/*      $NetBSD: ip_input.c,v 1.407 2026/05/29 02:52:06 ozaki-r 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 1.407 2026/05/29 02:52:06 ozaki-r Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#include "opt_gateway.h"
#include "opt_ipsec.h"
#include "opt_mrouting.h"
#include "opt_mbuftrace.h"
#include "opt_inet_csum.h"
#include "opt_net_mpsafe.h"
#endif

#include "arp.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/cpu.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/if_types.h>
#include <net/route.h>
#include <net/pktqueue.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
#include <netinet/portalgo.h>

#ifdef IPSEC
#include <netipsec/ipsec.h>
#endif

#ifndef IPFORWARDING
#ifdef GATEWAY
#define IPFORWARDING    1       /* forward IP packets not for us */
#else
#define IPFORWARDING    0       /* don't forward IP packets not for us */
#endif
#endif

#define IPMTUDISCTIMEOUT (10 * 60)      /* as per RFC 1191 */

int ipforwarding = IPFORWARDING;
int ipsendredirects = 1;
int ip_defttl = IPDEFTTL;
int ip_forwsrcrt = 0;
int ip_directedbcast = 0;
int ip_allowsrcrt = 0;
int ip_mtudisc = 1;
int ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
int ip_do_randomid = 1;

/*
 * 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 NAT
 * 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.
 */
static int              ip_checkinterface       __read_mostly = 0;

struct rttimer_queue *ip_mtudisc_timeout_q = NULL;

pktqueue_t *            ip_pktq                 __read_mostly;
pfil_head_t *           inet_pfil_hook          __read_mostly;
percpu_t *              ipstat_percpu           __read_mostly;

static percpu_t         *ipforward_rt_percpu    __cacheline_aligned;

uint16_t ip_id;

#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 */

/*
 * Used 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.
 */
struct ip_srcrt {
        int             isr_nhops;                 /* number of hops */
        struct in_addr  isr_dst;                   /* final destination */
        char            isr_nop;                   /* one NOP to align */
        char            isr_hdr[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN & OFFSET */
        struct in_addr  isr_routes[MAX_IPOPTLEN/sizeof(struct in_addr)];
};

static int ip_drainwanted;

static void save_rte(struct mbuf *, 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             ipintr(void *);
static void             ip_input(struct mbuf *, struct ifnet *);
static void             ip_forward(struct mbuf *, int, struct ifnet *);
static bool             ip_dooptions(struct mbuf *);
static int              ip_rtaddr(struct in_addr, struct in_addr *);
static void             sysctl_net_inet_ip_setup(struct sysctllog **);

static struct in_ifaddr *ip_match_our_address(struct ifnet *, struct ip *,
                            int *);
static struct in_ifaddr *ip_match_our_address_broadcast(struct ifnet *,
                            struct ip *);

#ifdef NET_MPSAFE
#define SOFTNET_LOCK()          mutex_enter(softnet_lock)
#define SOFTNET_UNLOCK()        mutex_exit(softnet_lock)
#else
#define SOFTNET_LOCK()          KASSERT(mutex_owned(softnet_lock))
#define SOFTNET_UNLOCK()        KASSERT(mutex_owned(softnet_lock))
#endif

/*
 * 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;

        ip_pktq = pktq_create(IFQ_MAXLEN, ipintr, NULL);
        KASSERT(ip_pktq != NULL);

        in_init();
        sysctl_net_inet_ip_setup(NULL);

        pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
        KASSERT(pr != NULL);

        for (u_int 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;

        ip_reass_init();

        ip_id = time_uptime & 0xfffff;

#ifdef GATEWAY
        ipflow_init();
#endif

        /* Register our Packet Filter hook. */
        inet_pfil_hook = pfil_head_create(PFIL_TYPE_AF, (void *)AF_INET);
        KASSERT(inet_pfil_hook != NULL);

