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("$FreeBSD$");
   34 
   35 #include "opt_bootp.h"
   36 #include "opt_ipfw.h"
   37 #include "opt_ipstealth.h"
   38 #include "opt_ipsec.h"
   39 #include "opt_route.h"
   40 
   41 #include <sys/param.h>
   42 #include <sys/systm.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/malloc.h>
   45 #include <sys/domain.h>
   46 #include <sys/protosw.h>
   47 #include <sys/socket.h>
   48 #include <sys/time.h>
   49 #include <sys/kernel.h>
   50 #include <sys/lock.h>
   51 #include <sys/rwlock.h>
   52 #include <sys/syslog.h>
   53 #include <sys/sysctl.h>
   54 
   55 #include <net/pfil.h>
   56 #include <net/if.h>
   57 #include <net/if_types.h>
   58 #include <net/if_var.h>
   59 #include <net/if_dl.h>
   60 #include <net/route.h>
   61 #include <net/netisr.h>
   62 #include <net/vnet.h>
   63 #include <net/flowtable.h>
   64 
   65 #include <netinet/in.h>
   66 #include <netinet/in_systm.h>
   67 #include <netinet/in_var.h>
   68 #include <netinet/ip.h>
   69 #include <netinet/in_pcb.h>
   70 #include <netinet/ip_var.h>
   71 #include <netinet/ip_fw.h>
   72 #include <netinet/ip_icmp.h>
   73 #include <netinet/ip_options.h>
   74 #include <machine/in_cksum.h>
   75 #include <netinet/ip_carp.h>
   76 #ifdef IPSEC
   77 #include <netinet/ip_ipsec.h>
   78 #endif /* IPSEC */
   79 
   80 #include <sys/socketvar.h>
   81 
   82 #include <security/mac/mac_framework.h>
   83 
   84 #ifdef CTASSERT
   85 CTASSERT(sizeof(struct ip) == 20);
   86 #endif
   87 
   88 struct  rwlock in_ifaddr_lock;
   89 RW_SYSINIT(in_ifaddr_lock, &in_ifaddr_lock, "in_ifaddr_lock");
   90 
   91 VNET_DEFINE(int, rsvp_on);
   92 
   93 VNET_DEFINE(int, ipforwarding);
   94 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
   95     &VNET_NAME(ipforwarding), 0,
   96     "Enable IP forwarding between interfaces");
   97 
   98 static VNET_DEFINE(int, ipsendredirects) = 1;   /* XXX */
   99 #define V_ipsendredirects       VNET(ipsendredirects)
  100 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
  101     &VNET_NAME(ipsendredirects), 0,
  102     "Enable sending IP redirects");
  103 
  104 static VNET_DEFINE(int, ip_keepfaith);
  105 #define V_ip_keepfaith          VNET(ip_keepfaith)
  106 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
  107     &VNET_NAME(ip_keepfaith), 0,
  108     "Enable packet capture for FAITH IPv4->IPv6 translater daemon");
  109 
  110 static VNET_DEFINE(int, ip_sendsourcequench);
  111 #define V_ip_sendsourcequench   VNET(ip_sendsourcequench)
  112 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
  113     &VNET_NAME(ip_sendsourcequench), 0,
  114     "Enable the transmission of source quench packets");
  115 
  116 VNET_DEFINE(int, ip_do_randomid);
  117 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW,
  118     &VNET_NAME(ip_do_randomid), 0,
  119     "Assign random ip_id values");
  120 
  121 /*
  122  * XXX - Setting ip_checkinterface mostly implements the receive side of
  123  * the Strong ES model described in RFC 1122, but since the routing table
  124  * and transmit implementation do not implement the Strong ES model,
  125  * setting this to 1 results in an odd hybrid.
  126  *
  127  * XXX - ip_checkinterface currently must be disabled if you use ipnat
  128  * to translate the destination address to another local interface.
  129  *
  130  * XXX - ip_checkinterface must be disabled if you add IP aliases
  131  * to the loopback interface instead of the interface where the
  132  * packets for those addresses are received.
  133  */
  134 static VNET_DEFINE(int, ip_checkinterface);
  135 #define V_ip_checkinterface     VNET(ip_checkinterface)
  136 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
  137     &VNET_NAME(ip_checkinterface), 0,
  138     "Verify packet arrives on correct interface");
  139 
  140 VNET_DEFINE(struct pfil_head, inet_pfil_hook);  /* Packet filter hooks */
  141 
  142 static struct netisr_handler ip_nh = {
  143         .nh_name = "ip",
  144         .nh_handler = ip_input,
  145         .nh_proto = NETISR_IP,
  146         .nh_policy = NETISR_POLICY_FLOW,
  147 };
  148 
  149 extern  struct domain inetdomain;
  150 extern  struct protosw inetsw[];
  151 u_char  ip_protox[IPPROTO_MAX];
  152 VNET_DEFINE(struct in_ifaddrhead, in_ifaddrhead);  /* first inet address */
  153 VNET_DEFINE(struct in_ifaddrhashhead *, in_ifaddrhashtbl); /* inet addr hash table  */
  154 VNET_DEFINE(u_long, in_ifaddrhmask);            /* mask for hash table */
  155 
  156 VNET_DEFINE(struct ipstat, ipstat);
  157 SYSCTL_VNET_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
  158     &VNET_NAME(ipstat), ipstat,
  159     "IP statistics (struct ipstat, netinet/ip_var.h)");
  160 
  161 static VNET_DEFINE(uma_zone_t, ipq_zone);
  162 static VNET_DEFINE(TAILQ_HEAD(ipqhead, ipq), ipq[IPREASS_NHASH]);
  163 static struct mtx ipqlock;
  164 
  165 #define V_ipq_zone              VNET(ipq_zone)
  166 #define V_ipq                   VNET(ipq)
  167 
  168 #define IPQ_LOCK()      mtx_lock(&ipqlock)
  169 #define IPQ_UNLOCK()    mtx_unlock(&ipqlock)
  170 #define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF)
  171 #define IPQ_LOCK_ASSERT()       mtx_assert(&ipqlock, MA_OWNED)
  172 
  173 static void     maxnipq_update(void);
  174 static void     ipq_zone_change(void *);
  175 static void     ip_drain_locked(void);
  176 
  177 static VNET_DEFINE(int, maxnipq);  /* Administrative limit on # reass queues. */
  178 static VNET_DEFINE(int, nipq);                  /* Total # of reass queues */
  179 #define V_maxnipq               VNET(maxnipq)
  180 #define V_nipq                  VNET(nipq)
  181 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_RD,
  182     &VNET_NAME(nipq), 0,
  183     "Current number of IPv4 fragment reassembly queue entries");
  184 
  185 static VNET_DEFINE(int, maxfragsperpacket);
  186 #define V_maxfragsperpacket     VNET(maxfragsperpacket)
  187 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
  188     &VNET_NAME(maxfragsperpacket), 0,
  189     "Maximum number of IPv4 fragments allowed per packet");
  190 
  191 #ifdef IPCTL_DEFMTU
  192 SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
  193     &ip_mtu, 0, "Default MTU");
  194 #endif
  195 
  196 #ifdef IPSTEALTH
  197 VNET_DEFINE(int, ipstealth);
  198 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
  199     &VNET_NAME(ipstealth), 0,
  200     "IP stealth mode, no TTL decrementation on forwarding");
  201 #endif
  202 
  203 #ifdef FLOWTABLE
  204 static VNET_DEFINE(int, ip_output_flowtable_size) = 2048;
  205 VNET_DEFINE(struct flowtable *, ip_ft);
  206 #define V_ip_output_flowtable_size      VNET(ip_output_flowtable_size)
  207 
  208 SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, output_flowtable_size, CTLFLAG_RDTUN,
  209     &VNET_NAME(ip_output_flowtable_size), 2048,
  210     "number of entries in the per-cpu output flow caches");
  211 #endif
  212 
  213 static void     ip_freef(struct ipqhead *, struct ipq *);
  214 
  215 /*
  216  * Kernel module interface for updating ipstat.  The argument is an index
  217  * into ipstat treated as an array of u_long.  While this encodes the general
  218  * layout of ipstat into the caller, it doesn't encode its location, so that
  219  * future changes to add, for example, per-CPU stats support won't cause
  220  * binary compatibility problems for kernel modules.
