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 1.30 2004/06/04 03:57:41 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_pfil_hooks.h"
  48 #include "opt_random_ip_id.h"
  49
  50 #include <sys/param.h>
  51 #include <sys/systm.h>
  52 #include <sys/mbuf.h>
  53 #include <sys/malloc.h>
  54 #include <sys/mpipe.h>
  55 #include <sys/domain.h>
  56 #include <sys/protosw.h>
  57 #include <sys/socket.h>
  58 #include <sys/time.h>
  59 #include <sys/globaldata.h>
  60 #include <sys/thread.h>
  61 #include <sys/kernel.h>
  62 #include <sys/syslog.h>
  63 #include <sys/sysctl.h>
  64 #include <sys/in_cksum.h>
  65
  66 #include <sys/thread2.h>
  67 #include <sys/msgport2.h>
  68
  69 #include <machine/stdarg.h>
  70
  71 #include <net/if.h>
  72 #include <net/if_types.h>
  73 #include <net/if_var.h>
  74 #include <net/if_dl.h>
  75 #ifdef PFIL_HOOKS
  76 #include <net/pfil.h>
  77 #endif
  78 #include <net/route.h>
  79 #include <net/netisr.h>
  80 #include <net/intrq.h>
  81
  82 #include <netinet/in.h>
  83 #include <netinet/in_systm.h>
  84 #include <netinet/in_var.h>
  85 #include <netinet/ip.h>
  86 #include <netinet/in_pcb.h>
  87 #include <netinet/ip_var.h>
  88 #include <netinet/ip_icmp.h>
  89
  90 #include <netinet/ipprotosw.h>
  91
  92 #include <sys/socketvar.h>
  93
  94 #include <net/ipfw/ip_fw.h>
  95 #include <net/dummynet/ip_dummynet.h>
  96
  97 #ifdef IPSEC
  98 #include <netinet6/ipsec.h>
  99 #include <netproto/key/key.h>
 100 #endif
 101
 102 #ifdef FAST_IPSEC
 103 #include <netipsec/ipsec.h>
 104 #include <netipsec/key.h>
 105 #endif
 106
 107 int rsvp_on = 0;
 108 static int ip_rsvp_on;
 109 struct socket *ip_rsvpd;
 110
 111 int ipforwarding = 0;
 112 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
 113     &ipforwarding, 0, "Enable IP forwarding between interfaces");
 114
 115 static int ipsendredirects = 1; /* XXX */
 116 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
 117     &ipsendredirects, 0, "Enable sending IP redirects");
 118
 119 int ip_defttl = IPDEFTTL;
 120 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
 121     &ip_defttl, 0, "Maximum TTL on IP packets");
 122
 123 static int ip_dosourceroute = 0;
 124 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
 125     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
 126
 127 static int ip_acceptsourceroute = 0;
 128 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
 129     CTLFLAG_RW, &ip_acceptsourceroute, 0,
 130     "Enable accepting source routed IP packets");
 131
 132 static int ip_keepfaith = 0;
 133 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
 134     &ip_keepfaith, 0,
 135     "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
 136
 137 static int nipq = 0;    /* total # of reass queues */
 138 static int maxnipq;
 139 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
 140     &maxnipq, 0,
 141     "Maximum number of IPv4 fragment reassembly queue entries");
 142
 143 static int maxfragsperpacket;
 144 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
 145     &maxfragsperpacket, 0,
 146     "Maximum number of IPv4 fragments allowed per packet");
 147
 148 static int ip_sendsourcequench = 0;
 149 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
 150     &ip_sendsourcequench, 0,
 151     "Enable the transmission of source quench packets");
 152
 153 /*
 154  * XXX - Setting ip_checkinterface mostly implements the receive side of
 155  * the Strong ES model described in RFC 1122, but since the routing table
 156  * and transmit implementation do not implement the Strong ES model,
 157  * setting this to 1 results in an odd hybrid.
 158  *
 159  * XXX - ip_checkinterface currently must be disabled if you use ipnat
 160  * to translate the destination address to another local interface.
 161  *
 162  * XXX - ip_checkinterface must be disabled if you add IP aliases
 163  * to the loopback interface instead of the interface where the
 164  * packets for those addresses are received.
 165  */
 166 static int ip_checkinterface = 0;
 167 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
 168     &ip_checkinterface, 0, "Verify packet arrives on correct interface");
 169
 170 #ifdef DIAGNOSTIC
 171 static int ipprintfs = 0;
 172 #endif
 173
 174 static struct ifqueue ipintrq;
 175 static int ipqmaxlen = IFQ_MAXLEN;
 176
 177 extern  struct domain inetdomain;
 178 extern  struct ipprotosw inetsw[];
 179 u_char  ip_protox[IPPROTO_MAX];
 180 struct  in_ifaddrhead in_ifaddrhead;            /* first inet address */
 181 struct  in_ifaddrhashhead *in_ifaddrhashtbl;    /* inet addr hash table */
 182 u_long  in_ifaddrhmask;                         /* mask for hash table */
 183
 184 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
 185     &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
 186 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
 187     &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
 188
 189 struct ip_stats ipstats_ary[MAXCPU];
 190 #ifdef SMP
 191 static int
 192 sysctl_ipstats(SYSCTL_HANDLER_ARGS)
 193 {
 194         int cpu, error = 0;
 195
 196         for (cpu = 0; cpu < ncpus; ++cpu) {
 197                 if ((error = SYSCTL_OUT(req, (void *)&ipstats_ary[cpu],
 198                                         sizeof(struct ip_stats))))
 199                         break;
 200                 if ((error = SYSCTL_IN(req, (void *)&ipstats_ary[cpu],
 201                                        sizeof(struct ip_stats))))
 202                         break;
 203         }
 204
 205         return (error);
 206 }
 207 SYSCTL_PROC(_net_inet_ip, IPCTL_STATS, stats, (CTLTYPE_OPAQUE | CTLFLAG_RW),
 208     0, 0, sysctl_ipstats, "S,ip_stats", "IP statistics");
 209 #else
 210 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
 211     &ipstat, ip_stats, "IP statistics");
 212 #endif
 213
 214 /* Packet reassembly stuff */
 215 #define IPREASS_NHASH_LOG2      6
 216 #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
 217 #define IPREASS_HMASK           (IPREASS_NHASH - 1)
 218 #define IPREASS_HASH(x,y)                                               \
 219     (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
 220
 221 static struct ipq ipq[IPREASS_NHASH];
 222 const  int    ipintrq_present = 1;
 223
 224 #ifdef IPCTL_DEFMTU
 225 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
 226     &ip_mtu, 0, "Default MTU");
 227 #endif
 228
 229 #ifdef IPSTEALTH
 230 static int ipstealth = 0;
 231 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW, &ipstealth, 0, "");
 232 #else
 233 static const int ipstealth = 0;
 234 #endif
 235
 236
 237 /* Firewall hooks */
 238 ip_fw_chk_t *ip_fw_chk_ptr;
 239 int fw_enable = 1;
 240 int fw_one_pass = 1;
 241
 242 /* Dummynet hooks */
 243 ip_dn_io_t *ip_dn_io_ptr;
 244
 245 #ifdef PFIL_HOOKS
 246 struct pfil_head inet_pfil_hook;
 247 #endif
 248
 249 /*
 250  * XXX this is ugly -- the following two global variables are
 251  * used to store packet state while it travels through the stack.
 252  * Note that the code even makes assumptions on the size and
 253  * alignment of fields inside struct ip_srcrt so e.g. adding some
 254  * fields will break the code. This needs to be fixed.
 255  *
 256  * We need to save the IP options in case a protocol wants to respond
 257  * to an incoming packet over the same route if the packet got here
 258  * using IP source routing.  This allows connection establishment and
 259  * maintenance when the remote end is on a network that is not known
 260  * to us.
 261  */
 262 static int ip_nhops = 0;
 263
 264 static  struct ip_srcrt {
 265         struct  in_addr dst;                    /* final destination */
 266         char    nop;                            /* one NOP to align */
 267         char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
 268         struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
 269 } ip_srcrt;
 270
 271 static MALLOC_DEFINE(M_IPQ, "ipq", "IP Fragment Management");
 272 static struct malloc_pipe ipq_mpipe;
 273
 274 static void             save_rte (u_char *, struct in_addr);
 275 static int              ip_dooptions (struct mbuf *m, int,
 276                                         struct sockaddr_in *next_hop);
 277 static void             ip_forward (struct mbuf *m, int srcrt,
 278                                         struct sockaddr_in *next_hop);
 279 static void             ip_freef (struct ipq *);
 280 static int              ip_input_handler (struct netmsg *);
 281 static struct mbuf      *ip_reass (struct mbuf *, struct ipq *,
 282                                         struct ipq *, u_int32_t *, u_int16_t *);
 283
 284 /*
 285  * IP initialization: fill in IP protocol switch table.
 286  * All protocols not implemented in kernel go to raw IP protocol handler.
 287  */
 288 void
 289 ip_init(void)
 290 {
 291         struct ipprotosw *pr;
 292         int i;
 293 #ifdef SMP
 294         int cpu;
 295 #endif
 296
 297         /*
 298          * Make sure we can handle a reasonable number of fragments but
 299          * cap it at 4000 (XXX).
