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 1.12 2004/03/06 07:30:43 hsu 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/domain.h>
  55 #include <sys/protosw.h>
  56 #include <sys/socket.h>
  57 #include <sys/time.h>
  58 #include <sys/kernel.h>
  59 #include <sys/syslog.h>
  60 #include <sys/sysctl.h>
  61 #include <sys/in_cksum.h>
  62
  63 #include <net/if.h>
  64 #include <net/if_types.h>
  65 #include <net/if_var.h>
  66 #include <net/if_dl.h>
  67 #ifdef PFIL_HOOKS
  68 #include <net/pfil.h>
  69 #endif
  70 #include <net/route.h>
  71 #include <net/netisr.h>
  72 #include <net/intrq.h>
  73
  74 #include <netinet/in.h>
  75 #include <netinet/in_systm.h>
  76 #include <netinet/in_var.h>
  77 #include <netinet/ip.h>
  78 #include <netinet/in_pcb.h>
  79 #include <netinet/ip_var.h>
  80 #include <netinet/ip_icmp.h>
  81
  82 #include <netinet/ipprotosw.h>
  83
  84 #include <sys/socketvar.h>
  85
  86 #include <net/ipfw/ip_fw.h>
  87 #include <net/dummynet/ip_dummynet.h>
  88
  89 #ifdef IPSEC
  90 #include <netinet6/ipsec.h>
  91 #include <netproto/key/key.h>
  92 #endif
  93
  94 #ifdef FAST_IPSEC
  95 #include <netipsec/ipsec.h>
  96 #include <netipsec/key.h>
  97 #endif
  98
  99 int rsvp_on = 0;
 100 static int ip_rsvp_on;
 101 struct socket *ip_rsvpd;
 102
 103 int     ipforwarding = 0;
 104 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
 105     &ipforwarding, 0, "Enable IP forwarding between interfaces");
 106
 107 static int      ipsendredirects = 1; /* XXX */
 108 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
 109     &ipsendredirects, 0, "Enable sending IP redirects");
 110
 111 int     ip_defttl = IPDEFTTL;
 112 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
 113     &ip_defttl, 0, "Maximum TTL on IP packets");
 114
 115 static int      ip_dosourceroute = 0;
 116 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
 117     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
 118
 119 static int      ip_acceptsourceroute = 0;
 120 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
 121     CTLFLAG_RW, &ip_acceptsourceroute, 0,
 122     "Enable accepting source routed IP packets");
 123
 124 static int      ip_keepfaith = 0;
 125 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
 126         &ip_keepfaith,  0,
 127         "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
 128
 129 static int      nipq = 0;       /* total # of reass queues */
 130 static int      maxnipq;
 131 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
 132         &maxnipq, 0,
 133         "Maximum number of IPv4 fragment reassembly queue entries");
 134
 135 static int    maxfragsperpacket;
 136 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
 137         &maxfragsperpacket, 0,
 138         "Maximum number of IPv4 fragments allowed per packet");
 139
 140 static int      ip_sendsourcequench = 0;
 141 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
 142         &ip_sendsourcequench, 0,
 143         "Enable the transmission of source quench packets");
 144
 145 /*
 146  * XXX - Setting ip_checkinterface mostly implements the receive side of
 147  * the Strong ES model described in RFC 1122, but since the routing table
 148  * and transmit implementation do not implement the Strong ES model,
 149  * setting this to 1 results in an odd hybrid.
 150  *
 151  * XXX - ip_checkinterface currently must be disabled if you use ipnat
 152  * to translate the destination address to another local interface.
 153  *
 154  * XXX - ip_checkinterface must be disabled if you add IP aliases
 155  * to the loopback interface instead of the interface where the
 156  * packets for those addresses are received.
 157  */
 158 static int      ip_checkinterface = 0;
 159 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
 160     &ip_checkinterface, 0, "Verify packet arrives on correct interface");
 161
 162 #ifdef DIAGNOSTIC
 163 static int      ipprintfs = 0;
 164 #endif
 165
 166 static struct ifqueue ipintrq;
 167 static int      ipqmaxlen = IFQ_MAXLEN;
 168
 169 extern  struct domain inetdomain;
 170 extern  struct ipprotosw inetsw[];
 171 u_char  ip_protox[IPPROTO_MAX];
 172 struct  in_ifaddrhead in_ifaddrhead;            /* first inet address */
 173 struct  in_ifaddrhashhead *in_ifaddrhashtbl;    /* inet addr hash table */
 174 u_long  in_ifaddrhmask;                         /* mask for hash table */
 175 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
 176     &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
 177 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
 178     &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
 179
 180 struct ipstat ipstat;
 181 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
 182     &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)");
 183
 184 /* Packet reassembly stuff */
 185 #define IPREASS_NHASH_LOG2      6
 186 #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
 187 #define IPREASS_HMASK           (IPREASS_NHASH - 1)
 188 #define IPREASS_HASH(x,y) \
 189         (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
 190
 191 static struct ipq ipq[IPREASS_NHASH];
 192 const  int    ipintrq_present = 1;
 193
 194 #ifdef IPCTL_DEFMTU
 195 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
 196     &ip_mtu, 0, "Default MTU");
 197 #endif
 198
 199 #ifdef IPSTEALTH
 200 static int      ipstealth = 0;
 201 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
 202     &ipstealth, 0, "");
 203 #endif
 204
 205
 206 /* Firewall hooks */
 207 ip_fw_chk_t *ip_fw_chk_ptr;
 208 int fw_enable = 1 ;
 209 int fw_one_pass = 1;
 210
 211 /* Dummynet hooks */
 212 ip_dn_io_t *ip_dn_io_ptr;
 213
 214 #ifdef PFIL_HOOKS
 215 struct pfil_head inet_pfil_hook;
 216 #endif /* PFIL_HOOKS */
 217
 218 /*
 219  * XXX this is ugly -- the following two global variables are
 220  * used to store packet state while it travels through the stack.
 221  * Note that the code even makes assumptions on the size and
 222  * alignment of fields inside struct ip_srcrt so e.g. adding some
 223  * fields will break the code. This needs to be fixed.
 224  *
 225  * We need to save the IP options in case a protocol wants to respond
 226  * to an incoming packet over the same route if the packet got here
 227  * using IP source routing.  This allows connection establishment and
 228  * maintenance when the remote end is on a network that is not known
 229  * to us.
 230  */
 231 static int      ip_nhops = 0;
 232 static  struct ip_srcrt {
 233         struct  in_addr dst;                    /* final destination */
 234         char    nop;                            /* one NOP to align */
 235         char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
 236         struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
 237 } ip_srcrt;
 238
 239 static void     save_rte(u_char *, struct in_addr);
 240 static int      ip_dooptions(struct mbuf *m, int,
 241                         struct sockaddr_in *next_hop);
 242 static void     ip_forward(struct mbuf *m, int srcrt,
 243                         struct sockaddr_in *next_hop);
 244 static void     ip_freef(struct ipq *);
 245 static struct   mbuf *ip_reass(struct mbuf *, struct ipq *,
 246                 struct ipq *, u_int32_t *, u_int16_t *);
 247
 248 /*
 249  * IP initialization: fill in IP protocol switch table.
 250  * All protocols not implemented in kernel go to raw IP protocol handler.
 251  */
 252 void
 253 ip_init()
 254 {
 255         struct ipprotosw *pr;
 256         int i;
 257
 258         TAILQ_INIT(&in_ifaddrhead);
 259         in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask);
 260         pr = (struct ipprotosw *)pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 261         if (pr == 0)
 262                 panic("ip_init");
 263         for (i = 0; i < IPPROTO_MAX; i++)
 264                 ip_protox[i] = pr - inetsw;
 265         for (pr = (struct ipprotosw *)inetdomain.dom_protosw;
 266             pr < (struct ipprotosw *)inetdomain.dom_protoswNPROTOSW; pr++)
 267                 if (pr->pr_domain->dom_family == PF_INET &&
 268                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
 269                         ip_protox[pr->pr_protocol] = pr - inetsw;
 270
 271 #ifdef PFIL_HOOKS
 272         inet_pfil_hook.ph_type = PFIL_TYPE_AF;
 273         inet_pfil_hook.ph_af = AF_INET;
 274         if ((i = pfil_head_register(&inet_pfil_hook)) != 0)
 275                 printf("%s: WARNING: unable to register pfil hook, "
 276                         "error %d\n", __func__, i);
 277 #endif /* PFIL_HOOKS */
 278
 279         for (i = 0; i < IPREASS_NHASH; i++)
 280             ipq[i].next = ipq[i].prev = &ipq[i];
 281
 282         maxnipq = nmbclusters / 32;
 283         maxfragsperpacket = 16;
 284
 285 #ifndef RANDOM_IP_ID
 286         ip_id = time_second & 0xffff;
 287 #endif
 288         ipintrq.ifq_maxlen = ipqmaxlen;
 289
 290         netisr_register(NETISR_IP, ip_mport, ip_input);
 291 }
 292
 293 /*
 294  * XXX watch out this one. It is perhaps used as a cache for
 295  * the most recently used route ? it is cleared in in_addroute()
 296  * when a new route is successfully created.
