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

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1990, 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  *      @(#)ip_output.c 8.3 (Berkeley) 1/21/94
   30  * $FreeBSD: releng/6.4/sys/netinet/ip_output.c 167338 2007-03-08 13:19:03Z bms $
   31  */
   32 
   33 #include "opt_ipfw.h"
   34 #include "opt_ipsec.h"
   35 #include "opt_mac.h"
   36 #include "opt_mbuf_stress_test.h"
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/kernel.h>
   41 #include <sys/mac.h>
   42 #include <sys/malloc.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/protosw.h>
   45 #include <sys/socket.h>
   46 #include <sys/socketvar.h>
   47 #include <sys/sysctl.h>
   48 
   49 #include <net/if.h>
   50 #include <net/netisr.h>
   51 #include <net/pfil.h>
   52 #include <net/route.h>
   53 
   54 #include <netinet/in.h>
   55 #include <netinet/in_systm.h>
   56 #include <netinet/ip.h>
   57 #include <netinet/in_pcb.h>
   58 #include <netinet/in_var.h>
   59 #include <netinet/ip_var.h>
   60 
   61 #include <machine/in_cksum.h>
   62 
   63 static MALLOC_DEFINE(M_IPMOPTS, "ip_moptions", "internet multicast options");
   64 
   65 #ifdef IPSEC
   66 #include <netinet6/ipsec.h>
   67 #include <netkey/key.h>
   68 #ifdef IPSEC_DEBUG
   69 #include <netkey/key_debug.h>
   70 #else
   71 #define KEYDEBUG(lev,arg)
   72 #endif
   73 #endif /*IPSEC*/
   74 
   75 #ifdef FAST_IPSEC
   76 #include <netipsec/ipsec.h>
   77 #include <netipsec/xform.h>
   78 #include <netipsec/key.h>
   79 #endif /*FAST_IPSEC*/
   80 
   81 #define print_ip(x, a, y)        printf("%s %d.%d.%d.%d%s",\
   82                                 x, (ntohl(a.s_addr)>>24)&0xFF,\
   83                                   (ntohl(a.s_addr)>>16)&0xFF,\
   84                                   (ntohl(a.s_addr)>>8)&0xFF,\
   85                                   (ntohl(a.s_addr))&0xFF, y);
   86 
   87 u_short ip_id;
   88 
   89 #ifdef MBUF_STRESS_TEST
   90 int mbuf_frag_size = 0;
   91 SYSCTL_INT(_net_inet_ip, OID_AUTO, mbuf_frag_size, CTLFLAG_RW,
   92         &mbuf_frag_size, 0, "Fragment outgoing mbufs to this size");
   93 #endif
   94 
   95 static struct mbuf *ip_insertoptions(struct mbuf *, struct mbuf *, int *);
   96 static struct ifnet *ip_multicast_if(struct in_addr *, int *);
   97 static void     ip_mloopback
   98         (struct ifnet *, struct mbuf *, struct sockaddr_in *, int);
   99 static int      ip_getmoptions(struct inpcb *, struct sockopt *);
  100 static int      ip_pcbopts(struct inpcb *, int, struct mbuf *);
  101 static int      ip_setmoptions(struct inpcb *, struct sockopt *);
  102 static struct ip_moptions       *ip_findmoptions(struct inpcb *inp);
  103 
  104 int     ip_optcopy(struct ip *, struct ip *);
  105 
  106 
  107 extern  struct protosw inetsw[];
  108 
  109 /*
  110  * IP output.  The packet in mbuf chain m contains a skeletal IP
  111  * header (with len, off, ttl, proto, tos, src, dst).
  112  * The mbuf chain containing the packet will be freed.
  113  * The mbuf opt, if present, will not be freed.
  114  * In the IP forwarding case, the packet will arrive with options already
  115  * inserted, so must have a NULL opt pointer.
  116  */
  117 int
  118 ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro,
  119         int flags, struct ip_moptions *imo, struct inpcb *inp)
  120 {
  121         struct ip *ip;
  122         struct ifnet *ifp = NULL;       /* keep compiler happy */
  123         struct mbuf *m0;
  124         int hlen = sizeof (struct ip);
  125         int len, error = 0;
  126         struct sockaddr_in *dst = NULL; /* keep compiler happy */
  127         struct in_ifaddr *ia = NULL;
  128         int isbroadcast, sw_csum;
  129         struct route iproute;
  130         struct in_addr odst;
  131 #ifdef IPFIREWALL_FORWARD
  132         struct m_tag *fwd_tag = NULL;
  133 #endif
  134 #ifdef IPSEC
  135         struct secpolicy *sp = NULL;
  136 #endif
  137 #ifdef FAST_IPSEC
  138         struct secpolicy *sp = NULL;
  139         struct tdb_ident *tdbi;
  140         struct m_tag *mtag;
  141         int s;
  142 #endif /* FAST_IPSEC */
  143 
  144         M_ASSERTPKTHDR(m);
  145         
  146         if (ro == NULL) {
  147                 ro = &iproute;
  148                 bzero(ro, sizeof (*ro));
  149         }
  150 
  151         if (inp != NULL)
  152                 INP_LOCK_ASSERT(inp);
  153 
  154         if (opt) {
  155                 len = 0;
  156                 m = ip_insertoptions(m, opt, &len);
  157                 if (len != 0)
  158                         hlen = len;
  159         }
  160         ip = mtod(m, struct ip *);
  161 
  162         /*
  163          * Fill in IP header.  If we are not allowing fragmentation,
  164          * then the ip_id field is meaningless, but we don't set it
  165          * to zero.  Doing so causes various problems when devices along
  166          * the path (routers, load balancers, firewalls, etc.) illegally
  167          * disable DF on our packet.  Note that a 16-bit counter
  168          * will wrap around in less than 10 seconds at 100 Mbit/s on a
  169          * medium with MTU 1500.  See Steven M. Bellovin, "A Technique
  170          * for Counting NATted Hosts", Proc. IMW'02, available at
  171          * <http://www.cs.columbia.edu/~smb/papers/fnat.pdf>.
  172          */
  173         if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
  174                 ip->ip_v = IPVERSION;
  175                 ip->ip_hl = hlen >> 2;
  176                 ip->ip_id = ip_newid();
  177                 ipstat.ips_localout++;
  178         } else {
  179                 hlen = ip->ip_hl << 2;
  180         }
  181 
  182         dst = (struct sockaddr_in *)&ro->ro_dst;
  183 again:
  184         /*
  185          * If there is a cached route,
  186          * check that it is to the same destination
  187          * and is still up.  If not, free it and try again.
  188          * The address family should also be checked in case of sharing the
  189          * cache with IPv6.
  190          */
  191         if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
  192                           dst->sin_family != AF_INET ||
  193                           dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
  194                 RTFREE(ro->ro_rt);
  195                 ro->ro_rt = (struct rtentry *)0;
  196         }
  197 #ifdef IPFIREWALL_FORWARD
  198         if (ro->ro_rt == NULL && fwd_tag == NULL) {
  199 #else
  200         if (ro->ro_rt == NULL) {
  201 #endif
  202                 bzero(dst, sizeof(*dst));
  203                 dst->sin_family = AF_INET;
  204                 dst->sin_len = sizeof(*dst);
  205                 dst->sin_addr = ip->ip_dst;
  206         }
  207         /*
  208          * If routing to interface only, short circuit routing lookup.
  209          * The use of an all-ones broadcast address implies this; an
  210          * interface is specified by the broadcast address of an interface,
  211          * or the destination address of a ptp interface.
  212          */
  213         if (flags & IP_SENDONES) {
  214                 if ((ia = ifatoia(ifa_ifwithbroadaddr(sintosa(dst)))) == NULL &&
  215                     (ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL) {
  216                         ipstat.ips_noroute++;
  217                         error = ENETUNREACH;
  218                         goto bad;
  219                 }
  220                 ip->ip_dst.s_addr = INADDR_BROADCAST;
  221                 dst->sin_addr = ip->ip_dst;
  222                 ifp = ia->ia_ifp;
  223                 ip->ip_ttl = 1;
  224                 isbroadcast = 1;
  225         } else if (flags & IP_ROUTETOIF) {
  226                 if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
  227                     (ia = ifatoia(ifa_ifwithnet(sintosa(dst)))) == NULL) {
  228                         ipstat.ips_noroute++;
  229                         error = ENETUNREACH;
  230                         goto bad;
  231                 }
  232                 ifp = ia->ia_ifp;
  233                 ip->ip_ttl = 1;
  234                 isbroadcast = in_broadcast(dst->sin_addr, ifp);
  235         } else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) &&
  236             imo != NULL && imo->imo_multicast_ifp != NULL) {
  237                 /*
  238                  * Bypass the normal routing lookup for multicast
  239                  * packets if the interface is specified.
  240                  */
  241                 ifp = imo->imo_multicast_ifp;
  242                 IFP_TO_IA(ifp, ia);
  243                 isbroadcast = 0;        /* fool gcc */
  244         } else {
  245                 /*
  246                  * We want to do any cloning requested by the link layer,
  247                  * as this is probably required in all cases for correct
  248                  * operation (as it is for ARP).
  249                  */
  250                 if (ro->ro_rt == NULL)
  251                         rtalloc_ign(ro, 0);
  252                 if (ro->ro_rt == NULL) {
  253                         ipstat.ips_noroute++;
  254                         error = EHOSTUNREACH;
  255                         goto bad;
  256                 }
  257                 ia = ifatoia(ro->ro_rt->rt_ifa);
  258                 ifp = ro->ro_rt->rt_ifp;
  259                 ro->ro_rt->rt_rmx.rmx_pksent++;
  260                 if (ro->ro_rt->rt_flags & RTF_GATEWAY)
  261                         dst = (struct sockaddr_in *)ro->ro_rt->rt_gateway;
  262                 if (ro->ro_rt->rt_flags & RTF_HOST)
  263                         isbroadcast = (ro->ro_rt->rt_flags & RTF_BROADCAST);
  264                 else
  265                         isbroadcast = in_broadcast(dst->sin_addr, ifp);
  266         }
  267         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
  268                 struct in_multi *inm;
  269 
  270                 m->m_flags |= M_MCAST;
  271                 /*
  272                  * IP destination address is multicast.  Make sure "dst"
  273                  * still points to the address in "ro".  (It may have been
  274                  * changed to point to a gateway address, above.)
