No empty .Rs/.Re

[netbsd-mini2440.git] / sys / netinet / ip_input.c

/*      $NetBSD: ip_input.c,v 1.283 2009/07/17 18:09:25 minskim Exp $   */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*-
 * Copyright (c) 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Public Access Networks Corporation ("Panix").  It was developed under
 * contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)ip_input.c  8.2 (Berkeley) 1/4/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.283 2009/07/17 18:09:25 minskim Exp $");

#include "opt_inet.h"
#include "opt_compat_netbsd.h"
#include "opt_gateway.h"
#include "opt_pfil_hooks.h"
#include "opt_ipsec.h"
#include "opt_mrouting.h"
#include "opt_mbuftrace.h"
#include "opt_inet_csum.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/pool.h>
#include <sys/sysctl.h>
#include <sys/kauth.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/pfil.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_proto.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_private.h>
#include <netinet/ip_icmp.h>
/* just for gif_ttl */
#include <netinet/in_gif.h>
#include "gif.h"
#include <net/if_gre.h>
#include "gre.h"

#ifdef MROUTING
#include <netinet/ip_mroute.h>
#endif

#ifdef IPSEC
#include <netinet6/ipsec.h>
#include <netinet6/ipsec_private.h>
#include <netkey/key.h>
#endif
#ifdef FAST_IPSEC
#include <netipsec/ipsec.h>
#include <netipsec/key.h>
#endif  /* FAST_IPSEC*/

#ifndef IPFORWARDING
#ifdef GATEWAY
#define IPFORWARDING    1       /* forward IP packets not for us */
#else /* GATEWAY */
#define IPFORWARDING    0       /* don't forward IP packets not for us */
#endif /* GATEWAY */
#endif /* IPFORWARDING */
#ifndef IPSENDREDIRECTS
#define IPSENDREDIRECTS 1
#endif
#ifndef IPFORWSRCRT
#define IPFORWSRCRT     1       /* forward source-routed packets */
#endif
#ifndef IPALLOWSRCRT
#define IPALLOWSRCRT    1       /* allow source-routed packets */
#endif
#ifndef IPMTUDISC
#define IPMTUDISC       1
#endif
#ifndef IPMTUDISCTIMEOUT
#define IPMTUDISCTIMEOUT (10 * 60)      /* as per RFC 1191 */
#endif

#ifdef COMPAT_50
#include <compat/sys/time.h>
#include <compat/sys/socket.h>
#endif

/*
 * Note: DIRECTED_BROADCAST is handled this way so that previous
 * configuration using this option will Just Work.
 */
#ifndef IPDIRECTEDBCAST
#ifdef DIRECTED_BROADCAST
#define IPDIRECTEDBCAST 1
#else
#define IPDIRECTEDBCAST 0
#endif /* DIRECTED_BROADCAST */
#endif /* IPDIRECTEDBCAST */
int     ipforwarding = IPFORWARDING;
int     ipsendredirects = IPSENDREDIRECTS;
int     ip_defttl = IPDEFTTL;
int     ip_forwsrcrt = IPFORWSRCRT;
int     ip_directedbcast = IPDIRECTEDBCAST;
int     ip_allowsrcrt = IPALLOWSRCRT;
int     ip_mtudisc = IPMTUDISC;
int     ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
#ifdef DIAGNOSTIC
int     ipprintfs = 0;
#endif

int     ip_do_randomid = 0;

/*
 * XXX - Setting ip_checkinterface mostly implements the receive side of
 * the Strong ES model described in RFC 1122, but since the routing table
 * and transmit implementation do not implement the Strong ES model,
 * setting this to 1 results in an odd hybrid.
 *
 * XXX - ip_checkinterface currently must be disabled if you use ipnat
 * to translate the destination address to another local interface.
 *
 * XXX - ip_checkinterface must be disabled if you add IP aliases
 * to the loopback interface instead of the interface where the
 * packets for those addresses are received.
 */
int     ip_checkinterface = 0;


struct rttimer_queue *ip_mtudisc_timeout_q = NULL;

int     ipqmaxlen = IFQ_MAXLEN;
u_long  in_ifaddrhash;                          /* size of hash table - 1 */
int     in_ifaddrentries;                       /* total number of addrs */
struct in_ifaddrhead in_ifaddrhead;
struct  in_ifaddrhashhead *in_ifaddrhashtbl;
u_long  in_multihash;                           /* size of hash table - 1 */
int     in_multientries;                        /* total number of addrs */
struct  in_multihashhead *in_multihashtbl;
struct  ifqueue ipintrq;
uint16_t ip_id;

percpu_t *ipstat_percpu;

#ifdef PFIL_HOOKS
struct pfil_head inet_pfil_hook;
#endif

/*
 * Cached copy of nmbclusters. If nbclusters is different,
 * recalculate IP parameters derived from nmbclusters.
 */
static int      ip_nmbclusters;                 /* copy of nmbclusters */
static void     ip_nmbclusters_changed(void);   /* recalc limits */

#define CHECK_NMBCLUSTER_PARAMS()                               \
do {                                                            \
        if (__predict_false(ip_nmbclusters != nmbclusters))     \
                ip_nmbclusters_changed();                       \
} while (/*CONSTCOND*/0)

/* IP datagram reassembly queues (hashed) */
#define IPREASS_NHASH_LOG2      6
#define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
#define IPREASS_HMASK           (IPREASS_NHASH - 1)
#define IPREASS_HASH(x,y) \
        (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
struct ipqhead ipq[IPREASS_NHASH];
int     ipq_locked;
static int      ip_nfragpackets;        /* packets in reass queue */
static int      ip_nfrags;              /* total fragments in reass queues */

int     ip_maxfragpackets = 200;        /* limit on packets. XXX sysctl */
int     ip_maxfrags;                    /* limit on fragments. XXX sysctl */


/*
 * Additive-Increase/Multiplicative-Decrease (AIMD) strategy for
 * IP reassembly queue buffer managment.
 *
 * We keep a count of total IP fragments (NB: not fragmented packets!)
 * awaiting reassembly (ip_nfrags) and a limit (ip_maxfrags) on fragments.
 * If ip_nfrags exceeds ip_maxfrags the limit, we drop half the
 * total fragments in  reassembly queues.This AIMD policy avoids
 * repeatedly deleting single packets under heavy fragmentation load
 * (e.g., from lossy NFS peers).
 */
static u_int    ip_reass_ttl_decr(u_int ticks);
static void     ip_reass_drophalf(void);


static inline int ipq_lock_try(void);
static inline void ipq_unlock(void);

static inline int
ipq_lock_try(void)
{
        int s;

        /*
         * Use splvm() -- we're blocking things that would cause
         * mbuf allocation.
         */
        s = splvm();
        if (ipq_locked) {
                splx(s);
                return (0);
        }
        ipq_locked = 1;
        splx(s);
        return (1);
}

static inline void
ipq_unlock(void)
{
        int s;

        s = splvm();
        ipq_locked = 0;
        splx(s);
}

#ifdef DIAGNOSTIC
#define IPQ_LOCK()                                                      \
do {                                                                    \
        if (ipq_lock_try() == 0) {                                      \
                printf("%s:%d: ipq already locked\n", __FILE__, __LINE__); \
                panic("ipq_lock");                                      \
        }                                                               \
} while (/*CONSTCOND*/ 0)
#define IPQ_LOCK_CHECK()                                                \
do {                                                                    \
        if (ipq_locked == 0) {                                          \
                printf("%s:%d: ipq lock not held\n", __FILE__, __LINE__); \
                panic("ipq lock check");                                \
        }                                                               \
} while (/*CONSTCOND*/ 0)
#else
#define IPQ_LOCK()              (void) ipq_lock_try()
#define IPQ_LOCK_CHECK()        /* nothing */
#endif

#define IPQ_UNLOCK()            ipq_unlock()

struct pool inmulti_pool;
struct pool ipqent_pool;

#ifdef INET_CSUM_COUNTERS
#include <sys/device.h>

struct evcnt ip_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "inet", "hwcsum bad");
struct evcnt ip_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "inet", "hwcsum ok");
struct evcnt ip_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "inet", "swcsum");

#define INET_CSUM_COUNTER_INCR(ev)      (ev)->ev_count++

EVCNT_ATTACH_STATIC(ip_hwcsum_bad);
EVCNT_ATTACH_STATIC(ip_hwcsum_ok);
EVCNT_ATTACH_STATIC(ip_swcsum);

#else

#define INET_CSUM_COUNTER_INCR(ev)      /* nothing */

#endif /* INET_CSUM_COUNTERS */

/*
 * We need to save the IP options in case a protocol wants to respond
 * to an incoming packet over the same route if the packet got here
 * using IP source routing.  This allows connection establishment and
 * maintenance when the remote end is on a network that is not known
 * to us.
 */
int     ip_nhops = 0;
static  struct ip_srcrt {
        struct  in_addr dst;                    /* final destination */
        char    nop;                            /* one NOP to align */
        char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
        struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
} ip_srcrt;

static void save_rte(u_char *, struct in_addr);