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

        ipstat_percpu = percpu_alloc(sizeof(uint64_t) * IP_NSTATS);
        ipforward_rt_percpu = rtcache_percpu_alloc();
        ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout);
}

static struct in_ifaddr *
ip_match_our_address(struct ifnet *ifp, struct ip *ip, int *downmatch)
{
        struct in_ifaddr *ia = NULL;
        int checkif;

        /*
         * 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 - We need to add a per ifaddr flag for this so that
         * we get finer grain control.
         */
        checkif = ip_checkinterface && (ipforwarding == 0) &&
            (ifp->if_flags & IFF_LOOPBACK) == 0;

        IN_ADDRHASH_READER_FOREACH(ia, ip->ip_dst.s_addr) {
                if (in_hosteq(ia->ia_addr.sin_addr, ip->ip_dst)) {
                        if (ia->ia4_flags & IN_IFF_NOTREADY)
                                continue;
                        if (checkif && ia->ia_ifp != ifp)
                                continue;
                        if ((ia->ia_ifp->if_flags & IFF_UP) == 0) {
                                (*downmatch)++;
                                continue;
                        }
                        if (ia->ia4_flags & IN_IFF_DETACHED &&
                            (ifp->if_flags & IFF_LOOPBACK) == 0)
                                continue;
                        break;
                }
        }

        return ia;
}

static struct in_ifaddr *
ip_match_our_address_broadcast(struct ifnet *ifp, struct ip *ip)
{
        struct in_ifaddr *ia = NULL;
        struct ifaddr *ifa;

        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != AF_INET)
                        continue;
                ia = ifatoia(ifa);
                if (ia->ia4_flags & IN_IFF_NOTREADY)
                        continue;
                if (ia->ia4_flags & IN_IFF_DETACHED &&
                    (ifp->if_flags & IFF_LOOPBACK) == 0)
                        continue;
                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 matched;
                /*
                 * An interface with IP address zero accepts
                 * all packets that arrive on that interface.
                 */
                if (in_nullhost(ia->ia_addr.sin_addr))
                        goto matched;
        }
        ia = NULL;

matched:
        return ia;
}

/*
 * IP software interrupt routine.
 */
static void
ipintr(void *arg __unused)
{
        struct mbuf *m;

        KASSERT(cpu_softintr_p());

        SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();
        while ((m = pktq_dequeue(ip_pktq)) != NULL) {
                struct ifnet *ifp;
                struct psref psref;

                ifp = m_get_rcvif_psref(m, &psref);
                if (__predict_false(ifp == NULL)) {
                        IP_STATINC(IP_STAT_IFDROP);
                        m_freem(m);
                        continue;
                }

                ip_input(m, ifp);

                m_put_rcvif_psref(ifp, &psref);
        }
        SOFTNET_KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
}

/*
 * IP input routine.  Checksum and byte swap header.  If fragmented
 * try to reassemble.  Process options.  Pass to next level.
 */
static void
ip_input(struct mbuf *m, struct ifnet *ifp)
{
        struct ip *ip = NULL;
        struct in_ifaddr *ia = NULL;
        int hlen = 0, len;
        int downmatch;
        int srcrt = 0;
        int s;

        KASSERTMSG(cpu_softintr_p(), "ip_input: not in the software "
            "interrupt handler; synchronization assumptions violated");

        MCLAIM(m, &ip_rx_mowner);
        KASSERT((m->m_flags & M_PKTHDR) != 0);

        /*
         * If no IP addresses have been set yet but the interfaces
         * are receiving, can't do anything with incoming packets yet.
         * Note: we pre-check without locks held.
         */
        if (IN_ADDRLIST_READER_EMPTY()) {
                IP_STATINC(IP_STAT_IFDROP);
                goto out;
        }