  275                  */
  276                 dst = (struct sockaddr_in *)&ro->ro_dst;
  277                 /*
  278                  * See if the caller provided any multicast options
  279                  */
  280                 if (imo != NULL) {
  281                         ip->ip_ttl = imo->imo_multicast_ttl;
  282                         if (imo->imo_multicast_vif != -1)
  283                                 ip->ip_src.s_addr =
  284                                     ip_mcast_src ?
  285                                     ip_mcast_src(imo->imo_multicast_vif) :
  286                                     INADDR_ANY;
  287                 } else
  288                         ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
  289                 /*
  290                  * Confirm that the outgoing interface supports multicast.
  291                  */
  292                 if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
  293                         if ((ifp->if_flags & IFF_MULTICAST) == 0) {
  294                                 ipstat.ips_noroute++;
  295                                 error = ENETUNREACH;
  296                                 goto bad;
  297                         }
  298                 }
  299                 /*
  300                  * If source address not specified yet, use address
  301                  * of outgoing interface.
  302                  */
  303                 if (ip->ip_src.s_addr == INADDR_ANY) {
  304                         /* Interface may have no addresses. */
  305                         if (ia != NULL)
  306                                 ip->ip_src = IA_SIN(ia)->sin_addr;
  307                 }
  308 
  309                 IN_MULTI_LOCK();
  310                 IN_LOOKUP_MULTI(ip->ip_dst, ifp, inm);
  311                 if (inm != NULL &&
  312                    (imo == NULL || imo->imo_multicast_loop)) {
  313                         IN_MULTI_UNLOCK();
  314                         /*
  315                          * If we belong to the destination multicast group
  316                          * on the outgoing interface, and the caller did not
  317                          * forbid loopback, loop back a copy.
  318                          */
  319                         ip_mloopback(ifp, m, dst, hlen);
  320                 }
  321                 else {
  322                         IN_MULTI_UNLOCK();
  323                         /*
  324                          * If we are acting as a multicast router, perform
  325                          * multicast forwarding as if the packet had just
  326                          * arrived on the interface to which we are about
  327                          * to send.  The multicast forwarding function
  328                          * recursively calls this function, using the
  329                          * IP_FORWARDING flag to prevent infinite recursion.
  330                          *
  331                          * Multicasts that are looped back by ip_mloopback(),
  332                          * above, will be forwarded by the ip_input() routine,
  333                          * if necessary.
  334                          */
  335                         if (ip_mrouter && (flags & IP_FORWARDING) == 0) {
  336                                 /*
  337                                  * If rsvp daemon is not running, do not
  338                                  * set ip_moptions. This ensures that the packet
  339                                  * is multicast and not just sent down one link
  340                                  * as prescribed by rsvpd.
  341                                  */
  342                                 if (!rsvp_on)
  343                                         imo = NULL;
  344                                 if (ip_mforward &&
  345                                     ip_mforward(ip, ifp, m, imo) != 0) {
  346                                         m_freem(m);
  347                                         goto done;
  348                                 }
  349                         }
  350                 }
  351 
  352                 /*
  353                  * Multicasts with a time-to-live of zero may be looped-
  354                  * back, above, but must not be transmitted on a network.
  355                  * Also, multicasts addressed to the loopback interface
  356                  * are not sent -- the above call to ip_mloopback() will
  357                  * loop back a copy if this host actually belongs to the
  358                  * destination group on the loopback interface.
  359                  */
  360                 if (ip->ip_ttl == 0 || ifp->if_flags & IFF_LOOPBACK) {
  361                         m_freem(m);
  362                         goto done;
  363                 }
  364 
  365                 goto sendit;
  366         }
  367 #ifndef notdef
  368         /*
  369          * If the source address is not specified yet, use the address
  370          * of the outoing interface.
  371          */
  372         if (ip->ip_src.s_addr == INADDR_ANY) {
  373                 /* Interface may have no addresses. */
  374                 if (ia != NULL) {
  375                         ip->ip_src = IA_SIN(ia)->sin_addr;
  376                 }
  377         }
  378 #endif /* notdef */
  379         /*
  380          * Verify that we have any chance at all of being able to queue the
  381          * packet or packet fragments, unless ALTQ is enabled on the given
  382          * interface in which case packetdrop should be done by queueing.
  383          */
  384 #ifdef ALTQ
  385         if ((!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
  386             ((ifp->if_snd.ifq_len + ip->ip_len / ifp->if_mtu + 1) >=
  387             ifp->if_snd.ifq_maxlen))
  388 #else
  389         if ((ifp->if_snd.ifq_len + ip->ip_len / ifp->if_mtu + 1) >=
  390             ifp->if_snd.ifq_maxlen)
  391 #endif /* ALTQ */
  392         {
  393                 error = ENOBUFS;
  394                 ipstat.ips_odropped++;
  395                 ifp->if_snd.ifq_drops += (ip->ip_len / ifp->if_mtu + 1);
  396                 goto bad;
  397         }
  398 
  399         /*
  400          * Look for broadcast address and
  401          * verify user is allowed to send
  402          * such a packet.
  403          */
  404         if (isbroadcast) {
  405                 if ((ifp->if_flags & IFF_BROADCAST) == 0) {
  406                         error = EADDRNOTAVAIL;
  407                         goto bad;
  408                 }
  409                 if ((flags & IP_ALLOWBROADCAST) == 0) {
  410                         error = EACCES;
  411                         goto bad;
  412                 }
  413                 /* don't allow broadcast messages to be fragmented */
  414                 if (ip->ip_len > ifp->if_mtu) {
  415                         error = EMSGSIZE;
  416                         goto bad;
  417                 }
  418                 m->m_flags |= M_BCAST;
  419         } else {
  420                 m->m_flags &= ~M_BCAST;
  421         }
  422 
  423 sendit:
  424 #ifdef IPSEC
  425         /* get SP for this packet */
  426         if (inp == NULL)
  427                 sp = ipsec4_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
  428                     flags, &error);
  429         else
  430                 sp = ipsec4_getpolicybypcb(m, IPSEC_DIR_OUTBOUND, inp, &error);
  431 
  432         if (sp == NULL) {
  433                 ipsecstat.out_inval++;
  434                 goto bad;
  435         }
  436 
  437         error = 0;
  438 
  439         /* check policy */
  440         switch (sp->policy) {
  441         case IPSEC_POLICY_DISCARD:
  442                 /*
  443                  * This packet is just discarded.
  444                  */
  445                 ipsecstat.out_polvio++;
  446                 goto bad;
  447 
  448         case IPSEC_POLICY_BYPASS:
  449         case IPSEC_POLICY_NONE:
  450         case IPSEC_POLICY_TCP:
  451                 /* no need to do IPsec. */
  452                 goto skip_ipsec;
  453         
  454         case IPSEC_POLICY_IPSEC:
  455                 if (sp->req == NULL) {
  456                         /* acquire a policy */
  457                         error = key_spdacquire(sp);
  458                         goto bad;
  459                 }
  460                 break;
  461 
  462         case IPSEC_POLICY_ENTRUST:
  463         default:
  464                 printf("ip_output: Invalid policy found. %d\n", sp->policy);
  465         }
  466     {
  467         struct ipsec_output_state state;
  468         bzero(&state, sizeof(state));
  469         state.m = m;
  470         if (flags & IP_ROUTETOIF) {
  471                 state.ro = &iproute;
  472                 bzero(&iproute, sizeof(iproute));
  473         } else
  474                 state.ro = ro;
  475         state.dst = (struct sockaddr *)dst;
  476 
  477         ip->ip_sum = 0;
  478 
  479         /*
  480          * XXX
  481          * delayed checksums are not currently compatible with IPsec
  482          */
  483         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  484                 in_delayed_cksum(m);
  485                 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  486         }
  487 
  488         ip->ip_len = htons(ip->ip_len);
  489         ip->ip_off = htons(ip->ip_off);
  490 
  491         error = ipsec4_output(&state, sp, flags);
  492 
  493         m = state.m;
  494         if (flags & IP_ROUTETOIF) {
  495                 /*
  496                  * if we have tunnel mode SA, we may need to ignore
  497                  * IP_ROUTETOIF.
  498                  */
  499                 if (state.ro != &iproute || state.ro->ro_rt != NULL) {
  500                         flags &= ~IP_ROUTETOIF;
  501                         ro = state.ro;
  502                 }
  503         } else
  504                 ro = state.ro;
  505         dst = (struct sockaddr_in *)state.dst;
  506         if (error) {
  507                 /* mbuf is already reclaimed in ipsec4_output. */
  508                 m = NULL;
  509                 switch (error) {
  510                 case EHOSTUNREACH:
  511                 case ENETUNREACH:
  512                 case EMSGSIZE:
  513                 case ENOBUFS:
  514                 case ENOMEM:
  515                         break;
  516                 default:
  517                         printf("ip4_output (ipsec): error code %d\n", error);
  518                         /*fall through*/
  519                 case ENOENT:
  520                         /* don't show these error codes to the user */
  521                         error = 0;
  522                         break;
  523                 }
  524                 goto bad;
  525         }
  526 
  527         /* be sure to update variables that are affected by ipsec4_output() */
  528         ip = mtod(m, struct ip *);
  529         hlen = ip->ip_hl << 2;
  530         if (ro->ro_rt == NULL) {
  531                 if ((flags & IP_ROUTETOIF) == 0) {
  532                         printf("ip_output: "
  533                                 "can't update route after IPsec processing\n");
  534                         error = EHOSTUNREACH;   /*XXX*/
  535                         goto bad;
  536                 }
  537         } else {
  538                 if (state.encap) {
  539                         ia = ifatoia(ro->ro_rt->rt_ifa);
  540                         ifp = ro->ro_rt->rt_ifp;
  541                 }
  542         }
  543     }
  544 
  545         /* make it flipped, again. */
  546         ip->ip_len = ntohs(ip->ip_len);
  547         ip->ip_off = ntohs(ip->ip_off);
  548 skip_ipsec:
  549 #endif /*IPSEC*/
  550 #ifdef FAST_IPSEC
  551         /*
  552          * Check the security policy (SP) for the packet and, if
  553          * required, do IPsec-related processing.  There are two
  554          * cases here; the first time a packet is sent through
  555          * it will be untagged and handled by ipsec4_checkpolicy.
