi_kludge *mk;
  488 
  489         oldaddr = ia->ia_addr;
  490         ia->ia_addr = *sin;
  491         /*
  492          * Give the interface a chance to initialize
  493          * if this is its first address,
  494          * and to validate the address if necessary.
  495          */
  496         if (ifp->if_ioctl &&
  497             (error = (*ifp->if_ioctl)(ifp, SIOCSIFADDR, (caddr_t)ia))) {
  498                 splx(s);
  499                 ia->ia_addr = oldaddr;
  500                 return (error);
  501         }
  502         splx(s);
  503         if (scrub) {
  504                 ia->ia_ifa.ifa_addr = (struct sockaddr *)&oldaddr;
  505                 in_ifscrub(ifp, ia);
  506                 ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
  507         }
  508         if (IN_CLASSA(i))
  509                 ia->ia_netmask = IN_CLASSA_NET;
  510         else if (IN_CLASSB(i))
  511                 ia->ia_netmask = IN_CLASSB_NET;
  512         else
  513                 ia->ia_netmask = IN_CLASSC_NET;
  514         /*
  515          * The subnet mask usually includes at least the standard network part,
  516          * but may may be smaller in the case of supernetting.
  517          * If it is set, we believe it.
  518          */
  519         if (ia->ia_subnetmask == 0) {
  520                 ia->ia_subnetmask = ia->ia_netmask;
  521                 ia->ia_sockmask.sin_addr.s_addr = htonl(ia->ia_subnetmask);
  522         } else
  523                 ia->ia_netmask &= ia->ia_subnetmask;
  524         ia->ia_net = i & ia->ia_netmask;
  525         ia->ia_subnet = i & ia->ia_subnetmask;
  526         in_socktrim(&ia->ia_sockmask);
  527         /*
  528          * Add route for the network.
  529          */
  530         ia->ia_ifa.ifa_metric = ifp->if_metric;
  531         if (ifp->if_flags & IFF_BROADCAST) {
  532                 ia->ia_broadaddr.sin_addr.s_addr =
  533                         htonl(ia->ia_subnet | ~ia->ia_subnetmask);
  534                 ia->ia_netbroadcast.s_addr =
  535                         htonl(ia->ia_net | ~ ia->ia_netmask);
  536         } else if (ifp->if_flags & IFF_LOOPBACK) {
  537                 ia->ia_ifa.ifa_dstaddr = ia->ia_ifa.ifa_addr;
  538                 flags |= RTF_HOST;
  539         } else if (ifp->if_flags & IFF_POINTOPOINT) {
  540                 if (ia->ia_dstaddr.sin_family != AF_INET)
  541                         return (0);
  542                 flags |= RTF_HOST;
  543         }
  544         if ((error = rtinit(&(ia->ia_ifa), (int)RTM_ADD, flags)) == 0)
  545                 ia->ia_flags |= IFA_ROUTE;
  546 
  547         LIST_INIT(&ia->ia_multiaddrs);
  548         /*
  549          * If the interface supports multicast, join the "all hosts"
  550          * multicast group on that interface.
  551          */
  552         if (ifp->if_flags & IFF_MULTICAST) {
  553                 struct in_addr addr;
  554 
  555                 /*
  556                  * Continuation of multicast address hack:
  557                  * If there was a multicast group list previously saved
  558                  * for this interface, then we re-attach it to the first
  559                  * address configured on the i/f.
  560                  */
  561                 for(mk = in_mk.lh_first; mk; mk = mk->mk_entry.le_next) {
  562                         if(mk->mk_ifp == ifp) {
  563                                 struct in_multi *inm;
  564 
  565                                 for(inm = mk->mk_head.lh_first; inm;
  566                                     inm = inm->inm_entry.le_next) {
  567                                         IFAFREE(&inm->inm_ia->ia_ifa);
  568                                         ia->ia_ifa.ifa_refcnt++;
  569                                         inm->inm_ia = ia;
  570                                         LIST_INSERT_HEAD(&ia->ia_multiaddrs,
  571                                                          inm, inm_entry);
  572                                 }
  573                                 LIST_REMOVE(mk, mk_entry);
  574                                 free(mk, M_IPMADDR);
  575                                 break;
  576                         }
  577                 }
  578 
  579                 addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
  580                 in_addmulti(&addr, ifp);
  581         }
  582         return (error);
  583 }
  584 
  585 
  586 /*
  587  * Return 1 if the address might be a local broadcast address.
  588  */
  589 int
  590 in_broadcast(in, ifp)
  591         struct in_addr in;
  592         struct ifnet *ifp;
  593 {
  594         register struct ifaddr *ifa;
  595         u_long t;
  596 
  597         if (in.s_addr == INADDR_BROADCAST ||
  598             in.s_addr == INADDR_ANY)
  599                 return 1;
  600         if ((ifp->if_flags & IFF_BROADCAST) == 0)
  601                 return 0;
  602         t = ntohl(in.s_addr);
  603         /*
  604          * Look through the list of addresses for a match
  605          * with a broadcast address.