 300          */
 301         mpipe_init(&ipq_mpipe, M_IPQ, sizeof(struct ipq),
 302                     IFQ_MAXLEN, 4000, 0, NULL);
 303         TAILQ_INIT(&in_ifaddrhead);
 304         in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask);
 305         pr = (struct ipprotosw *)pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 306         if (pr == NULL)
 307                 panic("ip_init");
 308         for (i = 0; i < IPPROTO_MAX; i++)
 309                 ip_protox[i] = pr - inetsw;
 310         for (pr = (struct ipprotosw *)inetdomain.dom_protosw;
 311              pr < (struct ipprotosw *)inetdomain.dom_protoswNPROTOSW; pr++)
 312                 if (pr->pr_domain->dom_family == PF_INET &&
 313                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
 314                         ip_protox[pr->pr_protocol] = pr - inetsw;
 315
 316 #ifdef PFIL_HOOKS
 317         inet_pfil_hook.ph_type = PFIL_TYPE_AF;
 318         inet_pfil_hook.ph_af = AF_INET;
 319         if ((i = pfil_head_register(&inet_pfil_hook)) != 0)
 320                 printf("%s: WARNING: unable to register pfil hook, "
 321                         "error %d\n", __func__, i);
 322 #endif
 323
 324         for (i = 0; i < IPREASS_NHASH; i++)
 325             ipq[i].next = ipq[i].prev = &ipq[i];
 326
 327         maxnipq = nmbclusters / 32;
 328         maxfragsperpacket = 16;
 329
 330 #ifndef RANDOM_IP_ID
 331         ip_id = time_second & 0xffff;
 332 #endif
 333         ipintrq.ifq_maxlen = ipqmaxlen;
 334
 335         /*
 336          * Initialize IP statistics.
 337          *
 338          * It is layed out as an array which is has one element for UP,
 339          * and SMP_MAXCPU elements for SMP.  This allows us to retain
 340          * the access mechanism from userland for both UP and SMP.
 341          */
 342 #ifdef SMP
 343         for (cpu = 0; cpu < ncpus; ++cpu) {
 344                 bzero(&ipstats_ary[cpu], sizeof(struct ip_stats));
 345         }
 346 #else
 347         bzero(&ipstat, sizeof(struct ip_stats));
 348 #endif
 349
 350         netisr_register(NETISR_IP, ip_mport, ip_input_handler);
 351 }
 352
 353 /*
 354  * XXX watch out this one. It is perhaps used as a cache for
 355  * the most recently used route ? it is cleared in in_addroute()
 356  * when a new route is successfully created.
 357  */
 358 struct route ipforward_rt;
 359 static struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
 360
 361 /* Do transport protocol processing. */
 362 static void
 363 transport_processing_oncpu(struct mbuf *m, int hlen, struct ip *ip,
 364                            struct sockaddr_in *nexthop)
 365 {
 366         /*
 367          * Switch out to protocol's input routine.
 368          */
 369         if (nexthop && ip->ip_p == IPPROTO_TCP) {
 370                 /* TCP needs IPFORWARD info if available */
 371                 struct m_hdr tag;
 372
 373                 tag.mh_type = MT_TAG;
 374                 tag.mh_flags = PACKET_TAG_IPFORWARD;
 375                 tag.mh_data = (caddr_t)nexthop;
 376                 tag.mh_next = m;
 377
 378                 (*inetsw[ip_protox[ip->ip_p]].pr_input)
 379                     ((struct mbuf *)&tag, hlen, ip->ip_p);
 380         } else {
 381                 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen, ip->ip_p);
 382         }
 383 }
 384
 385 struct netmsg_transport_packet {
 386         struct lwkt_msg         nm_lmsg;
 387         struct mbuf             *nm_mbuf;
 388         int                     nm_hlen;
 389         boolean_t               nm_hasnexthop;
 390         struct sockaddr_in      nm_nexthop;
 391 };
 392
 393 static int
 394 transport_processing_handler(lwkt_msg_t lmsg)
 395 {
 396         struct netmsg_transport_packet *msg = (void *)lmsg;
 397         struct sockaddr_in *nexthop;
 398         struct ip *ip;
 399
 400         ip = mtod(msg->nm_mbuf, struct ip *);
 401         nexthop = msg->nm_hasnexthop ? &msg->nm_nexthop : NULL;
 402         transport_processing_oncpu(msg->nm_mbuf, msg->nm_hlen, ip, nexthop);
 403         lwkt_replymsg(lmsg, 0);
 404         return(EASYNC);
 405 }
 406
 407 static int
 408 ip_input_handler(struct netmsg *msg0)
 409 {
 410         struct mbuf *m = ((struct netmsg_packet *)msg0)->nm_packet;
 411
 412         ip_input(m);
 413         lwkt_replymsg(&msg0->nm_lmsg, 0);
 414         return(EASYNC);
 415 }
 416
 417 /*
 418  * Ip input routine.  Checksum and byte swap header.  If fragmented
 419  * try to reassemble.  Process options.  Pass to next level.
 420  */
 421 void
 422 ip_input(struct mbuf *m)
 423 {
 424         struct ip *ip;
 425         struct ipq *fp;
 426         struct in_ifaddr *ia = NULL;
 427         struct ifaddr *ifa;
 428         int i, hlen, checkif;
 429         u_short sum;
 430         struct in_addr pkt_dst;
 431         u_int32_t divert_info = 0;              /* packet divert/tee info */
 432         struct ip_fw_args args;
 433         boolean_t using_srcrt = FALSE;          /* forward (by PFIL_HOOKS) */
 434         boolean_t needredispatch = FALSE;
 435 #ifdef PFIL_HOOKS
 436         struct in_addr odst;                    /* original dst address(NAT) */
 437 #endif
 438 #ifdef FAST_IPSEC
 439         struct m_tag *mtag;
 440         struct tdb_ident *tdbi;
 441         struct secpolicy *sp;
 442         int s, error;
 443 #endif
 444
 445         args.eh = NULL;
 446         args.oif = NULL;
 447         args.rule = NULL;
 448         args.divert_rule = 0;                   /* divert cookie */
 449         args.next_hop = NULL;
 450
 451         /* Grab info from MT_TAG mbufs prepended to the chain. */
 452         for (; m && m->m_type == MT_TAG; m = m->m_next) {
 453                 switch(m->_m_tag_id) {
 454                 default:
 455                         printf("ip_input: unrecognised MT_TAG tag %d\n",
 456                             m->_m_tag_id);
 457                         break;
 458
 459                 case PACKET_TAG_DUMMYNET:
 460                         args.rule = ((struct dn_pkt *)m)->rule;
 461                         break;
 462
 463                 case PACKET_TAG_DIVERT:
 464                         args.divert_rule = (int)m->m_hdr.mh_data & 0xffff;
 465                         break;
 466
 467                 case PACKET_TAG_IPFORWARD:
 468                         args.next_hop = (struct sockaddr_in *)m->m_hdr.mh_data;
 469                         break;
 470                 }
 471         }
 472
 473         KASSERT(m != NULL && (m->m_flags & M_PKTHDR) != 0,
 474             ("ip_input: no HDR"));
 475
 476         if (args.rule) {        /* dummynet already filtered us */
 477                 ip = mtod(m, struct ip *);
 478                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 479                 goto iphack;
 480         }
 481
 482         ipstat.ips_total++;
 483
 484         /* length checks already done in ip_demux() */
 485         KASSERT(m->m_len >= sizeof(ip), ("IP header not in one mbuf"));
 486
 487         ip = mtod(m, struct ip *);
 488
 489         if (IP_VHL_V(ip->ip_vhl) != IPVERSION) {
 490                 ipstat.ips_badvers++;
 491                 goto bad;
 492         }
 493
 494         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 495         /* length checks already done in ip_demux() */
 496         KASSERT(hlen >= sizeof(struct ip), ("IP header len too small"));
 497         KASSERT(m->m_len >= hlen, ("packet shorter than IP header length"));
 498
 499         /* 127/8 must not appear on wire - RFC1122 */
 500         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
 501             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
 502                 if (!(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK)) {
 503                         ipstat.ips_badaddr++;
 504                         goto bad;
 505                 }
 506         }
 507
 508         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
 509                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
 510         } else {
 511                 if (hlen == sizeof(struct ip)) {
 512                         sum = in_cksum_hdr(ip);
 513                 } else {
 514                         sum = in_cksum(m, hlen);
 515                 }
 516         }
 517         if (sum) {
 518                 ipstat.ips_badsum++;
 519                 goto bad;
 520         }
 521
 522         /*
 523          * Convert fields to host representation.
 524          */
 525         ip->ip_len = ntohs(ip->ip_len);
 526         if (ip->ip_len < hlen) {
 527                 ipstat.ips_badlen++;
 528                 goto bad;
 529         }
 530         ip->ip_off = ntohs(ip->ip_off);
 531
 532         /*
 533          * Check that the amount of data in the buffers
 534          * is as at least much as the IP header would have us expect.
 535          * Trim mbufs if longer than we expect.
 536          * Drop packet if shorter than we expect.
 537          */
 538         if (m->m_pkthdr.len < ip->ip_len) {
 539                 ipstat.ips_tooshort++;
 540                 goto bad;
 541         }
 542         if (m->m_pkthdr.len > ip->ip_len) {
 543                 if (m->m_len == m->m_pkthdr.len) {
 544                         m->m_len = ip->ip_len;
 545                         m->m_pkthdr.len = ip->ip_len;
 546                 } else
 547                         m_adj(m, ip->ip_len - m->m_pkthdr.len);
 548         }
 549 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
 550         /*
 551          * Bypass packet filtering for packets from a tunnel (gif).
 552          */
 553         if (ipsec_gethist(m, NULL))
 554                 goto pass;
 555 #endif
 556
 557         /*
 558          * IpHack's section.
 559          * Right now when no processing on packet has done
 560          * and it is still fresh out of network we do our black
 561          * deals with it.
 562          * - Firewall: deny/allow/divert
 563          * - Xlate: translate packet's addr/port (NAT).
 564          * - Pipe: pass pkt through dummynet.
 565          * - Wrap: fake packet's addr/port <unimpl.>
 566          * - Encapsulate: put it in another IP and send out. <unimp.>
 567          */
 568
 569 iphack:
 570
 571 #ifdef PFIL_HOOKS
 572         /*
 573          * Run through list of hooks for input packets.
 574          *
 575          * NB: Beware of the destination address changing (e.g.
 576          *     by NAT rewriting). When this happens, tell
 577          *     ip_forward to do the right thing.