#ifdef MBUFTRACE
struct mowner ip_rx_mowner = MOWNER_INIT("internet", "rx");
struct mowner ip_tx_mowner = MOWNER_INIT("internet", "tx");
#endif

static void sysctl_net_inet_ip_setup(struct sysctllog **);

/*
 * Compute IP limits derived from the value of nmbclusters.
 */
static void
ip_nmbclusters_changed(void)
{
        ip_maxfrags = nmbclusters / 4;
        ip_nmbclusters =  nmbclusters;
}

/*
 * IP initialization: fill in IP protocol switch table.
 * All protocols not implemented in kernel go to raw IP protocol handler.
 */
void
ip_init(void)
{
        const struct protosw *pr;
        int i;

        sysctl_net_inet_ip_setup(NULL);

        pool_init(&inmulti_pool, sizeof(struct in_multi), 0, 0, 0, "inmltpl",
            NULL, IPL_SOFTNET);
        pool_init(&ipqent_pool, sizeof(struct ipqent), 0, 0, 0, "ipqepl",
            NULL, IPL_VM);

        pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
        if (pr == 0)
                panic("ip_init");
        for (i = 0; i < IPPROTO_MAX; i++)
                ip_protox[i] = pr - inetsw;
        for (pr = inetdomain.dom_protosw;
            pr < inetdomain.dom_protoswNPROTOSW; pr++)
                if (pr->pr_domain->dom_family == PF_INET &&
                    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
                        ip_protox[pr->pr_protocol] = pr - inetsw;

        for (i = 0; i < IPREASS_NHASH; i++)
                LIST_INIT(&ipq[i]);

        ip_initid();
        ip_id = time_second & 0xfffff;

        ipintrq.ifq_maxlen = ipqmaxlen;
        ip_nmbclusters_changed();

        TAILQ_INIT(&in_ifaddrhead);
        in_ifaddrhashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, true,
            &in_ifaddrhash);
        in_multihashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, true,
            &in_multihash);
        ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout);
#ifdef GATEWAY
        ipflow_init(ip_hashsize);
#endif

#ifdef PFIL_HOOKS
        /* Register our Packet Filter hook. */
        inet_pfil_hook.ph_type = PFIL_TYPE_AF;
        inet_pfil_hook.ph_af   = AF_INET;
        i = pfil_head_register(&inet_pfil_hook);
        if (i != 0)
                printf("ip_init: WARNING: unable to register pfil hook, "
                    "error %d\n", i);
#endif /* PFIL_HOOKS */

#ifdef MBUFTRACE
        MOWNER_ATTACH(&ip_tx_mowner);
        MOWNER_ATTACH(&ip_rx_mowner);
#endif /* MBUFTRACE */

        ipstat_percpu = percpu_alloc(sizeof(uint64_t) * IP_NSTATS);
}

struct  sockaddr_in ipaddr = {
        .sin_len = sizeof(ipaddr),
        .sin_family = AF_INET,
};
struct  route ipforward_rt;

/*
 * IP software interrupt routine
 */
void
ipintr(void)
{
        int s;
        struct mbuf *m;

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);
        while (!IF_IS_EMPTY(&ipintrq)) {
                s = splnet();
                IF_DEQUEUE(&ipintrq, m);
                splx(s);
                if (m == NULL)
                        break;
                ip_input(m);
        }
        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

/*
 * Ip input routine.  Checksum and byte swap header.  If fragmented
 * try to reassemble.  Process options.  Pass to next level.
 */
void
ip_input(struct mbuf *m)
{
        struct ip *ip = NULL;
        struct ipq *fp;
        struct in_ifaddr *ia;
        struct ifaddr *ifa;
        struct ipqent *ipqe;
        int hlen = 0, mff, len;
        int downmatch;
        int checkif;
        int srcrt = 0;
        int s;
        u_int hash;
#ifdef FAST_IPSEC
        struct m_tag *mtag;
        struct tdb_ident *tdbi;
        struct secpolicy *sp;
        int error;
#endif /* FAST_IPSEC */

        MCLAIM(m, &ip_rx_mowner);
#ifdef  DIAGNOSTIC
        if ((m->m_flags & M_PKTHDR) == 0)
                panic("ipintr no HDR");
#endif

        /*
         * If no IP addresses have been set yet but the interfaces
         * are receiving, can't do anything with incoming packets yet.
         */
        if (TAILQ_FIRST(&in_ifaddrhead) == 0)
                goto bad;
        IP_STATINC(IP_STAT_TOTAL);
        /*
         * If the IP header is not aligned, slurp it up into a new
         * mbuf with space for link headers, in the event we forward
         * it.  Otherwise, if it is aligned, make sure the entire
         * base IP header is in the first mbuf of the chain.
         */
        if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0) {
                if ((m = m_copyup(m, sizeof(struct ip),
                                  (max_linkhdr + 3) & ~3)) == NULL) {
                        /* XXXJRT new stat, please */
                        IP_STATINC(IP_STAT_TOOSMALL);
                        return;
                }
        } else if (__predict_false(m->m_len < sizeof (struct ip))) {
                if ((m = m_pullup(m, sizeof (struct ip))) == NULL) {
                        IP_STATINC(IP_STAT_TOOSMALL);
                        return;
                }
        }
        ip = mtod(m, struct ip *);
        if (ip->ip_v != IPVERSION) {
                IP_STATINC(IP_STAT_BADVERS);
                goto bad;
        }
        hlen = ip->ip_hl << 2;
        if (hlen < sizeof(struct ip)) { /* minimum header length */
                IP_STATINC(IP_STAT_BADHLEN);
                goto bad;
        }
        if (hlen > m->m_len) {
                if ((m = m_pullup(m, hlen)) == 0) {
                        IP_STATINC(IP_STAT_BADHLEN);
                        return;
                }
                ip = mtod(m, struct ip *);
        }

        /*
         * RFC1122: packets with a multicast source address are
         * not allowed.
         */
        if (IN_MULTICAST(ip->ip_src.s_addr)) {
                IP_STATINC(IP_STAT_BADADDR);
                goto bad;
        }

        /* 127/8 must not appear on wire - RFC1122 */
        if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
            (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
                if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
                        IP_STATINC(IP_STAT_BADADDR);
                        goto bad;
                }
        }

        switch (m->m_pkthdr.csum_flags &
                ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
                 M_CSUM_IPv4_BAD)) {
        case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
                INET_CSUM_COUNTER_INCR(&ip_hwcsum_bad);
                goto badcsum;

        case M_CSUM_IPv4:
                /* Checksum was okay. */
                INET_CSUM_COUNTER_INCR(&ip_hwcsum_ok);
                break;

        default:
                /*
                 * Must compute it ourselves.  Maybe skip checksum on
                 * loopback interfaces.
                 */
                if (__predict_true(!(m->m_pkthdr.rcvif->if_flags &
                                     IFF_LOOPBACK) || ip_do_loopback_cksum)) {
                        INET_CSUM_COUNTER_INCR(&ip_swcsum);
                        if (in_cksum(m, hlen) != 0)
                                goto badcsum;
                }
                break;
        }

        /* Retrieve the packet length. */
        len = ntohs(ip->ip_len);

        /*
         * Check for additional length bogosity
         */
        if (len < hlen) {
                IP_STATINC(IP_STAT_BADLEN);
                goto bad;
        }

        /*
         * Check that the amount of data in the buffers
         * is as at least much as the IP header would have us expect.
         * Trim mbufs if longer than we expect.
         * Drop packet if shorter than we expect.
         */
        if (m->m_pkthdr.len < len) {
                IP_STATINC(IP_STAT_TOOSHORT);
                goto bad;
        }
        if (m->m_pkthdr.len > len) {
                if (m->m_len == m->m_pkthdr.len) {
                        m->m_len = len;
                        m->m_pkthdr.len = len;
                } else
                        m_adj(m, len - m->m_pkthdr.len);
        }

#if defined(IPSEC)
        /* ipflow (IP fast forwarding) is not compatible with IPsec. */
        m->m_flags &= ~M_CANFASTFWD;
#else
        /*
         * Assume that we can create a fast-forward IP flow entry
         * based on this packet.
         */
        m->m_flags |= M_CANFASTFWD;
#endif

