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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
  34  * $FreeBSD: src/sys/netinet/ip_input.c,v 1.130.2.52 2003/03/07 07:01:28 silby Exp $
  35  * $DragonFly: src/sys/netinet/ip_input.c,v 1.8 2003/11/08 07:57:51 dillon Exp $
  36  */
  37
  38 #define _IP_VHL
  39
  40 #include "opt_bootp.h"
  41 #include "opt_ipfw.h"
  42 #include "opt_ipdn.h"
  43 #include "opt_ipdivert.h"
  44 #include "opt_ipfilter.h"
  45 #include "opt_ipstealth.h"
  46 #include "opt_ipsec.h"
  47 #include "opt_random_ip_id.h"
  48
  49 #include <sys/param.h>
  50 #include <sys/systm.h>
  51 #include <sys/mbuf.h>
  52 #include <sys/malloc.h>
  53 #include <sys/domain.h>
  54 #include <sys/protosw.h>
  55 #include <sys/socket.h>
  56 #include <sys/time.h>
  57 #include <sys/kernel.h>
  58 #include <sys/syslog.h>
  59 #include <sys/sysctl.h>
  60
  61 #include <net/if.h>
  62 #include <net/if_types.h>
  63 #include <net/if_var.h>
  64 #include <net/if_dl.h>
  65 #include <net/route.h>
  66 #include <net/netisr.h>
  67 #include <net/intrq.h>
  68
  69 #include <netinet/in.h>
  70 #include <netinet/in_systm.h>
  71 #include <netinet/in_var.h>
  72 #include <netinet/ip.h>
  73 #include <netinet/in_pcb.h>
  74 #include <netinet/ip_var.h>
  75 #include <netinet/ip_icmp.h>
  76 #include <machine/in_cksum.h>
  77
  78 #include <netinet/ipprotosw.h>
  79
  80 #include <sys/socketvar.h>
  81
  82 #include <net/ipfw/ip_fw.h>
  83 #include <net/dummynet/ip_dummynet.h>
  84
  85 #ifdef IPSEC
  86 #include <netinet6/ipsec.h>
  87 #include <netproto/key/key.h>
  88 #endif
  89
  90 #ifdef FAST_IPSEC
  91 #include <netipsec/ipsec.h>
  92 #include <netipsec/key.h>
  93 #endif
  94
  95 int rsvp_on = 0;
  96 static int ip_rsvp_on;
  97 struct socket *ip_rsvpd;
  98
  99 int     ipforwarding = 0;
 100 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
 101     &ipforwarding, 0, "Enable IP forwarding between interfaces");
 102
 103 static int      ipsendredirects = 1; /* XXX */
 104 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
 105     &ipsendredirects, 0, "Enable sending IP redirects");
 106
 107 int     ip_defttl = IPDEFTTL;
 108 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
 109     &ip_defttl, 0, "Maximum TTL on IP packets");
 110
 111 static int      ip_dosourceroute = 0;
 112 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
 113     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
 114
 115 static int      ip_acceptsourceroute = 0;
 116 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
 117     CTLFLAG_RW, &ip_acceptsourceroute, 0,
 118     "Enable accepting source routed IP packets");
 119
 120 static int      ip_keepfaith = 0;
 121 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
 122         &ip_keepfaith,  0,
 123         "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
 124
 125 static int      nipq = 0;       /* total # of reass queues */
 126 static int      maxnipq;
 127 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
 128         &maxnipq, 0,
 129         "Maximum number of IPv4 fragment reassembly queue entries");
 130
 131 static int    maxfragsperpacket;
 132 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
 133         &maxfragsperpacket, 0,
 134         "Maximum number of IPv4 fragments allowed per packet");
 135
 136 static int      ip_sendsourcequench = 0;
 137 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
 138         &ip_sendsourcequench, 0,
 139         "Enable the transmission of source quench packets");
 140
 141 /*
 142  * XXX - Setting ip_checkinterface mostly implements the receive side of
 143  * the Strong ES model described in RFC 1122, but since the routing table
 144  * and transmit implementation do not implement the Strong ES model,
 145  * setting this to 1 results in an odd hybrid.
 146  *
 147  * XXX - ip_checkinterface currently must be disabled if you use ipnat
 148  * to translate the destination address to another local interface.
 149  *
 150  * XXX - ip_checkinterface must be disabled if you add IP aliases
 151  * to the loopback interface instead of the interface where the
 152  * packets for those addresses are received.
 153  */
 154 static int      ip_checkinterface = 0;
 155 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
 156     &ip_checkinterface, 0, "Verify packet arrives on correct interface");
 157
 158 #ifdef DIAGNOSTIC
 159 static int      ipprintfs = 0;
 160 #endif
 161
 162 static struct ifqueue ipintrq;
 163 static int      ipqmaxlen = IFQ_MAXLEN;
 164
 165 extern  struct domain inetdomain;
 166 extern  struct ipprotosw 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 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
 172     &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
 173 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
 174     &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
 175
 176 struct ipstat ipstat;
 177 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
 178     &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)");
 179
 180 /* Packet reassembly stuff */
 181 #define IPREASS_NHASH_LOG2      6
 182 #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
 183 #define IPREASS_HMASK           (IPREASS_NHASH - 1)
 184 #define IPREASS_HASH(x,y) \
 185         (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
 186
 187 static struct ipq ipq[IPREASS_NHASH];
 188 const  int    ipintrq_present = 1;
 189
 190 #ifdef IPCTL_DEFMTU
 191 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
 192     &ip_mtu, 0, "Default MTU");
 193 #endif
 194
 195 #ifdef IPSTEALTH
 196 static int      ipstealth = 0;
 197 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
 198     &ipstealth, 0, "");
 199 #endif
 200
 201
 202 /* Firewall hooks */
 203 ip_fw_chk_t *ip_fw_chk_ptr;
 204 int fw_enable = 1 ;
 205 int fw_one_pass = 1;
 206
 207 /* Dummynet hooks */
 208 ip_dn_io_t *ip_dn_io_ptr;
 209
 210 int (*fr_checkp) (struct ip *, int, struct ifnet *, int, struct mbuf **) = NULL;
 211
 212 /*
 213  * XXX this is ugly -- the following two global variables are
 214  * used to store packet state while it travels through the stack.
 215  * Note that the code even makes assumptions on the size and
 216  * alignment of fields inside struct ip_srcrt so e.g. adding some
 217  * fields will break the code. This needs to be fixed.
 218  *
 219  * We need to save the IP options in case a protocol wants to respond
 220  * to an incoming packet over the same route if the packet got here
 221  * using IP source routing.  This allows connection establishment and
 222  * maintenance when the remote end is on a network that is not known
 223  * to us.
 224  */
 225 static int      ip_nhops = 0;
 226 static  struct ip_srcrt {
 227         struct  in_addr dst;                    /* final destination */
 228         char    nop;                            /* one NOP to align */
 229         char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
 230         struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
 231 } ip_srcrt;
 232
 233 static void     save_rte(u_char *, struct in_addr);
 234 static int      ip_dooptions(struct mbuf *m, int,
 235                         struct sockaddr_in *next_hop);
 236 static void     ip_forward(struct mbuf *m, int srcrt,
 237                         struct sockaddr_in *next_hop);
 238 static void     ip_freef(struct ipq *);
 239 static struct   mbuf *ip_reass(struct mbuf *, struct ipq *,
 240                 struct ipq *, u_int32_t *, u_int16_t *);
 241
 242 /*
 243  * IP initialization: fill in IP protocol switch table.
 244  * All protocols not implemented in kernel go to raw IP protocol handler.
 245  */
 246 void
 247 ip_init()
 248 {
 249         struct ipprotosw *pr;
 250         int i;
 251
 252         TAILQ_INIT(&in_ifaddrhead);
 253         in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask);
 254         pr = (struct ipprotosw *)pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 255         if (pr == 0)
 256                 panic("ip_init");
 257         for (i = 0; i < IPPROTO_MAX; i++)
 258                 ip_protox[i] = pr - inetsw;
 259         for (pr = (struct ipprotosw *)inetdomain.dom_protosw;
 260             pr < (struct ipprotosw *)inetdomain.dom_protoswNPROTOSW; pr++)
 261                 if (pr->pr_domain->dom_family == PF_INET &&
 262                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
 263                         ip_protox[pr->pr_protocol] = pr - inetsw;
 264
 265         for (i = 0; i < IPREASS_NHASH; i++)
 266             ipq[i].next = ipq[i].prev = &ipq[i];
 267
 268         maxnipq = nmbclusters / 32;
 269         maxfragsperpacket = 16;
 270
 271 #ifndef RANDOM_IP_ID
 272         ip_id = time_second & 0xffff;
 273 #endif
 274         ipintrq.ifq_maxlen = ipqmaxlen;
 275
 276         netisr_register(NETISR_IP, ip_mport, ip_input);
 277 }
 278
 279 /*
 280  * XXX watch out this one. It is perhaps used as a cache for
 281  * the most recently used route ? it is cleared in in_addroute()
 282  * when a new route is successfully created.
