bsd/netinet6/udp6_output.c

   1 /*
   2  * Copyright (c) 2000-2018 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29
  30 /*      $FreeBSD: src/sys/netinet6/udp6_output.c,v 1.1.2.3 2001/08/31 13:49:58 jlemon Exp $     */
  31 /*      $KAME: udp6_output.c,v 1.31 2001/05/21 16:39:15 jinmei Exp $    */
  32
  33 /*
  34  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
  35  * All rights reserved.
  36  *
  37  * Redistribution and use in source and binary forms, with or without
  38  * modification, are permitted provided that the following conditions
  39  * are met:
  40  * 1. Redistributions of source code must retain the above copyright
  41  *    notice, this list of conditions and the following disclaimer.
  42  * 2. Redistributions in binary form must reproduce the above copyright
  43  *    notice, this list of conditions and the following disclaimer in the
  44  *    documentation and/or other materials provided with the distribution.
  45  * 3. Neither the name of the project nor the names of its contributors
  46  *    may be used to endorse or promote products derived from this software
  47  *    without specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  */
  61
  62 /*
  63  * Copyright (c) 1982, 1986, 1989, 1993
  64  *      The Regents of the University of California.  All rights reserved.
  65  *
  66  * Redistribution and use in source and binary forms, with or without
  67  * modification, are permitted provided that the following conditions
  68  * are met:
  69  * 1. Redistributions of source code must retain the above copyright
  70  *    notice, this list of conditions and the following disclaimer.
  71  * 2. Redistributions in binary form must reproduce the above copyright
  72  *    notice, this list of conditions and the following disclaimer in the
  73  *    documentation and/or other materials provided with the distribution.
  74  * 3. All advertising materials mentioning features or use of this software
  75  *    must display the following acknowledgement:
  76  *      This product includes software developed by the University of
  77  *      California, Berkeley and its contributors.
  78  * 4. Neither the name of the University nor the names of its contributors
  79  *    may be used to endorse or promote products derived from this software
  80  *    without specific prior written permission.
  81  *
  82  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  83  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  84  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  85  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  86  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  87  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  88  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  89  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  90  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  91  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  92  * SUCH DAMAGE.
  93  *
  94  *      @(#)udp_var.h   8.1 (Berkeley) 6/10/93
  95  */
  96
  97 #include <sys/param.h>
  98 #include <sys/malloc.h>
  99 #include <sys/mbuf.h>
 100 #include <sys/protosw.h>
 101 #include <sys/socket.h>
 102 #include <sys/socketvar.h>
 103 #include <sys/sysctl.h>
 104 #include <sys/errno.h>
 105 #include <sys/stat.h>
 106 #include <sys/systm.h>
 107 #include <sys/proc.h>
 108 #include <sys/syslog.h>
 109
 110 #include <machine/endian.h>
 111
 112 #include <net/if.h>
 113 #include <net/route.h>
 114 #include <net/if_types.h>
 115 #include <net/ntstat.h>
 116
 117 #include <netinet/in.h>
 118 #include <netinet/in_var.h>
 119 #include <netinet/in_systm.h>
 120 #include <netinet/in_tclass.h>
 121 #include <netinet/ip.h>
 122 #include <netinet/ip_var.h>
 123 #include <netinet/in_pcb.h>
 124 #include <netinet/udp.h>
 125 #include <netinet/udp_var.h>
 126 #include <netinet/ip6.h>
 127 #include <netinet6/ip6_var.h>
 128 #include <netinet6/in6_pcb.h>
 129 #include <netinet6/udp6_var.h>
 130 #include <netinet/icmp6.h>
 131 #include <netinet6/ip6protosw.h>
 132
 133 #if NECP
 134 #include <net/necp.h>
 135 #endif /* NECP */
 136
 137 #include <net/net_osdep.h>
 138
 139 /*
 140  * UDP protocol inplementation.
 141  * Per RFC 768, August, 1980.
