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  */
  36
  37 #define _IP_VHL
  38
  39 #include "opt_bootp.h"
  40 #include "opt_ipfw.h"
  41 #include "opt_ipdn.h"
  42 #include "opt_ipdivert.h"
  43 #include "opt_ipfilter.h"
  44 #include "opt_ipstealth.h"
  45 #include "opt_ipsec.h"
  46 #include "opt_random_ip_id.h"
  47
  48 #include <sys/param.h>
  49 #include <sys/systm.h>
  50 #include <sys/mbuf.h>
  51 #include <sys/malloc.h>
  52 #include <sys/domain.h>
  53 #include <sys/protosw.h>
  54 #include <sys/socket.h>
  55 #include <sys/time.h>
  56 #include <sys/kernel.h>
  57 #include <sys/syslog.h>
  58 #include <sys/sysctl.h>
  59
  60 #include <net/if.h>
  61 #include <net/if_types.h>
  62 #include <net/if_var.h>
  63 #include <net/if_dl.h>
  64 #include <net/route.h>
  65 #include <net/netisr.h>
  66 #include <net/intrq.h>
  67
  68 #include <netinet/in.h>
  69 #include <netinet/in_systm.h>
  70 #include <netinet/in_var.h>
  71 #include <netinet/ip.h>
  72 #include <netinet/in_pcb.h>
  73 #include <netinet/ip_var.h>
  74 #include <netinet/ip_icmp.h>
  75 #include <machine/in_cksum.h>
  76
  77 #include <netinet/ipprotosw.h>
  78
  79 #include <sys/socketvar.h>
  80
  81 #include <netinet/ip_fw.h>
  82 #include <netinet/ip_dummynet.h>
  83
  84 #ifdef IPSEC
  85 #include <netinet6/ipsec.h>
  86 #include <netkey/key.h>
  87 #endif
  88
  89 #ifdef FAST_IPSEC
  90 #include <netipsec/ipsec.h>
  91 #include <netipsec/key.h>
  92 #endif
  93
  94 int rsvp_on = 0;
  95 static int ip_rsvp_on;
  96 struct socket *ip_rsvpd;
  97
  98 int     ipforwarding = 0;
  99 SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
 100     &ipforwarding, 0, "Enable IP forwarding between interfaces");
 101
 102 static int      ipsendredirects = 1; /* XXX */
 103 SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
 104     &ipsendredirects, 0, "Enable sending IP redirects");
 105
 106 int     ip_defttl = IPDEFTTL;
 107 SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
 108     &ip_defttl, 0, "Maximum TTL on IP packets");
 109
 110 static int      ip_dosourceroute = 0;
 111 SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
 112     &ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
 113
 114 static int      ip_acceptsourceroute = 0;
 115 SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
 116     CTLFLAG_RW, &ip_acceptsourceroute, 0,
 117     "Enable accepting source routed IP packets");
 118
 119 static int      ip_keepfaith = 0;
 120 SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
 121         &ip_keepfaith,  0,
 122         "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
 123
 124 static int      nipq = 0;       /* total # of reass queues */
 125 static int      maxnipq;
 126 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
 127         &maxnipq, 0,
 128         "Maximum number of IPv4 fragment reassembly queue entries");
 129
 130 static int    maxfragsperpacket;
 131 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
 132         &maxfragsperpacket, 0,
 133         "Maximum number of IPv4 fragments allowed per packet");
 134
 135 static int      ip_sendsourcequench = 0;
 136 SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
 137         &ip_sendsourcequench, 0,
 138         "Enable the transmission of source quench packets");
 139
 140 /*
 141  * XXX - Setting ip_checkinterface mostly implements the receive side of
 142  * the Strong ES model described in RFC 1122, but since the routing table
 143  * and transmit implementation do not implement the Strong ES model,
 144  * setting this to 1 results in an odd hybrid.
 145  *
 146  * XXX - ip_checkinterface currently must be disabled if you use ipnat
 147  * to translate the destination address to another local interface.
 148  *
 149  * XXX - ip_checkinterface must be disabled if you add IP aliases
 150  * to the loopback interface instead of the interface where the
 151  * packets for those addresses are received.
 152  */
 153 static int      ip_checkinterface = 0;
 154 SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
 155     &ip_checkinterface, 0, "Verify packet arrives on correct interface");
 156
 157 #ifdef DIAGNOSTIC
 158 static int      ipprintfs = 0;
 159 #endif
 160
 161 static int      ipqmaxlen = IFQ_MAXLEN;
 162
 163 extern  struct domain inetdomain;
 164 extern  struct ipprotosw inetsw[];
 165 u_char  ip_protox[IPPROTO_MAX];
 166 struct  in_ifaddrhead in_ifaddrhead;            /* first inet address */
 167 struct  in_ifaddrhashhead *in_ifaddrhashtbl;    /* inet addr hash table */
 168 u_long  in_ifaddrhmask;                         /* mask for hash table */
 169 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
 170     &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
 171 SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
 172     &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
 173
 174 struct ipstat ipstat;
 175 SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
 176     &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)");
 177
 178 /* Packet reassembly stuff */
 179 #define IPREASS_NHASH_LOG2      6
 180 #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
 181 #define IPREASS_HMASK           (IPREASS_NHASH - 1)
 182 #define IPREASS_HASH(x,y) \
 183         (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
 184
 185 static struct ipq ipq[IPREASS_NHASH];
 186 const  int    ipintrq_present = 1;
 187
 188 #ifdef IPCTL_DEFMTU
 189 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
 190     &ip_mtu, 0, "Default MTU");
 191 #endif
 192
 193 #ifdef IPSTEALTH
 194 static int      ipstealth = 0;
 195 SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
 196     &ipstealth, 0, "");
 197 #endif
 198
 199
 200 /* Firewall hooks */
 201 ip_fw_chk_t *ip_fw_chk_ptr;
 202 int fw_enable = 1 ;
 203 int fw_one_pass = 1;
 204
 205 /* Dummynet hooks */
 206 ip_dn_io_t *ip_dn_io_ptr;
 207
 208 int (*fr_checkp) __P((struct ip *, int, struct ifnet *, int, struct mbuf **)) = NULL;
 209
 210 /*
 211  * XXX this is ugly -- the following two global variables are
 212  * used to store packet state while it travels through the stack.
 213  * Note that the code even makes assumptions on the size and
 214  * alignment of fields inside struct ip_srcrt so e.g. adding some
 215  * fields will break the code. This needs to be fixed.
 216  *
 217  * We need to save the IP options in case a protocol wants to respond
 218  * to an incoming packet over the same route if the packet got here
 219  * using IP source routing.  This allows connection establishment and
 220  * maintenance when the remote end is on a network that is not known
 221  * to us.
 222  */
 223 static int      ip_nhops = 0;
 224 static  struct ip_srcrt {
 225         struct  in_addr dst;                    /* final destination */
 226         char    nop;                            /* one NOP to align */
 227         char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
 228         struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
 229 } ip_srcrt;
 230
 231 static void     save_rte(u_char *, struct in_addr);
 232 static int      ip_dooptions(struct mbuf *m, int,
 233                         struct sockaddr_in *next_hop);
 234 static void     ip_forward(struct mbuf *m, int srcrt,
 235                         struct sockaddr_in *next_hop);
 236 static void     ip_freef(struct ipq *);
 237 static struct   mbuf *ip_reass(struct mbuf *, struct ipq *,
 238                 struct ipq *, u_int32_t *, u_int16_t *);
 239 static void     ipintr(void);
 240
 241 /*
 242  * IP initialization: fill in IP protocol switch table.
 243  * All protocols not implemented in kernel go to raw IP protocol handler.
 244  */
 245 void
 246 ip_init()
 247 {
 248         register struct ipprotosw *pr;
 249         register int i;
 250
 251         TAILQ_INIT(&in_ifaddrhead);
 252         in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask);
 253         pr = (struct ipprotosw *)pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 254         if (pr == 0)
 255                 panic("ip_init");
 256         for (i = 0; i < IPPROTO_MAX; i++)
 257                 ip_protox[i] = pr - inetsw;
 258         for (pr = (struct ipprotosw *)inetdomain.dom_protosw;
 259             pr < (struct ipprotosw *)inetdomain.dom_protoswNPROTOSW; pr++)
 260                 if (pr->pr_domain->dom_family == PF_INET &&
 261                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
 262                         ip_protox[pr->pr_protocol] = pr - inetsw;
 263
 264         for (i = 0; i < IPREASS_NHASH; i++)
 265             ipq[i].next = ipq[i].prev = &ipq[i];
 266
 267         maxnipq = nmbclusters / 32;
 268         maxfragsperpacket = 16;
 269
 270 #ifndef RANDOM_IP_ID
 271         ip_id = time_second & 0xffff;
 272 #endif
 273         ipintrq.ifq_maxlen = ipqmaxlen;
 274
 275         register_netisr(NETISR_IP, ipintr);
 276 }
 277
 278 /*
 279  * XXX watch out this one. It is perhaps used as a cache for
 280  * the most recently used route ? it is cleared in in_addroute()
 281  * when a new route is successfully created.
 282  */
 283 struct  route ipforward_rt;
 284 static struct   sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
 285
 286 /*
 287  * Ip input routine.  Checksum and byte swap header.  If fragmented
 288  * try to reassemble.  Process options.  Pass to next level.