 297  */
 298 struct  route ipforward_rt;
 299 static struct   sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
 300
 301 /*
 302  * Ip input routine.  Checksum and byte swap header.  If fragmented
 303  * try to reassemble.  Process options.  Pass to next level.
 304  */
 305 void
 306 ip_input(struct netmsg *msg)
 307 {
 308         struct mbuf *m = ((struct netmsg_packet *)msg)->nm_packet;
 309         struct ip *ip;
 310         struct ipq *fp;
 311         struct in_ifaddr *ia = NULL;
 312         struct ifaddr *ifa;
 313         int    i, hlen, checkif;
 314         u_short sum;
 315         struct in_addr pkt_dst;
 316         u_int32_t divert_info = 0;              /* packet divert/tee info */
 317         struct ip_fw_args args;
 318         int srcrt = 0;                          /* forward (by PFIL_HOOKS) */
 319 #ifdef PFIL_HOOKS
 320         struct in_addr odst;                    /* original dst address(NAT) */
 321 #endif
 322 #ifdef FAST_IPSEC
 323         struct m_tag *mtag;
 324         struct tdb_ident *tdbi;
 325         struct secpolicy *sp;
 326         int s, error;
 327 #endif /* FAST_IPSEC */
 328
 329         args.eh = NULL;
 330         args.oif = NULL;
 331         args.rule = NULL;
 332         args.divert_rule = 0;                   /* divert cookie */
 333         args.next_hop = NULL;
 334
 335         /* Grab info from MT_TAG mbufs prepended to the chain.  */
 336         for (; m && m->m_type == MT_TAG; m = m->m_next) {
 337                 switch(m->_m_tag_id) {
 338                 default:
 339                         printf("ip_input: unrecognised MT_TAG tag %d\n",
 340                             m->_m_tag_id);
 341                         break;
 342
 343                 case PACKET_TAG_DUMMYNET:
 344                         args.rule = ((struct dn_pkt *)m)->rule;
 345                         break;
 346
 347                 case PACKET_TAG_DIVERT:
 348                         args.divert_rule = (int)m->m_hdr.mh_data & 0xffff;
 349                         break;
 350
 351                 case PACKET_TAG_IPFORWARD:
 352                         args.next_hop = (struct sockaddr_in *)m->m_hdr.mh_data;
 353                         break;
 354                 }
 355         }
 356
 357         KASSERT(m != NULL && (m->m_flags & M_PKTHDR) != 0,
 358             ("ip_input: no HDR"));
 359
 360         if (args.rule) {        /* dummynet already filtered us */
 361                 ip = mtod(m, struct ip *);
 362                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 363                 goto iphack ;
 364         }
 365
 366         ipstat.ips_total++;
 367
 368         if (m->m_pkthdr.len < sizeof(struct ip))
 369                 goto tooshort;
 370
 371         if (m->m_len < sizeof (struct ip) &&
 372             (m = m_pullup(m, sizeof (struct ip))) == 0) {
 373                 ipstat.ips_toosmall++;
 374                 return;
 375         }
 376         ip = mtod(m, struct ip *);
 377
 378         if (IP_VHL_V(ip->ip_vhl) != IPVERSION) {
 379                 ipstat.ips_badvers++;
 380                 goto bad;
 381         }
 382
 383         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 384         if (hlen < sizeof(struct ip)) { /* minimum header length */
 385                 ipstat.ips_badhlen++;
 386                 goto bad;
 387         }
 388         if (hlen > m->m_len) {
 389                 if ((m = m_pullup(m, hlen)) == 0) {
 390                         ipstat.ips_badhlen++;
 391                         return;
 392                 }
 393                 ip = mtod(m, struct ip *);
 394         }
 395
 396         /* 127/8 must not appear on wire - RFC1122 */
 397         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
 398             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
 399                 if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
 400                         ipstat.ips_badaddr++;
 401                         goto bad;
 402                 }
 403         }
 404
 405         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
 406                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
 407         } else {
 408                 if (hlen == sizeof(struct ip)) {
 409                         sum = in_cksum_hdr(ip);
 410                 } else {
 411                         sum = in_cksum(m, hlen);
 412                 }
 413         }
 414         if (sum) {
 415                 ipstat.ips_badsum++;
 416                 goto bad;
 417         }
 418
 419         /*
 420          * Convert fields to host representation.
 421          */
 422         ip->ip_len = ntohs(ip->ip_len);
 423         if (ip->ip_len < hlen) {
 424                 ipstat.ips_badlen++;
 425                 goto bad;
 426         }
 427         ip->ip_off = ntohs(ip->ip_off);
 428
 429         /*
 430          * Check that the amount of data in the buffers
 431          * is as at least much as the IP header would have us expect.
 432          * Trim mbufs if longer than we expect.
 433          * Drop packet if shorter than we expect.
 434          */
 435         if (m->m_pkthdr.len < ip->ip_len) {
 436 tooshort:
 437                 ipstat.ips_tooshort++;
 438                 goto bad;
 439         }
 440         if (m->m_pkthdr.len > ip->ip_len) {
 441                 if (m->m_len == m->m_pkthdr.len) {
 442                         m->m_len = ip->ip_len;
 443                         m->m_pkthdr.len = ip->ip_len;
 444                 } else
 445                         m_adj(m, ip->ip_len - m->m_pkthdr.len);
 446         }
 447 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
 448         /*
 449          * Bypass packet filtering for packets from a tunnel (gif).
 450          */
 451         if (ipsec_gethist(m, NULL))
 452                 goto pass;
 453 #endif
 454
 455         /*
 456          * IpHack's section.
 457          * Right now when no processing on packet has done
 458          * and it is still fresh out of network we do our black
 459          * deals with it.
 460          * - Firewall: deny/allow/divert
 461          * - Xlate: translate packet's addr/port (NAT).
 462          * - Pipe: pass pkt through dummynet.
 463          * - Wrap: fake packet's addr/port <unimpl.>
 464          * - Encapsulate: put it in another IP and send out. <unimp.>
 465          */
 466
 467 iphack:
 468 #ifdef PFIL_HOOKS
 469         /*
 470          * Run through list of hooks for input packets.
 471          *
 472          * NB: Beware of the destination address changing (e.g.
 473          *     by NAT rewriting). When this happens, tell
 474          *     ip_forward to do the right thing.
 475          */
 476         odst = ip->ip_dst;
 477         if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
 478             PFIL_IN) != 0)
 479                 return;
 480         if (m == NULL)                  /* consumed by filter */
 481                 return;
 482         ip = mtod(m, struct ip *);
 483         srcrt = (odst.s_addr != ip->ip_dst.s_addr);
 484 #endif /* PFIL_HOOKS */
 485         if (fw_enable && IPFW_LOADED) {
 486                 /*
 487                  * If we've been forwarded from the output side, then
 488                  * skip the firewall a second time
 489                  */
 490                 if (args.next_hop)
 491                         goto ours;
 492
 493                 args.m = m;
 494                 i = ip_fw_chk_ptr(&args);
 495                 m = args.m;
 496
 497                 if ( (i & IP_FW_PORT_DENY_FLAG) || m == NULL) { /* drop */
 498                         if (m)
 499                                 m_freem(m);
 500                         return;
 501                 }
 502                 ip = mtod(m, struct ip *); /* just in case m changed */
 503                 if (i == 0 && args.next_hop == NULL)    /* common case */
 504                         goto pass;
 505                 if (DUMMYNET_LOADED && (i & IP_FW_PORT_DYNT_FLAG) != 0) {
 506                         /* Send packet to the appropriate pipe */
 507                         ip_dn_io_ptr(m, i&0xffff, DN_TO_IP_IN, &args);
 508                         return;
 509                 }
 510 #ifdef IPDIVERT
 511                 if (i != 0 && (i & IP_FW_PORT_DYNT_FLAG) == 0) {
 512                         /* Divert or tee packet */
 513                         divert_info = i;
 514                         goto ours;
 515                 }
 516 #endif
 517                 if (i == 0 && args.next_hop != NULL)
 518                         goto pass;
 519                 /*
 520                  * if we get here, the packet must be dropped
 521                  */
 522                 m_freem(m);
 523                 return;
 524         }
 525 pass:
 526
 527         /*
 528          * Process options and, if not destined for us,
 529          * ship it on.  ip_dooptions returns 1 when an
 530          * error was detected (causing an icmp message
 531          * to be sent and the original packet to be freed).
 532          */
 533         ip_nhops = 0;           /* for source routed packets */
 534         if (hlen > sizeof (struct ip) && ip_dooptions(m, 0, args.next_hop))
 535                 return;
 536
 537         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
 538          * matter if it is destined to another node, or whether it is
 539          * a multicast one, RSVP wants it! and prevents it from being forwarded
 540          * anywhere else. Also checks if the rsvp daemon is running before
 541          * grabbing the packet.
 542          */
 543         if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
 544                 goto ours;
 545
 546         /*
 547          * Check our list of addresses, to see if the packet is for us.
 548          * If we don't have any addresses, assume any unicast packet
 549          * we receive might be for us (and let the upper layers deal
 550          * with it).