 578          */
 579         if (pfil_has_hooks(&inet_pfil_hook)) {
 580                 odst = ip->ip_dst;
 581                 if (pfil_run_hooks(&inet_pfil_hook, &m,
 582                     m->m_pkthdr.rcvif, PFIL_IN)) {
 583                         return;
 584                 }
 585                 if (m == NULL)                  /* consumed by filter */
 586                         return;
 587                 ip = mtod(m, struct ip *);
 588                 using_srcrt = (odst.s_addr != ip->ip_dst.s_addr);
 589         }
 590 #endif
 591
 592         if (fw_enable && IPFW_LOADED) {
 593                 /*
 594                  * If we've been forwarded from the output side, then
 595                  * skip the firewall a second time
 596                  */
 597                 if (args.next_hop)
 598                         goto ours;
 599
 600                 args.m = m;
 601                 i = ip_fw_chk_ptr(&args);
 602                 m = args.m;
 603
 604                 if ( (i & IP_FW_PORT_DENY_FLAG) || m == NULL) { /* drop */
 605                         if (m)
 606                                 m_freem(m);
 607                         return;
 608                 }
 609                 ip = mtod(m, struct ip *); /* just in case m changed */
 610                 if (i == 0 && args.next_hop == NULL)    /* common case */
 611                         goto pass;
 612                 if (DUMMYNET_LOADED && (i & IP_FW_PORT_DYNT_FLAG)) {
 613                         /* Send packet to the appropriate pipe */
 614                         ip_dn_io_ptr(m, i&0xffff, DN_TO_IP_IN, &args);
 615                         return;
 616                 }
 617 #ifdef IPDIVERT
 618                 if (i != 0 && !(i & IP_FW_PORT_DYNT_FLAG)) {
 619                         /* Divert or tee packet */
 620                         divert_info = i;
 621                         goto ours;
 622                 }
 623 #endif
 624                 if (i == 0 && args.next_hop != NULL)
 625                         goto pass;
 626                 /*
 627                  * if we get here, the packet must be dropped
 628                  */
 629                 m_freem(m);
 630                 return;
 631         }
 632 pass:
 633
 634         /*
 635          * Process options and, if not destined for us,
 636          * ship it on.  ip_dooptions returns 1 when an
 637          * error was detected (causing an icmp message
 638          * to be sent and the original packet to be freed).
 639          */
 640         ip_nhops = 0;           /* for source routed packets */
 641         if (hlen > sizeof(struct ip) && ip_dooptions(m, 0, args.next_hop))
 642                 return;
 643
 644         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
 645          * matter if it is destined to another node, or whether it is
 646          * a multicast one, RSVP wants it! and prevents it from being forwarded
 647          * anywhere else. Also checks if the rsvp daemon is running before
 648          * grabbing the packet.
 649          */
 650         if (rsvp_on && ip->ip_p == IPPROTO_RSVP)
 651                 goto ours;
 652
 653         /*
 654          * Check our list of addresses, to see if the packet is for us.
 655          * If we don't have any addresses, assume any unicast packet
 656          * we receive might be for us (and let the upper layers deal
 657          * with it).
 658          */
 659         if (TAILQ_EMPTY(&in_ifaddrhead) && !(m->m_flags & (M_MCAST | M_BCAST)))
 660                 goto ours;
 661
 662         /*
 663          * Cache the destination address of the packet; this may be
 664          * changed by use of 'ipfw fwd'.
 665          */
 666         pkt_dst = args.next_hop ? args.next_hop->sin_addr : ip->ip_dst;
 667
 668         /*
 669          * Enable a consistency check between the destination address
 670          * and the arrival interface for a unicast packet (the RFC 1122
 671          * strong ES model) if IP forwarding is disabled and the packet
 672          * is not locally generated and the packet is not subject to
 673          * 'ipfw fwd'.
 674          *
 675          * XXX - Checking also should be disabled if the destination
 676          * address is ipnat'ed to a different interface.
 677          *
 678          * XXX - Checking is incompatible with IP aliases added
 679          * to the loopback interface instead of the interface where
 680          * the packets are received.
 681          */
 682         checkif = ip_checkinterface &&
 683                   !ipforwarding &&
 684                   m->m_pkthdr.rcvif != NULL &&
 685                   !(m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) &&
 686                   (args.next_hop == NULL);
 687
 688         /*
 689          * Check for exact addresses in the hash bucket.
 690          */
 691         LIST_FOREACH(ia, INADDR_HASH(pkt_dst.s_addr), ia_hash) {
 692                 /*
 693                  * If the address matches, verify that the packet
 694                  * arrived via the correct interface if checking is
 695                  * enabled.
 696                  */
 697                 if (IA_SIN(ia)->sin_addr.s_addr == pkt_dst.s_addr &&
 698                     (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
 699                         goto ours;
 700         }
 701         /*
 702          * Check for broadcast addresses.
 703          *
 704          * Only accept broadcast packets that arrive via the matching
 705          * interface.  Reception of forwarded directed broadcasts would
 706          * be handled via ip_forward() and ether_output() with the loopback
 707          * into the stack for SIMPLEX interfaces handled by ether_output().
 708          */
 709         if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
 710                 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
 711                         if (ifa->ifa_addr->sa_family != AF_INET)
 712                                 continue;
 713                         ia = ifatoia(ifa);
 714                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 715                                                                 pkt_dst.s_addr)
 716                                 goto ours;
 717                         if (ia->ia_netbroadcast.s_addr == pkt_dst.s_addr)
 718                                 goto ours;
 719 #ifdef BOOTP_COMPAT
 720                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
 721                                 goto ours;
 722 #endif
 723                 }
 724         }
 725         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
 726                 struct in_multi *inm;
 727                 if (ip_mrouter) {
 728                         /*
 729                          * If we are acting as a multicast router, all
 730                          * incoming multicast packets are passed to the
 731                          * kernel-level multicast forwarding function.
 732                          * The packet is returned (relatively) intact; if
 733                          * ip_mforward() returns a non-zero value, the packet
 734                          * must be discarded, else it may be accepted below.
 735                          */
 736                         if (ip_mforward &&
 737                             ip_mforward(ip, m->m_pkthdr.rcvif, m, NULL) != 0) {
 738                                 ipstat.ips_cantforward++;
 739                                 m_freem(m);
 740                                 return;
 741                         }
 742
 743                         /*
 744                          * The process-level routing daemon needs to receive
 745                          * all multicast IGMP packets, whether or not this
 746                          * host belongs to their destination groups.
 747                          */
 748                         if (ip->ip_p == IPPROTO_IGMP)
 749                                 goto ours;
 750                         ipstat.ips_forward++;
 751                 }
 752                 /*
 753                  * See if we belong to the destination multicast group on the
 754                  * arrival interface.
 755                  */
 756                 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
 757                 if (inm == NULL) {
 758                         ipstat.ips_notmember++;
 759                         m_freem(m);
 760                         return;
 761                 }
 762                 goto ours;
 763         }
 764         if (ip->ip_dst.s_addr == INADDR_BROADCAST)
 765                 goto ours;
 766         if (ip->ip_dst.s_addr == INADDR_ANY)
 767                 goto ours;
 768
 769         /*
 770          * FAITH(Firewall Aided Internet Translator)
 771          */
 772         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 773                 if (ip_keepfaith) {
 774                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
 775                                 goto ours;
 776                 }
 777                 m_freem(m);
 778                 return;
 779         }
 780
 781         /*
 782          * Not for us; forward if possible and desirable.
 783          */
 784         if (!ipforwarding) {
 785                 ipstat.ips_cantforward++;
 786                 m_freem(m);
 787         } else {
 788 #ifdef IPSEC
 789                 /*
 790                  * Enforce inbound IPsec SPD.
 791                  */
 792                 if (ipsec4_in_reject(m, NULL)) {
 793                         ipsecstat.in_polvio++;
 794                         goto bad;
 795                 }
 796 #endif
 797 #ifdef FAST_IPSEC
 798                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 799                 s = splnet();
 800                 if (mtag != NULL) {
 801                         tdbi = (struct tdb_ident *)(mtag + 1);
 802                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 803                 } else {
 804                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 805                                                    IP_FORWARDING, &error);
 806                 }
 807                 if (sp == NULL) {       /* NB: can happen if error */
 808                         splx(s);
 809                         /*XXX error stat???*/
 810                         DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 811                         goto bad;
 812                 }
 813
 814                 /*
 815                  * Check security policy against packet attributes.
 816                  */
 817                 error = ipsec_in_reject(sp, m);
 818                 KEY_FREESP(&sp);
 819                 splx(s);
 820                 if (error) {
 821                         ipstat.ips_cantforward++;
 822                         goto bad;
 823                 }
 824 #endif
 825                 ip_forward(m, using_srcrt, args.next_hop);
 826         }
 827         return;
 828
 829 ours:
 830
 831         /*
 832          * IPSTEALTH: Process non-routing options only
 833          * if the packet is destined for us.
 834          */
 835         if (ipstealth &&
 836             hlen > sizeof(struct ip) &&
 837             ip_dooptions(m, 1, args.next_hop))
 838                 return;
 839
 840         /* Count the packet in the ip address stats */
 841         if (ia != NULL) {
 842                 ia->ia_ifa.if_ipackets++;
 843                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
 844         }
 845
 846         /*
 847          * If offset or IP_MF are set, must reassemble.
 848          * Otherwise, nothing need be done.
 849          * (We could look in the reassembly queue to see
 850          * if the packet was previously fragmented,
 851          * but it's not worth the time; just let them time out.)
 852          */
 853         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 854
 855                 /* If maxnipq is 0, never accept fragments. */
 856                 if (maxnipq == 0) {
 857                         ipstat.ips_fragments++;
 858                         ipstat.ips_fragdropped++;
 859                         goto bad;
 860                 }
 861
 862                 sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
 863                 /*
 864                  * Look for queue of fragments
 865                  * of this datagram.