        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 (M_GET_ALIGNED_HDR(&m, struct ip, true) != 0) {
                /* XXXJRT new stat, please */
                IP_STATINC(IP_STAT_TOOSMALL);
                goto out;
        }
        ip = mtod(m, struct ip *);
        if (ip->ip_v != IPVERSION) {
                IP_STATINC(IP_STAT_BADVERS);
                goto out;
        }
        hlen = ip->ip_hl << 2;
        if (hlen < sizeof(struct ip)) { /* minimum header length */
                IP_STATINC(IP_STAT_BADHLEN);
                goto out;
        }
        if (hlen > m->m_len) {
                if ((m = m_pullup(m, hlen)) == NULL) {
                        IP_STATINC(IP_STAT_BADHLEN);
                        goto out;
                }
                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 out;
        }

        /* 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 ((ifp->if_flags & IFF_LOOPBACK) == 0) {
                        IP_STATINC(IP_STAT_BADADDR);
                        goto out;
                }
        }

        switch (m->m_pkthdr.csum_flags &
                ((ifp->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);
                IP_STATINC(IP_STAT_BADSUM);
                goto out;

        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(!(ifp->if_flags & IFF_LOOPBACK) ||
                    ip_do_loopback_cksum)) {
                        INET_CSUM_COUNTER_INCR(&ip_swcsum);
                        if (in_cksum(m, hlen) != 0) {
                                IP_STATINC(IP_STAT_BADSUM);
                                goto out;
                        }
                }
                break;
        }

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

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

        /*
         * Check that the amount of data in the buffers is at least as 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 out;
        }
        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);
        }

        /*
         * Assume that we can create a fast-forward IP flow entry
         * based on this packet.
         */
        m->m_flags |= M_CANFASTFWD;

        /*
         * 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.
         *
         * Don't call hooks if the packet has already been processed by
         * IPsec (encapsulated, tunnel mode).
         */
#if defined(IPSEC)
        if (!ipsec_used || !ipsec_skip_pfil(m))
#else
        if (1)
#endif
        {
                struct in_addr odst = ip->ip_dst;
                bool freed;

                freed = pfil_run_hooks(inet_pfil_hook, &m, ifp, PFIL_IN) != 0;
                if (freed || m == NULL) {
                        m = NULL;
                        IP_STATINC(IP_STAT_PFILDROP_IN);
                        goto out;
                }
                if (__predict_false(m->m_len < sizeof(struct ip))) {
                        if ((m = m_pullup(m, sizeof(struct ip))) == NULL) {
                                IP_STATINC(IP_STAT_TOOSMALL);
                                goto out;
                        }
                }
                ip = mtod(m, struct ip *);
                hlen = ip->ip_hl << 2;
                if (hlen < sizeof(struct ip)) { /* minimum header length */
                        IP_STATINC(IP_STAT_BADHLEN);
                        goto out;
                }
                if (hlen > m->m_len) {
                        if ((m = m_pullup(m, hlen)) == NULL) {
                                IP_STATINC(IP_STAT_BADHLEN);
                                goto out;
                        }
                        ip = mtod(m, struct ip *);
                }

                /*
                 * 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 influenced 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);
        }

#ifdef ALTQ
        /* XXX Temporary until ALTQ is changed to use a pfil hook */
        if (altq_input) {
                SOFTNET_LOCK();
                if ((*altq_input)(m, AF_INET) == 0) {
                        /* Packet dropped by traffic conditioner. */
                        SOFTNET_UNLOCK();
                        m = NULL;
                        goto out;
                }
                SOFTNET_UNLOCK();
        }
#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).
         */
        if (hlen > sizeof(struct ip) && ip_dooptions(m)) {
                m = NULL;
                goto out;
        }