 551          */
 552         if (TAILQ_EMPTY(&in_ifaddrhead) &&
 553             (m->m_flags & (M_MCAST|M_BCAST)) == 0)
 554                 goto ours;
 555
 556         /*
 557          * Cache the destination address of the packet; this may be
 558          * changed by use of 'ipfw fwd'.
 559          */
 560         pkt_dst = args.next_hop ? args.next_hop->sin_addr : ip->ip_dst;
 561
 562         /*
 563          * Enable a consistency check between the destination address
 564          * and the arrival interface for a unicast packet (the RFC 1122
 565          * strong ES model) if IP forwarding is disabled and the packet
 566          * is not locally generated and the packet is not subject to
 567          * 'ipfw fwd'.
 568          *
 569          * XXX - Checking also should be disabled if the destination
 570          * address is ipnat'ed to a different interface.
 571          *
 572          * XXX - Checking is incompatible with IP aliases added
 573          * to the loopback interface instead of the interface where
 574          * the packets are received.
 575          */
 576         checkif = ip_checkinterface && (ipforwarding == 0) &&
 577             m->m_pkthdr.rcvif != NULL &&
 578             ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) &&
 579             (args.next_hop == NULL);
 580
 581         /*
 582          * Check for exact addresses in the hash bucket.
 583          */
 584         LIST_FOREACH(ia, INADDR_HASH(pkt_dst.s_addr), ia_hash) {
 585                 /*
 586                  * If the address matches, verify that the packet
 587                  * arrived via the correct interface if checking is
 588                  * enabled.
 589                  */
 590                 if (IA_SIN(ia)->sin_addr.s_addr == pkt_dst.s_addr &&
 591                     (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
 592                         goto ours;
 593         }
 594         /*
 595          * Check for broadcast addresses.
 596          *
 597          * Only accept broadcast packets that arrive via the matching
 598          * interface.  Reception of forwarded directed broadcasts would
 599          * be handled via ip_forward() and ether_output() with the loopback
 600          * into the stack for SIMPLEX interfaces handled by ether_output().
 601          */
 602         if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
 603                 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
 604                         if (ifa->ifa_addr->sa_family != AF_INET)
 605                                 continue;
 606                         ia = ifatoia(ifa);
 607                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 608                             pkt_dst.s_addr)
 609                                 goto ours;
 610                         if (ia->ia_netbroadcast.s_addr == pkt_dst.s_addr)
 611                                 goto ours;
 612 #ifdef BOOTP_COMPAT
 613                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
 614                                 goto ours;
 615 #endif
 616                 }
 617         }
 618         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
 619                 struct in_multi *inm;
 620                 if (ip_mrouter) {
 621                         /*
 622                          * If we are acting as a multicast router, all
 623                          * incoming multicast packets are passed to the
 624                          * kernel-level multicast forwarding function.
 625                          * The packet is returned (relatively) intact; if
 626                          * ip_mforward() returns a non-zero value, the packet
 627                          * must be discarded, else it may be accepted below.
 628                          */
 629                         if (ip_mforward &&
 630                             ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
 631                                 ipstat.ips_cantforward++;
 632                                 m_freem(m);
 633                                 return;
 634                         }
 635
 636                         /*
 637                          * The process-level routing daemon needs to receive
 638                          * all multicast IGMP packets, whether or not this
 639                          * host belongs to their destination groups.
 640                          */
 641                         if (ip->ip_p == IPPROTO_IGMP)
 642                                 goto ours;
 643                         ipstat.ips_forward++;
 644                 }
 645                 /*
 646                  * See if we belong to the destination multicast group on the
 647                  * arrival interface.
 648                  */
 649                 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
 650                 if (inm == NULL) {
 651                         ipstat.ips_notmember++;
 652                         m_freem(m);
 653                         return;
 654                 }
 655                 goto ours;
 656         }
 657         if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
 658                 goto ours;
 659         if (ip->ip_dst.s_addr == INADDR_ANY)
 660                 goto ours;
 661
 662         /*
 663          * FAITH(Firewall Aided Internet Translator)
 664          */
 665         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 666                 if (ip_keepfaith) {
 667                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
 668                                 goto ours;
 669                 }
 670                 m_freem(m);
 671                 return;
 672         }
 673
 674         /*
 675          * Not for us; forward if possible and desirable.
 676          */
 677         if (ipforwarding == 0) {
 678                 ipstat.ips_cantforward++;
 679                 m_freem(m);
 680         } else {
 681 #ifdef IPSEC
 682                 /*
 683                  * Enforce inbound IPsec SPD.
 684                  */
 685                 if (ipsec4_in_reject(m, NULL)) {
 686                         ipsecstat.in_polvio++;
 687                         goto bad;
 688                 }
 689 #endif /* IPSEC */
 690 #ifdef FAST_IPSEC
 691                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 692                 s = splnet();
 693                 if (mtag != NULL) {
 694                         tdbi = (struct tdb_ident *)(mtag + 1);
 695                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 696                 } else {
 697                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 698                                                    IP_FORWARDING, &error);
 699                 }
 700                 if (sp == NULL) {       /* NB: can happen if error */
 701                         splx(s);
 702                         /*XXX error stat???*/
 703                         DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 704                         goto bad;
 705                 }
 706
 707                 /*
 708                  * Check security policy against packet attributes.
 709                  */
 710                 error = ipsec_in_reject(sp, m);
 711                 KEY_FREESP(&sp);
 712                 splx(s);
 713                 if (error) {
 714                         ipstat.ips_cantforward++;
 715                         goto bad;
 716                 }
 717 #endif /* FAST_IPSEC */
 718                 ip_forward(m, srcrt, args.next_hop);
 719         }
 720         return;
 721
 722 ours:
 723 #ifdef IPSTEALTH
 724         /*
 725          * IPSTEALTH: Process non-routing options only
 726          * if the packet is destined for us.
 727          */
 728         if (ipstealth && hlen > sizeof (struct ip) &&
 729             ip_dooptions(m, 1, args.next_hop))
 730                 return;
 731 #endif /* IPSTEALTH */
 732
 733         /* Count the packet in the ip address stats */
 734         if (ia != NULL) {
 735                 ia->ia_ifa.if_ipackets++;
 736                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
 737         }
 738
 739         /*
 740          * If offset or IP_MF are set, must reassemble.
 741          * Otherwise, nothing need be done.
 742          * (We could look in the reassembly queue to see
 743          * if the packet was previously fragmented,
 744          * but it's not worth the time; just let them time out.)
 745          */
 746         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 747
 748                 /* If maxnipq is 0, never accept fragments. */
 749                 if (maxnipq == 0) {
 750                         ipstat.ips_fragments++;
 751                         ipstat.ips_fragdropped++;
 752                         goto bad;
 753                 }
 754
 755                 sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
 756                 /*
 757                  * Look for queue of fragments
 758                  * of this datagram.
 759                  */
 760                 for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next)
 761                         if (ip->ip_id == fp->ipq_id &&
 762                             ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 763                             ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 764                             ip->ip_p == fp->ipq_p)
 765                                 goto found;
 766
 767                 fp = 0;
 768
 769                 /*
 770                  * Enforce upper bound on number of fragmented packets
 771                  * for which we attempt reassembly;
 772                  * If maxnipq is -1, accept all fragments without limitation.
 773                  */
 774                 if ((nipq > maxnipq) && (maxnipq > 0)) {
 775                     /*
 776                      * drop something from the tail of the current queue
 777                      * before proceeding further
 778                      */
 779                     if (ipq[sum].prev == &ipq[sum]) {   /* gak */
 780                         for (i = 0; i < IPREASS_NHASH; i++) {
 781                             if (ipq[i].prev != &ipq[i]) {
 782                                 ipstat.ips_fragtimeout +=
 783                                     ipq[i].prev->ipq_nfrags;
 784                                 ip_freef(ipq[i].prev);
 785                                 break;
 786                             }
 787                         }
 788                     } else {
 789                         ipstat.ips_fragtimeout += ipq[sum].prev->ipq_nfrags;
 790                         ip_freef(ipq[sum].prev);
 791                     }
 792                 }
 793 found:
 794                 /*
 795                  * Adjust ip_len to not reflect header,
 796                  * convert offset of this to bytes.
 797                  */
 798                 ip->ip_len -= hlen;
 799                 if (ip->ip_off & IP_MF) {
 800                         /*
 801                          * Make sure that fragments have a data length
 802                          * that's a non-zero multiple of 8 bytes.
 803                          */
 804                         if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
 805                                 ipstat.ips_toosmall++; /* XXX */
 806                                 goto bad;
 807                         }
 808                         m->m_flags |= M_FRAG;
 809                 } else
 810                         m->m_flags &= ~M_FRAG;
 811                 ip->ip_off <<= 3;
 812
 813                 /*
 814                  * Attempt reassembly; if it succeeds, proceed.
 815                  * ip_reass() will return a different mbuf, and update
 816                  * the divert info in divert_info and args.divert_rule.