 142  */
 143 extern int soreserveheadroom;
 144
 145 int
 146 udp6_output(struct in6pcb *in6p, struct mbuf *m, struct sockaddr *addr6,
 147     struct mbuf *control, struct proc *p)
 148 {
 149         u_int32_t ulen = m->m_pkthdr.len;
 150         u_int32_t plen = sizeof (struct udphdr) + ulen;
 151         struct ip6_hdr *ip6;
 152         struct udphdr *udp6;
 153         struct in6_addr *laddr, *faddr;
 154         u_short fport;
 155         int error = 0;
 156         struct ip6_pktopts opt, *optp = NULL;
 157         struct ip6_moptions *im6o;
 158         int af = AF_INET6, hlen = sizeof (struct ip6_hdr);
 159         int flags;
 160         struct sockaddr_in6 tmp;
 161         struct  in6_addr storage;
 162         int sotc = SO_TC_UNSPEC;
 163         int netsvctype = _NET_SERVICE_TYPE_UNSPEC;
 164         struct ip6_out_args ip6oa;
 165         struct flowadv *adv = &ip6oa.ip6oa_flowadv;
 166         struct socket *so = in6p->in6p_socket;
 167         struct route_in6 ro;
 168         int flowadv = 0;
 169
 170         bzero(&ip6oa, sizeof(ip6oa));
 171         ip6oa.ip6oa_boundif = IFSCOPE_NONE;
 172         ip6oa.ip6oa_flags = IP6OAF_SELECT_SRCIF;
 173
 174         /* Enable flow advisory only when connected */
 175         flowadv = (so->so_state & SS_ISCONNECTED) ? 1 : 0;
 176
 177         if (flowadv && INP_WAIT_FOR_IF_FEEDBACK(in6p)) {
 178                 error = ENOBUFS;
 179                 goto release;
 180         }
 181
 182         if (in6p->inp_flags & INP_BOUND_IF) {
 183                 ip6oa.ip6oa_boundif = in6p->inp_boundifp->if_index;
 184                 ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF;
 185         }
 186         if (INP_NO_CELLULAR(in6p))
 187                 ip6oa.ip6oa_flags |= IP6OAF_NO_CELLULAR;
 188         if (INP_NO_EXPENSIVE(in6p))
 189                 ip6oa.ip6oa_flags |= IP6OAF_NO_EXPENSIVE;
 190         if (INP_AWDL_UNRESTRICTED(in6p))
 191                 ip6oa.ip6oa_flags |= IP6OAF_AWDL_UNRESTRICTED;
 192         if (INP_INTCOPROC_ALLOWED(in6p))
 193                 ip6oa.ip6oa_flags |= IP6OAF_INTCOPROC_ALLOWED;
 194
 195         if (control) {
 196                 sotc = so_tc_from_control(control, &netsvctype);
 197                 if ((error = ip6_setpktopts(control, &opt,
 198                     NULL, IPPROTO_UDP)) != 0)
 199                         goto release;
 200                 optp = &opt;
 201         } else
 202                 optp = in6p->in6p_outputopts;
 203
 204         if (sotc == SO_TC_UNSPEC) {
 205                 sotc = so->so_traffic_class;
 206                 netsvctype = so->so_netsvctype;
 207         }
 208         ip6oa.ip6oa_sotc = sotc;
 209         ip6oa.ip6oa_netsvctype = netsvctype;
 210
 211         if (addr6) {
 212                 /*
 213                  * IPv4 version of udp_output calls in_pcbconnect in this case,
 214                  * which has its costs.
 215                  *
 216                  * Since we saw no essential reason for calling in_pcbconnect,
 217                  * we get rid of such kind of logic, and call in6_selectsrc
 218                  * and in6_pcbsetport in order to fill in the local address
 219                  * and the local port.
