The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_input.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/10.3/sys/netinet/ip_input.c 295896 2016-02-22 19:17:59Z gnn $");
   34 
   35 #include "opt_bootp.h"
   36 #include "opt_ipfw.h"
   37 #include "opt_ipstealth.h"
   38 #include "opt_ipsec.h"
   39 #include "opt_kdtrace.h"
   40 #include "opt_route.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/mbuf.h>
   45 #include <sys/malloc.h>
   46 #include <sys/domain.h>
   47 #include <sys/protosw.h>
   48 #include <sys/socket.h>
   49 #include <sys/time.h>
   50 #include <sys/kernel.h>
   51 #include <sys/lock.h>
   52 #include <sys/rwlock.h>
   53 #include <sys/sdt.h>
   54 #include <sys/syslog.h>
   55 #include <sys/sysctl.h>
   56 
   57 #include <net/pfil.h>
   58 #include <net/if.h>
   59 #include <net/if_types.h>
   60 #include <net/if_var.h>
   61 #include <net/if_dl.h>
   62 #include <net/route.h>
   63 #include <net/netisr.h>
   64 #include <net/vnet.h>
   65 
   66 #include <netinet/in.h>
   67 #include <netinet/in_kdtrace.h>
   68 #include <netinet/in_systm.h>
   69 #include <netinet/in_var.h>
   70 #include <netinet/ip.h>
   71 #include <netinet/in_pcb.h>
   72 #include <netinet/ip_var.h>
   73 #include <netinet/ip_fw.h>
   74 #include <netinet/ip_icmp.h>
   75 #include <netinet/ip_options.h>
   76 #include <machine/in_cksum.h>
   77 #include <netinet/ip_carp.h>
   78 #ifdef IPSEC
   79 #include <netinet/ip_ipsec.h>
   80 #endif /* IPSEC */
   81 
   82 #include <sys/socketvar.h>
   83 
   84 #include <security/mac/mac_framework.h>
   85 
   86 #ifdef CTASSERT
   87 CTASSERT(sizeof(struct ip) == 20);
   88 #endif
   89 
   90 struct  rwlock in_ifaddr_lock;
   91 RW_SYSINIT(in_ifaddr_lock, &in_ifaddr_lock, "in_ifaddr_lock");
   92 
   93 VNET_DEFINE(int, rsvp_on);
   94 
   95 VNET_DEFINE(int, ipforwarding);
   96 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
   97     &VNET_NAME(ipforwarding), 0,
   98     "Enable IP forwarding between interfaces");
   99 
  100 static VNET_DEFINE(int, ipsendredirects) = 1;   /* XXX */
  101 #define V_ipsendredirects       VNET(ipsendredirects)
  102 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
  103     &VNET_NAME(ipsendredirects), 0,
  104     "Enable sending IP redirects");
  105 
  106 static VNET_DEFINE(int, ip_keepfaith);
  107 #define V_ip_keepfaith          VNET(ip_keepfaith)
  108 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
  109     &VNET_NAME(ip_keepfaith), 0,
  110     "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
  111 
  112 static VNET_DEFINE(int, ip_sendsourcequench);
  113 #define V_ip_sendsourcequench   VNET(ip_sendsourcequench)
  114 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
  115     &VNET_NAME(ip_sendsourcequench), 0,
  116     "Enable the transmission of source quench packets");
  117 
  118 VNET_DEFINE(int, ip_do_randomid);
  119 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW,
  120     &VNET_NAME(ip_do_randomid), 0,
  121     "Assign random ip_id values");
  122 
  123 /*
  124  * XXX - Setting ip_checkinterface mostly implements the receive side of
  125  * the Strong ES model described in RFC 1122, but since the routing table
  126  * and transmit implementation do not implement the Strong ES model,
  127  * setting this to 1 results in an odd hybrid.
  128  *
  129  * XXX - ip_checkinterface currently must be disabled if you use ipnat
  130  * to translate the destination address to another local interface.
  131  *
  132  * XXX - ip_checkinterface must be disabled if you add IP aliases
  133  * to the loopback interface instead of the interface where the
  134  * packets for those addresses are received.
  135  */
  136 static VNET_DEFINE(int, ip_checkinterface);
  137 #define V_ip_checkinterface     VNET(ip_checkinterface)
  138 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
  139     &VNET_NAME(ip_checkinterface), 0,
  140     "Verify packet arrives on correct interface");
  141 
  142 VNET_DEFINE(struct pfil_head, inet_pfil_hook);  /* Packet filter hooks */
  143 
  144 static struct netisr_handler ip_nh = {
  145         .nh_name = "ip",
  146         .nh_handler = ip_input,
  147         .nh_proto = NETISR_IP,
  148         .nh_policy = NETISR_POLICY_FLOW,
  149 };
  150 
  151 extern  struct domain inetdomain;
  152 extern  struct protosw inetsw[];
  153 u_char  ip_protox[IPPROTO_MAX];
  154 VNET_DEFINE(struct in_ifaddrhead, in_ifaddrhead);  /* first inet address */
  155 VNET_DEFINE(struct in_ifaddrhashhead *, in_ifaddrhashtbl); /* inet addr hash table  */
  156 VNET_DEFINE(u_long, in_ifaddrhmask);            /* mask for hash table */
  157 
  158 static VNET_DEFINE(uma_zone_t, ipq_zone);
  159 static VNET_DEFINE(TAILQ_HEAD(ipqhead, ipq), ipq[IPREASS_NHASH]);
  160 static struct mtx ipqlock;
  161 
  162 #define V_ipq_zone              VNET(ipq_zone)
  163 #define V_ipq                   VNET(ipq)
  164 
  165 #define IPQ_LOCK()      mtx_lock(&ipqlock)
  166 #define IPQ_UNLOCK()    mtx_unlock(&ipqlock)
  167 #define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF)
  168 #define IPQ_LOCK_ASSERT()       mtx_assert(&ipqlock, MA_OWNED)
  169 
  170 static void     maxnipq_update(void);
  171 static void     ipq_zone_change(void *);
  172 static void     ip_drain_locked(void);
  173 
  174 static VNET_DEFINE(int, maxnipq);  /* Administrative limit on # reass queues. */
  175 static VNET_DEFINE(int, nipq);                  /* Total # of reass queues */
  176 #define V_maxnipq               VNET(maxnipq)
  177 #define V_nipq                  VNET(nipq)
  178 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_RD,
  179     &VNET_NAME(nipq), 0,
  180     "Current number of IPv4 fragment reassembly queue entries");
  181 
  182 static VNET_DEFINE(int, maxfragsperpacket);
  183 #define V_maxfragsperpacket     VNET(maxfragsperpacket)
  184 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
  185     &VNET_NAME(maxfragsperpacket), 0,
  186     "Maximum number of IPv4 fragments allowed per packet");
  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 VNET_DEFINE(int, ipstealth);
  195 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
  196     &VNET_NAME(ipstealth), 0,
  197     "IP stealth mode, no TTL decrementation on forwarding");
  198 #endif
  199 
  200 static void     ip_freef(struct ipqhead *, struct ipq *);
  201 
  202 /*
  203  * IP statistics are stored in the "array" of counter(9)s.
  204  */
  205 VNET_PCPUSTAT_DEFINE(struct ipstat, ipstat);
  206 VNET_PCPUSTAT_SYSINIT(ipstat);
  207 SYSCTL_VNET_PCPUSTAT(_net_inet_ip, IPCTL_STATS, stats, struct ipstat, ipstat,
  208     "IP statistics (struct ipstat, netinet/ip_var.h)");
  209 
  210 #ifdef VIMAGE
  211 VNET_PCPUSTAT_SYSUNINIT(ipstat);
  212 #endif /* VIMAGE */
  213 
  214 /*
  215  * Kernel module interface for updating ipstat.  The argument is an index
  216  * into ipstat treated as an array.