 817                  */
 818                 ipstat.ips_fragments++;
 819                 m->m_pkthdr.header = ip;
 820                 m = ip_reass(m,
 821                     fp, &ipq[sum], &divert_info, &args.divert_rule);
 822                 if (m == 0)
 823                         return;
 824                 ipstat.ips_reassembled++;
 825                 ip = mtod(m, struct ip *);
 826                 /* Get the header length of the reassembled packet */
 827                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 828 #ifdef IPDIVERT
 829                 /* Restore original checksum before diverting packet */
 830                 if (divert_info != 0) {
 831                         ip->ip_len += hlen;
 832                         ip->ip_len = htons(ip->ip_len);
 833                         ip->ip_off = htons(ip->ip_off);
 834                         ip->ip_sum = 0;
 835                         if (hlen == sizeof(struct ip))
 836                                 ip->ip_sum = in_cksum_hdr(ip);
 837                         else
 838                                 ip->ip_sum = in_cksum(m, hlen);
 839                         ip->ip_off = ntohs(ip->ip_off);
 840                         ip->ip_len = ntohs(ip->ip_len);
 841                         ip->ip_len -= hlen;
 842                 }
 843 #endif
 844         } else {
 845                 ip->ip_len -= hlen;
 846         }
 847
 848 #ifdef IPDIVERT
 849         /*
 850          * Divert or tee packet to the divert protocol if required.
 851          */
 852         if (divert_info != 0) {
 853                 struct mbuf *clone = NULL;
 854
 855                 /* Clone packet if we're doing a 'tee' */
 856                 if ((divert_info & IP_FW_PORT_TEE_FLAG) != 0)
 857                         clone = m_dup(m, M_DONTWAIT);
 858
 859                 /* Restore packet header fields to original values */
 860                 ip->ip_len += hlen;
 861                 ip->ip_len = htons(ip->ip_len);
 862                 ip->ip_off = htons(ip->ip_off);
 863
 864                 /* Deliver packet to divert input routine */
 865                 divert_packet(m, 1, divert_info & 0xffff, args.divert_rule);
 866                 ipstat.ips_delivered++;
 867
 868                 /* If 'tee', continue with original packet */
 869                 if (clone == NULL)
 870                         return;
 871                 m = clone;
 872                 ip = mtod(m, struct ip *);
 873                 ip->ip_len += hlen;
 874                 /*
 875                  * Jump backwards to complete processing of the
 876                  * packet. But first clear divert_info to avoid
 877                  * entering this block again.
 878                  * We do not need to clear args.divert_rule
 879                  * or args.next_hop as they will not be used.
 880                  */
 881                 divert_info = 0;
 882                 goto pass;
 883         }
 884 #endif
 885
 886 #ifdef IPSEC
 887         /*
 888          * enforce IPsec policy checking if we are seeing last header.
 889          * note that we do not visit this with protocols with pcb layer
 890          * code - like udp/tcp/raw ip.
 891          */
 892         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
 893             ipsec4_in_reject(m, NULL)) {
 894                 ipsecstat.in_polvio++;
 895                 goto bad;
 896         }
 897 #endif
 898 #if FAST_IPSEC
 899         /*
 900          * enforce IPsec policy checking if we are seeing last header.
 901          * note that we do not visit this with protocols with pcb layer
 902          * code - like udp/tcp/raw ip.
 903          */
 904         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 905                 /*
 906                  * Check if the packet has already had IPsec processing
 907                  * done.  If so, then just pass it along.  This tag gets
 908                  * set during AH, ESP, etc. input handling, before the
 909                  * packet is returned to the ip input queue for delivery.
 910                  */
 911                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 912                 s = splnet();
 913                 if (mtag != NULL) {
 914                         tdbi = (struct tdb_ident *)(mtag + 1);
 915                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 916                 } else {
 917                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 918                                                    IP_FORWARDING, &error);
 919                 }
 920                 if (sp != NULL) {
 921                         /*
 922                          * Check security policy against packet attributes.
 923                          */
 924                         error = ipsec_in_reject(sp, m);
 925                         KEY_FREESP(&sp);
 926                 } else {
 927                         /* XXX error stat??? */
 928                         error = EINVAL;
 929 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 930                         goto bad;
 931                 }
 932                 splx(s);
 933                 if (error)
 934                         goto bad;
 935         }
 936 #endif /* FAST_IPSEC */
 937
 938         /*
 939          * Switch out to protocol's input routine.
 940          *
 941          * XXX queue packet to protocol's message port.
 942          */
 943         ipstat.ips_delivered++;
 944         if (args.next_hop && ip->ip_p == IPPROTO_TCP) {
 945                 /* TCP needs IPFORWARD info if available */
 946                 struct m_hdr tag;
 947
 948                 tag.mh_type = MT_TAG;
 949                 tag.mh_flags = PACKET_TAG_IPFORWARD;
 950                 tag.mh_data = (caddr_t)args.next_hop;
 951                 tag.mh_next = m;
 952
 953                 (*inetsw[ip_protox[ip->ip_p]].pr_input)(
 954                         (struct mbuf *)&tag, hlen, ip->ip_p);
 955         } else {
 956                 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen, ip->ip_p);
 957         }
 958         return;
 959 bad:
 960         m_freem(m);
 961 }
 962
 963 /*
 964  * Take incoming datagram fragment and try to reassemble it into
 965  * whole datagram.  If a chain for reassembly of this datagram already
 966  * exists, then it is given as fp; otherwise have to make a chain.
 967  *
 968  * When IPDIVERT enabled, keep additional state with each packet that
 969  * tells us if we need to divert or tee the packet we're building.
 970  * In particular, *divinfo includes the port and TEE flag,
 971  * *divert_rule is the number of the matching rule.
 972  */
 973
 974 static struct mbuf *
 975 ip_reass(struct mbuf *m, struct ipq *fp, struct ipq *where,
 976         u_int32_t *divinfo, u_int16_t *divert_rule)
 977 {
 978         struct ip *ip = mtod(m, struct ip *);
 979         struct mbuf *p = 0, *q, *nq;
 980         struct mbuf *t;
 981         int hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 982         int i, next;
 983
 984         /*
 985          * Presence of header sizes in mbufs
 986          * would confuse code below.
 987          */
 988         m->m_data += hlen;
 989         m->m_len -= hlen;
 990
 991         /*
 992          * If first fragment to arrive, create a reassembly queue.
 993          */
 994         if (fp == 0) {
 995                 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
 996                         goto dropfrag;
 997                 fp = mtod(t, struct ipq *);
 998                 insque(fp, where);
 999                 nipq++;
1000                 fp->ipq_nfrags = 1;
1001                 fp->ipq_ttl = IPFRAGTTL;
1002                 fp->ipq_p = ip->ip_p;
1003                 fp->ipq_id = ip->ip_id;
1004                 fp->ipq_src = ip->ip_src;
1005                 fp->ipq_dst = ip->ip_dst;
1006                 fp->ipq_frags = m;
1007                 m->m_nextpkt = NULL;
1008 #ifdef IPDIVERT
1009                 fp->ipq_div_info = 0;
1010                 fp->ipq_div_cookie = 0;
1011 #endif
1012                 goto inserted;
1013         } else {
1014                 fp->ipq_nfrags++;
1015         }
1016
1017 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.header))
1018
1019         /*
1020          * Find a segment which begins after this one does.
1021          */
1022         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
1023                 if (GETIP(q)->ip_off > ip->ip_off)
1024                         break;
1025
1026         /*
1027          * If there is a preceding segment, it may provide some of
1028          * our data already.  If so, drop the data from the incoming
1029          * segment.  If it provides all of our data, drop us, otherwise
1030          * stick new segment in the proper place.
1031          *
1032          * If some of the data is dropped from the the preceding
1033          * segment, then it's checksum is invalidated.
1034          */
1035         if (p) {
1036                 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
1037                 if (i > 0) {
1038                         if (i >= ip->ip_len)
1039                                 goto dropfrag;
1040                         m_adj(m, i);
1041                         m->m_pkthdr.csum_flags = 0;
1042                         ip->ip_off += i;
1043                         ip->ip_len -= i;
1044                 }
1045                 m->m_nextpkt = p->m_nextpkt;
1046                 p->m_nextpkt = m;
1047         } else {
1048                 m->m_nextpkt = fp->ipq_frags;
1049                 fp->ipq_frags = m;
1050         }
1051
1052         /*
1053          * While we overlap succeeding segments trim them or,
1054          * if they are completely covered, dequeue them.
1055          */
1056         for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
1057              q = nq) {
1058                 i = (ip->ip_off + ip->ip_len) -
1059                     GETIP(q)->ip_off;
1060                 if (i < GETIP(q)->ip_len) {
1061                         GETIP(q)->ip_len -= i;
1062                         GETIP(q)->ip_off += i;
1063                         m_adj(q, i);
1064                         q->m_pkthdr.csum_flags = 0;
1065                         break;
1066                 }
1067                 nq = q->m_nextpkt;
1068                 m->m_nextpkt = nq;
1069                 ipstat.ips_fragdropped++;
1070                 fp->ipq_nfrags--;
1071                 m_freem(q);
1072         }
1073
1074 inserted:
1075
1076 #ifdef IPDIVERT
1077         /*
1078          * Transfer firewall instructions to the fragment structure.
1079          * Only trust info in the fragment at offset 0.
