sys/netinet/ip_input.c

   1 /*-
   2  * Copyright (c) 1982, 1986, 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
  30  * $FreeBSD$
  31  */
  32
  33 #include "opt_bootp.h"
  34 #include "opt_ipfw.h"
  35 #include "opt_ipstealth.h"
  36 #include "opt_ipsec.h"
  37 #include "opt_mac.h"
  38
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/callout.h>
  42 #include <sys/mac.h>
  43 #include <sys/mbuf.h>
  44 #include <sys/malloc.h>
  45 #include <sys/domain.h>
  46 #include <sys/protosw.h>
  47 #include <sys/socket.h>
  48 #include <sys/time.h>
  49 #include <sys/kernel.h>
  50 #include <sys/syslog.h>
  51 #include <sys/sysctl.h>
  52
  53 #include <net/pfil.h>
  54 #include <net/if.h>
  55 #include <net/if_types.h>
  56 #include <net/if_var.h>
  57 #include <net/if_dl.h>
  58 #include <net/route.h>
  59 #include <net/netisr.h>
  60
  61 #include <netinet/in.h>
  62 #include <netinet/in_systm.h>
  63 #include <netinet/in_var.h>
  64 #include <netinet/ip.h>
  65 #include <netinet/in_pcb.h>
  66 #include <netinet/ip_var.h>
  67 #include <netinet/ip_icmp.h>
  68 #include <machine/in_cksum.h>
  69
  70 #include <sys/socketvar.h>
  71
  72 /* XXX: Temporary until ipfw_ether and ipfw_bridge are converted. */
  73 #include <netinet/ip_fw.h>
  74 #include <netinet/ip_dummynet.h>
  75
  76 #ifdef IPSEC
  77 #include <netinet6/ipsec.h>
  78 #include <netkey/key.h>
  79 #endif
  80
  81 #ifdef FAST_IPSEC
  82 #include <netipsec/ipsec.h>
  83 #include <netipsec/key.h>
  84 #endif
  85
  86 int rsvp_on = 0;
  87
  88 int     ipforwarding = 0;
  89 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
  90     &ipforwarding, 0, "Enable IP forwarding between interfaces");
  91
  92 static int      ipsendredirects = 1; /* XXX */
  93 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
  94     &ipsendredirects, 0, "Enable sending IP redirects");
  95
  96 int     ip_defttl = IPDEFTTL;
  97 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
  98     &ip_defttl, 0, "Maximum TTL on IP packets");
  99
 100 static int      ip_dosourceroute = 0;
 101 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
 102     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
 103
 104 static int      ip_acceptsourceroute = 0;
 105 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
 106     CTLFLAG_RW, &ip_acceptsourceroute, 0,
 107     "Enable accepting source routed IP packets");
 108
 109 int             ip_doopts = 1;  /* 0 = ignore, 1 = process, 2 = reject */
 110 SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
 111     &ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
 112
 113 static int      ip_keepfaith = 0;
 114 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
 115         &ip_keepfaith,  0,
 116         "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
 117
 118 static int    nipq = 0;         /* total # of reass queues */
 119 static int    maxnipq;
 120 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
 121         &maxnipq, 0,
 122         "Maximum number of IPv4 fragment reassembly queue entries");
 123
 124 static int    maxfragsperpacket;
 125 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
 126         &maxfragsperpacket, 0,
 127         "Maximum number of IPv4 fragments allowed per packet");
 128
 129 static int      ip_sendsourcequench = 0;
 130 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
 131         &ip_sendsourcequench, 0,
 132         "Enable the transmission of source quench packets");
 133
 134 int     ip_do_randomid = 0;
 135 SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW,
 136         &ip_do_randomid, 0,
 137         "Assign random ip_id values");
 138
 139 /*
 140  * XXX - Setting ip_checkinterface mostly implements the receive side of
 141  * the Strong ES model described in RFC 1122, but since the routing table
 142  * and transmit implementation do not implement the Strong ES model,
 143  * setting this to 1 results in an odd hybrid.
 144  *
 145  * XXX - ip_checkinterface currently must be disabled if you use ipnat
 146  * to translate the destination address to another local interface.
 147  *
 148  * XXX - ip_checkinterface must be disabled if you add IP aliases
 149  * to the loopback interface instead of the interface where the
 150  * packets for those addresses are received.
 151  */
 152 static int      ip_checkinterface = 0;
 153 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
 154     &ip_checkinterface, 0, "Verify packet arrives on correct interface");
 155
 156 #ifdef DIAGNOSTIC
 157 static int      ipprintfs = 0;
 158 #endif
 159
 160 struct pfil_head inet_pfil_hook;        /* Packet filter hooks */
 161
 162 static struct   ifqueue ipintrq;
 163 static int      ipqmaxlen = IFQ_MAXLEN;
 164
 165 extern  struct domain inetdomain;
 166 extern  struct protosw inetsw[];
 167 u_char  ip_protox[IPPROTO_MAX];
 168 struct  in_ifaddrhead in_ifaddrhead;            /* first inet address */
 169 struct  in_ifaddrhashhead *in_ifaddrhashtbl;    /* inet addr hash table  */
 170 u_long  in_ifaddrhmask;                         /* mask for hash table */
 171
 172 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
 173     &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
 174 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
 175     &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
 176
 177 struct ipstat ipstat;
 178 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
 179     &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)");
 180
 181 /* Packet reassembly stuff */
 182 #define IPREASS_NHASH_LOG2      6
 183 #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
 184 #define IPREASS_HMASK           (IPREASS_NHASH - 1)
 185 #define IPREASS_HASH(x,y) \
 186         (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
 187
 188 static TAILQ_HEAD(ipqhead, ipq) ipq[IPREASS_NHASH];
 189 struct mtx ipqlock;
 190 struct callout ipport_tick_callout;
 191
 192 #define IPQ_LOCK()      mtx_lock(&ipqlock)
 193 #define IPQ_UNLOCK()    mtx_unlock(&ipqlock)
 194 #define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF)
 195 #define IPQ_LOCK_ASSERT()       mtx_assert(&ipqlock, MA_OWNED)
 196
 197 #ifdef IPCTL_DEFMTU
 198 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
 199     &ip_mtu, 0, "Default MTU");
 200 #endif
 201
 202 #ifdef IPSTEALTH
 203 int     ipstealth = 0;
 204 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
 205     &ipstealth, 0, "");
 206 #endif
 207
 208 /*
 209  * ipfw_ether and ipfw_bridge hooks.
 210  * XXX: Temporary until those are converted to pfil_hooks as well.
 211  */
 212 ip_fw_chk_t *ip_fw_chk_ptr = NULL;
 213 ip_dn_io_t *ip_dn_io_ptr = NULL;
 214 int fw_enable = 1;
 215 int fw_one_pass = 1;
 216
 217 /*
 218  * XXX this is ugly.  IP options source routing magic.
 219  */
 220 struct ipoptrt {
 221         struct  in_addr dst;                    /* final destination */
 222         char    nop;                            /* one NOP to align */
 223         char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
 224         struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
 225 };
 226
 227 struct ipopt_tag {
 228         struct  m_tag tag;
 229         int     ip_nhops;
 230         struct  ipoptrt ip_srcrt;
 231 };
 232
 233 static void     save_rte(struct mbuf *, u_char *, struct in_addr);
 234 static int      ip_dooptions(struct mbuf *m, int);
 235 static void     ip_forward(struct mbuf *m, int srcrt);
 236 static void     ip_freef(struct ipqhead *, struct ipq *);
 237
 238 /*
 239  * IP initialization: fill in IP protocol switch table.
 240  * All protocols not implemented in kernel go to raw IP protocol handler.
 241  */
 242 void
 243 ip_init()
 244 {
 245         register struct protosw *pr;
 246         register int i;
 247
 248         TAILQ_INIT(&in_ifaddrhead);
 249         in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask);
 250         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 251         if (pr == NULL)
 252                 panic("ip_init: PF_INET not found");
 253
 254         /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */
 255         for (i = 0; i < IPPROTO_MAX; i++)
 256                 ip_protox[i] = pr - inetsw;
 257         /*
 258          * Cycle through IP protocols and put them into the appropriate place
 259          * in ip_protox[].