  221  */
  222 void
  223 kmod_ipstat_inc(int statnum)
  224 {
  225 
  226         (*((u_long *)&V_ipstat + statnum))++;
  227 }
  228 
  229 void
  230 kmod_ipstat_dec(int statnum)
  231 {
  232 
  233         (*((u_long *)&V_ipstat + statnum))--;
  234 }
  235 
  236 static int
  237 sysctl_netinet_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)
  238 {
  239         int error, qlimit;
  240 
  241         netisr_getqlimit(&ip_nh, &qlimit);
  242         error = sysctl_handle_int(oidp, &qlimit, 0, req);
  243         if (error || !req->newptr)
  244                 return (error);
  245         if (qlimit < 1)
  246                 return (EINVAL);
  247         return (netisr_setqlimit(&ip_nh, qlimit));
  248 }
  249 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen,
  250     CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet_intr_queue_maxlen, "I",
  251     "Maximum size of the IP input queue");
  252 
  253 static int
  254 sysctl_netinet_intr_queue_drops(SYSCTL_HANDLER_ARGS)
  255 {
  256         u_int64_t qdrops_long;
  257         int error, qdrops;
  258 
  259         netisr_getqdrops(&ip_nh, &qdrops_long);
  260         qdrops = qdrops_long;
  261         error = sysctl_handle_int(oidp, &qdrops, 0, req);
  262         if (error || !req->newptr)
  263                 return (error);
  264         if (qdrops != 0)
  265                 return (EINVAL);
  266         netisr_clearqdrops(&ip_nh);
  267         return (0);
  268 }
  269 
  270 SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops,
  271     CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_netinet_intr_queue_drops, "I",
  272     "Number of packets dropped from the IP input queue");
  273 
  274 /*
  275  * IP initialization: fill in IP protocol switch table.
  276  * All protocols not implemented in kernel go to raw IP protocol handler.
  277  */
  278 void
  279 ip_init(void)
  280 {
  281         struct protosw *pr;
  282         int i;
  283 
  284         V_ip_id = time_second & 0xffff;
  285 
  286         TAILQ_INIT(&V_in_ifaddrhead);
  287         V_in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &V_in_ifaddrhmask);
  288 
  289         /* Initialize IP reassembly queue. */
  290         for (i = 0; i < IPREASS_NHASH; i++)
  291                 TAILQ_INIT(&V_ipq[i]);
  292         V_maxnipq = nmbclusters / 32;
  293         V_maxfragsperpacket = 16;
  294         V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
  295             NULL, UMA_ALIGN_PTR, 0);
  296         maxnipq_update();
  297 
  298         /* Initialize packet filter hooks. */
  299         V_inet_pfil_hook.ph_type = PFIL_TYPE_AF;
  300         V_inet_pfil_hook.ph_af = AF_INET;
  301         if ((i = pfil_head_register(&V_inet_pfil_hook)) != 0)
  302                 printf("%s: WARNING: unable to register pfil hook, "
  303                         "error %d\n", __func__, i);
  304 
  305 #ifdef FLOWTABLE
  306         if (TUNABLE_INT_FETCH("net.inet.ip.output_flowtable_size",
  307                 &V_ip_output_flowtable_size)) {
  308                 if (V_ip_output_flowtable_size < 256)
  309                         V_ip_output_flowtable_size = 256;
  310                 if (!powerof2(V_ip_output_flowtable_size)) {
  311                         printf("flowtable must be power of 2 size\n");
  312                         V_ip_output_flowtable_size = 2048;
  313                 }
  314         } else {
  315                 /*
  316                  * round up to the next power of 2
  317                  */
  318                 V_ip_output_flowtable_size = 1 << fls((1024 + maxusers * 64)-1);
  319         }
  320         V_ip_ft = flowtable_alloc("ipv4", V_ip_output_flowtable_size, FL_PCPU);
  321 #endif
  322 
  323         /* Skip initialization of globals for non-default instances. */
  324         if (!IS_DEFAULT_VNET(curvnet))
  325                 return;
  326 
  327         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
  328         if (pr == NULL)
  329                 panic("ip_init: PF_INET not found");
  330 
  331         /* Initialize the entire ip_protox[] array to IPPROTO_RAW. */
  332         for (i = 0; i < IPPROTO_MAX; i++)
  333                 ip_protox[i] = pr - inetsw;
  334         /*
  335          * Cycle through IP protocols and put them into the appropriate place
  336          * in ip_protox[].
  337          */
  338         for (pr = inetdomain.dom_protosw;
  339             pr < inetdomain.dom_protoswNPROTOSW; pr++)
  340                 if (pr->pr_domain->dom_family == PF_INET &&
  341                     pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
  342                         /* Be careful to only index valid IP protocols. */
  343                         if (pr->pr_protocol < IPPROTO_MAX)
  344                                 ip_protox[pr->pr_protocol] = pr - inetsw;
  345                 }
  346 
  347         EVENTHANDLER_REGISTER(nmbclusters_change, ipq_zone_change,
  348                 NULL, EVENTHANDLER_PRI_ANY);
  349 
  350         /* Initialize various other remaining things. */
  351         IPQ_LOCK_INIT();
  352         netisr_register(&ip_nh);
  353 }
  354 
  355 #ifdef VIMAGE
  356 void
  357 ip_destroy(void)
  358 {
  359 
  360         /* Cleanup in_ifaddr hash table; should be empty. */
  361         hashdestroy(V_in_ifaddrhashtbl, M_IFADDR, V_in_ifaddrhmask);
  362 
  363         IPQ_LOCK();
  364         ip_drain_locked();
  365         IPQ_UNLOCK();
  366 
  367         uma_zdestroy(V_ipq_zone);
  368 }
  369 #endif
  370 
  371 /*
  372  * Ip input routine.  Checksum and byte swap header.  If fragmented
  373  * try to reassemble.  Process options.  Pass to next level.
  374  */
  375 void
  376 ip_input(struct mbuf *m)
  377 {
  378         struct ip *ip = NULL;
  379         struct in_ifaddr *ia = NULL;
  380         struct ifaddr *ifa;
  381         struct ifnet *ifp;
  382         int    checkif, hlen = 0;
  383         u_short sum;
  384         int dchg = 0;                           /* dest changed after fw */
  385         struct in_addr odst;                    /* original dst address */
  386 
  387         M_ASSERTPKTHDR(m);
  388 
  389         if (m->m_flags & M_FASTFWD_OURS) {
  390                 /*
  391                  * Firewall or NAT changed destination to local.
  392                  * We expect ip_len and ip_off to be in host byte order.
  393                  */
  394                 m->m_flags &= ~M_FASTFWD_OURS;
  395                 /* Set up some basics that will be used later. */
  396                 ip = mtod(m, struct ip *);
  397                 hlen = ip->ip_hl << 2;
  398                 goto ours;
  399         }
  400 
  401         IPSTAT_INC(ips_total);
  402 
  403         if (m->m_pkthdr.len < sizeof(struct ip))
  404                 goto tooshort;
  405 
  406         if (m->m_len < sizeof (struct ip) &&
  407             (m = m_pullup(m, sizeof (struct ip))) == NULL) {
  408                 IPSTAT_INC(ips_toosmall);
  409                 return;
  410         }
  411         ip = mtod(m, struct ip *);
  412 
  413         if (ip->ip_v != IPVERSION) {
  414                 IPSTAT_INC(ips_badvers);
  415                 goto bad;
  416         }
  417 
  418         hlen = ip->ip_hl << 2;
  419         if (hlen < sizeof(struct ip)) { /* minimum header length */
  420                 IPSTAT_INC(ips_badhlen);
  421                 goto bad;
  422         }
  423         if (hlen > m->m_len) {
  424                 if ((m = m_pullup(m, hlen)) == NULL) {
  425                         IPSTAT_INC(ips_badhlen);
  426                         return;
  427                 }
  428                 ip = mtod(m, struct ip *);
  429         }
  430 
  431         /* 127/8 must not appear on wire - RFC1122 */
  432         ifp = m->m_pkthdr.rcvif;
  433         if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
  434             (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
  435                 if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
  436                         IPSTAT_INC(ips_badaddr);
  437                         goto bad;
  438                 }
  439         }
  440 
  441         if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
  442                 sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
  443         } else {
  444                 if (hlen == sizeof(struct ip)) {
  445                         sum = in_cksum_hdr(ip);
  446                 } else {
  447                         sum = in_cksum(m, hlen);
  448                 }
  449         }
  450         if (sum) {
  451                 IPSTAT_INC(ips_badsum);
  452                 goto bad;
  453         }
  454 
  455 #ifdef ALTQ
  456         if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
  457                 /* packet is dropped by traffic conditioner */
  458                 return;
  459 #endif
  460 
  461         /*
  462          * Convert fields to host representation.