        /*
         * 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
         * or IN_IFF_NOTREADY addresses as not mine.
         */
        downmatch = 0;
        s = pserialize_read_enter();
        ia = ip_match_our_address(ifp, ip, &downmatch);
        if (ia != NULL) {
                pserialize_read_exit(s);
                goto ours;
        }

        if (ifp->if_flags & IFF_BROADCAST) {
                ia = ip_match_our_address_broadcast(ifp, ip);
                if (ia != NULL) {
                        pserialize_read_exit(s);
                        goto ours;
                }
        }
        pserialize_read_exit(s);

        if (IN_MULTICAST(ip->ip_dst.s_addr)) {
#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().)
                         */
                        SOFTNET_LOCK();
                        if (ip_mforward(m, ifp) != 0) {
                                SOFTNET_UNLOCK();
                                IP_STATINC(IP_STAT_CANTFORWARD);
                                goto out;
                        }
                        SOFTNET_UNLOCK();

                        /*
                         * 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.
                 */
                if (!in_multi_group(ip->ip_dst, ifp, 0)) {
                        IP_STATINC(IP_STAT_CANTFORWARD);
                        goto out;
                }
                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);
                return;
        }

        /*
         * 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
        /* Check the security policy (SP) for the packet */
        if (ipsec_used) {
                if (ipsec_ip_input_checkpolicy(m, true) != 0) {
                        IP_STATINC(IP_STAT_IPSECDROP_IN);
                        goto out;
                }
        }
#endif
        ip_forward(m, srcrt, ifp);
        return;

ours:
        /*
         * If offset or IP_MF are set, must reassemble.
         */
        if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
                /*
                 * Pass to IP reassembly mechanism.
                 */
                if (ip_reass_packet(&m) != 0) {
                        /* Failed; invalid fragment(s) or packet. */
                        goto out;
                }
                if (m == NULL) {
                        /* More fragments should come; silently return. */
                        goto out;
                }
                /*
                 * Reassembly is done, we have the final packet.
                 * Update cached data in local variable(s).
                 */
                ip = mtod(m, struct ip *);
                hlen = ip->ip_hl << 2;
        }

        M_VERIFY_PACKET(m);

#ifdef 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 (ipsec_used &&
            (inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
                if (ipsec_ip_input_checkpolicy(m, false) != 0) {
                        IP_STATINC(IP_STAT_IPSECDROP_IN);
                        goto out;
                }
        }
#endif

        /*
         * Switch out to protocol's input routine.
         */
#if IFA_STATS
        if (ia) {
                struct in_ifaddr *_ia;
                /*
                 * Keep a reference from ip_match_our_address with psref
                 * is expensive, so explore ia here again.
                 */
                s = pserialize_read_enter();
                _ia = in_get_ia(ip->ip_dst);
                _ia->ia_ifa.ifa_data.ifad_inbytes += ntohs(ip->ip_len);
                pserialize_read_exit(s);
        }
#endif
        IP_STATINC(IP_STAT_DELIVERED);

        const int off = hlen, nh = ip->ip_p;

        (*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
        return;

out:
        m_freem(m);
}

/*
 * IP timer processing.
 */
void
ip_slowtimo(void)
{

        SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();

        ip_reass_slowtimo();

        SOFTNET_KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
}

/*
 * IP drain processing.
 */
void
ip_drain(void)
{

        KERNEL_LOCK(1, NULL);
        ip_reass_drain();
        KERNEL_UNLOCK_ONE(NULL);
}

/*
 * ip_dooptions: perform option processing on a datagram, possibly discarding
 * it if bad options are encountered, or forwarding it if source-routed.
 *
 * => Returns true if packet has been forwarded/freed.
 * => Returns false if the packet should be processed further.
 */
static bool
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;
        int srr_present, rr_present, ts_present;
        struct in_addr dst;
        n_time ntime;
        struct ifaddr *ifa = NULL;
        int s;

        srr_present = 0;
        rr_present = 0;
        ts_present = 0;

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

                        if (ip_allowsrcrt == 0) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_NET_PROHIB;
                                goto bad;
                        }
                        if (srr_present++) {
                                code = &cp[IPOPT_OPTVAL] - (u_char *)ip;
                                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;