 289  */
 290 void
 291 ip_input(struct mbuf *m)
 292 {
 293         struct ip *ip;
 294         struct ipq *fp;
 295         struct in_ifaddr *ia = NULL;
 296         struct ifaddr *ifa;
 297         int    i, hlen, checkif;
 298         u_short sum;
 299         struct in_addr pkt_dst;
 300         u_int32_t divert_info = 0;              /* packet divert/tee info */
 301         struct ip_fw_args args;
 302 #ifdef FAST_IPSEC
 303         struct m_tag *mtag;
 304         struct tdb_ident *tdbi;
 305         struct secpolicy *sp;
 306         int s, error;
 307 #endif /* FAST_IPSEC */
 308
 309         args.eh = NULL;
 310         args.oif = NULL;
 311         args.rule = NULL;
 312         args.divert_rule = 0;                   /* divert cookie */
 313         args.next_hop = NULL;
 314
 315         /* Grab info from MT_TAG mbufs prepended to the chain.  */
 316         for (; m && m->m_type == MT_TAG; m = m->m_next) {
 317                 switch(m->_m_tag_id) {
 318                 default:
 319                         printf("ip_input: unrecognised MT_TAG tag %d\n",
 320                             m->_m_tag_id);
 321                         break;
 322
 323                 case PACKET_TAG_DUMMYNET:
 324                         args.rule = ((struct dn_pkt *)m)->rule;
 325                         break;
 326
 327                 case PACKET_TAG_DIVERT:
 328                         args.divert_rule = (int)m->m_hdr.mh_data & 0xffff;
 329                         break;
 330
 331                 case PACKET_TAG_IPFORWARD:
 332                         args.next_hop = (struct sockaddr_in *)m->m_hdr.mh_data;
 333                         break;
 334                 }
 335         }
 336
 337         KASSERT(m != NULL && (m->m_flags & M_PKTHDR) != 0,
 338             ("ip_input: no HDR"));
 339
 340         if (args.rule) {        /* dummynet already filtered us */
 341                 ip = mtod(m, struct ip *);
 342                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 343                 goto iphack ;
 344         }
 345
 346         ipstat.ips_total++;
 347
 348         if (m->m_pkthdr.len < sizeof(struct ip))
 349                 goto tooshort;
 350
 351         if (m->m_len < sizeof (struct ip) &&
 352             (m = m_pullup(m, sizeof (struct ip))) == 0) {
 353                 ipstat.ips_toosmall++;
 354                 return;
 355         }
 356         ip = mtod(m, struct ip *);
 357
 358         if (IP_VHL_V(ip->ip_vhl) != IPVERSION) {
 359                 ipstat.ips_badvers++;
 360                 goto bad;
 361         }
 362
 363         hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 364         if (hlen < sizeof(struct ip)) { /* minimum header length */
 365                 ipstat.ips_badhlen++;
 366                 goto bad;
 367         }
 368         if (hlen > m->m_len) {
 369                 if ((m = m_pullup(m, hlen)) == 0) {
 370                         ipstat.ips_badhlen++;
 371                         return;
 372                 }
 373                 ip = mtod(m, struct ip *);
 374         }
 375
 376         /* 127/8 must not appear on wire - RFC1122 */
 377         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
 378             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
 379                 if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
 380                         ipstat.ips_badaddr++;
 381                         goto bad;
 382                 }
 383         }
 384
 385         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
 386                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
 387         } else {
 388                 if (hlen == sizeof(struct ip)) {
 389                         sum = in_cksum_hdr(ip);
 390                 } else {
 391                         sum = in_cksum(m, hlen);
 392                 }
 393         }
 394         if (sum) {
 395                 ipstat.ips_badsum++;
 396                 goto bad;
 397         }
 398
 399         /*
 400          * Convert fields to host representation.
 401          */
 402         ip->ip_len = ntohs(ip->ip_len);
 403         if (ip->ip_len < hlen) {
 404                 ipstat.ips_badlen++;
 405                 goto bad;
 406         }
 407         ip->ip_off = ntohs(ip->ip_off);
 408
 409         /*
 410          * Check that the amount of data in the buffers
 411          * is as at least much as the IP header would have us expect.
 412          * Trim mbufs if longer than we expect.
 413          * Drop packet if shorter than we expect.
 414          */
 415         if (m->m_pkthdr.len < ip->ip_len) {
 416 tooshort:
 417                 ipstat.ips_tooshort++;
 418                 goto bad;
 419         }
 420         if (m->m_pkthdr.len > ip->ip_len) {
 421                 if (m->m_len == m->m_pkthdr.len) {
 422                         m->m_len = ip->ip_len;
 423                         m->m_pkthdr.len = ip->ip_len;
 424                 } else
 425                         m_adj(m, ip->ip_len - m->m_pkthdr.len);
 426         }
 427 #if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
 428         /*
 429          * Bypass packet filtering for packets from a tunnel (gif).
 430          */
 431         if (ipsec_gethist(m, NULL))
 432                 goto pass;
 433 #endif
 434
 435         /*
 436          * IpHack's section.
 437          * Right now when no processing on packet has done
 438          * and it is still fresh out of network we do our black
 439          * deals with it.
 440          * - Firewall: deny/allow/divert
 441          * - Xlate: translate packet's addr/port (NAT).
 442          * - Pipe: pass pkt through dummynet.
 443          * - Wrap: fake packet's addr/port <unimpl.>
 444          * - Encapsulate: put it in another IP and send out. <unimp.>
 445          */
 446
 447 iphack:
 448         /*
 449          * Check if we want to allow this packet to be processed.
 450          * Consider it to be bad if not.
 451          */
 452         if (fr_checkp) {
 453                 struct  mbuf    *m1 = m;
 454
 455                 if ((*fr_checkp)(ip, hlen, m->m_pkthdr.rcvif, 0, &m1) || !m1)
 456                         return;
 457                 ip = mtod(m = m1, struct ip *);
 458         }
 459         if (fw_enable && IPFW_LOADED) {
 460                 /*
 461                  * If we've been forwarded from the output side, then
 462                  * skip the firewall a second time
 463                  */
 464                 if (args.next_hop)
 465                         goto ours;
 466
 467                 args.m = m;
 468                 i = ip_fw_chk_ptr(&args);
 469                 m = args.m;
 470
 471                 if ( (i & IP_FW_PORT_DENY_FLAG) || m == NULL) { /* drop */
 472                         if (m)
 473                                 m_freem(m);
 474                         return;
 475                 }
 476                 ip = mtod(m, struct ip *); /* just in case m changed */
 477                 if (i == 0 && args.next_hop == NULL)    /* common case */
 478                         goto pass;
 479                 if (DUMMYNET_LOADED && (i & IP_FW_PORT_DYNT_FLAG) != 0) {
 480                         /* Send packet to the appropriate pipe */
 481                         ip_dn_io_ptr(m, i&0xffff, DN_TO_IP_IN, &args);
 482                         return;
 483                 }
 484 #ifdef IPDIVERT
 485                 if (i != 0 && (i & IP_FW_PORT_DYNT_FLAG) == 0) {
 486                         /* Divert or tee packet */
 487                         divert_info = i;
 488                         goto ours;
 489                 }
 490 #endif
 491                 if (i == 0 && args.next_hop != NULL)
 492                         goto pass;
 493                 /*
 494                  * if we get here, the packet must be dropped
 495                  */
 496                 m_freem(m);
 497                 return;
 498         }
 499 pass:
 500
 501         /*
 502          * Process options and, if not destined for us,
 503          * ship it on.  ip_dooptions returns 1 when an
 504          * error was detected (causing an icmp message
 505          * to be sent and the original packet to be freed).
 506          */
 507         ip_nhops = 0;           /* for source routed packets */
 508         if (hlen > sizeof (struct ip) && ip_dooptions(m, 0, args.next_hop))
 509                 return;
 510
 511         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
 512          * matter if it is destined to another node, or whether it is
 513          * a multicast one, RSVP wants it! and prevents it from being forwarded
 514          * anywhere else. Also checks if the rsvp daemon is running before
 515          * grabbing the packet.
 516          */
 517         if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
 518                 goto ours;
 519
 520         /*
 521          * Check our list of addresses, to see if the packet is for us.
 522          * If we don't have any addresses, assume any unicast packet
 523          * we receive might be for us (and let the upper layers deal
 524          * with it).
 525          */
 526         if (TAILQ_EMPTY(&in_ifaddrhead) &&
 527             (m->m_flags & (M_MCAST|M_BCAST)) == 0)
 528                 goto ours;
 529
 530         /*
 531          * Cache the destination address of the packet; this may be
 532          * changed by use of 'ipfw fwd'.
 533          */
 534         pkt_dst = args.next_hop ? args.next_hop->sin_addr : ip->ip_dst;
 535
 536         /*
 537          * Enable a consistency check between the destination address
 538          * and the arrival interface for a unicast packet (the RFC 1122
 539          * strong ES model) if IP forwarding is disabled and the packet
 540          * is not locally generated and the packet is not subject to
 541          * 'ipfw fwd'.
 542          *
 543          * XXX - Checking also should be disabled if the destination
 544          * address is ipnat'ed to a different interface.
 545          *
 546          * XXX - Checking is incompatible with IP aliases added
 547          * to the loopback interface instead of the interface where
 548          * the packets are received.