  463          */
  464         ip->ip_len = ntohs(ip->ip_len);
  465         if (ip->ip_len < hlen) {
  466                 IPSTAT_INC(ips_badlen);
  467                 goto bad;
  468         }
  469         ip->ip_off = ntohs(ip->ip_off);
  470 
  471         /*
  472          * Check that the amount of data in the buffers
  473          * is as at least much as the IP header would have us expect.
  474          * Trim mbufs if longer than we expect.
  475          * Drop packet if shorter than we expect.
  476          */
  477         if (m->m_pkthdr.len < ip->ip_len) {
  478 tooshort:
  479                 IPSTAT_INC(ips_tooshort);
  480                 goto bad;
  481         }
  482         if (m->m_pkthdr.len > ip->ip_len) {
  483                 if (m->m_len == m->m_pkthdr.len) {
  484                         m->m_len = ip->ip_len;
  485                         m->m_pkthdr.len = ip->ip_len;
  486                 } else
  487                         m_adj(m, ip->ip_len - m->m_pkthdr.len);
  488         }
  489 #ifdef IPSEC
  490         /*
  491          * Bypass packet filtering for packets previously handled by IPsec.
  492          */
  493         if (ip_ipsec_filtertunnel(m))
  494                 goto passin;
  495 #endif /* IPSEC */
  496 
  497         /*
  498          * Run through list of hooks for input packets.
  499          *
  500          * NB: Beware of the destination address changing (e.g.
  501          *     by NAT rewriting).  When this happens, tell
  502          *     ip_forward to do the right thing.
  503          */
  504 
  505         /* Jump over all PFIL processing if hooks are not active. */
  506         if (!PFIL_HOOKED(&V_inet_pfil_hook))
  507                 goto passin;
  508 
  509         odst = ip->ip_dst;
  510         if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_IN, NULL) != 0)
  511                 return;
  512         if (m == NULL)                  /* consumed by filter */
  513                 return;
  514 
  515         ip = mtod(m, struct ip *);
  516         dchg = (odst.s_addr != ip->ip_dst.s_addr);
  517         ifp = m->m_pkthdr.rcvif;
  518 
  519         if (m->m_flags & M_FASTFWD_OURS) {
  520                 m->m_flags &= ~M_FASTFWD_OURS;
  521                 goto ours;
  522         }
  523         if (m->m_flags & M_IP_NEXTHOP) {
  524                 dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL);
  525                 if (dchg != 0) {
  526                         /*
  527                          * Directly ship the packet on.  This allows
  528                          * forwarding packets originally destined to us
  529                          * to some other directly connected host.
  530                          */
  531                         ip_forward(m, 1);
  532                         return;
  533                 }
  534         }
  535 passin:
  536         /*
  537          * Process options and, if not destined for us,
  538          * ship it on.  ip_dooptions returns 1 when an
  539          * error was detected (causing an icmp message
  540          * to be sent and the original packet to be freed).
  541          */
  542         if (hlen > sizeof (struct ip) && ip_dooptions(m, 0))
  543                 return;
  544 
  545         /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
  546          * matter if it is destined to another node, or whether it is 
  547          * a multicast one, RSVP wants it! and prevents it from being forwarded
  548          * anywhere else. Also checks if the rsvp daemon is running before
  549          * grabbing the packet.
  550          */
  551         if (V_rsvp_on && ip->ip_p==IPPROTO_RSVP) 
  552                 goto ours;
  553 
  554         /*
  555          * Check our list of addresses, to see if the packet is for us.
  556          * If we don't have any addresses, assume any unicast packet
  557          * we receive might be for us (and let the upper layers deal
  558          * with it).
  559          */
  560         if (TAILQ_EMPTY(&V_in_ifaddrhead) &&
  561             (m->m_flags & (M_MCAST|M_BCAST)) == 0)
  562                 goto ours;
  563 
  564         /*
  565          * Enable a consistency check between the destination address
  566          * and the arrival interface for a unicast packet (the RFC 1122
  567          * strong ES model) if IP forwarding is disabled and the packet
  568          * is not locally generated and the packet is not subject to
  569          * 'ipfw fwd'.
  570          *
  571          * XXX - Checking also should be disabled if the destination
  572          * address is ipnat'ed to a different interface.
  573          *
  574          * XXX - Checking is incompatible with IP aliases added
  575          * to the loopback interface instead of the interface where
  576          * the packets are received.
  577          *
  578          * XXX - This is the case for carp vhost IPs as well so we
  579          * insert a workaround. If the packet got here, we already
  580          * checked with carp_iamatch() and carp_forus().
  581          */
  582         checkif = V_ip_checkinterface && (V_ipforwarding == 0) && 
  583             ifp != NULL && ((ifp->if_flags & IFF_LOOPBACK) == 0) &&
  584             ifp->if_carp == NULL && (dchg == 0);
  585 
  586         /*
  587          * Check for exact addresses in the hash bucket.
  588          */
  589         /* IN_IFADDR_RLOCK(); */
  590         LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
  591                 /*
  592                  * If the address matches, verify that the packet
  593                  * arrived via the correct interface if checking is
  594                  * enabled.
  595                  */
  596                 if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr && 
  597                     (!checkif || ia->ia_ifp == ifp)) {
  598                         ifa_ref(&ia->ia_ifa);
  599                         /* IN_IFADDR_RUNLOCK(); */
  600                         goto ours;
  601                 }
  602         }
  603         /* IN_IFADDR_RUNLOCK(); */
  604 
  605         /*
  606          * Check for broadcast addresses.
  607          *
  608          * Only accept broadcast packets that arrive via the matching
  609          * interface.  Reception of forwarded directed broadcasts would
  610          * be handled via ip_forward() and ether_output() with the loopback
  611          * into the stack for SIMPLEX interfaces handled by ether_output().
  612          */
  613         if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
  614                 IF_ADDR_RLOCK(ifp);
  615                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  616                         if (ifa->ifa_addr->sa_family != AF_INET)
  617                                 continue;
  618                         ia = ifatoia(ifa);
  619                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
  620                             ip->ip_dst.s_addr) {
  621                                 ifa_ref(ifa);
  622                                 IF_ADDR_RUNLOCK(ifp);
  623                                 goto ours;
  624                         }
  625 #ifdef BOOTP_COMPAT
  626                         if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) {
  627                                 ifa_ref(ifa);
  628                                 IF_ADDR_RUNLOCK(ifp);
  629                                 goto ours;
  630                         }
  631 #endif
  632                 }
  633                 IF_ADDR_RUNLOCK(ifp);
  634                 ia = NULL;
  635         }
  636         /* RFC 3927 2.7: Do not forward datagrams for 169.254.0.0/16. */
  637         if (IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) {
  638                 IPSTAT_INC(ips_cantforward);
  639                 m_freem(m);
  640                 return;
  641         }
  642         if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
  643                 if (V_ip_mrouter) {
  644                         /*
  645                          * If we are acting as a multicast router, all
  646                          * incoming multicast packets are passed to the
  647                          * kernel-level multicast forwarding function.
  648                          * The packet is returned (relatively) intact; if
  649                          * ip_mforward() returns a non-zero value, the packet
  650                          * must be discarded, else it may be accepted below.
  651                          */
  652                         if (ip_mforward && ip_mforward(ip, ifp, m, 0) != 0) {
  653                                 IPSTAT_INC(ips_cantforward);
  654                                 m_freem(m);
  655                                 return;
  656                         }
  657 
  658                         /*
  659                          * The process-level routing daemon needs to receive
  660                          * all multicast IGMP packets, whether or not this
  661                          * host belongs to their destination groups.
  662                          */
  663                         if (ip->ip_p == IPPROTO_IGMP)
  664                                 goto ours;
  665                         IPSTAT_INC(ips_forward);
  666                 }
  667                 /*
  668                  * Assume the packet is for us, to avoid prematurely taking
  669                  * a lock on the in_multi hash. Protocols must perform
  670                  * their own filtering and update statistics accordingly.
