sys/netinet/ip_output.c

   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  * 3. 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: src/sys/netinet/ip_output.c,v 1.99.2.37 2003/04/15 06:44:45 silby Exp $
  31  */
  32
  33 #define _IP_VHL
  34
  35 #include "opt_ipdn.h"
  36 #include "opt_ipdivert.h"
  37 #include "opt_mbuf_stress_test.h"
  38 #include "opt_mpls.h"
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/kernel.h>
  43 #include <sys/malloc.h>
  44 #include <sys/mbuf.h>
  45 #include <sys/protosw.h>
  46 #include <sys/socket.h>
  47 #include <sys/socketvar.h>
  48 #include <sys/proc.h>
  49 #include <sys/priv.h>
  50 #include <sys/sysctl.h>
  51 #include <sys/in_cksum.h>
  52 #include <sys/lock.h>
  53
  54 #include <sys/thread2.h>
  55 #include <sys/mplock2.h>
  56 #include <sys/msgport2.h>
  57
  58 #include <net/if.h>
  59 #include <net/netisr.h>
  60 #include <net/pfil.h>
  61 #include <net/route.h>
  62
  63 #include <netinet/in.h>
  64 #include <netinet/in_systm.h>
  65 #include <netinet/ip.h>
  66 #include <netinet/in_pcb.h>
  67 #include <netinet/in_var.h>
  68 #include <netinet/ip_var.h>
  69
  70 #include <netproto/mpls/mpls_var.h>
  71
  72 static MALLOC_DEFINE(M_IPMOPTS, "ip_moptions", "internet multicast options");
  73
  74 #include <net/ipfw/ip_fw.h>
  75 #include <net/dummynet/ip_dummynet.h>
  76
  77 #define print_ip(x, a, y)        kprintf("%s %d.%d.%d.%d%s",\
  78                                 x, (ntohl(a.s_addr)>>24)&0xFF,\
  79                                   (ntohl(a.s_addr)>>16)&0xFF,\
  80                                   (ntohl(a.s_addr)>>8)&0xFF,\
  81                                   (ntohl(a.s_addr))&0xFF, y);
  82
  83 u_short ip_id;
  84
  85 #ifdef MBUF_STRESS_TEST
  86 int mbuf_frag_size = 0;
  87 SYSCTL_INT(_net_inet_ip, OID_AUTO, mbuf_frag_size, CTLFLAG_RW,
  88         &mbuf_frag_size, 0, "Fragment outgoing mbufs to this size");
  89 #endif
  90
  91 static int ip_do_rfc6864 = 1;
  92 SYSCTL_INT(_net_inet_ip, OID_AUTO, rfc6864, CTLFLAG_RW, &ip_do_rfc6864, 0,
  93     "Don't generate IP ID for DF IP datagrams");
  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
 100         (struct sockopt *, struct ip_moptions *);
 101 static int      ip_pcbopts(int, struct mbuf **, struct mbuf *);
 102 static int      ip_setmoptions
 103         (struct sockopt *, struct ip_moptions **);
 104
 105 int     ip_optcopy(struct ip *, struct ip *);
 106
 107 extern  struct protosw inetsw[];
 108
 109 static int
 110 ip_localforward(struct mbuf *m, const struct sockaddr_in *dst, int hlen)
 111 {
 112         struct in_ifaddr_container *iac;
 113
 114         /*
 115          * We need to figure out if we have been forwarded to a local
 116          * socket.  If so, then we should somehow "loop back" to
 117          * ip_input(), and get directed to the PCB as if we had received
 118          * this packet.  This is because it may be difficult to identify
 119          * the packets you want to forward until they are being output
 120          * and have selected an interface (e.g. locally initiated
 121          * packets).  If we used the loopback inteface, we would not be
 122          * able to control what happens as the packet runs through
 123          * ip_input() as it is done through a ISR.
 124          */
 125         LIST_FOREACH(iac, INADDR_HASH(dst->sin_addr.s_addr), ia_hash) {
 126                 /*
 127                  * If the addr to forward to is one of ours, we pretend
 128                  * to be the destination for this packet.
 129                  */
 130                 if (IA_SIN(iac->ia)->sin_addr.s_addr == dst->sin_addr.s_addr)
 131                         break;
 132         }
 133         if (iac != NULL) {
 134                 if (m->m_pkthdr.rcvif == NULL)
 135                         m->m_pkthdr.rcvif = loif;
 136                 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
 137                         m->m_pkthdr.csum_flags |= CSUM_DATA_VALID |
 138                                                   CSUM_PSEUDO_HDR;
 139                         m->m_pkthdr.csum_data = 0xffff;
 140                 }
 141                 m->m_pkthdr.csum_flags |= CSUM_IP_CHECKED | CSUM_IP_VALID;
 142
 143                 /*
 144                  * Make sure that the IP header is in one mbuf,
 145                  * required by ip_input
 146                  */
 147                 if (m->m_len < hlen) {
 148                         m = m_pullup(m, hlen);
 149                         if (m == NULL) {
 150                                 /* The packet was freed; we are done */
 151                                 return 1;
 152                         }
 153                 }
 154                 ip_input(m);
 155
 156                 return 1; /* The packet gets forwarded locally */
 157         }
 158         return 0;
 159 }
 160
 161 /*
 162  * IP output.  The packet in mbuf chain m contains a skeletal IP
 163  * header (with len, off, ttl, proto, tos, src, dst).
 164  * The mbuf chain containing the packet will be freed.
 165  * The mbuf opt, if present, will not be freed.
 166  */
 167 int
 168 ip_output(struct mbuf *m0, struct mbuf *opt, struct route *ro,
 169           int flags, struct ip_moptions *imo, struct inpcb *inp)
 170 {
 171         struct ip *ip;
 172         struct ifnet *ifp = NULL;       /* keep compiler happy */
 173         struct mbuf *m;
 174         int hlen = sizeof(struct ip);
 175         int len, error = 0;
 176         struct sockaddr_in *dst = NULL; /* keep compiler happy */
 177         struct in_ifaddr *ia = NULL;
 178         int isbroadcast, sw_csum;
 179         struct in_addr pkt_dst;
 180         struct route iproute;
 181         struct m_tag *mtag;
 182         struct sockaddr_in *next_hop = NULL;
 183         int src_was_INADDR_ANY = 0;     /* as the name says... */
 184
 185         ASSERT_NETISR_NCPUS(mycpuid);
 186
 187         m = m0;
 188         M_ASSERTPKTHDR(m);
 189
 190         if (ro == NULL) {
 191                 ro = &iproute;
 192                 bzero(ro, sizeof *ro);
 193         } else if (ro->ro_rt != NULL && ro->ro_rt->rt_cpuid != mycpuid) {
 194                 if (flags & IP_DEBUGROUTE) {
 195                         panic("ip_output: rt rt_cpuid %d accessed on cpu %d\n",
 196                             ro->ro_rt->rt_cpuid, mycpuid);
 197                 }
 198
 199                 /*
 200                  * XXX
 201                  * If the cached rtentry's owner CPU is not the current CPU,
 202                  * then don't touch the cached rtentry (remote free is too
 203                  * expensive in this context); just relocate the route.
 204                  */
 205                 ro = &iproute;
 206                 bzero(ro, sizeof *ro);
 207         }
 208
 209         if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) {
 210                 /* Next hop */
 211                 mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
 212                 KKASSERT(mtag != NULL);
 213                 next_hop = m_tag_data(mtag);
 214         }
 215
 216         if (m->m_pkthdr.fw_flags & DUMMYNET_MBUF_TAGGED) {
 217                 struct dn_pkt *dn_pkt;
 218
 219                 /* Extract info from dummynet tag */
 220                 mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
 221                 KKASSERT(mtag != NULL);
 222                 dn_pkt = m_tag_data(mtag);
 223
 224                 /*
 225                  * The packet was already tagged, so part of the
 226                  * processing was already done, and we need to go down.
 227                  * Get the calculated parameters from the tag.
 228                  */
 229                 ifp = dn_pkt->ifp;
 230
 231                 KKASSERT(ro == &iproute);
 232                 *ro = dn_pkt->ro; /* structure copy */
 233                 KKASSERT(ro->ro_rt == NULL || ro->ro_rt->rt_cpuid == mycpuid);
 234
 235                 dst = dn_pkt->dn_dst;
 236                 if (dst == (struct sockaddr_in *)&(dn_pkt->ro.ro_dst)) {
 237                         /* If 'dst' points into dummynet tag, adjust it */
 238                         dst = (struct sockaddr_in *)&(ro->ro_dst);
 239                 }
 240
 241                 ip = mtod(m, struct ip *);
 242                 hlen = IP_VHL_HL(ip->ip_vhl) << 2 ;
 243                 if (ro->ro_rt)
 244                         ia = ifatoia(ro->ro_rt->rt_ifa);
 245                 goto sendit;
 246         }
 247
 248         if (opt) {
 249                 len = 0;
 250                 m = ip_insertoptions(m, opt, &len);
 251                 if (len != 0)
 252                         hlen = len;
 253         }
 254         ip = mtod(m, struct ip *);
 255
 256         /*
 257          * Fill in IP header.