  606          */
  607 #define ia ((struct in_ifaddr *)ifa)
  608         for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next)
  609                 if (ifa->ifa_addr->sa_family == AF_INET &&
  610                     (in.s_addr == ia->ia_broadaddr.sin_addr.s_addr ||
  611                      in.s_addr == ia->ia_netbroadcast.s_addr ||
  612                      /*
  613                       * Check for old-style (host 0) broadcast.
  614                       */
  615                      t == ia->ia_subnet || t == ia->ia_net) &&
  616                      /*
  617                       * Check for an all one subnetmask. These
  618                       * only exist when an interface gets a secondary
  619                       * address.
  620                       */
  621                      ia->ia_subnetmask != (u_long)0xffffffff)
  622                             return 1;
  623         return (0);
  624 #undef ia
  625 }
  626 /*
  627  * Add an address to the list of IP multicast addresses for a given interface.
  628  */
  629 struct in_multi *
  630 in_addmulti(ap, ifp)
  631         register struct in_addr *ap;
  632         register struct ifnet *ifp;
  633 {
  634         register struct in_multi *inm;
  635         struct ifreq ifr;
  636         struct in_ifaddr *ia;
  637         int s = splnet();
  638 
  639         /*
  640          * See if address already in list.
  641          */
  642         IN_LOOKUP_MULTI(*ap, ifp, inm);
  643         if (inm != NULL) {
  644                 /*
  645                  * Found it; just increment the reference count.
  646                  */
  647                 ++inm->inm_refcount;
  648         }
  649         else {
  650                 /*
  651                  * New address; allocate a new multicast record
  652                  * and link it into the interface's multicast list.
  653                  */
  654                 inm = (struct in_multi *)malloc(sizeof(*inm),
  655                     M_IPMADDR, M_NOWAIT);
  656                 if (inm == NULL) {
  657                         splx(s);
  658                         return (NULL);
  659                 }
  660                 inm->inm_addr = *ap;
  661                 inm->inm_ifp = ifp;
  662                 inm->inm_refcount = 1;
  663                 IFP_TO_IA(ifp, ia);
  664                 if (ia == NULL) {
  665                         free(inm, M_IPMADDR);
  666                         splx(s);
  667                         return (NULL);
  668                 }
  669                 inm->inm_ia = ia;
  670                 ia->ia_ifa.ifa_refcnt++; /* gain a reference */
  671                 LIST_INSERT_HEAD(&ia->ia_multiaddrs, inm, inm_entry);
  672 
  673                 /*
  674                  * Ask the network driver to update its multicast reception
  675                  * filter appropriately for the new address.
  676                  */
  677                 ((struct sockaddr_in *)&ifr.ifr_addr)->sin_family = AF_INET;
  678                 ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr = *ap;
  679                 if ((ifp->if_ioctl == NULL) ||
  680                     (*ifp->if_ioctl)(ifp, SIOCADDMULTI,(caddr_t)&ifr) != 0) {
  681                         LIST_REMOVE(inm, inm_entry);
  682                         IFAFREE(&ia->ia_ifa); /* release reference */
  683                         free(inm, M_IPMADDR);
  684                         splx(s);
  685                         return (NULL);
  686                 }
  687                 /*
  688                  * Let IGMP know that we have joined a new IP multicast group.
  689                  */
  690                 igmp_joingroup(inm);
  691         }
  692         splx(s);
  693         return (inm);
  694 }
  695 
  696 /*
  697  * Delete a multicast address record.
  698  */
  699 void
  700 in_delmulti(inm)
  701         register struct in_multi *inm;
  702 {
  703         struct ifreq ifr;
  704         int s = splnet();
  705 
  706         if (--inm->inm_refcount == 0) {
  707                 /*
  708                  * No remaining claims to this record; let IGMP know that
  709                  * we are leaving the multicast group.
  710                  */
  711                 igmp_leavegroup(inm);
  712                 /*
  713                  * Unlink from list.
  714                  */
  715                 LIST_REMOVE(inm, inm_entry);
  716                 IFAFREE(&inm->inm_ia->ia_ifa); /* release reference */
  717 
  718                 /*
  719                  * Notify the network driver to update its multicast reception
  720                  * filter.
  721                  */
  722                 ((struct sockaddr_in *)&(ifr.ifr_addr))->sin_family = AF_INET;
  723                 ((struct sockaddr_in *)&(ifr.ifr_addr))->sin_addr =
  724                                                                 inm->inm_addr;
  725                 (*inm->inm_ifp->if_ioctl)(inm->inm_ifp, SIOCDELMULTI,
  726                                                              (caddr_t)&ifr);
  727                 free(inm, M_IPMADDR);
  728         }
  729         splx(s);
  730 }

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