  217  */
  218 void
  219 kmod_ipstat_inc(int statnum)
  220 {
  221 
  222         counter_u64_add(VNET(ipstat)[statnum], 1);
  223 }
  224 
  225 void
  226 kmod_ipstat_dec(int statnum)
  227 {
  228 
  229         counter_u64_add(VNET(ipstat)[statnum], -1);
  230 }
  231 
  232 static int
  233 sysctl_netinet_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)
  234 {
  235         int error, qlimit;
  236 
  237         netisr_getqlimit(&ip_nh, &qlimit);
  238         error = sysctl_handle_int(oidp, &qlimit, 0, req);
  239         if (error || !req->newptr)
  240                 return (error);
  241         if (qlimit < 1)
  242                 return (EINVAL);
  243         return (netisr_setqlimit(&ip_nh, qlimit));
  244 }
  245 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen,
  246     CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet_intr_queue_maxlen, "I",
  247     "Maximum size of the IP input queue");
  248 
  249 static int
  250 sysctl_netinet_intr_queue_drops(SYSCTL_HANDLER_ARGS)
  251 {
  252         u_int64_t qdrops_long;
  253         int error, qdrops;
  254 
  255         netisr_getqdrops(&ip_nh, &qdrops_long);
  256         qdrops = qdrops_long;
  257         error = sysctl_handle_int(oidp, &qdrops, 0, req);
  258         if (error || !req->newptr)
  259                 return (error);
  260         if (qdrops != 0)
  261                 return (EINVAL);
  262         netisr_clearqdrops(&ip_nh);
  263         return (0);
  264 }
  265 
  266 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops,
  267     CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_netinet_intr_queue_drops, "I",
  268     "Number of packets dropped from the IP input queue");
  269 
  270 /*
  271  * IP initialization: fill in IP protocol switch table.
  272  * All protocols not implemented in kernel go to raw IP protocol handler.
  273  */
  274 void
  275 ip_init(void)
  276 {
  277         struct protosw *pr;
  278         int i;
  279 
  280         V_ip_id = time_second & 0xffff;
  281 
  282         TAILQ_INIT(&V_in_ifaddrhead);
  283         V_in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &V_in_ifaddrhmask);
  284 
  285         /* Initialize IP reassembly queue. */
  286         for (i = 0; i < IPREASS_NHASH; i++)
  287                 TAILQ_INIT(&V_ipq[i]);
  288         V_maxnipq = nmbclusters / 32;
  289         V_maxfragsperpacket = 16;
  290         V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
  291             NULL, UMA_ALIGN_PTR, 0);
  292         maxnipq_update();
  293 
  294         /* Initialize packet filter hooks. */
  295         V_inet_pfil_hook.ph_type = PFIL_TYPE_AF;
  296         V_inet_pfil_hook.ph_af = AF_INET;
  297         if ((i = pfil_head_register(&V_inet_pfil_hook)) != 0)
  298                 printf("%s: WARNING: unable to register pfil hook, "
  299                         "error %d\n", __func__, i);
  300 
  301         /* Skip initialization of globals for non-default instances. */
  302         if (!IS_DEFAULT_VNET(curvnet))
  303                 return;
  304 
  305         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
  306         if (pr == NULL)
  307                 panic("ip_init: PF_INET not found");
  308 
  309         /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */
  310         for (i = 0; i < IPPROTO_MAX; i++)
  311                 ip_protox[i] = pr - inetsw;
  312         /*
  313          * Cycle through IP protocols and put them into the appropriate place
  314          * in ip_protox[].
  315          */
  316         for (pr = inetdomain.dom_protosw;
  317             pr < inetdomain.dom_protoswNPROTOSW; pr++)
  318                 if (pr->pr_domain->dom_family == PF_INET &&
  319                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
  320                         /* Be careful to only index valid IP protocols. */
  321                         if (pr->pr_protocol < IPPROTO_MAX)
  322                                 ip_protox[pr->pr_protocol] = pr - inetsw;
  323                 }
  324 
  325         EVENTHANDLER_REGISTER(nmbclusters_change, ipq_zone_change,
  326                 NULL, EVENTHANDLER_PRI_ANY);
  327 
  328         /* Initialize various other remaining things. */
  329         IPQ_LOCK_INIT();
  330         netisr_register(&ip_nh);
  331 }
  332 
  333 #ifdef VIMAGE
  334 void
  335 ip_destroy(void)
  336 {
  337         int i;
  338 
  339         if ((i = pfil_head_unregister(&V_inet_pfil_hook)) != 0)
  340                 printf("%s: WARNING: unable to unregister pfil hook, "
  341                     "error %d\n", __func__, i);
  342 
  343         /* Cleanup in_ifaddr hash table; should be empty. */
  344         hashdestroy(V_in_ifaddrhashtbl, M_IFADDR, V_in_ifaddrhmask);
  345 
  346         IPQ_LOCK();
  347         ip_drain_locked();
  348         IPQ_UNLOCK();
  349 
  350         uma_zdestroy(V_ipq_zone);
  351 }
  352 #endif
  353 
  354 /*
  355  * Ip input routine.  Checksum and byte swap header.  If fragmented
  356  * try to reassemble.  Process options.  Pass to next level.
  357  */
  358 void
  359 ip_input(struct mbuf *m)
  360 {
  361         struct ip *ip = NULL;
  362         struct in_ifaddr *ia = NULL;
  363         struct ifaddr *ifa;
  364         struct ifnet *ifp;
  365         int    checkif, hlen = 0;
  366         uint16_t sum, ip_len;
  367         int dchg = 0;                           /* dest changed after fw */
  368         struct in_addr odst;                    /* original dst address */
  369 
  370         M_ASSERTPKTHDR(m);
  371 
  372         if (m->m_flags & M_FASTFWD_OURS) {
  373                 m->m_flags &= ~M_FASTFWD_OURS;
  374                 /* Set up some basics that will be used later. */
  375                 ip = mtod(m, struct ip *);
  376                 hlen = ip->ip_hl << 2;
  377                 ip_len = ntohs(ip->ip_len);
  378                 goto ours;
  379         }
  380 
  381         IPSTAT_INC(ips_total);
  382 
  383         if (m->m_pkthdr.len < sizeof(struct ip))
  384                 goto tooshort;
  385 
  386         if (m->m_len < sizeof (struct ip) &&
  387             (m = m_pullup(m, sizeof (struct ip))) == NULL) {
  388                 IPSTAT_INC(ips_toosmall);
  389                 return;
  390         }
  391         ip = mtod(m, struct ip *);
  392 
  393         if (ip->ip_v != IPVERSION) {
  394                 IPSTAT_INC(ips_badvers);
  395                 goto bad;
  396         }
  397 
  398         hlen = ip->ip_hl << 2;
  399         if (hlen < sizeof(struct ip)) { /* minimum header length */
  400                 IPSTAT_INC(ips_badhlen);
  401                 goto bad;
  402         }
  403         if (hlen > m->m_len) {
  404                 if ((m = m_pullup(m, hlen)) == NULL) {
  405                         IPSTAT_INC(ips_badhlen);
  406                         return;
  407                 }
  408                 ip = mtod(m, struct ip *);
  409         }
  410 
  411         IP_PROBE(receive, NULL, NULL, ip, m->m_pkthdr.rcvif, ip, NULL);
  412 
  413         /* 127/8 must not appear on wire - RFC1122 */
  414         ifp = m->m_pkthdr.rcvif;
  415         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
  416             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
  417                 if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
  418                         IPSTAT_INC(ips_badaddr);
  419                         goto bad;
  420                 }
  421         }
  422 
  423         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
  424                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
  425         } else {
  426                 if (hlen == sizeof(struct ip)) {
  427                         sum = in_cksum_hdr(ip);
  428                 } else {
  429                         sum = in_cksum(m, hlen);
  430                 }
  431         }
  432         if (sum) {
  433                 IPSTAT_INC(ips_badsum);
  434                 goto bad;
  435         }
  436 
  437 #ifdef ALTQ
  438         if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
  439                 /* packet is dropped by traffic conditioner */
  440                 return;
  441 #endif
  442 
  443         ip_len = ntohs(ip->ip_len);
  444         if (ip_len < hlen) {
  445                 IPSTAT_INC(ips_badlen);
  446                 goto bad;
  447         }
  448 
  449         /*
  450          * Check that the amount of data in the buffers
  451          * is as at least much as the IP header would have us expect.
  452          * Trim mbufs if longer than we expect.
  453          * Drop packet if shorter than we expect.