 220                  */
 221                 struct sockaddr_in6 *sin6 =
 222                     (struct sockaddr_in6 *)(void *)addr6;
 223
 224                 if (sin6->sin6_port == 0) {
 225                         error = EADDRNOTAVAIL;
 226                         goto release;
 227                 }
 228
 229                 if (!IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_faddr)) {
 230                         /* how about ::ffff:0.0.0.0 case? */
 231                         error = EISCONN;
 232                         goto release;
 233                 }
 234
 235                 /* protect *sin6 from overwrites */
 236                 tmp = *sin6;
 237                 sin6 = &tmp;
 238
 239                 faddr = &sin6->sin6_addr;
 240                 fport = sin6->sin6_port; /* allow 0 port */
 241
 242                 if (IN6_IS_ADDR_V4MAPPED(faddr)) {
 243                         if ((in6p->in6p_flags & IN6P_IPV6_V6ONLY)) {
 244                                 /*
 245                                  * I believe we should explicitly discard the
 246                                  * packet when mapped addresses are disabled,
 247                                  * rather than send the packet as an IPv6 one.
 248                                  * If we chose the latter approach, the packet
 249                                  * might be sent out on the wire based on the
 250                                  * default route, the situation which we'd
 251                                  * probably want to avoid.
 252                                  * (20010421 jinmei@kame.net)
 253                                  */
 254                                 error = EINVAL;
 255                                 goto release;
 256                         } else {
 257                                 af = AF_INET;
 258                         }
 259                 }
 260
 261                 /* KAME hack: embed scopeid */
 262                 if (in6_embedscope(&sin6->sin6_addr, sin6, in6p, NULL,
 263                     optp) != 0) {
 264                         error = EINVAL;
 265                         goto release;
 266                 }
 267
 268                 if (!IN6_IS_ADDR_V4MAPPED(faddr)) {
 269                         laddr = in6_selectsrc(sin6, optp,
 270                             in6p, &in6p->in6p_route, NULL, &storage,
 271                             ip6oa.ip6oa_boundif, &error);
 272                 } else
 273                         laddr = &in6p->in6p_laddr;      /* XXX */
 274                 if (laddr == NULL) {
 275                         if (error == 0)
 276                                 error = EADDRNOTAVAIL;
 277                         goto release;
 278                 }
 279                 if (in6p->in6p_lport == 0 &&
 280                     (error = in6_pcbsetport(laddr, in6p, p, 0)) != 0)
 281                         goto release;
 282         } else {
 283                 if (IN6_IS_ADDR_UNSPECIFIED(&in6p->in6p_faddr)) {
 284                         error = ENOTCONN;
 285                         goto release;
 286                 }
 287                 if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) {
 288                         if ((in6p->in6p_flags & IN6P_IPV6_V6ONLY)) {
 289                                 /*
 290                                  * XXX: this case would happen when the
 291                                  * application sets the V6ONLY flag after
 292                                  * connecting the foreign address.
 293                                  * Such applications should be fixed,
 294                                  * so we bark here.
 295                                  */
 296                                 log(LOG_INFO, "udp6_output: IPV6_V6ONLY "
 297                                     "option was set for a connected socket\n");
 298                                 error = EINVAL;
 299                                 goto release;
 300                         } else
 301                                 af = AF_INET;
 302                 }
 303                 laddr = &in6p->in6p_laddr;
 304                 faddr = &in6p->in6p_faddr;
 305                 fport = in6p->in6p_fport;
 306         }
 307
 308         if (in6p->inp_flowhash == 0)
 309                 in6p->inp_flowhash = inp_calc_flowhash(in6p);
 310         /* update flowinfo - RFC 6437 */
 311         if (in6p->inp_flow == 0 && in6p->in6p_flags & IN6P_AUTOFLOWLABEL) {
 312                 in6p->inp_flow &= ~IPV6_FLOWLABEL_MASK;
 313                 in6p->inp_flow |=
 314                     (htonl(in6p->inp_flowhash) & IPV6_FLOWLABEL_MASK);
 315         }
 316
 317         if (af == AF_INET)
 318                 hlen = sizeof (struct ip);
 319
 320         if (fport == htons(53) && !(so->so_flags1 & SOF1_DNS_COUNTED)) {
 321                 so->so_flags1 |= SOF1_DNS_COUNTED;
 322                 INC_ATOMIC_INT64_LIM(net_api_stats.nas_socket_inet_dgram_dns);
 323         }
 324
 325         /*
 326          * Calculate data length and get a mbuf
 327          * for UDP and IP6 headers.