  671                  */
  672                 goto ours;
  673         }
  674         if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
  675                 goto ours;
  676         if (ip->ip_dst.s_addr == INADDR_ANY)
  677                 goto ours;
  678 
  679         /*
  680          * FAITH(Firewall Aided Internet Translator)
  681          */
  682         if (ifp && ifp->if_type == IFT_FAITH) {
  683                 if (V_ip_keepfaith) {
  684                         if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP) 
  685                                 goto ours;
  686                 }
  687                 m_freem(m);
  688                 return;
  689         }
  690 
  691         /*
  692          * Not for us; forward if possible and desirable.
  693          */
  694         if (V_ipforwarding == 0) {
  695                 IPSTAT_INC(ips_cantforward);
  696                 m_freem(m);
  697         } else {
  698 #ifdef IPSEC
  699                 if (ip_ipsec_fwd(m))
  700                         goto bad;
  701 #endif /* IPSEC */
  702                 ip_forward(m, dchg);
  703         }
  704         return;
  705 
  706 ours:
  707 #ifdef IPSTEALTH
  708         /*
  709          * IPSTEALTH: Process non-routing options only
  710          * if the packet is destined for us.
  711          */
  712         if (V_ipstealth && hlen > sizeof (struct ip) && ip_dooptions(m, 1)) {
  713                 if (ia != NULL)
  714                         ifa_free(&ia->ia_ifa);
  715                 return;
  716         }
  717 #endif /* IPSTEALTH */
  718 
  719         /* Count the packet in the ip address stats */
  720         if (ia != NULL) {
  721                 ia->ia_ifa.if_ipackets++;
  722                 ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
  723                 ifa_free(&ia->ia_ifa);
  724         }
  725 
  726         /*
  727          * Attempt reassembly; if it succeeds, proceed.
  728          * ip_reass() will return a different mbuf.
  729          */
  730         if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
  731                 m = ip_reass(m);
  732                 if (m == NULL)
  733                         return;
  734                 ip = mtod(m, struct ip *);
  735                 /* Get the header length of the reassembled packet */
  736                 hlen = ip->ip_hl << 2;
  737         }
  738 
  739         /*
  740          * Further protocols expect the packet length to be w/o the
  741          * IP header.
  742          */
  743         ip->ip_len -= hlen;
  744 
  745 #ifdef IPSEC
  746         /*
  747          * enforce IPsec policy checking if we are seeing last header.
  748          * note that we do not visit this with protocols with pcb layer
  749          * code - like udp/tcp/raw ip.
  750          */
  751         if (ip_ipsec_input(m))
  752                 goto bad;
  753 #endif /* IPSEC */
  754 
  755         /*
  756          * Switch out to protocol's input routine.
  757          */
  758         IPSTAT_INC(ips_delivered);
  759 
  760         (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
  761         return;
  762 bad:
  763         m_freem(m);
  764 }
  765 
  766 /*
  767  * After maxnipq has been updated, propagate the change to UMA.  The UMA zone
  768  * max has slightly different semantics than the sysctl, for historical
  769  * reasons.
  770  */
  771 static void
  772 maxnipq_update(void)
  773 {
  774 
  775         /*
  776          * -1 for unlimited allocation.
  777          */
  778         if (V_maxnipq < 0)
  779                 uma_zone_set_max(V_ipq_zone, 0);
  780         /*
  781          * Positive number for specific bound.
  782          */
  783         if (V_maxnipq > 0)
  784                 uma_zone_set_max(V_ipq_zone, V_maxnipq);
  785         /*
  786          * Zero specifies no further fragment queue allocation -- set the
  787          * bound very low, but rely on implementation elsewhere to actually
  788          * prevent allocation and reclaim current queues.
  789          */
  790         if (V_maxnipq == 0)
  791                 uma_zone_set_max(V_ipq_zone, 1);
  792 }
  793 
  794 static void
  795 ipq_zone_change(void *tag)
  796 {
  797 
  798         if (V_maxnipq > 0 && V_maxnipq < (nmbclusters / 32)) {
  799                 V_maxnipq = nmbclusters / 32;
  800                 maxnipq_update();
  801         }
  802 }
  803 
  804 static int
  805 sysctl_maxnipq(SYSCTL_HANDLER_ARGS)
  806 {
  807         int error, i;
  808 
  809         i = V_maxnipq;
  810         error = sysctl_handle_int(oidp, &i, 0, req);
  811         if (error || !req->newptr)
  812                 return (error);
  813 
  814         /*
  815          * XXXRW: Might be a good idea to sanity check the argument and place
  816          * an extreme upper bound.
  817          */
  818         if (i < -1)
  819                 return (EINVAL);
  820         V_maxnipq = i;
  821         maxnipq_update();
  822         return (0);
  823 }
  824 
  825 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLTYPE_INT|CTLFLAG_RW,
  826     NULL, 0, sysctl_maxnipq, "I",
  827     "Maximum number of IPv4 fragment reassembly queue entries");
  828 
  829 /*
  830  * Take incoming datagram fragment and try to reassemble it into
  831  * whole datagram.  If the argument is the first fragment or one
  832  * in between the function will return NULL and store the mbuf
  833  * in the fragment chain.  If the argument is the last fragment
  834  * the packet will be reassembled and the pointer to the new
  835  * mbuf returned for further processing.  Only m_tags attached
  836  * to the first packet/fragment are preserved.
  837  * The IP header is *NOT* adjusted out of iplen.
  838  */
  839 struct mbuf *
  840 ip_reass(struct mbuf *m)
  841 {
  842         struct ip *ip;
  843         struct mbuf *p, *q, *nq, *t;
  844         struct ipq *fp = NULL;
  845         struct ipqhead *head;
  846         int i, hlen, next;
  847         u_int8_t ecn, ecn0;
  848         u_short hash;
  849 
  850         /* If maxnipq or maxfragsperpacket are 0, never accept fragments. */
  851         if (V_maxnipq == 0 || V_maxfragsperpacket == 0) {
  852                 IPSTAT_INC(ips_fragments);
  853                 IPSTAT_INC(ips_fragdropped);
  854                 m_freem(m);
  855                 return (NULL);
  856         }
  857 
  858         ip = mtod(m, struct ip *);
  859         hlen = ip->ip_hl << 2;
  860 
  861         hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
  862         head = &V_ipq[hash];
  863         IPQ_LOCK();
  864 
  865         /*
  866          * Look for queue of fragments
  867          * of this datagram.
  868          */
  869         TAILQ_FOREACH(fp, head, ipq_list)
  870                 if (ip->ip_id == fp->ipq_id &&
  871                     ip->ip_src.s_addr == fp->ipq_src.s_addr &&
  872                     ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
  873 #ifdef MAC
  874                     mac_ipq_match(m, fp) &&
  875 #endif
  876                     ip->ip_p == fp->ipq_p)
  877                         goto found;
  878 
  879         fp = NULL;
  880 
  881         /*
  882          * Attempt to trim the number of allocated fragment queues if it
  883          * exceeds the administrative limit.
  884          */
  885         if ((V_nipq > V_maxnipq) && (V_maxnipq > 0)) {
  886                 /*
  887                  * drop something from the tail of the current queue
  888                  * before proceeding further
  889                  */
  890                 struct ipq *q = TAILQ_LAST(head, ipqhead);
  891                 if (q == NULL) {   /* gak */
  892                         for (i = 0; i < IPREASS_NHASH; i++) {
  893                                 struct ipq *r = TAILQ_LAST(&V_ipq[i], ipqhead);
  894                                 if (r) {
  895                                         IPSTAT_ADD(ips_fragtimeout,
  896                                             r->ipq_nfrags);
  897                                         ip_freef(&V_ipq[i], r);
  898                                         break;
  899                                 }
  900                         }
  901                 } else {
  902                         IPSTAT_ADD(ips_fragtimeout, q->ipq_nfrags);
  903                         ip_freef(head, q);
  904                 }
  905         }
  906 
  907 found:
  908         /*
  909          * Adjust ip_len to not reflect header,
  910          * convert offset of this to bytes.
  911          */
  912         ip->ip_len -= hlen;
  913         if (ip->ip_off & IP_MF) {
  914                 /*
  915                  * Make sure that fragments have a data length
  916                  * that's a non-zero multiple of 8 bytes.