1080          */
1081         if (ip->ip_off == 0) {
1082                 fp->ipq_div_info = *divinfo;
1083                 fp->ipq_div_cookie = *divert_rule;
1084         }
1085         *divinfo = 0;
1086         *divert_rule = 0;
1087 #endif
1088
1089         /*
1090          * Check for complete reassembly and perform frag per packet
1091          * limiting.
1092          *
1093          * Frag limiting is performed here so that the nth frag has
1094          * a chance to complete the packet before we drop the packet.
1095          * As a result, n+1 frags are actually allowed per packet, but
1096          * only n will ever be stored. (n = maxfragsperpacket.)
1097          *
1098          */
1099         next = 0;
1100         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
1101                 if (GETIP(q)->ip_off != next) {
1102                         if (fp->ipq_nfrags > maxfragsperpacket) {
1103                                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1104                                 ip_freef(fp);
1105                         }
1106                         return (0);
1107                 }
1108                 next += GETIP(q)->ip_len;
1109         }
1110         /* Make sure the last packet didn't have the IP_MF flag */
1111         if (p->m_flags & M_FRAG) {
1112                 if (fp->ipq_nfrags > maxfragsperpacket) {
1113                         ipstat.ips_fragdropped += fp->ipq_nfrags;
1114                         ip_freef(fp);
1115                 }
1116                 return (0);
1117         }
1118
1119         /*
1120          * Reassembly is complete.  Make sure the packet is a sane size.
1121          */
1122         q = fp->ipq_frags;
1123         ip = GETIP(q);
1124         if (next + (IP_VHL_HL(ip->ip_vhl) << 2) > IP_MAXPACKET) {
1125                 ipstat.ips_toolong++;
1126                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1127                 ip_freef(fp);
1128                 return (0);
1129         }
1130
1131         /*
1132          * Concatenate fragments.
1133          */
1134         m = q;
1135         t = m->m_next;
1136         m->m_next = 0;
1137         m_cat(m, t);
1138         nq = q->m_nextpkt;
1139         q->m_nextpkt = 0;
1140         for (q = nq; q != NULL; q = nq) {
1141                 nq = q->m_nextpkt;
1142                 q->m_nextpkt = NULL;
1143                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
1144                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
1145                 m_cat(m, q);
1146         }
1147
1148 #ifdef IPDIVERT
1149         /*
1150          * Extract firewall instructions from the fragment structure.
1151          */
1152         *divinfo = fp->ipq_div_info;
1153         *divert_rule = fp->ipq_div_cookie;
1154 #endif
1155
1156         /*
1157          * Create header for new ip packet by
1158          * modifying header of first packet;
1159          * dequeue and discard fragment reassembly header.
1160          * Make header visible.
1161          */
1162         ip->ip_len = next;
1163         ip->ip_src = fp->ipq_src;
1164         ip->ip_dst = fp->ipq_dst;
1165         remque(fp);
1166         nipq--;
1167         (void) m_free(dtom(fp));
1168         m->m_len += (IP_VHL_HL(ip->ip_vhl) << 2);
1169         m->m_data -= (IP_VHL_HL(ip->ip_vhl) << 2);
1170         /* some debugging cruft by sklower, below, will go away soon */
1171         if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
1172                 int plen = 0;
1173                 for (t = m; t; t = t->m_next)
1174                         plen += t->m_len;
1175                 m->m_pkthdr.len = plen;
1176         }
1177         return (m);
1178
1179 dropfrag:
1180 #ifdef IPDIVERT
1181         *divinfo = 0;
1182         *divert_rule = 0;
1183 #endif
1184         ipstat.ips_fragdropped++;
1185         if (fp != 0)
1186                 fp->ipq_nfrags--;
1187         m_freem(m);
1188         return (0);
1189
1190 #undef GETIP
1191 }
1192
1193 /*
1194  * Free a fragment reassembly header and all
1195  * associated datagrams.
1196  */
1197 static void
1198 ip_freef(fp)
1199         struct ipq *fp;
1200 {
1201         struct mbuf *q;
1202
1203         while (fp->ipq_frags) {
1204                 q = fp->ipq_frags;
1205                 fp->ipq_frags = q->m_nextpkt;
1206                 m_freem(q);
1207         }
1208         remque(fp);
1209         (void) m_free(dtom(fp));
1210         nipq--;
1211 }
1212
1213 /*
1214  * IP timer processing;
1215  * if a timer expires on a reassembly
1216  * queue, discard it.
1217  */
1218 void
1219 ip_slowtimo()
1220 {
1221         struct ipq *fp;
1222         int s = splnet();
1223         int i;
1224
1225         for (i = 0; i < IPREASS_NHASH; i++) {
1226                 fp = ipq[i].next;
1227                 if (fp == 0)
1228                         continue;
1229                 while (fp != &ipq[i]) {
1230                         --fp->ipq_ttl;
1231                         fp = fp->next;
1232                         if (fp->prev->ipq_ttl == 0) {
1233                                 ipstat.ips_fragtimeout += fp->prev->ipq_nfrags;
1234                                 ip_freef(fp->prev);
1235                         }
1236                 }
1237         }
1238         /*
1239          * If we are over the maximum number of fragments
1240          * (due to the limit being lowered), drain off
1241          * enough to get down to the new limit.
1242          */
1243         if (maxnipq >= 0 && nipq > maxnipq) {
1244                 for (i = 0; i < IPREASS_NHASH; i++) {
1245                         while (nipq > maxnipq &&
1246                                 (ipq[i].next != &ipq[i])) {
1247                                 ipstat.ips_fragdropped +=
1248                                     ipq[i].next->ipq_nfrags;
1249                                 ip_freef(ipq[i].next);
1250                         }
1251                 }
1252         }
1253         ipflow_slowtimo();
1254         splx(s);
1255 }
1256
1257 /*
1258  * Drain off all datagram fragments.
1259  */
1260 void
1261 ip_drain()
1262 {
1263         int     i;
1264
1265         for (i = 0; i < IPREASS_NHASH; i++) {
1266                 while (ipq[i].next != &ipq[i]) {
1267                         ipstat.ips_fragdropped += ipq[i].next->ipq_nfrags;
1268                         ip_freef(ipq[i].next);
1269                 }
1270         }
1271         in_rtqdrain();
1272 }
1273
1274 /*
1275  * Do option processing on a datagram,
1276  * possibly discarding it if bad options are encountered,
1277  * or forwarding it if source-routed.
1278  * The pass argument is used when operating in the IPSTEALTH
1279  * mode to tell what options to process:
1280  * [LS]SRR (pass 0) or the others (pass 1).
1281  * The reason for as many as two passes is that when doing IPSTEALTH,
1282  * non-routing options should be processed only if the packet is for us.
1283  * Returns 1 if packet has been forwarded/freed,
1284  * 0 if the packet should be processed further.
1285  */
1286 static int
1287 ip_dooptions(struct mbuf *m, int pass, struct sockaddr_in *next_hop)
1288 {
1289         struct ip *ip = mtod(m, struct ip *);
1290         u_char *cp;
1291         struct in_ifaddr *ia;
1292         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1293         struct in_addr *sin, dst;
1294         n_time ntime;
1295
1296         dst = ip->ip_dst;
1297         cp = (u_char *)(ip + 1);
1298         cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
1299         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1300                 opt = cp[IPOPT_OPTVAL];
1301                 if (opt == IPOPT_EOL)
1302                         break;
1303                 if (opt == IPOPT_NOP)
1304                         optlen = 1;
1305                 else {
1306                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
1307                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1308                                 goto bad;
1309                         }
1310                         optlen = cp[IPOPT_OLEN];
1311                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
1312                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1313                                 goto bad;
1314                         }
1315                 }
1316                 switch (opt) {
1317
1318                 default:
1319                         break;
1320
1321                 /*
1322                  * Source routing with record.
1323                  * Find interface with current destination address.
1324                  * If none on this machine then drop if strictly routed,
1325                  * or do nothing if loosely routed.
1326                  * Record interface address and bring up next address
1327                  * component.  If strictly routed make sure next
1328                  * address is on directly accessible net.
1329                  */
1330                 case IPOPT_LSRR:
1331                 case IPOPT_SSRR:
1332 #ifdef IPSTEALTH
1333                         if (ipstealth && pass > 0)
1334                                 break;
1335 #endif
1336                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1337                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1338                                 goto bad;
1339                         }
1340                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1341                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1342                                 goto bad;
1343                         }
1344                         ipaddr.sin_addr = ip->ip_dst;
1345                         ia = (struct in_ifaddr *)
1346                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
1347                         if (ia == 0) {
1348                                 if (opt == IPOPT_SSRR) {
1349                                         type = ICMP_UNREACH;
1350                                         code = ICMP_UNREACH_SRCFAIL;
1351                                         goto bad;
1352                                 }
1353                                 if (!ip_dosourceroute)
1354                                         goto nosourcerouting;
1355                                 /*
1356                                  * Loose routing, and not at next destination
1357                                  * yet; nothing to do except forward.
1358                                  */
1359                                 break;
1360                         }
1361                         off--;                  /* 0 origin */
1362                         if (off > optlen - (int)sizeof(struct in_addr)) {
1363                                 /*
1364                                  * End of source route.  Should be for us.