#ifdef PFIL_HOOKS
        /*
         * Run through list of hooks for input packets.  If there are any
         * filters which require that additional packets in the flow are
         * not fast-forwarded, they must clear the M_CANFASTFWD flag.
         * Note that filters must _never_ set this flag, as another filter
         * in the list may have previously cleared it.
         */
        /*
         * let ipfilter look at packet on the wire,
         * not the decapsulated packet.
         */
#ifdef IPSEC
        if (!ipsec_getnhist(m))
#elif defined(FAST_IPSEC)
        if (!ipsec_indone(m))
#else
        if (1)
#endif
        {
                struct in_addr odst;

                odst = ip->ip_dst;
                if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
                    PFIL_IN) != 0)
                        return;
                if (m == NULL)
                        return;
                ip = mtod(m, struct ip *);
                hlen = ip->ip_hl << 2;
                /*
                 * XXX The setting of "srcrt" here is to prevent ip_forward()
                 * from generating ICMP redirects for packets that have
                 * been redirected by a hook back out on to the same LAN that
                 * they came from and is not an indication that the packet
                 * is being inffluenced by source routing options.  This
                 * allows things like
                 * "rdr tlp0 0/0 port 80 -> 1.1.1.200 3128 tcp"
                 * where tlp0 is both on the 1.1.1.0/24 network and is the
                 * default route for hosts on 1.1.1.0/24.  Of course this
                 * also requires a "map tlp0 ..." to complete the story.
                 * One might argue whether or not this kind of network config.
                 * should be supported in this manner...
                 */
                srcrt = (odst.s_addr != ip->ip_dst.s_addr);
        }
#endif /* PFIL_HOOKS */

#ifdef ALTQ
        /* XXX Temporary until ALTQ is changed to use a pfil hook */
        if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) {
                /* packet dropped by traffic conditioner */
                return;
        }
#endif

        /*
         * Process options and, if not destined for us,
         * ship it on.  ip_dooptions returns 1 when an
         * error was detected (causing an icmp message
         * to be sent and the original packet to be freed).
         */
        ip_nhops = 0;           /* for source routed packets */
        if (hlen > sizeof (struct ip) && ip_dooptions(m))
                return;

        /*
         * Enable a consistency check between the destination address
         * and the arrival interface for a unicast packet (the RFC 1122
         * strong ES model) if IP forwarding is disabled and the packet
         * is not locally generated.
         *
         * XXX - Checking also should be disabled if the destination
         * address is ipnat'ed to a different interface.
         *
         * XXX - Checking is incompatible with IP aliases added
         * to the loopback interface instead of the interface where
         * the packets are received.
         *
         * XXX - We need to add a per ifaddr flag for this so that
         * we get finer grain control.
         */
        checkif = ip_checkinterface && (ipforwarding == 0) &&
            (m->m_pkthdr.rcvif != NULL) &&
            ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0);

        /*
         * Check our list of addresses, to see if the packet is for us.
         *
         * Traditional 4.4BSD did not consult IFF_UP at all.
         * The behavior here is to treat addresses on !IFF_UP interface
         * as not mine.
         */
        downmatch = 0;
        LIST_FOREACH(ia, &IN_IFADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
                if (in_hosteq(ia->ia_addr.sin_addr, ip->ip_dst)) {
                        if (checkif && ia->ia_ifp != m->m_pkthdr.rcvif)
                                continue;
                        if ((ia->ia_ifp->if_flags & IFF_UP) != 0)
                                break;
                        else
                                downmatch++;
                }
        }
        if (ia != NULL)
                goto ours;
        if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
                IFADDR_FOREACH(ifa, m->m_pkthdr.rcvif) {
                        if (ifa->ifa_addr->sa_family != AF_INET)
                                continue;
                        ia = ifatoia(ifa);
                        if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
                            in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
                            /*
                             * Look for all-0's host part (old broadcast addr),
                             * either for subnet or net.
                             */
                            ip->ip_dst.s_addr == ia->ia_subnet ||
                            ip->ip_dst.s_addr == ia->ia_net)
                                goto ours;
                        /*
                         * An interface with IP address zero accepts
                         * all packets that arrive on that interface.
                         */
                        if (in_nullhost(ia->ia_addr.sin_addr))
                                goto ours;
                }
        }
        if (IN_MULTICAST(ip->ip_dst.s_addr)) {
                struct in_multi *inm;
#ifdef MROUTING
                extern struct socket *ip_mrouter;

                if (ip_mrouter) {
                        /*
                         * If we are acting as a multicast router, all
                         * incoming multicast packets are passed to the
                         * kernel-level multicast forwarding function.
                         * The packet is returned (relatively) intact; if
                         * ip_mforward() returns a non-zero value, the packet
                         * must be discarded, else it may be accepted below.
                         *
                         * (The IP ident field is put in the same byte order
                         * as expected when ip_mforward() is called from
                         * ip_output().)
                         */
                        if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
                                IP_STATINC(IP_STAT_CANTFORWARD);
                                m_freem(m);
                                return;
                        }

                        /*
                         * The process-level routing demon needs to receive
                         * all multicast IGMP packets, whether or not this
                         * host belongs to their destination groups.
                         */
                        if (ip->ip_p == IPPROTO_IGMP)
                                goto ours;
                        IP_STATINC(IP_STAT_CANTFORWARD);
                }
#endif
                /*
                 * See if we belong to the destination multicast group on the
                 * arrival interface.
                 */
                IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
                if (inm == NULL) {
                        IP_STATINC(IP_STAT_CANTFORWARD);
                        m_freem(m);
                        return;
                }
                goto ours;
        }
        if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
            in_nullhost(ip->ip_dst))
                goto ours;

        /*
         * Not for us; forward if possible and desirable.
         */
        if (ipforwarding == 0) {
                IP_STATINC(IP_STAT_CANTFORWARD);
                m_freem(m);
        } else {
                /*
                 * If ip_dst matched any of my address on !IFF_UP interface,
                 * and there's no IFF_UP interface that matches ip_dst,
                 * send icmp unreach.  Forwarding it will result in in-kernel
                 * forwarding loop till TTL goes to 0.
                 */
                if (downmatch) {
                        icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
                        IP_STATINC(IP_STAT_CANTFORWARD);
                        return;
                }
#ifdef IPSEC
                if (ipsec4_in_reject(m, NULL)) {
                        IPSEC_STATINC(IPSEC_STAT_IN_POLVIO);
                        goto bad;
                }
#endif
#ifdef FAST_IPSEC
                mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
                s = splsoftnet();
                if (mtag != NULL) {
                        tdbi = (struct tdb_ident *)(mtag + 1);
                        sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
                } else {
                        sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
                                                   IP_FORWARDING, &error);
                }
                if (sp == NULL) {       /* NB: can happen if error */
                        splx(s);
                        /*XXX error stat???*/
                        DPRINTF(("ip_input: no SP for forwarding\n"));  /*XXX*/
                        goto bad;
                }

                /*
                 * Check security policy against packet attributes.
                 */
                error = ipsec_in_reject(sp, m);
                KEY_FREESP(&sp);
                splx(s);
                if (error) {
                        IP_STATINC(IP_STAT_CANTFORWARD);
                        goto bad;
                }

                /*
                 * Peek at the outbound SP for this packet to determine if
                 * it's a Fast Forward candidate.
                 */
                mtag = m_tag_find(m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
                if (mtag != NULL)
                        m->m_flags &= ~M_CANFASTFWD;
                else {
                        s = splsoftnet();
                        sp = ipsec4_checkpolicy(m, IPSEC_DIR_OUTBOUND,
                            (IP_FORWARDING |
                             (ip_directedbcast ? IP_ALLOWBROADCAST : 0)),
                            &error, NULL);
                        if (sp != NULL) {
                                m->m_flags &= ~M_CANFASTFWD;
                                KEY_FREESP(&sp);
                        }
                        splx(s);
                }
#endif  /* FAST_IPSEC */

                ip_forward(m, srcrt);
        }
        return;

ours:
        /*
         * If offset or IP_MF are set, must reassemble.
         * Otherwise, nothing need be done.
         * (We could look in the reassembly queue to see
         * if the packet was previously fragmented,
         * but it's not worth the time; just let them time out.)
         */
        if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
                uint16_t off;
                /*
                 * Prevent TCP blind data attacks by not allowing non-initial
                 * fragments to start at less than 68 bytes (minimal fragment
                 * size) and making sure the first fragment is at least 68
                 * bytes.
                 */
                off = (ntohs(ip->ip_off) & IP_OFFMASK) << 3;
                if ((off > 0 ? off + hlen : len) < IP_MINFRAGSIZE - 1) {
                        IP_STATINC(IP_STAT_BADFRAGS);
                        goto bad;
                }
                /*
                 * Look for queue of fragments
                 * of this datagram.
                 */
                IPQ_LOCK();
                hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
                LIST_FOREACH(fp, &ipq[hash], ipq_q) {
                        if (ip->ip_id == fp->ipq_id &&
                            in_hosteq(ip->ip_src, fp->ipq_src) &&
                            in_hosteq(ip->ip_dst, fp->ipq_dst) &&
                            ip->ip_p == fp->ipq_p) {
                                /*
                                 * Make sure the TOS is matches previous
                                 * fragments.
                                 */
                                if (ip->ip_tos != fp->ipq_tos) {
                                        IP_STATINC(IP_STAT_BADFRAGS);
                                        IPQ_UNLOCK();
                                        goto bad;
                                }
                                goto found;
                        }
                }
                fp = 0;
found:

                /*
                 * Adjust ip_len to not reflect header,
                 * set ipqe_mff if more fragments are expected,
                 * convert offset of this to bytes.
                 */
                ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
                mff = (ip->ip_off & htons(IP_MF)) != 0;
                if (mff) {
                        /*
                         * Make sure that fragments have a data length
                         * that's a non-zero multiple of 8 bytes.
                         */
                        if (ntohs(ip->ip_len) == 0 ||
                            (ntohs(ip->ip_len) & 0x7) != 0) {
                                IP_STATINC(IP_STAT_BADFRAGS);
                                IPQ_UNLOCK();
                                goto bad;
                        }
                }
                ip->ip_off = htons((ntohs(ip->ip_off) & IP_OFFMASK) << 3);

                /*
                 * If datagram marked as having more fragments
                 * or if this is not the first fragment,
                 * attempt reassembly; if it succeeds, proceed.
                 */
                if (mff || ip->ip_off != htons(0)) {
                        IP_STATINC(IP_STAT_FRAGMENTS);
                        s = splvm();
                        ipqe = pool_get(&ipqent_pool, PR_NOWAIT);
                        splx(s);
                        if (ipqe == NULL) {
                                IP_STATINC(IP_STAT_RCVMEMDROP);
                                IPQ_UNLOCK();
                                goto bad;
                        }
                        ipqe->ipqe_mff = mff;
                        ipqe->ipqe_m = m;
                        ipqe->ipqe_ip = ip;
                        m = ip_reass(ipqe, fp, &ipq[hash]);
                        if (m == 0) {
                                IPQ_UNLOCK();
                                return;
                        }
                        IP_STATINC(IP_STAT_REASSEMBLED);
                        ip = mtod(m, struct ip *);
                        hlen = ip->ip_hl << 2;
                        ip->ip_len = htons(ntohs(ip->ip_len) + hlen);
                } else
                        if (fp)
                                ip_freef(fp);
                IPQ_UNLOCK();
        }

#if defined(IPSEC)
        /*
         * enforce IPsec policy checking if we are seeing last header.
         * note that we do not visit this with protocols with pcb layer
         * code - like udp/tcp/raw ip.
         */
        if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
            ipsec4_in_reject(m, NULL)) {
                IPSEC_STATINC(IPSEC_STAT_IN_POLVIO);
                goto bad;
        }
#endif
#ifdef FAST_IPSEC
        /*
         * enforce IPsec policy checking if we are seeing last header.
         * note that we do not visit this with protocols with pcb layer
         * code - like udp/tcp/raw ip.
         */
        if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
                /*
                 * Check if the packet has already had IPsec processing
                 * done.  If so, then just pass it along.  This tag gets
                 * set during AH, ESP, etc. input handling, before the
                 * packet is returned to the ip input queue for delivery.
                 */
                mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
                s = splsoftnet();
                if (mtag != NULL) {
                        tdbi = (struct tdb_ident *)(mtag + 1);
                        sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
                } else {
                        sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
                                                   IP_FORWARDING, &error);
                }
                if (sp != NULL) {
                        /*
                         * Check security policy against packet attributes.
                         */
                        error = ipsec_in_reject(sp, m);
                        KEY_FREESP(&sp);
                } else {
                        /* XXX error stat??? */
                        error = EINVAL;
DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
                }
                splx(s);
                if (error)
                        goto bad;
        }
#endif /* FAST_IPSEC */

        /*
         * Switch out to protocol's input routine.
         */
#if IFA_STATS
        if (ia && ip)
                ia->ia_ifa.ifa_data.ifad_inbytes += ntohs(ip->ip_len);
#endif
        IP_STATINC(IP_STAT_DELIVERED);
    {
        int off = hlen, nh = ip->ip_p;

        (*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
        return;
    }
bad:
        m_freem(m);
        return;

badcsum:
        IP_STATINC(IP_STAT_BADSUM);
        m_freem(m);
}

/*
 * Take incoming datagram fragment and try to
 * reassemble it into whole datagram.  If a chain for
 * reassembly of this datagram already exists, then it
 * is given as fp; otherwise have to make a chain.
 */
struct mbuf *
ip_reass(struct ipqent *ipqe, struct ipq *fp, struct ipqhead *ipqhead)
{
        struct mbuf *m = ipqe->ipqe_m;
        struct ipqent *nq, *p, *q;
        struct ip *ip;
        struct mbuf *t;
        int hlen = ipqe->ipqe_ip->ip_hl << 2;
        int i, next, s;

        IPQ_LOCK_CHECK();

        /*
         * Presence of header sizes in mbufs
         * would confuse code below.
         */
        m->m_data += hlen;
        m->m_len -= hlen;

#ifdef  notyet
        /* make sure fragment limit is up-to-date */
        CHECK_NMBCLUSTER_PARAMS();

        /* If we have too many fragments, drop the older half. */
        if (ip_nfrags >= ip_maxfrags)
                ip_reass_drophalf(void);
#endif

        /*
         * We are about to add a fragment; increment frag count.
         */
        ip_nfrags++;

        /*
         * If first fragment to arrive, create a reassembly queue.
         */
        if (fp == 0) {
                /*
                 * Enforce upper bound on number of fragmented packets
                 * for which we attempt reassembly;
                 * If maxfrag is 0, never accept fragments.
                 * If maxfrag is -1, accept all fragments without limitation.
                 */
                if (ip_maxfragpackets < 0)
                        ;
                else if (ip_nfragpackets >= ip_maxfragpackets)
                        goto dropfrag;
                ip_nfragpackets++;
                fp = malloc(sizeof (struct ipq), M_FTABLE, M_NOWAIT);
                if (fp == NULL)
                        goto dropfrag;
                LIST_INSERT_HEAD(ipqhead, fp, ipq_q);
                fp->ipq_nfrags = 1;
                fp->ipq_ttl = IPFRAGTTL;
                fp->ipq_p = ipqe->ipqe_ip->ip_p;
                fp->ipq_id = ipqe->ipqe_ip->ip_id;
                fp->ipq_tos = ipqe->ipqe_ip->ip_tos;
                TAILQ_INIT(&fp->ipq_fragq);
                fp->ipq_src = ipqe->ipqe_ip->ip_src;
                fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
                p = NULL;
                goto insert;
        } else {
                fp->ipq_nfrags++;
        }

        /*
         * Find a segment which begins after this one does.
         */
        for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
            p = q, q = TAILQ_NEXT(q, ipqe_q))
                if (ntohs(q->ipqe_ip->ip_off) > ntohs(ipqe->ipqe_ip->ip_off))
                        break;

        /*
         * If there is a preceding segment, it may provide some of
         * our data already.  If so, drop the data from the incoming
         * segment.  If it provides all of our data, drop us.
         */
        if (p != NULL) {
                i = ntohs(p->ipqe_ip->ip_off) + ntohs(p->ipqe_ip->ip_len) -
                    ntohs(ipqe->ipqe_ip->ip_off);
                if (i > 0) {
                        if (i >= ntohs(ipqe->ipqe_ip->ip_len))
                                goto dropfrag;
                        m_adj(ipqe->ipqe_m, i);
                        ipqe->ipqe_ip->ip_off =
                            htons(ntohs(ipqe->ipqe_ip->ip_off) + i);
                        ipqe->ipqe_ip->ip_len =
                            htons(ntohs(ipqe->ipqe_ip->ip_len) - i);
                }
        }

        /*
         * While we overlap succeeding segments trim them or,
         * if they are completely covered, dequeue them.
         */
        for (; q != NULL &&
            ntohs(ipqe->ipqe_ip->ip_off) + ntohs(ipqe->ipqe_ip->ip_len) >
            ntohs(q->ipqe_ip->ip_off); q = nq) {
                i = (ntohs(ipqe->ipqe_ip->ip_off) +
                    ntohs(ipqe->ipqe_ip->ip_len)) - ntohs(q->ipqe_ip->ip_off);
                if (i < ntohs(q->ipqe_ip->ip_len)) {
                        q->ipqe_ip->ip_len =
                            htons(ntohs(q->ipqe_ip->ip_len) - i);
                        q->ipqe_ip->ip_off =
                            htons(ntohs(q->ipqe_ip->ip_off) + i);
                        m_adj(q->ipqe_m, i);
                        break;
                }
                nq = TAILQ_NEXT(q, ipqe_q);
                m_freem(q->ipqe_m);
                TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
                s = splvm();
                pool_put(&ipqent_pool, q);
                splx(s);
                fp->ipq_nfrags--;
                ip_nfrags--;
        }

insert:
        /*
         * Stick new segment in its place;
         * check for complete reassembly.
         */
        if (p == NULL) {
                TAILQ_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
        } else {
                TAILQ_INSERT_AFTER(&fp->ipq_fragq, p, ipqe, ipqe_q);
        }
        next = 0;
        for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
            p = q, q = TAILQ_NEXT(q, ipqe_q)) {
                if (ntohs(q->ipqe_ip->ip_off) != next)
                        return (0);
                next += ntohs(q->ipqe_ip->ip_len);
        }
        if (p->ipqe_mff)
                return (0);