 260          */
 261         for (pr = inetdomain.dom_protosw;
 262             pr < inetdomain.dom_protoswNPROTOSW; pr++)
 263                 if (pr->pr_domain->dom_family == PF_INET &&
 264                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
 265                         /* Be careful to only index valid IP protocols. */
 266                         if (pr->pr_protocol <= IPPROTO_MAX)
 267                                 ip_protox[pr->pr_protocol] = pr - inetsw;
 268                 }
 269
 270         /* Initialize packet filter hooks. */
 271         inet_pfil_hook.ph_type = PFIL_TYPE_AF;
 272         inet_pfil_hook.ph_af = AF_INET;
 273         if ((i = pfil_head_register(&inet_pfil_hook)) != 0)
 274                 printf("%s: WARNING: unable to register pfil hook, "
 275                         "error %d\n", __func__, i);
 276
 277         /* Initialize IP reassembly queue. */
 278         IPQ_LOCK_INIT();
 279         for (i = 0; i < IPREASS_NHASH; i++)
 280             TAILQ_INIT(&ipq[i]);
 281         maxnipq = nmbclusters / 32;
 282         maxfragsperpacket = 16;
 283
 284         /* Start ipport_tick. */
 285         callout_init(&ipport_tick_callout, CALLOUT_MPSAFE);
 286         ipport_tick(NULL);
 287         EVENTHANDLER_REGISTER(shutdown_pre_sync, ip_fini, NULL,
 288                 SHUTDOWN_PRI_DEFAULT);
 289
 290         /* Initialize various other remaining things. */
 291         ip_id = time_second & 0xffff;
 292         ipintrq.ifq_maxlen = ipqmaxlen;
 293         mtx_init(&ipintrq.ifq_mtx, "ip_inq", NULL, MTX_DEF);
 294         netisr_register(NETISR_IP, ip_input, &ipintrq, NETISR_MPSAFE);
 295 }
 296
 297 void ip_fini(xtp)
 298         void *xtp;
 299 {
 300         callout_stop(&ipport_tick_callout);
 301 }
 302
 303 /*
 304  * Ip input routine.  Checksum and byte swap header.  If fragmented
 305  * try to reassemble.  Process options.  Pass to next level.
 306  */
 307 void
 308 ip_input(struct mbuf *m)
 309 {
 310         struct ip *ip = NULL;
 311         struct in_ifaddr *ia = NULL;
 312         struct ifaddr *ifa;
 313         int    checkif, hlen = 0;
 314         u_short sum;
 315         int dchg = 0;                           /* dest changed after fw */
 316         struct in_addr odst;                    /* original dst address */
 317 #ifdef FAST_IPSEC
 318         struct m_tag *mtag;
 319         struct tdb_ident *tdbi;
 320         struct secpolicy *sp;
 321         int s, error;
 322 #endif /* FAST_IPSEC */
 323
 324         M_ASSERTPKTHDR(m);
 325
 326         if (m->m_flags & M_FASTFWD_OURS) {
 327                 /*
 328                  * Firewall or NAT changed destination to local.
 329                  * We expect ip_len and ip_off to be in host byte order.
 330                  */
 331                 m->m_flags &= ~M_FASTFWD_OURS;
 332                 /* Set up some basics that will be used later. */
 333                 ip = mtod(m, struct ip *);
 334                 hlen = ip->ip_hl << 2;
 335                 goto ours;
 336         }
 337
 338         ipstat.ips_total++;
 339
 340         if (m->m_pkthdr.len < sizeof(struct ip))
 341                 goto tooshort;
 342
 343         if (m->m_len < sizeof (struct ip) &&
 344             (m = m_pullup(m, sizeof (struct ip))) == NULL) {
 345                 ipstat.ips_toosmall++;
 346                 return;
 347         }
 348         ip = mtod(m, struct ip *);
 349
 350         if (ip->ip_v != IPVERSION) {
 351                 ipstat.ips_badvers++;
 352                 goto bad;
 353         }
 354
 355         hlen = ip->ip_hl << 2;
 356         if (hlen < sizeof(struct ip)) { /* minimum header length */
 357                 ipstat.ips_badhlen++;
 358                 goto bad;
 359         }
 360         if (hlen > m->m_len) {
 361                 if ((m = m_pullup(m, hlen)) == NULL) {
 362                         ipstat.ips_badhlen++;
 363                         return;
 364                 }
 365                 ip = mtod(m, struct ip *);
 366         }
 367
 368         /* 127/8 must not appear on wire - RFC1122 */
 369         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
 370             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
 371                 if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
 372                         ipstat.ips_badaddr++;
 373                         goto bad;
 374                 }
 375         }
 376
 377         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
 378                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
 379         } else {
 380                 if (hlen == sizeof(struct ip)) {
 381                         sum = in_cksum_hdr(ip);
 382                 } else {
 383                         sum = in_cksum(m, hlen);
 384                 }
 385         }
 386         if (sum) {
 387                 ipstat.ips_badsum++;
 388                 goto bad;
 389         }
 390
 391 #ifdef ALTQ
 392         if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
 393                 /* packet is dropped by traffic conditioner */
 394                 return;
 395 #endif
 396
 397         /*
 398          * Convert fields to host representation.
 399          */
 400         ip->ip_len = ntohs(ip->ip_len);
 401         if (ip->ip_len < hlen) {
 402                 ipstat.ips_badlen++;
 403                 goto bad;
 404         }
 405         ip->ip_off = ntohs(ip->ip_off);
 406
 407         /*
 408          * Check that the amount of data in the buffers
 409          * is as at least much as the IP header would have us expect.
 410          * Trim mbufs if longer than we expect.
 411          * Drop packet if shorter than we expect.
 412          */
 413         if (m->m_pkthdr.len < ip->ip_len) {
 414 tooshort:
 415                 ipstat.ips_tooshort++;
 416                 goto bad;
 417         }
 418         if (m->m_pkthdr.len > ip->ip_len) {
 419                 if (m->m_len == m->m_pkthdr.len) {
 420                         m->m_len = ip->ip_len;
 421                         m->m_pkthdr.len = ip->ip_len;
 422                 } else
 423                         m_adj(m, ip->ip_len - m->m_pkthdr.len);
 424         }
 425 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
 426         /*
 427          * Bypass packet filtering for packets from a tunnel (gif).
 428          */
 429         if (ipsec_getnhist(m))
 430                 goto passin;
 431 #endif
 432 #if defined(FAST_IPSEC) && !defined(IPSEC_FILTERGIF)
 433         /*
 434          * Bypass packet filtering for packets from a tunnel (gif).
 435          */
 436         if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
 437                 goto passin;
 438 #endif
 439
 440         /*
 441          * Run through list of hooks for input packets.
 442          *
 443          * NB: Beware of the destination address changing (e.g.
 444          *     by NAT rewriting).  When this happens, tell
 445          *     ip_forward to do the right thing.
 446          */
 447
 448         /* Jump over all PFIL processing if hooks are not active. */
 449         if (inet_pfil_hook.ph_busy_count == -1)
 450                 goto passin;
 451
 452         odst = ip->ip_dst;
 453         if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
 454             PFIL_IN, NULL) != 0)
 455                 return;
 456         if (m == NULL)                  /* consumed by filter */
 457                 return;
 458
 459         ip = mtod(m, struct ip *);
 460         dchg = (odst.s_addr != ip->ip_dst.s_addr);
 461
 462 #ifdef IPFIREWALL_FORWARD
 463         if (m->m_flags & M_FASTFWD_OURS) {
 464                 m->m_flags &= ~M_FASTFWD_OURS;
 465                 goto ours;
 466         }
 467         dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL);
 468 #endif /* IPFIREWALL_FORWARD */
 469
 470 passin:
 471         /*
 472          * Process options and, if not destined for us,
 473          * ship it on.  ip_dooptions returns 1 when an
 474          * error was detected (causing an icmp message
 475          * to be sent and the original packet to be freed).
 476          */
 477         if (hlen > sizeof (struct ip) && ip_dooptions(m, 0))
 478                 return;
 479
 480         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
 481          * matter if it is destined to another node, or whether it is
 482          * a multicast one, RSVP wants it! and prevents it from being forwarded
 483          * anywhere else. Also checks if the rsvp daemon is running before
 484          * grabbing the packet.
 485          */
 486         if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
 487                 goto ours;
 488
 489         /*
 490          * Check our list of addresses, to see if the packet is for us.
 491          * If we don't have any addresses, assume any unicast packet
 492          * we receive might be for us (and let the upper layers deal
 493          * with it).
 494          */
 495         if (TAILQ_EMPTY(&in_ifaddrhead) &&
 496             (m->m_flags & (M_MCAST|M_BCAST)) == 0)
 497                 goto ours;
 498
 499         /*
 500          * Enable a consistency check between the destination address
 501          * and the arrival interface for a unicast packet (the RFC 1122
 502          * strong ES model) if IP forwarding is disabled and the packet
 503          * is not locally generated and the packet is not subject to
 504          * 'ipfw fwd'.
 505          *
 506          * XXX - Checking also should be disabled if the destination
 507          * address is ipnat'ed to a different interface.
 508          *
 509          * XXX - Checking is incompatible with IP aliases added
 510          * to the loopback interface instead of the interface where
 511          * the packets are received.
 512          */
 513         checkif = ip_checkinterface && (ipforwarding == 0) &&
 514             m->m_pkthdr.rcvif != NULL &&
 515             ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) &&
 516             (dchg == 0);
 517
 518         /*
 519          * Check for exact addresses in the hash bucket.
 520          */
 521         LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
 522                 /*
 523                  * If the address matches, verify that the packet
 524                  * arrived via the correct interface if checking is
 525                  * enabled.
 526                  */
 527                 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr &&
 528                     (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
 529                         goto ours;
 530         }
 531         /*
 532          * Check for broadcast addresses.