 866                  */
 867                 for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next)
 868                         if (ip->ip_id == fp->ipq_id &&
 869                             ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 870                             ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 871                             ip->ip_p == fp->ipq_p)
 872                                 goto found;
 873
 874                 fp = NULL;
 875
 876                 /*
 877                  * Enforce upper bound on number of fragmented packets
 878                  * for which we attempt reassembly;
 879                  * If maxnipq is -1, accept all fragments without limitation.
 880                  */
 881                 if ((nipq > maxnipq) && (maxnipq > 0)) {
 882                         /*
 883                          * drop something from the tail of the current queue
 884                          * before proceeding further
 885                          */
 886                         if (ipq[sum].prev == &ipq[sum]) {   /* gak */
 887                                 for (i = 0; i < IPREASS_NHASH; i++) {
 888                                         if (ipq[i].prev != &ipq[i]) {
 889                                                 ipstat.ips_fragtimeout +=
 890                                                     ipq[i].prev->ipq_nfrags;
 891                                                 ip_freef(ipq[i].prev);
 892                                                 break;
 893                                         }
 894                                 }
 895                         } else {
 896                                 ipstat.ips_fragtimeout +=
 897                                     ipq[sum].prev->ipq_nfrags;
 898                                 ip_freef(ipq[sum].prev);
 899                         }
 900                 }
 901 found:
 902                 /*
 903                  * Adjust ip_len to not reflect header,
 904                  * convert offset of this to bytes.
 905                  */
 906                 ip->ip_len -= hlen;
 907                 if (ip->ip_off & IP_MF) {
 908                         /*
 909                          * Make sure that fragments have a data length
 910                          * that's a non-zero multiple of 8 bytes.
 911                          */
 912                         if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
 913                                 ipstat.ips_toosmall++; /* XXX */
 914                                 goto bad;
 915                         }
 916                         m->m_flags |= M_FRAG;
 917                 } else
 918                         m->m_flags &= ~M_FRAG;
 919                 ip->ip_off <<= 3;
 920
 921                 /*
 922                  * Attempt reassembly; if it succeeds, proceed.
 923                  * ip_reass() will return a different mbuf, and update
 924                  * the divert info in divert_info and args.divert_rule.
 925                  */
 926                 ipstat.ips_fragments++;
 927                 m->m_pkthdr.header = ip;
 928                 m = ip_reass(m, fp, &ipq[sum], &divert_info, &args.divert_rule);
 929                 if (m == NULL)
 930                         return;
 931                 ipstat.ips_reassembled++;
 932                 needredispatch = TRUE;
 933                 ip = mtod(m, struct ip *);
 934                 /* Get the header length of the reassembled packet */
 935                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 936 #ifdef IPDIVERT
 937                 /* Restore original checksum before diverting packet */
 938                 if (divert_info != 0) {
 939                         ip->ip_len += hlen;
 940                         ip->ip_len = htons(ip->ip_len);
 941                         ip->ip_off = htons(ip->ip_off);
 942                         ip->ip_sum = 0;
 943                         if (hlen == sizeof(struct ip))
 944                                 ip->ip_sum = in_cksum_hdr(ip);
 945                         else
 946                                 ip->ip_sum = in_cksum(m, hlen);
 947                         ip->ip_off = ntohs(ip->ip_off);
 948                         ip->ip_len = ntohs(ip->ip_len);
 949                         ip->ip_len -= hlen;
 950                 }
 951 #endif
 952         } else {
 953                 ip->ip_len -= hlen;
 954         }
 955
 956 #ifdef IPDIVERT
 957         /*
 958          * Divert or tee packet to the divert protocol if required.
 959          */
 960         if (divert_info != 0) {
 961                 struct mbuf *clone = NULL;
 962
 963                 /* Clone packet if we're doing a 'tee' */
 964                 if ((divert_info & IP_FW_PORT_TEE_FLAG) != 0)
 965                         clone = m_dup(m, MB_DONTWAIT);
 966
 967                 /* Restore packet header fields to original values */
 968                 ip->ip_len += hlen;
 969                 ip->ip_len = htons(ip->ip_len);
 970                 ip->ip_off = htons(ip->ip_off);
 971
 972                 /* Deliver packet to divert input routine */
 973                 divert_packet(m, 1, divert_info & 0xffff, args.divert_rule);
 974                 ipstat.ips_delivered++;
 975
 976                 /* If 'tee', continue with original packet */
 977                 if (clone == NULL)
 978                         return;
 979                 m = clone;
 980                 ip = mtod(m, struct ip *);
 981                 ip->ip_len += hlen;
 982                 /*
 983                  * Jump backwards to complete processing of the
 984                  * packet. But first clear divert_info to avoid
 985                  * entering this block again.
 986                  * We do not need to clear args.divert_rule
 987                  * or args.next_hop as they will not be used.
 988                  */
 989                 divert_info = 0;
 990                 goto pass;
 991         }
 992 #endif
 993
 994 #ifdef IPSEC
 995         /*
 996          * enforce IPsec policy checking if we are seeing last header.
 997          * note that we do not visit this with protocols with pcb layer
 998          * code - like udp/tcp/raw ip.
 999          */
1000         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) &&
1001             ipsec4_in_reject(m, NULL)) {
1002                 ipsecstat.in_polvio++;
1003                 goto bad;
1004         }
1005 #endif
1006 #if FAST_IPSEC
1007         /*
1008          * enforce IPsec policy checking if we are seeing last header.
1009          * note that we do not visit this with protocols with pcb layer
1010          * code - like udp/tcp/raw ip.
1011          */
1012         if (inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) {
1013                 /*
1014                  * Check if the packet has already had IPsec processing
1015                  * done.  If so, then just pass it along.  This tag gets
1016                  * set during AH, ESP, etc. input handling, before the
1017                  * packet is returned to the ip input queue for delivery.
1018                  */
1019                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
1020                 s = splnet();
1021                 if (mtag != NULL) {
1022                         tdbi = (struct tdb_ident *)(mtag + 1);
1023                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
1024                 } else {
1025                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
1026                                                    IP_FORWARDING, &error);
1027                 }
1028                 if (sp != NULL) {
1029                         /*
1030                          * Check security policy against packet attributes.
1031                          */
1032                         error = ipsec_in_reject(sp, m);
1033                         KEY_FREESP(&sp);
1034                 } else {
1035                         /* XXX error stat??? */
1036                         error = EINVAL;
1037 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
1038                         goto bad;
1039                 }
1040                 splx(s);
1041                 if (error)
1042                         goto bad;
1043         }
1044 #endif /* FAST_IPSEC */
1045
1046         ipstat.ips_delivered++;
1047         if (needredispatch) {
1048                 struct netmsg_transport_packet *msg;
1049                 lwkt_port_t port;
1050
1051                 msg = malloc(sizeof(struct netmsg_transport_packet),
1052                                 M_LWKTMSG, M_INTWAIT | M_NULLOK);
1053                 if (msg == NULL)
1054                         goto bad;
1055
1056                 lwkt_initmsg(&msg->nm_lmsg, &netisr_afree_rport, 0,
1057                         lwkt_cmd_func(transport_processing_handler),
1058                         lwkt_cmd_op_none);
1059                 msg->nm_mbuf = m;
1060                 msg->nm_hlen = hlen;
1061                 msg->nm_hasnexthop = (args.next_hop != NULL);
1062                 if (msg->nm_hasnexthop)
1063                         msg->nm_nexthop = *args.next_hop;  /* structure copy */
1064
1065                 ip->ip_off = htons(ip->ip_off);
1066                 ip->ip_len = htons(ip->ip_len);
1067                 port = ip_mport(m);
1068                 if (port == NULL)
1069                         goto bad;
1070                 ip->ip_len = ntohs(ip->ip_len);
1071                 ip->ip_off = ntohs(ip->ip_off);
1072
1073                 lwkt_sendmsg(port, &msg->nm_lmsg);
1074         } else {
1075                 transport_processing_oncpu(m, hlen, ip, args.next_hop);
1076         }
1077         return;
1078
1079 bad:
1080         m_freem(m);
1081 }
1082
1083 /*
1084  * Take incoming datagram fragment and try to reassemble it into
1085  * whole datagram.  If a chain for reassembly of this datagram already
1086  * exists, then it is given as fp; otherwise have to make a chain.
1087  *
1088  * When IPDIVERT enabled, keep additional state with each packet that
1089  * tells us if we need to divert or tee the packet we're building.
1090  * In particular, *divinfo includes the port and TEE flag,
1091  * *divert_rule is the number of the matching rule.
1092  */
1093
1094 static struct mbuf *
1095 ip_reass(struct mbuf *m, struct ipq *fp, struct ipq *where,
1096          u_int32_t *divinfo, u_int16_t *divert_rule)
1097 {
1098         struct ip *ip = mtod(m, struct ip *);
1099         struct mbuf *p = NULL, *q, *nq;
1100         struct mbuf *n;
1101         int hlen = IP_VHL_HL(ip->ip_vhl) << 2;
1102         int i, next;
1103
1104         /*
1105          * Presence of header sizes in mbufs
1106          * would confuse code below.
1107          */
1108         m->m_data += hlen;
1109         m->m_len -= hlen;
1110
1111         /*
1112          * If first fragment to arrive, create a reassembly queue.
1113          */
1114         if (fp == NULL) {
1115                 if ((fp = mpipe_alloc_nowait(&ipq_mpipe)) == NULL)
1116                         goto dropfrag;
1117                 insque(fp, where);
1118                 nipq++;
1119                 fp->ipq_nfrags = 1;
1120                 fp->ipq_ttl = IPFRAGTTL;
1121                 fp->ipq_p = ip->ip_p;
1122                 fp->ipq_id = ip->ip_id;
1123                 fp->ipq_src = ip->ip_src;
1124                 fp->ipq_dst = ip->ip_dst;
1125                 fp->ipq_frags = m;
1126                 m->m_nextpkt = NULL;
1127 #ifdef IPDIVERT
1128                 fp->ipq_div_info = 0;
1129                 fp->ipq_div_cookie = 0;
1130 #endif
1131                 goto inserted;
1132         } else {
1133                 fp->ipq_nfrags++;
1134         }
1135
1136 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.header))
1137
1138         /*
1139          * Find a segment which begins after this one does.