 258          */
 259         if (!(flags & (IP_FORWARDING|IP_RAWOUTPUT))) {
 260                 ip->ip_vhl = IP_MAKE_VHL(IPVERSION, hlen >> 2);
 261                 ip->ip_off &= htons(IP_DF);
 262                 if (ip_do_rfc6864 && (ip->ip_off & htons(IP_DF)))
 263                         ip->ip_id = 0;
 264                 else
 265                         ip->ip_id = ip_newid();
 266                 ipstat.ips_localout++;
 267         } else {
 268                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 269         }
 270
 271 reroute:
 272         pkt_dst = next_hop ? next_hop->sin_addr : ip->ip_dst;
 273
 274         dst = (struct sockaddr_in *)&ro->ro_dst;
 275         /*
 276          * If there is a cached route,
 277          * check that it is to the same destination
 278          * and is still up.  If not, free it and try again.
 279          * The address family should also be checked in case of sharing the
 280          * cache with IPv6.
 281          */
 282         if (ro->ro_rt &&
 283             (!(ro->ro_rt->rt_flags & RTF_UP) ||
 284              dst->sin_family != AF_INET ||
 285              dst->sin_addr.s_addr != pkt_dst.s_addr)) {
 286                 rtfree(ro->ro_rt);
 287                 ro->ro_rt = NULL;
 288         }
 289         if (ro->ro_rt == NULL) {
 290                 bzero(dst, sizeof *dst);
 291                 dst->sin_family = AF_INET;
 292                 dst->sin_len = sizeof *dst;
 293                 dst->sin_addr = pkt_dst;
 294         }
 295         /*
 296          * If routing to interface only,
 297          * short circuit routing lookup.
 298          */
 299         if (flags & IP_ROUTETOIF) {
 300                 if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
 301                     (ia = ifatoia(ifa_ifwithnet(sintosa(dst)))) == NULL) {
 302                         ipstat.ips_noroute++;
 303                         error = ENETUNREACH;
 304                         goto bad;
 305                 }
 306                 ifp = ia->ia_ifp;
 307                 ip->ip_ttl = 1;
 308                 isbroadcast = in_broadcast(dst->sin_addr, ifp);
 309         } else if (IN_MULTICAST(ntohl(pkt_dst.s_addr)) &&
 310                    imo != NULL && imo->imo_multicast_ifp != NULL) {
 311                 /*
 312                  * Bypass the normal routing lookup for multicast
 313                  * packets if the interface is specified.
 314                  */
 315                 ifp = imo->imo_multicast_ifp;
 316                 ia = IFP_TO_IA(ifp);
 317                 isbroadcast = 0;        /* fool gcc */
 318         } else {
 319                 /*
 320                  * If this is the case, we probably don't want to allocate
 321                  * a protocol-cloned route since we didn't get one from the
 322                  * ULP.  This lets TCP do its thing, while not burdening
 323                  * forwarding or ICMP with the overhead of cloning a route.
 324                  * Of course, we still want to do any cloning requested by
 325                  * the link layer, as this is probably required in all cases
 326                  * for correct operation (as it is for ARP).
 327                  */
 328                 if (ro->ro_rt == NULL)
 329                         rtalloc_ign(ro, RTF_PRCLONING);
 330                 if (ro->ro_rt == NULL) {
 331                         ipstat.ips_noroute++;
 332                         error = EHOSTUNREACH;
 333                         goto bad;
 334                 }
 335                 ia = ifatoia(ro->ro_rt->rt_ifa);
 336                 ifp = ro->ro_rt->rt_ifp;
 337                 ro->ro_rt->rt_use++;
 338                 if (ro->ro_rt->rt_flags & RTF_GATEWAY)
 339                         dst = (struct sockaddr_in *)ro->ro_rt->rt_gateway;
 340                 if (ro->ro_rt->rt_flags & RTF_HOST)
 341                         isbroadcast = (ro->ro_rt->rt_flags & RTF_BROADCAST);
 342                 else
 343                         isbroadcast = in_broadcast(dst->sin_addr, ifp);
 344         }
 345         if (IN_MULTICAST(ntohl(pkt_dst.s_addr))) {
 346                 m->m_flags |= M_MCAST;
 347                 /*
 348                  * IP destination address is multicast.  Make sure "dst"
 349                  * still points to the address in "ro".  (It may have been
 350                  * changed to point to a gateway address, above.)
 351                  */
 352                 dst = (struct sockaddr_in *)&ro->ro_dst;
 353                 /*
 354                  * See if the caller provided any multicast options
 355                  */
 356                 if (imo != NULL) {
 357                         ip->ip_ttl = imo->imo_multicast_ttl;
 358                         if (imo->imo_multicast_vif != -1) {
 359                                 ip->ip_src.s_addr =
 360                                     ip_mcast_src ?
 361                                     ip_mcast_src(imo->imo_multicast_vif) :
 362                                     INADDR_ANY;
 363                         }
 364                 } else {
 365                         ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
 366                 }
 367                 /*
 368                  * Confirm that the outgoing interface supports multicast.
 369                  */
 370                 if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
 371                         if (!(ifp->if_flags & IFF_MULTICAST)) {
 372                                 ipstat.ips_noroute++;
 373                                 error = ENETUNREACH;
 374                                 goto bad;
 375                         }
 376                 }
 377                 /*
 378                  * If source address not specified yet, use address of the
 379                  * outgoing interface.  In case, keep note we did that, so
 380                  * if the the firewall changes the next-hop causing the
 381                  * output interface to change, we can fix that.
 382                  */
 383                 if (ip->ip_src.s_addr == INADDR_ANY || src_was_INADDR_ANY) {
 384                         /* Interface may have no addresses. */
 385                         if (ia != NULL) {
 386                                 ip->ip_src = IA_SIN(ia)->sin_addr;
 387                                 src_was_INADDR_ANY = 1;
 388                         }
 389                 }
 390
 391                 if (ip->ip_src.s_addr != INADDR_ANY) {
 392                         struct in_multi *inm;
 393
 394                         inm = IN_LOOKUP_MULTI(&pkt_dst, ifp);
 395                         if (inm != NULL &&
 396                             (imo == NULL || imo->imo_multicast_loop)) {
 397                                 /*
 398                                  * If we belong to the destination multicast
 399                                  * group on the outgoing interface, and the
 400                                  * caller did not forbid loopback, loop back
 401                                  * a copy.
 402                                  */
 403                                 ip_mloopback(ifp, m, dst, hlen);
 404                         } else {
 405                                 /*
 406                                  * If we are acting as a multicast router,
 407                                  * perform multicast forwarding as if the
 408                                  * packet had just arrived on the interface
 409                                  * to which we are about to send.  The
 410                                  * multicast forwarding function recursively
 411                                  * calls this function, using the IP_FORWARDING
 412                                  * flag to prevent infinite recursion.
 413                                  *
 414                                  * Multicasts that are looped back by
 415                                  * ip_mloopback(), above, will be forwarded by
 416                                  * the ip_input() routine, if necessary.
 417                                  */
 418                                 if (ip_mrouter && !(flags & IP_FORWARDING)) {
 419                                         /*
 420                                          * If rsvp daemon is not running, do
 421                                          * not set ip_moptions. This ensures
 422                                          * that the packet is multicast and
 423                                          * not just sent down one link as
 424                                          * prescribed by rsvpd.
 425                                          */
 426                                         if (!rsvp_on)
 427                                                 imo = NULL;
 428                                         if (ip_mforward) {
 429                                                 get_mplock();
 430                                                 if (ip_mforward(ip, ifp,
 431                                                     m, imo) != 0) {
 432                                                         m_freem(m);
 433                                                         rel_mplock();
 434                                                         goto done;
 435                                                 }
 436                                                 rel_mplock();
 437                                         }
 438                                 }
 439                         }
 440                 }
 441
 442                 /*
 443                  * Multicasts with a time-to-live of zero may be looped-
 444                  * back, above, but must not be transmitted on a network.
 445                  * Also, multicasts addressed to the loopback interface
 446                  * are not sent -- the above call to ip_mloopback() will
 447                  * loop back a copy if this host actually belongs to the
 448                  * destination group on the loopback interface.
 449                  */
 450                 if (ip->ip_ttl == 0 || ifp->if_flags & IFF_LOOPBACK) {
 451                         m_freem(m);
 452                         goto done;
 453                 }
 454
 455                 goto sendit;
 456         } else {
 457                 m->m_flags &= ~M_MCAST;
 458         }
 459
 460         /*
 461          * If the source address is not specified yet, use the address
 462          * of the outgoing interface.  In case, keep note we did that,
 463          * so if the the firewall changes the next-hop causing the output
 464          * interface to change, we can fix that.
 465          */
 466         if (ip->ip_src.s_addr == INADDR_ANY || src_was_INADDR_ANY) {
 467                 /* Interface may have no addresses. */
 468                 if (ia != NULL) {
 469                         ip->ip_src = IA_SIN(ia)->sin_addr;
 470                         src_was_INADDR_ANY = 1;
 471                 }
 472         }
 473
 474         /*
 475          * Look for broadcast address and
 476          * verify user is allowed to send
 477          * such a packet.