 533          *
 534          * Only accept broadcast packets that arrive via the matching
 535          * interface.  Reception of forwarded directed broadcasts would
 536          * be handled via ip_forward() and ether_output() with the loopback
 537          * into the stack for SIMPLEX interfaces handled by ether_output().
 538          */
 539         if (m->m_pkthdr.rcvif != NULL &&
 540             m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
 541                 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
 542                         if (ifa->ifa_addr->sa_family != AF_INET)
 543                                 continue;
 544                         ia = ifatoia(ifa);
 545                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 546                             ip->ip_dst.s_addr)
 547                                 goto ours;
 548                         if (ia->ia_netbroadcast.s_addr == ip->ip_dst.s_addr)
 549                                 goto ours;
 550 #ifdef BOOTP_COMPAT
 551                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
 552                                 goto ours;
 553 #endif
 554                 }
 555         }
 556         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
 557                 struct in_multi *inm;
 558                 if (ip_mrouter) {
 559                         /*
 560                          * If we are acting as a multicast router, all
 561                          * incoming multicast packets are passed to the
 562                          * kernel-level multicast forwarding function.
 563                          * The packet is returned (relatively) intact; if
 564                          * ip_mforward() returns a non-zero value, the packet
 565                          * must be discarded, else it may be accepted below.
 566                          */
 567                         if (ip_mforward &&
 568                             ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
 569                                 ipstat.ips_cantforward++;
 570                                 m_freem(m);
 571                                 return;
 572                         }
 573
 574                         /*
 575                          * The process-level routing daemon needs to receive
 576                          * all multicast IGMP packets, whether or not this
 577                          * host belongs to their destination groups.
 578                          */
 579                         if (ip->ip_p == IPPROTO_IGMP)
 580                                 goto ours;
 581                         ipstat.ips_forward++;
 582                 }
 583                 /*
 584                  * See if we belong to the destination multicast group on the
 585                  * arrival interface.
 586                  */
 587                 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
 588                 if (inm == NULL) {
 589                         ipstat.ips_notmember++;
 590                         m_freem(m);
 591                         return;
 592                 }
 593                 goto ours;
 594         }
 595         if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
 596                 goto ours;
 597         if (ip->ip_dst.s_addr == INADDR_ANY)
 598                 goto ours;
 599
 600         /*
 601          * FAITH(Firewall Aided Internet Translator)
 602          */
 603         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 604                 if (ip_keepfaith) {
 605                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
 606                                 goto ours;
 607                 }
 608                 m_freem(m);
 609                 return;
 610         }
 611
 612         /*
 613          * Not for us; forward if possible and desirable.
 614          */
 615         if (ipforwarding == 0) {
 616                 ipstat.ips_cantforward++;
 617                 m_freem(m);
 618         } else {
 619 #ifdef IPSEC
 620                 /*
 621                  * Enforce inbound IPsec SPD.
 622                  */
 623                 if (ipsec4_in_reject(m, NULL)) {
 624                         ipsecstat.in_polvio++;
 625                         goto bad;
 626                 }
 627 #endif /* IPSEC */
 628 #ifdef FAST_IPSEC
 629                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 630                 s = splnet();
 631                 if (mtag != NULL) {
 632                         tdbi = (struct tdb_ident *)(mtag + 1);
 633                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 634                 } else {
 635                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 636                                                    IP_FORWARDING, &error);
 637                 }
 638                 if (sp == NULL) {       /* NB: can happen if error */
 639                         splx(s);
 640                         /*XXX error stat???*/
 641                         DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 642                         goto bad;
 643                 }
 644
 645                 /*
 646                  * Check security policy against packet attributes.
 647                  */
 648                 error = ipsec_in_reject(sp, m);
 649                 KEY_FREESP(&sp);
 650                 splx(s);
 651                 if (error) {
 652                         ipstat.ips_cantforward++;
 653                         goto bad;
 654                 }
 655 #endif /* FAST_IPSEC */
 656                 ip_forward(m, dchg);
 657         }
 658         return;
 659
 660 ours:
 661 #ifdef IPSTEALTH
 662         /*
 663          * IPSTEALTH: Process non-routing options only
 664          * if the packet is destined for us.
 665          */
 666         if (ipstealth && hlen > sizeof (struct ip) &&
 667             ip_dooptions(m, 1))
 668                 return;
 669 #endif /* IPSTEALTH */
 670
 671         /* Count the packet in the ip address stats */
 672         if (ia != NULL) {
 673                 ia->ia_ifa.if_ipackets++;
 674                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
 675         }
 676
 677         /*
 678          * Attempt reassembly; if it succeeds, proceed.
 679          * ip_reass() will return a different mbuf.
 680          */
 681         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 682                 m = ip_reass(m);
 683                 if (m == NULL)
 684                         return;
 685                 ip = mtod(m, struct ip *);
 686                 /* Get the header length of the reassembled packet */
 687                 hlen = ip->ip_hl << 2;
 688         }
 689
 690         /*
 691          * Further protocols expect the packet length to be w/o the
 692          * IP header.
 693          */
 694         ip->ip_len -= hlen;
 695
 696 #ifdef IPSEC
 697         /*
 698          * enforce IPsec policy checking if we are seeing last header.
 699          * note that we do not visit this with protocols with pcb layer
 700          * code - like udp/tcp/raw ip.
 701          */
 702         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
 703             ipsec4_in_reject(m, NULL)) {
 704                 ipsecstat.in_polvio++;
 705                 goto bad;
 706         }
 707 #endif
 708 #if FAST_IPSEC
 709         /*
 710          * enforce IPsec policy checking if we are seeing last header.
 711          * note that we do not visit this with protocols with pcb layer
 712          * code - like udp/tcp/raw ip.
 713          */
 714         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 715                 /*
 716                  * Check if the packet has already had IPsec processing
 717                  * done.  If so, then just pass it along.  This tag gets
 718                  * set during AH, ESP, etc. input handling, before the
 719                  * packet is returned to the ip input queue for delivery.
 720                  */
 721                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 722                 s = splnet();
 723                 if (mtag != NULL) {
 724                         tdbi = (struct tdb_ident *)(mtag + 1);
 725                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 726                 } else {
 727                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 728                                                    IP_FORWARDING, &error);
 729                 }
 730                 if (sp != NULL) {
 731                         /*
 732                          * Check security policy against packet attributes.
 733                          */
 734                         error = ipsec_in_reject(sp, m);
 735                         KEY_FREESP(&sp);
 736                 } else {
 737                         /* XXX error stat??? */
 738                         error = EINVAL;
 739 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 740                         goto bad;
 741                 }
 742                 splx(s);
 743                 if (error)
 744                         goto bad;
 745         }
 746 #endif /* FAST_IPSEC */
 747
 748         /*
 749          * Switch out to protocol's input routine.
 750          */
 751         ipstat.ips_delivered++;
 752
 753         (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
 754         return;
 755 bad:
 756         m_freem(m);
 757 }
 758
 759 /*
 760  * Take incoming datagram fragment and try to reassemble it into
 761  * whole datagram.  If the argument is the first fragment or one
 762  * in between the function will return NULL and store the mbuf
 763  * in the fragment chain.  If the argument is the last fragment
 764  * the packet will be reassembled and the pointer to the new
 765  * mbuf returned for further processing.  Only m_tags attached
 766  * to the first packet/fragment are preserved.
 767  * The IP header is *NOT* adjusted out of iplen.
 768  */
 769
 770 struct mbuf *
 771 ip_reass(struct mbuf *m)
 772 {
 773         struct ip *ip;
 774         struct mbuf *p, *q, *nq, *t;
 775         struct ipq *fp = NULL;
 776         struct ipqhead *head;
 777         int i, hlen, next;
 778         u_int8_t ecn, ecn0;
 779         u_short hash;
 780
 781         /* If maxnipq is 0, never accept fragments. */
 782         if (maxnipq == 0) {
 783                 ipstat.ips_fragments++;
 784                 ipstat.ips_fragdropped++;
 785                 m_freem(m);
 786                 return (NULL);
 787         }
 788
 789         ip = mtod(m, struct ip *);
 790         hlen = ip->ip_hl << 2;
 791
 792         hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
 793         head = &ipq[hash];
 794         IPQ_LOCK();
 795
 796         /*
 797          * Look for queue of fragments
 798          * of this datagram.
 799          */
 800         TAILQ_FOREACH(fp, head, ipq_list)
 801                 if (ip->ip_id == fp->ipq_id &&
 802                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 803                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 804 #ifdef MAC
 805                     mac_fragment_match(m, fp) &&
 806 #endif
 807                     ip->ip_p == fp->ipq_p)
 808                         goto found;
 809
 810         fp = NULL;
 811
 812         /*
 813          * Enforce upper bound on number of fragmented packets
 814          * for which we attempt reassembly;
 815          * If maxnipq is -1, accept all fragments without limitation.