1140          */
1141         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
1142                 if (GETIP(q)->ip_off > ip->ip_off)
1143                         break;
1144
1145         /*
1146          * If there is a preceding segment, it may provide some of
1147          * our data already.  If so, drop the data from the incoming
1148          * segment.  If it provides all of our data, drop us, otherwise
1149          * stick new segment in the proper place.
1150          *
1151          * If some of the data is dropped from the the preceding
1152          * segment, then it's checksum is invalidated.
1153          */
1154         if (p) {
1155                 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
1156                 if (i > 0) {
1157                         if (i >= ip->ip_len)
1158                                 goto dropfrag;
1159                         m_adj(m, i);
1160                         m->m_pkthdr.csum_flags = 0;
1161                         ip->ip_off += i;
1162                         ip->ip_len -= i;
1163                 }
1164                 m->m_nextpkt = p->m_nextpkt;
1165                 p->m_nextpkt = m;
1166         } else {
1167                 m->m_nextpkt = fp->ipq_frags;
1168                 fp->ipq_frags = m;
1169         }
1170
1171         /*
1172          * While we overlap succeeding segments trim them or,
1173          * if they are completely covered, dequeue them.
1174          */
1175         for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
1176              q = nq) {
1177                 i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off;
1178                 if (i < GETIP(q)->ip_len) {
1179                         GETIP(q)->ip_len -= i;
1180                         GETIP(q)->ip_off += i;
1181                         m_adj(q, i);
1182                         q->m_pkthdr.csum_flags = 0;
1183                         break;
1184                 }
1185                 nq = q->m_nextpkt;
1186                 m->m_nextpkt = nq;
1187                 ipstat.ips_fragdropped++;
1188                 fp->ipq_nfrags--;
1189                 m_freem(q);
1190         }
1191
1192 inserted:
1193
1194 #ifdef IPDIVERT
1195         /*
1196          * Transfer firewall instructions to the fragment structure.
1197          * Only trust info in the fragment at offset 0.
1198          */
1199         if (ip->ip_off == 0) {
1200                 fp->ipq_div_info = *divinfo;
1201                 fp->ipq_div_cookie = *divert_rule;
1202         }
1203         *divinfo = 0;
1204         *divert_rule = 0;
1205 #endif
1206
1207         /*
1208          * Check for complete reassembly and perform frag per packet
1209          * limiting.
1210          *
1211          * Frag limiting is performed here so that the nth frag has
1212          * a chance to complete the packet before we drop the packet.
1213          * As a result, n+1 frags are actually allowed per packet, but
1214          * only n will ever be stored. (n = maxfragsperpacket.)
1215          *
1216          */
1217         next = 0;
1218         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
1219                 if (GETIP(q)->ip_off != next) {
1220                         if (fp->ipq_nfrags > maxfragsperpacket) {
1221                                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1222                                 ip_freef(fp);
1223                         }
1224                         return (NULL);
1225                 }
1226                 next += GETIP(q)->ip_len;
1227         }
1228         /* Make sure the last packet didn't have the IP_MF flag */
1229         if (p->m_flags & M_FRAG) {
1230                 if (fp->ipq_nfrags > maxfragsperpacket) {
1231                         ipstat.ips_fragdropped += fp->ipq_nfrags;
1232                         ip_freef(fp);
1233                 }
1234                 return (NULL);
1235         }
1236
1237         /*
1238          * Reassembly is complete.  Make sure the packet is a sane size.
1239          */
1240         q = fp->ipq_frags;
1241         ip = GETIP(q);
1242         if (next + (IP_VHL_HL(ip->ip_vhl) << 2) > IP_MAXPACKET) {
1243                 ipstat.ips_toolong++;
1244                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1245                 ip_freef(fp);
1246                 return (NULL);
1247         }
1248
1249         /*
1250          * Concatenate fragments.
1251          */
1252         m = q;
1253         n = m->m_next;
1254         m->m_next = NULL;
1255         m_cat(m, n);
1256         nq = q->m_nextpkt;
1257         q->m_nextpkt = NULL;
1258         for (q = nq; q != NULL; q = nq) {
1259                 nq = q->m_nextpkt;
1260                 q->m_nextpkt = NULL;
1261                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
1262                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
1263                 m_cat(m, q);
1264         }
1265
1266 #ifdef IPDIVERT
1267         /*
1268          * Extract firewall instructions from the fragment structure.
1269          */
1270         *divinfo = fp->ipq_div_info;
1271         *divert_rule = fp->ipq_div_cookie;
1272 #endif
1273
1274         /*
1275          * Create header for new ip packet by
1276          * modifying header of first packet;
1277          * dequeue and discard fragment reassembly header.
1278          * Make header visible.
1279          */
1280         ip->ip_len = next;
1281         ip->ip_src = fp->ipq_src;
1282         ip->ip_dst = fp->ipq_dst;
1283         remque(fp);
1284         nipq--;
1285         mpipe_free(&ipq_mpipe, fp);
1286         m->m_len += (IP_VHL_HL(ip->ip_vhl) << 2);
1287         m->m_data -= (IP_VHL_HL(ip->ip_vhl) << 2);
1288         /* some debugging cruft by sklower, below, will go away soon */
1289         if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
1290                 int plen = 0;
1291
1292                 for (n = m; n; n = n->m_next)
1293                         plen += n->m_len;
1294                 m->m_pkthdr.len = plen;
1295         }
1296         return (m);
1297
1298 dropfrag:
1299 #ifdef IPDIVERT
1300         *divinfo = 0;
1301         *divert_rule = 0;
1302 #endif
1303         ipstat.ips_fragdropped++;
1304         if (fp != NULL)
1305                 fp->ipq_nfrags--;
1306         m_freem(m);
1307         return (NULL);
1308
1309 #undef GETIP
1310 }
1311
1312 /*
1313  * Free a fragment reassembly header and all
1314  * associated datagrams.
1315  */
1316 static void
1317 ip_freef(struct ipq *fp)
1318 {
1319         struct mbuf *q;
1320
1321         while (fp->ipq_frags) {
1322                 q = fp->ipq_frags;
1323                 fp->ipq_frags = q->m_nextpkt;
1324                 m_freem(q);
1325         }
1326         remque(fp);
1327         mpipe_free(&ipq_mpipe, fp);
1328         nipq--;
1329 }
1330
1331 /*
1332  * IP timer processing;
1333  * if a timer expires on a reassembly
1334  * queue, discard it.
1335  */
1336 void
1337 ip_slowtimo(void)
1338 {
1339         struct ipq *fp;
1340         int s = splnet();
1341         int i;
1342
1343         for (i = 0; i < IPREASS_NHASH; i++) {
1344                 fp = ipq[i].next;
1345                 if (fp == NULL)
1346                         continue;
1347                 while (fp != &ipq[i]) {
1348                         --fp->ipq_ttl;
1349                         fp = fp->next;
1350                         if (fp->prev->ipq_ttl == 0) {
1351                                 ipstat.ips_fragtimeout += fp->prev->ipq_nfrags;
1352                                 ip_freef(fp->prev);
1353                         }
1354                 }
1355         }
1356         /*
1357          * If we are over the maximum number of fragments
1358          * (due to the limit being lowered), drain off
1359          * enough to get down to the new limit.
1360          */
1361         if (maxnipq >= 0 && nipq > maxnipq) {
1362                 for (i = 0; i < IPREASS_NHASH; i++) {
1363                         while (nipq > maxnipq &&
1364                                 (ipq[i].next != &ipq[i])) {
1365                                 ipstat.ips_fragdropped +=
1366                                     ipq[i].next->ipq_nfrags;
1367                                 ip_freef(ipq[i].next);
1368                         }
1369                 }
1370         }
1371         ipflow_slowtimo();
1372         splx(s);
1373 }
1374
1375 /*
1376  * Drain off all datagram fragments.
1377  */
1378 void
1379 ip_drain(void)
1380 {
1381         int i;
1382
1383         for (i = 0; i < IPREASS_NHASH; i++) {
1384                 while (ipq[i].next != &ipq[i]) {
1385                         ipstat.ips_fragdropped += ipq[i].next->ipq_nfrags;
1386                         ip_freef(ipq[i].next);
1387                 }
1388         }
1389         in_rtqdrain();
1390 }
1391
1392 /*
1393  * Do option processing on a datagram,
1394  * possibly discarding it if bad options are encountered,
1395  * or forwarding it if source-routed.
1396  * The pass argument is used when operating in the IPSTEALTH
1397  * mode to tell what options to process:
1398  * [LS]SRR (pass 0) or the others (pass 1).
1399  * The reason for as many as two passes is that when doing IPSTEALTH,
1400  * non-routing options should be processed only if the packet is for us.
1401  * Returns 1 if packet has been forwarded/freed,
1402  * 0 if the packet should be processed further.
1403  */
1404 static int
1405 ip_dooptions(struct mbuf *m, int pass, struct sockaddr_in *next_hop)
1406 {
1407         struct ip *ip = mtod(m, struct ip *);
1408         u_char *cp;
1409         struct in_ifaddr *ia;
1410         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB;
1411         boolean_t forward = FALSE;
1412         struct in_addr *sin, dst;
1413         n_time ntime;
1414
1415         dst = ip->ip_dst;
1416         cp = (u_char *)(ip + 1);
1417         cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
1418         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1419                 opt = cp[IPOPT_OPTVAL];
1420                 if (opt == IPOPT_EOL)
1421                         break;
1422                 if (opt == IPOPT_NOP)
1423                         optlen = 1;
1424                 else {
1425                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
1426                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1427                                 goto bad;
1428                         }
1429                         optlen = cp[IPOPT_OLEN];
1430                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
1431                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1432                                 goto bad;
1433                         }
1434                 }
1435                 switch (opt) {
1436
1437                 default:
1438                         break;
1439
1440                 /*
1441                  * Source routing with record.