 283  */
 284 struct  route ipforward_rt;
 285 static struct   sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
 286
 287 /*
 288  * Ip input routine.  Checksum and byte swap header.  If fragmented
 289  * try to reassemble.  Process options.  Pass to next level.
 290  */
 291 void
 292 ip_input(struct mbuf *m)
 293 {
 294         struct ip *ip;
 295         struct ipq *fp;
 296         struct in_ifaddr *ia = NULL;
 297         struct ifaddr *ifa;
 298         int    i, hlen, checkif;
 299         u_short sum;
 300         struct in_addr pkt_dst;
 301         u_int32_t divert_info = 0;              /* packet divert/tee info */
 302         struct ip_fw_args args;
 303 #ifdef FAST_IPSEC
 304         struct m_tag *mtag;
 305         struct tdb_ident *tdbi;
 306         struct secpolicy *sp;
 307         int s, error;
 308 #endif /* FAST_IPSEC */
 309
 310         args.eh = NULL;
 311         args.oif = NULL;
 312         args.rule = NULL;
 313         args.divert_rule = 0;                   /* divert cookie */
 314         args.next_hop = NULL;
 315
 316         /* Grab info from MT_TAG mbufs prepended to the chain.  */
 317         for (; m && m->m_type == MT_TAG; m = m->m_next) {
 318                 switch(m->_m_tag_id) {
 319                 default:
 320                         printf("ip_input: unrecognised MT_TAG tag %d\n",
 321                             m->_m_tag_id);
 322                         break;
 323
 324                 case PACKET_TAG_DUMMYNET:
 325                         args.rule = ((struct dn_pkt *)m)->rule;
 326                         break;
 327
 328                 case PACKET_TAG_DIVERT:
 329                         args.divert_rule = (int)m->m_hdr.mh_data & 0xffff;
 330                         break;
 331
 332                 case PACKET_TAG_IPFORWARD:
 333                         args.next_hop = (struct sockaddr_in *)m->m_hdr.mh_data;
 334                         break;
 335                 }
 336         }
 337
 338         KASSERT(m != NULL && (m->m_flags & M_PKTHDR) != 0,
 339             ("ip_input: no HDR"));
 340
 341         if (args.rule) {        /* dummynet already filtered us */
 342                 ip = mtod(m, struct ip *);
 343                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 344                 goto iphack ;
 345         }
 346
 347         ipstat.ips_total++;
 348
 349         if (m->m_pkthdr.len < sizeof(struct ip))
 350                 goto tooshort;
 351
 352         if (m->m_len < sizeof (struct ip) &&
 353             (m = m_pullup(m, sizeof (struct ip))) == 0) {
 354                 ipstat.ips_toosmall++;
 355                 return;
 356         }
 357         ip = mtod(m, struct ip *);
 358
 359         if (IP_VHL_V(ip->ip_vhl) != IPVERSION) {
 360                 ipstat.ips_badvers++;
 361                 goto bad;
 362         }
 363
 364         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 365         if (hlen < sizeof(struct ip)) { /* minimum header length */
 366                 ipstat.ips_badhlen++;
 367                 goto bad;
 368         }
 369         if (hlen > m->m_len) {
 370                 if ((m = m_pullup(m, hlen)) == 0) {
 371                         ipstat.ips_badhlen++;
 372                         return;
 373                 }
 374                 ip = mtod(m, struct ip *);
 375         }
 376
 377         /* 127/8 must not appear on wire - RFC1122 */
 378         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
 379             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
 380                 if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
 381                         ipstat.ips_badaddr++;
 382                         goto bad;
 383                 }
 384         }
 385
 386         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
 387                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
 388         } else {
 389                 if (hlen == sizeof(struct ip)) {
 390                         sum = in_cksum_hdr(ip);
 391                 } else {
 392                         sum = in_cksum(m, hlen);
 393                 }
 394         }
 395         if (sum) {
 396                 ipstat.ips_badsum++;
 397                 goto bad;
 398         }
 399
 400         /*
 401          * Convert fields to host representation.
 402          */
 403         ip->ip_len = ntohs(ip->ip_len);
 404         if (ip->ip_len < hlen) {
 405                 ipstat.ips_badlen++;
 406                 goto bad;
 407         }
 408         ip->ip_off = ntohs(ip->ip_off);
 409
 410         /*
 411          * Check that the amount of data in the buffers
 412          * is as at least much as the IP header would have us expect.
 413          * Trim mbufs if longer than we expect.
 414          * Drop packet if shorter than we expect.
 415          */
 416         if (m->m_pkthdr.len < ip->ip_len) {
 417 tooshort:
 418                 ipstat.ips_tooshort++;
 419                 goto bad;
 420         }
 421         if (m->m_pkthdr.len > ip->ip_len) {
 422                 if (m->m_len == m->m_pkthdr.len) {
 423                         m->m_len = ip->ip_len;
 424                         m->m_pkthdr.len = ip->ip_len;
 425                 } else
 426                         m_adj(m, ip->ip_len - m->m_pkthdr.len);
 427         }
 428 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
 429         /*
 430          * Bypass packet filtering for packets from a tunnel (gif).
 431          */
 432         if (ipsec_gethist(m, NULL))
 433                 goto pass;
 434 #endif
 435
 436         /*
 437          * IpHack's section.
 438          * Right now when no processing on packet has done
 439          * and it is still fresh out of network we do our black
 440          * deals with it.
 441          * - Firewall: deny/allow/divert
 442          * - Xlate: translate packet's addr/port (NAT).
 443          * - Pipe: pass pkt through dummynet.
 444          * - Wrap: fake packet's addr/port <unimpl.>
 445          * - Encapsulate: put it in another IP and send out. <unimp.>
 446          */
 447
 448 iphack:
 449         /*
 450          * Check if we want to allow this packet to be processed.
 451          * Consider it to be bad if not.
 452          */
 453         if (fr_checkp) {
 454                 struct  mbuf    *m1 = m;
 455
 456                 if ((*fr_checkp)(ip, hlen, m->m_pkthdr.rcvif, 0, &m1) || !m1)
 457                         return;
 458                 ip = mtod(m = m1, struct ip *);
 459         }
 460         if (fw_enable && IPFW_LOADED) {
 461                 /*
 462                  * If we've been forwarded from the output side, then
 463                  * skip the firewall a second time
 464                  */
 465                 if (args.next_hop)
 466                         goto ours;
 467
 468                 args.m = m;
 469                 i = ip_fw_chk_ptr(&args);
 470                 m = args.m;
 471
 472                 if ( (i & IP_FW_PORT_DENY_FLAG) || m == NULL) { /* drop */
 473                         if (m)
 474                                 m_freem(m);
 475                         return;
 476                 }
 477                 ip = mtod(m, struct ip *); /* just in case m changed */
 478                 if (i == 0 && args.next_hop == NULL)    /* common case */
 479                         goto pass;
 480                 if (DUMMYNET_LOADED && (i & IP_FW_PORT_DYNT_FLAG) != 0) {
 481                         /* Send packet to the appropriate pipe */
 482                         ip_dn_io_ptr(m, i&0xffff, DN_TO_IP_IN, &args);
 483                         return;
 484                 }
 485 #ifdef IPDIVERT
 486                 if (i != 0 && (i & IP_FW_PORT_DYNT_FLAG) == 0) {
 487                         /* Divert or tee packet */
 488                         divert_info = i;
 489                         goto ours;
 490                 }
 491 #endif
 492                 if (i == 0 && args.next_hop != NULL)
 493                         goto pass;
 494                 /*
 495                  * if we get here, the packet must be dropped
 496                  */
 497                 m_freem(m);
 498                 return;
 499         }
 500 pass:
 501
 502         /*
 503          * Process options and, if not destined for us,
 504          * ship it on.  ip_dooptions returns 1 when an
 505          * error was detected (causing an icmp message
 506          * to be sent and the original packet to be freed).
 507          */
 508         ip_nhops = 0;           /* for source routed packets */
 509         if (hlen > sizeof (struct ip) && ip_dooptions(m, 0, args.next_hop))
 510                 return;
 511
 512         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
 513          * matter if it is destined to another node, or whether it is
 514          * a multicast one, RSVP wants it! and prevents it from being forwarded
 515          * anywhere else. Also checks if the rsvp daemon is running before
 516          * grabbing the packet.
 517          */
 518         if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
 519                 goto ours;
 520
 521         /*
 522          * Check our list of addresses, to see if the packet is for us.
 523          * If we don't have any addresses, assume any unicast packet
 524          * we receive might be for us (and let the upper layers deal
 525          * with it).
 526          */
 527         if (TAILQ_EMPTY(&in_ifaddrhead) &&
 528             (m->m_flags & (M_MCAST|M_BCAST)) == 0)
 529                 goto ours;
 530
 531         /*
 532          * Cache the destination address of the packet; this may be
 533          * changed by use of 'ipfw fwd'.
 534          */
 535         pkt_dst = args.next_hop ? args.next_hop->sin_addr : ip->ip_dst;
 536
 537         /*
 538          * Enable a consistency check between the destination address
 539          * and the arrival interface for a unicast packet (the RFC 1122
 540          * strong ES model) if IP forwarding is disabled and the packet
 541          * is not locally generated and the packet is not subject to
 542          * 'ipfw fwd'.