 816          */
 817         if ((nipq > maxnipq) && (maxnipq > 0)) {
 818                 /*
 819                  * drop something from the tail of the current queue
 820                  * before proceeding further
 821                  */
 822                 struct ipq *q = TAILQ_LAST(head, ipqhead);
 823                 if (q == NULL) {   /* gak */
 824                         for (i = 0; i < IPREASS_NHASH; i++) {
 825                                 struct ipq *r = TAILQ_LAST(&ipq[i], ipqhead);
 826                                 if (r) {
 827                                         ipstat.ips_fragtimeout += r->ipq_nfrags;
 828                                         ip_freef(&ipq[i], r);
 829                                         break;
 830                                 }
 831                         }
 832                 } else {
 833                         ipstat.ips_fragtimeout += q->ipq_nfrags;
 834                         ip_freef(head, q);
 835                 }
 836         }
 837
 838 found:
 839         /*
 840          * Adjust ip_len to not reflect header,
 841          * convert offset of this to bytes.
 842          */
 843         ip->ip_len -= hlen;
 844         if (ip->ip_off & IP_MF) {
 845                 /*
 846                  * Make sure that fragments have a data length
 847                  * that's a non-zero multiple of 8 bytes.
 848                  */
 849                 if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
 850                         ipstat.ips_toosmall++; /* XXX */
 851                         goto dropfrag;
 852                 }
 853                 m->m_flags |= M_FRAG;
 854         } else
 855                 m->m_flags &= ~M_FRAG;
 856         ip->ip_off <<= 3;
 857
 858
 859         /*
 860          * Attempt reassembly; if it succeeds, proceed.
 861          * ip_reass() will return a different mbuf.
 862          */
 863         ipstat.ips_fragments++;
 864         m->m_pkthdr.header = ip;
 865
 866         /* Previous ip_reass() started here. */
 867         /*
 868          * Presence of header sizes in mbufs
 869          * would confuse code below.
 870          */
 871         m->m_data += hlen;
 872         m->m_len -= hlen;
 873
 874         /*
 875          * If first fragment to arrive, create a reassembly queue.
 876          */
 877         if (fp == NULL) {
 878                 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
 879                         goto dropfrag;
 880                 fp = mtod(t, struct ipq *);
 881 #ifdef MAC
 882                 if (mac_init_ipq(fp, M_NOWAIT) != 0) {
 883                         m_free(t);
 884                         goto dropfrag;
 885                 }
 886                 mac_create_ipq(m, fp);
 887 #endif
 888                 TAILQ_INSERT_HEAD(head, fp, ipq_list);
 889                 nipq++;
 890                 fp->ipq_nfrags = 1;
 891                 fp->ipq_ttl = IPFRAGTTL;
 892                 fp->ipq_p = ip->ip_p;
 893                 fp->ipq_id = ip->ip_id;
 894                 fp->ipq_src = ip->ip_src;
 895                 fp->ipq_dst = ip->ip_dst;
 896                 fp->ipq_frags = m;
 897                 m->m_nextpkt = NULL;
 898                 goto inserted;
 899         } else {
 900                 fp->ipq_nfrags++;
 901 #ifdef MAC
 902                 mac_update_ipq(m, fp);
 903 #endif
 904         }
 905
 906 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.header))
 907
 908         /*
 909          * Handle ECN by comparing this segment with the first one;
 910          * if CE is set, do not lose CE.
 911          * drop if CE and not-ECT are mixed for the same packet.
 912          */
 913         ecn = ip->ip_tos & IPTOS_ECN_MASK;
 914         ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
 915         if (ecn == IPTOS_ECN_CE) {
 916                 if (ecn0 == IPTOS_ECN_NOTECT)
 917                         goto dropfrag;
 918                 if (ecn0 != IPTOS_ECN_CE)
 919                         GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
 920         }
 921         if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
 922                 goto dropfrag;
 923
 924         /*
 925          * Find a segment which begins after this one does.
 926          */
 927         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
 928                 if (GETIP(q)->ip_off > ip->ip_off)
 929                         break;
 930
 931         /*
 932          * If there is a preceding segment, it may provide some of
 933          * our data already.  If so, drop the data from the incoming
 934          * segment.  If it provides all of our data, drop us, otherwise
 935          * stick new segment in the proper place.
 936          *
 937          * If some of the data is dropped from the the preceding
 938          * segment, then it's checksum is invalidated.
 939          */
 940         if (p) {
 941                 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
 942                 if (i > 0) {
 943                         if (i >= ip->ip_len)
 944                                 goto dropfrag;
 945                         m_adj(m, i);
 946                         m->m_pkthdr.csum_flags = 0;
 947                         ip->ip_off += i;
 948                         ip->ip_len -= i;
 949                 }
 950                 m->m_nextpkt = p->m_nextpkt;
 951                 p->m_nextpkt = m;
 952         } else {
 953                 m->m_nextpkt = fp->ipq_frags;
 954                 fp->ipq_frags = m;
 955         }
 956
 957         /*
 958          * While we overlap succeeding segments trim them or,
 959          * if they are completely covered, dequeue them.
 960          */
 961         for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
 962              q = nq) {
 963                 i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off;
 964                 if (i < GETIP(q)->ip_len) {
 965                         GETIP(q)->ip_len -= i;
 966                         GETIP(q)->ip_off += i;
 967                         m_adj(q, i);
 968                         q->m_pkthdr.csum_flags = 0;
 969                         break;
 970                 }
 971                 nq = q->m_nextpkt;
 972                 m->m_nextpkt = nq;
 973                 ipstat.ips_fragdropped++;
 974                 fp->ipq_nfrags--;
 975                 m_freem(q);
 976         }
 977
 978 inserted:
 979
 980         /*
 981          * Check for complete reassembly and perform frag per packet
 982          * limiting.
 983          *
 984          * Frag limiting is performed here so that the nth frag has
 985          * a chance to complete the packet before we drop the packet.
 986          * As a result, n+1 frags are actually allowed per packet, but
 987          * only n will ever be stored. (n = maxfragsperpacket.)
 988          *
 989          */
 990         next = 0;
 991         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
 992                 if (GETIP(q)->ip_off != next) {
 993                         if (fp->ipq_nfrags > maxfragsperpacket) {
 994                                 ipstat.ips_fragdropped += fp->ipq_nfrags;
 995                                 ip_freef(head, fp);
 996                         }
 997                         goto done;
 998                 }
 999                 next += GETIP(q)->ip_len;
1000         }
1001         /* Make sure the last packet didn't have the IP_MF flag */
1002         if (p->m_flags & M_FRAG) {
1003                 if (fp->ipq_nfrags > maxfragsperpacket) {
1004                         ipstat.ips_fragdropped += fp->ipq_nfrags;
1005                         ip_freef(head, fp);
1006                 }
1007                 goto done;
1008         }
1009
1010         /*
1011          * Reassembly is complete.  Make sure the packet is a sane size.
1012          */
1013         q = fp->ipq_frags;
1014         ip = GETIP(q);
1015         if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
1016                 ipstat.ips_toolong++;
1017                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1018                 ip_freef(head, fp);
1019                 goto done;
1020         }
1021
1022         /*
1023          * Concatenate fragments.
1024          */
1025         m = q;
1026         t = m->m_next;
1027         m->m_next = NULL;
1028         m_cat(m, t);
1029         nq = q->m_nextpkt;
1030         q->m_nextpkt = NULL;
1031         for (q = nq; q != NULL; q = nq) {
1032                 nq = q->m_nextpkt;
1033                 q->m_nextpkt = NULL;
1034                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
1035                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
1036                 m_cat(m, q);
1037         }
1038 #ifdef MAC
1039         mac_create_datagram_from_ipq(fp, m);
1040         mac_destroy_ipq(fp);
1041 #endif
1042
1043         /*
1044          * Create header for new ip packet by modifying header of first
1045          * packet;  dequeue and discard fragment reassembly header.
1046          * Make header visible.
1047          */
1048         ip->ip_len = (ip->ip_hl << 2) + next;
1049         ip->ip_src = fp->ipq_src;
1050         ip->ip_dst = fp->ipq_dst;
1051         TAILQ_REMOVE(head, fp, ipq_list);
1052         nipq--;
1053         (void) m_free(dtom(fp));
1054         m->m_len += (ip->ip_hl << 2);
1055         m->m_data -= (ip->ip_hl << 2);
1056         /* some debugging cruft by sklower, below, will go away soon */
1057         if (m->m_flags & M_PKTHDR)      /* XXX this should be done elsewhere */
1058                 m_fixhdr(m);
1059         ipstat.ips_reassembled++;
1060         IPQ_UNLOCK();
1061         return (m);
1062
1063 dropfrag:
1064         ipstat.ips_fragdropped++;
1065         if (fp != NULL)
1066                 fp->ipq_nfrags--;
1067         m_freem(m);
1068 done:
1069         IPQ_UNLOCK();
1070         return (NULL);
1071
1072 #undef GETIP
1073 }
1074
1075 /*
1076  * Free a fragment reassembly header and all
1077  * associated datagrams.