 549          */
 550         checkif = ip_checkinterface && (ipforwarding == 0) &&
 551             m->m_pkthdr.rcvif != NULL &&
 552             ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) &&
 553             (args.next_hop == NULL);
 554
 555         /*
 556          * Check for exact addresses in the hash bucket.
 557          */
 558         LIST_FOREACH(ia, INADDR_HASH(pkt_dst.s_addr), ia_hash) {
 559                 /*
 560                  * If the address matches, verify that the packet
 561                  * arrived via the correct interface if checking is
 562                  * enabled.
 563                  */
 564                 if (IA_SIN(ia)->sin_addr.s_addr == pkt_dst.s_addr &&
 565                     (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
 566                         goto ours;
 567         }
 568         /*
 569          * Check for broadcast addresses.
 570          *
 571          * Only accept broadcast packets that arrive via the matching
 572          * interface.  Reception of forwarded directed broadcasts would
 573          * be handled via ip_forward() and ether_output() with the loopback
 574          * into the stack for SIMPLEX interfaces handled by ether_output().
 575          */
 576         if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
 577                 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
 578                         if (ifa->ifa_addr->sa_family != AF_INET)
 579                                 continue;
 580                         ia = ifatoia(ifa);
 581                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 582                             pkt_dst.s_addr)
 583                                 goto ours;
 584                         if (ia->ia_netbroadcast.s_addr == pkt_dst.s_addr)
 585                                 goto ours;
 586 #ifdef BOOTP_COMPAT
 587                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
 588                                 goto ours;
 589 #endif
 590                 }
 591         }
 592         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
 593                 struct in_multi *inm;
 594                 if (ip_mrouter) {
 595                         /*
 596                          * If we are acting as a multicast router, all
 597                          * incoming multicast packets are passed to the
 598                          * kernel-level multicast forwarding function.
 599                          * The packet is returned (relatively) intact; if
 600                          * ip_mforward() returns a non-zero value, the packet
 601                          * must be discarded, else it may be accepted below.
 602                          */
 603                         if (ip_mforward &&
 604                             ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
 605                                 ipstat.ips_cantforward++;
 606                                 m_freem(m);
 607                                 return;
 608                         }
 609
 610                         /*
 611                          * The process-level routing daemon needs to receive
 612                          * all multicast IGMP packets, whether or not this
 613                          * host belongs to their destination groups.
 614                          */
 615                         if (ip->ip_p == IPPROTO_IGMP)
 616                                 goto ours;
 617                         ipstat.ips_forward++;
 618                 }
 619                 /*
 620                  * See if we belong to the destination multicast group on the
 621                  * arrival interface.
 622                  */
 623                 IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
 624                 if (inm == NULL) {
 625                         ipstat.ips_notmember++;
 626                         m_freem(m);
 627                         return;
 628                 }
 629                 goto ours;
 630         }
 631         if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
 632                 goto ours;
 633         if (ip->ip_dst.s_addr == INADDR_ANY)
 634                 goto ours;
 635
 636         /*
 637          * FAITH(Firewall Aided Internet Translator)
 638          */
 639         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 640                 if (ip_keepfaith) {
 641                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
 642                                 goto ours;
 643                 }
 644                 m_freem(m);
 645                 return;
 646         }
 647
 648         /*
 649          * Not for us; forward if possible and desirable.
 650          */
 651         if (ipforwarding == 0) {
 652                 ipstat.ips_cantforward++;
 653                 m_freem(m);
 654         } else {
 655 #ifdef IPSEC
 656                 /*
 657                  * Enforce inbound IPsec SPD.
 658                  */
 659                 if (ipsec4_in_reject(m, NULL)) {
 660                         ipsecstat.in_polvio++;
 661                         goto bad;
 662                 }
 663 #endif /* IPSEC */
 664 #ifdef FAST_IPSEC
 665                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 666                 s = splnet();
 667                 if (mtag != NULL) {
 668                         tdbi = (struct tdb_ident *)(mtag + 1);
 669                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 670                 } else {
 671                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 672                                                    IP_FORWARDING, &error);
 673                 }
 674                 if (sp == NULL) {       /* NB: can happen if error */
 675                         splx(s);
 676                         /*XXX error stat???*/
 677                         DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
 678                         goto bad;
 679                 }
 680
 681                 /*
 682                  * Check security policy against packet attributes.
 683                  */
 684                 error = ipsec_in_reject(sp, m);
 685                 KEY_FREESP(&sp);
 686                 splx(s);
 687                 if (error) {
 688                         ipstat.ips_cantforward++;
 689                         goto bad;
 690                 }
 691 #endif /* FAST_IPSEC */
 692                 ip_forward(m, 0, args.next_hop);
 693         }
 694         return;
 695
 696 ours:
 697 #ifdef IPSTEALTH
 698         /*
 699          * IPSTEALTH: Process non-routing options only
 700          * if the packet is destined for us.
 701          */
 702         if (ipstealth && hlen > sizeof (struct ip) &&
 703             ip_dooptions(m, 1, args.next_hop))
 704                 return;
 705 #endif /* IPSTEALTH */
 706
 707         /* Count the packet in the ip address stats */
 708         if (ia != NULL) {
 709                 ia->ia_ifa.if_ipackets++;
 710                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
 711         }
 712
 713         /*
 714          * If offset or IP_MF are set, must reassemble.
 715          * Otherwise, nothing need be done.
 716          * (We could look in the reassembly queue to see
 717          * if the packet was previously fragmented,
 718          * but it's not worth the time; just let them time out.)
 719          */
 720         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
 721
 722                 /* If maxnipq is 0, never accept fragments. */
 723                 if (maxnipq == 0) {
 724                         ipstat.ips_fragments++;
 725                         ipstat.ips_fragdropped++;
 726                         goto bad;
 727                 }
 728
 729                 sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
 730                 /*
 731                  * Look for queue of fragments
 732                  * of this datagram.
 733                  */
 734                 for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next)
 735                         if (ip->ip_id == fp->ipq_id &&
 736                             ip->ip_src.s_addr == fp->ipq_src.s_addr &&
 737                             ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
 738                             ip->ip_p == fp->ipq_p)
 739                                 goto found;
 740
 741                 fp = 0;
 742
 743                 /*
 744                  * Enforce upper bound on number of fragmented packets
 745                  * for which we attempt reassembly;
 746                  * If maxnipq is -1, accept all fragments without limitation.
 747                  */
 748                 if ((nipq > maxnipq) && (maxnipq > 0)) {
 749                     /*
 750                      * drop something from the tail of the current queue
 751                      * before proceeding further
 752                      */
 753                     if (ipq[sum].prev == &ipq[sum]) {   /* gak */
 754                         for (i = 0; i < IPREASS_NHASH; i++) {
 755                             if (ipq[i].prev != &ipq[i]) {
 756                                 ipstat.ips_fragtimeout +=
 757                                     ipq[i].prev->ipq_nfrags;
 758                                 ip_freef(ipq[i].prev);
 759                                 break;
 760                             }
 761                         }
 762                     } else {
 763                         ipstat.ips_fragtimeout += ipq[sum].prev->ipq_nfrags;
 764                         ip_freef(ipq[sum].prev);
 765                     }
 766                 }
 767 found:
 768                 /*
 769                  * Adjust ip_len to not reflect header,
 770                  * convert offset of this to bytes.
 771                  */
 772                 ip->ip_len -= hlen;
 773                 if (ip->ip_off & IP_MF) {
 774                         /*
 775                          * Make sure that fragments have a data length
 776                          * that's a non-zero multiple of 8 bytes.
 777                          */
 778                         if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
 779                                 ipstat.ips_toosmall++; /* XXX */
 780                                 goto bad;
 781                         }
 782                         m->m_flags |= M_FRAG;
 783                 } else
 784                         m->m_flags &= ~M_FRAG;
 785                 ip->ip_off <<= 3;
 786
 787                 /*
 788                  * Attempt reassembly; if it succeeds, proceed.
 789                  * ip_reass() will return a different mbuf, and update
 790                  * the divert info in divert_info and args.divert_rule.
 791                  */
 792                 ipstat.ips_fragments++;
 793                 m->m_pkthdr.header = ip;
 794                 m = ip_reass(m,
 795                     fp, &ipq[sum], &divert_info, &args.divert_rule);
 796                 if (m == 0)
 797                         return;
 798                 ipstat.ips_reassembled++;
 799                 ip = mtod(m, struct ip *);
 800                 /* Get the header length of the reassembled packet */
 801                 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 802 #ifdef IPDIVERT
 803                 /* Restore original checksum before diverting packet */
 804                 if (divert_info != 0) {
 805                         ip->ip_len += hlen;
 806                         ip->ip_len = htons(ip->ip_len);
 807                         ip->ip_off = htons(ip->ip_off);
 808                         ip->ip_sum = 0;
 809                         if (hlen == sizeof(struct ip))
 810                                 ip->ip_sum = in_cksum_hdr(ip);
 811                         else
 812                                 ip->ip_sum = in_cksum(m, hlen);
 813                         ip->ip_off = ntohs(ip->ip_off);
 814                         ip->ip_len = ntohs(ip->ip_len);
 815                         ip->ip_len -= hlen;
 816                 }
 817 #endif
 818         } else
 819                 ip->ip_len -= hlen;
 820
 821 #ifdef IPDIVERT
 822         /*
 823          * Divert or tee packet to the divert protocol if required.