 478          */
 479         if (isbroadcast) {
 480                 if (!(ifp->if_flags & IFF_BROADCAST)) {
 481                         error = EADDRNOTAVAIL;
 482                         goto bad;
 483                 }
 484                 if (!(flags & IP_ALLOWBROADCAST)) {
 485                         error = EACCES;
 486                         goto bad;
 487                 }
 488                 /* don't allow broadcast messages to be fragmented */
 489                 if (ntohs(ip->ip_len) > ifp->if_mtu) {
 490                         error = EMSGSIZE;
 491                         goto bad;
 492                 }
 493                 m->m_flags |= M_BCAST;
 494         } else {
 495                 m->m_flags &= ~M_BCAST;
 496         }
 497
 498 sendit:
 499
 500         /* We are already being fwd'd from a firewall. */
 501         if (next_hop != NULL)
 502                 goto pass;
 503
 504         /* No pfil hooks */
 505         if (!pfil_has_hooks(&inet_pfil_hook)) {
 506                 if (m->m_pkthdr.fw_flags & DUMMYNET_MBUF_TAGGED) {
 507                         /*
 508                          * Strip dummynet tags from stranded packets
 509                          */
 510                         mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
 511                         KKASSERT(mtag != NULL);
 512                         m_tag_delete(m, mtag);
 513                         m->m_pkthdr.fw_flags &= ~DUMMYNET_MBUF_TAGGED;
 514                 }
 515                 goto pass;
 516         }
 517
 518         /*
 519          * IpHack's section.
 520          * - Xlate: translate packet's addr/port (NAT).
 521          * - Firewall: deny/allow/etc.
 522          * - Wrap: fake packet's addr/port <unimpl.>
 523          * - Encapsulate: put it in another IP and send out. <unimp.>
 524          */
 525
 526         /*
 527          * Run through list of hooks for output packets.
 528          */
 529         error = pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT);
 530         if (error != 0 || m == NULL)
 531                 goto done;
 532         ip = mtod(m, struct ip *);
 533
 534         if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) {
 535                 /*
 536                  * Check dst to make sure it is directly reachable on the
 537                  * interface we previously thought it was.
 538                  * If it isn't (which may be likely in some situations) we have
 539                  * to re-route it (ie, find a route for the next-hop and the
 540                  * associated interface) and set them here. This is nested
 541                  * forwarding which in most cases is undesirable, except where
 542                  * such control is nigh impossible. So we do it here.
 543                  * And I'm babbling.
 544                  */
 545                 mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
 546                 KKASSERT(mtag != NULL);
 547                 next_hop = m_tag_data(mtag);
 548
 549                 /*
 550                  * Try local forwarding first
 551                  */
 552                 if (ip_localforward(m, next_hop, hlen))
 553                         goto done;
 554
 555                 /*
 556                  * Relocate the route based on next_hop.
 557                  * If the current route is inp's cache, keep it untouched.
 558                  */
 559                 if (ro == &iproute && ro->ro_rt != NULL) {
 560                         RTFREE(ro->ro_rt);
 561                         ro->ro_rt = NULL;
 562                 }
 563                 ro = &iproute;
 564                 bzero(ro, sizeof *ro);
 565
 566                 /*
 567                  * Forwarding to broadcast address is not allowed.
 568                  * XXX Should we follow IP_ROUTETOIF?
 569                  */
 570                 flags &= ~(IP_ALLOWBROADCAST | IP_ROUTETOIF);
 571
 572                 /* We are doing forwarding now */
 573                 flags |= IP_FORWARDING;
 574
 575                 goto reroute;
 576         }
 577
 578         if (m->m_pkthdr.fw_flags & DUMMYNET_MBUF_TAGGED) {
 579                 struct dn_pkt *dn_pkt;
 580
 581                 mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
 582                 KKASSERT(mtag != NULL);
 583                 dn_pkt = m_tag_data(mtag);
 584
 585                 /*
 586                  * Under certain cases it is not possible to recalculate
 587                  * 'ro' and 'dst', let alone 'flags', so just save them in
 588                  * dummynet tag and avoid the possible wrong reculcalation
 589                  * when we come back to ip_output() again.
 590                  *
 591                  * All other parameters have been already used and so they
 592                  * are not needed anymore.
 593                  * XXX if the ifp is deleted while a pkt is in dummynet,
 594                  * we are in trouble! (TODO use ifnet_detach_event)
 595                  *
 596                  * We need to copy *ro because for ICMP pkts (and maybe
 597                  * others) the caller passed a pointer into the stack;
 598                  * dst might also be a pointer into *ro so it needs to
 599                  * be updated.
 600                  */
 601                 dn_pkt->ro = *ro;
 602                 if (ro->ro_rt)
 603                         ro->ro_rt->rt_refcnt++;
 604                 if (dst == (struct sockaddr_in *)&ro->ro_dst) {
 605                         /* 'dst' points into 'ro' */
 606                         dst = (struct sockaddr_in *)&(dn_pkt->ro.ro_dst);
 607                 }
 608                 dn_pkt->dn_dst = dst;
 609                 dn_pkt->flags = flags;
 610
 611                 ip_dn_queue(m);
 612                 goto done;
 613         }
 614
 615         if (m->m_pkthdr.fw_flags & IPFW_MBUF_CONTINUE) {
 616                 /* ipfw was disabled/unloaded. */
 617                 m_freem(m);
 618                 goto done;
 619         }
 620 pass:
 621         /* 127/8 must not appear on wire - RFC1122. */
 622         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
 623             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
 624                 if (!(ifp->if_flags & IFF_LOOPBACK)) {
 625                         ipstat.ips_badaddr++;
 626                         error = EADDRNOTAVAIL;
 627                         goto bad;
 628                 }
 629         }
 630         if (ip->ip_src.s_addr == INADDR_ANY ||
 631             IN_MULTICAST(ntohl(ip->ip_src.s_addr))) {
 632                 ipstat.ips_badaddr++;
 633                 error = EADDRNOTAVAIL;
 634                 goto bad;
 635         }
 636
 637         if ((m->m_pkthdr.csum_flags & CSUM_TSO) == 0) {
 638                 m->m_pkthdr.csum_flags |= CSUM_IP;
 639                 sw_csum = m->m_pkthdr.csum_flags & ~ifp->if_hwassist;
 640                 if (sw_csum & CSUM_DELAY_DATA) {
 641                         in_delayed_cksum(m);
 642                         sw_csum &= ~CSUM_DELAY_DATA;
 643                 }
 644                 m->m_pkthdr.csum_flags &= ifp->if_hwassist;
 645         } else {
 646                 sw_csum = 0;
 647         }
 648         m->m_pkthdr.csum_iphlen = hlen;
 649
 650         /*
 651          * If small enough for interface, or the interface will take
 652          * care of the fragmentation or segmentation for us, can just
 653          * send directly.
 654          */
 655         if (ntohs(ip->ip_len) <= ifp->if_mtu ||
 656             ((ifp->if_hwassist & CSUM_FRAGMENT) &&
 657               !(ip->ip_off & htons(IP_DF))) ||
 658             (m->m_pkthdr.csum_flags & CSUM_TSO))
 659         {
 660                 ip->ip_sum = 0;
 661                 if (sw_csum & CSUM_DELAY_IP) {
 662                         if (ip->ip_vhl == IP_VHL_BORING)
 663                                 ip->ip_sum = in_cksum_hdr(ip);
 664                         else
 665                                 ip->ip_sum = in_cksum(m, hlen);
 666                 }
 667
 668                 /* Record statistics for this interface address. */
 669                 if (!(flags & IP_FORWARDING) && ia) {
 670                         IFA_STAT_INC(&ia->ia_ifa, opackets, 1);
 671                         IFA_STAT_INC(&ia->ia_ifa, obytes, m->m_pkthdr.len);
 672                 }
 673
 674 #ifdef MBUF_STRESS_TEST
 675                 if (mbuf_frag_size && m->m_pkthdr.len > mbuf_frag_size) {
 676                         struct mbuf *m1, *m2;
 677                         int length, tmp;
 678
 679                         tmp = length = m->m_pkthdr.len;
 680
 681                         while ((length -= mbuf_frag_size) >= 1) {
 682                                 m1 = m_split(m, length, M_NOWAIT);
 683                                 if (m1 == NULL)
 684                                         break;
 685                                 m2 = m;
 686                                 while (m2->m_next != NULL)
 687                                         m2 = m2->m_next;
 688                                 m2->m_next = m1;
 689                         }
 690                         m->m_pkthdr.len = tmp;
 691                 }
 692 #endif
 693
 694 #ifdef MPLS
 695                 if (!mpls_output_process(m, ro->ro_rt))
 696                         goto done;
 697 #endif
 698                 error = ifp->if_output(ifp, m, (struct sockaddr *)dst,
 699                                        ro->ro_rt);
 700                 goto done;
 701         }
 702
 703         if (ip->ip_off & htons(IP_DF)) {
 704                 error = EMSGSIZE;
 705                 /*
 706                  * This case can happen if the user changed the MTU
 707                  * of an interface after enabling IP on it.  Because
 708                  * most netifs don't keep track of routes pointing to
 709                  * them, there is no way for one to update all its
 710                  * routes when the MTU is changed.