1365                                  */
1366                                 if (!ip_acceptsourceroute)
1367                                         goto nosourcerouting;
1368                                 save_rte(cp, ip->ip_src);
1369                                 break;
1370                         }
1371 #ifdef IPSTEALTH
1372                         if (ipstealth)
1373                                 goto dropit;
1374 #endif
1375                         if (!ip_dosourceroute) {
1376                                 if (ipforwarding) {
1377                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
1378                                         /*
1379                                          * Acting as a router, so generate ICMP
1380                                          */
1381 nosourcerouting:
1382                                         strcpy(buf, inet_ntoa(ip->ip_dst));
1383                                         log(LOG_WARNING,
1384                                             "attempted source route from %s to %s\n",
1385                                             inet_ntoa(ip->ip_src), buf);
1386                                         type = ICMP_UNREACH;
1387                                         code = ICMP_UNREACH_SRCFAIL;
1388                                         goto bad;
1389                                 } else {
1390                                         /*
1391                                          * Not acting as a router, so silently drop.
1392                                          */
1393 #ifdef IPSTEALTH
1394 dropit:
1395 #endif
1396                                         ipstat.ips_cantforward++;
1397                                         m_freem(m);
1398                                         return (1);
1399                                 }
1400                         }
1401
1402                         /*
1403                          * locate outgoing interface
1404                          */
1405                         (void)memcpy(&ipaddr.sin_addr, cp + off,
1406                             sizeof(ipaddr.sin_addr));
1407
1408                         if (opt == IPOPT_SSRR) {
1409 #define INA     struct in_ifaddr *
1410 #define SA      struct sockaddr *
1411                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
1412                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1413                         } else
1414                                 ia = ip_rtaddr(ipaddr.sin_addr, &ipforward_rt);
1415                         if (ia == 0) {
1416                                 type = ICMP_UNREACH;
1417                                 code = ICMP_UNREACH_SRCFAIL;
1418                                 goto bad;
1419                         }
1420                         ip->ip_dst = ipaddr.sin_addr;
1421                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1422                             sizeof(struct in_addr));
1423                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1424                         /*
1425                          * Let ip_intr's mcast routing check handle mcast pkts
1426                          */
1427                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
1428                         break;
1429
1430                 case IPOPT_RR:
1431 #ifdef IPSTEALTH
1432                         if (ipstealth && pass == 0)
1433                                 break;
1434 #endif
1435                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1436                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1437                                 goto bad;
1438                         }
1439                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1440                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1441                                 goto bad;
1442                         }
1443                         /*
1444                          * If no space remains, ignore.
1445                          */
1446                         off--;                  /* 0 origin */
1447                         if (off > optlen - (int)sizeof(struct in_addr))
1448                                 break;
1449                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
1450                             sizeof(ipaddr.sin_addr));
1451                         /*
1452                          * locate outgoing interface; if we're the destination,
1453                          * use the incoming interface (should be same).
1454                          */
1455                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
1456                             (ia = ip_rtaddr(ipaddr.sin_addr,
1457                             &ipforward_rt)) == 0) {
1458                                 type = ICMP_UNREACH;
1459                                 code = ICMP_UNREACH_HOST;
1460                                 goto bad;
1461                         }
1462                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1463                             sizeof(struct in_addr));
1464                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1465                         break;
1466
1467                 case IPOPT_TS:
1468 #ifdef IPSTEALTH
1469                         if (ipstealth && pass == 0)
1470                                 break;
1471 #endif
1472                         code = cp - (u_char *)ip;
1473                         if (optlen < 4 || optlen > 40) {
1474                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1475                                 goto bad;
1476                         }
1477                         if ((off = cp[IPOPT_OFFSET]) < 5) {
1478                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1479                                 goto bad;
1480                         }
1481                         if (off > optlen - (int)sizeof(int32_t)) {
1482                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
1483                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
1484                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1485                                         goto bad;
1486                                 }
1487                                 break;
1488                         }
1489                         off--;                          /* 0 origin */
1490                         sin = (struct in_addr *)(cp + off);
1491                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
1492
1493                         case IPOPT_TS_TSONLY:
1494                                 break;
1495
1496                         case IPOPT_TS_TSANDADDR:
1497                                 if (off + sizeof(n_time) +
1498                                     sizeof(struct in_addr) > optlen) {
1499                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1500                                         goto bad;
1501                                 }
1502                                 ipaddr.sin_addr = dst;
1503                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
1504                                                             m->m_pkthdr.rcvif);
1505                                 if (ia == 0)
1506                                         continue;
1507                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
1508                                     sizeof(struct in_addr));
1509                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1510                                 off += sizeof(struct in_addr);
1511                                 break;
1512
1513                         case IPOPT_TS_PRESPEC:
1514                                 if (off + sizeof(n_time) +
1515                                     sizeof(struct in_addr) > optlen) {
1516                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1517                                         goto bad;
1518                                 }
1519                                 (void)memcpy(&ipaddr.sin_addr, sin,
1520                                     sizeof(struct in_addr));
1521                                 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
1522                                         continue;
1523                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1524                                 off += sizeof(struct in_addr);
1525                                 break;
1526
1527                         default:
1528                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
1529                                 goto bad;
1530                         }
1531                         ntime = iptime();
1532                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
1533                         cp[IPOPT_OFFSET] += sizeof(n_time);
1534                 }
1535         }
1536         if (forward && ipforwarding) {
1537                 ip_forward(m, 1, next_hop);
1538                 return (1);
1539         }
1540         return (0);
1541 bad:
1542         icmp_error(m, type, code, 0, 0);
1543         ipstat.ips_badoptions++;
1544         return (1);
1545 }
1546
1547 /*
1548  * Given address of next destination (final or next hop),
1549  * return internet address info of interface to be used to get there.
1550  */
1551 struct in_ifaddr *
1552 ip_rtaddr(dst, rt)
1553         struct in_addr dst;
1554         struct route *rt;
1555 {
1556         struct sockaddr_in *sin;
1557
1558         sin = (struct sockaddr_in *)&rt->ro_dst;
1559
1560         if (rt->ro_rt == 0 ||
1561             dst.s_addr != sin->sin_addr.s_addr) {
1562                 if (rt->ro_rt) {
1563                         RTFREE(rt->ro_rt);
1564                         rt->ro_rt = 0;
1565                 }
1566                 sin->sin_family = AF_INET;
1567                 sin->sin_len = sizeof(*sin);
1568                 sin->sin_addr = dst;
1569
1570                 rtalloc_ign(rt, RTF_PRCLONING);
1571         }
1572         if (rt->ro_rt == 0)
1573                 return ((struct in_ifaddr *)0);
1574         return (ifatoia(rt->ro_rt->rt_ifa));
1575 }
1576
1577 /*
1578  * Save incoming source route for use in replies,
1579  * to be picked up later by ip_srcroute if the receiver is interested.
1580  */
1581 void
1582 save_rte(option, dst)
1583         u_char *option;
1584         struct in_addr dst;
1585 {
1586         unsigned olen;
1587
1588         olen = option[IPOPT_OLEN];
1589 #ifdef DIAGNOSTIC
1590         if (ipprintfs)
1591                 printf("save_rte: olen %d\n", olen);
1592 #endif
1593         if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
1594                 return;
1595         bcopy(option, ip_srcrt.srcopt, olen);
1596         ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1597         ip_srcrt.dst = dst;
1598 }
1599
1600 /*
1601  * Retrieve incoming source route for use in replies,
1602  * in the same form used by setsockopt.
1603  * The first hop is placed before the options, will be removed later.
1604  */
1605 struct mbuf *
1606 ip_srcroute()
1607 {
1608         struct in_addr *p, *q;
1609         struct mbuf *m;
1610
1611         if (ip_nhops == 0)
1612                 return ((struct mbuf *)0);
1613         m = m_get(M_DONTWAIT, MT_HEADER);
1614         if (m == 0)
1615                 return ((struct mbuf *)0);
1616
1617 #define OPTSIZ  (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1618
1619         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1620         m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
1621             OPTSIZ;
1622 #ifdef DIAGNOSTIC
1623         if (ipprintfs)
1624                 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1625 #endif
1626
1627         /*
1628          * First save first hop for return route
1629          */
1630         p = &ip_srcrt.route[ip_nhops - 1];
1631         *(mtod(m, struct in_addr *)) = *p--;
1632 #ifdef DIAGNOSTIC
1633         if (ipprintfs)
1634                 printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr));
1635 #endif
1636
1637         /*
1638          * Copy option fields and padding (nop) to mbuf.
1639          */
1640         ip_srcrt.nop = IPOPT_NOP;
1641         ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1642         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
1643             &ip_srcrt.nop, OPTSIZ);
1644         q = (struct in_addr *)(mtod(m, caddr_t) +
1645             sizeof(struct in_addr) + OPTSIZ);
1646 #undef OPTSIZ
1647         /*
1648          * Record return path as an IP source route,
1649          * reversing the path (pointers are now aligned).
1650          */
1651         while (p >= ip_srcrt.route) {
1652 #ifdef DIAGNOSTIC
1653                 if (ipprintfs)
1654                         printf(" %lx", (u_long)ntohl(q->s_addr));
1655 #endif
1656                 *q++ = *p--;
1657         }
1658         /*
1659          * Last hop goes to final destination.