        /*
         * Reassembly is complete.  Check for a bogus message size and
         * concatenate fragments.
         */
        q = TAILQ_FIRST(&fp->ipq_fragq);
        ip = q->ipqe_ip;
        if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
                IP_STATINC(IP_STAT_TOOLONG);
                ip_freef(fp);
                return (0);
        }
        m = q->ipqe_m;
        t = m->m_next;
        m->m_next = 0;
        m_cat(m, t);
        nq = TAILQ_NEXT(q, ipqe_q);
        s = splvm();
        pool_put(&ipqent_pool, q);
        splx(s);
        for (q = nq; q != NULL; q = nq) {
                t = q->ipqe_m;
                nq = TAILQ_NEXT(q, ipqe_q);
                s = splvm();
                pool_put(&ipqent_pool, q);
                splx(s);
                m_cat(m, t);
        }
        ip_nfrags -= fp->ipq_nfrags;

        /*
         * Create header for new ip packet by
         * modifying header of first packet;
         * dequeue and discard fragment reassembly header.
         * Make header visible.
         */
        ip->ip_len = htons(next);
        ip->ip_src = fp->ipq_src;
        ip->ip_dst = fp->ipq_dst;
        LIST_REMOVE(fp, ipq_q);
        free(fp, M_FTABLE);
        ip_nfragpackets--;
        m->m_len += (ip->ip_hl << 2);
        m->m_data -= (ip->ip_hl << 2);
        /* some debugging cruft by sklower, below, will go away soon */
        if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
                int plen = 0;
                for (t = m; t; t = t->m_next)
                        plen += t->m_len;
                m->m_pkthdr.len = plen;
                m->m_pkthdr.csum_flags = 0;
        }
        return (m);

dropfrag:
        if (fp != 0)
                fp->ipq_nfrags--;
        ip_nfrags--;
        IP_STATINC(IP_STAT_FRAGDROPPED);
        m_freem(m);
        s = splvm();
        pool_put(&ipqent_pool, ipqe);
        splx(s);
        return (0);
}

/*
 * Free a fragment reassembly header and all
 * associated datagrams.
 */
void
ip_freef(struct ipq *fp)
{
        struct ipqent *q, *p;
        u_int nfrags = 0;
        int s;

        IPQ_LOCK_CHECK();

        for (q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL; q = p) {
                p = TAILQ_NEXT(q, ipqe_q);
                m_freem(q->ipqe_m);
                nfrags++;
                TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
                s = splvm();
                pool_put(&ipqent_pool, q);
                splx(s);
        }

        if (nfrags != fp->ipq_nfrags)
            printf("ip_freef: nfrags %d != %d\n", fp->ipq_nfrags, nfrags);
        ip_nfrags -= nfrags;
        LIST_REMOVE(fp, ipq_q);
        free(fp, M_FTABLE);
        ip_nfragpackets--;
}

/*
 * IP reassembly TTL machinery for  multiplicative drop.
 */
static u_int    fragttl_histo[(IPFRAGTTL+1)];


/*
 * Decrement TTL of all reasembly queue entries by `ticks'.
 * Count number of distinct fragments (as opposed to partial, fragmented
 * datagrams) in the reassembly queue.  While we  traverse the entire
 * reassembly queue, compute and return the median TTL over all fragments.
 */
static u_int
ip_reass_ttl_decr(u_int ticks)
{
        u_int nfrags, median, dropfraction, keepfraction;
        struct ipq *fp, *nfp;
        int i;

        nfrags = 0;
        memset(fragttl_histo, 0, sizeof fragttl_histo);

        for (i = 0; i < IPREASS_NHASH; i++) {
                for (fp = LIST_FIRST(&ipq[i]); fp != NULL; fp = nfp) {
                        fp->ipq_ttl = ((fp->ipq_ttl  <= ticks) ?
                                       0 : fp->ipq_ttl - ticks);
                        nfp = LIST_NEXT(fp, ipq_q);
                        if (fp->ipq_ttl == 0) {
                                IP_STATINC(IP_STAT_FRAGTIMEOUT);
                                ip_freef(fp);
                        } else {
                                nfrags += fp->ipq_nfrags;
                                fragttl_histo[fp->ipq_ttl] += fp->ipq_nfrags;
                        }
                }
        }

        KASSERT(ip_nfrags == nfrags);

        /* Find median (or other drop fraction) in histogram. */
        dropfraction = (ip_nfrags / 2);
        keepfraction = ip_nfrags - dropfraction;
        for (i = IPFRAGTTL, median = 0; i >= 0; i--) {
                median +=  fragttl_histo[i];
                if (median >= keepfraction)
                        break;
        }

        /* Return TTL of median (or other fraction). */
        return (u_int)i;
}

void
ip_reass_drophalf(void)
{

        u_int median_ticks;
        /*
         * Compute median TTL of all fragments, and count frags
         * with that TTL or lower (roughly half of all fragments).
         */
        median_ticks = ip_reass_ttl_decr(0);

        /* Drop half. */
        median_ticks = ip_reass_ttl_decr(median_ticks);

}

/*
 * IP timer processing;
 * if a timer expires on a reassembly
 * queue, discard it.
 */
void
ip_slowtimo(void)
{
        static u_int dropscanidx = 0;
        u_int i;
        u_int median_ttl;

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);

        IPQ_LOCK();

        /* Age TTL of all fragments by 1 tick .*/
        median_ttl = ip_reass_ttl_decr(1);

        /* make sure fragment limit is up-to-date */
        CHECK_NMBCLUSTER_PARAMS();

        /* If we have too many fragments, drop the older half. */
        if (ip_nfrags > ip_maxfrags)
                ip_reass_ttl_decr(median_ttl);

        /*
         * If we are over the maximum number of fragmented packets
         * (due to the limit being lowered), drain off
         * enough to get down to the new limit. Start draining
         * from the reassembly hashqueue most recently drained.
         */
        if (ip_maxfragpackets < 0)
                ;
        else {
                int wrapped = 0;

                i = dropscanidx;
                while (ip_nfragpackets > ip_maxfragpackets && wrapped == 0) {
                        while (LIST_FIRST(&ipq[i]) != NULL)
                                ip_freef(LIST_FIRST(&ipq[i]));
                        if (++i >= IPREASS_NHASH) {
                                i = 0;
                        }
                        /*
                         * Dont scan forever even if fragment counters are
                         * wrong: stop after scanning entire reassembly queue.
                         */
                        if (i == dropscanidx)
                            wrapped = 1;
                }
                dropscanidx = i;
        }
        IPQ_UNLOCK();

        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);
}

/*
 * Drain off all datagram fragments.  Don't acquire softnet_lock as
 * can be called from hardware interrupt context.
 */
void
ip_drain(void)
{

        KERNEL_LOCK(1, NULL);

        /*
         * We may be called from a device's interrupt context.  If
         * the ipq is already busy, just bail out now.
         */
        if (ipq_lock_try() != 0) {
                /*
                 * Drop half the total fragments now. If more mbufs are
                 * needed, we will be called again soon.
                 */
                ip_reass_drophalf();
                IPQ_UNLOCK();
        }

        KERNEL_UNLOCK_ONE(NULL);
}

/*
 * Do option processing on a datagram,
 * possibly discarding it if bad options are encountered,
 * or forwarding it if source-routed.
 * Returns 1 if packet has been forwarded/freed,
 * 0 if the packet should be processed further.
 */
int
ip_dooptions(struct mbuf *m)
{
        struct ip *ip = mtod(m, struct ip *);
        u_char *cp, *cp0;
        struct ip_timestamp *ipt;
        struct in_ifaddr *ia;
        int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
        struct in_addr dst;
        n_time ntime;

        dst = ip->ip_dst;
        cp = (u_char *)(ip + 1);
        cnt = (ip->ip_hl << 2) - sizeof (struct ip);
        for (; cnt > 0; cnt -= optlen, cp += optlen) {
                opt = cp[IPOPT_OPTVAL];
                if (opt == IPOPT_EOL)
                        break;
                if (opt == IPOPT_NOP)
                        optlen = 1;
                else {
                        if (cnt < IPOPT_OLEN + sizeof(*cp)) {
                                code = &cp[IPOPT_OLEN] - (u_char *)ip;
                                goto bad;
                        }
                        optlen = cp[IPOPT_OLEN];
                        if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
                                code = &cp[IPOPT_OLEN] - (u_char *)ip;
                                goto bad;
                        }
                }
                switch (opt) {

                default:
                        break;