 711                  */
 712                 if ((ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) &&
 713                     !(ro->ro_rt->rt_rmx.rmx_locks & RTV_MTU) &&
 714                     (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)) {
 715                         ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
 716                 }
 717                 ipstat.ips_cantfrag++;
 718                 goto bad;
 719         }
 720
 721         /*
 722          * Too large for interface; fragment if possible. If successful,
 723          * on return, m will point to a list of packets to be sent.
 724          */
 725         error = ip_fragment(ip, &m, ifp->if_mtu, ifp->if_hwassist, sw_csum);
 726         if (error)
 727                 goto bad;
 728         for (; m; m = m0) {
 729                 m0 = m->m_nextpkt;
 730                 m->m_nextpkt = NULL;
 731                 if (error == 0) {
 732                         /* Record statistics for this interface address. */
 733                         if (ia != NULL) {
 734                                 IFA_STAT_INC(&ia->ia_ifa, opackets, 1);
 735                                 IFA_STAT_INC(&ia->ia_ifa, obytes,
 736                                     m->m_pkthdr.len);
 737                         }
 738 #ifdef MPLS
 739                         if (!mpls_output_process(m, ro->ro_rt))
 740                                 continue;
 741 #endif
 742                         error = ifp->if_output(ifp, m, (struct sockaddr *)dst,
 743                                                ro->ro_rt);
 744                 } else {
 745                         m_freem(m);
 746                 }
 747         }
 748
 749         if (error == 0)
 750                 ipstat.ips_fragmented++;
 751
 752 done:
 753         if (ro == &iproute && ro->ro_rt != NULL) {
 754                 RTFREE(ro->ro_rt);
 755                 ro->ro_rt = NULL;
 756         }
 757         return (error);
 758 bad:
 759         m_freem(m);
 760         goto done;
 761 }
 762
 763 /*
 764  * Create a chain of fragments which fit the given mtu. m_frag points to the
 765  * mbuf to be fragmented; on return it points to the chain with the fragments.
 766  * Return 0 if no error. If error, m_frag may contain a partially built
 767  * chain of fragments that should be freed by the caller.
 768  *
 769  * if_hwassist_flags is the hw offload capabilities (see if_data.ifi_hwassist)
 770  * sw_csum contains the delayed checksums flags (e.g., CSUM_DELAY_IP).
 771  */
 772 int
 773 ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
 774             u_long if_hwassist_flags, int sw_csum)
 775 {
 776         int error = 0;
 777         int hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 778         int len = (mtu - hlen) & ~7;    /* size of payload in each fragment */
 779         int off;
 780         struct mbuf *m0 = *m_frag;      /* the original packet          */
 781         int firstlen;
 782         struct mbuf **mnext;
 783         int nfrags;
 784
 785         if (ip->ip_off & htons(IP_DF)) { /* Fragmentation not allowed */
 786                 ipstat.ips_cantfrag++;
 787                 return EMSGSIZE;
 788         }
 789
 790         /*
 791          * Must be able to put at least 8 bytes per fragment.
 792          */
 793         if (len < 8)
 794                 return EMSGSIZE;
 795
 796         /*
 797          * If the interface will not calculate checksums on
 798          * fragmented packets, then do it here.
 799          */
 800         if ((m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA) &&
 801             !(if_hwassist_flags & CSUM_IP_FRAGS)) {
 802                 in_delayed_cksum(m0);
 803                 m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 804         }
 805
 806         if (len > PAGE_SIZE) {
 807                 /*
 808                  * Fragment large datagrams such that each segment
 809                  * contains a multiple of PAGE_SIZE amount of data,
 810                  * plus headers. This enables a receiver to perform
 811                  * page-flipping zero-copy optimizations.
 812                  *
 813                  * XXX When does this help given that sender and receiver
 814                  * could have different page sizes, and also mtu could
 815                  * be less than the receiver's page size ?
 816                  */
 817                 int newlen;
 818                 struct mbuf *m;
 819
 820                 for (m = m0, off = 0; m && (off+m->m_len) <= mtu; m = m->m_next)
 821                         off += m->m_len;
 822
 823                 /*
 824                  * firstlen (off - hlen) must be aligned on an
 825                  * 8-byte boundary
 826                  */
 827                 if (off < hlen)
 828                         goto smart_frag_failure;
 829                 off = ((off - hlen) & ~7) + hlen;
 830                 newlen = (~PAGE_MASK) & mtu;
 831                 if ((newlen + sizeof(struct ip)) > mtu) {
 832                         /* we failed, go back the default */
 833 smart_frag_failure:
 834                         newlen = len;
 835                         off = hlen + len;
 836                 }
 837                 len = newlen;
 838
 839         } else {
 840                 off = hlen + len;
 841         }
 842
 843         firstlen = off - hlen;
 844         mnext = &m0->m_nextpkt;         /* pointer to next packet */
 845
 846         /*
 847          * Loop through length of segment after first fragment,
 848          * make new header and copy data of each part and link onto chain.
 849          * Here, m0 is the original packet, m is the fragment being created.
 850          * The fragments are linked off the m_nextpkt of the original
 851          * packet, which after processing serves as the first fragment.
 852          */
 853         for (nfrags = 1; off < ntohs(ip->ip_len); off += len, nfrags++) {
 854                 struct ip *mhip;        /* ip header on the fragment */
 855                 struct mbuf *m;
 856                 int mhlen = sizeof(struct ip);
 857
 858                 MGETHDR(m, M_NOWAIT, MT_HEADER);
 859                 if (m == NULL) {
 860                         error = ENOBUFS;
 861                         ipstat.ips_odropped++;
 862                         goto done;
 863                 }
 864                 m->m_flags |= (m0->m_flags & M_MCAST) | M_FRAG;
 865                 /*
 866                  * In the first mbuf, leave room for the link header, then
 867                  * copy the original IP header including options. The payload
 868                  * goes into an additional mbuf chain returned by m_copy().
 869                  */
 870                 m->m_data += max_linkhdr;
 871                 mhip = mtod(m, struct ip *);
 872                 *mhip = *ip;
 873                 if (hlen > sizeof(struct ip)) {
 874                         mhlen = ip_optcopy(ip, mhip) + sizeof(struct ip);
 875                         mhip->ip_vhl = IP_MAKE_VHL(IPVERSION, mhlen >> 2);
 876                 }
 877                 m->m_len = mhlen;
 878                 /* XXX do we need to add ip->ip_off below ? */
 879                 mhip->ip_off = htons(((off - hlen) >> 3) + ntohs(ip->ip_off));
 880                 if (off + len >= ntohs(ip->ip_len)) {   /* last fragment */
 881                         len = ntohs(ip->ip_len) - off;
 882                         m->m_flags |= M_LASTFRAG;
 883                 } else {
 884                         mhip->ip_off |= htons(IP_MF);
 885                 }
 886                 mhip->ip_len = htons((u_short)(len + mhlen));
 887                 m->m_next = m_copy(m0, off, len);
 888                 if (m->m_next == NULL) {                /* copy failed */
 889                         m_free(m);
 890                         error = ENOBUFS;        /* ??? */
 891                         ipstat.ips_odropped++;
 892                         goto done;
 893                 }
 894                 m->m_pkthdr.len = mhlen + len;
 895                 m->m_pkthdr.rcvif = NULL;
 896                 m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
 897                 m->m_pkthdr.csum_iphlen = mhlen;
 898                 mhip->ip_sum = 0;
 899                 if (sw_csum & CSUM_DELAY_IP)
 900                         mhip->ip_sum = in_cksum(m, mhlen);
 901                 *mnext = m;
 902                 mnext = &m->m_nextpkt;
 903         }
 904         ipstat.ips_ofragments += nfrags;
 905
 906         /* set first marker for fragment chain */
 907         m0->m_flags |= M_FIRSTFRAG | M_FRAG;
 908         m0->m_pkthdr.csum_data = nfrags;
 909
 910         /*
 911          * Update first fragment by trimming what's been copied out
 912          * and updating header.
 913          */
 914         m_adj(m0, hlen + firstlen - ntohs(ip->ip_len));
 915         m0->m_pkthdr.len = hlen + firstlen;
 916         ip->ip_len = htons((u_short)m0->m_pkthdr.len);
 917         ip->ip_off |= htons(IP_MF);
 918         ip->ip_sum = 0;
 919         if (sw_csum & CSUM_DELAY_IP)
 920                 ip->ip_sum = in_cksum(m0, hlen);
 921
 922 done:
 923         *m_frag = m0;
 924         return error;
 925 }
 926
 927 void
 928 in_delayed_cksum(struct mbuf *m)
 929 {
 930         struct ip *ip;
 931         u_short csum, offset;
 932
 933         ip = mtod(m, struct ip *);
 934         offset = IP_VHL_HL(ip->ip_vhl) << 2 ;
 935         csum = in_cksum_skip(m, ntohs(ip->ip_len), offset);
 936         if (m->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
 937                 csum = 0xffff;
 938         offset += m->m_pkthdr.csum_data;        /* checksum offset */
 939
 940         if (offset + sizeof(u_short) > m->m_len) {
 941                 kprintf("delayed m_pullup, m->len: %d  off: %d  p: %d\n",
 942                     m->m_len, offset, ip->ip_p);
 943                 /*
 944                  * XXX
 945                  * this shouldn't happen, but if it does, the
 946                  * correct behavior may be to insert the checksum
 947                  * in the existing chain instead of rearranging it.