  454          */
  455         if (m->m_pkthdr.len < ip_len) {
  456 tooshort:
  457                 IPSTAT_INC(ips_tooshort);
  458                 goto bad;
  459         }
  460         if (m->m_pkthdr.len > ip_len) {
  461                 if (m->m_len == m->m_pkthdr.len) {
  462                         m->m_len = ip_len;
  463                         m->m_pkthdr.len = ip_len;
  464                 } else
  465                         m_adj(m, ip_len - m->m_pkthdr.len);
  466         }
  467 #ifdef IPSEC
  468         /*
  469          * Bypass packet filtering for packets previously handled by IPsec.
  470          */
  471         if (ip_ipsec_filtertunnel(m))
  472                 goto passin;
  473 #endif /* IPSEC */
  474 
  475         /*
  476          * Run through list of hooks for input packets.
  477          *
  478          * NB: Beware of the destination address changing (e.g.
  479          *     by NAT rewriting).  When this happens, tell
  480          *     ip_forward to do the right thing.
  481          */
  482 
  483         /* Jump over all PFIL processing if hooks are not active. */
  484         if (!PFIL_HOOKED(&V_inet_pfil_hook))
  485                 goto passin;
  486 
  487         odst = ip->ip_dst;
  488         if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_IN, NULL) != 0)
  489                 return;
  490         if (m == NULL)                  /* consumed by filter */
  491                 return;
  492 
  493         ip = mtod(m, struct ip *);
  494         dchg = (odst.s_addr != ip->ip_dst.s_addr);
  495         ifp = m->m_pkthdr.rcvif;
  496 
  497         if (m->m_flags & M_FASTFWD_OURS) {
  498                 m->m_flags &= ~M_FASTFWD_OURS;
  499                 goto ours;
  500         }
  501         if (m->m_flags & M_IP_NEXTHOP) {
  502                 dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL);
  503                 if (dchg != 0) {
  504                         /*
  505                          * Directly ship the packet on.  This allows
  506                          * forwarding packets originally destined to us
  507                          * to some other directly connected host.
  508                          */
  509                         ip_forward(m, 1);
  510                         return;
  511                 }
  512         }
  513 passin:
  514 
  515         /*
  516          * Process options and, if not destined for us,
  517          * ship it on.  ip_dooptions returns 1 when an
  518          * error was detected (causing an icmp message
  519          * to be sent and the original packet to be freed).
  520          */
  521         if (hlen > sizeof (struct ip) && ip_dooptions(m, 0))
  522                 return;
  523 
  524         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
  525          * matter if it is destined to another node, or whether it is 
  526          * a multicast one, RSVP wants it! and prevents it from being forwarded
  527          * anywhere else. Also checks if the rsvp daemon is running before
  528          * grabbing the packet.
  529          */
  530         if (V_rsvp_on && ip->ip_p==IPPROTO_RSVP) 
  531                 goto ours;
  532 
  533         /*
  534          * Check our list of addresses, to see if the packet is for us.
  535          * If we don't have any addresses, assume any unicast packet
  536          * we receive might be for us (and let the upper layers deal
  537          * with it).
  538          */
  539         if (TAILQ_EMPTY(&V_in_ifaddrhead) &&
  540             (m->m_flags & (M_MCAST|M_BCAST)) == 0)
  541                 goto ours;
  542 
  543         /*
  544          * Enable a consistency check between the destination address
  545          * and the arrival interface for a unicast packet (the RFC 1122
  546          * strong ES model) if IP forwarding is disabled and the packet
  547          * is not locally generated and the packet is not subject to
  548          * 'ipfw fwd'.
  549          *
  550          * XXX - Checking also should be disabled if the destination
  551          * address is ipnat'ed to a different interface.
  552          *
  553          * XXX - Checking is incompatible with IP aliases added
  554          * to the loopback interface instead of the interface where
  555          * the packets are received.
  556          *
  557          * XXX - This is the case for carp vhost IPs as well so we
  558          * insert a workaround. If the packet got here, we already
  559          * checked with carp_iamatch() and carp_forus().
  560          */
  561         checkif = V_ip_checkinterface && (V_ipforwarding == 0) && 
  562             ifp != NULL && ((ifp->if_flags & IFF_LOOPBACK) == 0) &&
  563             ifp->if_carp == NULL && (dchg == 0);
  564 
  565         /*
  566          * Check for exact addresses in the hash bucket.
  567          */
  568         /* IN_IFADDR_RLOCK(); */
  569         LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
  570                 /*
  571                  * If the address matches, verify that the packet
  572                  * arrived via the correct interface if checking is
  573                  * enabled.
  574                  */
  575                 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr && 
  576                     (!checkif || ia->ia_ifp == ifp)) {
  577                         ifa_ref(&ia->ia_ifa);
  578                         /* IN_IFADDR_RUNLOCK(); */
  579                         goto ours;
  580                 }
  581         }
  582         /* IN_IFADDR_RUNLOCK(); */
  583 
  584         /*
  585          * Check for broadcast addresses.
  586          *
  587          * Only accept broadcast packets that arrive via the matching
  588          * interface.  Reception of forwarded directed broadcasts would
  589          * be handled via ip_forward() and ether_output() with the loopback
  590          * into the stack for SIMPLEX interfaces handled by ether_output().
  591          */
  592         if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
  593                 IF_ADDR_RLOCK(ifp);
  594                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  595                         if (ifa->ifa_addr->sa_family != AF_INET)
  596                                 continue;
  597                         ia = ifatoia(ifa);
  598                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
  599                             ip->ip_dst.s_addr) {
  600                                 ifa_ref(ifa);
  601                                 IF_ADDR_RUNLOCK(ifp);
  602                                 goto ours;
  603                         }
  604 #ifdef BOOTP_COMPAT
  605                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) {
  606                                 ifa_ref(ifa);
  607                                 IF_ADDR_RUNLOCK(ifp);
  608                                 goto ours;
  609                         }
  610 #endif
  611                 }
  612                 IF_ADDR_RUNLOCK(ifp);
  613                 ia = NULL;
  614         }
  615         /* RFC 3927 2.7: Do not forward datagrams for 169.254.0.0/16. */
  616         if (IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) {
  617                 IPSTAT_INC(ips_cantforward);
  618                 m_freem(m);
  619                 return;
  620         }
  621         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
  622                 if (V_ip_mrouter) {
  623                         /*
  624                          * If we are acting as a multicast router, all
  625                          * incoming multicast packets are passed to the
  626                          * kernel-level multicast forwarding function.
  627                          * The packet is returned (relatively) intact; if
  628                          * ip_mforward() returns a non-zero value, the packet
  629                          * must be discarded, else it may be accepted below.
  630                          */
  631                         if (ip_mforward && ip_mforward(ip, ifp, m, 0) != 0) {
  632                                 IPSTAT_INC(ips_cantforward);
  633                                 m_freem(m);
  634                                 return;
  635                         }
  636 
  637                         /*
  638                          * The process-level routing daemon needs to receive
  639                          * all multicast IGMP packets, whether or not this
  640                          * host belongs to their destination groups.
  641                          */
  642                         if (ip->ip_p == IPPROTO_IGMP)
  643                                 goto ours;
  644                         IPSTAT_INC(ips_forward);
  645                 }
  646                 /*
  647                  * Assume the packet is for us, to avoid prematurely taking
  648                  * a lock on the in_multi hash. Protocols must perform
  649                  * their own filtering and update statistics accordingly.
  650                  */
  651                 goto ours;
  652         }
  653         if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
  654                 goto ours;
  655         if (ip->ip_dst.s_addr == INADDR_ANY)
  656                 goto ours;
  657 
  658         /*
  659          * FAITH(Firewall Aided Internet Translator)
  660          */
  661         if (ifp && ifp->if_type == IFT_FAITH) {
  662                 if (V_ip_keepfaith) {
  663                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP) 
  664                                 goto ours;
  665                 }
  666                 m_freem(m);
  667                 return;
  668         }
  669 
  670         /*
  671          * Not for us; forward if possible and desirable.
  672          */
  673         if (V_ipforwarding == 0) {
  674                 IPSTAT_INC(ips_cantforward);
  675                 m_freem(m);
  676         } else {
  677 #ifdef IPSEC
  678                 if (ip_ipsec_fwd(m))
  679                         goto bad;
  680 #endif /* IPSEC */
  681                 ip_forward(m, dchg);
  682         }
  683         return;
  684 
  685 ours:
  686 #ifdef IPSTEALTH
  687         /*
  688          * IPSTEALTH: Process non-routing options only
  689          * if the packet is destined for us.