 543          *
 544          * XXX - Checking also should be disabled if the destination
 545          * address is ipnat'ed to a different interface.
 546          *
 547          * XXX - Checking is incompatible with IP aliases added
 548          * to the loopback interface instead of the interface where
 549          * the packets are received.
 550          */
 551         checkif = ip_checkinterface && (ipforwarding == 0) &&
 552             m->m_pkthdr.rcvif != NULL &&
 553             ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) &&
 554             (args.next_hop == NULL);
 555
 556         /*
 557          * Check for exact addresses in the hash bucket.
 558          */
 559         LIST_FOREACH(ia, INADDR_HASH(pkt_dst.s_addr), ia_hash) {
 560                 /*
 561                  * If the address matches, verify that the packet
 562                  * arrived via the correct interface if checking is
 563                  * enabled.
 564                  */
 565                 if (IA_SIN(ia)->sin_addr.s_addr == pkt_dst.s_addr &&
 566                     (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
 567                         goto ours;
 568         }
 569         /*
 570          * Check for broadcast addresses.
 571          *
 572          * Only accept broadcast packets that arrive via the matching
 573          * interface.  Reception of forwarded directed broadcasts would
 574          * be handled via ip_forward() and ether_output() with the loopback
 575          * into the stack for SIMPLEX interfaces handled by ether_output().
 576          */
 577         if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
 578                 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
 579                         if (ifa->ifa_addr->sa_family != AF_INET)
 580                                 continue;
 581                         ia = ifatoia(ifa);
 582                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 583                             pkt_dst.s_addr)
 584                                 goto ours;
 585                         if (ia->ia_netbroadcast.s_addr == pkt_dst.s_addr)
 586                                 goto ours;
 587 #ifdef BOOTP_COMPAT
 588                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
 589                                 goto ours;
 590 #endif
 591                 }
 592         }
 593         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
 594                 struct in_multi *inm;
 595                 if (ip_mrouter) {
 596                         /*
 597                          * If we are acting as a multicast router, all
 598                          * incoming multicast packets are passed to the
 599                          * kernel-level multicast forwarding function.
 600                          * The packet is returned (relatively) intact; if
 601                          * ip_mforward() returns a non-zero value, the packet
 602                          * must be discarded, else it may be accepted below.
 603                          */
 604                         if (ip_mforward &&
 605                             ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
 606                                 ipstat.ips_cantforward++;
 607                                 m_freem(m);
 608                                 return;
 609                         }
 610
 611                         /*
 612                          * The process-level routing daemon needs to receive
 613                          * all multicast IGMP packets, whether or not this
 614                          * host belongs to their destination groups.
 615                          */
 616                         if (ip->ip_p == IPPROTO_IGMP)
 617                                 goto ours;
 618                         ipstat.ips_forward++;
 619                 }
 620                 /*
 621                  * See if we belong to the destination multicast group on the
 622                  * arrival interface.
 623                  */
 624                 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
 625                 if (inm == NULL) {
 626                         ipstat.ips_notmember++;
 627                         m_freem(m);
 628                         return;
 629                 }
 630                 goto ours;
 631         }
 632         if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
 633                 goto ours;
 634         if (ip->ip_dst.s_addr == INADDR_ANY)
 635                 goto ours;
 636
 637         /*
 638          * FAITH(Firewall Aided Internet Translator)
 639          */
 640         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 641                 if (ip_keepfaith) {
 642                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
 643                                 goto ours;
 644                 }
 645                 m_freem(m);
 646                 return;
 647         }
 648
 649         /*
 650          * Not for us; forward if possible and desirable.
 651          */
 652         if (ipforwarding == 0) {
 653                 ipstat.ips_cantforward++;
 654                 m_freem(m);
 655         } else {
 656 #ifdef IPSEC
 657                 /*
 658                  * Enforce inbound IPsec SPD.
 659                  */
 660                 if (ipsec4_in_reject(m, NULL)) {
 661                         ipsecstat.in_polvio++;
 662                         goto bad;
 663                 }
 664 #endif /* IPSEC */
 665 #ifdef FAST_IPSEC
 666                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 667                 s = splnet();
 668                 if (mtag != NULL) {
 669                         tdbi = (struct tdb_ident *)(mtag + 1);
 670                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 671                 } else {
 672                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 673                                                    IP_FORWARDING, &error);
 674                 }
 675                 if (sp == NULL) {       /* NB: can happen if error */
 676                         splx(s);
 677                         /*XXX error stat???*/
 678                         DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 679                         goto bad;
 680                 }
 681
 682                 /*
 683                  * Check security policy against packet attributes.
 684                  */
 685                 error = ipsec_in_reject(sp, m);
 686                 KEY_FREESP(&sp);
 687                 splx(s);
 688                 if (error) {
 689                         ipstat.ips_cantforward++;
 690                         goto bad;
 691                 }
 692 #endif /* FAST_IPSEC */
 693                 ip_forward(m, 0, args.next_hop);
 694         }
 695         return;
 696
 697 ours:
 698 #ifdef IPSTEALTH
 699         /*
 700          * IPSTEALTH: Process non-routing options only
 701          * if the packet is destined for us.
 702          */
 703         if (ipstealth && hlen > sizeof (struct ip) &&
 704             ip_dooptions(m, 1, args.next_hop))
 705                 return;
 706 #endif /* IPSTEALTH */
 707
 708         /* Count the packet in the ip address stats */
 709         if (ia != NULL) {
 710                 ia->ia_ifa.if_ipackets++;
 711                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
 712         }
 713
 714         /*
 715          * If offset or IP_MF are set, must reassemble.
 716          * Otherwise, nothing need be done.
 717          * (We could look in the reassembly queue to see
 718          * if the packet was previously fragmented,
 719          * but it's not worth the time; just let them time out.)
 720          */
 721         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 722
 723                 /* If maxnipq is 0, never accept fragments. */
 724                 if (maxnipq == 0) {
 725                         ipstat.ips_fragments++;
 726                         ipstat.ips_fragdropped++;
 727                         goto bad;
 728                 }
 729
 730                 sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
 731                 /*
 732                  * Look for queue of fragments
 733                  * of this datagram.
 734                  */
 735                 for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next)
 736                         if (ip->ip_id == fp->ipq_id &&
 737                             ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 738                             ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 739                             ip->ip_p == fp->ipq_p)
 740                                 goto found;
 741
 742                 fp = 0;
 743
 744                 /*
 745                  * Enforce upper bound on number of fragmented packets
 746                  * for which we attempt reassembly;
 747                  * If maxnipq is -1, accept all fragments without limitation.
 748                  */
 749                 if ((nipq > maxnipq) && (maxnipq > 0)) {
 750                     /*
 751                      * drop something from the tail of the current queue
 752                      * before proceeding further
 753                      */
 754                     if (ipq[sum].prev == &ipq[sum]) {   /* gak */
 755                         for (i = 0; i < IPREASS_NHASH; i++) {
 756                             if (ipq[i].prev != &ipq[i]) {
 757                                 ipstat.ips_fragtimeout +=
 758                                     ipq[i].prev->ipq_nfrags;
 759                                 ip_freef(ipq[i].prev);
 760                                 break;
 761                             }
 762                         }
 763                     } else {
 764                         ipstat.ips_fragtimeout += ipq[sum].prev->ipq_nfrags;
 765                         ip_freef(ipq[sum].prev);
 766                     }
 767                 }
 768 found:
 769                 /*
 770                  * Adjust ip_len to not reflect header,
 771                  * convert offset of this to bytes.
 772                  */
 773                 ip->ip_len -= hlen;
 774                 if (ip->ip_off & IP_MF) {
 775                         /*
 776                          * Make sure that fragments have a data length
 777                          * that's a non-zero multiple of 8 bytes.
 778                          */
 779                         if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
 780                                 ipstat.ips_toosmall++; /* XXX */
 781                                 goto bad;
 782                         }
 783                         m->m_flags |= M_FRAG;
 784                 } else
 785                         m->m_flags &= ~M_FRAG;
 786                 ip->ip_off <<= 3;
 787
 788                 /*
 789                  * Attempt reassembly; if it succeeds, proceed.
 790                  * ip_reass() will return a different mbuf, and update
 791                  * the divert info in divert_info and args.divert_rule.
 792                  */
 793                 ipstat.ips_fragments++;
 794                 m->m_pkthdr.header = ip;
 795                 m = ip_reass(m,
 796                     fp, &ipq[sum], &divert_info, &args.divert_rule);
 797                 if (m == 0)
 798                         return;
 799                 ipstat.ips_reassembled++;
 800                 ip = mtod(m, struct ip *);
 801                 /* Get the header length of the reassembled packet */
 802                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 803 #ifdef IPDIVERT
 804                 /* Restore original checksum before diverting packet */
 805                 if (divert_info != 0) {
 806                         ip->ip_len += hlen;
 807                         ip->ip_len = htons(ip->ip_len);
 808                         ip->ip_off = htons(ip->ip_off);
 809                         ip->ip_sum = 0;
 810                         if (hlen == sizeof(struct ip))
 811                                 ip->ip_sum = in_cksum_hdr(ip);
 812                         else
 813                                 ip->ip_sum = in_cksum(m, hlen);
 814                         ip->ip_off = ntohs(ip->ip_off);
 815                         ip->ip_len = ntohs(ip->ip_len);
 816                         ip->ip_len -= hlen;
 817                 }
 818 #endif
 819         } else {
 820                 ip->ip_len -= hlen;
 821         }
 822
 823 #ifdef IPDIVERT
 824         /*
 825          * Divert or tee packet to the divert protocol if required.