 948                  */
 949                 m = m_pullup(m, offset + sizeof(u_short));
 950         }
 951         *(u_short *)(m->m_data + offset) = csum;
 952 }
 953
 954 /*
 955  * Insert IP options into preformed packet.
 956  * Adjust IP destination as required for IP source routing,
 957  * as indicated by a non-zero in_addr at the start of the options.
 958  *
 959  * XXX This routine assumes that the packet has no options in place.
 960  */
 961 static struct mbuf *
 962 ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen)
 963 {
 964         struct ipoption *p = mtod(opt, struct ipoption *);
 965         struct mbuf *n;
 966         struct ip *ip = mtod(m, struct ip *);
 967         unsigned optlen;
 968
 969         optlen = opt->m_len - sizeof p->ipopt_dst;
 970         if (optlen + (u_short)ntohs(ip->ip_len) > IP_MAXPACKET) {
 971                 *phlen = 0;
 972                 return (m);             /* XXX should fail */
 973         }
 974         if (p->ipopt_dst.s_addr)
 975                 ip->ip_dst = p->ipopt_dst;
 976         if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
 977                 MGETHDR(n, M_NOWAIT, MT_HEADER);
 978                 if (n == NULL) {
 979                         *phlen = 0;
 980                         return (m);
 981                 }
 982                 n->m_pkthdr.rcvif = NULL;
 983                 n->m_pkthdr.len = m->m_pkthdr.len + optlen;
 984                 m->m_len -= sizeof(struct ip);
 985                 m->m_data += sizeof(struct ip);
 986                 n->m_next = m;
 987                 m = n;
 988                 m->m_len = optlen + sizeof(struct ip);
 989                 m->m_data += max_linkhdr;
 990                 memcpy(mtod(m, void *), ip, sizeof(struct ip));
 991         } else {
 992                 m->m_data -= optlen;
 993                 m->m_len += optlen;
 994                 m->m_pkthdr.len += optlen;
 995                 bcopy(ip, mtod(m, caddr_t), sizeof(struct ip));
 996         }
 997         ip = mtod(m, struct ip *);
 998         bcopy(p->ipopt_list, ip + 1, optlen);
 999         *phlen = sizeof(struct ip) + optlen;
1000         ip->ip_vhl = IP_MAKE_VHL(IPVERSION, *phlen >> 2);
1001         ip->ip_len = htons(ntohs( ip->ip_len) + optlen);
1002         return (m);
1003 }
1004
1005 /*
1006  * Copy options from ip to jp,
1007  * omitting those not copied during fragmentation.
1008  */
1009 int
1010 ip_optcopy(struct ip *ip, struct ip *jp)
1011 {
1012         u_char *cp, *dp;
1013         int opt, optlen, cnt;
1014
1015         cp = (u_char *)(ip + 1);
1016         dp = (u_char *)(jp + 1);
1017         cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
1018         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1019                 opt = cp[0];
1020                 if (opt == IPOPT_EOL)
1021                         break;
1022                 if (opt == IPOPT_NOP) {
1023                         /* Preserve for IP mcast tunnel's LSRR alignment. */
1024                         *dp++ = IPOPT_NOP;
1025                         optlen = 1;
1026                         continue;
1027                 }
1028
1029                 KASSERT(cnt >= IPOPT_OLEN + sizeof *cp,
1030                     ("ip_optcopy: malformed ipv4 option"));
1031                 optlen = cp[IPOPT_OLEN];
1032                 KASSERT(optlen >= IPOPT_OLEN + sizeof *cp && optlen <= cnt,
1033                     ("ip_optcopy: malformed ipv4 option"));
1034
1035                 /* bogus lengths should have been caught by ip_dooptions */
1036                 if (optlen > cnt)
1037                         optlen = cnt;
1038                 if (IPOPT_COPIED(opt)) {
1039                         bcopy(cp, dp, optlen);
1040                         dp += optlen;
1041                 }
1042         }
1043         for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
1044                 *dp++ = IPOPT_EOL;
1045         return (optlen);
1046 }
1047
1048 /*
1049  * IP socket option processing.
1050  */
1051 void
1052 ip_ctloutput(netmsg_t msg)
1053 {
1054         struct socket *so = msg->base.nm_so;
1055         struct sockopt *sopt = msg->ctloutput.nm_sopt;
1056         struct  inpcb *inp = so->so_pcb;
1057         int     error, optval;
1058
1059         error = optval = 0;
1060
1061         /* Get socket's owner cpuid hint */
1062         if (sopt->sopt_level == SOL_SOCKET &&
1063             sopt->sopt_dir == SOPT_GET &&
1064             sopt->sopt_name == SO_CPUHINT) {
1065                 optval = mycpuid;
1066                 soopt_from_kbuf(sopt, &optval, sizeof(optval));
1067                 goto done;
1068         }
1069
1070         if (sopt->sopt_level != IPPROTO_IP) {
1071                 error = EINVAL;
1072                 goto done;
1073         }
1074
1075         switch (sopt->sopt_name) {
1076         case IP_MULTICAST_IF:
1077         case IP_MULTICAST_VIF:
1078         case IP_MULTICAST_TTL:
1079         case IP_MULTICAST_LOOP:
1080         case IP_ADD_MEMBERSHIP:
1081         case IP_DROP_MEMBERSHIP:
1082                 /*
1083                  * Handle multicast options in netisr0
1084                  */
1085                 if (&curthread->td_msgport != netisr_cpuport(0)) {
1086                         /* NOTE: so_port MUST NOT be checked in netisr0 */
1087                         msg->lmsg.ms_flags |= MSGF_IGNSOPORT;
1088                         lwkt_forwardmsg(netisr_cpuport(0), &msg->lmsg);
1089                         return;
1090                 }
1091                 break;
1092         }
1093
1094         switch (sopt->sopt_dir) {
1095         case SOPT_SET:
1096                 switch (sopt->sopt_name) {
1097                 case IP_OPTIONS:
1098 #ifdef notyet
1099                 case IP_RETOPTS:
1100 #endif
1101                 {
1102                         struct mbuf *m;
1103                         if (sopt->sopt_valsize > MLEN) {
1104                                 error = EMSGSIZE;
1105                                 break;
1106                         }
1107                         MGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_HEADER);
1108                         if (m == NULL) {
1109                                 error = ENOBUFS;
1110                                 break;
1111                         }
1112                         m->m_len = sopt->sopt_valsize;
1113                         error = soopt_to_kbuf(sopt, mtod(m, void *), m->m_len,
1114                                               m->m_len);
1115                         error = ip_pcbopts(sopt->sopt_name,
1116                                            &inp->inp_options, m);
1117                         goto done;
1118                 }
1119
1120                 case IP_TOS:
1121                 case IP_TTL:
1122                 case IP_MINTTL:
1123                 case IP_RECVOPTS:
1124                 case IP_RECVRETOPTS:
1125                 case IP_RECVDSTADDR:
1126                 case IP_RECVIF:
1127                 case IP_RECVTOS:
1128                 case IP_RECVTTL:
1129                         error = soopt_to_kbuf(sopt, &optval, sizeof optval,
1130                                              sizeof optval);
1131                         if (error)
1132                                 break;
1133                         switch (sopt->sopt_name) {
1134                         case IP_TOS:
1135                                 inp->inp_ip_tos = optval;
1136                                 break;
1137
1138                         case IP_TTL:
1139                                 inp->inp_ip_ttl = optval;
1140                                 break;
1141                         case IP_MINTTL:
1142                                 if (optval >= 0 && optval <= MAXTTL)
1143                                         inp->inp_ip_minttl = optval;
1144                                 else
1145                                         error = EINVAL;
1146                                 break;
1147 #define OPTSET(bit) \
1148         if (optval) \
1149                 inp->inp_flags |= bit; \
1150         else \
1151                 inp->inp_flags &= ~bit;
1152
1153                         case IP_RECVOPTS:
1154                                 OPTSET(INP_RECVOPTS);
1155                                 break;
1156
1157                         case IP_RECVRETOPTS:
1158                                 OPTSET(INP_RECVRETOPTS);
1159                                 break;
1160
1161                         case IP_RECVDSTADDR:
1162                                 OPTSET(INP_RECVDSTADDR);
1163                                 break;
1164
1165                         case IP_RECVIF:
1166                                 OPTSET(INP_RECVIF);
1167                                 break;
1168
1169                         case IP_RECVTOS:
1170                                 OPTSET(INP_RECVTOS);
1171                                 break;
1172
1173                         case IP_RECVTTL:
1174                                 OPTSET(INP_RECVTTL);
1175                                 break;
1176                         }
1177                         break;
1178 #undef OPTSET
1179
1180                 case IP_MULTICAST_IF:
1181                 case IP_MULTICAST_VIF:
1182                 case IP_MULTICAST_TTL:
1183                 case IP_MULTICAST_LOOP:
1184                 case IP_ADD_MEMBERSHIP:
1185                 case IP_DROP_MEMBERSHIP:
1186                         error = ip_setmoptions(sopt, &inp->inp_moptions);
1187                         break;
1188
1189                 case IP_PORTRANGE:
1190                         error = soopt_to_kbuf(sopt, &optval, sizeof optval,
1191                                             sizeof optval);
1192                         if (error)
1193                                 break;
1194
1195                         switch (optval) {
1196                         case IP_PORTRANGE_DEFAULT:
1197                                 inp->inp_flags &= ~(INP_LOWPORT);