  917                  */
  918                 if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
  919                         IPSTAT_INC(ips_toosmall); /* XXX */
  920                         goto dropfrag;
  921                 }
  922                 m->m_flags |= M_FRAG;
  923         } else
  924                 m->m_flags &= ~M_FRAG;
  925         ip->ip_off <<= 3;
  926 
  927 
  928         /*
  929          * Attempt reassembly; if it succeeds, proceed.
  930          * ip_reass() will return a different mbuf.
  931          */
  932         IPSTAT_INC(ips_fragments);
  933         m->m_pkthdr.header = ip;
  934 
  935         /* Previous ip_reass() started here. */
  936         /*
  937          * Presence of header sizes in mbufs
  938          * would confuse code below.
  939          */
  940         m->m_data += hlen;
  941         m->m_len -= hlen;
  942 
  943         /*
  944          * If first fragment to arrive, create a reassembly queue.
  945          */
  946         if (fp == NULL) {
  947                 fp = uma_zalloc(V_ipq_zone, M_NOWAIT);
  948                 if (fp == NULL)
  949                         goto dropfrag;
  950 #ifdef MAC
  951                 if (mac_ipq_init(fp, M_NOWAIT) != 0) {
  952                         uma_zfree(V_ipq_zone, fp);
  953                         fp = NULL;
  954                         goto dropfrag;
  955                 }
  956                 mac_ipq_create(m, fp);
  957 #endif
  958                 TAILQ_INSERT_HEAD(head, fp, ipq_list);
  959                 V_nipq++;
  960                 fp->ipq_nfrags = 1;
  961                 fp->ipq_ttl = IPFRAGTTL;
  962                 fp->ipq_p = ip->ip_p;
  963                 fp->ipq_id = ip->ip_id;
  964                 fp->ipq_src = ip->ip_src;
  965                 fp->ipq_dst = ip->ip_dst;
  966                 fp->ipq_frags = m;
  967                 m->m_nextpkt = NULL;
  968                 goto done;
  969         } else {
  970                 fp->ipq_nfrags++;
  971 #ifdef MAC
  972                 mac_ipq_update(m, fp);
  973 #endif
  974         }
  975 
  976 #define GETIP(m)        ((struct ip*)((m)->m_pkthdr.header))
  977 
  978         /*
  979          * Handle ECN by comparing this segment with the first one;
  980          * if CE is set, do not lose CE.
  981          * drop if CE and not-ECT are mixed for the same packet.
  982          */
  983         ecn = ip->ip_tos & IPTOS_ECN_MASK;
  984         ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
  985         if (ecn == IPTOS_ECN_CE) {
  986                 if (ecn0 == IPTOS_ECN_NOTECT)
  987                         goto dropfrag;
  988                 if (ecn0 != IPTOS_ECN_CE)
  989                         GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
  990         }
  991         if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
  992                 goto dropfrag;
  993 
  994         /*
  995          * Find a segment which begins after this one does.
  996          */
  997         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
  998                 if (GETIP(q)->ip_off > ip->ip_off)
  999                         break;
 1000 
 1001         /*
 1002          * If there is a preceding segment, it may provide some of
 1003          * our data already.  If so, drop the data from the incoming
 1004          * segment.  If it provides all of our data, drop us, otherwise
 1005          * stick new segment in the proper place.
 1006          *
 1007          * If some of the data is dropped from the preceding
 1008          * segment, then it's checksum is invalidated.
 1009          */
 1010         if (p) {
 1011                 i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
 1012                 if (i > 0) {
 1013                         if (i >= ip->ip_len)
 1014                                 goto dropfrag;
 1015                         m_adj(m, i);
 1016                         m->m_pkthdr.csum_flags = 0;
 1017                         ip->ip_off += i;
 1018                         ip->ip_len -= i;
 1019                 }
 1020                 m->m_nextpkt = p->m_nextpkt;
 1021                 p->m_nextpkt = m;
 1022         } else {
 1023                 m->m_nextpkt = fp->ipq_frags;
 1024                 fp->ipq_frags = m;
 1025         }
 1026 
 1027         /*
 1028          * While we overlap succeeding segments trim them or,
 1029          * if they are completely covered, dequeue them.
 1030          */
 1031         for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
 1032              q = nq) {
 1033                 i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off;
 1034                 if (i < GETIP(q)->ip_len) {
 1035                         GETIP(q)->ip_len -= i;
 1036                         GETIP(q)->ip_off += i;
 1037                         m_adj(q, i);
 1038                         q->m_pkthdr.csum_flags = 0;
 1039                         break;
 1040                 }
 1041                 nq = q->m_nextpkt;
 1042                 m->m_nextpkt = nq;
 1043                 IPSTAT_INC(ips_fragdropped);
 1044                 fp->ipq_nfrags--;
 1045                 m_freem(q);
 1046         }
 1047 
 1048         /*
 1049          * Check for complete reassembly and perform frag per packet
 1050          * limiting.
 1051          *
 1052          * Frag limiting is performed here so that the nth frag has
 1053          * a chance to complete the packet before we drop the packet.
 1054          * As a result, n+1 frags are actually allowed per packet, but
 1055          * only n will ever be stored. (n = maxfragsperpacket.)
 1056          *
 1057          */
 1058         next = 0;
 1059         for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
 1060                 if (GETIP(q)->ip_off != next) {
 1061                         if (fp->ipq_nfrags > V_maxfragsperpacket) {
 1062                                 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
 1063                                 ip_freef(head, fp);
 1064                         }
 1065                         goto done;
 1066                 }
 1067                 next += GETIP(q)->ip_len;
 1068         }
 1069         /* Make sure the last packet didn't have the IP_MF flag */
 1070         if (p->m_flags & M_FRAG) {
 1071                 if (fp->ipq_nfrags > V_maxfragsperpacket) {
 1072                         IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
 1073                         ip_freef(head, fp);
 1074                 }
 1075                 goto done;
 1076         }
 1077 
 1078         /*
 1079          * Reassembly is complete.  Make sure the packet is a sane size.
 1080          */
 1081         q = fp->ipq_frags;
 1082         ip = GETIP(q);
 1083         if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
 1084                 IPSTAT_INC(ips_toolong);
 1085                 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
 1086                 ip_freef(head, fp);
 1087                 goto done;
 1088         }
 1089 
 1090         /*
 1091          * Concatenate fragments.
 1092          */
 1093         m = q;
 1094         t = m->m_next;
 1095         m->m_next = NULL;
 1096         m_cat(m, t);
 1097         nq = q->m_nextpkt;
 1098         q->m_nextpkt = NULL;
 1099         for (q = nq; q != NULL; q = nq) {
 1100                 nq = q->m_nextpkt;
 1101                 q->m_nextpkt = NULL;
 1102                 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
 1103                 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
 1104                 m_cat(m, q);
 1105         }
 1106         /*
 1107          * In order to do checksumming faster we do 'end-around carry' here
 1108          * (and not in for{} loop), though it implies we are not going to
 1109          * reassemble more than 64k fragments.
 1110          */
 1111         while (m->m_pkthdr.csum_data & 0xffff0000)
 1112                 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
 1113                     (m->m_pkthdr.csum_data >> 16);
 1114 #ifdef MAC
 1115         mac_ipq_reassemble(fp, m);
 1116         mac_ipq_destroy(fp);
 1117 #endif
 1118 
 1119         /*
 1120          * Create header for new ip packet by modifying header of first
 1121          * packet;  dequeue and discard fragment reassembly header.
 1122          * Make header visible.
 1123          */
 1124         ip->ip_len = (ip->ip_hl << 2) + next;
 1125         ip->ip_src = fp->ipq_src;
 1126         ip->ip_dst = fp->ipq_dst;
 1127         TAILQ_REMOVE(head, fp, ipq_list);
 1128         V_nipq--;
 1129         uma_zfree(V_ipq_zone, fp);
 1130         m->m_len += (ip->ip_hl << 2);
 1131         m->m_data -= (ip->ip_hl << 2);
 1132         /* some debugging cruft by sklower, below, will go away soon */
 1133         if (m->m_flags & M_PKTHDR)      /* XXX this should be done elsewhere */
 1134                 m_fixhdr(m);
 1135         IPSTAT_INC(ips_reassembled);
 1136         IPQ_UNLOCK();
 1137         return (m);
 1138 
 1139 dropfrag:
 1140         IPSTAT_INC(ips_fragdropped);
 1141         if (fp != NULL)
 1142                 fp->ipq_nfrags--;
 1143         m_freem(m);
 1144 done:
 1145         IPQ_UNLOCK();
 1146         return (NULL);
 1147 
 1148 #undef GETIP
 1149 }
 1150 
 1151 /*
 1152  * Free a fragment reassembly header and all
 1153  * associated datagrams.