 824          */
 825         if (divert_info != 0) {
 826                 struct mbuf *clone = NULL;
 827
 828                 /* Clone packet if we're doing a 'tee' */
 829                 if ((divert_info & IP_FW_PORT_TEE_FLAG) != 0)
 830                         clone = m_dup(m, M_DONTWAIT);
 831
 832                 /* Restore packet header fields to original values */
 833                 ip->ip_len += hlen;
 834                 ip->ip_len = htons(ip->ip_len);
 835                 ip->ip_off = htons(ip->ip_off);
 836
 837                 /* Deliver packet to divert input routine */
 838                 divert_packet(m, 1, divert_info & 0xffff, args.divert_rule);
 839                 ipstat.ips_delivered++;
 840
 841                 /* If 'tee', continue with original packet */
 842                 if (clone == NULL)
 843                         return;
 844                 m = clone;
 845                 ip = mtod(m, struct ip *);
 846                 ip->ip_len += hlen;
 847                 /*
 848                  * Jump backwards to complete processing of the
 849                  * packet. But first clear divert_info to avoid
 850                  * entering this block again.
 851                  * We do not need to clear args.divert_rule
 852                  * or args.next_hop as they will not be used.
 853                  */
 854                 divert_info = 0;
 855                 goto pass;
 856         }
 857 #endif
 858
 859 #ifdef IPSEC
 860         /*
 861          * enforce IPsec policy checking if we are seeing last header.
 862          * note that we do not visit this with protocols with pcb layer
 863          * code - like udp/tcp/raw ip.
 864          */
 865         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
 866             ipsec4_in_reject(m, NULL)) {
 867                 ipsecstat.in_polvio++;
 868                 goto bad;
 869         }
 870 #endif
 871 #if FAST_IPSEC
 872         /*
 873          * enforce IPsec policy checking if we are seeing last header.
 874          * note that we do not visit this with protocols with pcb layer
 875          * code - like udp/tcp/raw ip.
 876          */
 877         if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
 878                 /*
 879                  * Check if the packet has already had IPsec processing
 880                  * done.  If so, then just pass it along.  This tag gets
 881                  * set during AH, ESP, etc. input handling, before the
 882                  * packet is returned to the ip input queue for delivery.
 883                  */
 884                 mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
 885                 s = splnet();
 886                 if (mtag != NULL) {
 887                         tdbi = (struct tdb_ident *)(mtag + 1);
 888                         sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
 889                 } else {
 890                         sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
 891                                                    IP_FORWARDING, &error);
 892                 }
 893                 if (sp != NULL) {
 894                         /*
 895                          * Check security policy against packet attributes.
 896                          */
 897                         error = ipsec_in_reject(sp, m);
 898                         KEY_FREESP(&sp);
 899                 } else {
 900                         /* XXX error stat??? */
 901                         error = EINVAL;
 902 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
 903                         goto bad;
 904                 }
 905                 splx(s);
 906                 if (error)
 907                         goto bad;
 908         }
 909 #endif /* FAST_IPSEC */
 910
 911         /*
 912          * Switch out to protocol's input routine.
 913          */
 914         ipstat.ips_delivered++;
 915         if (args.next_hop && ip->ip_p == IPPROTO_TCP) {
 916                 /* TCP needs IPFORWARD info if available */
 917                 struct m_hdr tag;
 918
 919                 tag.mh_type = MT_TAG;
 920                 tag.mh_flags = PACKET_TAG_IPFORWARD;
 921                 tag.mh_data = (caddr_t)args.next_hop;
 922                 tag.mh_next = m;
 923
 924                 (*inetsw[ip_protox[ip->ip_p]].pr_input)(
 925                         (struct mbuf *)&tag, hlen, ip->ip_p);
 926         } else
 927                 (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen, ip->ip_p);
 928         return;
 929 bad:
 930         m_freem(m);
 931 }
 932
 933 /*
 934  * IP software interrupt routine - to go away sometime soon
 935  */
 936 static void
 937 ipintr(void)
 938 {
 939         int s;
 940         struct mbuf *m;
 941
 942         while(1) {
 943                 s = splimp();
 944                 IF_DEQUEUE(&ipintrq, m);
 945                 splx(s);
 946                 if (m == 0)
 947                         return;
 948                 ip_input(m);
 949         }
 950 }
 951
 952 /*
 953  * Take incoming datagram fragment and try to reassemble it into
 954  * whole datagram.  If a chain for reassembly of this datagram already
 955  * exists, then it is given as fp; otherwise have to make a chain.
 956  *
 957  * When IPDIVERT enabled, keep additional state with each packet that
 958  * tells us if we need to divert or tee the packet we're building.
 959  * In particular, *divinfo includes the port and TEE flag,
 960  * *divert_rule is the number of the matching rule.
 961  */
 962
 963 static struct mbuf *
 964 ip_reass(struct mbuf *m, struct ipq *fp, struct ipq *where,
 965         u_int32_t *divinfo, u_int16_t *divert_rule)
 966 {
 967         struct ip *ip = mtod(m, struct ip *);
 968         register struct mbuf *p = 0, *q, *nq;
 969         struct mbuf *t;
 970         int hlen = IP_VHL_HL(ip->ip_vhl) << 2;
 971         int i, next;
 972
 973         /*
 974          * Presence of header sizes in mbufs
 975          * would confuse code below.
 976          */
 977         m->m_data += hlen;
 978         m->m_len -= hlen;
 979
 980         /*
 981          * If first fragment to arrive, create a reassembly queue.
 982          */
 983         if (fp == 0) {
 984                 if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
 985                         goto dropfrag;
 986                 fp = mtod(t, struct ipq *);
 987                 insque(fp, where);
 988                 nipq++;
 989                 fp->ipq_nfrags = 1;
 990                 fp->ipq_ttl = IPFRAGTTL;
 991                 fp->ipq_p = ip->ip_p;
 992                 fp->ipq_id = ip->ip_id;
 993                 fp->ipq_src = ip->ip_src;
 994                 fp->ipq_dst = ip->ip_dst;
 995                 fp->ipq_frags = m;
 996                 m->m_nextpkt = NULL;
 997 #ifdef IPDIVERT
 998                 fp->ipq_div_info = 0;
 999                 fp->ipq_div_cookie = 0;
1000 #endif
1001                 goto inserted;
1002         } else {
1003                 fp->ipq_nfrags++;
1004         }
1005
1006 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.header))
1007
1008         /*
1009          * Find a segment which begins after this one does.
1010          */
1011         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
1012                 if (GETIP(q)->ip_off > ip->ip_off)
1013                         break;
1014
1015         /*
1016          * If there is a preceding segment, it may provide some of
1017          * our data already.  If so, drop the data from the incoming
1018          * segment.  If it provides all of our data, drop us, otherwise
1019          * stick new segment in the proper place.
1020          *
1021          * If some of the data is dropped from the the preceding
1022          * segment, then it's checksum is invalidated.
1023          */
1024         if (p) {
1025                 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
1026                 if (i > 0) {
1027                         if (i >= ip->ip_len)
1028                                 goto dropfrag;
1029                         m_adj(m, i);
1030                         m->m_pkthdr.csum_flags = 0;
1031                         ip->ip_off += i;
1032                         ip->ip_len -= i;
1033                 }
1034                 m->m_nextpkt = p->m_nextpkt;
1035                 p->m_nextpkt = m;
1036         } else {
1037                 m->m_nextpkt = fp->ipq_frags;
1038                 fp->ipq_frags = m;
1039         }
1040
1041         /*
1042          * While we overlap succeeding segments trim them or,
1043          * if they are completely covered, dequeue them.
1044          */
1045         for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
1046              q = nq) {
1047                 i = (ip->ip_off + ip->ip_len) -
1048                     GETIP(q)->ip_off;
1049                 if (i < GETIP(q)->ip_len) {
1050                         GETIP(q)->ip_len -= i;
1051                         GETIP(q)->ip_off += i;
1052                         m_adj(q, i);
1053                         q->m_pkthdr.csum_flags = 0;
1054                         break;
1055                 }
1056                 nq = q->m_nextpkt;
1057                 m->m_nextpkt = nq;
1058                 ipstat.ips_fragdropped++;
1059                 fp->ipq_nfrags--;
1060                 m_freem(q);
1061         }
1062
1063 inserted:
1064
1065 #ifdef IPDIVERT
1066         /*
1067          * Transfer firewall instructions to the fragment structure.
1068          * Only trust info in the fragment at offset 0.
1069          */
1070         if (ip->ip_off == 0) {
1071                 fp->ipq_div_info = *divinfo;
1072                 fp->ipq_div_cookie = *divert_rule;
1073         }
1074         *divinfo = 0;
1075         *divert_rule = 0;
1076 #endif
1077
1078         /*
1079          * Check for complete reassembly and perform frag per packet
1080          * limiting.
1081          *
1082          * Frag limiting is performed here so that the nth frag has
1083          * a chance to complete the packet before we drop the packet.
1084          * As a result, n+1 frags are actually allowed per packet, but
1085          * only n will ever be stored. (n = maxfragsperpacket.)