1198                                 inp->inp_flags &= ~(INP_HIGHPORT);
1199                                 break;
1200
1201                         case IP_PORTRANGE_HIGH:
1202                                 inp->inp_flags &= ~(INP_LOWPORT);
1203                                 inp->inp_flags |= INP_HIGHPORT;
1204                                 break;
1205
1206                         case IP_PORTRANGE_LOW:
1207                                 inp->inp_flags &= ~(INP_HIGHPORT);
1208                                 inp->inp_flags |= INP_LOWPORT;
1209                                 break;
1210
1211                         default:
1212                                 error = EINVAL;
1213                                 break;
1214                         }
1215                         break;
1216
1217
1218                 default:
1219                         error = ENOPROTOOPT;
1220                         break;
1221                 }
1222                 break;
1223
1224         case SOPT_GET:
1225                 switch (sopt->sopt_name) {
1226                 case IP_OPTIONS:
1227                 case IP_RETOPTS:
1228                         if (inp->inp_options)
1229                                 soopt_from_kbuf(sopt, mtod(inp->inp_options,
1230                                                            char *),
1231                                                 inp->inp_options->m_len);
1232                         else
1233                                 sopt->sopt_valsize = 0;
1234                         break;
1235
1236                 case IP_TOS:
1237                 case IP_TTL:
1238                 case IP_MINTTL:
1239                 case IP_RECVOPTS:
1240                 case IP_RECVRETOPTS:
1241                 case IP_RECVDSTADDR:
1242                 case IP_RECVTOS:
1243                 case IP_RECVTTL:
1244                 case IP_RECVIF:
1245                 case IP_PORTRANGE:
1246                         switch (sopt->sopt_name) {
1247
1248                         case IP_TOS:
1249                                 optval = inp->inp_ip_tos;
1250                                 break;
1251
1252                         case IP_TTL:
1253                                 optval = inp->inp_ip_ttl;
1254                                 break;
1255                         case IP_MINTTL:
1256                                 optval = inp->inp_ip_minttl;
1257                                 break;
1258
1259 #define OPTBIT(bit)     (inp->inp_flags & bit ? 1 : 0)
1260
1261                         case IP_RECVOPTS:
1262                                 optval = OPTBIT(INP_RECVOPTS);
1263                                 break;
1264
1265                         case IP_RECVRETOPTS:
1266                                 optval = OPTBIT(INP_RECVRETOPTS);
1267                                 break;
1268
1269                         case IP_RECVDSTADDR:
1270                                 optval = OPTBIT(INP_RECVDSTADDR);
1271                                 break;
1272
1273                         case IP_RECVTOS:
1274                                 optval = OPTBIT(INP_RECVTOS);
1275                                 break;
1276
1277                         case IP_RECVTTL:
1278                                 optval = OPTBIT(INP_RECVTTL);
1279                                 break;
1280
1281                         case IP_RECVIF:
1282                                 optval = OPTBIT(INP_RECVIF);
1283                                 break;
1284
1285                         case IP_PORTRANGE:
1286                                 if (inp->inp_flags & INP_HIGHPORT)
1287                                         optval = IP_PORTRANGE_HIGH;
1288                                 else if (inp->inp_flags & INP_LOWPORT)
1289                                         optval = IP_PORTRANGE_LOW;
1290                                 else
1291                                         optval = 0;
1292                                 break;
1293                         }
1294                         soopt_from_kbuf(sopt, &optval, sizeof optval);
1295                         break;
1296
1297                 case IP_MULTICAST_IF:
1298                 case IP_MULTICAST_VIF:
1299                 case IP_MULTICAST_TTL:
1300                 case IP_MULTICAST_LOOP:
1301                 case IP_ADD_MEMBERSHIP:
1302                 case IP_DROP_MEMBERSHIP:
1303                         error = ip_getmoptions(sopt, inp->inp_moptions);
1304                         break;
1305
1306                 default:
1307                         error = ENOPROTOOPT;
1308                         break;
1309                 }
1310                 break;
1311         }
1312 done:
1313         lwkt_replymsg(&msg->lmsg, error);
1314 }
1315
1316 /*
1317  * Set up IP options in pcb for insertion in output packets.
1318  * Store in mbuf with pointer in pcbopt, adding pseudo-option
1319  * with destination address if source routed.
1320  */
1321 static int
1322 ip_pcbopts(int optname, struct mbuf **pcbopt, struct mbuf *m)
1323 {
1324         int cnt, optlen;
1325         u_char *cp;
1326         u_char opt;
1327
1328         /* turn off any old options */
1329         if (*pcbopt)
1330                 m_free(*pcbopt);
1331         *pcbopt = NULL;
1332         if (m == NULL || m->m_len == 0) {
1333                 /*
1334                  * Only turning off any previous options.
1335                  */
1336                 if (m != NULL)
1337                         m_free(m);
1338                 return (0);
1339         }
1340
1341         if (m->m_len % sizeof(int32_t))
1342                 goto bad;
1343         /*
1344          * IP first-hop destination address will be stored before
1345          * actual options; move other options back
1346          * and clear it when none present.
1347          */
1348         if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
1349                 goto bad;
1350         cnt = m->m_len;
1351         m->m_len += sizeof(struct in_addr);
1352         cp = mtod(m, u_char *) + sizeof(struct in_addr);
1353         bcopy(mtod(m, caddr_t), cp, cnt);
1354         bzero(mtod(m, caddr_t), sizeof(struct in_addr));
1355
1356         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1357                 opt = cp[IPOPT_OPTVAL];
1358                 if (opt == IPOPT_EOL)
1359                         break;
1360                 if (opt == IPOPT_NOP)
1361                         optlen = 1;
1362                 else {
1363                         if (cnt < IPOPT_OLEN + sizeof *cp)
1364                                 goto bad;
1365                         optlen = cp[IPOPT_OLEN];
1366                         if (optlen < IPOPT_OLEN + sizeof *cp || optlen > cnt)
1367                                 goto bad;
1368                 }
1369                 switch (opt) {
1370
1371                 default:
1372                         break;
1373
1374                 case IPOPT_LSRR:
1375                 case IPOPT_SSRR:
1376                         /*
1377                          * user process specifies route as:
1378                          *      ->A->B->C->D
1379                          * D must be our final destination (but we can't
1380                          * check that since we may not have connected yet).
1381                          * A is first hop destination, which doesn't appear in
1382                          * actual IP option, but is stored before the options.
1383                          */
1384                         if (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
1385                                 goto bad;
1386                         m->m_len -= sizeof(struct in_addr);
1387                         cnt -= sizeof(struct in_addr);
1388                         optlen -= sizeof(struct in_addr);
1389                         cp[IPOPT_OLEN] = optlen;
1390                         /*
1391                          * Move first hop before start of options.
1392                          */
1393                         bcopy(&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
1394                               sizeof(struct in_addr));
1395                         /*
1396                          * Then copy rest of options back
1397                          * to close up the deleted entry.
1398                          */
1399                         bcopy(&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr),
1400                               &cp[IPOPT_OFFSET+1],
1401                               cnt - (IPOPT_MINOFF - 1));
1402                         break;
1403                 }
1404         }
1405         if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
1406                 goto bad;
1407         *pcbopt = m;
1408         return (0);
1409
1410 bad:
1411         m_free(m);
1412         return (EINVAL);
1413 }
1414
1415 /*
1416  * XXX
1417  * The whole multicast option thing needs to be re-thought.
1418  * Several of these options are equally applicable to non-multicast
1419  * transmission, and one (IP_MULTICAST_TTL) totally duplicates a
1420  * standard option (IP_TTL).
1421  */
1422
1423 /*
1424  * following RFC1724 section 3.3, 0.0.0.0/8 is interpreted as interface index.
1425  */
1426 static struct ifnet *
1427 ip_multicast_if(struct in_addr *a, int *ifindexp)
1428 {
1429         int ifindex;
1430         struct ifnet *ifp;
1431
1432         if (ifindexp)
1433                 *ifindexp = 0;
1434         if (ntohl(a->s_addr) >> 24 == 0) {
1435                 ifindex = ntohl(a->s_addr) & 0xffffff;
1436                 if (ifindex < 0 || if_index < ifindex)
1437                         return NULL;
1438                 ifp = ifindex2ifnet[ifindex];
1439                 if (ifindexp)
1440                         *ifindexp = ifindex;
1441         } else {
1442                 ifp = INADDR_TO_IFP(a);
1443         }
1444         return ifp;
1445 }
1446
1447 /*
1448  * Set the IP multicast options in response to user setsockopt().