  690          */
  691         if (V_ipstealth && hlen > sizeof (struct ip) && ip_dooptions(m, 1)) {
  692                 if (ia != NULL)
  693                         ifa_free(&ia->ia_ifa);
  694                 return;
  695         }
  696 #endif /* IPSTEALTH */
  697 
  698         /* Count the packet in the ip address stats */
  699         if (ia != NULL) {
  700                 ia->ia_ifa.if_ipackets++;
  701                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
  702                 ifa_free(&ia->ia_ifa);
  703         }
  704 
  705         /*
  706          * Attempt reassembly; if it succeeds, proceed.
  707          * ip_reass() will return a different mbuf.
  708          */
  709         if (ip->ip_off & htons(IP_MF | IP_OFFMASK)) {
  710                 /* XXXGL: shouldn't we save & set m_flags? */
  711                 m = ip_reass(m);
  712                 if (m == NULL)
  713                         return;
  714                 ip = mtod(m, struct ip *);
  715                 /* Get the header length of the reassembled packet */
  716                 hlen = ip->ip_hl << 2;
  717         }
  718 
  719 #ifdef IPSEC
  720         /*
  721          * enforce IPsec policy checking if we are seeing last header.
  722          * note that we do not visit this with protocols with pcb layer
  723          * code - like udp/tcp/raw ip.
  724          */
  725         if (ip_ipsec_input(m))
  726                 goto bad;
  727 #endif /* IPSEC */
  728 
  729         /*
  730          * Switch out to protocol's input routine.
  731          */
  732         IPSTAT_INC(ips_delivered);
  733 
  734         (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
  735         return;
  736 bad:
  737         m_freem(m);
  738 }
  739 
  740 /*
  741  * After maxnipq has been updated, propagate the change to UMA.  The UMA zone
  742  * max has slightly different semantics than the sysctl, for historical
  743  * reasons.
  744  */
  745 static void
  746 maxnipq_update(void)
  747 {
  748 
  749         /*
  750          * -1 for unlimited allocation.
  751          */
  752         if (V_maxnipq < 0)
  753                 uma_zone_set_max(V_ipq_zone, 0);
  754         /*
  755          * Positive number for specific bound.
  756          */
  757         if (V_maxnipq > 0)
  758                 uma_zone_set_max(V_ipq_zone, V_maxnipq);
  759         /*
  760          * Zero specifies no further fragment queue allocation -- set the
  761          * bound very low, but rely on implementation elsewhere to actually
  762          * prevent allocation and reclaim current queues.
  763          */
  764         if (V_maxnipq == 0)
  765                 uma_zone_set_max(V_ipq_zone, 1);
  766 }
  767 
  768 static void
  769 ipq_zone_change(void *tag)
  770 {
  771 
  772         if (V_maxnipq > 0 && V_maxnipq < (nmbclusters / 32)) {
  773                 V_maxnipq = nmbclusters / 32;
  774                 maxnipq_update();
  775         }
  776 }
  777 
  778 static int
  779 sysctl_maxnipq(SYSCTL_HANDLER_ARGS)
  780 {
  781         int error, i;
  782 
  783         i = V_maxnipq;
  784         error = sysctl_handle_int(oidp, &i, 0, req);
  785         if (error || !req->newptr)
  786                 return (error);
  787 
  788         /*
  789          * XXXRW: Might be a good idea to sanity check the argument and place
  790          * an extreme upper bound.
  791          */
  792         if (i < -1)
  793                 return (EINVAL);
  794         V_maxnipq = i;
  795         maxnipq_update();
  796         return (0);
  797 }
  798 
  799 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLTYPE_INT|CTLFLAG_RW,
  800     NULL, 0, sysctl_maxnipq, "I",
  801     "Maximum number of IPv4 fragment reassembly queue entries");
  802 
  803 #define M_IP_FRAG       M_PROTO9
  804 
  805 /*
  806  * Take incoming datagram fragment and try to reassemble it into
  807  * whole datagram.  If the argument is the first fragment or one
  808  * in between the function will return NULL and store the mbuf
  809  * in the fragment chain.  If the argument is the last fragment
  810  * the packet will be reassembled and the pointer to the new
  811  * mbuf returned for further processing.  Only m_tags attached
  812  * to the first packet/fragment are preserved.
  813  * The IP header is *NOT* adjusted out of iplen.
  814  */
  815 struct mbuf *
  816 ip_reass(struct mbuf *m)
  817 {
  818         struct ip *ip;
  819         struct mbuf *p, *q, *nq, *t;
  820         struct ipq *fp = NULL;
  821         struct ipqhead *head;
  822         int i, hlen, next;
  823         u_int8_t ecn, ecn0;
  824         u_short hash;
  825 
  826         /* If maxnipq or maxfragsperpacket are 0, never accept fragments. */
  827         if (V_maxnipq == 0 || V_maxfragsperpacket == 0) {
  828                 IPSTAT_INC(ips_fragments);
  829                 IPSTAT_INC(ips_fragdropped);
  830                 m_freem(m);
  831                 return (NULL);
  832         }
  833 
  834         ip = mtod(m, struct ip *);
  835         hlen = ip->ip_hl << 2;
  836 
  837         hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
  838         head = &V_ipq[hash];
  839         IPQ_LOCK();
  840 
  841         /*
  842          * Look for queue of fragments
  843          * of this datagram.
  844          */
  845         TAILQ_FOREACH(fp, head, ipq_list)
  846                 if (ip->ip_id == fp->ipq_id &&
  847                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
  848                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
  849 #ifdef MAC
  850                     mac_ipq_match(m, fp) &&
  851 #endif
  852                     ip->ip_p == fp->ipq_p)
  853                         goto found;
  854 
  855         fp = NULL;
  856 
  857         /*
  858          * Attempt to trim the number of allocated fragment queues if it
  859          * exceeds the administrative limit.
  860          */
  861         if ((V_nipq > V_maxnipq) && (V_maxnipq > 0)) {
  862                 /*
  863                  * drop something from the tail of the current queue
  864                  * before proceeding further
  865                  */
  866                 struct ipq *q = TAILQ_LAST(head, ipqhead);
  867                 if (q == NULL) {   /* gak */
  868                         for (i = 0; i < IPREASS_NHASH; i++) {
  869                                 struct ipq *r = TAILQ_LAST(&V_ipq[i], ipqhead);
  870                                 if (r) {
  871                                         IPSTAT_ADD(ips_fragtimeout,
  872                                             r->ipq_nfrags);
  873                                         ip_freef(&V_ipq[i], r);
  874                                         break;
  875                                 }
  876                         }
  877                 } else {
  878                         IPSTAT_ADD(ips_fragtimeout, q->ipq_nfrags);
  879                         ip_freef(head, q);
  880                 }
  881         }
  882 
  883 found:
  884         /*
  885          * Adjust ip_len to not reflect header,
  886          * convert offset of this to bytes.
  887          */
  888         ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
  889         if (ip->ip_off & htons(IP_MF)) {
  890                 /*
  891                  * Make sure that fragments have a data length
  892                  * that's a non-zero multiple of 8 bytes.
  893                  */
  894                 if (ip->ip_len == htons(0) || (ntohs(ip->ip_len) & 0x7) != 0) {
  895                         IPSTAT_INC(ips_toosmall); /* XXX */
  896                         goto dropfrag;
  897                 }
  898                 m->m_flags |= M_IP_FRAG;
  899         } else
  900                 m->m_flags &= ~M_IP_FRAG;
  901         ip->ip_off = htons(ntohs(ip->ip_off) << 3);
  902 
  903         /*
  904          * Attempt reassembly; if it succeeds, proceed.
  905          * ip_reass() will return a different mbuf.
  906          */
  907         IPSTAT_INC(ips_fragments);
  908         m->m_pkthdr.PH_loc.ptr = ip;
  909 
  910         /* Previous ip_reass() started here. */
  911         /*
  912          * Presence of header sizes in mbufs
  913          * would confuse code below.