1086          *
1087          */
1088         next = 0;
1089         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
1090                 if (GETIP(q)->ip_off != next) {
1091                         if (fp->ipq_nfrags > maxfragsperpacket) {
1092                                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1093                                 ip_freef(fp);
1094                         }
1095                         return (0);
1096                 }
1097                 next += GETIP(q)->ip_len;
1098         }
1099         /* Make sure the last packet didn't have the IP_MF flag */
1100         if (p->m_flags & M_FRAG) {
1101                 if (fp->ipq_nfrags > maxfragsperpacket) {
1102                         ipstat.ips_fragdropped += fp->ipq_nfrags;
1103                         ip_freef(fp);
1104                 }
1105                 return (0);
1106         }
1107
1108         /*
1109          * Reassembly is complete.  Make sure the packet is a sane size.
1110          */
1111         q = fp->ipq_frags;
1112         ip = GETIP(q);
1113         if (next + (IP_VHL_HL(ip->ip_vhl) << 2) > IP_MAXPACKET) {
1114                 ipstat.ips_toolong++;
1115                 ipstat.ips_fragdropped += fp->ipq_nfrags;
1116                 ip_freef(fp);
1117                 return (0);
1118         }
1119
1120         /*
1121          * Concatenate fragments.
1122          */
1123         m = q;
1124         t = m->m_next;
1125         m->m_next = 0;
1126         m_cat(m, t);
1127         nq = q->m_nextpkt;
1128         q->m_nextpkt = 0;
1129         for (q = nq; q != NULL; q = nq) {
1130                 nq = q->m_nextpkt;
1131                 q->m_nextpkt = NULL;
1132                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
1133                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
1134                 m_cat(m, q);
1135         }
1136
1137 #ifdef IPDIVERT
1138         /*
1139          * Extract firewall instructions from the fragment structure.
1140          */
1141         *divinfo = fp->ipq_div_info;
1142         *divert_rule = fp->ipq_div_cookie;
1143 #endif
1144
1145         /*
1146          * Create header for new ip packet by
1147          * modifying header of first packet;
1148          * dequeue and discard fragment reassembly header.
1149          * Make header visible.
1150          */
1151         ip->ip_len = next;
1152         ip->ip_src = fp->ipq_src;
1153         ip->ip_dst = fp->ipq_dst;
1154         remque(fp);
1155         nipq--;
1156         (void) m_free(dtom(fp));
1157         m->m_len += (IP_VHL_HL(ip->ip_vhl) << 2);
1158         m->m_data -= (IP_VHL_HL(ip->ip_vhl) << 2);
1159         /* some debugging cruft by sklower, below, will go away soon */
1160         if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
1161                 register int plen = 0;
1162                 for (t = m; t; t = t->m_next)
1163                         plen += t->m_len;
1164                 m->m_pkthdr.len = plen;
1165         }
1166         return (m);
1167
1168 dropfrag:
1169 #ifdef IPDIVERT
1170         *divinfo = 0;
1171         *divert_rule = 0;
1172 #endif
1173         ipstat.ips_fragdropped++;
1174         if (fp != 0)
1175                 fp->ipq_nfrags--;
1176         m_freem(m);
1177         return (0);
1178
1179 #undef GETIP
1180 }
1181
1182 /*
1183  * Free a fragment reassembly header and all
1184  * associated datagrams.
1185  */
1186 static void
1187 ip_freef(fp)
1188         struct ipq *fp;
1189 {
1190         register struct mbuf *q;
1191
1192         while (fp->ipq_frags) {
1193                 q = fp->ipq_frags;
1194                 fp->ipq_frags = q->m_nextpkt;
1195                 m_freem(q);
1196         }
1197         remque(fp);
1198         (void) m_free(dtom(fp));
1199         nipq--;
1200 }
1201
1202 /*
1203  * IP timer processing;
1204  * if a timer expires on a reassembly
1205  * queue, discard it.
1206  */
1207 void
1208 ip_slowtimo()
1209 {
1210         register struct ipq *fp;
1211         int s = splnet();
1212         int i;
1213
1214         for (i = 0; i < IPREASS_NHASH; i++) {
1215                 fp = ipq[i].next;
1216                 if (fp == 0)
1217                         continue;
1218                 while (fp != &ipq[i]) {
1219                         --fp->ipq_ttl;
1220                         fp = fp->next;
1221                         if (fp->prev->ipq_ttl == 0) {
1222                                 ipstat.ips_fragtimeout += fp->prev->ipq_nfrags;
1223                                 ip_freef(fp->prev);
1224                         }
1225                 }
1226         }
1227         /*
1228          * If we are over the maximum number of fragments
1229          * (due to the limit being lowered), drain off
1230          * enough to get down to the new limit.
1231          */
1232         if (maxnipq >= 0 && nipq > maxnipq) {
1233                 for (i = 0; i < IPREASS_NHASH; i++) {
1234                         while (nipq > maxnipq &&
1235                                 (ipq[i].next != &ipq[i])) {
1236                                 ipstat.ips_fragdropped +=
1237                                     ipq[i].next->ipq_nfrags;
1238                                 ip_freef(ipq[i].next);
1239                         }
1240                 }
1241         }
1242         ipflow_slowtimo();
1243         splx(s);
1244 }
1245
1246 /*
1247  * Drain off all datagram fragments.
1248  */
1249 void
1250 ip_drain()
1251 {
1252         int     i;
1253
1254         for (i = 0; i < IPREASS_NHASH; i++) {
1255                 while (ipq[i].next != &ipq[i]) {
1256                         ipstat.ips_fragdropped += ipq[i].next->ipq_nfrags;
1257                         ip_freef(ipq[i].next);
1258                 }
1259         }
1260         in_rtqdrain();
1261 }
1262
1263 /*
1264  * Do option processing on a datagram,
1265  * possibly discarding it if bad options are encountered,
1266  * or forwarding it if source-routed.
1267  * The pass argument is used when operating in the IPSTEALTH
1268  * mode to tell what options to process:
1269  * [LS]SRR (pass 0) or the others (pass 1).
1270  * The reason for as many as two passes is that when doing IPSTEALTH,
1271  * non-routing options should be processed only if the packet is for us.
1272  * Returns 1 if packet has been forwarded/freed,
1273  * 0 if the packet should be processed further.
1274  */
1275 static int
1276 ip_dooptions(struct mbuf *m, int pass, struct sockaddr_in *next_hop)
1277 {
1278         struct ip *ip = mtod(m, struct ip *);
1279         u_char *cp;
1280         struct in_ifaddr *ia;
1281         int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1282         struct in_addr *sin, dst;
1283         n_time ntime;
1284
1285         dst = ip->ip_dst;
1286         cp = (u_char *)(ip + 1);
1287         cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
1288         for (; cnt > 0; cnt -= optlen, cp += optlen) {
1289                 opt = cp[IPOPT_OPTVAL];
1290                 if (opt == IPOPT_EOL)
1291                         break;
1292                 if (opt == IPOPT_NOP)
1293                         optlen = 1;
1294                 else {
1295                         if (cnt < IPOPT_OLEN + sizeof(*cp)) {
1296                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1297                                 goto bad;
1298                         }
1299                         optlen = cp[IPOPT_OLEN];
1300                         if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
1301                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1302                                 goto bad;
1303                         }
1304                 }
1305                 switch (opt) {
1306
1307                 default:
1308                         break;
1309
1310                 /*
1311                  * Source routing with record.
1312                  * Find interface with current destination address.
1313                  * If none on this machine then drop if strictly routed,
1314                  * or do nothing if loosely routed.
1315                  * Record interface address and bring up next address
1316                  * component.  If strictly routed make sure next
1317                  * address is on directly accessible net.
1318                  */
1319                 case IPOPT_LSRR:
1320                 case IPOPT_SSRR:
1321 #ifdef IPSTEALTH
1322                         if (ipstealth && pass > 0)
1323                                 break;
1324 #endif
1325                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1326                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1327                                 goto bad;
1328                         }
1329                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1330                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1331                                 goto bad;
1332                         }
1333                         ipaddr.sin_addr = ip->ip_dst;
1334                         ia = (struct in_ifaddr *)
1335                                 ifa_ifwithaddr((struct sockaddr *)&ipaddr);
1336                         if (ia == 0) {
1337                                 if (opt == IPOPT_SSRR) {
1338                                         type = ICMP_UNREACH;
1339                                         code = ICMP_UNREACH_SRCFAIL;
1340                                         goto bad;
1341                                 }
1342                                 if (!ip_dosourceroute)
1343                                         goto nosourcerouting;
1344                                 /*
1345                                  * Loose routing, and not at next destination
1346                                  * yet; nothing to do except forward.
1347                                  */
1348                                 break;
1349                         }
1350                         off--;                  /* 0 origin */
1351                         if (off > optlen - (int)sizeof(struct in_addr)) {
1352                                 /*
1353                                  * End of source route.  Should be for us.
1354                                  */
1355                                 if (!ip_acceptsourceroute)
1356                                         goto nosourcerouting;
1357                                 save_rte(cp, ip->ip_src);
1358                                 break;
1359                         }
1360 #ifdef IPSTEALTH
1361                         if (ipstealth)
1362                                 goto dropit;
1363 #endif
1364                         if (!ip_dosourceroute) {
1365                                 if (ipforwarding) {
1366                                         char buf[16]; /* aaa.bbb.ccc.ddd\0 */
1367                                         /*
1368                                          * Acting as a router, so generate ICMP
1369                                          */
1370 nosourcerouting:
1371                                         strcpy(buf, inet_ntoa(ip->ip_dst));
1372                                         log(LOG_WARNING,
1373                                             "attempted source route from %s to %s\n",
1374                                             inet_ntoa(ip->ip_src), buf);
1375                                         type = ICMP_UNREACH;
1376                                         code = ICMP_UNREACH_SRCFAIL;
1377                                         goto bad;
1378                                 } else {
1379                                         /*
1380                                          * Not acting as a router, so silently drop.