                        s = pserialize_read_enter();
                        ifa = ifa_ifwithaddr(sintosa(&ipaddr));
                        if (ifa == NULL) {
                                pserialize_read_exit(s);
                                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;
                        }
                        pserialize_read_exit(s);

                        off--;                  /* 0 origin */
                        if ((off + sizeof(struct in_addr)) > optlen) {
                                /*
                                 * End of source route.  Should be for us.
                                 */
                                save_rte(m, cp, ip->ip_src);
                                break;
                        }
                        /*
                         * locate outgoing interface
                         */
                        memcpy((void *)&ipaddr.sin_addr, (void *)(cp + off),
                            sizeof(ipaddr.sin_addr));
                        int error = -1;
                        if (opt == IPOPT_SSRR) {
                                s = pserialize_read_enter();
                                ifa = ifa_ifwithladdr(sintosa(&ipaddr));
                                if (ifa != NULL) {
                                        ia = ifatoia(ifa);
                                        memcpy(cp + off, &ia->ia_addr.sin_addr,
                                            sizeof(struct in_addr));
                                        error = 0;
                                }
                                pserialize_read_exit(s);
                        } else {
                                struct in_addr addr;
                                error = ip_rtaddr(ipaddr.sin_addr, &addr);
                                if (error == 0)
                                        memcpy(cp + off, &addr, sizeof(addr));
                        }
                        if (error != 0) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_SRCFAIL;
                                goto bad;
                        }
                        ip->ip_dst = ipaddr.sin_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: {
                        struct sockaddr_in ipaddr = {
                            .sin_len = sizeof(ipaddr),
                            .sin_family = AF_INET,
                        };

                        if (rr_present++) {
                                code = &cp[IPOPT_OPTVAL] - (u_char *)ip;
                                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;
                        }
                        /*
                         * 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).
                         */
                        s = pserialize_read_enter();
                        ifa = ifa_ifwithaddr(sintosa(&ipaddr));
                        if (ifa != NULL) {
                                ia = ifatoia(ifa);
                                memcpy(cp + off, &ia->ia_addr.sin_addr,
                                    sizeof(struct in_addr));
                                pserialize_read_exit(s);
                        } else {
                                struct in_addr addr;
                                int error;
                                pserialize_read_exit(s);

                                error = ip_rtaddr(ipaddr.sin_addr, &addr);
                                if (error != 0) {
                                        type = ICMP_UNREACH;
                                        code = ICMP_UNREACH_HOST;
                                        goto bad;
                                }
                                memcpy(cp + off, &addr, sizeof(addr));
                        }
                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                        break;
                    }

                case IPOPT_TS:
                        code = cp - (u_char *)ip;
                        ipt = (struct ip_timestamp *)cp;
                        if (ts_present++) {
                                code = &cp[IPOPT_OPTVAL] - (u_char *)ip;
                                goto bad;
                        }
                        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: {
                                struct ifnet *rcvif;
                                int _s, _ss;
                                struct sockaddr_in ipaddr = {
                                    .sin_len = sizeof(ipaddr),
                                    .sin_family = AF_INET,
                                };

                                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;
                                _ss = pserialize_read_enter();
                                rcvif = m_get_rcvif(m, &_s);
                                if (__predict_true(rcvif != NULL)) {
                                        ifa = ifaof_ifpforaddr(sintosa(&ipaddr),
                                            rcvif);
                                }
                                m_put_rcvif(rcvif, &_s);
                                if (ifa == NULL) {
                                        pserialize_read_exit(_ss);
                                        break;
                                }
                                ia = ifatoia(ifa);
                                memcpy(cp0, &ia->ia_addr.sin_addr,
                                    sizeof(struct in_addr));
                                pserialize_read_exit(_ss);
                                ipt->ipt_ptr += sizeof(struct in_addr);
                                break;
                        }

                        case IPOPT_TS_PRESPEC: {
                                struct sockaddr_in ipaddr = {
                                    .sin_len = sizeof(ipaddr),
                                    .sin_family = AF_INET,
                                };