  914          */
  915         m->m_data += hlen;
  916         m->m_len -= hlen;
  917 
  918         /*
  919          * If first fragment to arrive, create a reassembly queue.
  920          */
  921         if (fp == NULL) {
  922                 fp = uma_zalloc(V_ipq_zone, M_NOWAIT);
  923                 if (fp == NULL)
  924                         goto dropfrag;
  925 #ifdef MAC
  926                 if (mac_ipq_init(fp, M_NOWAIT) != 0) {
  927                         uma_zfree(V_ipq_zone, fp);
  928                         fp = NULL;
  929                         goto dropfrag;
  930                 }
  931                 mac_ipq_create(m, fp);
  932 #endif
  933                 TAILQ_INSERT_HEAD(head, fp, ipq_list);
  934                 V_nipq++;
  935                 fp->ipq_nfrags = 1;
  936                 fp->ipq_ttl = IPFRAGTTL;
  937                 fp->ipq_p = ip->ip_p;
  938                 fp->ipq_id = ip->ip_id;
  939                 fp->ipq_src = ip->ip_src;
  940                 fp->ipq_dst = ip->ip_dst;
  941                 fp->ipq_frags = m;
  942                 m->m_nextpkt = NULL;
  943                 goto done;
  944         } else {
  945                 fp->ipq_nfrags++;
  946 #ifdef MAC
  947                 mac_ipq_update(m, fp);
  948 #endif
  949         }
  950 
  951 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.PH_loc.ptr))
  952 
  953         /*
  954          * Handle ECN by comparing this segment with the first one;
  955          * if CE is set, do not lose CE.
  956          * drop if CE and not-ECT are mixed for the same packet.
  957          */
  958         ecn = ip->ip_tos & IPTOS_ECN_MASK;
  959         ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
  960         if (ecn == IPTOS_ECN_CE) {
  961                 if (ecn0 == IPTOS_ECN_NOTECT)
  962                         goto dropfrag;
  963                 if (ecn0 != IPTOS_ECN_CE)
  964                         GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
  965         }
  966         if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
  967                 goto dropfrag;
  968 
  969         /*
  970          * Find a segment which begins after this one does.
  971          */
  972         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
  973                 if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off))
  974                         break;
  975 
  976         /*
  977          * If there is a preceding segment, it may provide some of
  978          * our data already.  If so, drop the data from the incoming
  979          * segment.  If it provides all of our data, drop us, otherwise
  980          * stick new segment in the proper place.
  981          *
  982          * If some of the data is dropped from the preceding
  983          * segment, then it's checksum is invalidated.
  984          */
  985         if (p) {
  986                 i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) -
  987                     ntohs(ip->ip_off);
  988                 if (i > 0) {
  989                         if (i >= ntohs(ip->ip_len))
  990                                 goto dropfrag;
  991                         m_adj(m, i);
  992                         m->m_pkthdr.csum_flags = 0;
  993                         ip->ip_off = htons(ntohs(ip->ip_off) + i);
  994                         ip->ip_len = htons(ntohs(ip->ip_len) - i);
  995                 }
  996                 m->m_nextpkt = p->m_nextpkt;
  997                 p->m_nextpkt = m;
  998         } else {
  999                 m->m_nextpkt = fp->ipq_frags;
 1000                 fp->ipq_frags = m;
 1001         }
 1002 
 1003         /*
 1004          * While we overlap succeeding segments trim them or,
 1005          * if they are completely covered, dequeue them.
 1006          */
 1007         for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) >
 1008             ntohs(GETIP(q)->ip_off); q = nq) {
 1009                 i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) -
 1010                     ntohs(GETIP(q)->ip_off);
 1011                 if (i < ntohs(GETIP(q)->ip_len)) {
 1012                         GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i);
 1013                         GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i);
 1014                         m_adj(q, i);
 1015                         q->m_pkthdr.csum_flags = 0;
 1016                         break;
 1017                 }
 1018                 nq = q->m_nextpkt;
 1019                 m->m_nextpkt = nq;
 1020                 IPSTAT_INC(ips_fragdropped);
 1021                 fp->ipq_nfrags--;
 1022                 m_freem(q);
 1023         }
 1024 
 1025         /*
 1026          * Check for complete reassembly and perform frag per packet
 1027          * limiting.
 1028          *
 1029          * Frag limiting is performed here so that the nth frag has
 1030          * a chance to complete the packet before we drop the packet.
 1031          * As a result, n+1 frags are actually allowed per packet, but
 1032          * only n will ever be stored. (n = maxfragsperpacket.)
 1033          *
 1034          */
 1035         next = 0;
 1036         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
 1037                 if (ntohs(GETIP(q)->ip_off) != next) {
 1038                         if (fp->ipq_nfrags > V_maxfragsperpacket) {
 1039                                 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
 1040                                 ip_freef(head, fp);
 1041                         }
 1042                         goto done;
 1043                 }
 1044                 next += ntohs(GETIP(q)->ip_len);
 1045         }
 1046         /* Make sure the last packet didn't have the IP_MF flag */
 1047         if (p->m_flags & M_IP_FRAG) {
 1048                 if (fp->ipq_nfrags > V_maxfragsperpacket) {
 1049                         IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
 1050                         ip_freef(head, fp);
 1051                 }
 1052                 goto done;
 1053         }
 1054 
 1055         /*
 1056          * Reassembly is complete.  Make sure the packet is a sane size.
 1057          */
 1058         q = fp->ipq_frags;
 1059         ip = GETIP(q);
 1060         if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
 1061                 IPSTAT_INC(ips_toolong);
 1062                 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
 1063                 ip_freef(head, fp);
 1064                 goto done;
 1065         }
 1066 
 1067         /*
 1068          * Concatenate fragments.
 1069          */
 1070         m = q;
 1071         t = m->m_next;
 1072         m->m_next = NULL;
 1073         m_cat(m, t);
 1074         nq = q->m_nextpkt;
 1075         q->m_nextpkt = NULL;
 1076         for (q = nq; q != NULL; q = nq) {
 1077                 nq = q->m_nextpkt;
 1078                 q->m_nextpkt = NULL;
 1079                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
 1080                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
 1081                 m_cat(m, q);
 1082         }
 1083         /*
 1084          * In order to do checksumming faster we do 'end-around carry' here
 1085          * (and not in for{} loop), though it implies we are not going to
 1086          * reassemble more than 64k fragments.
 1087          */
 1088         while (m->m_pkthdr.csum_data & 0xffff0000)
 1089                 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
 1090                     (m->m_pkthdr.csum_data >> 16);
 1091 #ifdef MAC
 1092         mac_ipq_reassemble(fp, m);
 1093         mac_ipq_destroy(fp);
 1094 #endif
 1095 
 1096         /*
 1097          * Create header for new ip packet by modifying header of first
 1098          * packet;  dequeue and discard fragment reassembly header.
 1099          * Make header visible.
 1100          */
 1101         ip->ip_len = htons((ip->ip_hl << 2) + next);
 1102         ip->ip_src = fp->ipq_src;
 1103         ip->ip_dst = fp->ipq_dst;
 1104         TAILQ_REMOVE(head, fp, ipq_list);
 1105         V_nipq--;
 1106         uma_zfree(V_ipq_zone, fp);
 1107         m->m_len += (ip->ip_hl << 2);
 1108         m->m_data -= (ip->ip_hl << 2);
 1109         /* some debugging cruft by sklower, below, will go away soon */
 1110         if (m->m_flags & M_PKTHDR)      /* XXX this should be done elsewhere */
 1111                 m_fixhdr(m);
 1112         IPSTAT_INC(ips_reassembled);
 1113         IPQ_UNLOCK();
 1114         return (m);
 1115 
 1116 dropfrag:
 1117         IPSTAT_INC(ips_fragdropped);
 1118         if (fp != NULL)
 1119                 fp->ipq_nfrags--;
 1120         m_freem(m);
 1121 done:
 1122         IPQ_UNLOCK();
 1123         return (NULL);
 1124 
 1125 #undef GETIP
 1126 }
 1127 
 1128 /*
 1129  * Free a fragment reassembly header and all
 1130  * associated datagrams.