1449  */
1450 static int
1451 ip_setmoptions(struct sockopt *sopt, struct ip_moptions **imop)
1452 {
1453         int error = 0;
1454         int i;
1455         struct ip_mreqn mreqn;
1456         struct ifnet *ifp;
1457         struct ip_moptions *imo = *imop;
1458         int ifindex;
1459
1460         if (imo == NULL) {
1461                 /*
1462                  * No multicast option buffer attached to the pcb;
1463                  * allocate one and initialize to default values.
1464                  */
1465                 imo = kmalloc(sizeof *imo, M_IPMOPTS, M_WAITOK);
1466
1467                 imo->imo_multicast_ifp = NULL;
1468                 imo->imo_multicast_addr.s_addr = INADDR_ANY;
1469                 imo->imo_multicast_vif = -1;
1470                 imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
1471                 imo->imo_multicast_loop = IP_DEFAULT_MULTICAST_LOOP;
1472                 imo->imo_num_memberships = 0;
1473                 /* Assign imo to imop after all fields are setup */
1474                 cpu_sfence();
1475                 *imop = imo;
1476         }
1477         switch (sopt->sopt_name) {
1478         /* store an index number for the vif you wanna use in the send */
1479         case IP_MULTICAST_VIF:
1480                 if (legal_vif_num == 0) {
1481                         error = EOPNOTSUPP;
1482                         break;
1483                 }
1484                 error = soopt_to_kbuf(sopt, &i, sizeof i, sizeof i);
1485                 if (error)
1486                         break;
1487                 if (!legal_vif_num(i) && (i != -1)) {
1488                         error = EINVAL;
1489                         break;
1490                 }
1491                 imo->imo_multicast_vif = i;
1492                 break;
1493
1494         case IP_MULTICAST_IF:
1495                 /*
1496                  * Select the interface for outgoing multicast packets.
1497                  */
1498                 if (sopt->sopt_valsize >= sizeof(mreqn)) {
1499                         /*
1500                          * Linux compat.
1501                          */
1502                         error = soopt_to_kbuf(sopt, &mreqn,
1503                             sizeof(mreqn), sizeof(mreqn));
1504                         if (error)
1505                                 break;
1506                 } else if (sopt->sopt_valsize >= sizeof(struct ip_mreq)) {
1507                         /*
1508                          * Linux compat.
1509                          */
1510                         mreqn.imr_ifindex = 0;
1511                         error = soopt_to_kbuf(sopt, &mreqn,
1512                             sizeof(struct ip_mreq), sizeof(struct ip_mreq));
1513                         if (error)
1514                                 break;
1515                 } else {
1516                         mreqn.imr_ifindex = 0;
1517                         error = soopt_to_kbuf(sopt, &mreqn.imr_address,
1518                             sizeof(struct in_addr), sizeof(struct in_addr));
1519                         if (error)
1520                                 break;
1521                 }
1522
1523                 ifindex = mreqn.imr_ifindex;
1524                 if (ifindex != 0) {
1525                         if (ifindex < 0 || if_index < ifindex) {
1526                                 error = EINVAL;
1527                                 break;
1528                         }
1529                         ifp = ifindex2ifnet[ifindex];
1530                         mreqn.imr_address.s_addr = htonl(ifindex & 0xffffff);
1531                 } else {
1532                         /*
1533                          * INADDR_ANY is used to remove a previous selection.
1534                          * When no interface is selected, a default one is
1535                          * chosen every time a multicast packet is sent.
1536                          */
1537                         if (mreqn.imr_address.s_addr == INADDR_ANY) {
1538                                 imo->imo_multicast_ifp = NULL;
1539                                 break;
1540                         }
1541                         /*
1542                          * The selected interface is identified by its local
1543                          * IP address.  Find the interface and confirm that
1544                          * it supports multicasting.
1545                          */
1546                         ifp = ip_multicast_if(&mreqn.imr_address, &ifindex);
1547                 }
1548
1549                 if (ifp == NULL || !(ifp->if_flags & IFF_MULTICAST)) {
1550                         error = EADDRNOTAVAIL;
1551                         break;
1552                 }
1553                 imo->imo_multicast_ifp = ifp;
1554                 if (ifindex)
1555                         imo->imo_multicast_addr = mreqn.imr_address;
1556                 else
1557                         imo->imo_multicast_addr.s_addr = INADDR_ANY;
1558                 break;
1559
1560         case IP_MULTICAST_TTL:
1561                 /*
1562                  * Set the IP time-to-live for outgoing multicast packets.
1563                  * The original multicast API required a char argument,
1564                  * which is inconsistent with the rest of the socket API.
1565                  * We allow either a char or an int.
1566                  */
1567                 if (sopt->sopt_valsize == 1) {
1568                         u_char ttl;
1569                         error = soopt_to_kbuf(sopt, &ttl, 1, 1);
1570                         if (error)
1571                                 break;
1572                         imo->imo_multicast_ttl = ttl;
1573                 } else {
1574                         u_int ttl;
1575                         error = soopt_to_kbuf(sopt, &ttl, sizeof ttl, sizeof ttl);
1576                         if (error)
1577                                 break;
1578                         if (ttl > 255)
1579                                 error = EINVAL;
1580                         else
1581                                 imo->imo_multicast_ttl = ttl;
1582                 }
1583                 break;
1584
1585         case IP_MULTICAST_LOOP:
1586                 /*
1587                  * Set the loopback flag for outgoing multicast packets.
1588                  * Must be zero or one.  The original multicast API required a
1589                  * char argument, which is inconsistent with the rest
1590                  * of the socket API.  We allow either a char or an int.
1591                  */
1592                 if (sopt->sopt_valsize == 1) {
1593                         u_char loop;
1594
1595                         error = soopt_to_kbuf(sopt, &loop, 1, 1);
1596                         if (error)
1597                                 break;
1598                         imo->imo_multicast_loop = !!loop;
1599                 } else {
1600                         u_int loop;
1601
1602                         error = soopt_to_kbuf(sopt, &loop, sizeof loop,
1603                                             sizeof loop);
1604                         if (error)
1605                                 break;
1606                         imo->imo_multicast_loop = !!loop;
1607                 }
1608                 break;
1609
1610         case IP_ADD_MEMBERSHIP:
1611                 /*
1612                  * Add a multicast group membership.
1613                  * Group must be a valid IP multicast address.
1614                  */
1615                 if (sopt->sopt_valsize >= sizeof(mreqn)) {
1616                         error = soopt_to_kbuf(sopt, &mreqn,
1617                             sizeof(mreqn), sizeof(mreqn));
1618                         if (error)
1619                                 break;
1620                 } else {
1621                         mreqn.imr_ifindex = 0;
1622                         error = soopt_to_kbuf(sopt, &mreqn,
1623                             sizeof(struct ip_mreq), sizeof(struct ip_mreq));
1624                         if (error)
1625                                 break;
1626                 }
1627
1628                 if (!IN_MULTICAST(ntohl(mreqn.imr_multiaddr.s_addr))) {
1629                         error = EINVAL;
1630                         break;
1631                 }
1632
1633                 ifindex = mreqn.imr_ifindex;
1634                 if (ifindex != 0) {
1635                         if (ifindex < 0 || if_index < ifindex) {
1636                                 error = EINVAL;
1637                                 break;
1638                         }
1639                         ifp = ifindex2ifnet[ifindex];
1640                 } else if (mreqn.imr_address.s_addr == INADDR_ANY) {
1641                         struct sockaddr_in dst;
1642                         struct rtentry *rt;
1643
1644                         /*
1645                          * If no interface address or index was provided,
1646                          * use the interface of the route to the given
1647                          * multicast address.
1648                          */
1649                         bzero(&dst, sizeof(struct sockaddr_in));
1650                         dst.sin_len = sizeof(struct sockaddr_in);
1651                         dst.sin_family = AF_INET;
1652                         dst.sin_addr = mreqn.imr_multiaddr;
1653                         rt = rtlookup((struct sockaddr *)&dst);
1654                         if (rt == NULL) {
1655                                 error = EADDRNOTAVAIL;
1656                                 break;
1657                         }
1658                         --rt->rt_refcnt;
1659                         ifp = rt->rt_ifp;
1660                 } else {
1661                         ifp = ip_multicast_if(&mreqn.imr_address, NULL);
1662                 }
1663
1664                 /*
1665                  * See if we found an interface, and confirm that it
1666                  * supports multicast.
1667                  */
1668                 if (ifp == NULL || !(ifp->if_flags & IFF_MULTICAST)) {
1669                         error = EADDRNOTAVAIL;
1670                         break;
1671                 }
1672                 /*
1673                  * See if the membership already exists or if all the
1674                  * membership slots are full.