 826          */
 827         if (divert_info != 0) {
 828                 struct mbuf *clone = NULL;
 829
 830                 /* Clone packet if we're doing a 'tee' */
 831                 if ((divert_info & IP_FW_PORT_TEE_FLAG) != 0)
 832                         clone = m_dup(m, M_DONTWAIT);
 833
 834                 /* Restore packet header fields to original values */
 835                 ip->ip_len += hlen;
 836                 ip->ip_len = htons(ip->ip_len);
 837                 ip->ip_off = htons(ip->ip_off);
 838
 839                 /* Deliver packet to divert input routine */
 840                 divert_packet(m, 1, divert_info & 0xffff, args.divert_rule);
 841                 ipstat.ips_delivered++;
 842
 843                 /* If 'tee', continue with original packet */
 844                 if (clone == NULL)
 845                         return;
 846                 m = clone;
 847                 ip = mtod(m, struct ip *);
 848                 ip->ip_len += hlen;
 849                 /*
 850                  * Jump backwards to complete processing of the
 851                  * packet. But first clear divert_info to avoid
 852                  * entering this block again.
 853                  * We do not need to clear args.divert_rule
 854                  * or args.next_hop as they will not be used.
 855                  */
 856                 divert_info = 0;
 857                 goto pass;
 858         }
 859 #endif
 860
 861 #ifdef IPSEC
 862         /*
 863          * enforce IPsec policy checking if we are seeing last header.
 864          * note that we do not visit this with protocols with pcb layer
 865          * code - like udp/tcp/raw ip.
 866          */
 867         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
 868             ipsec4_in_reject(m, NULL)) {
 869                 ipsecstat.in_polvio++;
 870                 goto bad;
 871         }
 872 #endif
 873 #if FAST_IPSEC
 874         /*
 875          * enforce IPsec policy checking if we are seeing last header.
 876          * note that we do not visit this with protocols with pcb layer
 877          * code - like udp/tcp/raw ip.
 878          */
 879         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 880                 /*
 881                  * Check if the packet has already had IPsec processing
 882                  * done.  If so, then just pass it along.  This tag gets
 883                  * set during AH, ESP, etc. input handling, before the
 884                  * packet is returned to the ip input queue for delivery.
 885                  */
 886                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 887                 s = splnet();
 888                 if (mtag != NULL) {
 889                         tdbi = (struct tdb_ident *)(mtag + 1);
 890                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 891                 } else {
 892                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 893                                                    IP_FORWARDING, &error);
 894                 }
 895                 if (sp != NULL) {
 896                         /*
 897                          * Check security policy against packet attributes.
 898                          */
 899                         error = ipsec_in_reject(sp, m);
 900                         KEY_FREESP(&sp);
 901                 } else {
 902                         /* XXX error stat??? */
 903                         error = EINVAL;
 904 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 905                         goto bad;
 906                 }
 907                 splx(s);
 908                 if (error)
 909                         goto bad;
 910         }
 911 #endif /* FAST_IPSEC */
 912
 913         /*
 914          * Switch out to protocol's input routine.
 915          *
 916          * XXX queue packet to protocol's message port.
 917          */
 918         ipstat.ips_delivered++;
 919         if (args.next_hop && ip->ip_p == IPPROTO_TCP) {
 920                 /* TCP needs IPFORWARD info if available */
 921                 struct m_hdr tag;
 922
 923                 tag.mh_type = MT_TAG;
 924                 tag.mh_flags = PACKET_TAG_IPFORWARD;
 925                 tag.mh_data = (caddr_t)args.next_hop;
 926                 tag.mh_next = m;
 927
 928                 (*inetsw[ip_protox[ip->ip_p]].pr_input)(
 929                         (struct mbuf *)&tag, hlen, ip->ip_p);
 930         } else {
 931                 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen, ip->ip_p);
 932         }
 933         return;
 934 bad:
 935         m_freem(m);
 936 }
 937
 938 /*
 939  * Take incoming datagram fragment and try to reassemble it into
 940  * whole datagram.  If a chain for reassembly of this datagram already
 941  * exists, then it is given as fp; otherwise have to make a chain.
 942  *
 943  * When IPDIVERT enabled, keep additional state with each packet that
 944  * tells us if we need to divert or tee the packet we're building.
 945  * In particular, *divinfo includes the port and TEE flag,
 946  * *divert_rule is the number of the matching rule.
 947  */
 948
 949 static struct mbuf *
 950 ip_reass(struct mbuf *m, struct ipq *fp, struct ipq *where,
 951         u_int32_t *divinfo, u_int16_t *divert_rule)
 952 {
 953         struct ip *ip = mtod(m, struct ip *);
 954         struct mbuf *p = 0, *q, *nq;
 955         struct mbuf *t;
 956         int hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 957         int i, next;
 958
 959         /*
 960          * Presence of header sizes in mbufs
 961          * would confuse code below.
 962          */
 963         m->m_data += hlen;
 964         m->m_len -= hlen;
 965
 966         /*
 967          * If first fragment to arrive, create a reassembly queue.
 968          */
 969         if (fp == 0) {
 970                 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
 971                         goto dropfrag;
 972                 fp = mtod(t, struct ipq *);
 973                 insque(fp, where);
 974                 nipq++;
 975                 fp->ipq_nfrags = 1;
 976                 fp->ipq_ttl = IPFRAGTTL;
 977                 fp->ipq_p = ip->ip_p;
 978                 fp->ipq_id = ip->ip_id;
 979                 fp->ipq_src = ip->ip_src;
 980                 fp->ipq_dst = ip->ip_dst;
 981                 fp->ipq_frags = m;
 982                 m->m_nextpkt = NULL;
 983 #ifdef IPDIVERT
 984                 fp->ipq_div_info = 0;
 985                 fp->ipq_div_cookie = 0;
 986 #endif
 987                 goto inserted;
 988         } else {
 989                 fp->ipq_nfrags++;
 990         }
 991
 992 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.header))
 993
 994         /*
 995          * Find a segment which begins after this one does.
 996          */
 997         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
 998                 if (GETIP(q)->ip_off > ip->ip_off)
 999                         break;
1000
1001         /*
1002          * If there is a preceding segment, it may provide some of
1003          * our data already.  If so, drop the data from the incoming
1004          * segment.  If it provides all of our data, drop us, otherwise
1005          * stick new segment in the proper place.
1006          *
1007          * If some of the data is dropped from the the preceding
1008          * segment, then it's checksum is invalidated.
1009          */
1010         if (p) {
1011                 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
1012                 if (i > 0) {
1013                         if (i >= ip->ip_len)
1014                                 goto dropfrag;
1015                         m_adj(m, i);
1016                         m->m_pkthdr.csum_flags = 0;
1017                         ip->ip_off += i;
1018                         ip->ip_len -= i;
1019                 }
1020                 m->m_nextpkt = p->m_nextpkt;
1021                 p->m_nextpkt = m;
1022         } else {
1023                 m->m_nextpkt = fp->ipq_frags;
1024                 fp->ipq_frags = m;
1025         }
1026
1027         /*
1028          * While we overlap succeeding segments trim them or,
1029          * if they are completely covered, dequeue them.
1030          */
1031         for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
1032              q = nq) {
1033                 i = (ip->ip_off + ip->ip_len) -
1034                     GETIP(q)->ip_off;
1035                 if (i < GETIP(q)->ip_len) {
1036                         GETIP(q)->ip_len -= i;
1037                         GETIP(q)->ip_off += i;
1038                         m_adj(q, i);
1039                         q->m_pkthdr.csum_flags = 0;
1040                         break;
1041                 }
1042                 nq = q->m_nextpkt;
1043                 m->m_nextpkt = nq;
1044                 ipstat.ips_fragdropped++;
1045                 fp->ipq_nfrags--;
1046                 m_freem(q);
1047         }
1048
1049 inserted:
1050
1051 #ifdef IPDIVERT
1052         /*
1053          * Transfer firewall instructions to the fragment structure.
1054          * Only trust info in the fragment at offset 0.
1055          */
1056         if (ip->ip_off == 0) {
1057                 fp->ipq_div_info = *divinfo;
1058                 fp->ipq_div_cookie = *divert_rule;
1059         }
1060         *divinfo = 0;
1061         *divert_rule = 0;
1062 #endif
1063
1064         /*
1065          * Check for complete reassembly and perform frag per packet
1066          * limiting.
1067          *
1068          * Frag limiting is performed here so that the nth frag has
1069          * a chance to complete the packet before we drop the packet.
1070          * As a result, n+1 frags are actually allowed per packet, but
1071          * only n will ever be stored. (n = maxfragsperpacket.)