                                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));
                                s = pserialize_read_enter();
                                ifa = ifa_ifwithaddr(sintosa(&ipaddr));
                                if (ifa == NULL) {
                                        pserialize_read_exit(s);
                                        continue;
                                }
                                pserialize_read_exit(s);
                                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) {
                struct ifnet *rcvif;
                struct psref _psref;

                if (ip_forwsrcrt == 0) {
                        type = ICMP_UNREACH;
                        code = ICMP_UNREACH_SRCFAIL;
                        goto bad;
                }

                rcvif = m_get_rcvif_psref(m, &_psref);
                if (__predict_false(rcvif == NULL)) {
                        type = ICMP_UNREACH;
                        code = ICMP_UNREACH_HOST;
                        goto bad;
                }
                ip_forward(m, 1, rcvif);
                m_put_rcvif_psref(rcvif, &_psref);
                return true;
        }
        return false;
bad:
        icmp_error(m, type, code, 0, 0);
        IP_STATINC(IP_STAT_BADOPTIONS);
        return true;
}

/*
 * ip_rtaddr: given address of next destination (final or next hop),
 * return internet address of interface to be used to get there.
 */
static int
ip_rtaddr(struct in_addr dst, struct in_addr *ret)
{
        struct rtentry *rt;
        union {
                struct sockaddr         dst;
                struct sockaddr_in      dst4;
        } u;
        struct route *ro;
        struct in_ifaddr *ia;

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

        ro = rtcache_percpu_getref(ipforward_rt_percpu);
        rt = rtcache_lookup(ro, &u.dst);
        if (rt == NULL) {
                rtcache_percpu_putref(ipforward_rt_percpu);
                return -1;
        }

        ia = ifatoia(rt->rt_ifa);
        *ret = ia->ia_addr.sin_addr;
        rtcache_unref(rt, ro);
        rtcache_percpu_putref(ipforward_rt_percpu);

        return 0;
}

/*
 * save_rte: save incoming source route for use in replies, to be picked
 * up later by ip_srcroute if the receiver is interested.
 */
static void
save_rte(struct mbuf *m, u_char *option, struct in_addr dst)
{
        struct ip_srcrt *isr;
        struct m_tag *mtag;
        unsigned olen;

        olen = option[IPOPT_OLEN];
        if (olen > sizeof(isr->isr_hdr) + sizeof(isr->isr_routes))
                return;

        mtag = m_tag_get(PACKET_TAG_SRCROUTE, sizeof(*isr), M_NOWAIT);
        if (mtag == NULL)
                return;
        isr = (struct ip_srcrt *)(mtag + 1);

        memcpy(isr->isr_hdr, option, olen);
        isr->isr_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
        isr->isr_dst = dst;
        m_tag_prepend(m, mtag);
}

/*
 * 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(struct mbuf *m0)
{
        struct in_addr *p, *q;
        struct mbuf *m;
        struct ip_srcrt *isr;
        struct m_tag *mtag;

        mtag = m_tag_find(m0, PACKET_TAG_SRCROUTE);
        if (mtag == NULL)
                return NULL;
        isr = (struct ip_srcrt *)(mtag + 1);

        if (isr->isr_nhops == 0)
                return NULL;

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

        MCLAIM(m, &inetdomain.dom_mowner);
#define OPTSIZ  (sizeof(isr->isr_nop) + sizeof(isr->isr_hdr))

        /* length is (nhops+1)*sizeof(addr) + sizeof(nop + header) */
        m->m_len = (isr->isr_nhops + 1) * sizeof(struct in_addr) + OPTSIZ;

        /*
         * First save first hop for return route
         */
        p = &(isr->isr_routes[isr->isr_nhops - 1]);
        *(mtod(m, struct in_addr *)) = *p--;