 1154  */
 1155 static void
 1156 ip_freef(struct ipqhead *fhp, struct ipq *fp)
 1157 {
 1158         struct mbuf *q;
 1159 
 1160         IPQ_LOCK_ASSERT();
 1161 
 1162         while (fp->ipq_frags) {
 1163                 q = fp->ipq_frags;
 1164                 fp->ipq_frags = q->m_nextpkt;
 1165                 m_freem(q);
 1166         }
 1167         TAILQ_REMOVE(fhp, fp, ipq_list);
 1168         uma_zfree(V_ipq_zone, fp);
 1169         V_nipq--;
 1170 }
 1171 
 1172 /*
 1173  * IP timer processing;
 1174  * if a timer expires on a reassembly
 1175  * queue, discard it.
 1176  */
 1177 void
 1178 ip_slowtimo(void)
 1179 {
 1180         VNET_ITERATOR_DECL(vnet_iter);
 1181         struct ipq *fp;
 1182         int i;
 1183 
 1184         VNET_LIST_RLOCK_NOSLEEP();
 1185         IPQ_LOCK();
 1186         VNET_FOREACH(vnet_iter) {
 1187                 CURVNET_SET(vnet_iter);
 1188                 for (i = 0; i < IPREASS_NHASH; i++) {
 1189                         for(fp = TAILQ_FIRST(&V_ipq[i]); fp;) {
 1190                                 struct ipq *fpp;
 1191 
 1192                                 fpp = fp;
 1193                                 fp = TAILQ_NEXT(fp, ipq_list);
 1194                                 if(--fpp->ipq_ttl == 0) {
 1195                                         IPSTAT_ADD(ips_fragtimeout,
 1196                                             fpp->ipq_nfrags);
 1197                                         ip_freef(&V_ipq[i], fpp);
 1198                                 }
 1199                         }
 1200                 }
 1201                 /*
 1202                  * If we are over the maximum number of fragments
 1203                  * (due to the limit being lowered), drain off
 1204                  * enough to get down to the new limit.
 1205                  */
 1206                 if (V_maxnipq >= 0 && V_nipq > V_maxnipq) {
 1207                         for (i = 0; i < IPREASS_NHASH; i++) {
 1208                                 while (V_nipq > V_maxnipq &&
 1209                                     !TAILQ_EMPTY(&V_ipq[i])) {
 1210                                         IPSTAT_ADD(ips_fragdropped,
 1211                                             TAILQ_FIRST(&V_ipq[i])->ipq_nfrags);
 1212                                         ip_freef(&V_ipq[i],
 1213                                             TAILQ_FIRST(&V_ipq[i]));
 1214                                 }
 1215                         }
 1216                 }
 1217                 CURVNET_RESTORE();
 1218         }
 1219         IPQ_UNLOCK();
 1220         VNET_LIST_RUNLOCK_NOSLEEP();
 1221 }
 1222 
 1223 /*
 1224  * Drain off all datagram fragments.
 1225  */
 1226 static void
 1227 ip_drain_locked(void)
 1228 {
 1229         int     i;
 1230 
 1231         IPQ_LOCK_ASSERT();
 1232 
 1233         for (i = 0; i < IPREASS_NHASH; i++) {
 1234                 while(!TAILQ_EMPTY(&V_ipq[i])) {
 1235                         IPSTAT_ADD(ips_fragdropped,
 1236                             TAILQ_FIRST(&V_ipq[i])->ipq_nfrags);
 1237                         ip_freef(&V_ipq[i], TAILQ_FIRST(&V_ipq[i]));
 1238                 }
 1239         }
 1240 }
 1241 
 1242 void
 1243 ip_drain(void)
 1244 {
 1245         VNET_ITERATOR_DECL(vnet_iter);
 1246 
 1247         VNET_LIST_RLOCK_NOSLEEP();
 1248         IPQ_LOCK();
 1249         VNET_FOREACH(vnet_iter) {
 1250                 CURVNET_SET(vnet_iter);
 1251                 ip_drain_locked();
 1252                 CURVNET_RESTORE();
 1253         }
 1254         IPQ_UNLOCK();
 1255         VNET_LIST_RUNLOCK_NOSLEEP();
 1256         in_rtqdrain();
 1257 }
 1258 
 1259 /*
 1260  * The protocol to be inserted into ip_protox[] must be already registered
 1261  * in inetsw[], either statically or through pf_proto_register().
 1262  */
 1263 int
 1264 ipproto_register(short ipproto)
 1265 {
 1266         struct protosw *pr;
 1267 
 1268         /* Sanity checks. */
 1269         if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
 1270                 return (EPROTONOSUPPORT);
 1271 
 1272         /*
 1273          * The protocol slot must not be occupied by another protocol
 1274          * already.  An index pointing to IPPROTO_RAW is unused.
 1275          */
 1276         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 1277         if (pr == NULL)
 1278                 return (EPFNOSUPPORT);
 1279         if (ip_protox[ipproto] != pr - inetsw)  /* IPPROTO_RAW */
 1280                 return (EEXIST);
 1281 
 1282         /* Find the protocol position in inetsw[] and set the index. */
 1283         for (pr = inetdomain.dom_protosw;
 1284              pr < inetdomain.dom_protoswNPROTOSW; pr++) {
 1285                 if (pr->pr_domain->dom_family == PF_INET &&
 1286                     pr->pr_protocol && pr->pr_protocol == ipproto) {
 1287                         ip_protox[pr->pr_protocol] = pr - inetsw;
 1288                         return (0);
 1289                 }
 1290         }
 1291         return (EPROTONOSUPPORT);
 1292 }
 1293 
 1294 int
 1295 ipproto_unregister(short ipproto)
 1296 {
 1297         struct protosw *pr;
 1298 
 1299         /* Sanity checks. */
 1300         if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
 1301                 return (EPROTONOSUPPORT);
 1302 
 1303         /* Check if the protocol was indeed registered. */
 1304         pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
 1305         if (pr == NULL)
 1306                 return (EPFNOSUPPORT);
 1307         if (ip_protox[ipproto] == pr - inetsw)  /* IPPROTO_RAW */
 1308                 return (ENOENT);
 1309 
 1310         /* Reset the protocol slot to IPPROTO_RAW. */
 1311         ip_protox[ipproto] = pr - inetsw;
 1312         return (0);
 1313 }
 1314 
 1315 /*
 1316  * Given address of next destination (final or next hop), return (referenced)
 1317  * internet address info of interface to be used to get there.
 1318  */
 1319 struct in_ifaddr *
 1320 ip_rtaddr(struct in_addr dst, u_int fibnum)
 1321 {
 1322         struct route sro;
 1323         struct sockaddr_in *sin;
 1324         struct in_ifaddr *ia;
 1325 
 1326         bzero(&sro, sizeof(sro));
 1327         sin = (struct sockaddr_in *)&sro.ro_dst;
 1328         sin->sin_family = AF_INET;
 1329         sin->sin_len = sizeof(*sin);
 1330         sin->sin_addr = dst;
 1331         in_rtalloc_ign(&sro, 0, fibnum);
 1332 
 1333         if (sro.ro_rt == NULL)
 1334                 return (NULL);
 1335 
 1336         ia = ifatoia(sro.ro_rt->rt_ifa);
 1337         ifa_ref(&ia->ia_ifa);
 1338         RTFREE(sro.ro_rt);
 1339         return (ia);
 1340 }
 1341 
 1342 u_char inetctlerrmap[PRC_NCMDS] = {
 1343         0,              0,              0,              0,
 1344         0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
 1345         EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
 1346         EMSGSIZE,       EHOSTUNREACH,   0,              0,
 1347         0,              0,              EHOSTUNREACH,   0,
 1348         ENOPROTOOPT,    ECONNREFUSED
 1349 };
 1350 
 1351 /*
 1352  * Forward a packet.  If some error occurs return the sender
 1353  * an icmp packet.  Note we can't always generate a meaningful
 1354  * icmp message because icmp doesn't have a large enough repertoire
 1355  * of codes and types.