1442                  * Find interface with current destination address.
1443                  * If none on this machine then drop if strictly routed,
1444                  * or do nothing if loosely routed.
1445                  * Record interface address and bring up next address
1446                  * component.  If strictly routed make sure next
1447                  * address is on directly accessible net.
1448                  */
1449                 case IPOPT_LSRR:
1450                 case IPOPT_SSRR:
1451                         if (ipstealth && pass > 0)
1452                                 break;
1453                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1454                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1455                                 goto bad;
1456                         }
1457                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1458                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1459                                 goto bad;
1460                         }
1461                         ipaddr.sin_addr = ip->ip_dst;
1462                         ia = (struct in_ifaddr *)
1463                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
1464                         if (ia == NULL) {
1465                                 if (opt == IPOPT_SSRR) {
1466                                         type = ICMP_UNREACH;
1467                                         code = ICMP_UNREACH_SRCFAIL;
1468                                         goto bad;
1469                                 }
1470                                 if (!ip_dosourceroute)
1471                                         goto nosourcerouting;
1472                                 /*
1473                                  * Loose routing, and not at next destination
1474                                  * yet; nothing to do except forward.
1475                                  */
1476                                 break;
1477                         }
1478                         off--;                  /* 0 origin */
1479                         if (off > optlen - (int)sizeof(struct in_addr)) {
1480                                 /*
1481                                  * End of source route.  Should be for us.
1482                                  */
1483                                 if (!ip_acceptsourceroute)
1484                                         goto nosourcerouting;
1485                                 save_rte(cp, ip->ip_src);
1486                                 break;
1487                         }
1488                         if (ipstealth)
1489                                 goto dropit;
1490                         if (!ip_dosourceroute) {
1491                                 if (ipforwarding) {
1492                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
1493                                         /*
1494                                          * Acting as a router, so generate ICMP
1495                                          */
1496 nosourcerouting:
1497                                         strcpy(buf, inet_ntoa(ip->ip_dst));
1498                                         log(LOG_WARNING,
1499                                             "attempted source route from %s to %s\n",
1500                                             inet_ntoa(ip->ip_src), buf);
1501                                         type = ICMP_UNREACH;
1502                                         code = ICMP_UNREACH_SRCFAIL;
1503                                         goto bad;
1504                                 } else {
1505                                         /*
1506                                          * Not acting as a router,
1507                                          * so silently drop.
1508                                          */
1509 dropit:
1510                                         ipstat.ips_cantforward++;
1511                                         m_freem(m);
1512                                         return (1);
1513                                 }
1514                         }
1515
1516                         /*
1517                          * locate outgoing interface
1518                          */
1519                         (void)memcpy(&ipaddr.sin_addr, cp + off,
1520                             sizeof(ipaddr.sin_addr));
1521
1522                         if (opt == IPOPT_SSRR) {
1523 #define INA     struct in_ifaddr *
1524 #define SA      struct sockaddr *
1525                                 if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr))
1526                                                                         == NULL)
1527                                         ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1528                         } else
1529                                 ia = ip_rtaddr(ipaddr.sin_addr, &ipforward_rt);
1530                         if (ia == NULL) {
1531                                 type = ICMP_UNREACH;
1532                                 code = ICMP_UNREACH_SRCFAIL;
1533                                 goto bad;
1534                         }
1535                         ip->ip_dst = ipaddr.sin_addr;
1536                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1537                             sizeof(struct in_addr));
1538                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1539                         /*
1540                          * Let ip_intr's mcast routing check handle mcast pkts
1541                          */
1542                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
1543                         break;
1544
1545                 case IPOPT_RR:
1546                         if (ipstealth && pass == 0)
1547                                 break;
1548                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1549                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1550                                 goto bad;
1551                         }
1552                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1553                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1554                                 goto bad;
1555                         }
1556                         /*
1557                          * If no space remains, ignore.
1558                          */
1559                         off--;                  /* 0 origin */
1560                         if (off > optlen - (int)sizeof(struct in_addr))
1561                                 break;
1562                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
1563                             sizeof(ipaddr.sin_addr));
1564                         /*
1565                          * locate outgoing interface; if we're the destination,
1566                          * use the incoming interface (should be same).
1567                          */
1568                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
1569                             (ia = ip_rtaddr(ipaddr.sin_addr, &ipforward_rt))
1570                                                                      == NULL) {
1571                                 type = ICMP_UNREACH;
1572                                 code = ICMP_UNREACH_HOST;
1573                                 goto bad;
1574                         }
1575                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1576                             sizeof(struct in_addr));
1577                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1578                         break;
1579
1580                 case IPOPT_TS:
1581                         if (ipstealth && pass == 0)
1582                                 break;
1583                         code = cp - (u_char *)ip;
1584                         if (optlen < 4 || optlen > 40) {
1585                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1586                                 goto bad;
1587                         }
1588                         if ((off = cp[IPOPT_OFFSET]) < 5) {
1589                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1590                                 goto bad;
1591                         }
1592                         if (off > optlen - (int)sizeof(int32_t)) {
1593                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
1594                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
1595                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1596                                         goto bad;
1597                                 }
1598                                 break;
1599                         }
1600                         off--;                          /* 0 origin */
1601                         sin = (struct in_addr *)(cp + off);
1602                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
1603
1604                         case IPOPT_TS_TSONLY:
1605                                 break;
1606
1607                         case IPOPT_TS_TSANDADDR:
1608                                 if (off + sizeof(n_time) +
1609                                     sizeof(struct in_addr) > optlen) {
1610                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1611                                         goto bad;
1612                                 }
1613                                 ipaddr.sin_addr = dst;
1614                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
1615                                                             m->m_pkthdr.rcvif);
1616                                 if (ia == NULL)
1617                                         continue;
1618                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
1619                                     sizeof(struct in_addr));
1620                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1621                                 off += sizeof(struct in_addr);
1622                                 break;
1623
1624                         case IPOPT_TS_PRESPEC:
1625                                 if (off + sizeof(n_time) +
1626                                     sizeof(struct in_addr) > optlen) {
1627                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1628                                         goto bad;
1629                                 }
1630                                 (void)memcpy(&ipaddr.sin_addr, sin,
1631                                     sizeof(struct in_addr));
1632                                 if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
1633                                         continue;
1634                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1635                                 off += sizeof(struct in_addr);
1636                                 break;
1637
1638                         default:
1639                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
1640                                 goto bad;
1641                         }
1642                         ntime = iptime();
1643                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
1644                         cp[IPOPT_OFFSET] += sizeof(n_time);
1645                 }
1646         }
1647         if (forward && ipforwarding) {
1648                 ip_forward(m, 1, next_hop);
1649                 return (1);
1650         }
1651         return (0);
1652 bad:
1653         icmp_error(m, type, code, 0, NULL);
1654         ipstat.ips_badoptions++;
1655         return (1);
1656 }
1657
1658 /*
1659  * Given address of next destination (final or next hop),
1660  * return internet address info of interface to be used to get there.
1661  */
1662 struct in_ifaddr *
1663 ip_rtaddr(struct in_addr dst, struct route *rt)
1664 {
1665         struct sockaddr_in *sin;
1666
1667         sin = (struct sockaddr_in *)&rt->ro_dst;
1668
1669         if (rt->ro_rt == NULL || dst.s_addr != sin->sin_addr.s_addr) {
1670                 if (rt->ro_rt != NULL) {
1671                         RTFREE(rt->ro_rt);
1672                         rt->ro_rt = NULL;
1673                 }
1674                 sin->sin_family = AF_INET;
1675                 sin->sin_len = sizeof(*sin);
1676                 sin->sin_addr = dst;
1677                 rtalloc_ign(rt, RTF_PRCLONING);
1678         }
1679
1680         if (rt->ro_rt == NULL)
1681                 return (NULL);
1682
1683         return (ifatoia(rt->ro_rt->rt_ifa));
1684 }
1685
1686 /*
1687  * Save incoming source route for use in replies,
1688  * to be picked up later by ip_srcroute if the receiver is interested.
1689  */
1690 void
1691 save_rte(u_char *option, struct in_addr dst)
1692 {
1693         unsigned olen;
1694
1695         olen = option[IPOPT_OLEN];
1696 #ifdef DIAGNOSTIC
1697         if (ipprintfs)
1698                 printf("save_rte: olen %d\n", olen);
1699 #endif
1700         if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
1701                 return;
1702         bcopy(option, ip_srcrt.srcopt, olen);
1703         ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1704         ip_srcrt.dst = dst;
1705 }
1706
1707 /*
1708  * Retrieve incoming source route for use in replies,
1709  * in the same form used by setsockopt.
1710  * The first hop is placed before the options, will be removed later.
1711  */
1712 struct mbuf *
1713 ip_srcroute(void)
1714 {
1715         struct in_addr *p, *q;
1716         struct mbuf *m;
1717
1718         if (ip_nhops == 0)
1719                 return (NULL);
1720         m = m_get(MB_DONTWAIT, MT_HEADER);
1721         if (m == NULL)
1722                 return (NULL);
1723
1724 #define OPTSIZ  (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1725
1726         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1727         m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
1728             OPTSIZ;
1729 #ifdef DIAGNOSTIC
1730         if (ipprintfs)
1731                 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1732 #endif
1733
1734         /*
1735          * First save first hop for return route
1736          */
1737         p = &ip_srcrt.route[ip_nhops - 1];
1738         *(mtod(m, struct in_addr *)) = *p--;
1739 #ifdef DIAGNOSTIC
1740         if (ipprintfs)
1741                 printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
1742 #endif
1743
1744         /*
1745          * Copy option fields and padding (nop) to mbuf.