1072          *
1073          */
1074         next = 0;
1075         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
1076                 if (GETIP(q)->ip_off != next) {
1077                         if (fp->ipq_nfrags > maxfragsperpacket) {
1078                                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1079                                 ip_freef(fp);
1080                         }
1081                         return (0);
1082                 }
1083                 next += GETIP(q)->ip_len;
1084         }
1085         /* Make sure the last packet didn't have the IP_MF flag */
1086         if (p->m_flags & M_FRAG) {
1087                 if (fp->ipq_nfrags > maxfragsperpacket) {
1088                         ipstat.ips_fragdropped += fp->ipq_nfrags;
1089                         ip_freef(fp);
1090                 }
1091                 return (0);
1092         }
1093
1094         /*
1095          * Reassembly is complete.  Make sure the packet is a sane size.
1096          */
1097         q = fp->ipq_frags;
1098         ip = GETIP(q);
1099         if (next + (IP_VHL_HL(ip->ip_vhl) << 2) > IP_MAXPACKET) {
1100                 ipstat.ips_toolong++;
1101                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1102                 ip_freef(fp);
1103                 return (0);
1104         }
1105
1106         /*
1107          * Concatenate fragments.
1108          */
1109         m = q;
1110         t = m->m_next;
1111         m->m_next = 0;
1112         m_cat(m, t);
1113         nq = q->m_nextpkt;
1114         q->m_nextpkt = 0;
1115         for (q = nq; q != NULL; q = nq) {
1116                 nq = q->m_nextpkt;
1117                 q->m_nextpkt = NULL;
1118                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
1119                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
1120                 m_cat(m, q);
1121         }
1122
1123 #ifdef IPDIVERT
1124         /*
1125          * Extract firewall instructions from the fragment structure.
1126          */
1127         *divinfo = fp->ipq_div_info;
1128         *divert_rule = fp->ipq_div_cookie;
1129 #endif
1130
1131         /*
1132          * Create header for new ip packet by
1133          * modifying header of first packet;
1134          * dequeue and discard fragment reassembly header.
1135          * Make header visible.
1136          */
1137         ip->ip_len = next;
1138         ip->ip_src = fp->ipq_src;
1139         ip->ip_dst = fp->ipq_dst;
1140         remque(fp);
1141         nipq--;
1142         (void) m_free(dtom(fp));
1143         m->m_len += (IP_VHL_HL(ip->ip_vhl) << 2);
1144         m->m_data -= (IP_VHL_HL(ip->ip_vhl) << 2);
1145         /* some debugging cruft by sklower, below, will go away soon */
1146         if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
1147                 int plen = 0;
1148                 for (t = m; t; t = t->m_next)
1149                         plen += t->m_len;
1150                 m->m_pkthdr.len = plen;
1151         }
1152         return (m);
1153
1154 dropfrag:
1155 #ifdef IPDIVERT
1156         *divinfo = 0;
1157         *divert_rule = 0;
1158 #endif
1159         ipstat.ips_fragdropped++;
1160         if (fp != 0)
1161                 fp->ipq_nfrags--;
1162         m_freem(m);
1163         return (0);
1164
1165 #undef GETIP
1166 }
1167
1168 /*
1169  * Free a fragment reassembly header and all
1170  * associated datagrams.
1171  */
1172 static void
1173 ip_freef(fp)
1174         struct ipq *fp;
1175 {
1176         struct mbuf *q;
1177
1178         while (fp->ipq_frags) {
1179                 q = fp->ipq_frags;
1180                 fp->ipq_frags = q->m_nextpkt;
1181                 m_freem(q);
1182         }
1183         remque(fp);
1184         (void) m_free(dtom(fp));
1185         nipq--;
1186 }
1187
1188 /*
1189  * IP timer processing;
1190  * if a timer expires on a reassembly
1191  * queue, discard it.
1192  */
1193 void
1194 ip_slowtimo()
1195 {
1196         struct ipq *fp;
1197         int s = splnet();
1198         int i;
1199
1200         for (i = 0; i < IPREASS_NHASH; i++) {
1201                 fp = ipq[i].next;
1202                 if (fp == 0)
1203                         continue;
1204                 while (fp != &ipq[i]) {
1205                         --fp->ipq_ttl;
1206                         fp = fp->next;
1207                         if (fp->prev->ipq_ttl == 0) {
1208                                 ipstat.ips_fragtimeout += fp->prev->ipq_nfrags;
1209                                 ip_freef(fp->prev);
1210                         }
1211                 }
1212         }
1213         /*
1214          * If we are over the maximum number of fragments
1215          * (due to the limit being lowered), drain off
1216          * enough to get down to the new limit.
1217          */
1218         if (maxnipq >= 0 && nipq > maxnipq) {
1219                 for (i = 0; i < IPREASS_NHASH; i++) {
1220                         while (nipq > maxnipq &&
1221                                 (ipq[i].next != &ipq[i])) {
1222                                 ipstat.ips_fragdropped +=
1223                                     ipq[i].next->ipq_nfrags;
1224                                 ip_freef(ipq[i].next);
1225                         }
1226                 }
1227         }
1228         ipflow_slowtimo();
1229         splx(s);
1230 }
1231
1232 /*
1233  * Drain off all datagram fragments.
1234  */
1235 void
1236 ip_drain()
1237 {
1238         int     i;
1239
1240         for (i = 0; i < IPREASS_NHASH; i++) {
1241                 while (ipq[i].next != &ipq[i]) {
1242                         ipstat.ips_fragdropped += ipq[i].next->ipq_nfrags;
1243                         ip_freef(ipq[i].next);
1244                 }
1245         }
1246         in_rtqdrain();
1247 }
1248
1249 /*
1250  * Do option processing on a datagram,
1251  * possibly discarding it if bad options are encountered,
1252  * or forwarding it if source-routed.
1253  * The pass argument is used when operating in the IPSTEALTH
1254  * mode to tell what options to process:
1255  * [LS]SRR (pass 0) or the others (pass 1).
1256  * The reason for as many as two passes is that when doing IPSTEALTH,
1257  * non-routing options should be processed only if the packet is for us.
1258  * Returns 1 if packet has been forwarded/freed,
1259  * 0 if the packet should be processed further.
1260  */
1261 static int
1262 ip_dooptions(struct mbuf *m, int pass, struct sockaddr_in *next_hop)
1263 {
1264         struct ip *ip = mtod(m, struct ip *);
1265         u_char *cp;
1266         struct in_ifaddr *ia;
1267         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1268         struct in_addr *sin, dst;
1269         n_time ntime;
1270
1271         dst = ip->ip_dst;
1272         cp = (u_char *)(ip + 1);
1273         cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
1274         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1275                 opt = cp[IPOPT_OPTVAL];
1276                 if (opt == IPOPT_EOL)
1277                         break;
1278                 if (opt == IPOPT_NOP)
1279                         optlen = 1;
1280                 else {
1281                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
1282                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1283                                 goto bad;
1284                         }
1285                         optlen = cp[IPOPT_OLEN];
1286                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
1287                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1288                                 goto bad;
1289                         }
1290                 }
1291                 switch (opt) {
1292
1293                 default:
1294                         break;
1295
1296                 /*
1297                  * Source routing with record.
1298                  * Find interface with current destination address.
1299                  * If none on this machine then drop if strictly routed,
1300                  * or do nothing if loosely routed.
1301                  * Record interface address and bring up next address
1302                  * component.  If strictly routed make sure next
1303                  * address is on directly accessible net.
1304                  */
1305                 case IPOPT_LSRR:
1306                 case IPOPT_SSRR:
1307 #ifdef IPSTEALTH
1308                         if (ipstealth && pass > 0)
1309                                 break;
1310 #endif
1311                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1312                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1313                                 goto bad;
1314                         }
1315                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1316                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1317                                 goto bad;
1318                         }
1319                         ipaddr.sin_addr = ip->ip_dst;
1320                         ia = (struct in_ifaddr *)
1321                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
1322                         if (ia == 0) {
1323                                 if (opt == IPOPT_SSRR) {
1324                                         type = ICMP_UNREACH;
1325                                         code = ICMP_UNREACH_SRCFAIL;
1326                                         goto bad;
1327                                 }
1328                                 if (!ip_dosourceroute)
1329                                         goto nosourcerouting;
1330                                 /*
1331                                  * Loose routing, and not at next destination
1332                                  * yet; nothing to do except forward.
1333                                  */
1334                                 break;
1335                         }
1336                         off--;                  /* 0 origin */
1337                         if (off > optlen - (int)sizeof(struct in_addr)) {
1338                                 /*
1339                                  * End of source route.  Should be for us.
1340                                  */
1341                                 if (!ip_acceptsourceroute)
1342                                         goto nosourcerouting;
1343                                 save_rte(cp, ip->ip_src);
1344                                 break;
1345                         }
1346 #ifdef IPSTEALTH
1347                         if (ipstealth)
1348                                 goto dropit;
1349 #endif
1350                         if (!ip_dosourceroute) {
1351                                 if (ipforwarding) {
1352                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
1353                                         /*
1354                                          * Acting as a router, so generate ICMP
1355                                          */
1356 nosourcerouting:
1357                                         strcpy(buf, inet_ntoa(ip->ip_dst));
1358                                         log(LOG_WARNING,
1359                                             "attempted source route from %s to %s\n",
1360                                             inet_ntoa(ip->ip_src), buf);
1361                                         type = ICMP_UNREACH;
1362                                         code = ICMP_UNREACH_SRCFAIL;
1363                                         goto bad;
1364                                 } else {
1365                                         /*
1366                                          * Not acting as a router, so silently drop.