  556          * If the packet is resubmitted to ip_output (e.g. after
  557          * AH, ESP, etc. processing), there will be a tag to bypass
  558          * the lookup and related policy checking.
  559          */
  560         mtag = m_tag_find(m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
  561         s = splnet();
  562         if (mtag != NULL) {
  563                 tdbi = (struct tdb_ident *)(mtag + 1);
  564                 sp = ipsec_getpolicy(tdbi, IPSEC_DIR_OUTBOUND);
  565                 if (sp == NULL)
  566                         error = -EINVAL;        /* force silent drop */
  567                 m_tag_delete(m, mtag);
  568         } else {
  569                 sp = ipsec4_checkpolicy(m, IPSEC_DIR_OUTBOUND, flags,
  570                                         &error, inp);
  571         }
  572         /*
  573          * There are four return cases:
  574          *    sp != NULL                    apply IPsec policy
  575          *    sp == NULL, error == 0        no IPsec handling needed
  576          *    sp == NULL, error == -EINVAL  discard packet w/o error
  577          *    sp == NULL, error != 0        discard packet, report error
  578          */
  579         if (sp != NULL) {
  580                 /* Loop detection, check if ipsec processing already done */
  581                 KASSERT(sp->req != NULL, ("ip_output: no ipsec request"));
  582                 for (mtag = m_tag_first(m); mtag != NULL;
  583                      mtag = m_tag_next(m, mtag)) {
  584                         if (mtag->m_tag_cookie != MTAG_ABI_COMPAT)
  585                                 continue;
  586                         if (mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_DONE &&
  587                             mtag->m_tag_id != PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED)
  588                                 continue;
  589                         /*
  590                          * Check if policy has an SA associated with it.
  591                          * This can happen when an SP has yet to acquire
  592                          * an SA; e.g. on first reference.  If it occurs,
  593                          * then we let ipsec4_process_packet do its thing.
  594                          */
  595                         if (sp->req->sav == NULL)
  596                                 break;
  597                         tdbi = (struct tdb_ident *)(mtag + 1);
  598                         if (tdbi->spi == sp->req->sav->spi &&
  599                             tdbi->proto == sp->req->sav->sah->saidx.proto &&
  600                             bcmp(&tdbi->dst, &sp->req->sav->sah->saidx.dst,
  601                                  sizeof (union sockaddr_union)) == 0) {
  602                                 /*
  603                                  * No IPsec processing is needed, free
  604                                  * reference to SP.
  605                                  *
  606                                  * NB: null pointer to avoid free at
  607                                  *     done: below.
  608                                  */
  609                                 KEY_FREESP(&sp), sp = NULL;
  610                                 splx(s);
  611                                 goto spd_done;
  612                         }
  613                 }
  614 
  615                 /*
  616                  * Do delayed checksums now because we send before
  617                  * this is done in the normal processing path.
  618                  */
  619                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  620                         in_delayed_cksum(m);
  621                         m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  622                 }
  623 
  624                 ip->ip_len = htons(ip->ip_len);
  625                 ip->ip_off = htons(ip->ip_off);
  626 
  627                 /* NB: callee frees mbuf */
  628                 error = ipsec4_process_packet(m, sp->req, flags, 0);
  629                 /*
  630                  * Preserve KAME behaviour: ENOENT can be returned
  631                  * when an SA acquire is in progress.  Don't propagate
  632                  * this to user-level; it confuses applications.
  633                  *
  634                  * XXX this will go away when the SADB is redone.
  635                  */
  636                 if (error == ENOENT)
  637                         error = 0;
  638                 splx(s);
  639                 goto done;
  640         } else {
  641                 splx(s);
  642 
  643                 if (error != 0) {
  644                         /*
  645                          * Hack: -EINVAL is used to signal that a packet
  646                          * should be silently discarded.  This is typically
  647                          * because we asked key management for an SA and
  648                          * it was delayed (e.g. kicked up to IKE).
  649                          */
  650                         if (error == -EINVAL)
  651                                 error = 0;
  652                         goto bad;
  653                 } else {
  654                         /* No IPsec processing for this packet. */
  655                 }
  656 #ifdef notyet
  657                 /*
  658                  * If deferred crypto processing is needed, check that
  659                  * the interface supports it.
  660                  */ 
  661                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED, NULL);
  662                 if (mtag != NULL && (ifp->if_capenable & IFCAP_IPSEC) == 0) {
  663                         /* notify IPsec to do its own crypto */
  664                         ipsp_skipcrypto_unmark((struct tdb_ident *)(mtag + 1));
  665                         error = EHOSTUNREACH;
  666                         goto bad;
  667                 }
  668 #endif
  669         }
  670 spd_done:
  671 #endif /* FAST_IPSEC */
  672 
  673         /* Jump over all PFIL processing if hooks are not active. */
  674         if (inet_pfil_hook.ph_busy_count == -1)
  675                 goto passout;
  676 
  677         /* Run through list of hooks for output packets. */
  678         odst.s_addr = ip->ip_dst.s_addr;
  679         error = pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT, inp);
  680         if (error != 0 || m == NULL)
  681                 goto done;
  682 
  683         ip = mtod(m, struct ip *);
  684 
  685         /* See if destination IP address was changed by packet filter. */
  686         if (odst.s_addr != ip->ip_dst.s_addr) {
  687                 m->m_flags |= M_SKIP_FIREWALL;
  688                 /* If destination is now ourself drop to ip_input(). */
  689                 if (in_localip(ip->ip_dst)) {
  690                         m->m_flags |= M_FASTFWD_OURS;
  691                         if (m->m_pkthdr.rcvif == NULL)
  692                                 m->m_pkthdr.rcvif = loif;
  693                         if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  694                                 m->m_pkthdr.csum_flags |=
  695                                     CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
  696                                 m->m_pkthdr.csum_data = 0xffff;
  697                         }
  698                         m->m_pkthdr.csum_flags |=
  699                             CSUM_IP_CHECKED | CSUM_IP_VALID;
  700 
  701                         error = netisr_queue(NETISR_IP, m);
  702                         goto done;
  703                 } else
  704                         goto again;     /* Redo the routing table lookup. */
  705         }
  706 
  707 #ifdef IPFIREWALL_FORWARD
  708         /* See if local, if yes, send it to netisr with IP_FASTFWD_OURS. */
  709         if (m->m_flags & M_FASTFWD_OURS) {
  710                 if (m->m_pkthdr.rcvif == NULL)
  711                         m->m_pkthdr.rcvif = loif;
  712                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
  713                         m->m_pkthdr.csum_flags |=
  714                             CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
  715                         m->m_pkthdr.csum_data = 0xffff;
  716                 }
  717                 m->m_pkthdr.csum_flags |=
  718                             CSUM_IP_CHECKED | CSUM_IP_VALID;
  719 
  720                 error = netisr_queue(NETISR_IP, m);
  721                 goto done;
  722         }
  723         /* Or forward to some other address? */
  724         fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
  725         if (fwd_tag) {
  726                 dst = (struct sockaddr_in *)&ro->ro_dst;
  727                 bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in));
  728                 m->m_flags |= M_SKIP_FIREWALL;
  729                 m_tag_delete(m, fwd_tag);
  730                 goto again;
  731         }
  732 #endif /* IPFIREWALL_FORWARD */
  733 
  734 passout:
  735         /* 127/8 must not appear on wire - RFC1122. */
  736         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
  737             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
  738                 if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
  739                         ipstat.ips_badaddr++;
  740                         error = EADDRNOTAVAIL;
  741                         goto bad;
  742                 }
  743         }
  744 
  745         m->m_pkthdr.csum_flags |= CSUM_IP;
  746         sw_csum = m->m_pkthdr.csum_flags & ~ifp->if_hwassist;
  747         if (sw_csum & CSUM_DELAY_DATA) {
  748                 in_delayed_cksum(m);
  749                 sw_csum &= ~CSUM_DELAY_DATA;
  750         }
  751         m->m_pkthdr.csum_flags &= ifp->if_hwassist;
  752 
  753         /*
  754          * If small enough for interface, or the interface will take
  755          * care of the fragmentation for us, can just send directly.
  756          */
  757         if (ip->ip_len <= ifp->if_mtu || (ifp->if_hwassist & CSUM_FRAGMENT &&
  758             ((ip->ip_off & IP_DF) == 0))) {
  759                 ip->ip_len = htons(ip->ip_len);
  760                 ip->ip_off = htons(ip->ip_off);
  761                 ip->ip_sum = 0;
  762                 if (sw_csum & CSUM_DELAY_IP)
  763                         ip->ip_sum = in_cksum(m, hlen);
  764 
  765                 /* Record statistics for this interface address. */
  766                 if (!(flags & IP_FORWARDING) && ia) {
  767                         ia->ia_ifa.if_opackets++;
  768                         ia->ia_ifa.if_obytes += m->m_pkthdr.len;
  769                 }
  770 
  771 #ifdef IPSEC
  772                 /* clean ipsec history once it goes out of the node */
  773                 ipsec_delaux(m);
  774 #endif
  775 
  776 #ifdef MBUF_STRESS_TEST
  777                 if (mbuf_frag_size && m->m_pkthdr.len > mbuf_frag_size)
  778                         m = m_fragment(m, M_DONTWAIT, mbuf_frag_size);
  779 #endif
  780                 error = (*ifp->if_output)(ifp, m,
  781                                 (struct sockaddr *)dst, ro->ro_rt);
  782                 goto done;
  783         }
  784 
  785         if (ip->ip_off & IP_DF) {
  786                 error = EMSGSIZE;
  787                 /*
  788                  * This case can happen if the user changed the MTU
  789                  * of an interface after enabling IP on it.  Because
  790                  * most netifs don't keep track of routes pointing to
  791                  * them, there is no way for one to update all its
  792                  * routes when the MTU is changed.
  793                  */
  794                 if (ro != NULL &&
  795                     (ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) &&
  796                     (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)) {
  797                         ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
  798                 }
  799                 ipstat.ips_cantfrag++;
  800                 goto bad;
  801         }
  802 
  803         /*
  804          * Too large for interface; fragment if possible. If successful,
  805          * on return, m will point to a list of packets to be sent.