1381                                          */
1382 #ifdef IPSTEALTH
1383 dropit:
1384 #endif
1385                                         ipstat.ips_cantforward++;
1386                                         m_freem(m);
1387                                         return (1);
1388                                 }
1389                         }
1390
1391                         /*
1392                          * locate outgoing interface
1393                          */
1394                         (void)memcpy(&ipaddr.sin_addr, cp + off,
1395                             sizeof(ipaddr.sin_addr));
1396
1397                         if (opt == IPOPT_SSRR) {
1398 #define INA     struct in_ifaddr *
1399 #define SA      struct sockaddr *
1400                             if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
1401                                 ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1402                         } else
1403                                 ia = ip_rtaddr(ipaddr.sin_addr, &ipforward_rt);
1404                         if (ia == 0) {
1405                                 type = ICMP_UNREACH;
1406                                 code = ICMP_UNREACH_SRCFAIL;
1407                                 goto bad;
1408                         }
1409                         ip->ip_dst = ipaddr.sin_addr;
1410                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1411                             sizeof(struct in_addr));
1412                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1413                         /*
1414                          * Let ip_intr's mcast routing check handle mcast pkts
1415                          */
1416                         forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
1417                         break;
1418
1419                 case IPOPT_RR:
1420 #ifdef IPSTEALTH
1421                         if (ipstealth && pass == 0)
1422                                 break;
1423 #endif
1424                         if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1425                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1426                                 goto bad;
1427                         }
1428                         if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1429                                 code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1430                                 goto bad;
1431                         }
1432                         /*
1433                          * If no space remains, ignore.
1434                          */
1435                         off--;                  /* 0 origin */
1436                         if (off > optlen - (int)sizeof(struct in_addr))
1437                                 break;
1438                         (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
1439                             sizeof(ipaddr.sin_addr));
1440                         /*
1441                          * locate outgoing interface; if we're the destination,
1442                          * use the incoming interface (should be same).
1443                          */
1444                         if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
1445                             (ia = ip_rtaddr(ipaddr.sin_addr,
1446                             &ipforward_rt)) == 0) {
1447                                 type = ICMP_UNREACH;
1448                                 code = ICMP_UNREACH_HOST;
1449                                 goto bad;
1450                         }
1451                         (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
1452                             sizeof(struct in_addr));
1453                         cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1454                         break;
1455
1456                 case IPOPT_TS:
1457 #ifdef IPSTEALTH
1458                         if (ipstealth && pass == 0)
1459                                 break;
1460 #endif
1461                         code = cp - (u_char *)ip;
1462                         if (optlen < 4 || optlen > 40) {
1463                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1464                                 goto bad;
1465                         }
1466                         if ((off = cp[IPOPT_OFFSET]) < 5) {
1467                                 code = &cp[IPOPT_OLEN] - (u_char *)ip;
1468                                 goto bad;
1469                         }
1470                         if (off > optlen - (int)sizeof(int32_t)) {
1471                                 cp[IPOPT_OFFSET + 1] += (1 << 4);
1472                                 if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
1473                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1474                                         goto bad;
1475                                 }
1476                                 break;
1477                         }
1478                         off--;                          /* 0 origin */
1479                         sin = (struct in_addr *)(cp + off);
1480                         switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
1481
1482                         case IPOPT_TS_TSONLY:
1483                                 break;
1484
1485                         case IPOPT_TS_TSANDADDR:
1486                                 if (off + sizeof(n_time) +
1487                                     sizeof(struct in_addr) > optlen) {
1488                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1489                                         goto bad;
1490                                 }
1491                                 ipaddr.sin_addr = dst;
1492                                 ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
1493                                                             m->m_pkthdr.rcvif);
1494                                 if (ia == 0)
1495                                         continue;
1496                                 (void)memcpy(sin, &IA_SIN(ia)->sin_addr,
1497                                     sizeof(struct in_addr));
1498                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1499                                 off += sizeof(struct in_addr);
1500                                 break;
1501
1502                         case IPOPT_TS_PRESPEC:
1503                                 if (off + sizeof(n_time) +
1504                                     sizeof(struct in_addr) > optlen) {
1505                                         code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1506                                         goto bad;
1507                                 }
1508                                 (void)memcpy(&ipaddr.sin_addr, sin,
1509                                     sizeof(struct in_addr));
1510                                 if (ifa_ifwithaddr((SA)&ipaddr) == 0)
1511                                         continue;
1512                                 cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1513                                 off += sizeof(struct in_addr);
1514                                 break;
1515
1516                         default:
1517                                 code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
1518                                 goto bad;
1519                         }
1520                         ntime = iptime();
1521                         (void)memcpy(cp + off, &ntime, sizeof(n_time));
1522                         cp[IPOPT_OFFSET] += sizeof(n_time);
1523                 }
1524         }
1525         if (forward && ipforwarding) {
1526                 ip_forward(m, 1, next_hop);
1527                 return (1);
1528         }
1529         return (0);
1530 bad:
1531         icmp_error(m, type, code, 0, 0);
1532         ipstat.ips_badoptions++;
1533         return (1);
1534 }
1535
1536 /*
1537  * Given address of next destination (final or next hop),
1538  * return internet address info of interface to be used to get there.
1539  */
1540 struct in_ifaddr *
1541 ip_rtaddr(dst, rt)
1542         struct in_addr dst;
1543         struct route *rt;
1544 {
1545         register struct sockaddr_in *sin;
1546
1547         sin = (struct sockaddr_in *)&rt->ro_dst;
1548
1549         if (rt->ro_rt == 0 ||
1550             dst.s_addr != sin->sin_addr.s_addr) {
1551                 if (rt->ro_rt) {
1552                         RTFREE(rt->ro_rt);
1553                         rt->ro_rt = 0;
1554                 }
1555                 sin->sin_family = AF_INET;
1556                 sin->sin_len = sizeof(*sin);
1557                 sin->sin_addr = dst;
1558
1559                 rtalloc_ign(rt, RTF_PRCLONING);
1560         }
1561         if (rt->ro_rt == 0)
1562                 return ((struct in_ifaddr *)0);
1563         return (ifatoia(rt->ro_rt->rt_ifa));
1564 }
1565
1566 /*
1567  * Save incoming source route for use in replies,
1568  * to be picked up later by ip_srcroute if the receiver is interested.
1569  */
1570 void
1571 save_rte(option, dst)
1572         u_char *option;
1573         struct in_addr dst;
1574 {
1575         unsigned olen;
1576
1577         olen = option[IPOPT_OLEN];
1578 #ifdef DIAGNOSTIC
1579         if (ipprintfs)
1580                 printf("save_rte: olen %d\n", olen);
1581 #endif
1582         if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
1583                 return;
1584         bcopy(option, ip_srcrt.srcopt, olen);
1585         ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1586         ip_srcrt.dst = dst;
1587 }
1588
1589 /*
1590  * Retrieve incoming source route for use in replies,
1591  * in the same form used by setsockopt.
1592  * The first hop is placed before the options, will be removed later.
1593  */
1594 struct mbuf *
1595 ip_srcroute()
1596 {
1597         register struct in_addr *p, *q;
1598         register struct mbuf *m;
1599
1600         if (ip_nhops == 0)
1601                 return ((struct mbuf *)0);
1602         m = m_get(M_DONTWAIT, MT_HEADER);
1603         if (m == 0)
1604                 return ((struct mbuf *)0);
1605
1606 #define OPTSIZ  (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1607
1608         /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1609         m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
1610             OPTSIZ;
1611 #ifdef DIAGNOSTIC
1612         if (ipprintfs)
1613                 printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1614 #endif
1615
1616         /*
1617          * First save first hop for return route
1618          */
1619         p = &ip_srcrt.route[ip_nhops - 1];
1620         *(mtod(m, struct in_addr *)) = *p--;
1621 #ifdef DIAGNOSTIC
1622         if (ipprintfs)
1623                 printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr));
1624 #endif
1625
1626         /*
1627          * Copy option fields and padding (nop) to mbuf.
1628          */
1629         ip_srcrt.nop = IPOPT_NOP;
1630         ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1631         (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
1632             &ip_srcrt.nop, OPTSIZ);
1633         q = (struct in_addr *)(mtod(m, caddr_t) +
1634             sizeof(struct in_addr) + OPTSIZ);
1635 #undef OPTSIZ
1636         /*
1637          * Record return path as an IP source route,
1638          * reversing the path (pointers are now aligned).
1639          */
1640         while (p >= ip_srcrt.route) {
1641 #ifdef DIAGNOSTIC
1642                 if (ipprintfs)
1643                         printf(" %lx", (u_long)ntohl(q->s_addr));
1644 #endif
1645                 *q++ = *p--;
1646         }
1647         /*
1648          * Last hop goes to final destination.