1660          */
1661         *q = ip_srcrt.dst;
1662 #ifdef DIAGNOSTIC
1663         if (ipprintfs)
1664                 printf(" %lx\n", (u_long)ntohl(q->s_addr));
1665 #endif
1666         return (m);
1667 }
1668
1669 /*
1670  * Strip out IP options.
1671  */
1672 void
1673 ip_stripoptions(struct mbuf *m)
1674 {
1675         int datalen;
1676         struct ip *ip = mtod(m, struct ip *);
1677         caddr_t opts;
1678         int optlen;
1679
1680         optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
1681         opts = (caddr_t)(ip + 1);
1682         datalen = m->m_len - (sizeof(struct ip) + optlen);
1683         bcopy(opts + optlen, opts, datalen);
1684         m->m_len -= optlen;
1685         if (m->m_flags & M_PKTHDR)
1686                 m->m_pkthdr.len -= optlen;
1687         ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2);
1688 }
1689
1690 u_char inetctlerrmap[PRC_NCMDS] = {
1691         0,              0,              0,              0,
1692         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
1693         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
1694         EMSGSIZE,       EHOSTUNREACH,   0,              0,
1695         0,              0,              0,              0,
1696         ENOPROTOOPT,    ECONNREFUSED
1697 };
1698
1699 /*
1700  * Forward a packet.  If some error occurs return the sender
1701  * an icmp packet.  Note we can't always generate a meaningful
1702  * icmp message because icmp doesn't have a large enough repertoire
1703  * of codes and types.
1704  *
1705  * If not forwarding, just drop the packet.  This could be confusing
1706  * if ipforwarding was zero but some routing protocol was advancing
1707  * us as a gateway to somewhere.  However, we must let the routing
1708  * protocol deal with that.
1709  *
1710  * The srcrt parameter indicates whether the packet is being forwarded
1711  * via a source route.
1712  */
1713 static void
1714 ip_forward(struct mbuf *m, int srcrt, struct sockaddr_in *next_hop)
1715 {
1716         struct ip *ip = mtod(m, struct ip *);
1717         struct sockaddr_in *sin;
1718         struct rtentry *rt;
1719         int error, type = 0, code = 0;
1720         struct mbuf *mcopy;
1721         n_long dest;
1722         struct in_addr pkt_dst;
1723         struct ifnet *destifp;
1724 #if defined(IPSEC) || defined(FAST_IPSEC)
1725         struct ifnet dummyifp;
1726 #endif
1727
1728         dest = 0;
1729         /*
1730          * Cache the destination address of the packet; this may be
1731          * changed by use of 'ipfw fwd'.
1732          */
1733         pkt_dst = next_hop ? next_hop->sin_addr : ip->ip_dst;
1734
1735 #ifdef DIAGNOSTIC
1736         if (ipprintfs)
1737                 printf("forward: src %lx dst %lx ttl %x\n",
1738                     (u_long)ip->ip_src.s_addr, (u_long)pkt_dst.s_addr,
1739                     ip->ip_ttl);
1740 #endif
1741
1742
1743         if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(pkt_dst) == 0) {
1744                 ipstat.ips_cantforward++;
1745                 m_freem(m);
1746                 return;
1747         }
1748 #ifdef IPSTEALTH
1749         if (!ipstealth) {
1750 #endif
1751                 if (ip->ip_ttl <= IPTTLDEC) {
1752                         icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
1753                             dest, 0);
1754                         return;
1755                 }
1756 #ifdef IPSTEALTH
1757         }
1758 #endif
1759
1760         sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
1761         if ((rt = ipforward_rt.ro_rt) == 0 ||
1762             pkt_dst.s_addr != sin->sin_addr.s_addr) {
1763                 if (ipforward_rt.ro_rt) {
1764                         RTFREE(ipforward_rt.ro_rt);
1765                         ipforward_rt.ro_rt = 0;
1766                 }
1767                 sin->sin_family = AF_INET;
1768                 sin->sin_len = sizeof(*sin);
1769                 sin->sin_addr = pkt_dst;
1770
1771                 rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
1772                 if (ipforward_rt.ro_rt == 0) {
1773                         icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1774                         return;
1775                 }
1776                 rt = ipforward_rt.ro_rt;
1777         }
1778
1779         /*
1780          * Save the IP header and at most 8 bytes of the payload,
1781          * in case we need to generate an ICMP message to the src.
1782          *
1783          * XXX this can be optimized a lot by saving the data in a local
1784          * buffer on the stack (72 bytes at most), and only allocating the
1785          * mbuf if really necessary. The vast majority of the packets
1786          * are forwarded without having to send an ICMP back (either
1787          * because unnecessary, or because rate limited), so we are
1788          * really we are wasting a lot of work here.
1789          *
1790          * We don't use m_copy() because it might return a reference
1791          * to a shared cluster. Both this function and ip_output()
1792          * assume exclusive access to the IP header in `m', so any
1793          * data in a cluster may change before we reach icmp_error().
1794          */
1795         MGET(mcopy, M_DONTWAIT, m->m_type);
1796         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
1797                 /*
1798                  * It's probably ok if the pkthdr dup fails (because
1799                  * the deep copy of the tag chain failed), but for now
1800                  * be conservative and just discard the copy since
1801                  * code below may some day want the tags.
1802                  */
1803                 m_free(mcopy);
1804                 mcopy = NULL;
1805         }
1806         if (mcopy != NULL) {
1807                 mcopy->m_len = imin((IP_VHL_HL(ip->ip_vhl) << 2) + 8,
1808                     (int)ip->ip_len);
1809                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
1810         }
1811
1812 #ifdef IPSTEALTH
1813         if (!ipstealth) {
1814 #endif
1815                 ip->ip_ttl -= IPTTLDEC;
1816 #ifdef IPSTEALTH
1817         }
1818 #endif
1819
1820         /*
1821          * If forwarding packet using same interface that it came in on,
1822          * perhaps should send a redirect to sender to shortcut a hop.
1823          * Only send redirect if source is sending directly to us,
1824          * and if packet was not source routed (or has any options).
1825          * Also, don't send redirect if forwarding using a default route
1826          * or a route modified by a redirect.
1827          */
1828         if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1829             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1830             satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1831             ipsendredirects && !srcrt && !next_hop) {
1832 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1833                 u_long src = ntohl(ip->ip_src.s_addr);
1834
1835                 if (RTA(rt) &&
1836                     (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1837                     if (rt->rt_flags & RTF_GATEWAY)
1838                         dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1839                     else
1840                         dest = pkt_dst.s_addr;
1841                     /* Router requirements says to only send host redirects */
1842                     type = ICMP_REDIRECT;
1843                     code = ICMP_REDIRECT_HOST;
1844 #ifdef DIAGNOSTIC
1845                     if (ipprintfs)
1846                         printf("redirect (%d) to %lx\n", code, (u_long)dest);
1847 #endif
1848                 }
1849         }
1850
1851     {
1852         struct m_hdr tag;
1853
1854         if (next_hop) {
1855                 /* Pass IPFORWARD info if available */
1856
1857                 tag.mh_type = MT_TAG;
1858                 tag.mh_flags = PACKET_TAG_IPFORWARD;
1859                 tag.mh_data = (caddr_t)next_hop;
1860                 tag.mh_next = m;
1861                 m = (struct mbuf *)&tag;
1862         }
1863         error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
1864                           IP_FORWARDING, 0, NULL);
1865     }
1866         if (error)
1867                 ipstat.ips_cantforward++;
1868         else {
1869                 ipstat.ips_forward++;
1870                 if (type)
1871                         ipstat.ips_redirectsent++;
1872                 else {
1873                         if (mcopy) {
1874                                 ipflow_create(&ipforward_rt, mcopy);
1875                                 m_freem(mcopy);
1876                         }
1877                         return;
1878                 }
1879         }
1880         if (mcopy == NULL)
1881                 return;
1882         destifp = NULL;
1883
1884         switch (error) {
1885
1886         case 0:                         /* forwarded, but need redirect */
1887                 /* type, code set above */
1888                 break;
1889
1890         case ENETUNREACH:               /* shouldn't happen, checked above */
1891         case EHOSTUNREACH:
1892         case ENETDOWN:
1893         case EHOSTDOWN:
1894         default:
1895                 type = ICMP_UNREACH;
1896                 code = ICMP_UNREACH_HOST;
1897                 break;
1898
1899         case EMSGSIZE:
1900                 type = ICMP_UNREACH;
1901                 code = ICMP_UNREACH_NEEDFRAG;
1902 #ifdef IPSEC
1903                 /*
1904                  * If the packet is routed over IPsec tunnel, tell the
1905                  * originator the tunnel MTU.
1906                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1907                  * XXX quickhack!!!
1908                  */
1909                 if (ipforward_rt.ro_rt) {
1910                         struct secpolicy *sp = NULL;
1911                         int ipsecerror;
1912                         int ipsechdr;
1913                         struct route *ro;
1914
1915                         sp = ipsec4_getpolicybyaddr(mcopy,
1916                                                     IPSEC_DIR_OUTBOUND,
1917                                                     IP_FORWARDING,
1918                                                     &ipsecerror);
1919
1920                         if (sp == NULL)
1921                                 destifp = ipforward_rt.ro_rt->rt_ifp;
1922                         else {
1923                                 /* count IPsec header size */
1924                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1925                                                          IPSEC_DIR_OUTBOUND,
1926                                                          NULL);
1927
1928                                 /*
1929                                  * find the correct route for outer IPv4
1930                                  * header, compute tunnel MTU.