        /*
         * Copy option fields and padding (nop) to mbuf.
         */
        isr->isr_nop = IPOPT_NOP;
        isr->isr_hdr[IPOPT_OFFSET] = IPOPT_MINOFF;
        memmove(mtod(m, char *) + sizeof(struct in_addr), &isr->isr_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 >= isr->isr_routes) {
                *q++ = *p--;
        }
        /*
         * Last hop goes to final destination.
         */
        *q = isr->isr_dst;
        m_tag_delete(m0, mtag);
        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,
};

void
ip_fasttimo(void)
{
        if (ip_drainwanted) {
                ip_drain();
                ip_drainwanted = 0;
        }
}

void
ip_drainstub(void)
{
        ip_drainwanted = 1;
}

/*
 * 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.
 */
static void
ip_forward(struct mbuf *m, int srcrt, struct ifnet *rcvif)
{
        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;
        net_stat_ref_t ips;
        struct route *ro;

        KASSERTMSG(cpu_softintr_p(), "ip_forward: not in the software "
            "interrupt handler; synchronization assumptions violated");

        /*
         * 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;
        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) {
                IP_STATINC(IP_STAT_TIMXCEED);
                icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
                return;
        }

        sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);

        ro = rtcache_percpu_getref(ipforward_rt_percpu);
        rt = rtcache_lookup(ro, &u.dst);
        if (rt == NULL) {
                rtcache_percpu_putref(ipforward_rt_percpu);
                IP_STATINC(IP_STAT_NOROUTE);
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, dest, 0);
                return;
        }
#ifdef NET_MPSAFE
        /*
         * XXX workaround an inconsistency issue between address and route on
         * address initialization to avoid packet looping.  See doc/TODO.smpnet.
         */
        if (__predict_false(rt->rt_ifp->if_type == IFT_LOOP)) {
                rtcache_unref(rt, ro);
                rtcache_percpu_putref(ipforward_rt_percpu);
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
                IP_STATINC(IP_STAT_CANTFORWARD);
                return;
        }
#endif

        /*
         * 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 == rcvif &&
            (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
            !in_nullhost(satocsin(rt_getkey(rt))->sin_addr) &&
            ipsendredirects && !srcrt) {
                if ((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;
                }
        }
        rtcache_unref(rt, ro);

        error = ip_output(m, NULL, ro,
            (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)),
            NULL, NULL);

        if (error) {
                IP_STATINC(IP_STAT_CANTFORWARD);
                goto error;
        }

        ips = IP_STAT_GETREF();
        _NET_STATINC_REF(ips, IP_STAT_FORWARD);

        if (type) {
                _NET_STATINC_REF(ips, IP_STAT_REDIRECTSENT);
                IP_STAT_PUTREF();
                goto redirect;
        }

        IP_STAT_PUTREF();
        if (mcopy) {
#ifdef GATEWAY
                if (mcopy->m_flags & M_CANFASTFWD)
                        ipflow_create(ro, mcopy);
#endif
                m_freem(mcopy);
        }

        rtcache_percpu_putref(ipforward_rt_percpu);
        return;

redirect:
error:
        if (mcopy == NULL) {
                rtcache_percpu_putref(ipforward_rt_percpu);
                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(ro)) != NULL) {
                        destmtu = rt->rt_ifp->if_mtu;
                        rtcache_unref(rt, ro);
                }
#ifdef IPSEC
                if (ipsec_used)
                        ipsec_mtu(mcopy, &destmtu);
#endif
                IP_STATINC(IP_STAT_CANTFRAG);
                break;

        case ENOBUFS:
                /*
                 * Do not generate ICMP_SOURCEQUENCH as required in RFC 1812,
                 * Requirements for IP Version 4 Routers.  Source quench can
                 * be a big problem under DoS attacks or if the underlying
                 * interface is rate-limited.
                 */
                m_freem(mcopy);
                rtcache_percpu_putref(ipforward_rt_percpu);
                return;
        }
        icmp_error(mcopy, type, code, dest, destmtu);
        rtcache_percpu_putref(ipforward_rt_percpu);
}