1078  */
1079 static void
1080 ip_freef(fhp, fp)
1081         struct ipqhead *fhp;
1082         struct ipq *fp;
1083 {
1084         register struct mbuf *q;
1085
1086         IPQ_LOCK_ASSERT();
1087
1088         while (fp->ipq_frags) {
1089                 q = fp->ipq_frags;
1090                 fp->ipq_frags = q->m_nextpkt;
1091                 m_freem(q);
1092         }
1093         TAILQ_REMOVE(fhp, fp, ipq_list);
1094         (void) m_free(dtom(fp));
1095         nipq--;
1096 }
1097
1098 /*
1099  * IP timer processing;
1100  * if a timer expires on a reassembly
1101  * queue, discard it.
1102  */
1103 void
1104 ip_slowtimo()
1105 {
1106         register struct ipq *fp;
1107         int s = splnet();
1108         int i;
1109
1110         IPQ_LOCK();
1111         for (i = 0; i < IPREASS_NHASH; i++) {
1112                 for(fp = TAILQ_FIRST(&ipq[i]); fp;) {
1113                         struct ipq *fpp;
1114
1115                         fpp = fp;
1116                         fp = TAILQ_NEXT(fp, ipq_list);
1117                         if(--fpp->ipq_ttl == 0) {
1118                                 ipstat.ips_fragtimeout += fpp->ipq_nfrags;
1119                                 ip_freef(&ipq[i], fpp);
1120                         }
1121                 }
1122         }
1123         /*
1124          * If we are over the maximum number of fragments
1125          * (due to the limit being lowered), drain off
1126          * enough to get down to the new limit.
1127          */
1128         if (maxnipq >= 0 && nipq > maxnipq) {
1129                 for (i = 0; i < IPREASS_NHASH; i++) {
1130                         while (nipq > maxnipq && !TAILQ_EMPTY(&ipq[i])) {
1131                                 ipstat.ips_fragdropped +=
1132                                     TAILQ_FIRST(&ipq[i])->ipq_nfrags;
1133                                 ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
1134                         }
1135                 }
1136         }
1137         IPQ_UNLOCK();
1138         splx(s);
1139 }
1140
1141 /*
1142  * Drain off all datagram fragments.
1143  */
1144 void
1145 ip_drain()
1146 {
1147         int     i;
1148
1149         IPQ_LOCK();
1150         for (i = 0; i < IPREASS_NHASH; i++) {
1151                 while(!TAILQ_EMPTY(&ipq[i])) {
1152                         ipstat.ips_fragdropped +=
1153                             TAILQ_FIRST(&ipq[i])->ipq_nfrags;
1154                         ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
1155                 }
1156         }
1157         IPQ_UNLOCK();
1158         in_rtqdrain();
1159 }
1160
1161 /*
1162  * The protocol to be inserted into ip_protox[] must be already registered
1163  * in inetsw[], either statically or through pf_proto_register().
1164  */
1165 int
1166 ipproto_register(u_char ipproto)
1167 {
1168         struct protosw *pr;
1169
1170         /* Sanity checks. */
1171         if (ipproto == 0)
1172                 return (EPROTONOSUPPORT);
1173
1174         /*
1175          * The protocol slot must not be occupied by another protocol
1176          * already.  An index pointing to IPPROTO_RAW is unused.
1177          */
1178         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
1179         if (pr == NULL)
1180                 return (EPFNOSUPPORT);
1181         if (ip_protox[ipproto] != pr - inetsw)  /* IPPROTO_RAW */
1182                 return (EEXIST);
1183
1184         /* Find the protocol position in inetsw[] and set the index. */
1185         for (pr = inetdomain.dom_protosw;
1186              pr < inetdomain.dom_protoswNPROTOSW; pr++) {
1187                 if (pr->pr_domain->dom_family == PF_INET &&
1188                     pr->pr_protocol && pr->pr_protocol == ipproto) {
1189                         /* Be careful to only index valid IP protocols. */
1190                         if (pr->pr_protocol <= IPPROTO_MAX) {
1191                                 ip_protox[pr->pr_protocol] = pr - inetsw;
1192                                 return (0);
1193                         } else
1194                                 return (EINVAL);
1195                 }
1196         }
1197         return (EPROTONOSUPPORT);
1198 }
1199
1200 int
1201 ipproto_unregister(u_char ipproto)
1202 {
1203         struct protosw *pr;
1204
1205         /* Sanity checks. */
1206         if (ipproto == 0)
1207                 return (EPROTONOSUPPORT);
1208
1209         /* Check if the protocol was indeed registered. */
1210         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
1211         if (pr == NULL)
1212                 return (EPFNOSUPPORT);
1213         if (ip_protox[ipproto] == pr - inetsw)  /* IPPROTO_RAW */
1214                 return (ENOENT);
1215
1216         /* Reset the protocol slot to IPPROTO_RAW. */
1217         ip_protox[ipproto] = pr - inetsw;
1218         return (0);
1219 }
1220
1221
1222 /*
1223  * Do option processing on a datagram,
1224  * possibly discarding it if bad options are encountered,
1225  * or forwarding it if source-routed.
1226  * The pass argument is used when operating in the IPSTEALTH
1227  * mode to tell what options to process:
1228  * [LS]SRR (pass 0) or the others (pass 1).
1229  * The reason for as many as two passes is that when doing IPSTEALTH,
1230  * non-routing options should be processed only if the packet is for us.
1231  * Returns 1 if packet has been forwarded/freed,
1232  * 0 if the packet should be processed further.
1233  */
1234 static int
1235 ip_dooptions(struct mbuf *m, int pass)
1236 {
1237         struct ip *ip = mtod(m, struct ip *);
1238         u_char *cp;
1239         struct in_ifaddr *ia;
1240         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1241         struct in_addr *sin, dst;
1242         n_time ntime;
1243         struct  sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
1244
1245         /* ignore or reject packets with IP options */
1246         if (ip_doopts == 0)
1247                 return 0;
1248         else if (ip_doopts == 2) {
1249                 type = ICMP_UNREACH;
1250                 code = ICMP_UNREACH_FILTER_PROHIB;
1251                 goto bad;
1252         }
1253
1254         dst = ip->ip_dst;
1255         cp = (u_char *)(ip + 1);
1256         cnt = (ip->ip_hl << 2) - sizeof (struct ip);
1257         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1258                 opt = cp[IPOPT_OPTVAL];
1259                 if (opt == IPOPT_EOL)
1260                         break;
1261                 if (opt == IPOPT_NOP)
1262                         optlen = 1;
1263                 else {
1264                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
1265                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1266                                 goto bad;
1267                         }
1268                         optlen = cp[IPOPT_OLEN];
1269                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
1270                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1271                                 goto bad;
1272                         }
1273                 }
1274                 switch (opt) {
1275
1276                 default:
1277                         break;
1278
1279                 /*
1280                  * Source routing with record.
1281                  * Find interface with current destination address.
1282                  * If none on this machine then drop if strictly routed,
1283                  * or do nothing if loosely routed.
1284                  * Record interface address and bring up next address
1285                  * component.  If strictly routed make sure next
1286                  * address is on directly accessible net.
1287                  */
1288                 case IPOPT_LSRR:
1289                 case IPOPT_SSRR:
1290 #ifdef IPSTEALTH
1291                         if (ipstealth && pass > 0)
1292                                 break;
1293 #endif
1294                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1295                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1296                                 goto bad;
1297                         }
1298                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1299                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1300                                 goto bad;
1301                         }
1302                         ipaddr.sin_addr = ip->ip_dst;
1303                         ia = (struct in_ifaddr *)
1304                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
1305                         if (ia == NULL) {
1306                                 if (opt == IPOPT_SSRR) {
1307                                         type = ICMP_UNREACH;
1308                                         code = ICMP_UNREACH_SRCFAIL;
1309                                         goto bad;
1310                                 }
1311                                 if (!ip_dosourceroute)
1312                                         goto nosourcerouting;
1313                                 /*
1314                                  * Loose routing, and not at next destination
1315                                  * yet; nothing to do except forward.
1316                                  */
1317                                 break;
1318                         }
1319                         off--;                  /* 0 origin */
1320                         if (off > optlen - (int)sizeof(struct in_addr)) {
1321                                 /*
1322                                  * End of source route.  Should be for us.
1323                                  */
1324                                 if (!ip_acceptsourceroute)
1325                                         goto nosourcerouting;
1326                                 save_rte(m, cp, ip->ip_src);
1327                                 break;
1328                         }
1329 #ifdef IPSTEALTH
1330                         if (ipstealth)
1331                                 goto dropit;
1332 #endif
1333                         if (!ip_dosourceroute) {
1334                                 if (ipforwarding) {
1335                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
1336                                         /*
1337                                          * Acting as a router, so generate ICMP
1338                                          */
1339 nosourcerouting:
1340                                         strcpy(buf, inet_ntoa(ip->ip_dst));
1341                                         log(LOG_WARNING,
1342                                             "attempted source route from %s to %s\n",
1343                                             inet_ntoa(ip->ip_src), buf);
1344                                         type = ICMP_UNREACH;
1345                                         code = ICMP_UNREACH_SRCFAIL;
1346                                         goto bad;
1347                                 } else {
1348                                         /*
1349                                          * Not acting as a router, so silently drop.