                /*
                 * Source routing with record.
                 * Find interface with current destination address.
                 * If none on this machine then drop if strictly routed,
                 * or do nothing if loosely routed.
                 * Record interface address and bring up next address
                 * component.  If strictly routed make sure next
                 * address is on directly accessible net.
                 */
                case IPOPT_LSRR:
                case IPOPT_SSRR:
                        if (ip_allowsrcrt == 0) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_NET_PROHIB;
                                goto bad;
                        }
                        if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
                                code = &cp[IPOPT_OLEN] - (u_char *)ip;
                                goto bad;
                        }
                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                                goto bad;
                        }
                        ipaddr.sin_addr = ip->ip_dst;
                        ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
                        if (ia == 0) {
                                if (opt == IPOPT_SSRR) {
                                        type = ICMP_UNREACH;
                                        code = ICMP_UNREACH_SRCFAIL;
                                        goto bad;
                                }
                                /*
                                 * Loose routing, and not at next destination
                                 * yet; nothing to do except forward.
                                 */
                                break;
                        }
                        off--;                  /* 0 origin */
                        if ((off + sizeof(struct in_addr)) > optlen) {
                                /*
                                 * End of source route.  Should be for us.
                                 */
                                save_rte(cp, ip->ip_src);
                                break;
                        }
                        /*
                         * locate outgoing interface
                         */
                        memcpy((void *)&ipaddr.sin_addr, (void *)(cp + off),
                            sizeof(ipaddr.sin_addr));
                        if (opt == IPOPT_SSRR)
                                ia = ifatoia(ifa_ifwithladdr(sintosa(&ipaddr)));
                        else
                                ia = ip_rtaddr(ipaddr.sin_addr);
                        if (ia == 0) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_SRCFAIL;
                                goto bad;
                        }
                        ip->ip_dst = ipaddr.sin_addr;
                        bcopy((void *)&ia->ia_addr.sin_addr,
                            (void *)(cp + off), sizeof(struct in_addr));
                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                        /*
                         * Let ip_intr's mcast routing check handle mcast pkts
                         */
                        forward = !IN_MULTICAST(ip->ip_dst.s_addr);
                        break;

                case IPOPT_RR:
                        if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
                                code = &cp[IPOPT_OLEN] - (u_char *)ip;
                                goto bad;
                        }
                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                                goto bad;
                        }
                        /*
                         * If no space remains, ignore.
                         */
                        off--;                  /* 0 origin */
                        if ((off + sizeof(struct in_addr)) > optlen)
                                break;
                        memcpy((void *)&ipaddr.sin_addr, (void *)(&ip->ip_dst),
                            sizeof(ipaddr.sin_addr));
                        /*
                         * locate outgoing interface; if we're the destination,
                         * use the incoming interface (should be same).
                         */
                        if ((ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr))))
                            == NULL &&
                            (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_HOST;
                                goto bad;
                        }
                        bcopy((void *)&ia->ia_addr.sin_addr,
                            (void *)(cp + off), sizeof(struct in_addr));
                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                        break;

                case IPOPT_TS:
                        code = cp - (u_char *)ip;
                        ipt = (struct ip_timestamp *)cp;
                        if (ipt->ipt_len < 4 || ipt->ipt_len > 40) {
                                code = (u_char *)&ipt->ipt_len - (u_char *)ip;
                                goto bad;
                        }
                        if (ipt->ipt_ptr < 5) {
                                code = (u_char *)&ipt->ipt_ptr - (u_char *)ip;
                                goto bad;
                        }
                        if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
                                if (++ipt->ipt_oflw == 0) {
                                        code = (u_char *)&ipt->ipt_ptr -
                                            (u_char *)ip;
                                        goto bad;
                                }
                                break;
                        }
                        cp0 = (cp + ipt->ipt_ptr - 1);
                        switch (ipt->ipt_flg) {

                        case IPOPT_TS_TSONLY:
                                break;

                        case IPOPT_TS_TSANDADDR:
                                if (ipt->ipt_ptr - 1 + sizeof(n_time) +
                                    sizeof(struct in_addr) > ipt->ipt_len) {
                                        code = (u_char *)&ipt->ipt_ptr -
                                            (u_char *)ip;
                                        goto bad;
                                }
                                ipaddr.sin_addr = dst;
                                ia = ifatoia(ifaof_ifpforaddr(sintosa(&ipaddr),
                                    m->m_pkthdr.rcvif));
                                if (ia == 0)
                                        continue;
                                bcopy(&ia->ia_addr.sin_addr,
                                    cp0, sizeof(struct in_addr));
                                ipt->ipt_ptr += sizeof(struct in_addr);
                                break;

                        case IPOPT_TS_PRESPEC:
                                if (ipt->ipt_ptr - 1 + sizeof(n_time) +
                                    sizeof(struct in_addr) > ipt->ipt_len) {
                                        code = (u_char *)&ipt->ipt_ptr -
                                            (u_char *)ip;
                                        goto bad;
                                }
                                memcpy(&ipaddr.sin_addr, cp0,
                                    sizeof(struct in_addr));
                                if (ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)))
                                    == NULL)
                                        continue;
                                ipt->ipt_ptr += sizeof(struct in_addr);
                                break;

                        default:
                                /* XXX can't take &ipt->ipt_flg */
                                code = (u_char *)&ipt->ipt_ptr -
                                    (u_char *)ip + 1;
                                goto bad;
                        }
                        ntime = iptime();
                        cp0 = (u_char *) &ntime; /* XXX grumble, GCC... */
                        memmove((char *)cp + ipt->ipt_ptr - 1, cp0,
                            sizeof(n_time));
                        ipt->ipt_ptr += sizeof(n_time);
                }
        }
        if (forward) {
                if (ip_forwsrcrt == 0) {
                        type = ICMP_UNREACH;
                        code = ICMP_UNREACH_SRCFAIL;
                        goto bad;
                }
                ip_forward(m, 1);
                return (1);
        }
        return (0);
bad:
        icmp_error(m, type, code, 0, 0);
        IP_STATINC(IP_STAT_BADOPTIONS);
        return (1);
}

/*
 * Given address of next destination (final or next hop),
 * return internet address info of interface to be used to get there.
 */
struct in_ifaddr *
ip_rtaddr(struct in_addr dst)
{
        struct rtentry *rt;
        union {
                struct sockaddr         dst;
                struct sockaddr_in      dst4;
        } u;

        sockaddr_in_init(&u.dst4, &dst, 0);

        if ((rt = rtcache_lookup(&ipforward_rt, &u.dst)) == NULL)
                return NULL;

        return ifatoia(rt->rt_ifa);
}

/*
 * Save incoming source route for use in replies,
 * to be picked up later by ip_srcroute if the receiver is interested.
 */
void
save_rte(u_char *option, struct in_addr dst)
{
        unsigned olen;

        olen = option[IPOPT_OLEN];
#ifdef DIAGNOSTIC
        if (ipprintfs)
                printf("save_rte: olen %d\n", olen);
#endif /* 0 */
        if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
                return;
        memcpy((void *)ip_srcrt.srcopt, (void *)option, olen);
        ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
        ip_srcrt.dst = dst;
}

/*
 * Retrieve incoming source route for use in replies,
 * in the same form used by setsockopt.
 * The first hop is placed before the options, will be removed later.
 */
struct mbuf *
ip_srcroute(void)
{
        struct in_addr *p, *q;
        struct mbuf *m;

        if (ip_nhops == 0)
                return NULL;
        m = m_get(M_DONTWAIT, MT_SOOPTS);
        if (m == 0)
                return NULL;

        MCLAIM(m, &inetdomain.dom_mowner);
#define OPTSIZ  (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))

        /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
        m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
            OPTSIZ;
#ifdef DIAGNOSTIC
        if (ipprintfs)
                printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
#endif

        /*
         * First save first hop for return route
         */
        p = &ip_srcrt.route[ip_nhops - 1];
        *(mtod(m, struct in_addr *)) = *p--;
#ifdef DIAGNOSTIC
        if (ipprintfs)
                printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
#endif

        /*
         * Copy option fields and padding (nop) to mbuf.
         */
        ip_srcrt.nop = IPOPT_NOP;
        ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
        memmove(mtod(m, char *) + sizeof(struct in_addr), &ip_srcrt.nop,
            OPTSIZ);
        q = (struct in_addr *)(mtod(m, char *) +
            sizeof(struct in_addr) + OPTSIZ);
#undef OPTSIZ
        /*
         * Record return path as an IP source route,
         * reversing the path (pointers are now aligned).
         */
        while (p >= ip_srcrt.route) {
#ifdef DIAGNOSTIC
                if (ipprintfs)
                        printf(" %x", ntohl(q->s_addr));
#endif
                *q++ = *p--;
        }
        /*
         * Last hop goes to final destination.
         */
        *q = ip_srcrt.dst;
#ifdef DIAGNOSTIC
        if (ipprintfs)
                printf(" %x\n", ntohl(q->s_addr));
#endif
        return (m);
}

const int inetctlerrmap[PRC_NCMDS] = {
        [PRC_MSGSIZE] = EMSGSIZE,
        [PRC_HOSTDEAD] = EHOSTDOWN,
        [PRC_HOSTUNREACH] = EHOSTUNREACH,
        [PRC_UNREACH_NET] = EHOSTUNREACH,
        [PRC_UNREACH_HOST] = EHOSTUNREACH,
        [PRC_UNREACH_PROTOCOL] = ECONNREFUSED,
        [PRC_UNREACH_PORT] = ECONNREFUSED,
        [PRC_UNREACH_SRCFAIL] = EHOSTUNREACH,
        [PRC_PARAMPROB] = ENOPROTOOPT,
};