void
ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
    struct mbuf *m)
{
        struct socket *so = inp->inp_socket;
        int inpflags = inp->inp_flags;

        if (SOOPT_TIMESTAMP(so->so_options))
                mp = sbsavetimestamp(so->so_options, mp);

        if (inpflags & INP_RECVDSTADDR) {
                *mp = sbcreatecontrol(&ip->ip_dst,
                    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }

        if (inpflags & INP_RECVTTL) {
                *mp = sbcreatecontrol(&ip->ip_ttl,
                    sizeof(uint8_t), IP_RECVTTL, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }

        struct psref psref;
        ifnet_t *ifp = m_get_rcvif_psref(m, &psref);
        if (__predict_false(ifp == NULL)) {
#ifdef DIAGNOSTIC
                printf("%s: missing receive interface\n", __func__);
#endif
                return; /* XXX should report error? */
        }

        if (inpflags & INP_RECVPKTINFO) {
                struct in_pktinfo ipi;
                ipi.ipi_addr = ip->ip_dst;
                ipi.ipi_ifindex = ifp->if_index;
                *mp = sbcreatecontrol(&ipi,
                    sizeof(ipi), IP_PKTINFO, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
        if (inpflags & INP_RECVIF) {
                struct sockaddr_dl sdl;

                sockaddr_dl_init(&sdl, sizeof(sdl), ifp->if_index, 0, NULL, 0,
                    NULL, 0);
                *mp = sbcreatecontrol(&sdl, sdl.sdl_len, IP_RECVIF, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
        m_put_rcvif_psref(ifp, &psref);
}

/*
 * 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;

        icmp_mtudisc_lock();

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

        ip_mtudisc_timeout = tmp;
        rt_timer_queue_change(ip_mtudisc_timeout_q, ip_mtudisc_timeout);
        error = 0;
out:
        icmp_mtudisc_unlock();
        return error;
}

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)
{
        const struct sysctlnode *ip_node;

        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, &ip_node,
                       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);
        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, "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, (void *)&ip_mtudisc_timeout, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_MTUDISCTIMEOUT, CTL_EOL);
#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 */
#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);

        pktq_sysctl_setup(ip_pktq, clog, ip_node, IPCTL_IFQ);

        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);
#if NARP
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "dad_count",
                       SYSCTL_DESCR("Number of Duplicate Address Detection "
                                    "probes to send"),
                       NULL, 0, &ip_dad_count, 0,
                       CTL_NET, PF_INET, IPPROTO_IP,
                       IPCTL_DAD_COUNT, CTL_EOL);
#endif

        /* anonportalgo RFC6056 subtree */
        const struct sysctlnode *portalgo_node;
        sysctl_createv(clog, 0, NULL, &portalgo_node,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "anonportalgo",
                       SYSCTL_DESCR("Anonymous Port Algorithm Selection (RFC 6056)"),
                       NULL, 0, NULL, 0,
                       CTL_NET, PF_INET, IPPROTO_IP, CTL_CREATE, CTL_EOL);
        sysctl_createv(clog, 0, &portalgo_node, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_STRING, "available",
                       SYSCTL_DESCR("available algorithms"),
                       sysctl_portalgo_available, 0, NULL, PORTALGO_MAXLEN,
                       CTL_CREATE, CTL_EOL);
        sysctl_createv(clog, 0, &portalgo_node, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_STRING, "selected",
                       SYSCTL_DESCR("selected algorithm"),
                       sysctl_portalgo_selected4, 0, NULL, PORTALGO_MAXLEN,
                       CTL_CREATE, CTL_EOL);
        sysctl_createv(clog, 0, &portalgo_node, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_STRUCT, "reserve",
                       SYSCTL_DESCR("bitmap of reserved ports"),
                       sysctl_portalgo_reserve4, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL);
}

void
ip_statinc(u_int stat)
{

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