1350                                          */
1351 #ifdef IPSTEALTH
1352 dropit:
1353 #endif
1354                                         ipstat.ips_cantforward++;
1355                                         m_freem(m);
1356                                         return (1);
1357                                 }
1358                         }
1359
1360                         /*
1361                          * locate outgoing interface
1362                          */
1363                         (void)memcpy(&ipaddr.sin_addr, cp + off,
1364                             sizeof(ipaddr.sin_addr));
1365
1366                         if (opt == IPOPT_SSRR) {
1367 #define INA     struct in_ifaddr *
1368 #define SA      struct sockaddr *
1369                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
1370                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1371                         } else
1372                                 ia = ip_rtaddr(ipaddr.sin_addr);
1373                         if (ia == NULL) {
1374                                 type = ICMP_UNREACH;
1375                                 code = ICMP_UNREACH_SRCFAIL;
1376                                 goto bad;
1377                         }
1378                         ip->ip_dst = ipaddr.sin_addr;
1379                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1380                             sizeof(struct in_addr));
1381                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1382                         /*
1383                          * Let ip_intr's mcast routing check handle mcast pkts
1384                          */
1385                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
1386                         break;
1387
1388                 case IPOPT_RR:
1389 #ifdef IPSTEALTH
1390                         if (ipstealth && pass == 0)
1391                                 break;
1392 #endif
1393                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1394                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1395                                 goto bad;
1396                         }
1397                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1398                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1399                                 goto bad;
1400                         }
1401                         /*
1402                          * If no space remains, ignore.
1403                          */
1404                         off--;                  /* 0 origin */
1405                         if (off > optlen - (int)sizeof(struct in_addr))
1406                                 break;
1407                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
1408                             sizeof(ipaddr.sin_addr));
1409                         /*
1410                          * locate outgoing interface; if we're the destination,
1411                          * use the incoming interface (should be same).
1412                          */
1413                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
1414                             (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
1415                                 type = ICMP_UNREACH;
1416                                 code = ICMP_UNREACH_HOST;
1417                                 goto bad;
1418                         }
1419                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1420                             sizeof(struct in_addr));
1421                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1422                         break;
1423
1424                 case IPOPT_TS:
1425 #ifdef IPSTEALTH
1426                         if (ipstealth && pass == 0)
1427                                 break;
1428 #endif
1429                         code = cp - (u_char *)ip;
1430                         if (optlen < 4 || optlen > 40) {
1431                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1432                                 goto bad;
1433                         }
1434                         if ((off = cp[IPOPT_OFFSET]) < 5) {
1435                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1436                                 goto bad;
1437                         }
1438                         if (off > optlen - (int)sizeof(int32_t)) {
1439                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
1440                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
1441                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1442                                         goto bad;
1443                                 }
1444                                 break;
1445                         }
1446                         off--;                          /* 0 origin */
1447                         sin = (struct in_addr *)(cp + off);
1448                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
1449
1450                         case IPOPT_TS_TSONLY:
1451                                 break;
1452
1453                         case IPOPT_TS_TSANDADDR:
1454                                 if (off + sizeof(n_time) +
1455                                     sizeof(struct in_addr) > optlen) {
1456                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1457                                         goto bad;
1458                                 }
1459                                 ipaddr.sin_addr = dst;
1460                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
1461                                                             m->m_pkthdr.rcvif);
1462                                 if (ia == NULL)
1463                                         continue;
1464                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
1465                                     sizeof(struct in_addr));
1466                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1467                                 off += sizeof(struct in_addr);
1468                                 break;
1469
1470                         case IPOPT_TS_PRESPEC:
1471                                 if (off + sizeof(n_time) +
1472                                     sizeof(struct in_addr) > optlen) {
1473                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1474                                         goto bad;
1475                                 }
1476                                 (void)memcpy(&ipaddr.sin_addr, sin,
1477                                     sizeof(struct in_addr));
1478                                 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
1479                                         continue;
1480                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1481                                 off += sizeof(struct in_addr);
1482                                 break;
1483
1484                         default:
1485                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
1486                                 goto bad;
1487                         }
1488                         ntime = iptime();
1489                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
1490                         cp[IPOPT_OFFSET] += sizeof(n_time);
1491                 }
1492         }
1493         if (forward && ipforwarding) {
1494                 ip_forward(m, 1);
1495                 return (1);
1496         }
1497         return (0);
1498 bad:
1499         icmp_error(m, type, code, 0, 0);
1500         ipstat.ips_badoptions++;
1501         return (1);
1502 }
1503
1504 /*
1505  * Given address of next destination (final or next hop),
1506  * return internet address info of interface to be used to get there.
1507  */
1508 struct in_ifaddr *
1509 ip_rtaddr(dst)
1510         struct in_addr dst;
1511 {
1512         struct route sro;
1513         struct sockaddr_in *sin;
1514         struct in_ifaddr *ifa;
1515
1516         bzero(&sro, sizeof(sro));
1517         sin = (struct sockaddr_in *)&sro.ro_dst;
1518         sin->sin_family = AF_INET;
1519         sin->sin_len = sizeof(*sin);
1520         sin->sin_addr = dst;
1521         rtalloc_ign(&sro, RTF_CLONING);
1522
1523         if (sro.ro_rt == NULL)
1524                 return (NULL);
1525
1526         ifa = ifatoia(sro.ro_rt->rt_ifa);
1527         RTFREE(sro.ro_rt);
1528         return (ifa);
1529 }
1530
1531 /*
1532  * Save incoming source route for use in replies,
1533  * to be picked up later by ip_srcroute if the receiver is interested.
1534  */
1535 static void
1536 save_rte(m, option, dst)
1537         struct mbuf *m;
1538         u_char *option;
1539         struct in_addr dst;
1540 {
1541         unsigned olen;
1542         struct ipopt_tag *opts;
1543
1544         opts = (struct ipopt_tag *)m_tag_get(PACKET_TAG_IPOPTIONS,
1545                                         sizeof(struct ipopt_tag), M_NOWAIT);
1546         if (opts == NULL)
1547                 return;
1548
1549         olen = option[IPOPT_OLEN];
1550 #ifdef DIAGNOSTIC
1551         if (ipprintfs)
1552                 printf("save_rte: olen %d\n", olen);
1553 #endif
1554         if (olen > sizeof(opts->ip_srcrt) - (1 + sizeof(dst)))
1555                 return;
1556         bcopy(option, opts->ip_srcrt.srcopt, olen);
1557         opts->ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1558         opts->ip_srcrt.dst = dst;
1559         m_tag_prepend(m, (struct m_tag *)opts);
1560 }
1561
1562 /*
1563  * Retrieve incoming source route for use in replies,
1564  * in the same form used by setsockopt.
1565  * The first hop is placed before the options, will be removed later.
1566  */
1567 struct mbuf *
1568 ip_srcroute(m0)
1569         struct mbuf *m0;
1570 {
1571         register struct in_addr *p, *q;
1572         register struct mbuf *m;
1573         struct ipopt_tag *opts;
1574
1575         opts = (struct ipopt_tag *)m_tag_find(m0, PACKET_TAG_IPOPTIONS, NULL);
1576         if (opts == NULL)
1577                 return (NULL);
1578
1579         if (opts->ip_nhops == 0)
1580                 return (NULL);
1581         m = m_get(M_DONTWAIT, MT_HEADER);
1582         if (m == NULL)
1583                 return (NULL);
1584
1585 #define OPTSIZ  (sizeof(opts->ip_srcrt.nop) + sizeof(opts->ip_srcrt.srcopt))
1586
1587         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1588         m->m_len = opts->ip_nhops * sizeof(struct in_addr) +
1589             sizeof(struct in_addr) + OPTSIZ;
1590 #ifdef DIAGNOSTIC
1591         if (ipprintfs)
1592                 printf("ip_srcroute: nhops %d mlen %d", opts->ip_nhops, m->m_len);
1593 #endif
1594
1595         /*
1596          * First save first hop for return route
1597          */
1598         p = &(opts->ip_srcrt.route[opts->ip_nhops - 1]);
1599         *(mtod(m, struct in_addr *)) = *p--;
1600 #ifdef DIAGNOSTIC
1601         if (ipprintfs)
1602                 printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr));
1603 #endif
1604
1605         /*
1606          * Copy option fields and padding (nop) to mbuf.
1607          */
1608         opts->ip_srcrt.nop = IPOPT_NOP;
1609         opts->ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1610         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
1611             &(opts->ip_srcrt.nop), OPTSIZ);
1612         q = (struct in_addr *)(mtod(m, caddr_t) +
1613             sizeof(struct in_addr) + OPTSIZ);
1614 #undef OPTSIZ
1615         /*
1616          * Record return path as an IP source route,
1617          * reversing the path (pointers are now aligned).
1618          */
1619         while (p >= opts->ip_srcrt.route) {
1620 #ifdef DIAGNOSTIC
1621                 if (ipprintfs)
1622                         printf(" %lx", (u_long)ntohl(q->s_addr));
1623 #endif
1624                 *q++ = *p--;
1625         }
1626         /*
1627          * Last hop goes to final destination.