1675                  */
1676                 for (i = 0; i < imo->imo_num_memberships; ++i) {
1677                         if (imo->imo_membership[i]->inm_ifp == ifp &&
1678                             imo->imo_membership[i]->inm_addr.s_addr
1679                                                 == mreqn.imr_multiaddr.s_addr)
1680                                 break;
1681                 }
1682                 if (i < imo->imo_num_memberships) {
1683                         error = EADDRINUSE;
1684                         break;
1685                 }
1686                 if (i == IP_MAX_MEMBERSHIPS) {
1687                         error = ETOOMANYREFS;
1688                         break;
1689                 }
1690                 /*
1691                  * Everything looks good; add a new record to the multicast
1692                  * address list for the given interface.
1693                  */
1694                 if ((imo->imo_membership[i] =
1695                      in_addmulti(&mreqn.imr_multiaddr, ifp)) == NULL) {
1696                         error = ENOBUFS;
1697                         break;
1698                 }
1699                 ++imo->imo_num_memberships;
1700                 break;
1701
1702         case IP_DROP_MEMBERSHIP:
1703                 /*
1704                  * Drop a multicast group membership.
1705                  * Group must be a valid IP multicast address.
1706                  */
1707                 if (sopt->sopt_valsize >= sizeof(mreqn)) {
1708                         error = soopt_to_kbuf(sopt, &mreqn,
1709                             sizeof(mreqn), sizeof(mreqn));
1710                         if (error)
1711                                 break;
1712                 } else {
1713                         mreqn.imr_ifindex = 0;
1714                         error = soopt_to_kbuf(sopt, &mreqn,
1715                             sizeof(struct ip_mreq), sizeof(struct ip_mreq));
1716                         if (error)
1717                                 break;
1718                 }
1719
1720                 if (!IN_MULTICAST(ntohl(mreqn.imr_multiaddr.s_addr))) {
1721                         error = EINVAL;
1722                         break;
1723                 }
1724
1725                 /*
1726                  * If an interface index or address was specified, get a
1727                  * pointer to its ifnet structure.
1728                  */
1729                 ifindex = mreqn.imr_ifindex;
1730                 if (ifindex != 0) {
1731                         if (ifindex < 0 || if_index < ifindex) {
1732                                 error = EINVAL;
1733                                 break;
1734                         }
1735                         ifp = ifindex2ifnet[ifindex];
1736                 } else if (mreqn.imr_address.s_addr == INADDR_ANY) {
1737                         ifp = NULL;
1738                 } else {
1739                         ifp = ip_multicast_if(&mreqn.imr_address, NULL);
1740                         if (ifp == NULL) {
1741                                 error = EADDRNOTAVAIL;
1742                                 break;
1743                         }
1744                 }
1745                 /*
1746                  * Find the membership in the membership array.
1747                  */
1748                 for (i = 0; i < imo->imo_num_memberships; ++i) {
1749                         if ((ifp == NULL ||
1750                              imo->imo_membership[i]->inm_ifp == ifp) &&
1751                             imo->imo_membership[i]->inm_addr.s_addr ==
1752                             mreqn.imr_multiaddr.s_addr)
1753                                 break;
1754                 }
1755                 if (i == imo->imo_num_memberships) {
1756                         error = EADDRNOTAVAIL;
1757                         break;
1758                 }
1759                 /*
1760                  * Give up the multicast address record to which the
1761                  * membership points.
1762                  */
1763                 in_delmulti(imo->imo_membership[i]);
1764                 /*
1765                  * Remove the gap in the membership array.
1766                  */
1767                 for (++i; i < imo->imo_num_memberships; ++i)
1768                         imo->imo_membership[i-1] = imo->imo_membership[i];
1769                 --imo->imo_num_memberships;
1770                 break;
1771
1772         default:
1773                 error = EOPNOTSUPP;
1774                 break;
1775         }
1776
1777         return (error);
1778 }
1779
1780 /*
1781  * Return the IP multicast options in response to user getsockopt().
1782  */
1783 static int
1784 ip_getmoptions(struct sockopt *sopt, struct ip_moptions *imo)
1785 {
1786         struct in_addr addr;
1787         struct in_ifaddr *ia;
1788         int error, optval;
1789         u_char coptval;
1790
1791         error = 0;
1792         switch (sopt->sopt_name) {
1793         case IP_MULTICAST_VIF:
1794                 if (imo != NULL)
1795                         optval = imo->imo_multicast_vif;
1796                 else
1797                         optval = -1;
1798                 soopt_from_kbuf(sopt, &optval, sizeof optval);
1799                 break;
1800
1801         case IP_MULTICAST_IF:
1802                 if (imo == NULL || imo->imo_multicast_ifp == NULL)
1803                         addr.s_addr = INADDR_ANY;
1804                 else if (imo->imo_multicast_addr.s_addr) {
1805                         /* return the value user has set */
1806                         addr = imo->imo_multicast_addr;
1807                 } else {
1808                         ia = IFP_TO_IA(imo->imo_multicast_ifp);
1809                         addr.s_addr = (ia == NULL) ? INADDR_ANY
1810                                 : IA_SIN(ia)->sin_addr.s_addr;
1811                 }
1812                 soopt_from_kbuf(sopt, &addr, sizeof addr);
1813                 break;
1814
1815         case IP_MULTICAST_TTL:
1816                 if (imo == NULL)
1817                         optval = coptval = IP_DEFAULT_MULTICAST_TTL;
1818                 else
1819                         optval = coptval = imo->imo_multicast_ttl;
1820                 if (sopt->sopt_valsize == 1)
1821                         soopt_from_kbuf(sopt, &coptval, 1);
1822                 else
1823                         soopt_from_kbuf(sopt, &optval, sizeof optval);
1824                 break;
1825
1826         case IP_MULTICAST_LOOP:
1827                 if (imo == NULL)
1828                         optval = coptval = IP_DEFAULT_MULTICAST_LOOP;
1829                 else
1830                         optval = coptval = imo->imo_multicast_loop;
1831                 if (sopt->sopt_valsize == 1)
1832                         soopt_from_kbuf(sopt, &coptval, 1);
1833                 else
1834                         soopt_from_kbuf(sopt, &optval, sizeof optval);
1835                 break;
1836
1837         default:
1838                 error = ENOPROTOOPT;
1839                 break;
1840         }
1841         return (error);
1842 }
1843
1844 /*
1845  * Discard the IP multicast options.
1846  */
1847 void
1848 ip_freemoptions(struct ip_moptions *imo)
1849 {
1850         int i;
1851
1852         if (imo != NULL) {
1853                 for (i = 0; i < imo->imo_num_memberships; ++i)
1854                         in_delmulti(imo->imo_membership[i]);
1855                 kfree(imo, M_IPMOPTS);
1856         }
1857 }
1858
1859 /*
1860  * Routine called from ip_output() to loop back a copy of an IP multicast
1861  * packet to the input queue of a specified interface.  Note that this
1862  * calls the output routine of the loopback "driver", but with an interface
1863  * pointer that might NOT be a loopback interface -- evil, but easier than
1864  * replicating that code here.
1865  */
1866 static void
1867 ip_mloopback(struct ifnet *ifp, struct mbuf *m, struct sockaddr_in *dst,
1868              int hlen)
1869 {
1870         struct ip *ip;
1871         struct mbuf *copym;
1872
1873         copym = m_copypacket(m, M_NOWAIT);
1874         if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
1875                 copym = m_pullup(copym, hlen);
1876         if (copym != NULL) {
1877                 /*
1878                  * if the checksum hasn't been computed, mark it as valid
1879                  */
1880                 if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
1881                         in_delayed_cksum(copym);
1882                         copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
1883                         copym->m_pkthdr.csum_flags |=
1884                             CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
1885                         copym->m_pkthdr.csum_data = 0xffff;
1886                 }
1887                 /*
1888                  * We don't bother to fragment if the IP length is greater
1889                  * than the interface's MTU.  Can this possibly matter?
1890                  */
1891                 ip = mtod(copym, struct ip *);
1892                 ip->ip_sum = 0;
1893                 if (ip->ip_vhl == IP_VHL_BORING) {
1894                         ip->ip_sum = in_cksum_hdr(ip);
1895                 } else {
1896                         ip->ip_sum = in_cksum(copym, hlen);
1897                 }
1898                 /*
1899                  * NB:
1900                  * It's not clear whether there are any lingering
1901                  * reentrancy problems in other areas which might
1902                  * be exposed by using ip_input directly (in
1903                  * particular, everything which modifies the packet
1904                  * in-place).  Yet another option is using the
1905                  * protosw directly to deliver the looped back
1906                  * packet.  For the moment, we'll err on the side
1907                  * of safety by using if_simloop().
1908                  */
1909 #if 1 /* XXX */
1910                 if (dst->sin_family != AF_INET) {
1911                         kprintf("ip_mloopback: bad address family %d\n",
1912                                                 dst->sin_family);
1913                         dst->sin_family = AF_INET;
1914                 }
1915 #endif
1916                 if_simloop(ifp, copym, dst->sin_family, 0);
1917         }
1918 }