  806          */
  807         error = ip_fragment(ip, &m, ifp->if_mtu, ifp->if_hwassist, sw_csum);
  808         if (error)
  809                 goto bad;
  810         for (; m; m = m0) {
  811                 m0 = m->m_nextpkt;
  812                 m->m_nextpkt = 0;
  813 #ifdef IPSEC
  814                 /* clean ipsec history once it goes out of the node */
  815                 ipsec_delaux(m);
  816 #endif
  817                 if (error == 0) {
  818                         /* Record statistics for this interface address. */
  819                         if (ia != NULL) {
  820                                 ia->ia_ifa.if_opackets++;
  821                                 ia->ia_ifa.if_obytes += m->m_pkthdr.len;
  822                         }
  823                         
  824                         error = (*ifp->if_output)(ifp, m,
  825                             (struct sockaddr *)dst, ro->ro_rt);
  826                 } else
  827                         m_freem(m);
  828         }
  829 
  830         if (error == 0)
  831                 ipstat.ips_fragmented++;
  832 
  833 done:
  834         if (ro == &iproute && ro->ro_rt) {
  835                 RTFREE(ro->ro_rt);
  836         }
  837 #ifdef IPSEC
  838         if (sp != NULL) {
  839                 KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
  840                         printf("DP ip_output call free SP:%p\n", sp));
  841                 key_freesp(sp);
  842         }
  843 #endif
  844 #ifdef FAST_IPSEC
  845         if (sp != NULL)
  846                 KEY_FREESP(&sp);
  847 #endif
  848         return (error);
  849 bad:
  850         m_freem(m);
  851         goto done;
  852 }
  853 
  854 /*
  855  * Create a chain of fragments which fit the given mtu. m_frag points to the
  856  * mbuf to be fragmented; on return it points to the chain with the fragments.
  857  * Return 0 if no error. If error, m_frag may contain a partially built
  858  * chain of fragments that should be freed by the caller.
  859  *
  860  * if_hwassist_flags is the hw offload capabilities (see if_data.ifi_hwassist)
  861  * sw_csum contains the delayed checksums flags (e.g., CSUM_DELAY_IP).
  862  */
  863 int
  864 ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
  865             u_long if_hwassist_flags, int sw_csum)
  866 {
  867         int error = 0;
  868         int hlen = ip->ip_hl << 2;
  869         int len = (mtu - hlen) & ~7;    /* size of payload in each fragment */
  870         int off;
  871         struct mbuf *m0 = *m_frag;      /* the original packet          */
  872         int firstlen;
  873         struct mbuf **mnext;
  874         int nfrags;
  875 
  876         if (ip->ip_off & IP_DF) {       /* Fragmentation not allowed */
  877                 ipstat.ips_cantfrag++;
  878                 return EMSGSIZE;
  879         }
  880 
  881         /*
  882          * Must be able to put at least 8 bytes per fragment.
  883          */
  884         if (len < 8)
  885                 return EMSGSIZE;
  886 
  887         /*
  888          * If the interface will not calculate checksums on
  889          * fragmented packets, then do it here.
  890          */
  891         if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA &&
  892             (if_hwassist_flags & CSUM_IP_FRAGS) == 0) {
  893                 in_delayed_cksum(m0);
  894                 m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
  895         }
  896 
  897         if (len > PAGE_SIZE) {
  898                 /* 
  899                  * Fragment large datagrams such that each segment 
  900                  * contains a multiple of PAGE_SIZE amount of data, 
  901                  * plus headers. This enables a receiver to perform 
  902                  * page-flipping zero-copy optimizations.
  903                  *
  904                  * XXX When does this help given that sender and receiver
  905                  * could have different page sizes, and also mtu could
  906                  * be less than the receiver's page size ?
  907                  */
  908                 int newlen;
  909                 struct mbuf *m;
  910 
  911                 for (m = m0, off = 0; m && (off+m->m_len) <= mtu; m = m->m_next)
  912                         off += m->m_len;
  913 
  914                 /*
  915                  * firstlen (off - hlen) must be aligned on an 
  916                  * 8-byte boundary
  917                  */
  918                 if (off < hlen)
  919                         goto smart_frag_failure;
  920                 off = ((off - hlen) & ~7) + hlen;
  921                 newlen = (~PAGE_MASK) & mtu;
  922                 if ((newlen + sizeof (struct ip)) > mtu) {
  923                         /* we failed, go back the default */
  924 smart_frag_failure:
  925                         newlen = len;
  926                         off = hlen + len;
  927                 }
  928                 len = newlen;
  929 
  930         } else {
  931                 off = hlen + len;
  932         }
  933 
  934         firstlen = off - hlen;
  935         mnext = &m0->m_nextpkt;         /* pointer to next packet */
  936 
  937         /*
  938          * Loop through length of segment after first fragment,
  939          * make new header and copy data of each part and link onto chain.
  940          * Here, m0 is the original packet, m is the fragment being created.
  941          * The fragments are linked off the m_nextpkt of the original
  942          * packet, which after processing serves as the first fragment.
  943          */
  944         for (nfrags = 1; off < ip->ip_len; off += len, nfrags++) {
  945                 struct ip *mhip;        /* ip header on the fragment */
  946                 struct mbuf *m;
  947                 int mhlen = sizeof (struct ip);
  948 
  949                 MGETHDR(m, M_DONTWAIT, MT_HEADER);
  950                 if (m == NULL) {
  951                         error = ENOBUFS;
  952                         ipstat.ips_odropped++;
  953                         goto done;
  954                 }
  955                 m->m_flags |= (m0->m_flags & M_MCAST) | M_FRAG;
  956                 /*
  957                  * In the first mbuf, leave room for the link header, then
  958                  * copy the original IP header including options. The payload
  959                  * goes into an additional mbuf chain returned by m_copy().
  960                  */
  961                 m->m_data += max_linkhdr;
  962                 mhip = mtod(m, struct ip *);
  963                 *mhip = *ip;
  964                 if (hlen > sizeof (struct ip)) {
  965                         mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
  966                         mhip->ip_v = IPVERSION;
  967                         mhip->ip_hl = mhlen >> 2;
  968                 }
  969                 m->m_len = mhlen;
  970                 /* XXX do we need to add ip->ip_off below ? */
  971                 mhip->ip_off = ((off - hlen) >> 3) + ip->ip_off;
  972                 if (off + len >= ip->ip_len) {  /* last fragment */
  973                         len = ip->ip_len - off;
  974                         m->m_flags |= M_LASTFRAG;
  975                 } else
  976                         mhip->ip_off |= IP_MF;
  977                 mhip->ip_len = htons((u_short)(len + mhlen));
  978                 m->m_next = m_copy(m0, off, len);
  979                 if (m->m_next == NULL) {        /* copy failed */
  980                         m_free(m);
  981                         error = ENOBUFS;        /* ??? */
  982                         ipstat.ips_odropped++;
  983                         goto done;
  984                 }
  985                 m->m_pkthdr.len = mhlen + len;
  986                 m->m_pkthdr.rcvif = NULL;
  987 #ifdef MAC
  988                 mac_create_fragment(m0, m);
  989 #endif
  990                 m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
  991                 mhip->ip_off = htons(mhip->ip_off);
  992                 mhip->ip_sum = 0;
  993                 if (sw_csum & CSUM_DELAY_IP)
  994                         mhip->ip_sum = in_cksum(m, mhlen);
  995                 *mnext = m;
  996                 mnext = &m->m_nextpkt;
  997         }
  998         ipstat.ips_ofragments += nfrags;
  999 
 1000         /* set first marker for fragment chain */
 1001         m0->m_flags |= M_FIRSTFRAG | M_FRAG;
 1002         m0->m_pkthdr.csum_data = nfrags;
 1003 
 1004         /*
 1005          * Update first fragment by trimming what's been copied out
 1006          * and updating header.
 1007          */
 1008         m_adj(m0, hlen + firstlen - ip->ip_len);
 1009         m0->m_pkthdr.len = hlen + firstlen;
 1010         ip->ip_len = htons((u_short)m0->m_pkthdr.len);
 1011         ip->ip_off |= IP_MF;
 1012         ip->ip_off = htons(ip->ip_off);
 1013         ip->ip_sum = 0;
 1014         if (sw_csum & CSUM_DELAY_IP)
 1015                 ip->ip_sum = in_cksum(m0, hlen);
 1016 
 1017 done:
 1018         *m_frag = m0;
 1019         return error;
 1020 }
 1021 
 1022 void
 1023 in_delayed_cksum(struct mbuf *m)
 1024 {
 1025         struct ip *ip;
 1026         u_short csum, offset;
 1027 
 1028         ip = mtod(m, struct ip *);
 1029         offset = ip->ip_hl << 2 ;
 1030         csum = in_cksum_skip(m, ip->ip_len, offset);
 1031         if (m->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
 1032                 csum = 0xffff;
 1033         offset += m->m_pkthdr.csum_data;        /* checksum offset */
 1034 
 1035         if (offset + sizeof(u_short) > m->m_len) {
 1036                 printf("delayed m_pullup, m->len: %d  off: %d  p: %d\n",
 1037                     m->m_len, offset, ip->ip_p);
 1038                 /*
 1039                  * XXX
 1040                  * this shouldn't happen, but if it does, the
 1041                  * correct behavior may be to insert the checksum
 1042                  * in the appropriate next mbuf in the chain.
 1043                  */
 1044                 return;
 1045         }
 1046         *(u_short *)(m->m_data + offset) = csum;
 1047 }
 1048 
 1049 /*
 1050  * Insert IP options into preformed packet.
 1051  * Adjust IP destination as required for IP source routing,
 1052  * as indicated by a non-zero in_addr at the start of the options.
 1053  *
 1054  * XXX This routine assumes that the packet has no options in place.