1367                                          */
1368 #ifdef IPSTEALTH
1369 dropit:
1370 #endif
1371                                         ipstat.ips_cantforward++;
1372                                         m_freem(m);
1373                                         return (1);
1374                                 }
1375                         }
1376
1377                         /*
1378                          * locate outgoing interface
1379                          */
1380                         (void)memcpy(&ipaddr.sin_addr, cp + off,
1381                             sizeof(ipaddr.sin_addr));
1382
1383                         if (opt == IPOPT_SSRR) {
1384 #define INA     struct in_ifaddr *
1385 #define SA      struct sockaddr *
1386                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
1387                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1388                         } else
1389                                 ia = ip_rtaddr(ipaddr.sin_addr, &ipforward_rt);
1390                         if (ia == 0) {
1391                                 type = ICMP_UNREACH;
1392                                 code = ICMP_UNREACH_SRCFAIL;
1393                                 goto bad;
1394                         }
1395                         ip->ip_dst = ipaddr.sin_addr;
1396                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1397                             sizeof(struct in_addr));
1398                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1399                         /*
1400                          * Let ip_intr's mcast routing check handle mcast pkts
1401                          */
1402                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
1403                         break;
1404
1405                 case IPOPT_RR:
1406 #ifdef IPSTEALTH
1407                         if (ipstealth && pass == 0)
1408                                 break;
1409 #endif
1410                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1411                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1412                                 goto bad;
1413                         }
1414                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1415                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1416                                 goto bad;
1417                         }
1418                         /*
1419                          * If no space remains, ignore.
1420                          */
1421                         off--;                  /* 0 origin */
1422                         if (off > optlen - (int)sizeof(struct in_addr))
1423                                 break;
1424                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
1425                             sizeof(ipaddr.sin_addr));
1426                         /*
1427                          * locate outgoing interface; if we're the destination,
1428                          * use the incoming interface (should be same).
1429                          */
1430                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
1431                             (ia = ip_rtaddr(ipaddr.sin_addr,
1432                             &ipforward_rt)) == 0) {
1433                                 type = ICMP_UNREACH;
1434                                 code = ICMP_UNREACH_HOST;
1435                                 goto bad;
1436                         }
1437                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1438                             sizeof(struct in_addr));
1439                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1440                         break;
1441
1442                 case IPOPT_TS:
1443 #ifdef IPSTEALTH
1444                         if (ipstealth && pass == 0)
1445                                 break;
1446 #endif
1447                         code = cp - (u_char *)ip;
1448                         if (optlen < 4 || optlen > 40) {
1449                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1450                                 goto bad;
1451                         }
1452                         if ((off = cp[IPOPT_OFFSET]) < 5) {
1453                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1454                                 goto bad;
1455                         }
1456                         if (off > optlen - (int)sizeof(int32_t)) {
1457                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
1458                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
1459                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1460                                         goto bad;
1461                                 }
1462                                 break;
1463                         }
1464                         off--;                          /* 0 origin */
1465                         sin = (struct in_addr *)(cp + off);
1466                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
1467
1468                         case IPOPT_TS_TSONLY:
1469                                 break;
1470
1471                         case IPOPT_TS_TSANDADDR:
1472                                 if (off + sizeof(n_time) +
1473                                     sizeof(struct in_addr) > optlen) {
1474                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1475                                         goto bad;
1476                                 }
1477                                 ipaddr.sin_addr = dst;
1478                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
1479                                                             m->m_pkthdr.rcvif);
1480                                 if (ia == 0)
1481                                         continue;
1482                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
1483                                     sizeof(struct in_addr));
1484                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1485                                 off += sizeof(struct in_addr);
1486                                 break;
1487
1488                         case IPOPT_TS_PRESPEC:
1489                                 if (off + sizeof(n_time) +
1490                                     sizeof(struct in_addr) > optlen) {
1491                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1492                                         goto bad;
1493                                 }
1494                                 (void)memcpy(&ipaddr.sin_addr, sin,
1495                                     sizeof(struct in_addr));
1496                                 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
1497                                         continue;
1498                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1499                                 off += sizeof(struct in_addr);
1500                                 break;
1501
1502                         default:
1503                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
1504                                 goto bad;
1505                         }
1506                         ntime = iptime();
1507                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
1508                         cp[IPOPT_OFFSET] += sizeof(n_time);
1509                 }
1510         }
1511         if (forward && ipforwarding) {
1512                 ip_forward(m, 1, next_hop);
1513                 return (1);
1514         }
1515         return (0);
1516 bad:
1517         icmp_error(m, type, code, 0, 0);
1518         ipstat.ips_badoptions++;
1519         return (1);
1520 }
1521
1522 /*
1523  * Given address of next destination (final or next hop),
1524  * return internet address info of interface to be used to get there.
1525  */
1526 struct in_ifaddr *
1527 ip_rtaddr(dst, rt)
1528         struct in_addr dst;
1529         struct route *rt;
1530 {
1531         struct sockaddr_in *sin;
1532
1533         sin = (struct sockaddr_in *)&rt->ro_dst;
1534
1535         if (rt->ro_rt == 0 ||
1536             dst.s_addr != sin->sin_addr.s_addr) {
1537                 if (rt->ro_rt) {
1538                         RTFREE(rt->ro_rt);
1539                         rt->ro_rt = 0;
1540                 }
1541                 sin->sin_family = AF_INET;
1542                 sin->sin_len = sizeof(*sin);
1543                 sin->sin_addr = dst;
1544
1545                 rtalloc_ign(rt, RTF_PRCLONING);
1546         }
1547         if (rt->ro_rt == 0)
1548                 return ((struct in_ifaddr *)0);
1549         return (ifatoia(rt->ro_rt->rt_ifa));
1550 }
1551
1552 /*
1553  * Save incoming source route for use in replies,
1554  * to be picked up later by ip_srcroute if the receiver is interested.
1555  */
1556 void
1557 save_rte(option, dst)
1558         u_char *option;
1559         struct in_addr dst;
1560 {
1561         unsigned olen;
1562
1563         olen = option[IPOPT_OLEN];
1564 #ifdef DIAGNOSTIC
1565         if (ipprintfs)
1566                 printf("save_rte: olen %d\n", olen);
1567 #endif
1568         if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
1569                 return;
1570         bcopy(option, ip_srcrt.srcopt, olen);
1571         ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1572         ip_srcrt.dst = dst;
1573 }
1574
1575 /*
1576  * Retrieve incoming source route for use in replies,
1577  * in the same form used by setsockopt.
1578  * The first hop is placed before the options, will be removed later.
1579  */
1580 struct mbuf *
1581 ip_srcroute()
1582 {
1583         struct in_addr *p, *q;
1584         struct mbuf *m;
1585
1586         if (ip_nhops == 0)
1587                 return ((struct mbuf *)0);
1588         m = m_get(M_DONTWAIT, MT_HEADER);
1589         if (m == 0)
1590                 return ((struct mbuf *)0);
1591
1592 #define OPTSIZ  (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1593
1594         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1595         m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
1596             OPTSIZ;
1597 #ifdef DIAGNOSTIC
1598         if (ipprintfs)
1599                 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1600 #endif
1601
1602         /*
1603          * First save first hop for return route
1604          */
1605         p = &ip_srcrt.route[ip_nhops - 1];
1606         *(mtod(m, struct in_addr *)) = *p--;
1607 #ifdef DIAGNOSTIC
1608         if (ipprintfs)
1609                 printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr));
1610 #endif
1611
1612         /*
1613          * Copy option fields and padding (nop) to mbuf.
1614          */
1615         ip_srcrt.nop = IPOPT_NOP;
1616         ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1617         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
1618             &ip_srcrt.nop, OPTSIZ);
1619         q = (struct in_addr *)(mtod(m, caddr_t) +
1620             sizeof(struct in_addr) + OPTSIZ);
1621 #undef OPTSIZ
1622         /*
1623          * Record return path as an IP source route,
1624          * reversing the path (pointers are now aligned).
1625          */
1626         while (p >= ip_srcrt.route) {
1627 #ifdef DIAGNOSTIC
1628                 if (ipprintfs)
1629                         printf(" %lx", (u_long)ntohl(q->s_addr));
1630 #endif
1631                 *q++ = *p--;
1632         }
1633         /*
1634          * Last hop goes to final destination.
1635          */
1636         *q = ip_srcrt.dst;
1637 #ifdef DIAGNOSTIC
1638         if (ipprintfs)
1639                 printf(" %lx\n", (u_long)ntohl(q->s_addr));
1640 #endif
1641         return (m);
1642 }
1643
1644 /*
1645  * Strip out IP options, at higher
1646  * level protocol in the kernel.