1746          */
1747         ip_srcrt.nop = IPOPT_NOP;
1748         ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1749         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), &ip_srcrt.nop,
1750             OPTSIZ);
1751         q = (struct in_addr *)(mtod(m, caddr_t) +
1752             sizeof(struct in_addr) + OPTSIZ);
1753 #undef OPTSIZ
1754         /*
1755          * Record return path as an IP source route,
1756          * reversing the path (pointers are now aligned).
1757          */
1758         while (p >= ip_srcrt.route) {
1759 #ifdef DIAGNOSTIC
1760                 if (ipprintfs)
1761                         printf(" %lx", ntohl(q->s_addr));
1762 #endif
1763                 *q++ = *p--;
1764         }
1765         /*
1766          * Last hop goes to final destination.
1767          */
1768         *q = ip_srcrt.dst;
1769 #ifdef DIAGNOSTIC
1770         if (ipprintfs)
1771                 printf(" %lx\n", ntohl(q->s_addr));
1772 #endif
1773         return (m);
1774 }
1775
1776 /*
1777  * Strip out IP options.
1778  */
1779 void
1780 ip_stripoptions(struct mbuf *m)
1781 {
1782         int datalen;
1783         struct ip *ip = mtod(m, struct ip *);
1784         caddr_t opts;
1785         int optlen;
1786
1787         optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
1788         opts = (caddr_t)(ip + 1);
1789         datalen = m->m_len - (sizeof(struct ip) + optlen);
1790         bcopy(opts + optlen, opts, datalen);
1791         m->m_len -= optlen;
1792         if (m->m_flags & M_PKTHDR)
1793                 m->m_pkthdr.len -= optlen;
1794         ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2);
1795 }
1796
1797 u_char inetctlerrmap[PRC_NCMDS] = {
1798         0,              0,              0,              0,
1799         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
1800         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
1801         EMSGSIZE,       EHOSTUNREACH,   0,              0,
1802         0,              0,              0,              0,
1803         ENOPROTOOPT,    ECONNREFUSED
1804 };
1805
1806 /*
1807  * Forward a packet.  If some error occurs return the sender
1808  * an icmp packet.  Note we can't always generate a meaningful
1809  * icmp message because icmp doesn't have a large enough repertoire
1810  * of codes and types.
1811  *
1812  * If not forwarding, just drop the packet.  This could be confusing
1813  * if ipforwarding was zero but some routing protocol was advancing
1814  * us as a gateway to somewhere.  However, we must let the routing
1815  * protocol deal with that.
1816  *
1817  * The using_srcrt parameter indicates whether the packet is being forwarded
1818  * via a source route.
1819  */
1820 static void
1821 ip_forward(struct mbuf *m, int using_srcrt, struct sockaddr_in *next_hop)
1822 {
1823         struct ip *ip = mtod(m, struct ip *);
1824         struct sockaddr_in *sin;
1825         struct rtentry *rt;
1826         int error, type = 0, code = 0;
1827         struct mbuf *mcopy;
1828         n_long dest;
1829         struct in_addr pkt_dst;
1830         struct ifnet *destifp;
1831         struct m_hdr tag;
1832 #if defined(IPSEC) || defined(FAST_IPSEC)
1833         struct ifnet dummyifp;
1834 #endif
1835
1836         dest = 0;
1837         /*
1838          * Cache the destination address of the packet; this may be
1839          * changed by use of 'ipfw fwd'.
1840          */
1841         pkt_dst = next_hop ? next_hop->sin_addr : ip->ip_dst;
1842
1843 #ifdef DIAGNOSTIC
1844         if (ipprintfs)
1845                 printf("forward: src %x dst %x ttl %x\n",
1846                        ip->ip_src.s_addr, pkt_dst.s_addr, ip->ip_ttl);
1847 #endif
1848
1849         if (m->m_flags & (M_BCAST | M_MCAST) || !in_canforward(pkt_dst)) {
1850                 ipstat.ips_cantforward++;
1851                 m_freem(m);
1852                 return;
1853         }
1854         if (!ipstealth && ip->ip_ttl <= IPTTLDEC) {
1855                 icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, NULL);
1856                 return;
1857         }
1858
1859         sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
1860         if ((rt = ipforward_rt.ro_rt) == NULL ||
1861             pkt_dst.s_addr != sin->sin_addr.s_addr) {
1862                 if (ipforward_rt.ro_rt != NULL) {
1863                         RTFREE(ipforward_rt.ro_rt);
1864                         ipforward_rt.ro_rt = NULL;
1865                 }
1866                 sin->sin_family = AF_INET;
1867                 sin->sin_len = sizeof(*sin);
1868                 sin->sin_addr = pkt_dst;
1869
1870                 rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
1871                 if (ipforward_rt.ro_rt == NULL) {
1872                         icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest,
1873                                    NULL);
1874                         return;
1875                 }
1876                 rt = ipforward_rt.ro_rt;
1877         }
1878
1879         /*
1880          * Save the IP header and at most 8 bytes of the payload,
1881          * in case we need to generate an ICMP message to the src.
1882          *
1883          * XXX this can be optimized a lot by saving the data in a local
1884          * buffer on the stack (72 bytes at most), and only allocating the
1885          * mbuf if really necessary. The vast majority of the packets
1886          * are forwarded without having to send an ICMP back (either
1887          * because unnecessary, or because rate limited), so we are
1888          * really we are wasting a lot of work here.
1889          *
1890          * We don't use m_copy() because it might return a reference
1891          * to a shared cluster. Both this function and ip_output()
1892          * assume exclusive access to the IP header in `m', so any
1893          * data in a cluster may change before we reach icmp_error().
1894          */
1895         MGET(mcopy, MB_DONTWAIT, m->m_type);
1896         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, MB_DONTWAIT)) {
1897                 /*
1898                  * It's probably ok if the pkthdr dup fails (because
1899                  * the deep copy of the tag chain failed), but for now
1900                  * be conservative and just discard the copy since
1901                  * code below may some day want the tags.
1902                  */
1903                 m_free(mcopy);
1904                 mcopy = NULL;
1905         }
1906         if (mcopy != NULL) {
1907                 mcopy->m_len = imin((IP_VHL_HL(ip->ip_vhl) << 2) + 8,
1908                     (int)ip->ip_len);
1909                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
1910         }
1911
1912         if (!ipstealth)
1913                 ip->ip_ttl -= IPTTLDEC;
1914
1915         /*
1916          * If forwarding packet using same interface that it came in on,
1917          * perhaps should send a redirect to sender to shortcut a hop.
1918          * Only send redirect if source is sending directly to us,
1919          * and if packet was not source routed (or has any options).
1920          * Also, don't send redirect if forwarding using a default route
1921          * or a route modified by a redirect.
1922          */
1923         if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1924             !(rt->rt_flags & (RTF_DYNAMIC | RTF_MODIFIED)) &&
1925             satosin(rt_key(rt))->sin_addr.s_addr != INADDR_ANY &&
1926             ipsendredirects && !using_srcrt && next_hop != NULL) {
1927                 u_long src = ntohl(ip->ip_src.s_addr);
1928
1929 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1930                 if (RTA(rt) != NULL &&
1931                     (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1932                         if (rt->rt_flags & RTF_GATEWAY)
1933                                 dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1934                         else
1935                                 dest = pkt_dst.s_addr;
1936                         /*
1937                          * Router requirements says to only send
1938                          * host redirects.
1939                          */
1940                         type = ICMP_REDIRECT;
1941                         code = ICMP_REDIRECT_HOST;
1942 #ifdef DIAGNOSTIC
1943                         if (ipprintfs)
1944                                 printf("redirect (%d) to %x\n", code, dest);
1945 #endif
1946                 }
1947         }
1948
1949         if (next_hop) {
1950                 /* Pass IPFORWARD info if available */
1951                 tag.mh_type = MT_TAG;
1952                 tag.mh_flags = PACKET_TAG_IPFORWARD;
1953                 tag.mh_data = (caddr_t)next_hop;
1954                 tag.mh_next = m;
1955                 m = (struct mbuf *)&tag;
1956         }
1957
1958         error = ip_output(m, NULL, &ipforward_rt, IP_FORWARDING, NULL, NULL);
1959
1960         if (error)
1961                 ipstat.ips_cantforward++;
1962         else {
1963                 ipstat.ips_forward++;
1964                 if (type)
1965                         ipstat.ips_redirectsent++;
1966                 else {
1967                         if (mcopy) {
1968                                 ipflow_create(&ipforward_rt, mcopy);
1969                                 m_freem(mcopy);
1970                         }
1971                         return;
1972                 }
1973         }
1974         if (mcopy == NULL)
1975                 return;
1976         destifp = NULL;
1977
1978         switch (error) {
1979
1980         case 0:                         /* forwarded, but need redirect */
1981                 /* type, code set above */
1982                 break;
1983
1984         case ENETUNREACH:               /* shouldn't happen, checked above */
1985         case EHOSTUNREACH:
1986         case ENETDOWN:
1987         case EHOSTDOWN:
1988         default:
1989                 type = ICMP_UNREACH;
1990                 code = ICMP_UNREACH_HOST;
1991                 break;
1992
1993         case EMSGSIZE:
1994                 type = ICMP_UNREACH;
1995                 code = ICMP_UNREACH_NEEDFRAG;
1996 #ifdef IPSEC
1997                 /*
1998                  * If the packet is routed over IPsec tunnel, tell the
1999                  * originator the tunnel MTU.
2000                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
2001                  * XXX quickhack!!!