 1055  */
 1056 static struct mbuf *
 1057 ip_insertoptions(m, opt, phlen)
 1058         register struct mbuf *m;
 1059         struct mbuf *opt;
 1060         int *phlen;
 1061 {
 1062         register struct ipoption *p = mtod(opt, struct ipoption *);
 1063         struct mbuf *n;
 1064         register struct ip *ip = mtod(m, struct ip *);
 1065         unsigned optlen;
 1066 
 1067         optlen = opt->m_len - sizeof(p->ipopt_dst);
 1068         if (optlen + ip->ip_len > IP_MAXPACKET) {
 1069                 *phlen = 0;
 1070                 return (m);             /* XXX should fail */
 1071         }
 1072         if (p->ipopt_dst.s_addr)
 1073                 ip->ip_dst = p->ipopt_dst;
 1074         if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
 1075                 MGETHDR(n, M_DONTWAIT, MT_HEADER);
 1076                 if (n == NULL) {
 1077                         *phlen = 0;
 1078                         return (m);
 1079                 }
 1080                 M_MOVE_PKTHDR(n, m);
 1081                 n->m_pkthdr.rcvif = NULL;
 1082 #ifdef MAC
 1083                 mac_copy_mbuf(m, n);
 1084 #endif
 1085                 n->m_pkthdr.len += optlen;
 1086                 m->m_len -= sizeof(struct ip);
 1087                 m->m_data += sizeof(struct ip);
 1088                 n->m_next = m;
 1089                 m = n;
 1090                 m->m_len = optlen + sizeof(struct ip);
 1091                 m->m_data += max_linkhdr;
 1092                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 1093         } else {
 1094                 m->m_data -= optlen;
 1095                 m->m_len += optlen;
 1096                 m->m_pkthdr.len += optlen;
 1097                 bcopy(ip, mtod(m, void *), sizeof(struct ip));
 1098         }
 1099         ip = mtod(m, struct ip *);
 1100         bcopy(p->ipopt_list, ip + 1, optlen);
 1101         *phlen = sizeof(struct ip) + optlen;
 1102         ip->ip_v = IPVERSION;
 1103         ip->ip_hl = *phlen >> 2;
 1104         ip->ip_len += optlen;
 1105         return (m);
 1106 }
 1107 
 1108 /*
 1109  * Copy options from ip to jp,
 1110  * omitting those not copied during fragmentation.
 1111  */
 1112 int
 1113 ip_optcopy(ip, jp)
 1114         struct ip *ip, *jp;
 1115 {
 1116         register u_char *cp, *dp;
 1117         int opt, optlen, cnt;
 1118 
 1119         cp = (u_char *)(ip + 1);
 1120         dp = (u_char *)(jp + 1);
 1121         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
 1122         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 1123                 opt = cp[0];
 1124                 if (opt == IPOPT_EOL)
 1125                         break;
 1126                 if (opt == IPOPT_NOP) {
 1127                         /* Preserve for IP mcast tunnel's LSRR alignment. */
 1128                         *dp++ = IPOPT_NOP;
 1129                         optlen = 1;
 1130                         continue;
 1131                 }
 1132 
 1133                 KASSERT(cnt >= IPOPT_OLEN + sizeof(*cp),
 1134                     ("ip_optcopy: malformed ipv4 option"));
 1135                 optlen = cp[IPOPT_OLEN];
 1136                 KASSERT(optlen >= IPOPT_OLEN + sizeof(*cp) && optlen <= cnt,
 1137                     ("ip_optcopy: malformed ipv4 option"));
 1138 
 1139                 /* bogus lengths should have been caught by ip_dooptions */
 1140                 if (optlen > cnt)
 1141                         optlen = cnt;
 1142                 if (IPOPT_COPIED(opt)) {
 1143                         bcopy(cp, dp, optlen);
 1144                         dp += optlen;
 1145                 }
 1146         }
 1147         for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
 1148                 *dp++ = IPOPT_EOL;
 1149         return (optlen);
 1150 }
 1151 
 1152 /*
 1153  * IP socket option processing.
 1154  *
 1155  * There are two versions of this call in order to work around a race
 1156  * condition in TCP in FreeBSD 6.x.  In the TCP implementation, so->so_pcb
 1157  * can become NULL if the pcb or pcbinfo lock isn't held.  However, when
 1158  * entering ip_ctloutput(), neither lock is held, and finding the pointer to
 1159  * either lock requires follow so->so_pcb, which may be NULL.
 1160  * ip_ctloutput_pcbinfo() accepts the pcbinfo pointer so that the lock can be
 1161  * safely acquired.  This is not required in FreeBSD 7.x because the
 1162  * invariants on so->so_pcb are much stronger, so it cannot become NULL
 1163  * while the socket is in use.
 1164  */
 1165 int
 1166 ip_ctloutput_pcbinfo(so, sopt, pcbinfo)
 1167         struct socket *so;
 1168         struct sockopt *sopt;
 1169         struct inpcbinfo *pcbinfo;
 1170 {
 1171         struct  inpcb *inp = sotoinpcb(so);
 1172         int     error, optval;
 1173 
 1174         if (pcbinfo == NULL)
 1175                 pcbinfo = inp->inp_pcbinfo;
 1176 
 1177         error = optval = 0;
 1178         if (sopt->sopt_level != IPPROTO_IP) {
 1179                 return (EINVAL);
 1180         }
 1181 
 1182         if (inp == NULL)
 1183                 return (EINVAL);
 1184 
 1185         switch (sopt->sopt_dir) {
 1186         case SOPT_SET:
 1187                 switch (sopt->sopt_name) {
 1188                 case IP_OPTIONS:
 1189 #ifdef notyet
 1190                 case IP_RETOPTS:
 1191 #endif
 1192                 {
 1193                         struct mbuf *m;
 1194                         if (sopt->sopt_valsize > MLEN) {
 1195                                 error = EMSGSIZE;
 1196                                 break;
 1197                         }
 1198                         MGET(m, sopt->sopt_td ? M_TRYWAIT : M_DONTWAIT, MT_DATA);
 1199                         if (m == NULL) {
 1200                                 error = ENOBUFS;
 1201                                 break;
 1202                         }
 1203                         m->m_len = sopt->sopt_valsize;
 1204                         error = sooptcopyin(sopt, mtod(m, char *), m->m_len,
 1205                                             m->m_len);
 1206                         if (error) {
 1207                                 m_free(m);
 1208                                 break;
 1209                         }
 1210                         INP_INFO_WLOCK(pcbinfo);
 1211                         if (so->so_pcb == NULL) {
 1212                                 INP_INFO_WUNLOCK(pcbinfo);
 1213                                 m_free(m);
 1214                                 error = EINVAL;
 1215                                 break;
 1216                         }
 1217                         INP_LOCK(inp);
 1218                         INP_INFO_WUNLOCK(pcbinfo);
 1219                         error = ip_pcbopts(inp, sopt->sopt_name, m);
 1220                         INP_UNLOCK(inp);
 1221                         return (error);
 1222                 }
 1223 
 1224                 case IP_TOS:
 1225                 case IP_TTL:
 1226                 case IP_MINTTL:
 1227                 case IP_RECVOPTS:
 1228                 case IP_RECVRETOPTS:
 1229                 case IP_RECVDSTADDR:
 1230                 case IP_RECVTTL:
 1231                 case IP_RECVIF:
 1232                 case IP_FAITH:
 1233                 case IP_ONESBCAST:
 1234                 case IP_DONTFRAG:
 1235                         error = sooptcopyin(sopt, &optval, sizeof optval,
 1236                                             sizeof optval);
 1237                         if (error)
 1238                                 break;
 1239 
 1240                         INP_INFO_WLOCK(pcbinfo);
 1241                         if (so->so_pcb == NULL) {
 1242                                 INP_INFO_WUNLOCK(pcbinfo);
 1243                                 error = EINVAL;
 1244                                 break;
 1245                         }
 1246                         INP_LOCK(inp);
 1247                         INP_INFO_WUNLOCK(pcbinfo);
 1248                         switch (sopt->sopt_name) {
 1249                         case IP_TOS:
 1250                                 inp->inp_ip_tos = optval;
 1251                                 break;
 1252 
 1253                         case IP_TTL:
 1254                                 inp->inp_ip_ttl = optval;
 1255                                 break;
 1256 
 1257                         case IP_MINTTL:
 1258                                 if (optval > 0 && optval <= MAXTTL)
 1259                                         inp->inp_ip_minttl = optval;
 1260                                 else
 1261                                         error = EINVAL;
 1262                                 break;
 1263 
 1264 #define OPTSET(bit) do {                                                \
 1265         INP_LOCK(inp);                                                  \
 1266         if (optval)                                                     \
 1267                 inp->inp_flags |= bit;                                  \
 1268         else                                                            \
 1269                 inp->inp_flags &= ~bit;                                 \
 1270         INP_UNLOCK(inp);                                                \
 1271 } while (0)
 1272 
 1273                         case IP_RECVOPTS:
 1274                                 OPTSET(INP_RECVOPTS);
 1275                                 break;
 1276 
 1277                         case IP_RECVRETOPTS:
 1278                                 OPTSET(INP_RECVRETOPTS);
 1279                                 break;
 1280 
 1281                         case IP_RECVDSTADDR:
 1282                                 OPTSET(INP_RECVDSTADDR);
 1283                                 break;
 1284 
 1285                         case IP_RECVTTL:
 1286                                 OPTSET(INP_RECVTTL);
 1287                                 break;
 1288 
 1289                         case IP_RECVIF:
 1290                                 OPTSET(INP_RECVIF);
 1291                                 break;
 1292 
 1293                         case IP_FAITH:
 1294                                 OPTSET(INP_FAITH);
 1295                                 break;
 1296 
 1297                         case IP_ONESBCAST:
 1298                                 OPTSET(INP_ONESBCAST);
 1299                                 break;
 1300                         case IP_DONTFRAG:
 1301                                 OPTSET(INP_DONTFRAG);
 1302                                 break;
 1303                         }
 1304                         INP_UNLOCK(inp);
 1305                         break;
 1306 #undef OPTSET
 1307 
 1308                 case IP_MULTICAST_IF:
 1309                 case IP_MULTICAST_VIF:
 1310                 case IP_MULTICAST_TTL:
 1311                 case IP_MULTICAST_LOOP:
 1312                 case IP_ADD_MEMBERSHIP:
 1313                 case IP_DROP_MEMBERSHIP:
 1314                         error = ip_setmoptions(inp, sopt);
 1315                         break;
 1316 
 1317                 case IP_PORTRANGE:
 1318                         error = sooptcopyin(sopt, &optval, sizeof optval,
 1319                                             sizeof optval);
 1320                         if (error)
 1321                                 break;
 1322 
 1323                         INP_INFO_WLOCK(pcbinfo);
 1324                         if (so->so_pcb == NULL) {
 1325                                 error = EINVAL;
 1326                                 break;