1647  * Second argument is buffer to which options
1648  * will be moved, and return value is their length.
1649  * XXX should be deleted; last arg currently ignored.
1650  */
1651 void
1652 ip_stripoptions(m, mopt)
1653         struct mbuf *m;
1654         struct mbuf *mopt;
1655 {
1656         int i;
1657         struct ip *ip = mtod(m, struct ip *);
1658         caddr_t opts;
1659         int olen;
1660
1661         olen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
1662         opts = (caddr_t)(ip + 1);
1663         i = m->m_len - (sizeof (struct ip) + olen);
1664         bcopy(opts + olen, opts, (unsigned)i);
1665         m->m_len -= olen;
1666         if (m->m_flags & M_PKTHDR)
1667                 m->m_pkthdr.len -= olen;
1668         ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2);
1669 }
1670
1671 u_char inetctlerrmap[PRC_NCMDS] = {
1672         0,              0,              0,              0,
1673         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
1674         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
1675         EMSGSIZE,       EHOSTUNREACH,   0,              0,
1676         0,              0,              0,              0,
1677         ENOPROTOOPT,    ECONNREFUSED
1678 };
1679
1680 /*
1681  * Forward a packet.  If some error occurs return the sender
1682  * an icmp packet.  Note we can't always generate a meaningful
1683  * icmp message because icmp doesn't have a large enough repertoire
1684  * of codes and types.
1685  *
1686  * If not forwarding, just drop the packet.  This could be confusing
1687  * if ipforwarding was zero but some routing protocol was advancing
1688  * us as a gateway to somewhere.  However, we must let the routing
1689  * protocol deal with that.
1690  *
1691  * The srcrt parameter indicates whether the packet is being forwarded
1692  * via a source route.
1693  */
1694 static void
1695 ip_forward(struct mbuf *m, int srcrt, struct sockaddr_in *next_hop)
1696 {
1697         struct ip *ip = mtod(m, struct ip *);
1698         struct sockaddr_in *sin;
1699         struct rtentry *rt;
1700         int error, type = 0, code = 0;
1701         struct mbuf *mcopy;
1702         n_long dest;
1703         struct in_addr pkt_dst;
1704         struct ifnet *destifp;
1705 #if defined(IPSEC) || defined(FAST_IPSEC)
1706         struct ifnet dummyifp;
1707 #endif
1708
1709         dest = 0;
1710         /*
1711          * Cache the destination address of the packet; this may be
1712          * changed by use of 'ipfw fwd'.
1713          */
1714         pkt_dst = next_hop ? next_hop->sin_addr : ip->ip_dst;
1715
1716 #ifdef DIAGNOSTIC
1717         if (ipprintfs)
1718                 printf("forward: src %lx dst %lx ttl %x\n",
1719                     (u_long)ip->ip_src.s_addr, (u_long)pkt_dst.s_addr,
1720                     ip->ip_ttl);
1721 #endif
1722
1723
1724         if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(pkt_dst) == 0) {
1725                 ipstat.ips_cantforward++;
1726                 m_freem(m);
1727                 return;
1728         }
1729 #ifdef IPSTEALTH
1730         if (!ipstealth) {
1731 #endif
1732                 if (ip->ip_ttl <= IPTTLDEC) {
1733                         icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
1734                             dest, 0);
1735                         return;
1736                 }
1737 #ifdef IPSTEALTH
1738         }
1739 #endif
1740
1741         sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
1742         if ((rt = ipforward_rt.ro_rt) == 0 ||
1743             pkt_dst.s_addr != sin->sin_addr.s_addr) {
1744                 if (ipforward_rt.ro_rt) {
1745                         RTFREE(ipforward_rt.ro_rt);
1746                         ipforward_rt.ro_rt = 0;
1747                 }
1748                 sin->sin_family = AF_INET;
1749                 sin->sin_len = sizeof(*sin);
1750                 sin->sin_addr = pkt_dst;
1751
1752                 rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
1753                 if (ipforward_rt.ro_rt == 0) {
1754                         icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1755                         return;
1756                 }
1757                 rt = ipforward_rt.ro_rt;
1758         }
1759
1760         /*
1761          * Save the IP header and at most 8 bytes of the payload,
1762          * in case we need to generate an ICMP message to the src.
1763          *
1764          * XXX this can be optimized a lot by saving the data in a local
1765          * buffer on the stack (72 bytes at most), and only allocating the
1766          * mbuf if really necessary. The vast majority of the packets
1767          * are forwarded without having to send an ICMP back (either
1768          * because unnecessary, or because rate limited), so we are
1769          * really we are wasting a lot of work here.
1770          *
1771          * We don't use m_copy() because it might return a reference
1772          * to a shared cluster. Both this function and ip_output()
1773          * assume exclusive access to the IP header in `m', so any
1774          * data in a cluster may change before we reach icmp_error().
1775          */
1776         MGET(mcopy, M_DONTWAIT, m->m_type);
1777         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
1778                 /*
1779                  * It's probably ok if the pkthdr dup fails (because
1780                  * the deep copy of the tag chain failed), but for now
1781                  * be conservative and just discard the copy since
1782                  * code below may some day want the tags.
1783                  */
1784                 m_free(mcopy);
1785                 mcopy = NULL;
1786         }
1787         if (mcopy != NULL) {
1788                 mcopy->m_len = imin((IP_VHL_HL(ip->ip_vhl) << 2) + 8,
1789                     (int)ip->ip_len);
1790                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
1791         }
1792
1793 #ifdef IPSTEALTH
1794         if (!ipstealth) {
1795 #endif
1796                 ip->ip_ttl -= IPTTLDEC;
1797 #ifdef IPSTEALTH
1798         }
1799 #endif
1800
1801         /*
1802          * If forwarding packet using same interface that it came in on,
1803          * perhaps should send a redirect to sender to shortcut a hop.
1804          * Only send redirect if source is sending directly to us,
1805          * and if packet was not source routed (or has any options).
1806          * Also, don't send redirect if forwarding using a default route
1807          * or a route modified by a redirect.
1808          */
1809         if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1810             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1811             satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1812             ipsendredirects && !srcrt && !next_hop) {
1813 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1814                 u_long src = ntohl(ip->ip_src.s_addr);
1815
1816                 if (RTA(rt) &&
1817                     (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1818                     if (rt->rt_flags & RTF_GATEWAY)
1819                         dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1820                     else
1821                         dest = pkt_dst.s_addr;
1822                     /* Router requirements says to only send host redirects */
1823                     type = ICMP_REDIRECT;
1824                     code = ICMP_REDIRECT_HOST;
1825 #ifdef DIAGNOSTIC
1826                     if (ipprintfs)
1827                         printf("redirect (%d) to %lx\n", code, (u_long)dest);
1828 #endif
1829                 }
1830         }
1831
1832     {
1833         struct m_hdr tag;
1834
1835         if (next_hop) {
1836                 /* Pass IPFORWARD info if available */
1837
1838                 tag.mh_type = MT_TAG;
1839                 tag.mh_flags = PACKET_TAG_IPFORWARD;
1840                 tag.mh_data = (caddr_t)next_hop;
1841                 tag.mh_next = m;
1842                 m = (struct mbuf *)&tag;
1843         }
1844         error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
1845                           IP_FORWARDING, 0, NULL);
1846     }
1847         if (error)
1848                 ipstat.ips_cantforward++;
1849         else {
1850                 ipstat.ips_forward++;
1851                 if (type)
1852                         ipstat.ips_redirectsent++;
1853                 else {
1854                         if (mcopy) {
1855                                 ipflow_create(&ipforward_rt, mcopy);
1856                                 m_freem(mcopy);
1857                         }
1858                         return;
1859                 }
1860         }
1861         if (mcopy == NULL)
1862                 return;
1863         destifp = NULL;
1864
1865         switch (error) {
1866
1867         case 0:                         /* forwarded, but need redirect */
1868                 /* type, code set above */
1869                 break;
1870
1871         case ENETUNREACH:               /* shouldn't happen, checked above */
1872         case EHOSTUNREACH:
1873         case ENETDOWN:
1874         case EHOSTDOWN:
1875         default:
1876                 type = ICMP_UNREACH;
1877                 code = ICMP_UNREACH_HOST;
1878                 break;
1879
1880         case EMSGSIZE:
1881                 type = ICMP_UNREACH;
1882                 code = ICMP_UNREACH_NEEDFRAG;
1883 #ifdef IPSEC
1884                 /*
1885                  * If the packet is routed over IPsec tunnel, tell the
1886                  * originator the tunnel MTU.
1887                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1888                  * XXX quickhack!!!
1889                  */
1890                 if (ipforward_rt.ro_rt) {
1891                         struct secpolicy *sp = NULL;
1892                         int ipsecerror;
1893                         int ipsechdr;
1894                         struct route *ro;
1895
1896                         sp = ipsec4_getpolicybyaddr(mcopy,
1897                                                     IPSEC_DIR_OUTBOUND,
1898                                                     IP_FORWARDING,
1899                                                     &ipsecerror);
1900
1901                         if (sp == NULL)
1902                                 destifp = ipforward_rt.ro_rt->rt_ifp;
1903                         else {
1904                                 /* count IPsec header size */
1905                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1906                                                          IPSEC_DIR_OUTBOUND,
1907                                                          NULL);
1908
1909                                 /*
1910                                  * find the correct route for outer IPv4
1911                                  * header, compute tunnel MTU.