 328          */
 329         M_PREPEND(m, hlen + sizeof (struct udphdr), M_DONTWAIT, 1);
 330         if (m == 0) {
 331                 error = ENOBUFS;
 332                 goto release;
 333         }
 334
 335         /*
 336          * Stuff checksum and output datagram.
 337          */
 338         udp6 = (struct udphdr *)(void *)(mtod(m, caddr_t) + hlen);
 339         udp6->uh_sport = in6p->in6p_lport; /* lport is always set in the PCB */
 340         udp6->uh_dport = fport;
 341         if (plen <= 0xffff)
 342                 udp6->uh_ulen = htons((u_short)plen);
 343         else
 344                 udp6->uh_ulen = 0;
 345         udp6->uh_sum = 0;
 346
 347         switch (af) {
 348         case AF_INET6:
 349                 ip6 = mtod(m, struct ip6_hdr *);
 350                 ip6->ip6_flow   = in6p->inp_flow & IPV6_FLOWINFO_MASK;
 351                 ip6->ip6_vfc    &= ~IPV6_VERSION_MASK;
 352                 ip6->ip6_vfc    |= IPV6_VERSION;
 353 #if 0           /* ip6_plen will be filled in ip6_output. */
 354                 ip6->ip6_plen   = htons((u_short)plen);
 355 #endif
 356                 ip6->ip6_nxt    = IPPROTO_UDP;
 357                 ip6->ip6_hlim   = in6_selecthlim(in6p, in6p->in6p_route.ro_rt ?
 358                     in6p->in6p_route.ro_rt->rt_ifp : NULL);
 359                 ip6->ip6_src    = *laddr;
 360                 ip6->ip6_dst    = *faddr;
 361
 362                 udp6->uh_sum = in6_pseudo(laddr, faddr,
 363                     htonl(plen + IPPROTO_UDP));
 364                 m->m_pkthdr.csum_flags = (CSUM_UDPIPV6|CSUM_ZERO_INVERT);
 365                 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
 366
 367                 if (!IN6_IS_ADDR_UNSPECIFIED(laddr))
 368                         ip6oa.ip6oa_flags |= IP6OAF_BOUND_SRCADDR;
 369
 370                 flags = IPV6_OUTARGS;
 371
 372                 udp6stat.udp6s_opackets++;
 373
 374 #if NECP
 375                 {
 376                         necp_kernel_policy_id policy_id;
 377                         u_int32_t route_rule_id;
 378
 379                         /*
 380                          * We need a route to perform NECP route rule checks
 381                          */
 382                         if (net_qos_policy_restricted != 0 &&
 383                             ROUTE_UNUSABLE(&in6p->inp_route)) {
 384                                 struct sockaddr_in6 to;
 385                                 struct sockaddr_in6 from;
 386
 387                                 ROUTE_RELEASE(&in6p->inp_route);
 388
 389                                 bzero(&from, sizeof(struct sockaddr_in6));
 390                                 from.sin6_family = AF_INET6;
 391                                 from.sin6_len = sizeof(struct sockaddr_in6);
 392                                 from.sin6_addr = *laddr;
 393
 394                                 bzero(&to, sizeof(struct sockaddr_in6));
 395                                 to.sin6_family = AF_INET6;
 396                                 to.sin6_len = sizeof(struct sockaddr_in6);
 397                                 to.sin6_addr = *faddr;
 398
 399                                 in6p->inp_route.ro_dst.sa_family = AF_INET6;
 400                                 in6p->inp_route.ro_dst.sa_len = sizeof(struct sockaddr_in6);
 401                                 ((struct sockaddr_in6 *)(void *)&in6p->inp_route.ro_dst)->sin6_addr =
 402                                         *faddr;
 403
 404                                 rtalloc_scoped(&in6p->inp_route, ip6oa.ip6oa_boundif);
 405