1628          */
1629         *q = opts->ip_srcrt.dst;
1630 #ifdef DIAGNOSTIC
1631         if (ipprintfs)
1632                 printf(" %lx\n", (u_long)ntohl(q->s_addr));
1633 #endif
1634         m_tag_delete(m0, (struct m_tag *)opts);
1635         return (m);
1636 }
1637
1638 /*
1639  * Strip out IP options, at higher
1640  * level protocol in the kernel.
1641  * Second argument is buffer to which options
1642  * will be moved, and return value is their length.
1643  * XXX should be deleted; last arg currently ignored.
1644  */
1645 void
1646 ip_stripoptions(m, mopt)
1647         register struct mbuf *m;
1648         struct mbuf *mopt;
1649 {
1650         register int i;
1651         struct ip *ip = mtod(m, struct ip *);
1652         register caddr_t opts;
1653         int olen;
1654
1655         olen = (ip->ip_hl << 2) - sizeof (struct ip);
1656         opts = (caddr_t)(ip + 1);
1657         i = m->m_len - (sizeof (struct ip) + olen);
1658         bcopy(opts + olen, opts, (unsigned)i);
1659         m->m_len -= olen;
1660         if (m->m_flags & M_PKTHDR)
1661                 m->m_pkthdr.len -= olen;
1662         ip->ip_v = IPVERSION;
1663         ip->ip_hl = sizeof(struct ip) >> 2;
1664 }
1665
1666 u_char inetctlerrmap[PRC_NCMDS] = {
1667         0,              0,              0,              0,
1668         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
1669         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
1670         EMSGSIZE,       EHOSTUNREACH,   0,              0,
1671         0,              0,              EHOSTUNREACH,   0,
1672         ENOPROTOOPT,    ECONNREFUSED
1673 };
1674
1675 /*
1676  * Forward a packet.  If some error occurs return the sender
1677  * an icmp packet.  Note we can't always generate a meaningful
1678  * icmp message because icmp doesn't have a large enough repertoire
1679  * of codes and types.
1680  *
1681  * If not forwarding, just drop the packet.  This could be confusing
1682  * if ipforwarding was zero but some routing protocol was advancing
1683  * us as a gateway to somewhere.  However, we must let the routing
1684  * protocol deal with that.
1685  *
1686  * The srcrt parameter indicates whether the packet is being forwarded
1687  * via a source route.
1688  */
1689 void
1690 ip_forward(struct mbuf *m, int srcrt)
1691 {
1692         struct ip *ip = mtod(m, struct ip *);
1693         struct in_ifaddr *ia = NULL;
1694         int error, type = 0, code = 0;
1695         struct mbuf *mcopy;
1696         struct in_addr dest;
1697         struct ifnet *destifp, dummyifp;
1698
1699 #ifdef DIAGNOSTIC
1700         if (ipprintfs)
1701                 printf("forward: src %lx dst %lx ttl %x\n",
1702                     (u_long)ip->ip_src.s_addr, (u_long)ip->ip_dst.s_addr,
1703                     ip->ip_ttl);
1704 #endif
1705
1706
1707         if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
1708                 ipstat.ips_cantforward++;
1709                 m_freem(m);
1710                 return;
1711         }
1712 #ifdef IPSTEALTH
1713         if (!ipstealth) {
1714 #endif
1715                 if (ip->ip_ttl <= IPTTLDEC) {
1716                         icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
1717                             0, 0);
1718                         return;
1719                 }
1720 #ifdef IPSTEALTH
1721         }
1722 #endif
1723
1724         if (!srcrt && (ia = ip_rtaddr(ip->ip_dst)) == NULL) {
1725                 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
1726                 return;
1727         }
1728
1729         /*
1730          * Save the IP header and at most 8 bytes of the payload,
1731          * in case we need to generate an ICMP message to the src.
1732          *
1733          * XXX this can be optimized a lot by saving the data in a local
1734          * buffer on the stack (72 bytes at most), and only allocating the
1735          * mbuf if really necessary. The vast majority of the packets
1736          * are forwarded without having to send an ICMP back (either
1737          * because unnecessary, or because rate limited), so we are
1738          * really we are wasting a lot of work here.
1739          *
1740          * We don't use m_copy() because it might return a reference
1741          * to a shared cluster. Both this function and ip_output()
1742          * assume exclusive access to the IP header in `m', so any
1743          * data in a cluster may change before we reach icmp_error().
1744          */
1745         MGET(mcopy, M_DONTWAIT, m->m_type);
1746         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
1747                 /*
1748                  * It's probably ok if the pkthdr dup fails (because
1749                  * the deep copy of the tag chain failed), but for now
1750                  * be conservative and just discard the copy since
1751                  * code below may some day want the tags.
1752                  */
1753                 m_free(mcopy);
1754                 mcopy = NULL;
1755         }
1756         if (mcopy != NULL) {
1757                 mcopy->m_len = imin((ip->ip_hl << 2) + 8,
1758                     (int)ip->ip_len);
1759                 mcopy->m_pkthdr.len = mcopy->m_len;
1760                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
1761         }
1762
1763 #ifdef IPSTEALTH
1764         if (!ipstealth) {
1765 #endif
1766                 ip->ip_ttl -= IPTTLDEC;
1767 #ifdef IPSTEALTH
1768         }
1769 #endif
1770
1771         /*
1772          * If forwarding packet using same interface that it came in on,
1773          * perhaps should send a redirect to sender to shortcut a hop.
1774          * Only send redirect if source is sending directly to us,
1775          * and if packet was not source routed (or has any options).
1776          * Also, don't send redirect if forwarding using a default route
1777          * or a route modified by a redirect.
1778          */
1779         dest.s_addr = 0;
1780         if (!srcrt && ipsendredirects && ia->ia_ifp == m->m_pkthdr.rcvif) {
1781                 struct sockaddr_in *sin;
1782                 struct route ro;
1783                 struct rtentry *rt;
1784
1785                 bzero(&ro, sizeof(ro));
1786                 sin = (struct sockaddr_in *)&ro.ro_dst;
1787                 sin->sin_family = AF_INET;
1788                 sin->sin_len = sizeof(*sin);
1789                 sin->sin_addr = ip->ip_dst;
1790                 rtalloc_ign(&ro, RTF_CLONING);
1791
1792                 rt = ro.ro_rt;
1793
1794                 if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1795                     satosin(rt_key(rt))->sin_addr.s_addr != 0) {
1796 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1797                         u_long src = ntohl(ip->ip_src.s_addr);
1798
1799                         if (RTA(rt) &&
1800                             (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1801                                 if (rt->rt_flags & RTF_GATEWAY)
1802                                         dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr;
1803                                 else
1804                                         dest.s_addr = ip->ip_dst.s_addr;
1805                                 /* Router requirements says to only send host redirects */
1806                                 type = ICMP_REDIRECT;
1807                                 code = ICMP_REDIRECT_HOST;
1808 #ifdef DIAGNOSTIC
1809                                 if (ipprintfs)
1810                                         printf("redirect (%d) to %lx\n", code, (u_long)dest.s_addr);
1811 #endif
1812                         }
1813                 }
1814                 if (rt)
1815                         RTFREE(rt);
1816         }
1817
1818         error = ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
1819         if (error)
1820                 ipstat.ips_cantforward++;
1821         else {
1822                 ipstat.ips_forward++;
1823                 if (type)
1824                         ipstat.ips_redirectsent++;
1825                 else {
1826                         if (mcopy)
1827                                 m_freem(mcopy);
1828                         return;
1829                 }
1830         }
1831         if (mcopy == NULL)
1832                 return;
1833         destifp = NULL;
1834
1835         switch (error) {
1836
1837         case 0:                         /* forwarded, but need redirect */
1838                 /* type, code set above */
1839                 break;
1840
1841         case ENETUNREACH:               /* shouldn't happen, checked above */
1842         case EHOSTUNREACH:
1843         case ENETDOWN:
1844         case EHOSTDOWN:
1845         default:
1846                 type = ICMP_UNREACH;
1847                 code = ICMP_UNREACH_HOST;
1848                 break;
1849
1850         case EMSGSIZE:
1851                 type = ICMP_UNREACH;
1852                 code = ICMP_UNREACH_NEEDFRAG;
1853 #if defined(IPSEC) || defined(FAST_IPSEC)
1854                 /*
1855                  * If the packet is routed over IPsec tunnel, tell the
1856                  * originator the tunnel MTU.
1857                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1858                  * XXX quickhack!!!
1859                  */
1860                 {
1861                         struct secpolicy *sp = NULL;
1862                         int ipsecerror;
1863                         int ipsechdr;
1864                         struct route *ro;
1865
1866 #ifdef IPSEC
1867                         sp = ipsec4_getpolicybyaddr(mcopy,
1868                                                     IPSEC_DIR_OUTBOUND,
1869                                                     IP_FORWARDING,
1870                                                     &ipsecerror);
1871 #else /* FAST_IPSEC */
1872                         sp = ipsec_getpolicybyaddr(mcopy,
1873                                                    IPSEC_DIR_OUTBOUND,
1874                                                    IP_FORWARDING,
1875                                                    &ipsecerror);
1876 #endif
1877                         if (sp != NULL) {
1878                                 /* count IPsec header size */
1879                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1880                                                          IPSEC_DIR_OUTBOUND,
1881                                                          NULL);
1882
1883                                 /*
1884                                  * find the correct route for outer IPv4
1885                                  * header, compute tunnel MTU.