 1131  */
 1132 static void
 1133 ip_freef(struct ipqhead *fhp, struct ipq *fp)
 1134 {
 1135         struct mbuf *q;
 1136 
 1137         IPQ_LOCK_ASSERT();
 1138 
 1139         while (fp->ipq_frags) {
 1140                 q = fp->ipq_frags;
 1141                 fp->ipq_frags = q->m_nextpkt;
 1142                 m_freem(q);
 1143         }
 1144         TAILQ_REMOVE(fhp, fp, ipq_list);
 1145         uma_zfree(V_ipq_zone, fp);
 1146         V_nipq--;
 1147 }
 1148 
 1149 /*
 1150  * IP timer processing;
 1151  * if a timer expires on a reassembly
 1152  * queue, discard it.
 1153  */
 1154 void
 1155 ip_slowtimo(void)
 1156 {
 1157         VNET_ITERATOR_DECL(vnet_iter);
 1158         struct ipq *fp;
 1159         int i;
 1160 
 1161         VNET_LIST_RLOCK_NOSLEEP();
 1162         IPQ_LOCK();
 1163         VNET_FOREACH(vnet_iter) {
 1164                 CURVNET_SET(vnet_iter);
 1165                 for (i = 0; i < IPREASS_NHASH; i++) {
 1166                         for(fp = TAILQ_FIRST(&V_ipq[i]); fp;) {
 1167                                 struct ipq *fpp;
 1168 
 1169                                 fpp = fp;
 1170                                 fp = TAILQ_NEXT(fp, ipq_list);
 1171                                 if(--fpp->ipq_ttl == 0) {
 1172                                         IPSTAT_ADD(ips_fragtimeout,
 1173                                             fpp->ipq_nfrags);
 1174                                         ip_freef(&V_ipq[i], fpp);
 1175                                 }
 1176                         }
 1177                 }
 1178                 /*
 1179                  * If we are over the maximum number of fragments
 1180                  * (due to the limit being lowered), drain off
 1181                  * enough to get down to the new limit.
 1182                  */
 1183                 if (V_maxnipq >= 0 && V_nipq > V_maxnipq) {
 1184                         for (i = 0; i < IPREASS_NHASH; i++) {
 1185                                 while (V_nipq > V_maxnipq &&
 1186                                     !TAILQ_EMPTY(&V_ipq[i])) {
 1187                                         IPSTAT_ADD(ips_fragdropped,
 1188                                             TAILQ_FIRST(&V_ipq[i])->ipq_nfrags);
 1189                                         ip_freef(&V_ipq[i],
 1190                                             TAILQ_FIRST(&V_ipq[i]));
 1191                                 }
 1192                         }
 1193                 }
 1194                 CURVNET_RESTORE();
 1195         }
 1196         IPQ_UNLOCK();
 1197         VNET_LIST_RUNLOCK_NOSLEEP();
 1198 }
 1199 
 1200 /*
 1201  * Drain off all datagram fragments.
 1202  */
 1203 static void
 1204 ip_drain_locked(void)
 1205 {
 1206         int     i;
 1207 
 1208         IPQ_LOCK_ASSERT();
 1209 
 1210         for (i = 0; i < IPREASS_NHASH; i++) {
 1211                 while(!TAILQ_EMPTY(&V_ipq[i])) {
 1212                         IPSTAT_ADD(ips_fragdropped,
 1213                             TAILQ_FIRST(&V_ipq[i])->ipq_nfrags);
 1214                         ip_freef(&V_ipq[i], TAILQ_FIRST(&V_ipq[i]));
 1215                 }
 1216         }
 1217 }
 1218 
 1219 void
 1220 ip_drain(void)
 1221 {
 1222         VNET_ITERATOR_DECL(vnet_iter);
 1223 
 1224         VNET_LIST_RLOCK_NOSLEEP();
 1225         IPQ_LOCK();
 1226         VNET_FOREACH(vnet_iter) {
 1227                 CURVNET_SET(vnet_iter);
 1228                 ip_drain_locked();
 1229                 CURVNET_RESTORE();
 1230         }
 1231         IPQ_UNLOCK();
 1232         VNET_LIST_RUNLOCK_NOSLEEP();
 1233         in_rtqdrain();
 1234 }
 1235 
 1236 /*
 1237  * The protocol to be inserted into ip_protox[] must be already registered
 1238  * in inetsw[], either statically or through pf_proto_register().
 1239  */
 1240 int
 1241 ipproto_register(short ipproto)
 1242 {
 1243         struct protosw *pr;
 1244 
 1245         /* Sanity checks. */
 1246         if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
 1247                 return (EPROTONOSUPPORT);
 1248 
 1249         /*
 1250          * The protocol slot must not be occupied by another protocol
 1251          * already.  An index pointing to IPPROTO_RAW is unused.
 1252          */
 1253         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 1254         if (pr == NULL)
 1255                 return (EPFNOSUPPORT);
 1256         if (ip_protox[ipproto] != pr - inetsw)  /* IPPROTO_RAW */
 1257                 return (EEXIST);
 1258 
 1259         /* Find the protocol position in inetsw[] and set the index. */
 1260         for (pr = inetdomain.dom_protosw;
 1261              pr < inetdomain.dom_protoswNPROTOSW; pr++) {
 1262                 if (pr->pr_domain->dom_family == PF_INET &&
 1263                     pr->pr_protocol && pr->pr_protocol == ipproto) {
 1264                         ip_protox[pr->pr_protocol] = pr - inetsw;
 1265                         return (0);
 1266                 }
 1267         }
 1268         return (EPROTONOSUPPORT);
 1269 }
 1270 
 1271 int
 1272 ipproto_unregister(short ipproto)
 1273 {
 1274         struct protosw *pr;
 1275 
 1276         /* Sanity checks. */
 1277         if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
 1278                 return (EPROTONOSUPPORT);
 1279 
 1280         /* Check if the protocol was indeed registered. */
 1281         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 1282         if (pr == NULL)
 1283                 return (EPFNOSUPPORT);
 1284         if (ip_protox[ipproto] == pr - inetsw)  /* IPPROTO_RAW */
 1285                 return (ENOENT);
 1286 
 1287         /* Reset the protocol slot to IPPROTO_RAW. */
 1288         ip_protox[ipproto] = pr - inetsw;
 1289         return (0);
 1290 }
 1291 
 1292 /*
 1293  * Given address of next destination (final or next hop), return (referenced)
 1294  * internet address info of interface to be used to get there.
 1295  */
 1296 struct in_ifaddr *
 1297 ip_rtaddr(struct in_addr dst, u_int fibnum)
 1298 {
 1299         struct route sro;
 1300         struct sockaddr_in *sin;
 1301         struct in_ifaddr *ia;
 1302 
 1303         bzero(&sro, sizeof(sro));
 1304         sin = (struct sockaddr_in *)&sro.ro_dst;
 1305         sin->sin_family = AF_INET;
 1306         sin->sin_len = sizeof(*sin);
 1307         sin->sin_addr = dst;
 1308         in_rtalloc_ign(&sro, 0, fibnum);
 1309 
 1310         if (sro.ro_rt == NULL)
 1311                 return (NULL);
 1312 
 1313         ia = ifatoia(sro.ro_rt->rt_ifa);
 1314         ifa_ref(&ia->ia_ifa);
 1315         RTFREE(sro.ro_rt);
 1316         return (ia);
 1317 }
 1318 
 1319 u_char inetctlerrmap[PRC_NCMDS] = {
 1320         0,              0,              0,              0,
 1321         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
 1322         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
 1323         EMSGSIZE,       EHOSTUNREACH,   0,              0,
 1324         0,              0,              EHOSTUNREACH,   0,
 1325         ENOPROTOOPT,    ECONNREFUSED
 1326 };
 1327 
 1328 /*
 1329  * Forward a packet.  If some error occurs return the sender
 1330  * an icmp packet.  Note we can't always generate a meaningful
 1331  * icmp message because icmp doesn't have a large enough repertoire
 1332  * of codes and types.
 1333  *
 1334  * If not forwarding, just drop the packet.  This could be confusing
 1335  * if ipforwarding was zero but some routing protocol was advancing
 1336  * us as a gateway to somewhere.  However, we must let the routing
 1337  * protocol deal with that.
 1338  *
 1339  * The srcrt parameter indicates whether the packet is being forwarded
 1340  * via a source route.