 1356  *
 1357  * If not forwarding, just drop the packet.  This could be confusing
 1358  * if ipforwarding was zero but some routing protocol was advancing
 1359  * us as a gateway to somewhere.  However, we must let the routing
 1360  * protocol deal with that.
 1361  *
 1362  * The srcrt parameter indicates whether the packet is being forwarded
 1363  * via a source route.
 1364  */
 1365 void
 1366 ip_forward(struct mbuf *m, int srcrt)
 1367 {
 1368         struct ip *ip = mtod(m, struct ip *);
 1369         struct in_ifaddr *ia;
 1370         struct mbuf *mcopy;
 1371         struct in_addr dest;
 1372         struct route ro;
 1373         int error, type = 0, code = 0, mtu = 0;
 1374 
 1375         if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
 1376                 IPSTAT_INC(ips_cantforward);
 1377                 m_freem(m);
 1378                 return;
 1379         }
 1380 #ifdef IPSTEALTH
 1381         if (!V_ipstealth) {
 1382 #endif
 1383                 if (ip->ip_ttl <= IPTTLDEC) {
 1384                         icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
 1385                             0, 0);
 1386                         return;
 1387                 }
 1388 #ifdef IPSTEALTH
 1389         }
 1390 #endif
 1391 
 1392         ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
 1393 #ifndef IPSEC
 1394         /*
 1395          * 'ia' may be NULL if there is no route for this destination.
 1396          * In case of IPsec, Don't discard it just yet, but pass it to
 1397          * ip_output in case of outgoing IPsec policy.
 1398          */
 1399         if (!srcrt && ia == NULL) {
 1400                 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
 1401                 return;
 1402         }
 1403 #endif
 1404 
 1405         /*
 1406          * Save the IP header and at most 8 bytes of the payload,
 1407          * in case we need to generate an ICMP message to the src.
 1408          *
 1409          * XXX this can be optimized a lot by saving the data in a local
 1410          * buffer on the stack (72 bytes at most), and only allocating the
 1411          * mbuf if really necessary. The vast majority of the packets
 1412          * are forwarded without having to send an ICMP back (either
 1413          * because unnecessary, or because rate limited), so we are
 1414          * really we are wasting a lot of work here.
 1415          *
 1416          * We don't use m_copy() because it might return a reference
 1417          * to a shared cluster. Both this function and ip_output()
 1418          * assume exclusive access to the IP header in `m', so any
 1419          * data in a cluster may change before we reach icmp_error().
 1420          */
 1421         MGETHDR(mcopy, M_DONTWAIT, m->m_type);
 1422         if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
 1423                 /*
 1424                  * It's probably ok if the pkthdr dup fails (because
 1425                  * the deep copy of the tag chain failed), but for now
 1426                  * be conservative and just discard the copy since
 1427                  * code below may some day want the tags.
 1428                  */
 1429                 m_free(mcopy);
 1430                 mcopy = NULL;
 1431         }
 1432         if (mcopy != NULL) {
 1433                 mcopy->m_len = min(ip->ip_len, M_TRAILINGSPACE(mcopy));
 1434                 mcopy->m_pkthdr.len = mcopy->m_len;
 1435                 m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
 1436         }
 1437 
 1438 #ifdef IPSTEALTH
 1439         if (!V_ipstealth) {
 1440 #endif
 1441                 ip->ip_ttl -= IPTTLDEC;
 1442 #ifdef IPSTEALTH
 1443         }
 1444 #endif
 1445 
 1446         /*
 1447          * If forwarding packet using same interface that it came in on,
 1448          * perhaps should send a redirect to sender to shortcut a hop.
 1449          * Only send redirect if source is sending directly to us,
 1450          * and if packet was not source routed (or has any options).
 1451          * Also, don't send redirect if forwarding using a default route
 1452          * or a route modified by a redirect.
 1453          */
 1454         dest.s_addr = 0;
 1455         if (!srcrt && V_ipsendredirects &&
 1456             ia != NULL && ia->ia_ifp == m->m_pkthdr.rcvif) {
 1457                 struct sockaddr_in *sin;
 1458                 struct rtentry *rt;
 1459 
 1460                 bzero(&ro, sizeof(ro));
 1461                 sin = (struct sockaddr_in *)&ro.ro_dst;
 1462                 sin->sin_family = AF_INET;
 1463                 sin->sin_len = sizeof(*sin);
 1464                 sin->sin_addr = ip->ip_dst;
 1465                 in_rtalloc_ign(&ro, 0, M_GETFIB(m));
 1466 
 1467                 rt = ro.ro_rt;
 1468 
 1469                 if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
 1470                     satosin(rt_key(rt))->sin_addr.s_addr != 0) {
 1471 #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
 1472                         u_long src = ntohl(ip->ip_src.s_addr);
 1473 
 1474                         if (RTA(rt) &&
 1475                             (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
 1476                                 if (rt->rt_flags & RTF_GATEWAY)
 1477                                         dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr;
 1478                                 else
 1479                                         dest.s_addr = ip->ip_dst.s_addr;
 1480                                 /* Router requirements says to only send host redirects */
 1481                                 type = ICMP_REDIRECT;
 1482                                 code = ICMP_REDIRECT_HOST;
 1483                         }
 1484                 }
 1485                 if (rt)
 1486                         RTFREE(rt);
 1487         }
 1488 
 1489         /*
 1490          * Try to cache the route MTU from ip_output so we can consider it for
 1491          * the ICMP_UNREACH_NEEDFRAG "Next-Hop MTU" field described in RFC1191.
 1492          */
 1493         bzero(&ro, sizeof(ro));
 1494 
 1495         error = ip_output(m, NULL, &ro, IP_FORWARDING, NULL, NULL);
 1496 
 1497         if (error == EMSGSIZE && ro.ro_rt)
 1498                 mtu = ro.ro_rt->rt_rmx.rmx_mtu;
 1499         RO_RTFREE(&ro);
 1500 
 1501         if (error)
 1502                 IPSTAT_INC(ips_cantforward);
 1503         else {
 1504                 IPSTAT_INC(ips_forward);
 1505                 if (type)
 1506                         IPSTAT_INC(ips_redirectsent);
 1507                 else {
 1508                         if (mcopy)
 1509                                 m_freem(mcopy);
 1510                         if (ia != NULL)
 1511                                 ifa_free(&ia->ia_ifa);
 1512                         return;
 1513                 }
 1514         }
 1515         if (mcopy == NULL) {
 1516                 if (ia != NULL)
 1517                         ifa_free(&ia->ia_ifa);
 1518                 return;
 1519         }
 1520 
 1521         switch (error) {
 1522 
 1523         case 0:                         /* forwarded, but need redirect */
 1524                 /* type, code set above */
 1525                 break;
 1526 
 1527         case ENETUNREACH:
 1528         case EHOSTUNREACH:
 1529         case ENETDOWN:
 1530         case EHOSTDOWN:
 1531         default:
 1532                 type = ICMP_UNREACH;
 1533                 code = ICMP_UNREACH_HOST;
 1534                 break;
 1535 
 1536         case EMSGSIZE:
 1537                 type = ICMP_UNREACH;
 1538                 code = ICMP_UNREACH_NEEDFRAG;
 1539 
 1540 #ifdef IPSEC
 1541                 /* 
 1542                  * If IPsec is configured for this path,
 1543                  * override any possibly mtu value set by ip_output.
 1544                  */ 
 1545                 mtu = ip_ipsec_mtu(mcopy, mtu);
 1546 #endif /* IPSEC */
 1547                 /*
 1548                  * If the MTU was set before make sure we are below the
 1549                  * interface MTU.
 1550                  * If the MTU wasn't set before use the interface mtu or
 1551                  * fall back to the next smaller mtu step compared to the
 1552                  * current packet size.
