/*      $OpenBSD: ip_input.c,v 1.426 2025/11/12 10:00:27 hshoexer Exp $ */
/*      $NetBSD: ip_input.c,v 1.30 1996/03/16 23:53:58 christos Exp $   */

/*
 * 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 "pf.h"
#include "carp.h"
#include "ether.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/mutex.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/pool.h>
#include <sys/task.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/netisr.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/if_ether.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <net/if_types.h>

#ifdef INET6
#include <netinet6/ip6_var.h>
#endif

#if NPF > 0
#include <net/pfvar.h>
#endif

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

#ifdef IPSEC
#include <netinet/ip_ipsp.h>
#endif /* IPSEC */

#if NCARP > 0
#include <netinet/ip_carp.h>
#endif

/*
 * Locks used to protect global variables in this file:
 *      I       immutable after creation
 *      N       net lock
 *      Q       ipq_mutex
 *      a       atomic operations
 */

/* values controllable via sysctl */
int     ip_forwarding = 0;                      /* [a] */
int     ipmforwarding = 0;                      /* [a] */
int     ipmultipath = 0;                        /* [a] */
int     ip_sendredirects = 1;                   /* [a] */
int     ip_dosourceroute = 0;                   /* [a] */
int     ip_defttl = IPDEFTTL;                   /* [a] */
int     ip_mtudisc = 1;                         /* [a] */
int     ip_mtudisc_timeout = IPMTUDISCTIMEOUT;  /* [a] */
int     ip_directedbcast = 0;                   /* [a] */

struct mutex    ipq_mutex = MUTEX_INITIALIZER(IPL_SOFTNET);

/* IP reassembly queue */
LIST_HEAD(, ipq) ipq;                           /* [Q] */

/* Keep track of memory used for reassembly */
int     ip_maxqueue = 300;                      /* [a] */
int     ip_frags = 0;                           /* [Q] */

#ifndef SMALL_KERNEL
const struct sysctl_bounded_args ipctl_vars[] = {
        { IPCTL_FORWARDING, &ip_forwarding, 0, 2 },
        { IPCTL_SENDREDIRECTS, &ip_sendredirects, 0, 1 },
        { IPCTL_DIRECTEDBCAST, &ip_directedbcast, 0, 1 },
#ifdef MROUTING
        { IPCTL_MRTPROTO, &ip_mrtproto, SYSCTL_INT_READONLY },
#endif
        { IPCTL_DEFTTL, &ip_defttl, 0, 255 },
        { IPCTL_IPPORT_FIRSTAUTO, &ipport_firstauto, 0, 65535 },
        { IPCTL_IPPORT_LASTAUTO, &ipport_lastauto, 0, 65535 },
        { IPCTL_IPPORT_HIFIRSTAUTO, &ipport_hifirstauto, 0, 65535 },
        { IPCTL_IPPORT_HILASTAUTO, &ipport_hilastauto, 0, 65535 },
        { IPCTL_IPPORT_MAXQUEUE, &ip_maxqueue, 0, 10000 },
        { IPCTL_MFORWARDING, &ipmforwarding, 0, 1 },
        { IPCTL_ARPTIMEOUT, &arpt_keep, 0, INT_MAX },
        { IPCTL_ARPDOWN, &arpt_down, 0, INT_MAX },
};
#endif /* SMALL_KERNEL */

struct niqueue ipintrq = NIQUEUE_INITIALIZER(IPQ_MAXLEN, NETISR_IP);

struct pool ipqent_pool;
struct pool ipq_pool;

struct cpumem *ipcounters;

int ip_sysctl_ipstat(void *, size_t *, void *);

static struct mbuf_queue        ipsend_mq;
static struct mbuf_queue        ipsendraw_mq;

extern struct niqueue           arpinq;

int     ip_ours(struct mbuf **, int *, int, int, struct netstack *);
int     ip_ours_enqueue(struct mbuf **mp, int *offp, int nxt);
int     ip_dooptions(struct mbuf *, struct ifnet *, int);
int     in_ouraddr(struct mbuf *, struct ifnet *, struct route *, int);

int             ip_fragcheck(struct mbuf **, int *);
struct mbuf *   ip_reass(struct ipqent *, struct ipq *);
void            ip_freef(struct ipq *);
void            ip_flush(int);

static void ip_send_dispatch(void *);
static void ip_sendraw_dispatch(void *);
static struct task ipsend_task = TASK_INITIALIZER(ip_send_dispatch, &ipsend_mq);
static struct task ipsendraw_task =
        TASK_INITIALIZER(ip_sendraw_dispatch, &ipsendraw_mq);

/*
 * 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)];
};

void save_rte(struct mbuf *, u_char *, struct in_addr);

/*
 * 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;
        const u_int16_t defbaddynamicports_tcp[] = DEFBADDYNAMICPORTS_TCP;
        const u_int16_t defbaddynamicports_udp[] = DEFBADDYNAMICPORTS_UDP;
        const u_int16_t defrootonlyports_tcp[] = DEFROOTONLYPORTS_TCP;
        const u_int16_t defrootonlyports_udp[] = DEFROOTONLYPORTS_UDP;

        ipcounters = counters_alloc(ips_ncounters);

        pool_init(&ipqent_pool, sizeof(struct ipqent), 0,
            IPL_SOFTNET, 0, "ipqe",  NULL);
        pool_init(&ipq_pool, sizeof(struct ipq), 0,
            IPL_SOFTNET, 0, "ipq", NULL);

        pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
        if (pr == NULL)
                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 &&
                    pr->pr_protocol < IPPROTO_MAX)
                        ip_protox[pr->pr_protocol] = pr - inetsw;
        LIST_INIT(&ipq);