 1327                         }
 1328                         INP_LOCK(inp);
 1329                         INP_INFO_WUNLOCK(pcbinfo);
 1330                         switch (optval) {
 1331                         case IP_PORTRANGE_DEFAULT:
 1332                                 inp->inp_flags &= ~(INP_LOWPORT);
 1333                                 inp->inp_flags &= ~(INP_HIGHPORT);
 1334                                 break;
 1335 
 1336                         case IP_PORTRANGE_HIGH:
 1337                                 inp->inp_flags &= ~(INP_LOWPORT);
 1338                                 inp->inp_flags |= INP_HIGHPORT;
 1339                                 break;
 1340 
 1341                         case IP_PORTRANGE_LOW:
 1342                                 inp->inp_flags &= ~(INP_HIGHPORT);
 1343                                 inp->inp_flags |= INP_LOWPORT;
 1344                                 break;
 1345 
 1346                         default:
 1347                                 error = EINVAL;
 1348                                 break;
 1349                         }
 1350                         INP_UNLOCK(inp);
 1351                         break;
 1352 
 1353 #if defined(IPSEC) || defined(FAST_IPSEC)
 1354                 case IP_IPSEC_POLICY:
 1355                 {
 1356                         caddr_t req;
 1357                         size_t len = 0;
 1358                         int priv;
 1359                         struct mbuf *m;
 1360                         int optname;
 1361 
 1362                         if ((error = soopt_getm(sopt, &m)) != 0) /* XXX */
 1363                                 break;
 1364                         if ((error = soopt_mcopyin(sopt, m)) != 0) /* XXX */
 1365                                 break;
 1366                         priv = (sopt->sopt_td != NULL &&
 1367                                 suser(sopt->sopt_td) != 0) ? 0 : 1;
 1368                         req = mtod(m, caddr_t);
 1369                         len = m->m_len;
 1370                         optname = sopt->sopt_name;
 1371                         if (so->so_pcb == NULL) {
 1372                                 m_free(m);
 1373                                 error = EINVAL;
 1374                                 break;
 1375                         }
 1376                         error = ipsec4_set_policy(inp, optname, req, len, priv);
 1377                         m_freem(m);
 1378                         break;
 1379                 }
 1380 #endif /*IPSEC*/
 1381 
 1382                 default:
 1383                         error = ENOPROTOOPT;
 1384                         break;
 1385                 }
 1386                 break;
 1387 
 1388         case SOPT_GET:
 1389                 switch (sopt->sopt_name) {
 1390                 case IP_OPTIONS:
 1391                 case IP_RETOPTS:
 1392                         if (inp->inp_options)
 1393                                 error = sooptcopyout(sopt, 
 1394                                                      mtod(inp->inp_options,
 1395                                                           char *),
 1396                                                      inp->inp_options->m_len);
 1397                         else
 1398                                 sopt->sopt_valsize = 0;
 1399                         break;
 1400 
 1401                 case IP_TOS:
 1402                 case IP_TTL:
 1403                 case IP_MINTTL:
 1404                 case IP_RECVOPTS:
 1405                 case IP_RECVRETOPTS:
 1406                 case IP_RECVDSTADDR:
 1407                 case IP_RECVTTL:
 1408                 case IP_RECVIF:
 1409                 case IP_PORTRANGE:
 1410                 case IP_FAITH:
 1411                 case IP_ONESBCAST:
 1412                 case IP_DONTFRAG:
 1413                         switch (sopt->sopt_name) {
 1414 
 1415                         case IP_TOS:
 1416                                 optval = inp->inp_ip_tos;
 1417                                 break;
 1418 
 1419                         case IP_TTL:
 1420                                 optval = inp->inp_ip_ttl;
 1421                                 break;
 1422 
 1423                         case IP_MINTTL:
 1424                                 optval = inp->inp_ip_minttl;
 1425                                 break;
 1426 
 1427 #define OPTBIT(bit)     (inp->inp_flags & bit ? 1 : 0)
 1428 
 1429                         case IP_RECVOPTS:
 1430                                 optval = OPTBIT(INP_RECVOPTS);
 1431                                 break;
 1432 
 1433                         case IP_RECVRETOPTS:
 1434                                 optval = OPTBIT(INP_RECVRETOPTS);
 1435                                 break;
 1436 
 1437                         case IP_RECVDSTADDR:
 1438                                 optval = OPTBIT(INP_RECVDSTADDR);
 1439                                 break;
 1440 
 1441                         case IP_RECVTTL:
 1442                                 optval = OPTBIT(INP_RECVTTL);
 1443                                 break;
 1444 
 1445                         case IP_RECVIF:
 1446                                 optval = OPTBIT(INP_RECVIF);
 1447                                 break;
 1448 
 1449                         case IP_PORTRANGE:
 1450                                 if (inp->inp_flags & INP_HIGHPORT)
 1451                                         optval = IP_PORTRANGE_HIGH;
 1452                                 else if (inp->inp_flags & INP_LOWPORT)
 1453                                         optval = IP_PORTRANGE_LOW;
 1454                                 else
 1455                                         optval = 0;
 1456                                 break;
 1457 
 1458                         case IP_FAITH:
 1459                                 optval = OPTBIT(INP_FAITH);
 1460                                 break;
 1461 
 1462                         case IP_ONESBCAST:
 1463                                 optval = OPTBIT(INP_ONESBCAST);
 1464                                 break;
 1465                         case IP_DONTFRAG:
 1466                                 optval = OPTBIT(INP_DONTFRAG);
 1467                                 break;
 1468                         }
 1469                         error = sooptcopyout(sopt, &optval, sizeof optval);
 1470                         break;
 1471 
 1472                 case IP_MULTICAST_IF:
 1473                 case IP_MULTICAST_VIF:
 1474                 case IP_MULTICAST_TTL:
 1475                 case IP_MULTICAST_LOOP:
 1476                 case IP_ADD_MEMBERSHIP:
 1477                 case IP_DROP_MEMBERSHIP:
 1478                         error = ip_getmoptions(inp, sopt);
 1479                         break;
 1480 
 1481 #if defined(IPSEC) || defined(FAST_IPSEC)
 1482                 case IP_IPSEC_POLICY:
 1483                 {
 1484                         struct mbuf *m = NULL;
 1485                         caddr_t req = NULL;
 1486                         size_t len = 0;
 1487 
 1488                         if (m != 0) {
 1489                                 req = mtod(m, caddr_t);
 1490                                 len = m->m_len;
 1491                         }
 1492                         error = ipsec4_get_policy(sotoinpcb(so), req, len, &m);
 1493                         if (error == 0)
 1494                                 error = soopt_mcopyout(sopt, m); /* XXX */
 1495                         if (error == 0)
 1496                                 m_freem(m);
 1497                         break;
 1498                 }
 1499 #endif /*IPSEC*/
 1500 
 1501                 default:
 1502                         error = ENOPROTOOPT;
 1503                         break;
 1504                 }
 1505                 break;
 1506         }
 1507         return (error);
 1508 }
 1509 
 1510 int
 1511 ip_ctloutput(so, sopt)
 1512         struct socket *so;
 1513         struct sockopt *sopt;
 1514 {
 1515 
 1516         return (ip_ctloutput_pcbinfo(so, sopt, NULL));
 1517 }
 1518 
 1519 /*
 1520  * Set up IP options in pcb for insertion in output packets.
 1521  * Store in mbuf with pointer in pcbopt, adding pseudo-option
 1522  * with destination address if source routed.
 1523  */
 1524 static int
 1525 ip_pcbopts(struct inpcb *inp, int optname, struct mbuf *m)
 1526 {
 1527         register int cnt, optlen;
 1528         register u_char *cp;
 1529         struct mbuf **pcbopt;
 1530         u_char opt;
 1531 
 1532         INP_LOCK_ASSERT(inp);
 1533 
 1534         pcbopt = &inp->inp_options;
 1535 
 1536         /* turn off any old options */
 1537         if (*pcbopt)
 1538                 (void)m_free(*pcbopt);
 1539         *pcbopt = 0;
 1540         if (m == NULL || m->m_len == 0) {
 1541                 /*
 1542                  * Only turning off any previous options.
 1543                  */
 1544                 if (m != NULL)
 1545                         (void)m_free(m);
 1546                 return (0);
 1547         }
 1548 
 1549         if (m->m_len % sizeof(int32_t))
 1550                 goto bad;
 1551         /*
 1552          * IP first-hop destination address will be stored before
 1553          * actual options; move other options back
 1554          * and clear it when none present.
 1555          */
 1556         if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
 1557                 goto bad;
 1558         cnt = m->m_len;
 1559         m->m_len += sizeof(struct in_addr);
 1560         cp = mtod(m, u_char *) + sizeof(struct in_addr);
 1561         bcopy(mtod(m, void *), cp, (unsigned)cnt);
 1562         bzero(mtod(m, void *), sizeof(struct in_addr));
 1563 
 1564         for (; cnt > 0; cnt -= optlen, cp += optlen) {
 1565                 opt = cp[IPOPT_OPTVAL];
 1566                 if (opt == IPOPT_EOL)
 1567                         break;
 1568                 if (opt == IPOPT_NOP)
 1569                         optlen = 1;
 1570                 else {
 1571                         if (cnt < IPOPT_OLEN + sizeof(*cp))
 1572                                 goto bad;
 1573                         optlen = cp[IPOPT_OLEN];
 1574                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
 1575                                 goto bad;
 1576                 }
 1577                 switch (opt) {
 1578 
 1579                 default:
 1580                         break;
 1581 
 1582                 case IPOPT_LSRR:
 1583                 case IPOPT_SSRR:
 1584                         /*
 1585                          * user process specifies route as:
 1586                          *      ->A->B->C->D
 1587                          * D must be our final destination (but we can't
 1588                          * check that since we may not have connected yet).
 1589                          * A is first hop destination, which doesn't appear in
 1590                          * actual IP option, but is stored before the options.
 1591                          */
 1592                         if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
 1593                                 goto bad;
 1594                         m->m_len -= sizeof(struct in_addr);
 1595                         cnt -= sizeof(struct in_addr);
 1596                         optlen -= sizeof(struct in_addr);
 1597                         cp[IPOPT_OLEN] = optlen;
 1598                         /*
 1599                          * Move first hop before start of options.