 1553                  */
 1554                 if (mtu != 0) {
 1555                         if (ia != NULL)
 1556                                 mtu = min(mtu, ia->ia_ifp->if_mtu);
 1557                 } else {
 1558                         if (ia != NULL)
 1559                                 mtu = ia->ia_ifp->if_mtu;
 1560                         else
 1561                                 mtu = ip_next_mtu(ip->ip_len, 0);
 1562                 }
 1563                 IPSTAT_INC(ips_cantfrag);
 1564                 break;
 1565 
 1566         case ENOBUFS:
 1567                 /*
 1568                  * A router should not generate ICMP_SOURCEQUENCH as
 1569                  * required in RFC1812 Requirements for IP Version 4 Routers.
 1570                  * Source quench could be a big problem under DoS attacks,
 1571                  * or if the underlying interface is rate-limited.
 1572                  * Those who need source quench packets may re-enable them
 1573                  * via the net.inet.ip.sendsourcequench sysctl.
 1574                  */
 1575                 if (V_ip_sendsourcequench == 0) {
 1576                         m_freem(mcopy);
 1577                         if (ia != NULL)
 1578                                 ifa_free(&ia->ia_ifa);
 1579                         return;
 1580                 } else {
 1581                         type = ICMP_SOURCEQUENCH;
 1582                         code = 0;
 1583                 }
 1584                 break;
 1585 
 1586         case EACCES:                    /* ipfw denied packet */
 1587                 m_freem(mcopy);
 1588                 if (ia != NULL)
 1589                         ifa_free(&ia->ia_ifa);
 1590                 return;
 1591         }
 1592         if (ia != NULL)
 1593                 ifa_free(&ia->ia_ifa);
 1594         icmp_error(mcopy, type, code, dest.s_addr, mtu);
 1595 }
 1596 
 1597 void
 1598 ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
 1599     struct mbuf *m)
 1600 {
 1601 
 1602         if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) {
 1603                 struct bintime bt;
 1604 
 1605                 bintime(&bt);
 1606                 if (inp->inp_socket->so_options & SO_BINTIME) {
 1607                         *mp = sbcreatecontrol((caddr_t) &bt, sizeof(bt),
 1608                         SCM_BINTIME, SOL_SOCKET);
 1609                         if (*mp)
 1610                                 mp = &(*mp)->m_next;
 1611                 }
 1612                 if (inp->inp_socket->so_options & SO_TIMESTAMP) {
 1613                         struct timeval tv;
 1614 
 1615                         bintime2timeval(&bt, &tv);
 1616                         *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
 1617                                 SCM_TIMESTAMP, SOL_SOCKET);
 1618                         if (*mp)
 1619                                 mp = &(*mp)->m_next;
 1620                 }
 1621         }
 1622         if (inp->inp_flags & INP_RECVDSTADDR) {
 1623                 *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
 1624                     sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
 1625                 if (*mp)
 1626                         mp = &(*mp)->m_next;
 1627         }
 1628         if (inp->inp_flags & INP_RECVTTL) {
 1629                 *mp = sbcreatecontrol((caddr_t) &ip->ip_ttl,
 1630                     sizeof(u_char), IP_RECVTTL, IPPROTO_IP);
 1631                 if (*mp)
 1632                         mp = &(*mp)->m_next;
 1633         }
 1634 #ifdef notyet
 1635         /* XXX
 1636          * Moving these out of udp_input() made them even more broken
 1637          * than they already were.
 1638          */
 1639         /* options were tossed already */
 1640         if (inp->inp_flags & INP_RECVOPTS) {
 1641                 *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
 1642                     sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
 1643                 if (*mp)
 1644                         mp = &(*mp)->m_next;
 1645         }
 1646         /* ip_srcroute doesn't do what we want here, need to fix */
 1647         if (inp->inp_flags & INP_RECVRETOPTS) {
 1648                 *mp = sbcreatecontrol((caddr_t) ip_srcroute(m),
 1649                     sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
 1650                 if (*mp)
 1651                         mp = &(*mp)->m_next;
 1652         }
 1653 #endif
 1654         if (inp->inp_flags & INP_RECVIF) {
 1655                 struct ifnet *ifp;
 1656                 struct sdlbuf {
 1657                         struct sockaddr_dl sdl;
 1658                         u_char  pad[32];
 1659                 } sdlbuf;
 1660                 struct sockaddr_dl *sdp;
 1661                 struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
 1662 
 1663                 if (((ifp = m->m_pkthdr.rcvif)) 
 1664                 && ( ifp->if_index && (ifp->if_index <= V_if_index))) {
 1665                         sdp = (struct sockaddr_dl *)ifp->if_addr->ifa_addr;
 1666                         /*
 1667                          * Change our mind and don't try copy.
 1668                          */
 1669                         if ((sdp->sdl_family != AF_LINK)
 1670                         || (sdp->sdl_len > sizeof(sdlbuf))) {
 1671                                 goto makedummy;
 1672                         }
 1673                         bcopy(sdp, sdl2, sdp->sdl_len);
 1674                 } else {
 1675 makedummy:      
 1676                         sdl2->sdl_len
 1677                                 = offsetof(struct sockaddr_dl, sdl_data[0]);
 1678                         sdl2->sdl_family = AF_LINK;
 1679                         sdl2->sdl_index = 0;
 1680                         sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
 1681                 }
 1682                 *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
 1683                         IP_RECVIF, IPPROTO_IP);
 1684                 if (*mp)
 1685                         mp = &(*mp)->m_next;
 1686         }
 1687         if (inp->inp_flags & INP_RECVTOS) {
 1688                 *mp = sbcreatecontrol((caddr_t) &ip->ip_tos,
 1689                     sizeof(u_char), IP_RECVTOS, IPPROTO_IP);
 1690                 if (*mp)
 1691                         mp = &(*mp)->m_next;
 1692         }
 1693 }
 1694 
 1695 /*
 1696  * XXXRW: Multicast routing code in ip_mroute.c is generally MPSAFE, but the
 1697  * ip_rsvp and ip_rsvp_on variables need to be interlocked with rsvp_on
 1698  * locking.  This code remains in ip_input.c as ip_mroute.c is optionally
 1699  * compiled.
 1700  */
 1701 static VNET_DEFINE(int, ip_rsvp_on);
 1702 VNET_DEFINE(struct socket *, ip_rsvpd);
 1703 
 1704 #define V_ip_rsvp_on            VNET(ip_rsvp_on)
 1705 
 1706 int
 1707 ip_rsvp_init(struct socket *so)
 1708 {
 1709 
 1710         if (so->so_type != SOCK_RAW ||
 1711             so->so_proto->pr_protocol != IPPROTO_RSVP)
 1712                 return EOPNOTSUPP;
 1713 
 1714         if (V_ip_rsvpd != NULL)
 1715                 return EADDRINUSE;
 1716 
 1717         V_ip_rsvpd = so;
 1718         /*
 1719          * This may seem silly, but we need to be sure we don't over-increment
 1720          * the RSVP counter, in case something slips up.
 1721          */
 1722         if (!V_ip_rsvp_on) {
 1723                 V_ip_rsvp_on = 1;
 1724                 V_rsvp_on++;
 1725         }
 1726 
 1727         return 0;
 1728 }
 1729 
 1730 int
 1731 ip_rsvp_done(void)
 1732 {
 1733 
 1734         V_ip_rsvpd = NULL;
 1735         /*
 1736          * This may seem silly, but we need to be sure we don't over-decrement
 1737          * the RSVP counter, in case something slips up.
 1738          */
 1739         if (V_ip_rsvp_on) {
 1740                 V_ip_rsvp_on = 0;
 1741                 V_rsvp_on--;
 1742         }
 1743         return 0;
 1744 }
 1745 
 1746 void
 1747 rsvp_input(struct mbuf *m, int off)     /* XXX must fixup manually */
 1748 {
 1749 
 1750         if (rsvp_input_p) { /* call the real one if loaded */
 1751                 rsvp_input_p(m, off);
 1752                 return;
 1753         }
 1754 
 1755         /* Can still get packets with rsvp_on = 0 if there is a local member
 1756          * of the group to which the RSVP packet is addressed.  But in this
 1757          * case we want to throw the packet away.
 1758          */
 1759         
 1760         if (!V_rsvp_on) {
 1761                 m_freem(m);
 1762                 return;
 1763         }
 1764 
 1765         if (V_ip_rsvpd != NULL) { 
 1766                 rip_input(m, off);
 1767                 return;
 1768         }
 1769         /* Drop the packet */
 1770         m_freem(m);
 1771 }

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