 406                                 inp_update_necp_policy(in6p, (struct sockaddr *)&from,
 407                                     (struct sockaddr *)&to, ip6oa.ip6oa_boundif);
 408                                 in6p->inp_policyresult.results.qos_marking_gencount = 0;
 409                         }
 410
 411                         if (!necp_socket_is_allowed_to_send_recv_v6(in6p, in6p->in6p_lport, fport, laddr, faddr, NULL, &policy_id, &route_rule_id)) {
 412                                 error = EHOSTUNREACH;
 413                                 goto release;
 414                         }
 415
 416                         necp_mark_packet_from_socket(m, in6p, policy_id, route_rule_id);
 417
 418                         if (net_qos_policy_restricted != 0) {
 419                                 necp_socket_update_qos_marking(in6p, in6p->in6p_route.ro_rt,
 420                                     NULL, route_rule_id);
 421                         }
 422                 }
 423 #endif /* NECP */
 424                 if ((so->so_flags1 & SOF1_QOSMARKING_ALLOWED))
 425                         ip6oa.ip6oa_flags |= IP6OAF_QOSMARKING_ALLOWED;
 426
 427 #if IPSEC
 428                 if (in6p->in6p_sp != NULL && ipsec_setsocket(m, so) != 0) {
 429                         error = ENOBUFS;
 430                         goto release;
 431                 }
 432 #endif /*IPSEC*/
 433
 434                 /* In case of IPv4-mapped address used in previous send */
 435                 if (ROUTE_UNUSABLE(&in6p->in6p_route) ||
 436                     rt_key(in6p->in6p_route.ro_rt)->sa_family != AF_INET6)
 437                         ROUTE_RELEASE(&in6p->in6p_route);
 438
 439                 /* Copy the cached route and take an extra reference */
 440                 in6p_route_copyout(in6p, &ro);
 441
 442                 set_packet_service_class(m, so, sotc, PKT_SCF_IPV6);
 443
 444                 m->m_pkthdr.pkt_flowsrc = FLOWSRC_INPCB;
 445                 m->m_pkthdr.pkt_flowid = in6p->inp_flowhash;
 446                 m->m_pkthdr.pkt_proto = IPPROTO_UDP;
 447                 m->m_pkthdr.pkt_flags |= (PKTF_FLOW_ID | PKTF_FLOW_LOCALSRC);
 448                 if (flowadv)
 449                         m->m_pkthdr.pkt_flags |= PKTF_FLOW_ADV;
 450
 451                 im6o = in6p->in6p_moptions;
 452                 if (im6o != NULL) {
 453                         IM6O_LOCK(im6o);
 454                         IM6O_ADDREF_LOCKED(im6o);
 455                         if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
 456                             im6o->im6o_multicast_ifp != NULL) {
 457                                 in6p->in6p_last_outifp =
 458                                     im6o->im6o_multicast_ifp;
 459                         }
 460                         IM6O_UNLOCK(im6o);
 461                 }
 462
 463                 in6p->inp_sndinprog_cnt++;
 464
 465                 socket_unlock(so, 0);
 466                 error = ip6_output(m, optp, &ro, flags, im6o, NULL, &ip6oa);
 467                 m = NULL;
 468                 socket_lock(so, 0);
 469
 470                 if (im6o != NULL)
 471                         IM6O_REMREF(im6o);
 472
 473                 if (error == 0 && nstat_collect) {
 474                         boolean_t cell, wifi, wired;
 475
 476                         if (in6p->in6p_route.ro_rt != NULL) {
 477                                 cell = IFNET_IS_CELLULAR(in6p->in6p_route.
 478                                     ro_rt->rt_ifp);
 479                                 wifi = (!cell && IFNET_IS_WIFI(in6p->in6p_route.