 1600                          */
 1601                         bcopy((caddr_t)&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
 1602                             sizeof(struct in_addr));
 1603                         /*
 1604                          * Then copy rest of options back
 1605                          * to close up the deleted entry.
 1606                          */
 1607                         bcopy((&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr)),
 1608                             &cp[IPOPT_OFFSET+1],
 1609                             (unsigned)cnt - (IPOPT_MINOFF - 1));
 1610                         break;
 1611                 }
 1612         }
 1613         if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
 1614                 goto bad;
 1615         *pcbopt = m;
 1616         return (0);
 1617 
 1618 bad:
 1619         (void)m_free(m);
 1620         return (EINVAL);
 1621 }
 1622 
 1623 /*
 1624  * XXX
 1625  * The whole multicast option thing needs to be re-thought.
 1626  * Several of these options are equally applicable to non-multicast
 1627  * transmission, and one (IP_MULTICAST_TTL) totally duplicates a
 1628  * standard option (IP_TTL).
 1629  */
 1630 
 1631 /*
 1632  * following RFC1724 section 3.3, 0.0.0.0/8 is interpreted as interface index.
 1633  */
 1634 static struct ifnet *
 1635 ip_multicast_if(a, ifindexp)
 1636         struct in_addr *a;
 1637         int *ifindexp;
 1638 {
 1639         int ifindex;
 1640         struct ifnet *ifp;
 1641 
 1642         if (ifindexp)
 1643                 *ifindexp = 0;
 1644         if (ntohl(a->s_addr) >> 24 == 0) {
 1645                 ifindex = ntohl(a->s_addr) & 0xffffff;
 1646                 if (ifindex < 0 || if_index < ifindex)
 1647                         return NULL;
 1648                 ifp = ifnet_byindex(ifindex);
 1649                 if (ifindexp)
 1650                         *ifindexp = ifindex;
 1651         } else {
 1652                 INADDR_TO_IFP(*a, ifp);
 1653         }
 1654         return ifp;
 1655 }
 1656 
 1657 /*
 1658  * Given an inpcb, return its multicast options structure pointer.  Accepts
 1659  * an unlocked inpcb pointer, but will return it locked.  May sleep.
 1660  */
 1661 static struct ip_moptions *
 1662 ip_findmoptions(struct inpcb *inp)
 1663 {
 1664         struct ip_moptions *imo;
 1665 
 1666         INP_LOCK(inp);
 1667         if (inp->inp_moptions != NULL)
 1668                 return (inp->inp_moptions);
 1669 
 1670         INP_UNLOCK(inp);
 1671 
 1672         imo = (struct ip_moptions*)malloc(sizeof(*imo), M_IPMOPTS, M_WAITOK);
 1673 
 1674         imo->imo_multicast_ifp = NULL;
 1675         imo->imo_multicast_addr.s_addr = INADDR_ANY;
 1676         imo->imo_multicast_vif = -1;
 1677         imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
 1678         imo->imo_multicast_loop = IP_DEFAULT_MULTICAST_LOOP;
 1679         imo->imo_num_memberships = 0;
 1680 
 1681         INP_LOCK(inp);
 1682         if (inp->inp_moptions != NULL) {
 1683                 free(imo, M_IPMOPTS);
 1684                 return (inp->inp_moptions);
 1685         }
 1686         inp->inp_moptions = imo;
 1687         return (imo);
 1688 }
 1689 
 1690 /*
 1691  * Set the IP multicast options in response to user setsockopt().
 1692  */
 1693 static int
 1694 ip_setmoptions(struct inpcb *inp, struct sockopt *sopt)
 1695 {
 1696         int error = 0;
 1697         int i;
 1698         struct in_addr addr;
 1699         struct ip_mreq mreq;
 1700         struct ifnet *ifp;
 1701         struct ip_moptions *imo;
 1702         struct route ro;
 1703         struct sockaddr_in *dst;
 1704         int ifindex;
 1705         int s;
 1706 
 1707         switch (sopt->sopt_name) {
 1708         /* store an index number for the vif you wanna use in the send */
 1709         case IP_MULTICAST_VIF:
 1710                 if (legal_vif_num == 0) {
 1711                         error = EOPNOTSUPP;
 1712                         break;
 1713                 }
 1714                 error = sooptcopyin(sopt, &i, sizeof i, sizeof i);
 1715                 if (error)
 1716                         break;
 1717                 if (!legal_vif_num(i) && (i != -1)) {
 1718                         error = EINVAL;
 1719                         break;
 1720                 }
 1721                 imo = ip_findmoptions(inp);
 1722                 imo->imo_multicast_vif = i;
 1723                 INP_UNLOCK(inp);
 1724                 break;
 1725 
 1726         case IP_MULTICAST_IF:
 1727                 /*
 1728                  * Select the interface for outgoing multicast packets.
 1729                  */
 1730                 error = sooptcopyin(sopt, &addr, sizeof addr, sizeof addr);
 1731                 if (error)
 1732                         break;
 1733                 /*
 1734                  * INADDR_ANY is used to remove a previous selection.
 1735                  * When no interface is selected, a default one is
 1736                  * chosen every time a multicast packet is sent.
 1737                  */
 1738                 imo = ip_findmoptions(inp);
 1739                 if (addr.s_addr == INADDR_ANY) {
 1740                         imo->imo_multicast_ifp = NULL;
 1741                         INP_UNLOCK(inp);
 1742                         break;
 1743                 }
 1744                 /*
 1745                  * The selected interface is identified by its local
 1746                  * IP address.  Find the interface and confirm that
 1747                  * it supports multicasting.
 1748                  */
 1749                 s = splimp();
 1750                 ifp = ip_multicast_if(&addr, &ifindex);
 1751                 if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
 1752                         INP_UNLOCK(inp);
 1753                         splx(s);
 1754                         error = EADDRNOTAVAIL;
 1755                         break;
 1756                 }
 1757                 imo->imo_multicast_ifp = ifp;
 1758                 if (ifindex)
 1759                         imo->imo_multicast_addr = addr;
 1760                 else
 1761                         imo->imo_multicast_addr.s_addr = INADDR_ANY;
 1762                 INP_UNLOCK(inp);
 1763                 splx(s);
 1764                 break;
 1765 
 1766         case IP_MULTICAST_TTL:
 1767                 /*
 1768                  * Set the IP time-to-live for outgoing multicast packets.
 1769                  * The original multicast API required a char argument,
 1770                  * which is inconsistent with the rest of the socket API.
 1771                  * We allow either a char or an int.
 1772                  */
 1773                 if (sopt->sopt_valsize == 1) {
 1774                         u_char ttl;
 1775                         error = sooptcopyin(sopt, &ttl, 1, 1);
 1776                         if (error)
 1777                                 break;
 1778                         imo = ip_findmoptions(inp);
 1779                         imo->imo_multicast_ttl = ttl;
 1780                         INP_UNLOCK(inp);
 1781                 } else {
 1782                         u_int ttl;
 1783                         error = sooptcopyin(sopt, &ttl, sizeof ttl, 
 1784                                             sizeof ttl);
 1785                         if (error)
 1786                                 break;
 1787                         if (ttl > 255)
 1788                                 error = EINVAL;
 1789                         else {
 1790                                 imo = ip_findmoptions(inp);
 1791                                 imo->imo_multicast_ttl = ttl;
 1792                                 INP_UNLOCK(inp);
 1793                         }
 1794                 }
 1795                 break;
 1796 
 1797         case IP_MULTICAST_LOOP:
 1798                 /*
 1799                  * Set the loopback flag for outgoing multicast packets.
 1800                  * Must be zero or one.  The original multicast API required a
 1801                  * char argument, which is inconsistent with the rest
 1802                  * of the socket API.  We allow either a char or an int.
 1803                  */
 1804                 if (sopt->sopt_valsize == 1) {
 1805                         u_char loop;
 1806                         error = sooptcopyin(sopt, &loop, 1, 1);
 1807                         if (error)
 1808                                 break;
 1809                         imo = ip_findmoptions(inp);
 1810                         imo->imo_multicast_loop = !!loop;
 1811                         INP_UNLOCK(inp);
 1812                 } else {
 1813                         u_int loop;
 1814                         error = sooptcopyin(sopt, &loop, sizeof loop,
 1815                                             sizeof loop);
 1816                         if (error)
 1817                                 break;
 1818                         imo = ip_findmoptions(inp);
 1819                         imo->imo_multicast_loop = !!loop;
 1820                         INP_UNLOCK(inp);
 1821                 }
 1822                 break;
 1823 
 1824         case IP_ADD_MEMBERSHIP:
 1825                 /*
 1826                  * Add a multicast group membership.
 1827                  * Group must be a valid IP multicast address.
 1828                  */
 1829                 error = sooptcopyin(sopt, &mreq, sizeof mreq, sizeof mreq);
 1830                 if (error)
 1831                         break;
 1832 
 1833                 if (!IN_MULTICAST(ntohl(mreq.imr_multiaddr.s_addr))) {
 1834                         error = EINVAL;
 1835                         break;
 1836                 }
 1837                 s = splimp();
 1838                 /*
 1839                  * If no interface address was provided, use the interface of
 1840                  * the route to the given multicast address.
 1841                  */
 1842                 if (mreq.imr_interface.s_addr == INADDR_ANY) {
 1843                         bzero((caddr_t)&ro, sizeof(ro));
 1844                         dst = (struct sockaddr_in *)&ro.ro_dst;
 1845                         dst->sin_len = sizeof(*dst);
 1846                         dst->sin_family = AF_INET;
 1847                         dst->sin_addr = mreq.imr_multiaddr;
 1848                         rtalloc_ign(&ro, RTF_CLONING);
 1849                         if (ro.ro_rt == NULL) {
 1850                                 error = EADDRNOTAVAIL;
 1851                                 splx(s);
 1852                                 break;
 1853                         }
 1854                         ifp = ro.ro_rt->rt_ifp;
 1855                         RTFREE(ro.ro_rt);
 1856                 }
 1857                 else {
 1858                         ifp = ip_multicast_if(&mreq.imr_interface, NULL);
 1859                 }
 1860 
 1861                 /*
 1862                  * See if we found an interface, and confirm that it
 1863                  * supports multicast.