2002                  */
2003                 if (ipforward_rt.ro_rt != NULL) {
2004                         struct secpolicy *sp = NULL;
2005                         int ipsecerror;
2006                         int ipsechdr;
2007                         struct route *ro;
2008
2009                         sp = ipsec4_getpolicybyaddr(mcopy,
2010                                                     IPSEC_DIR_OUTBOUND,
2011                                                     IP_FORWARDING,
2012                                                     &ipsecerror);
2013
2014                         if (sp == NULL)
2015                                 destifp = ipforward_rt.ro_rt->rt_ifp;
2016                         else {
2017                                 /* count IPsec header size */
2018                                 ipsechdr = ipsec4_hdrsiz(mcopy,
2019                                                          IPSEC_DIR_OUTBOUND,
2020                                                          NULL);
2021
2022                                 /*
2023                                  * find the correct route for outer IPv4
2024                                  * header, compute tunnel MTU.
2025                                  *
2026                                  * XXX BUG ALERT
2027                                  * The "dummyifp" code relies upon the fact
2028                                  * that icmp_error() touches only ifp->if_mtu.
2029                                  */
2030                                 /*XXX*/
2031                                 destifp = NULL;
2032                                 if (sp->req != NULL && sp->req->sav != NULL &&
2033                                     sp->req->sav->sah != NULL) {
2034                                         ro = &sp->req->sav->sah->sa_route;
2035                                         if (ro->ro_rt != NULL &&
2036                                             ro->ro_rt->rt_ifp != NULL) {
2037                                                 dummyifp.if_mtu =
2038                                                     ro->ro_rt->rt_ifp->if_mtu;
2039                                                 dummyifp.if_mtu -= ipsechdr;
2040                                                 destifp = &dummyifp;
2041                                         }
2042                                 }
2043
2044                                 key_freesp(sp);
2045                         }
2046                 }
2047 #elif FAST_IPSEC
2048                 /*
2049                  * If the packet is routed over IPsec tunnel, tell the
2050                  * originator the tunnel MTU.
2051                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
2052                  * XXX quickhack!!!
2053                  */
2054                 if (ipforward_rt.ro_rt != NULL) {
2055                         struct secpolicy *sp = NULL;
2056                         int ipsecerror;
2057                         int ipsechdr;
2058                         struct route *ro;
2059
2060                         sp = ipsec_getpolicybyaddr(mcopy,
2061                                                    IPSEC_DIR_OUTBOUND,
2062                                                    IP_FORWARDING,
2063                                                    &ipsecerror);
2064
2065                         if (sp == NULL)
2066                                 destifp = ipforward_rt.ro_rt->rt_ifp;
2067                         else {
2068                                 /* count IPsec header size */
2069                                 ipsechdr = ipsec4_hdrsiz(mcopy,
2070                                                          IPSEC_DIR_OUTBOUND,
2071                                                          NULL);
2072
2073                                 /*
2074                                  * find the correct route for outer IPv4
2075                                  * header, compute tunnel MTU.
2076                                  *
2077                                  * XXX BUG ALERT
2078                                  * The "dummyifp" code relies upon the fact
2079                                  * that icmp_error() touches only ifp->if_mtu.
2080                                  */
2081                                 /*XXX*/
2082                                 destifp = NULL;
2083                                 if (sp->req != NULL &&
2084                                     sp->req->sav != NULL &&
2085                                     sp->req->sav->sah != NULL) {
2086                                         ro = &sp->req->sav->sah->sa_route;
2087                                         if (ro->ro_rt != NULL &&
2088                                             ro->ro_rt->rt_ifp != NULL) {
2089                                                 dummyifp.if_mtu =
2090                                                     ro->ro_rt->rt_ifp->if_mtu;
2091                                                 dummyifp.if_mtu -= ipsechdr;
2092                                                 destifp = &dummyifp;
2093                                         }
2094                                 }
2095
2096                                 KEY_FREESP(&sp);
2097                         }
2098                 }
2099 #else /* !IPSEC && !FAST_IPSEC */
2100                 if (ipforward_rt.ro_rt != NULL)
2101                         destifp = ipforward_rt.ro_rt->rt_ifp;
2102 #endif /*IPSEC*/
2103                 ipstat.ips_cantfrag++;
2104                 break;
2105
2106         case ENOBUFS:
2107                 /*
2108                  * A router should not generate ICMP_SOURCEQUENCH as
2109                  * required in RFC1812 Requirements for IP Version 4 Routers.
2110                  * Source quench could be a big problem under DoS attacks,
2111                  * or if the underlying interface is rate-limited.
2112                  * Those who need source quench packets may re-enable them
2113                  * via the net.inet.ip.sendsourcequench sysctl.
2114                  */
2115                 if (!ip_sendsourcequench) {
2116                         m_freem(mcopy);
2117                         return;
2118                 } else {
2119                         type = ICMP_SOURCEQUENCH;
2120                         code = 0;
2121                 }
2122                 break;
2123
2124         case EACCES:                    /* ipfw denied packet */
2125                 m_freem(mcopy);
2126                 return;
2127         }
2128         icmp_error(mcopy, type, code, dest, destifp);
2129 }
2130
2131 void
2132 ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
2133                struct mbuf *m)
2134 {
2135         if (inp->inp_socket->so_options & SO_TIMESTAMP) {
2136                 struct timeval tv;
2137
2138                 microtime(&tv);
2139                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
2140                     SCM_TIMESTAMP, SOL_SOCKET);
2141                 if (*mp)
2142                         mp = &(*mp)->m_next;
2143         }
2144         if (inp->inp_flags & INP_RECVDSTADDR) {
2145                 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
2146                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
2147                 if (*mp)
2148                         mp = &(*mp)->m_next;
2149         }
2150 #ifdef notyet
2151         /* XXX
2152          * Moving these out of udp_input() made them even more broken
2153          * than they already were.
2154          */
2155         /* options were tossed already */
2156         if (inp->inp_flags & INP_RECVOPTS) {
2157                 *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
2158                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
2159                 if (*mp)
2160                         mp = &(*mp)->m_next;
2161         }
2162         /* ip_srcroute doesn't do what we want here, need to fix */
2163         if (inp->inp_flags & INP_RECVRETOPTS) {
2164                 *mp = sbcreatecontrol((caddr_t) ip_srcroute(),
2165                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
2166                 if (*mp)
2167                         mp = &(*mp)->m_next;
2168         }
2169 #endif
2170         if (inp->inp_flags & INP_RECVIF) {
2171                 struct ifnet *ifp;
2172                 struct sdlbuf {
2173                         struct sockaddr_dl sdl;
2174                         u_char  pad[32];
2175                 } sdlbuf;
2176                 struct sockaddr_dl *sdp;
2177                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
2178
2179                 if (((ifp = m->m_pkthdr.rcvif)) &&
2180                     ((ifp->if_index != 0) && (ifp->if_index <= if_index))) {
2181                         sdp = (struct sockaddr_dl *)
2182                             ifnet_addrs[ifp->if_index - 1]->ifa_addr;
2183                         /*
2184                          * Change our mind and don't try copy.
2185                          */
2186                         if ((sdp->sdl_family != AF_LINK) ||
2187                             (sdp->sdl_len > sizeof(sdlbuf))) {
2188                                 goto makedummy;
2189                         }
2190                         bcopy(sdp, sdl2, sdp->sdl_len);
2191                 } else {
2192 makedummy:
2193                         sdl2->sdl_len =
2194                             offsetof(struct sockaddr_dl, sdl_data[0]);
2195                         sdl2->sdl_family = AF_LINK;
2196                         sdl2->sdl_index = 0;
2197                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
2198                 }
2199                 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
2200                         IP_RECVIF, IPPROTO_IP);
2201                 if (*mp)
2202                         mp = &(*mp)->m_next;
2203         }
2204 }
2205
2206 /*
2207  * XXX these routines are called from the upper part of the kernel.
2208  *
2209  * They could also be moved to ip_mroute.c, since all the RSVP
2210  *  handling is done there already.
2211  */
2212 int
2213 ip_rsvp_init(struct socket *so)
2214 {
2215         if (so->so_type != SOCK_RAW ||
2216             so->so_proto->pr_protocol != IPPROTO_RSVP)
2217                 return EOPNOTSUPP;
2218
2219         if (ip_rsvpd != NULL)
2220                 return EADDRINUSE;
2221
2222         ip_rsvpd = so;
2223         /*
2224          * This may seem silly, but we need to be sure we don't over-increment
2225          * the RSVP counter, in case something slips up.
2226          */
2227         if (!ip_rsvp_on) {
2228                 ip_rsvp_on = 1;
2229                 rsvp_on++;
2230         }
2231
2232         return 0;
2233 }
2234
2235 int
2236 ip_rsvp_done(void)
2237 {
2238         ip_rsvpd = NULL;
2239         /*
2240          * This may seem silly, but we need to be sure we don't over-decrement
2241          * the RSVP counter, in case something slips up.
2242          */
2243         if (ip_rsvp_on) {
2244                 ip_rsvp_on = 0;
2245                 rsvp_on--;
2246         }
2247         return 0;
2248 }
2249
2250 void
2251 rsvp_input(struct mbuf *m, ...) /* XXX must fixup manually */
2252 {
2253         int off, proto;
2254         __va_list ap;
2255
2256         __va_start(ap, m);
2257         off = __va_arg(ap, int);
2258         proto = __va_arg(ap, int);
2259         __va_end(ap);
2260
2261         if (rsvp_input_p) { /* call the real one if loaded */
2262                 rsvp_input_p(m, off, proto);
2263                 return;
2264         }
2265
2266         /* Can still get packets with rsvp_on = 0 if there is a local member
2267          * of the group to which the RSVP packet is addressed.  But in this
2268          * case we want to throw the packet away.
2269          */
2270
2271         if (!rsvp_on) {
2272                 m_freem(m);
2273                 return;
2274         }
2275
2276         if (ip_rsvpd != NULL) {
2277                 rip_input(m, off, proto);
2278                 return;
2279         }
2280         /* Drop the packet */
2281         m_freem(m);
2282 }