 480                                     ro_rt->rt_ifp));
 481                                 wired = (!wifi && IFNET_IS_WIRED(in6p->in6p_route.
 482                                     ro_rt->rt_ifp));
 483                         } else {
 484                                 cell = wifi = wired = FALSE;
 485                         }
 486                         INP_ADD_STAT(in6p, cell, wifi, wired, txpackets, 1);
 487                         INP_ADD_STAT(in6p, cell, wifi, wired, txbytes, ulen);
 488                         inp_set_activity_bitmap(in6p);
 489                 }
 490
 491                 if (flowadv && (adv->code == FADV_FLOW_CONTROLLED ||
 492                     adv->code == FADV_SUSPENDED)) {
 493                         /*
 494                          * Return an error to indicate
 495                          * that the packet has been dropped.
 496                          */
 497                         error = ENOBUFS;
 498                         inp_set_fc_state(in6p, adv->code);
 499                 }
 500
 501                 VERIFY(in6p->inp_sndinprog_cnt > 0);
 502                 if ( --in6p->inp_sndinprog_cnt == 0)
 503                         in6p->inp_flags &= ~(INP_FC_FEEDBACK);
 504
 505                 if (ro.ro_rt != NULL) {
 506                         struct ifnet *outif = ro.ro_rt->rt_ifp;
 507
 508                         so->so_pktheadroom = P2ROUNDUP(
 509                             sizeof(struct udphdr) +
 510                             hlen +
 511                             ifnet_hdrlen(outif) +
 512                             ifnet_mbuf_packetpreamblelen(outif),
 513                             sizeof(u_int32_t));
 514                 }
 515
 516                 /* Synchronize PCB cached route */
 517                 in6p_route_copyin(in6p, &ro);
 518
 519                 if (in6p->in6p_route.ro_rt != NULL) {
 520                         struct rtentry *rt = in6p->in6p_route.ro_rt;
 521                         struct ifnet *outif;
 522
 523                         if (rt->rt_flags & RTF_MULTICAST)
 524                                 rt = NULL;      /* unusable */
 525
 526                         /*
 527                          * Always discard the cached route for unconnected
 528                          * socket or if it is a multicast route.
 529                          */
 530                         if (rt == NULL)
 531                                 ROUTE_RELEASE(&in6p->in6p_route);
 532
 533                         /*
 534                          * If the destination route is unicast, update outif
 535                          * with that of the route interface used by IP.
 536                          */
 537                         if (rt != NULL &&
 538                             (outif = rt->rt_ifp) != in6p->in6p_last_outifp) {
 539                                 in6p->in6p_last_outifp = outif;
 540
 541                                 so->so_pktheadroom = P2ROUNDUP(
 542                                     sizeof(struct udphdr) +
 543                                     hlen +
 544                                     ifnet_hdrlen(outif) +
 545                                     ifnet_mbuf_packetpreamblelen(outif),
 546                                     sizeof(u_int32_t));
 547                         }
 548                 } else {
 549                         ROUTE_RELEASE(&in6p->in6p_route);
 550                 }
 551
 552                 /*
 553                  * If output interface was cellular/expensive, and this
 554                  * socket is denied access to it, generate an event.
 555                  */
 556                 if (error != 0 && (ip6oa.ip6oa_retflags & IP6OARF_IFDENIED) &&
 557                     (INP_NO_CELLULAR(in6p) || INP_NO_EXPENSIVE(in6p)))
 558                         soevent(in6p->inp_socket, (SO_FILT_HINT_LOCKED|
 559                             SO_FILT_HINT_IFDENIED));
 560                 break;
 561         case AF_INET:
 562                 error = EAFNOSUPPORT;
 563                 goto release;
 564         }
 565         goto releaseopt;
 566
 567 release:
 568         if (m != NULL)
 569                 m_freem(m);
 570
 571 releaseopt:
 572         if (control != NULL) {
 573                 if (optp == &opt)
 574                         ip6_clearpktopts(optp, -1);
 575                 m_freem(control);
 576         }
 577         return (error);
 578 }