1649          */
1650         *q = ip_srcrt.dst;
1651 #ifdef DIAGNOSTIC
1652         if (ipprintfs)
1653                 printf(" %lx\n", (u_long)ntohl(q->s_addr));
1654 #endif
1655         return (m);
1656 }
1657
1658 /*
1659  * Strip out IP options, at higher
1660  * level protocol in the kernel.
1661  * Second argument is buffer to which options
1662  * will be moved, and return value is their length.
1663  * XXX should be deleted; last arg currently ignored.
1664  */
1665 void
1666 ip_stripoptions(m, mopt)
1667         register struct mbuf *m;
1668         struct mbuf *mopt;
1669 {
1670         register int i;
1671         struct ip *ip = mtod(m, struct ip *);
1672         register caddr_t opts;
1673         int olen;
1674
1675         olen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
1676         opts = (caddr_t)(ip + 1);
1677         i = m->m_len - (sizeof (struct ip) + olen);
1678         bcopy(opts + olen, opts, (unsigned)i);
1679         m->m_len -= olen;
1680         if (m->m_flags & M_PKTHDR)
1681                 m->m_pkthdr.len -= olen;
1682         ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2);
1683 }
1684
1685 u_char inetctlerrmap[PRC_NCMDS] = {
1686         0,              0,              0,              0,
1687         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
1688         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
1689         EMSGSIZE,       EHOSTUNREACH,   0,              0,
1690         0,              0,              0,              0,
1691         ENOPROTOOPT,    ECONNREFUSED
1692 };
1693
1694 /*
1695  * Forward a packet.  If some error occurs return the sender
1696  * an icmp packet.  Note we can't always generate a meaningful
1697  * icmp message because icmp doesn't have a large enough repertoire
1698  * of codes and types.
1699  *
1700  * If not forwarding, just drop the packet.  This could be confusing
1701  * if ipforwarding was zero but some routing protocol was advancing
1702  * us as a gateway to somewhere.  However, we must let the routing
1703  * protocol deal with that.
1704  *
1705  * The srcrt parameter indicates whether the packet is being forwarded
1706  * via a source route.
1707  */
1708 static void
1709 ip_forward(struct mbuf *m, int srcrt, struct sockaddr_in *next_hop)
1710 {
1711         struct ip *ip = mtod(m, struct ip *);
1712         struct sockaddr_in *sin;
1713         struct rtentry *rt;
1714         int error, type = 0, code = 0;
1715         struct mbuf *mcopy;
1716         n_long dest;
1717         struct in_addr pkt_dst;
1718         struct ifnet *destifp;
1719 #if defined(IPSEC) || defined(FAST_IPSEC)
1720         struct ifnet dummyifp;
1721 #endif
1722
1723         dest = 0;
1724         /*
1725          * Cache the destination address of the packet; this may be
1726          * changed by use of 'ipfw fwd'.
1727          */
1728         pkt_dst = next_hop ? next_hop->sin_addr : ip->ip_dst;
1729
1730 #ifdef DIAGNOSTIC
1731         if (ipprintfs)
1732                 printf("forward: src %lx dst %lx ttl %x\n",
1733                     (u_long)ip->ip_src.s_addr, (u_long)pkt_dst.s_addr,
1734                     ip->ip_ttl);
1735 #endif
1736
1737
1738         if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(pkt_dst) == 0) {
1739                 ipstat.ips_cantforward++;
1740                 m_freem(m);
1741                 return;
1742         }
1743 #ifdef IPSTEALTH
1744         if (!ipstealth) {
1745 #endif
1746                 if (ip->ip_ttl <= IPTTLDEC) {
1747                         icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
1748                             dest, 0);
1749                         return;
1750                 }
1751 #ifdef IPSTEALTH
1752         }
1753 #endif
1754
1755         sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
1756         if ((rt = ipforward_rt.ro_rt) == 0 ||
1757             pkt_dst.s_addr != sin->sin_addr.s_addr) {
1758                 if (ipforward_rt.ro_rt) {
1759                         RTFREE(ipforward_rt.ro_rt);
1760                         ipforward_rt.ro_rt = 0;
1761                 }
1762                 sin->sin_family = AF_INET;
1763                 sin->sin_len = sizeof(*sin);
1764                 sin->sin_addr = pkt_dst;
1765
1766                 rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
1767                 if (ipforward_rt.ro_rt == 0) {
1768                         icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1769                         return;
1770                 }
1771                 rt = ipforward_rt.ro_rt;
1772         }
1773
1774         /*
1775          * Save the IP header and at most 8 bytes of the payload,
1776          * in case we need to generate an ICMP message to the src.
1777          *
1778          * XXX this can be optimized a lot by saving the data in a local
1779          * buffer on the stack (72 bytes at most), and only allocating the
1780          * mbuf if really necessary. The vast majority of the packets
1781          * are forwarded without having to send an ICMP back (either
1782          * because unnecessary, or because rate limited), so we are
1783          * really we are wasting a lot of work here.
1784          *
1785          * We don't use m_copy() because it might return a reference
1786          * to a shared cluster. Both this function and ip_output()
1787          * assume exclusive access to the IP header in `m', so any
1788          * data in a cluster may change before we reach icmp_error().
1789          */
1790         MGET(mcopy, M_DONTWAIT, m->m_type);
1791         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
1792                 /*
1793                  * It's probably ok if the pkthdr dup fails (because
1794                  * the deep copy of the tag chain failed), but for now
1795                  * be conservative and just discard the copy since
1796                  * code below may some day want the tags.
1797                  */
1798                 m_free(mcopy);
1799                 mcopy = NULL;
1800         }
1801         if (mcopy != NULL) {
1802                 mcopy->m_len = imin((IP_VHL_HL(ip->ip_vhl) << 2) + 8,
1803                     (int)ip->ip_len);
1804                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
1805         }
1806
1807 #ifdef IPSTEALTH
1808         if (!ipstealth) {
1809 #endif
1810                 ip->ip_ttl -= IPTTLDEC;
1811 #ifdef IPSTEALTH
1812         }
1813 #endif
1814
1815         /*
1816          * If forwarding packet using same interface that it came in on,
1817          * perhaps should send a redirect to sender to shortcut a hop.
1818          * Only send redirect if source is sending directly to us,
1819          * and if packet was not source routed (or has any options).
1820          * Also, don't send redirect if forwarding using a default route
1821          * or a route modified by a redirect.
1822          */
1823         if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1824             (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1825             satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1826             ipsendredirects && !srcrt && !next_hop) {
1827 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1828                 u_long src = ntohl(ip->ip_src.s_addr);
1829
1830                 if (RTA(rt) &&
1831                     (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
1832                     if (rt->rt_flags & RTF_GATEWAY)
1833                         dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1834                     else
1835                         dest = pkt_dst.s_addr;
1836                     /* Router requirements says to only send host redirects */
1837                     type = ICMP_REDIRECT;
1838                     code = ICMP_REDIRECT_HOST;
1839 #ifdef DIAGNOSTIC
1840                     if (ipprintfs)
1841                         printf("redirect (%d) to %lx\n", code, (u_long)dest);
1842 #endif
1843                 }
1844         }
1845
1846     {
1847         struct m_hdr tag;
1848
1849         if (next_hop) {
1850                 /* Pass IPFORWARD info if available */
1851
1852                 tag.mh_type = MT_TAG;
1853                 tag.mh_flags = PACKET_TAG_IPFORWARD;
1854                 tag.mh_data = (caddr_t)next_hop;
1855                 tag.mh_next = m;
1856                 m = (struct mbuf *)&tag;
1857         }
1858         error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
1859                           IP_FORWARDING, 0, NULL);
1860     }
1861         if (error)
1862                 ipstat.ips_cantforward++;
1863         else {
1864                 ipstat.ips_forward++;
1865                 if (type)
1866                         ipstat.ips_redirectsent++;
1867                 else {
1868                         if (mcopy) {
1869                                 ipflow_create(&ipforward_rt, mcopy);
1870                                 m_freem(mcopy);
1871                         }
1872                         return;
1873                 }
1874         }
1875         if (mcopy == NULL)
1876                 return;
1877         destifp = NULL;
1878
1879         switch (error) {
1880
1881         case 0:                         /* forwarded, but need redirect */
1882                 /* type, code set above */
1883                 break;
1884
1885         case ENETUNREACH:               /* shouldn't happen, checked above */
1886         case EHOSTUNREACH:
1887         case ENETDOWN:
1888         case EHOSTDOWN:
1889         default:
1890                 type = ICMP_UNREACH;
1891                 code = ICMP_UNREACH_HOST;
1892                 break;
1893
1894         case EMSGSIZE:
1895                 type = ICMP_UNREACH;
1896                 code = ICMP_UNREACH_NEEDFRAG;
1897 #ifdef IPSEC
1898                 /*
1899                  * If the packet is routed over IPsec tunnel, tell the
1900                  * originator the tunnel MTU.
1901                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1902                  * XXX quickhack!!!
1903                  */
1904                 if (ipforward_rt.ro_rt) {
1905                         struct secpolicy *sp = NULL;
1906                         int ipsecerror;
1907                         int ipsechdr;
1908                         struct route *ro;
1909
1910                         sp = ipsec4_getpolicybyaddr(mcopy,
1911                                                     IPSEC_DIR_OUTBOUND,
1912                                                     IP_FORWARDING,
1913                                                     &ipsecerror);
1914
1915                         if (sp == NULL)
1916                                 destifp = ipforward_rt.ro_rt->rt_ifp;
1917                         else {
1918                                 /* count IPsec header size */
1919                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1920                                                          IPSEC_DIR_OUTBOUND,
1921                                                          NULL);
1922
1923                                 /*
1924                                  * find the correct route for outer IPv4
1925                                  * header, compute tunnel MTU.