 1341  */
 1342 void
 1343 ip_forward(struct mbuf *m, int srcrt)
 1344 {
 1345         struct ip *ip = mtod(m, struct ip *);
 1346         struct in_ifaddr *ia;
 1347         struct mbuf *mcopy;
 1348         struct sockaddr_in *sin;
 1349         struct in_addr dest;
 1350         struct route ro;
 1351         int error, type = 0, code = 0, mtu = 0;
 1352 
 1353         if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
 1354                 IPSTAT_INC(ips_cantforward);
 1355                 m_freem(m);
 1356                 return;
 1357         }
 1358 #ifdef IPSTEALTH
 1359         if (!V_ipstealth) {
 1360 #endif
 1361                 if (ip->ip_ttl <= IPTTLDEC) {
 1362                         icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
 1363                             0, 0);
 1364                         return;
 1365                 }
 1366 #ifdef IPSTEALTH
 1367         }
 1368 #endif
 1369 
 1370         bzero(&ro, sizeof(ro));
 1371         sin = (struct sockaddr_in *)&ro.ro_dst;
 1372         sin->sin_family = AF_INET;
 1373         sin->sin_len = sizeof(*sin);
 1374         sin->sin_addr = ip->ip_dst;
 1375 #ifdef RADIX_MPATH
 1376         rtalloc_mpath_fib(&ro,
 1377             ntohl(ip->ip_src.s_addr ^ ip->ip_dst.s_addr),
 1378             M_GETFIB(m));
 1379 #else
 1380         in_rtalloc_ign(&ro, 0, M_GETFIB(m));
 1381 #endif
 1382         if (ro.ro_rt != NULL) {
 1383                 ia = ifatoia(ro.ro_rt->rt_ifa);
 1384                 ifa_ref(&ia->ia_ifa);
 1385         } else
 1386                 ia = NULL;
 1387 #ifndef IPSEC
 1388         /*
 1389          * 'ia' may be NULL if there is no route for this destination.
 1390          * In case of IPsec, Don't discard it just yet, but pass it to
 1391          * ip_output in case of outgoing IPsec policy.
 1392          */
 1393         if (!srcrt && ia == NULL) {
 1394                 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
 1395                 RO_RTFREE(&ro);
 1396                 return;
 1397         }
 1398 #endif
 1399 
 1400         /*
 1401          * Save the IP header and at most 8 bytes of the payload,
 1402          * in case we need to generate an ICMP message to the src.
 1403          *
 1404          * XXX this can be optimized a lot by saving the data in a local
 1405          * buffer on the stack (72 bytes at most), and only allocating the
 1406          * mbuf if really necessary. The vast majority of the packets
 1407          * are forwarded without having to send an ICMP back (either
 1408          * because unnecessary, or because rate limited), so we are
 1409          * really we are wasting a lot of work here.
 1410          *
 1411          * We don't use m_copy() because it might return a reference
 1412          * to a shared cluster. Both this function and ip_output()
 1413          * assume exclusive access to the IP header in `m', so any
 1414          * data in a cluster may change before we reach icmp_error().
 1415          */
 1416         mcopy = m_gethdr(M_NOWAIT, m->m_type);
 1417         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_NOWAIT)) {
 1418                 /*
 1419                  * It's probably ok if the pkthdr dup fails (because
 1420                  * the deep copy of the tag chain failed), but for now
 1421                  * be conservative and just discard the copy since
 1422                  * code below may some day want the tags.
 1423                  */
 1424                 m_free(mcopy);
 1425                 mcopy = NULL;
 1426         }
 1427         if (mcopy != NULL) {
 1428                 mcopy->m_len = min(ntohs(ip->ip_len), M_TRAILINGSPACE(mcopy));
 1429                 mcopy->m_pkthdr.len = mcopy->m_len;
 1430                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
 1431         }
 1432 
 1433 #ifdef IPSTEALTH
 1434         if (!V_ipstealth) {
 1435 #endif
 1436                 ip->ip_ttl -= IPTTLDEC;
 1437 #ifdef IPSTEALTH
 1438         }
 1439 #endif
 1440 
 1441         /*
 1442          * If forwarding packet using same interface that it came in on,
 1443          * perhaps should send a redirect to sender to shortcut a hop.
 1444          * Only send redirect if source is sending directly to us,
 1445          * and if packet was not source routed (or has any options).
 1446          * Also, don't send redirect if forwarding using a default route
 1447          * or a route modified by a redirect.
 1448          */
 1449         dest.s_addr = 0;
 1450         if (!srcrt && V_ipsendredirects &&
 1451             ia != NULL && ia->ia_ifp == m->m_pkthdr.rcvif) {
 1452                 struct rtentry *rt;
 1453 
 1454                 rt = ro.ro_rt;
 1455 
 1456                 if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
 1457                     satosin(rt_key(rt))->sin_addr.s_addr != 0) {
 1458 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
 1459                         u_long src = ntohl(ip->ip_src.s_addr);
 1460 
 1461                         if (RTA(rt) &&
 1462                             (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
 1463                                 if (rt->rt_flags & RTF_GATEWAY)
 1464                                         dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr;
 1465                                 else
 1466                                         dest.s_addr = ip->ip_dst.s_addr;
 1467                                 /* Router requirements says to only send host redirects */
 1468                                 type = ICMP_REDIRECT;
 1469                                 code = ICMP_REDIRECT_HOST;
 1470                         }
 1471                 }
 1472         }
 1473 
 1474         error = ip_output(m, NULL, &ro, IP_FORWARDING, NULL, NULL);
 1475 
 1476         if (error == EMSGSIZE && ro.ro_rt)
 1477                 mtu = ro.ro_rt->rt_mtu;
 1478         RO_RTFREE(&ro);
 1479 
 1480         if (error)
 1481                 IPSTAT_INC(ips_cantforward);
 1482         else {
 1483                 IPSTAT_INC(ips_forward);
 1484                 if (type)
 1485                         IPSTAT_INC(ips_redirectsent);
 1486                 else {
 1487                         if (mcopy)
 1488                                 m_freem(mcopy);
 1489                         if (ia != NULL)
 1490                                 ifa_free(&ia->ia_ifa);
 1491                         return;
 1492                 }
 1493         }
 1494         if (mcopy == NULL) {
 1495                 if (ia != NULL)
 1496                         ifa_free(&ia->ia_ifa);
 1497                 return;
 1498         }
 1499 
 1500         switch (error) {
 1501 
 1502         case 0:                         /* forwarded, but need redirect */
 1503                 /* type, code set above */
 1504                 break;
 1505 
 1506         case ENETUNREACH:
 1507         case EHOSTUNREACH:
 1508         case ENETDOWN:
 1509         case EHOSTDOWN:
 1510         default:
 1511                 type = ICMP_UNREACH;
 1512                 code = ICMP_UNREACH_HOST;
 1513                 break;
 1514 
 1515         case EMSGSIZE:
 1516                 type = ICMP_UNREACH;
 1517                 code = ICMP_UNREACH_NEEDFRAG;
 1518 
 1519 #ifdef IPSEC
 1520                 /* 
 1521                  * If IPsec is configured for this path,
 1522                  * override any possibly mtu value set by ip_output.
 1523                  */ 
 1524                 mtu = ip_ipsec_mtu(mcopy, mtu);
 1525 #endif /* IPSEC */
 1526                 /*
 1527                  * If the MTU was set before make sure we are below the
 1528                  * interface MTU.
 1529                  * If the MTU wasn't set before use the interface mtu or
 1530                  * fall back to the next smaller mtu step compared to the
 1531                  * current packet size.
 1532                  */
 1533                 if (mtu != 0) {
 1534                         if (ia != NULL)
 1535                                 mtu = min(mtu, ia->ia_ifp->if_mtu);
 1536                 } else {
 1537                         if (ia != NULL)
 1538                                 mtu = ia->ia_ifp->if_mtu;
 1539                         else
 1540                                 mtu = ip_next_mtu(ntohs(ip->ip_len), 0);
 1541                 }
 1542                 IPSTAT_INC(ips_cantfrag);
 1543                 break;
 1544 
 1545         case ENOBUFS:
 1546                 /*
 1547                  * A router should not generate ICMP_SOURCEQUENCH as
 1548                  * required in RFC1812 Requirements for IP Version 4 Routers.