1931                                  *
1932                                  * XXX BUG ALERT
1933                                  * The "dummyifp" code relies upon the fact
1934                                  * that icmp_error() touches only ifp->if_mtu.
1935                                  */
1936                                 /*XXX*/
1937                                 destifp = NULL;
1938                                 if (sp->req != NULL
1939                                  && sp->req->sav != NULL
1940                                  && sp->req->sav->sah != NULL) {
1941                                         ro = &sp->req->sav->sah->sa_route;
1942                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1943                                                 dummyifp.if_mtu =
1944                                                     ro->ro_rt->rt_ifp->if_mtu;
1945                                                 dummyifp.if_mtu -= ipsechdr;
1946                                                 destifp = &dummyifp;
1947                                         }
1948                                 }
1949
1950                                 key_freesp(sp);
1951                         }
1952                 }
1953 #elif FAST_IPSEC
1954                 /*
1955                  * If the packet is routed over IPsec tunnel, tell the
1956                  * originator the tunnel MTU.
1957                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1958                  * XXX quickhack!!!
1959                  */
1960                 if (ipforward_rt.ro_rt) {
1961                         struct secpolicy *sp = NULL;
1962                         int ipsecerror;
1963                         int ipsechdr;
1964                         struct route *ro;
1965
1966                         sp = ipsec_getpolicybyaddr(mcopy,
1967                                                    IPSEC_DIR_OUTBOUND,
1968                                                    IP_FORWARDING,
1969                                                    &ipsecerror);
1970
1971                         if (sp == NULL)
1972                                 destifp = ipforward_rt.ro_rt->rt_ifp;
1973                         else {
1974                                 /* count IPsec header size */
1975                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1976                                                          IPSEC_DIR_OUTBOUND,
1977                                                          NULL);
1978
1979                                 /*
1980                                  * find the correct route for outer IPv4
1981                                  * header, compute tunnel MTU.
1982                                  *
1983                                  * XXX BUG ALERT
1984                                  * The "dummyifp" code relies upon the fact
1985                                  * that icmp_error() touches only ifp->if_mtu.
1986                                  */
1987                                 /*XXX*/
1988                                 destifp = NULL;
1989                                 if (sp->req != NULL
1990                                  && sp->req->sav != NULL
1991                                  && sp->req->sav->sah != NULL) {
1992                                         ro = &sp->req->sav->sah->sa_route;
1993                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1994                                                 dummyifp.if_mtu =
1995                                                     ro->ro_rt->rt_ifp->if_mtu;
1996                                                 dummyifp.if_mtu -= ipsechdr;
1997                                                 destifp = &dummyifp;
1998                                         }
1999                                 }
2000
2001                                 KEY_FREESP(&sp);
2002                         }
2003                 }
2004 #else /* !IPSEC && !FAST_IPSEC */
2005                 if (ipforward_rt.ro_rt)
2006                         destifp = ipforward_rt.ro_rt->rt_ifp;
2007 #endif /*IPSEC*/
2008                 ipstat.ips_cantfrag++;
2009                 break;
2010
2011         case ENOBUFS:
2012                 /*
2013                  * A router should not generate ICMP_SOURCEQUENCH as
2014                  * required in RFC1812 Requirements for IP Version 4 Routers.
2015                  * Source quench could be a big problem under DoS attacks,
2016                  * or if the underlying interface is rate-limited.
2017                  * Those who need source quench packets may re-enable them
2018                  * via the net.inet.ip.sendsourcequench sysctl.
2019                  */
2020                 if (ip_sendsourcequench == 0) {
2021                         m_freem(mcopy);
2022                         return;
2023                 } else {
2024                         type = ICMP_SOURCEQUENCH;
2025                         code = 0;
2026                 }
2027                 break;
2028
2029         case EACCES:                    /* ipfw denied packet */
2030                 m_freem(mcopy);
2031                 return;
2032         }
2033         icmp_error(mcopy, type, code, dest, destifp);
2034 }
2035
2036 void
2037 ip_savecontrol(inp, mp, ip, m)
2038         struct inpcb *inp;
2039         struct mbuf **mp;
2040         struct ip *ip;
2041         struct mbuf *m;
2042 {
2043         if (inp->inp_socket->so_options & SO_TIMESTAMP) {
2044                 struct timeval tv;
2045
2046                 microtime(&tv);
2047                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
2048                         SCM_TIMESTAMP, SOL_SOCKET);
2049                 if (*mp)
2050                         mp = &(*mp)->m_next;
2051         }
2052         if (inp->inp_flags & INP_RECVDSTADDR) {
2053                 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
2054                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
2055                 if (*mp)
2056                         mp = &(*mp)->m_next;
2057         }
2058 #ifdef notyet
2059         /* XXX
2060          * Moving these out of udp_input() made them even more broken
2061          * than they already were.
2062          */
2063         /* options were tossed already */
2064         if (inp->inp_flags & INP_RECVOPTS) {
2065                 *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
2066                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
2067                 if (*mp)
2068                         mp = &(*mp)->m_next;
2069         }
2070         /* ip_srcroute doesn't do what we want here, need to fix */
2071         if (inp->inp_flags & INP_RECVRETOPTS) {
2072                 *mp = sbcreatecontrol((caddr_t) ip_srcroute(),
2073                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
2074                 if (*mp)
2075                         mp = &(*mp)->m_next;
2076         }
2077 #endif
2078         if (inp->inp_flags & INP_RECVIF) {
2079                 struct ifnet *ifp;
2080                 struct sdlbuf {
2081                         struct sockaddr_dl sdl;
2082                         u_char  pad[32];
2083                 } sdlbuf;
2084                 struct sockaddr_dl *sdp;
2085                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
2086
2087                 if (((ifp = m->m_pkthdr.rcvif))
2088                 && ( ifp->if_index && (ifp->if_index <= if_index))) {
2089                         sdp = (struct sockaddr_dl *)(ifnet_addrs
2090                                         [ifp->if_index - 1]->ifa_addr);
2091                         /*
2092                          * Change our mind and don't try copy.
2093                          */
2094                         if ((sdp->sdl_family != AF_LINK)
2095                         || (sdp->sdl_len > sizeof(sdlbuf))) {
2096                                 goto makedummy;
2097                         }
2098                         bcopy(sdp, sdl2, sdp->sdl_len);
2099                 } else {
2100 makedummy:
2101                         sdl2->sdl_len
2102                                 = offsetof(struct sockaddr_dl, sdl_data[0]);
2103                         sdl2->sdl_family = AF_LINK;
2104                         sdl2->sdl_index = 0;
2105                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
2106                 }
2107                 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
2108                         IP_RECVIF, IPPROTO_IP);
2109                 if (*mp)
2110                         mp = &(*mp)->m_next;
2111         }
2112 }
2113
2114 /*
2115  * XXX these routines are called from the upper part of the kernel.
2116  *
2117  * They could also be moved to ip_mroute.c, since all the RSVP
2118  *  handling is done there already.
2119  */
2120 int
2121 ip_rsvp_init(struct socket *so)
2122 {
2123         if (so->so_type != SOCK_RAW ||
2124             so->so_proto->pr_protocol != IPPROTO_RSVP)
2125                 return EOPNOTSUPP;
2126
2127         if (ip_rsvpd != NULL)
2128                 return EADDRINUSE;
2129
2130         ip_rsvpd = so;
2131         /*
2132          * This may seem silly, but we need to be sure we don't over-increment
2133          * the RSVP counter, in case something slips up.
2134          */
2135         if (!ip_rsvp_on) {
2136                 ip_rsvp_on = 1;
2137                 rsvp_on++;
2138         }
2139
2140         return 0;
2141 }
2142
2143 int
2144 ip_rsvp_done(void)
2145 {
2146         ip_rsvpd = NULL;
2147         /*
2148          * This may seem silly, but we need to be sure we don't over-decrement
2149          * the RSVP counter, in case something slips up.
2150          */
2151         if (ip_rsvp_on) {
2152                 ip_rsvp_on = 0;
2153                 rsvp_on--;
2154         }
2155         return 0;
2156 }
2157
2158 void
2159 rsvp_input(struct mbuf *m, int off, int proto)  /* XXX must fixup manually */
2160 {
2161         if (rsvp_input_p) { /* call the real one if loaded */
2162                 rsvp_input_p(m, off, proto);
2163                 return;
2164         }
2165
2166         /* Can still get packets with rsvp_on = 0 if there is a local member
2167          * of the group to which the RSVP packet is addressed.  But in this
2168          * case we want to throw the packet away.
2169          */
2170
2171         if (!rsvp_on) {
2172                 m_freem(m);
2173                 return;
2174         }
2175
2176         if (ip_rsvpd != NULL) {
2177                 rip_input(m, off, proto);
2178                 return;
2179         }
2180         /* Drop the packet */
2181         m_freem(m);
2182 }
2183