/*
 * Forward a packet.  If some error occurs return the sender
 * an icmp packet.  Note we can't always generate a meaningful
 * icmp message because icmp doesn't have a large enough repertoire
 * of codes and types.
 *
 * If not forwarding, just drop the packet.  This could be confusing
 * if ipforwarding was zero but some routing protocol was advancing
 * us as a gateway to somewhere.  However, we must let the routing
 * protocol deal with that.
 *
 * The srcrt parameter indicates whether the packet is being forwarded
 * via a source route.
 */
void
ip_forward(struct mbuf *m, int srcrt)
{
        struct ip *ip = mtod(m, struct ip *);
        struct rtentry *rt;
        int error, type = 0, code = 0, destmtu = 0;
        struct mbuf *mcopy;
        n_long dest;
        union {
                struct sockaddr         dst;
                struct sockaddr_in      dst4;
        } u;

        /*
         * We are now in the output path.
         */
        MCLAIM(m, &ip_tx_mowner);

        /*
         * Clear any in-bound checksum flags for this packet.
         */
        m->m_pkthdr.csum_flags = 0;

        dest = 0;
#ifdef DIAGNOSTIC
        if (ipprintfs) {
                printf("forward: src %s ", inet_ntoa(ip->ip_src));
                printf("dst %s ttl %x\n", inet_ntoa(ip->ip_dst), ip->ip_ttl);
        }
#endif
        if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
                IP_STATINC(IP_STAT_CANTFORWARD);
                m_freem(m);
                return;
        }
        if (ip->ip_ttl <= IPTTLDEC) {
                icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
                return;
        }

        sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
        if ((rt = rtcache_lookup(&ipforward_rt, &u.dst)) == NULL) {
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, dest, 0);
                return;
        }

        /*
         * Save at most 68 bytes of the packet in case
         * we need to generate an ICMP message to the src.
         * Pullup to avoid sharing mbuf cluster between m and mcopy.
         */
        mcopy = m_copym(m, 0, imin(ntohs(ip->ip_len), 68), M_DONTWAIT);
        if (mcopy)
                mcopy = m_pullup(mcopy, ip->ip_hl << 2);

        ip->ip_ttl -= IPTTLDEC;

        /*
         * If forwarding packet using same interface that it came in on,
         * perhaps should send a redirect to sender to shortcut a hop.
         * Only send redirect if source is sending directly to us,
         * and if packet was not source routed (or has any options).
         * Also, don't send redirect if forwarding using a default route
         * or a route modified by a redirect.
         */
        if (rt->rt_ifp == m->m_pkthdr.rcvif &&
            (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
            !in_nullhost(satocsin(rt_getkey(rt))->sin_addr) &&
            ipsendredirects && !srcrt) {
                if (rt->rt_ifa &&
                    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
                    ifatoia(rt->rt_ifa)->ia_subnet) {
                        if (rt->rt_flags & RTF_GATEWAY)
                                dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
                        else
                                dest = ip->ip_dst.s_addr;
                        /*
                         * Router requirements says to only send host
                         * redirects.
                         */
                        type = ICMP_REDIRECT;
                        code = ICMP_REDIRECT_HOST;
#ifdef DIAGNOSTIC
                        if (ipprintfs)
                                printf("redirect (%d) to %x\n", code,
                                    (u_int32_t)dest);
#endif
                }
        }

        error = ip_output(m, NULL, &ipforward_rt,
            (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)),
            (struct ip_moptions *)NULL, (struct socket *)NULL);

        if (error)
                IP_STATINC(IP_STAT_CANTFORWARD);
        else {
                uint64_t *ips = IP_STAT_GETREF();
                ips[IP_STAT_FORWARD]++;
                if (type) {
                        ips[IP_STAT_REDIRECTSENT]++;
                        IP_STAT_PUTREF();
                } else {
                        IP_STAT_PUTREF();
                        if (mcopy) {
#ifdef GATEWAY
                                if (mcopy->m_flags & M_CANFASTFWD)
                                        ipflow_create(&ipforward_rt, mcopy);
#endif
                                m_freem(mcopy);
                        }
                        return;
                }
        }
        if (mcopy == NULL)
                return;

        switch (error) {

        case 0:                         /* forwarded, but need redirect */
                /* type, code set above */
                break;

        case ENETUNREACH:               /* shouldn't happen, checked above */
        case EHOSTUNREACH:
        case ENETDOWN:
        case EHOSTDOWN:
        default:
                type = ICMP_UNREACH;
                code = ICMP_UNREACH_HOST;
                break;

        case EMSGSIZE:
                type = ICMP_UNREACH;
                code = ICMP_UNREACH_NEEDFRAG;

                if ((rt = rtcache_validate(&ipforward_rt)) != NULL)
                        destmtu = rt->rt_ifp->if_mtu;

#if defined(IPSEC) || defined(FAST_IPSEC)
                {
                        /*
                         * If the packet is routed over IPsec tunnel, tell the
                         * originator the tunnel MTU.
                         *      tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
                         * XXX quickhack!!!
                         */

                        struct secpolicy *sp;
                        int ipsecerror;
                        size_t ipsechdr;
                        struct route *ro;

                        sp = ipsec4_getpolicybyaddr(mcopy,
                            IPSEC_DIR_OUTBOUND, IP_FORWARDING,
                            &ipsecerror);

                        if (sp != NULL) {
                                /* count IPsec header size */
                                ipsechdr = ipsec4_hdrsiz(mcopy,
                                    IPSEC_DIR_OUTBOUND, NULL);

                                /*
                                 * find the correct route for outer IPv4
                                 * header, compute tunnel MTU.
                                 */

                                if (sp->req != NULL
                                 && sp->req->sav != NULL
                                 && sp->req->sav->sah != NULL) {
                                        ro = &sp->req->sav->sah->sa_route;
                                        rt = rtcache_validate(ro);
                                        if (rt && rt->rt_ifp) {
                                                destmtu =
                                                    rt->rt_rmx.rmx_mtu ?
                                                    rt->rt_rmx.rmx_mtu :
                                                    rt->rt_ifp->if_mtu;
                                                destmtu -= ipsechdr;
                                        }
                                }

#ifdef  IPSEC
                                key_freesp(sp);
#else
                                KEY_FREESP(&sp);
#endif
                        }
                }
#endif /*defined(IPSEC) || defined(FAST_IPSEC)*/
                IP_STATINC(IP_STAT_CANTFRAG);
                break;

        case ENOBUFS:
#if 1
                /*
                 * a router should not generate ICMP_SOURCEQUENCH as
                 * required in RFC1812 Requirements for IP Version 4 Routers.
                 * source quench could be a big problem under DoS attacks,
                 * or if the underlying interface is rate-limited.
                 */
                if (mcopy)
                        m_freem(mcopy);
                return;
#else
                type = ICMP_SOURCEQUENCH;
                code = 0;
                break;
#endif
        }
        icmp_error(mcopy, type, code, dest, destmtu);
}

void
ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
    struct mbuf *m)
{

        if (inp->inp_socket->so_options & SO_TIMESTAMP
#ifdef SO_OTIMESTAMP
            || inp->inp_socket->so_options & SO_OTIMESTAMP
#endif
            ) {
                struct timeval tv;

                microtime(&tv);
#ifdef SO_OTIMESTAMP
                if (inp->inp_socket->so_options & SO_OTIMESTAMP) {
                        struct timeval50 tv50;
                        timeval_to_timeval50(&tv, &tv50);
                        *mp = sbcreatecontrol((void *) &tv50, sizeof(tv50),
                            SCM_OTIMESTAMP, SOL_SOCKET);
                } else
#endif
                *mp = sbcreatecontrol((void *) &tv, sizeof(tv),
                    SCM_TIMESTAMP, SOL_SOCKET);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
        if (inp->inp_flags & INP_RECVDSTADDR) {
                *mp = sbcreatecontrol((void *) &ip->ip_dst,
                    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
#ifdef notyet
        /*
         * XXX
         * Moving these out of udp_input() made them even more broken
         * than they already were.
         *      - fenner@parc.xerox.com
         */
        /* options were tossed already */
        if (inp->inp_flags & INP_RECVOPTS) {
                *mp = sbcreatecontrol((void *) opts_deleted_above,
                    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
        /* ip_srcroute doesn't do what we want here, need to fix */
        if (inp->inp_flags & INP_RECVRETOPTS) {
                *mp = sbcreatecontrol((void *) ip_srcroute(),
                    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
#endif
        if (inp->inp_flags & INP_RECVIF) {
                struct sockaddr_dl sdl;

                sockaddr_dl_init(&sdl, sizeof(sdl),
                    (m->m_pkthdr.rcvif != NULL)
                        ?  m->m_pkthdr.rcvif->if_index
                        : 0,
                        0, NULL, 0, NULL, 0);
                *mp = sbcreatecontrol(&sdl, sdl.sdl_len, IP_RECVIF, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
        if (inp->inp_flags & INP_RECVTTL) {
                *mp = sbcreatecontrol((void *) &ip->ip_ttl,
                    sizeof(uint8_t), IP_RECVTTL, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
}