1912                                  *
1913                                  * XXX BUG ALERT
1914                                  * The "dummyifp" code relies upon the fact
1915                                  * that icmp_error() touches only ifp->if_mtu.
1916                                  */
1917                                 /*XXX*/
1918                                 destifp = NULL;
1919                                 if (sp->req != NULL
1920                                  && sp->req->sav != NULL
1921                                  && sp->req->sav->sah != NULL) {
1922                                         ro = &sp->req->sav->sah->sa_route;
1923                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1924                                                 dummyifp.if_mtu =
1925                                                     ro->ro_rt->rt_ifp->if_mtu;
1926                                                 dummyifp.if_mtu -= ipsechdr;
1927                                                 destifp = &dummyifp;
1928                                         }
1929                                 }
1930
1931                                 key_freesp(sp);
1932                         }
1933                 }
1934 #elif FAST_IPSEC
1935                 /*
1936                  * If the packet is routed over IPsec tunnel, tell the
1937                  * originator the tunnel MTU.
1938                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1939                  * XXX quickhack!!!
1940                  */
1941                 if (ipforward_rt.ro_rt) {
1942                         struct secpolicy *sp = NULL;
1943                         int ipsecerror;
1944                         int ipsechdr;
1945                         struct route *ro;
1946
1947                         sp = ipsec_getpolicybyaddr(mcopy,
1948                                                    IPSEC_DIR_OUTBOUND,
1949                                                    IP_FORWARDING,
1950                                                    &ipsecerror);
1951
1952                         if (sp == NULL)
1953                                 destifp = ipforward_rt.ro_rt->rt_ifp;
1954                         else {
1955                                 /* count IPsec header size */
1956                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1957                                                          IPSEC_DIR_OUTBOUND,
1958                                                          NULL);
1959
1960                                 /*
1961                                  * find the correct route for outer IPv4
1962                                  * header, compute tunnel MTU.
1963                                  *
1964                                  * XXX BUG ALERT
1965                                  * The "dummyifp" code relies upon the fact
1966                                  * that icmp_error() touches only ifp->if_mtu.
1967                                  */
1968                                 /*XXX*/
1969                                 destifp = NULL;
1970                                 if (sp->req != NULL
1971                                  && sp->req->sav != NULL
1972                                  && sp->req->sav->sah != NULL) {
1973                                         ro = &sp->req->sav->sah->sa_route;
1974                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1975                                                 dummyifp.if_mtu =
1976                                                     ro->ro_rt->rt_ifp->if_mtu;
1977                                                 dummyifp.if_mtu -= ipsechdr;
1978                                                 destifp = &dummyifp;
1979                                         }
1980                                 }
1981
1982                                 KEY_FREESP(&sp);
1983                         }
1984                 }
1985 #else /* !IPSEC && !FAST_IPSEC */
1986                 if (ipforward_rt.ro_rt)
1987                         destifp = ipforward_rt.ro_rt->rt_ifp;
1988 #endif /*IPSEC*/
1989                 ipstat.ips_cantfrag++;
1990                 break;
1991
1992         case ENOBUFS:
1993                 /*
1994                  * A router should not generate ICMP_SOURCEQUENCH as
1995                  * required in RFC1812 Requirements for IP Version 4 Routers.
1996                  * Source quench could be a big problem under DoS attacks,
1997                  * or if the underlying interface is rate-limited.
1998                  * Those who need source quench packets may re-enable them
1999                  * via the net.inet.ip.sendsourcequench sysctl.
2000                  */
2001                 if (ip_sendsourcequench == 0) {
2002                         m_freem(mcopy);
2003                         return;
2004                 } else {
2005                         type = ICMP_SOURCEQUENCH;
2006                         code = 0;
2007                 }
2008                 break;
2009
2010         case EACCES:                    /* ipfw denied packet */
2011                 m_freem(mcopy);
2012                 return;
2013         }
2014         icmp_error(mcopy, type, code, dest, destifp);
2015 }
2016
2017 void
2018 ip_savecontrol(inp, mp, ip, m)
2019         struct inpcb *inp;
2020         struct mbuf **mp;
2021         struct ip *ip;
2022         struct mbuf *m;
2023 {
2024         if (inp->inp_socket->so_options & SO_TIMESTAMP) {
2025                 struct timeval tv;
2026
2027                 microtime(&tv);
2028                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
2029                         SCM_TIMESTAMP, SOL_SOCKET);
2030                 if (*mp)
2031                         mp = &(*mp)->m_next;
2032         }
2033         if (inp->inp_flags & INP_RECVDSTADDR) {
2034                 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
2035                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
2036                 if (*mp)
2037                         mp = &(*mp)->m_next;
2038         }
2039 #ifdef notyet
2040         /* XXX
2041          * Moving these out of udp_input() made them even more broken
2042          * than they already were.
2043          */
2044         /* options were tossed already */
2045         if (inp->inp_flags & INP_RECVOPTS) {
2046                 *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
2047                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
2048                 if (*mp)
2049                         mp = &(*mp)->m_next;
2050         }
2051         /* ip_srcroute doesn't do what we want here, need to fix */
2052         if (inp->inp_flags & INP_RECVRETOPTS) {
2053                 *mp = sbcreatecontrol((caddr_t) ip_srcroute(),
2054                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
2055                 if (*mp)
2056                         mp = &(*mp)->m_next;
2057         }
2058 #endif
2059         if (inp->inp_flags & INP_RECVIF) {
2060                 struct ifnet *ifp;
2061                 struct sdlbuf {
2062                         struct sockaddr_dl sdl;
2063                         u_char  pad[32];
2064                 } sdlbuf;
2065                 struct sockaddr_dl *sdp;
2066                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
2067
2068                 if (((ifp = m->m_pkthdr.rcvif))
2069                 && ( ifp->if_index && (ifp->if_index <= if_index))) {
2070                         sdp = (struct sockaddr_dl *)(ifnet_addrs
2071                                         [ifp->if_index - 1]->ifa_addr);
2072                         /*
2073                          * Change our mind and don't try copy.
2074                          */
2075                         if ((sdp->sdl_family != AF_LINK)
2076                         || (sdp->sdl_len > sizeof(sdlbuf))) {
2077                                 goto makedummy;
2078                         }
2079                         bcopy(sdp, sdl2, sdp->sdl_len);
2080                 } else {
2081 makedummy:
2082                         sdl2->sdl_len
2083                                 = offsetof(struct sockaddr_dl, sdl_data[0]);
2084                         sdl2->sdl_family = AF_LINK;
2085                         sdl2->sdl_index = 0;
2086                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
2087                 }
2088                 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
2089                         IP_RECVIF, IPPROTO_IP);
2090                 if (*mp)
2091                         mp = &(*mp)->m_next;
2092         }
2093 }
2094
2095 /*
2096  * XXX these routines are called from the upper part of the kernel.
2097  *
2098  * They could also be moved to ip_mroute.c, since all the RSVP
2099  *  handling is done there already.
2100  */
2101 int
2102 ip_rsvp_init(struct socket *so)
2103 {
2104         if (so->so_type != SOCK_RAW ||
2105             so->so_proto->pr_protocol != IPPROTO_RSVP)
2106                 return EOPNOTSUPP;
2107
2108         if (ip_rsvpd != NULL)
2109                 return EADDRINUSE;
2110
2111         ip_rsvpd = so;
2112         /*
2113          * This may seem silly, but we need to be sure we don't over-increment
2114          * the RSVP counter, in case something slips up.
2115          */
2116         if (!ip_rsvp_on) {
2117                 ip_rsvp_on = 1;
2118                 rsvp_on++;
2119         }
2120
2121         return 0;
2122 }
2123
2124 int
2125 ip_rsvp_done(void)
2126 {
2127         ip_rsvpd = NULL;
2128         /*
2129          * This may seem silly, but we need to be sure we don't over-decrement
2130          * the RSVP counter, in case something slips up.
2131          */
2132         if (ip_rsvp_on) {
2133                 ip_rsvp_on = 0;
2134                 rsvp_on--;
2135         }
2136         return 0;
2137 }
2138
2139 void
2140 rsvp_input(struct mbuf *m, int off, int proto)  /* XXX must fixup manually */
2141 {
2142         if (rsvp_input_p) { /* call the real one if loaded */
2143                 rsvp_input_p(m, off, proto);
2144                 return;
2145         }
2146
2147         /* Can still get packets with rsvp_on = 0 if there is a local member
2148          * of the group to which the RSVP packet is addressed.  But in this
2149          * case we want to throw the packet away.
2150          */
2151
2152         if (!rsvp_on) {
2153                 m_freem(m);
2154                 return;
2155         }
2156
2157         if (ip_rsvpd != NULL) {
2158                 rip_input(m, off, proto);
2159                 return;
2160         }
2161         /* Drop the packet */
2162         m_freem(m);
2163 }
2164