1926                                  *
1927                                  * XXX BUG ALERT
1928                                  * The "dummyifp" code relies upon the fact
1929                                  * that icmp_error() touches only ifp->if_mtu.
1930                                  */
1931                                 /*XXX*/
1932                                 destifp = NULL;
1933                                 if (sp->req != NULL
1934                                  && sp->req->sav != NULL
1935                                  && sp->req->sav->sah != NULL) {
1936                                         ro = &sp->req->sav->sah->sa_route;
1937                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1938                                                 dummyifp.if_mtu =
1939                                                     ro->ro_rt->rt_ifp->if_mtu;
1940                                                 dummyifp.if_mtu -= ipsechdr;
1941                                                 destifp = &dummyifp;
1942                                         }
1943                                 }
1944
1945                                 key_freesp(sp);
1946                         }
1947                 }
1948 #elif FAST_IPSEC
1949                 /*
1950                  * If the packet is routed over IPsec tunnel, tell the
1951                  * originator the tunnel MTU.
1952                  *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1953                  * XXX quickhack!!!
1954                  */
1955                 if (ipforward_rt.ro_rt) {
1956                         struct secpolicy *sp = NULL;
1957                         int ipsecerror;
1958                         int ipsechdr;
1959                         struct route *ro;
1960
1961                         sp = ipsec_getpolicybyaddr(mcopy,
1962                                                    IPSEC_DIR_OUTBOUND,
1963                                                    IP_FORWARDING,
1964                                                    &ipsecerror);
1965
1966                         if (sp == NULL)
1967                                 destifp = ipforward_rt.ro_rt->rt_ifp;
1968                         else {
1969                                 /* count IPsec header size */
1970                                 ipsechdr = ipsec4_hdrsiz(mcopy,
1971                                                          IPSEC_DIR_OUTBOUND,
1972                                                          NULL);
1973
1974                                 /*
1975                                  * find the correct route for outer IPv4
1976                                  * header, compute tunnel MTU.
1977                                  *
1978                                  * XXX BUG ALERT
1979                                  * The "dummyifp" code relies upon the fact
1980                                  * that icmp_error() touches only ifp->if_mtu.
1981                                  */
1982                                 /*XXX*/
1983                                 destifp = NULL;
1984                                 if (sp->req != NULL
1985                                  && sp->req->sav != NULL
1986                                  && sp->req->sav->sah != NULL) {
1987                                         ro = &sp->req->sav->sah->sa_route;
1988                                         if (ro->ro_rt && ro->ro_rt->rt_ifp) {
1989                                                 dummyifp.if_mtu =
1990                                                     ro->ro_rt->rt_ifp->if_mtu;
1991                                                 dummyifp.if_mtu -= ipsechdr;
1992                                                 destifp = &dummyifp;
1993                                         }
1994                                 }
1995
1996                                 KEY_FREESP(&sp);
1997                         }
1998                 }
1999 #else /* !IPSEC && !FAST_IPSEC */
2000                 if (ipforward_rt.ro_rt)
2001                         destifp = ipforward_rt.ro_rt->rt_ifp;
2002 #endif /*IPSEC*/
2003                 ipstat.ips_cantfrag++;
2004                 break;
2005
2006         case ENOBUFS:
2007                 /*
2008                  * A router should not generate ICMP_SOURCEQUENCH as
2009                  * required in RFC1812 Requirements for IP Version 4 Routers.
2010                  * Source quench could be a big problem under DoS attacks,
2011                  * or if the underlying interface is rate-limited.
2012                  * Those who need source quench packets may re-enable them
2013                  * via the net.inet.ip.sendsourcequench sysctl.
2014                  */
2015                 if (ip_sendsourcequench == 0) {
2016                         m_freem(mcopy);
2017                         return;
2018                 } else {
2019                         type = ICMP_SOURCEQUENCH;
2020                         code = 0;
2021                 }
2022                 break;
2023
2024         case EACCES:                    /* ipfw denied packet */
2025                 m_freem(mcopy);
2026                 return;
2027         }
2028         icmp_error(mcopy, type, code, dest, destifp);
2029 }
2030
2031 void
2032 ip_savecontrol(inp, mp, ip, m)
2033         register struct inpcb *inp;
2034         register struct mbuf **mp;
2035         register struct ip *ip;
2036         register struct mbuf *m;
2037 {
2038         if (inp->inp_socket->so_options & SO_TIMESTAMP) {
2039                 struct timeval tv;
2040
2041                 microtime(&tv);
2042                 *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
2043                         SCM_TIMESTAMP, SOL_SOCKET);
2044                 if (*mp)
2045                         mp = &(*mp)->m_next;
2046         }
2047         if (inp->inp_flags & INP_RECVDSTADDR) {
2048                 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
2049                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
2050                 if (*mp)
2051                         mp = &(*mp)->m_next;
2052         }
2053 #ifdef notyet
2054         /* XXX
2055          * Moving these out of udp_input() made them even more broken
2056          * than they already were.
2057          */
2058         /* options were tossed already */
2059         if (inp->inp_flags & INP_RECVOPTS) {
2060                 *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
2061                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
2062                 if (*mp)
2063                         mp = &(*mp)->m_next;
2064         }
2065         /* ip_srcroute doesn't do what we want here, need to fix */
2066         if (inp->inp_flags & INP_RECVRETOPTS) {
2067                 *mp = sbcreatecontrol((caddr_t) ip_srcroute(),
2068                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
2069                 if (*mp)
2070                         mp = &(*mp)->m_next;
2071         }
2072 #endif
2073         if (inp->inp_flags & INP_RECVIF) {
2074                 struct ifnet *ifp;
2075                 struct sdlbuf {
2076                         struct sockaddr_dl sdl;
2077                         u_char  pad[32];
2078                 } sdlbuf;
2079                 struct sockaddr_dl *sdp;
2080                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
2081
2082                 if (((ifp = m->m_pkthdr.rcvif))
2083                 && ( ifp->if_index && (ifp->if_index <= if_index))) {
2084                         sdp = (struct sockaddr_dl *)(ifnet_addrs
2085                                         [ifp->if_index - 1]->ifa_addr);
2086                         /*
2087                          * Change our mind and don't try copy.
2088                          */
2089                         if ((sdp->sdl_family != AF_LINK)
2090                         || (sdp->sdl_len > sizeof(sdlbuf))) {
2091                                 goto makedummy;
2092                         }
2093                         bcopy(sdp, sdl2, sdp->sdl_len);
2094                 } else {
2095 makedummy:
2096                         sdl2->sdl_len
2097                                 = offsetof(struct sockaddr_dl, sdl_data[0]);
2098                         sdl2->sdl_family = AF_LINK;
2099                         sdl2->sdl_index = 0;
2100                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
2101                 }
2102                 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
2103                         IP_RECVIF, IPPROTO_IP);
2104                 if (*mp)
2105                         mp = &(*mp)->m_next;
2106         }
2107 }
2108
2109 /*
2110  * XXX these routines are called from the upper part of the kernel.
2111  *
2112  * They could also be moved to ip_mroute.c, since all the RSVP
2113  *  handling is done there already.
2114  */
2115 int
2116 ip_rsvp_init(struct socket *so)
2117 {
2118         if (so->so_type != SOCK_RAW ||
2119             so->so_proto->pr_protocol != IPPROTO_RSVP)
2120                 return EOPNOTSUPP;
2121
2122         if (ip_rsvpd != NULL)
2123                 return EADDRINUSE;
2124
2125         ip_rsvpd = so;
2126         /*
2127          * This may seem silly, but we need to be sure we don't over-increment
2128          * the RSVP counter, in case something slips up.
2129          */
2130         if (!ip_rsvp_on) {
2131                 ip_rsvp_on = 1;
2132                 rsvp_on++;
2133         }
2134
2135         return 0;
2136 }
2137
2138 int
2139 ip_rsvp_done(void)
2140 {
2141         ip_rsvpd = NULL;
2142         /*
2143          * This may seem silly, but we need to be sure we don't over-decrement
2144          * the RSVP counter, in case something slips up.
2145          */
2146         if (ip_rsvp_on) {
2147                 ip_rsvp_on = 0;
2148                 rsvp_on--;
2149         }
2150         return 0;
2151 }
2152
2153 void
2154 rsvp_input(struct mbuf *m, int off, int proto)  /* XXX must fixup manually */
2155 {
2156         if (rsvp_input_p) { /* call the real one if loaded */
2157                 rsvp_input_p(m, off, proto);
2158                 return;
2159         }
2160
2161         /* Can still get packets with rsvp_on = 0 if there is a local member
2162          * of the group to which the RSVP packet is addressed.  But in this
2163          * case we want to throw the packet away.
2164          */
2165
2166         if (!rsvp_on) {
2167                 m_freem(m);
2168                 return;
2169         }
2170
2171         if (ip_rsvpd != NULL) {
2172                 rip_input(m, off, proto);
2173                 return;
2174         }
2175         /* Drop the packet */
2176         m_freem(m);
2177 }
2178