 1549                  * Source quench could be a big problem under DoS attacks,
 1550                  * or if the underlying interface is rate-limited.
 1551                  * Those who need source quench packets may re-enable them
 1552                  * via the net.inet.ip.sendsourcequench sysctl.
 1553                  */
 1554                 if (V_ip_sendsourcequench == 0) {
 1555                         m_freem(mcopy);
 1556                         if (ia != NULL)
 1557                                 ifa_free(&ia->ia_ifa);
 1558                         return;
 1559                 } else {
 1560                         type = ICMP_SOURCEQUENCH;
 1561                         code = 0;
 1562                 }
 1563                 break;
 1564 
 1565         case EACCES:                    /* ipfw denied packet */
 1566                 m_freem(mcopy);
 1567                 if (ia != NULL)
 1568                         ifa_free(&ia->ia_ifa);
 1569                 return;
 1570         }
 1571         if (ia != NULL)
 1572                 ifa_free(&ia->ia_ifa);
 1573         icmp_error(mcopy, type, code, dest.s_addr, mtu);
 1574 }
 1575 
 1576 void
 1577 ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
 1578     struct mbuf *m)
 1579 {
 1580 
 1581         if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) {
 1582                 struct bintime bt;
 1583 
 1584                 bintime(&bt);
 1585                 if (inp->inp_socket->so_options & SO_BINTIME) {
 1586                         *mp = sbcreatecontrol((caddr_t)&bt, sizeof(bt),
 1587                             SCM_BINTIME, SOL_SOCKET);
 1588                         if (*mp)
 1589                                 mp = &(*mp)->m_next;
 1590                 }
 1591                 if (inp->inp_socket->so_options & SO_TIMESTAMP) {
 1592                         struct timeval tv;
 1593 
 1594                         bintime2timeval(&bt, &tv);
 1595                         *mp = sbcreatecontrol((caddr_t)&tv, sizeof(tv),
 1596                             SCM_TIMESTAMP, SOL_SOCKET);
 1597                         if (*mp)
 1598                                 mp = &(*mp)->m_next;
 1599                 }
 1600         }
 1601         if (inp->inp_flags & INP_RECVDSTADDR) {
 1602                 *mp = sbcreatecontrol((caddr_t)&ip->ip_dst,
 1603                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
 1604                 if (*mp)
 1605                         mp = &(*mp)->m_next;
 1606         }
 1607         if (inp->inp_flags & INP_RECVTTL) {
 1608                 *mp = sbcreatecontrol((caddr_t)&ip->ip_ttl,
 1609                     sizeof(u_char), IP_RECVTTL, IPPROTO_IP);
 1610                 if (*mp)
 1611                         mp = &(*mp)->m_next;
 1612         }
 1613 #ifdef notyet
 1614         /* XXX
 1615          * Moving these out of udp_input() made them even more broken
 1616          * than they already were.
 1617          */
 1618         /* options were tossed already */
 1619         if (inp->inp_flags & INP_RECVOPTS) {
 1620                 *mp = sbcreatecontrol((caddr_t)opts_deleted_above,
 1621                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
 1622                 if (*mp)
 1623                         mp = &(*mp)->m_next;
 1624         }
 1625         /* ip_srcroute doesn't do what we want here, need to fix */
 1626         if (inp->inp_flags & INP_RECVRETOPTS) {
 1627                 *mp = sbcreatecontrol((caddr_t)ip_srcroute(m),
 1628                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
 1629                 if (*mp)
 1630                         mp = &(*mp)->m_next;
 1631         }
 1632 #endif
 1633         if (inp->inp_flags & INP_RECVIF) {
 1634                 struct ifnet *ifp;
 1635                 struct sdlbuf {
 1636                         struct sockaddr_dl sdl;
 1637                         u_char  pad[32];
 1638                 } sdlbuf;
 1639                 struct sockaddr_dl *sdp;
 1640                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
 1641 
 1642                 if ((ifp = m->m_pkthdr.rcvif) &&
 1643                     ifp->if_index && ifp->if_index <= V_if_index) {
 1644                         sdp = (struct sockaddr_dl *)ifp->if_addr->ifa_addr;
 1645                         /*
 1646                          * Change our mind and don't try copy.
 1647                          */
 1648                         if (sdp->sdl_family != AF_LINK ||
 1649                             sdp->sdl_len > sizeof(sdlbuf)) {
 1650                                 goto makedummy;
 1651                         }
 1652                         bcopy(sdp, sdl2, sdp->sdl_len);
 1653                 } else {
 1654 makedummy:      
 1655                         sdl2->sdl_len =
 1656                             offsetof(struct sockaddr_dl, sdl_data[0]);
 1657                         sdl2->sdl_family = AF_LINK;
 1658                         sdl2->sdl_index = 0;
 1659                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
 1660                 }
 1661                 *mp = sbcreatecontrol((caddr_t)sdl2, sdl2->sdl_len,
 1662                     IP_RECVIF, IPPROTO_IP);
 1663                 if (*mp)
 1664                         mp = &(*mp)->m_next;
 1665         }
 1666         if (inp->inp_flags & INP_RECVTOS) {
 1667                 *mp = sbcreatecontrol((caddr_t)&ip->ip_tos,
 1668                     sizeof(u_char), IP_RECVTOS, IPPROTO_IP);
 1669                 if (*mp)
 1670                         mp = &(*mp)->m_next;
 1671         }
 1672 }
 1673 
 1674 /*
 1675  * XXXRW: Multicast routing code in ip_mroute.c is generally MPSAFE, but the
 1676  * ip_rsvp and ip_rsvp_on variables need to be interlocked with rsvp_on
 1677  * locking.  This code remains in ip_input.c as ip_mroute.c is optionally
 1678  * compiled.
 1679  */
 1680 static VNET_DEFINE(int, ip_rsvp_on);
 1681 VNET_DEFINE(struct socket *, ip_rsvpd);
 1682 
 1683 #define V_ip_rsvp_on            VNET(ip_rsvp_on)
 1684 
 1685 int
 1686 ip_rsvp_init(struct socket *so)
 1687 {
 1688 
 1689         if (so->so_type != SOCK_RAW ||
 1690             so->so_proto->pr_protocol != IPPROTO_RSVP)
 1691                 return EOPNOTSUPP;
 1692 
 1693         if (V_ip_rsvpd != NULL)
 1694                 return EADDRINUSE;
 1695 
 1696         V_ip_rsvpd = so;
 1697         /*
 1698          * This may seem silly, but we need to be sure we don't over-increment
 1699          * the RSVP counter, in case something slips up.
 1700          */
 1701         if (!V_ip_rsvp_on) {
 1702                 V_ip_rsvp_on = 1;
 1703                 V_rsvp_on++;
 1704         }
 1705 
 1706         return 0;
 1707 }
 1708 
 1709 int
 1710 ip_rsvp_done(void)
 1711 {
 1712 
 1713         V_ip_rsvpd = NULL;
 1714         /*
 1715          * This may seem silly, but we need to be sure we don't over-decrement
 1716          * the RSVP counter, in case something slips up.
 1717          */
 1718         if (V_ip_rsvp_on) {
 1719                 V_ip_rsvp_on = 0;
 1720                 V_rsvp_on--;
 1721         }
 1722         return 0;
 1723 }
 1724 
 1725 void
 1726 rsvp_input(struct mbuf *m, int off)     /* XXX must fixup manually */
 1727 {
 1728 
 1729         if (rsvp_input_p) { /* call the real one if loaded */
 1730                 rsvp_input_p(m, off);
 1731                 return;
 1732         }
 1733 
 1734         /* Can still get packets with rsvp_on = 0 if there is a local member
 1735          * of the group to which the RSVP packet is addressed.  But in this
 1736          * case we want to throw the packet away.
 1737          */
 1738         
 1739         if (!V_rsvp_on) {
 1740                 m_freem(m);
 1741                 return;
 1742         }
 1743 
 1744         if (V_ip_rsvpd != NULL) { 
 1745                 rip_input(m, off);
 1746                 return;
 1747         }
 1748         /* Drop the packet */
 1749         m_freem(m);
 1750 }

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