1886                                  *
1887                                  * XXX BUG ALERT
1888                                  * The "dummyifp" code relies upon the fact
1889                                  * that icmp_error() touches only ifp->if_mtu.
1890                                  */
1891                                 /*XXX*/
1892                                 destifp = NULL;
1893                                 if (sp->req != NULL
1894                                  && sp->req->sav != NULL
1895                                  && sp->req->sav->sah != NULL) {
1896                                         ro = &sp->req->sav->sah->sa_route;
1897                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1898                                                 dummyifp.if_mtu =
1899                                                     ro->ro_rt->rt_rmx.rmx_mtu ?
1900                                                     ro->ro_rt->rt_rmx.rmx_mtu :
1901                                                     ro->ro_rt->rt_ifp->if_mtu;
1902                                                 dummyifp.if_mtu -= ipsechdr;
1903                                                 destifp = &dummyifp;
1904                                         }
1905                                 }
1906
1907 #ifdef IPSEC
1908                                 key_freesp(sp);
1909 #else /* FAST_IPSEC */
1910                                 KEY_FREESP(&sp);
1911 #endif
1912                                 ipstat.ips_cantfrag++;
1913                                 break;
1914                         } else
1915 #endif /*IPSEC || FAST_IPSEC*/
1916                 /*
1917                  * When doing source routing 'ia' can be NULL.  Fall back
1918                  * to the minimum guaranteed routeable packet size and use
1919                  * the same hack as IPSEC to setup a dummyifp for icmp.
1920                  */
1921                 if (ia == NULL) {
1922                         dummyifp.if_mtu = IP_MSS;
1923                         destifp = &dummyifp;
1924                 } else
1925                         destifp = ia->ia_ifp;
1926 #if defined(IPSEC) || defined(FAST_IPSEC)
1927                 }
1928 #endif /*IPSEC || FAST_IPSEC*/
1929                 ipstat.ips_cantfrag++;
1930                 break;
1931
1932         case ENOBUFS:
1933                 /*
1934                  * A router should not generate ICMP_SOURCEQUENCH as
1935                  * required in RFC1812 Requirements for IP Version 4 Routers.
1936                  * Source quench could be a big problem under DoS attacks,
1937                  * or if the underlying interface is rate-limited.
1938                  * Those who need source quench packets may re-enable them
1939                  * via the net.inet.ip.sendsourcequench sysctl.
1940                  */
1941                 if (ip_sendsourcequench == 0) {
1942                         m_freem(mcopy);
1943                         return;
1944                 } else {
1945                         type = ICMP_SOURCEQUENCH;
1946                         code = 0;
1947                 }
1948                 break;
1949
1950         case EACCES:                    /* ipfw denied packet */
1951                 m_freem(mcopy);
1952                 return;
1953         }
1954         icmp_error(mcopy, type, code, dest.s_addr, destifp);
1955 }
1956
1957 void
1958 ip_savecontrol(inp, mp, ip, m)
1959         register struct inpcb *inp;
1960         register struct mbuf **mp;
1961         register struct ip *ip;
1962         register struct mbuf *m;
1963 {
1964         if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) {
1965                 struct bintime bt;
1966
1967                 bintime(&bt);
1968                 if (inp->inp_socket->so_options & SO_BINTIME) {
1969                         *mp = sbcreatecontrol((caddr_t) &bt, sizeof(bt),
1970                         SCM_BINTIME, SOL_SOCKET);
1971                         if (*mp)
1972                                 mp = &(*mp)->m_next;
1973                 }
1974                 if (inp->inp_socket->so_options & SO_TIMESTAMP) {
1975                         struct timeval tv;
1976
1977                         bintime2timeval(&bt, &tv);
1978                         *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
1979                                 SCM_TIMESTAMP, SOL_SOCKET);
1980                         if (*mp)
1981                                 mp = &(*mp)->m_next;
1982                 }
1983         }
1984         if (inp->inp_flags & INP_RECVDSTADDR) {
1985                 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
1986                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
1987                 if (*mp)
1988                         mp = &(*mp)->m_next;
1989         }
1990         if (inp->inp_flags & INP_RECVTTL) {
1991                 *mp = sbcreatecontrol((caddr_t) &ip->ip_ttl,
1992                     sizeof(u_char), IP_RECVTTL, IPPROTO_IP);
1993                 if (*mp)
1994                         mp = &(*mp)->m_next;
1995         }
1996 #ifdef notyet
1997         /* XXX
1998          * Moving these out of udp_input() made them even more broken
1999          * than they already were.
2000          */
2001         /* options were tossed already */
2002         if (inp->inp_flags & INP_RECVOPTS) {
2003                 *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
2004                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
2005                 if (*mp)
2006                         mp = &(*mp)->m_next;
2007         }
2008         /* ip_srcroute doesn't do what we want here, need to fix */
2009         if (inp->inp_flags & INP_RECVRETOPTS) {
2010                 *mp = sbcreatecontrol((caddr_t) ip_srcroute(m),
2011                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
2012                 if (*mp)
2013                         mp = &(*mp)->m_next;
2014         }
2015 #endif
2016         if (inp->inp_flags & INP_RECVIF) {
2017                 struct ifnet *ifp;
2018                 struct sdlbuf {
2019                         struct sockaddr_dl sdl;
2020                         u_char  pad[32];
2021                 } sdlbuf;
2022                 struct sockaddr_dl *sdp;
2023                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
2024
2025                 if (((ifp = m->m_pkthdr.rcvif))
2026                 && ( ifp->if_index && (ifp->if_index <= if_index))) {
2027                         sdp = (struct sockaddr_dl *)
2028                             (ifaddr_byindex(ifp->if_index)->ifa_addr);
2029                         /*
2030                          * Change our mind and don't try copy.
2031                          */
2032                         if ((sdp->sdl_family != AF_LINK)
2033                         || (sdp->sdl_len > sizeof(sdlbuf))) {
2034                                 goto makedummy;
2035                         }
2036                         bcopy(sdp, sdl2, sdp->sdl_len);
2037                 } else {
2038 makedummy:
2039                         sdl2->sdl_len
2040                                 = offsetof(struct sockaddr_dl, sdl_data[0]);
2041                         sdl2->sdl_family = AF_LINK;
2042                         sdl2->sdl_index = 0;
2043                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
2044                 }
2045                 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
2046                         IP_RECVIF, IPPROTO_IP);
2047                 if (*mp)
2048                         mp = &(*mp)->m_next;
2049         }
2050 }
2051
2052 /*
2053  * XXX these routines are called from the upper part of the kernel.
2054  * They need to be locked when we remove Giant.
2055  *
2056  * They could also be moved to ip_mroute.c, since all the RSVP
2057  *  handling is done there already.
2058  */
2059 static int ip_rsvp_on;
2060 struct socket *ip_rsvpd;
2061 int
2062 ip_rsvp_init(struct socket *so)
2063 {
2064         if (so->so_type != SOCK_RAW ||
2065             so->so_proto->pr_protocol != IPPROTO_RSVP)
2066                 return EOPNOTSUPP;
2067
2068         if (ip_rsvpd != NULL)
2069                 return EADDRINUSE;
2070
2071         ip_rsvpd = so;
2072         /*
2073          * This may seem silly, but we need to be sure we don't over-increment
2074          * the RSVP counter, in case something slips up.
2075          */
2076         if (!ip_rsvp_on) {
2077                 ip_rsvp_on = 1;
2078                 rsvp_on++;
2079         }
2080
2081         return 0;
2082 }
2083
2084 int
2085 ip_rsvp_done(void)
2086 {
2087         ip_rsvpd = NULL;
2088         /*
2089          * This may seem silly, but we need to be sure we don't over-decrement
2090          * the RSVP counter, in case something slips up.
2091          */
2092         if (ip_rsvp_on) {
2093                 ip_rsvp_on = 0;
2094                 rsvp_on--;
2095         }
2096         return 0;
2097 }
2098
2099 void
2100 rsvp_input(struct mbuf *m, int off)     /* XXX must fixup manually */
2101 {
2102         if (rsvp_input_p) { /* call the real one if loaded */
2103                 rsvp_input_p(m, off);
2104                 return;
2105         }
2106
2107         /* Can still get packets with rsvp_on = 0 if there is a local member
2108          * of the group to which the RSVP packet is addressed.  But in this
2109          * case we want to throw the packet away.
2110          */
2111
2112         if (!rsvp_on) {
2113                 m_freem(m);
2114                 return;
2115         }
2116
2117         if (ip_rsvpd != NULL) {
2118                 rip_input(m, off);
2119                 return;
2120         }
2121         /* Drop the packet */
2122         m_freem(m);
2123 }