/*
 * sysctl helper routine for net.inet.ip.forwsrcrt.
 */
static int
sysctl_net_inet_ip_forwsrcrt(SYSCTLFN_ARGS)
{
        int error, tmp;
        struct sysctlnode node;

        node = *rnode;
        tmp = ip_forwsrcrt;
        node.sysctl_data = &tmp;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return (error);

        error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_FORWSRCRT,
            0, NULL, NULL, NULL);
        if (error)
                return (error);

        ip_forwsrcrt = tmp;

        return (0);
}

/*
 * sysctl helper routine for net.inet.ip.mtudisctimeout.  checks the
 * range of the new value and tweaks timers if it changes.
 */
static int
sysctl_net_inet_ip_pmtudto(SYSCTLFN_ARGS)
{
        int error, tmp;
        struct sysctlnode node;

        node = *rnode;
        tmp = ip_mtudisc_timeout;
        node.sysctl_data = &tmp;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return (error);
        if (tmp < 0)
                return (EINVAL);

        mutex_enter(softnet_lock);

        ip_mtudisc_timeout = tmp;
        rt_timer_queue_change(ip_mtudisc_timeout_q, ip_mtudisc_timeout);

        mutex_exit(softnet_lock);

        return (0);
}

#ifdef GATEWAY
/*
 * sysctl helper routine for net.inet.ip.maxflows.
 */
static int
sysctl_net_inet_ip_maxflows(SYSCTLFN_ARGS)
{
        int error;

        error = sysctl_lookup(SYSCTLFN_CALL(rnode));
        if (error || newp == NULL)
                return (error);

        mutex_enter(softnet_lock);
        KERNEL_LOCK(1, NULL);

        ipflow_prune();

        KERNEL_UNLOCK_ONE(NULL);
        mutex_exit(softnet_lock);

        return (0);
}

static int
sysctl_net_inet_ip_hashsize(SYSCTLFN_ARGS)
{
        int error, tmp;
        struct sysctlnode node;

        node = *rnode;
        tmp = ip_hashsize;
        node.sysctl_data = &tmp;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return (error);

        if ((tmp & (tmp - 1)) == 0 && tmp != 0) {
                /*
                 * Can only fail due to malloc()
                 */
                mutex_enter(softnet_lock);
                KERNEL_LOCK(1, NULL);

                error = ipflow_invalidate_all(tmp);

                KERNEL_UNLOCK_ONE(NULL);
                mutex_exit(softnet_lock);

        } else {
                /*
                 * EINVAL if not a power of 2
                 */
                error = EINVAL;
        }

        return error;
}
#endif /* GATEWAY */

static int
sysctl_net_inet_ip_stats(SYSCTLFN_ARGS)
{

        return (NETSTAT_SYSCTL(ipstat_percpu, IP_NSTATS));
}

static void
sysctl_net_inet_ip_setup(struct sysctllog **clog)
{
        extern int subnetsarelocal, hostzeroisbroadcast;

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "net", NULL,
                       NULL, 0, NULL, 0,
                       CTL_NET, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "inet",
                       SYSCTL_DESCR("PF_INET related settings"),
                       NULL, 0, NULL, 0,
                       CTL_NET, PF_INET, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "ip",
                       SYSCTL_DESCR("IPv4 related settings"),
                       NULL, 0, NULL, 0,
                       CTL_NET, PF_INET, IPPROTO_IP, CTL_EOL);

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "forwarding",
                       SYSCTL_DESCR("Enable forwarding of INET datagrams"),
                       NULL, 0, &ipforwarding, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_FORWARDING, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "redirect",
                       SYSCTL_DESCR("Enable sending of ICMP redirect messages"),
                       NULL, 0, &ipsendredirects, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_SENDREDIRECTS, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "ttl",
                       SYSCTL_DESCR("Default TTL for an INET datagram"),
                       NULL, 0, &ip_defttl, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_DEFTTL, CTL_EOL);
#ifdef IPCTL_DEFMTU
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT /* |CTLFLAG_READWRITE? */,
                       CTLTYPE_INT, "mtu",
                       SYSCTL_DESCR("Default MTA for an INET route"),
                       NULL, 0, &ip_mtu, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_DEFMTU, CTL_EOL);
#endif /* IPCTL_DEFMTU */
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "forwsrcrt",
                       SYSCTL_DESCR("Enable forwarding of source-routed "
                                    "datagrams"),
                       sysctl_net_inet_ip_forwsrcrt, 0, &ip_forwsrcrt, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_FORWSRCRT, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "directed-broadcast",
                       SYSCTL_DESCR("Enable forwarding of broadcast datagrams"),
                       NULL, 0, &ip_directedbcast, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_DIRECTEDBCAST, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "allowsrcrt",
                       SYSCTL_DESCR("Accept source-routed datagrams"),
                       NULL, 0, &ip_allowsrcrt, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_ALLOWSRCRT, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "subnetsarelocal",
                       SYSCTL_DESCR("Whether logical subnets are considered "
                                    "local"),
                       NULL, 0, &subnetsarelocal, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_SUBNETSARELOCAL, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "mtudisc",
                       SYSCTL_DESCR("Use RFC1191 Path MTU Discovery"),
                       NULL, 0, &ip_mtudisc, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_MTUDISC, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "anonportmin",
                       SYSCTL_DESCR("Lowest ephemeral port number to assign"),
                       sysctl_net_inet_ip_ports, 0, &anonportmin, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_ANONPORTMIN, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "anonportmax",
                       SYSCTL_DESCR("Highest ephemeral port number to assign"),
                       sysctl_net_inet_ip_ports, 0, &anonportmax, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_ANONPORTMAX, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "mtudisctimeout",
                       SYSCTL_DESCR("Lifetime of a Path MTU Discovered route"),
                       sysctl_net_inet_ip_pmtudto, 0, &ip_mtudisc_timeout, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_MTUDISCTIMEOUT, CTL_EOL);
#ifdef GATEWAY
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "maxflows",
                       SYSCTL_DESCR("Number of flows for fast forwarding"),
                       sysctl_net_inet_ip_maxflows, 0, &ip_maxflows, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_MAXFLOWS, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                        CTLTYPE_INT, "hashsize",
                        SYSCTL_DESCR("Size of hash table for fast forwarding (IPv4)"),
                        sysctl_net_inet_ip_hashsize, 0, &ip_hashsize, 0,
                        CTL_NET, PF_INET, IPPROTO_IP,
                        CTL_CREATE, CTL_EOL);
#endif /* GATEWAY */
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "hostzerobroadcast",
                       SYSCTL_DESCR("All zeroes address is broadcast address"),
                       NULL, 0, &hostzeroisbroadcast, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_HOSTZEROBROADCAST, CTL_EOL);
#if NGIF > 0
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "gifttl",
                       SYSCTL_DESCR("Default TTL for a gif tunnel datagram"),
                       NULL, 0, &ip_gif_ttl, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_GIF_TTL, CTL_EOL);
#endif /* NGIF */
#ifndef IPNOPRIVPORTS
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "lowportmin",
                       SYSCTL_DESCR("Lowest privileged ephemeral port number "
                                    "to assign"),
                       sysctl_net_inet_ip_ports, 0, &lowportmin, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_LOWPORTMIN, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "lowportmax",
                       SYSCTL_DESCR("Highest privileged ephemeral port number "
                                    "to assign"),
                       sysctl_net_inet_ip_ports, 0, &lowportmax, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_LOWPORTMAX, CTL_EOL);
#endif /* IPNOPRIVPORTS */
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "maxfragpackets",
                       SYSCTL_DESCR("Maximum number of fragments to retain for "
                                    "possible reassembly"),
                       NULL, 0, &ip_maxfragpackets, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_MAXFRAGPACKETS, CTL_EOL);
#if NGRE > 0
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "grettl",
                       SYSCTL_DESCR("Default TTL for a gre tunnel datagram"),
                       NULL, 0, &ip_gre_ttl, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_GRE_TTL, CTL_EOL);
#endif /* NGRE */
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "checkinterface",
                       SYSCTL_DESCR("Enable receive side of Strong ES model "
                                    "from RFC1122"),
                       NULL, 0, &ip_checkinterface, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_CHECKINTERFACE, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "random_id",
                       SYSCTL_DESCR("Assign random ip_id values"),
                       NULL, 0, &ip_do_randomid, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_RANDOMID, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "do_loopback_cksum",
                       SYSCTL_DESCR("Perform IP checksum on loopback"),
                       NULL, 0, &ip_do_loopback_cksum, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_LOOPBACKCKSUM, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_STRUCT, "stats",
                       SYSCTL_DESCR("IP statistics"),
                       sysctl_net_inet_ip_stats, 0, NULL, 0,
                       CTL_NET, PF_INET, IPPROTO_IP, IPCTL_STATS,
                       CTL_EOL);
}

void
ip_statinc(u_int stat)
{

        KASSERT(stat < IP_NSTATS);
        IP_STATINC(stat);
}