 1864                  */
 1865                 if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
 1866                         error = EADDRNOTAVAIL;
 1867                         splx(s);
 1868                         break;
 1869                 }
 1870                 /*
 1871                  * See if the membership already exists or if all the
 1872                  * membership slots are full.
 1873                  */
 1874                 imo = ip_findmoptions(inp);
 1875                 for (i = 0; i < imo->imo_num_memberships; ++i) {
 1876                         if (imo->imo_membership[i]->inm_ifp == ifp &&
 1877                             imo->imo_membership[i]->inm_addr.s_addr
 1878                                                 == mreq.imr_multiaddr.s_addr)
 1879                                 break;
 1880                 }
 1881                 if (i < imo->imo_num_memberships) {
 1882                         INP_UNLOCK(inp);
 1883                         error = EADDRINUSE;
 1884                         splx(s);
 1885                         break;
 1886                 }
 1887                 if (i == IP_MAX_MEMBERSHIPS) {
 1888                         INP_UNLOCK(inp);
 1889                         error = ETOOMANYREFS;
 1890                         splx(s);
 1891                         break;
 1892                 }
 1893                 /*
 1894                  * Everything looks good; add a new record to the multicast
 1895                  * address list for the given interface.
 1896                  */
 1897                 if ((imo->imo_membership[i] =
 1898                     in_addmulti(&mreq.imr_multiaddr, ifp)) == NULL) {
 1899                         INP_UNLOCK(inp);
 1900                         error = ENOBUFS;
 1901                         splx(s);
 1902                         break;
 1903                 }
 1904                 ++imo->imo_num_memberships;
 1905                 INP_UNLOCK(inp);
 1906                 splx(s);
 1907                 break;
 1908 
 1909         case IP_DROP_MEMBERSHIP:
 1910                 /*
 1911                  * Drop a multicast group membership.
 1912                  * Group must be a valid IP multicast address.
 1913                  */
 1914                 error = sooptcopyin(sopt, &mreq, sizeof mreq, sizeof mreq);
 1915                 if (error)
 1916                         break;
 1917 
 1918                 if (!IN_MULTICAST(ntohl(mreq.imr_multiaddr.s_addr))) {
 1919                         error = EINVAL;
 1920                         break;
 1921                 }
 1922 
 1923                 s = splimp();
 1924                 /*
 1925                  * If an interface address was specified, get a pointer
 1926                  * to its ifnet structure.
 1927                  */
 1928                 if (mreq.imr_interface.s_addr == INADDR_ANY)
 1929                         ifp = NULL;
 1930                 else {
 1931                         ifp = ip_multicast_if(&mreq.imr_interface, NULL);
 1932                         if (ifp == NULL) {
 1933                                 error = EADDRNOTAVAIL;
 1934                                 splx(s);
 1935                                 break;
 1936                         }
 1937                 }
 1938                 /*
 1939                  * Find the membership in the membership array.
 1940                  */
 1941                 imo = ip_findmoptions(inp);
 1942                 for (i = 0; i < imo->imo_num_memberships; ++i) {
 1943                         if ((ifp == NULL ||
 1944                              imo->imo_membership[i]->inm_ifp == ifp) &&
 1945                              imo->imo_membership[i]->inm_addr.s_addr ==
 1946                              mreq.imr_multiaddr.s_addr)
 1947                                 break;
 1948                 }
 1949                 if (i == imo->imo_num_memberships) {
 1950                         INP_UNLOCK(inp);
 1951                         error = EADDRNOTAVAIL;
 1952                         splx(s);
 1953                         break;
 1954                 }
 1955                 /*
 1956                  * Give up the multicast address record to which the
 1957                  * membership points.
 1958                  */
 1959                 in_delmulti(imo->imo_membership[i]);
 1960                 /*
 1961                  * Remove the gap in the membership array.
 1962                  */
 1963                 for (++i; i < imo->imo_num_memberships; ++i)
 1964                         imo->imo_membership[i-1] = imo->imo_membership[i];
 1965                 --imo->imo_num_memberships;
 1966                 INP_UNLOCK(inp);
 1967                 splx(s);
 1968                 break;
 1969 
 1970         default:
 1971                 error = EOPNOTSUPP;
 1972                 break;
 1973         }
 1974 
 1975         return (error);
 1976 }
 1977 
 1978 /*
 1979  * Return the IP multicast options in response to user getsockopt().
 1980  */
 1981 static int
 1982 ip_getmoptions(struct inpcb *inp, struct sockopt *sopt)
 1983 {
 1984         struct ip_moptions *imo;
 1985         struct in_addr addr;
 1986         struct in_ifaddr *ia;
 1987         int error, optval;
 1988         u_char coptval;
 1989 
 1990         INP_LOCK(inp);
 1991         imo = inp->inp_moptions;
 1992 
 1993         error = 0;
 1994         switch (sopt->sopt_name) {
 1995         case IP_MULTICAST_VIF: 
 1996                 if (imo != NULL)
 1997                         optval = imo->imo_multicast_vif;
 1998                 else
 1999                         optval = -1;
 2000                 INP_UNLOCK(inp);
 2001                 error = sooptcopyout(sopt, &optval, sizeof optval);
 2002                 break;
 2003 
 2004         case IP_MULTICAST_IF:
 2005                 if (imo == NULL || imo->imo_multicast_ifp == NULL)
 2006                         addr.s_addr = INADDR_ANY;
 2007                 else if (imo->imo_multicast_addr.s_addr) {
 2008                         /* return the value user has set */
 2009                         addr = imo->imo_multicast_addr;
 2010                 } else {
 2011                         IFP_TO_IA(imo->imo_multicast_ifp, ia);
 2012                         addr.s_addr = (ia == NULL) ? INADDR_ANY
 2013                                 : IA_SIN(ia)->sin_addr.s_addr;
 2014                 }
 2015                 INP_UNLOCK(inp);
 2016                 error = sooptcopyout(sopt, &addr, sizeof addr);
 2017                 break;
 2018 
 2019         case IP_MULTICAST_TTL:
 2020                 if (imo == 0)
 2021                         optval = coptval = IP_DEFAULT_MULTICAST_TTL;
 2022                 else
 2023                         optval = coptval = imo->imo_multicast_ttl;
 2024                 INP_UNLOCK(inp);
 2025                 if (sopt->sopt_valsize == 1)
 2026                         error = sooptcopyout(sopt, &coptval, 1);
 2027                 else
 2028                         error = sooptcopyout(sopt, &optval, sizeof optval);
 2029                 break;
 2030 
 2031         case IP_MULTICAST_LOOP:
 2032                 if (imo == 0)
 2033                         optval = coptval = IP_DEFAULT_MULTICAST_LOOP;
 2034                 else
 2035                         optval = coptval = imo->imo_multicast_loop;
 2036                 INP_UNLOCK(inp);
 2037                 if (sopt->sopt_valsize == 1)
 2038                         error = sooptcopyout(sopt, &coptval, 1);
 2039                 else
 2040                         error = sooptcopyout(sopt, &optval, sizeof optval);
 2041                 break;
 2042 
 2043         default:
 2044                 INP_UNLOCK(inp);
 2045                 error = ENOPROTOOPT;
 2046                 break;
 2047         }
 2048         INP_UNLOCK_ASSERT(inp);
 2049 
 2050         return (error);
 2051 }
 2052 
 2053 /*
 2054  * Discard the IP multicast options.
 2055  */
 2056 void
 2057 ip_freemoptions(imo)
 2058         register struct ip_moptions *imo;
 2059 {
 2060         register int i;
 2061 
 2062         if (imo != NULL) {
 2063                 for (i = 0; i < imo->imo_num_memberships; ++i)
 2064                         in_delmulti(imo->imo_membership[i]);
 2065                 free(imo, M_IPMOPTS);
 2066         }
 2067 }
 2068 
 2069 /*
 2070  * Routine called from ip_output() to loop back a copy of an IP multicast
 2071  * packet to the input queue of a specified interface.  Note that this
 2072  * calls the output routine of the loopback "driver", but with an interface
 2073  * pointer that might NOT be a loopback interface -- evil, but easier than
 2074  * replicating that code here.
 2075  */
 2076 static void
 2077 ip_mloopback(ifp, m, dst, hlen)
 2078         struct ifnet *ifp;
 2079         register struct mbuf *m;
 2080         register struct sockaddr_in *dst;
 2081         int hlen;
 2082 {
 2083         register struct ip *ip;
 2084         struct mbuf *copym;
 2085 
 2086         copym = m_copy(m, 0, M_COPYALL);
 2087         if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
 2088                 copym = m_pullup(copym, hlen);
 2089         if (copym != NULL) {
 2090                 /* If needed, compute the checksum and mark it as valid. */
 2091                 if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 2092                         in_delayed_cksum(copym);
 2093                         copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 2094                         copym->m_pkthdr.csum_flags |=
 2095                             CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
 2096                         copym->m_pkthdr.csum_data = 0xffff;
 2097                 }
 2098                 /*
 2099                  * We don't bother to fragment if the IP length is greater
 2100                  * than the interface's MTU.  Can this possibly matter?
 2101                  */
 2102                 ip = mtod(copym, struct ip *);
 2103                 ip->ip_len = htons(ip->ip_len);
 2104                 ip->ip_off = htons(ip->ip_off);
 2105                 ip->ip_sum = 0;
 2106                 ip->ip_sum = in_cksum(copym, hlen);
 2107                 /*
 2108                  * NB:
 2109                  * It's not clear whether there are any lingering
 2110                  * reentrancy problems in other areas which might
 2111                  * be exposed by using ip_input directly (in
 2112                  * particular, everything which modifies the packet
 2113                  * in-place).  Yet another option is using the
 2114                  * protosw directly to deliver the looped back
 2115                  * packet.  For the moment, we'll err on the side
 2116                  * of safety by using if_simloop().
 2117                  */
 2118 #if 1 /* XXX */
 2119                 if (dst->sin_family != AF_INET) {
 2120                         printf("ip_mloopback: bad address family %d\n",
 2121                                                 dst->sin_family);
 2122                         dst->sin_family = AF_INET;
 2123                 }
 2124 #endif
 2125 
 2126 #ifdef notdef
 2127                 copym->m_pkthdr.rcvif = ifp;
 2128                 ip_input(copym);
 2129 #else
 2130                 if_simloop(ifp, copym, dst->sin_family, 0);
 2131 #endif
 2132         }
 2133 }

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