        /* Fill in list of ports not to allocate dynamically. */
        memset(&baddynamicports, 0, sizeof(baddynamicports));
        for (i = 0; defbaddynamicports_tcp[i] != 0; i++)
                DP_SET(baddynamicports.tcp, defbaddynamicports_tcp[i]);
        for (i = 0; defbaddynamicports_udp[i] != 0; i++)
                DP_SET(baddynamicports.udp, defbaddynamicports_udp[i]);

        /* Fill in list of ports only root can bind to. */
        memset(&rootonlyports, 0, sizeof(rootonlyports));
        for (i = 0; defrootonlyports_tcp[i] != 0; i++)
                DP_SET(rootonlyports.tcp, defrootonlyports_tcp[i]);
        for (i = 0; defrootonlyports_udp[i] != 0; i++)
                DP_SET(rootonlyports.udp, defrootonlyports_udp[i]);

        mq_init(&ipsend_mq, 64, IPL_SOFTNET);
        mq_init(&ipsendraw_mq, 64, IPL_SOFTNET);

#if NETHER > 0
        arpinit();
#endif
#ifdef IPSEC
        ipsec_init();
#endif
#ifdef MROUTING
        mrt_init();
#endif
}

/*
 * Enqueue packet for local delivery.  Queuing is used as a boundary
 * between the network layer (input/forward path) running with
 * NET_LOCK_SHARED() and the transport layer needing it exclusively.
 */
int
ip_ours(struct mbuf **mp, int *offp, int nxt, int af, struct netstack *ns)
{
        nxt = ip_fragcheck(mp, offp);
        if (nxt == IPPROTO_DONE)
                return IPPROTO_DONE;

        /* We are already in a IPv4/IPv6 local deliver loop. */
        if (af != AF_UNSPEC)
                return nxt;

        nxt = ip_deliver(mp, offp, nxt, AF_INET, 1, ns);
        if (nxt == IPPROTO_DONE)
                return IPPROTO_DONE;

        return ip_ours_enqueue(mp, offp, nxt);
}

int
ip_ours_enqueue(struct mbuf **mp, int *offp, int nxt)
{
        /* save values for later, use after dequeue */
        if (*offp != sizeof(struct ip)) {
                struct m_tag *mtag;
                struct ipoffnxt *ion;

                /* mbuf tags are expensive, but only used for header options */
                mtag = m_tag_get(PACKET_TAG_IP_OFFNXT, sizeof(*ion),
                    M_NOWAIT);
                if (mtag == NULL) {
                        ipstat_inc(ips_idropped);
                        m_freemp(mp);
                        return IPPROTO_DONE;
                }
                ion = (struct ipoffnxt *)(mtag + 1);
                ion->ion_off = *offp;
                ion->ion_nxt = nxt;

                m_tag_prepend(*mp, mtag);
        }

        niq_enqueue(&ipintrq, *mp);
        *mp = NULL;
        return IPPROTO_DONE;
}

/*
 * Dequeue and process locally delivered packets.
 * This is called with exclusive NET_LOCK().
 */
void
ipintr(void)
{
        struct mbuf *m;

        while ((m = niq_dequeue(&ipintrq)) != NULL) {
                struct m_tag *mtag;
                int off, nxt;

#ifdef DIAGNOSTIC
                if ((m->m_flags & M_PKTHDR) == 0)
                        panic("ipintr no HDR");
#endif
                mtag = m_tag_find(m, PACKET_TAG_IP_OFFNXT, NULL);
                if (mtag != NULL) {
                        struct ipoffnxt *ion;

                        ion = (struct ipoffnxt *)(mtag + 1);
                        off = ion->ion_off;
                        nxt = ion->ion_nxt;

                        m_tag_delete(m, mtag);
                } else {
                        struct ip *ip;

                        ip = mtod(m, struct ip *);
                        off = ip->ip_hl << 2;
                        nxt = ip->ip_p;
                }

                nxt = ip_deliver(&m, &off, nxt, AF_INET, 0, NULL);
                KASSERT(nxt == IPPROTO_DONE);
        }
}

/*
 * IPv4 input routine.
 *
 * Checksum and byte swap header.  Process options. Forward or deliver.
 */
void
ipv4_input(struct ifnet *ifp, struct mbuf *m, struct netstack *ns)
{
        int off, nxt;

        off = 0;
        nxt = ip_input_if(&m, &off, IPPROTO_IPV4, AF_UNSPEC, ifp, ns);
        KASSERT(nxt == IPPROTO_DONE);
}

struct mbuf *
ipv4_check(struct ifnet *ifp, struct mbuf *m)
{
        struct ip *ip;
        int hlen, len;

        if (m->m_len < sizeof(*ip)) {
                m = m_pullup(m, sizeof(*ip));
                if (m == NULL) {
                        ipstat_inc(ips_toosmall);
                        return (NULL);
                }
        }

        ip = mtod(m, struct ip *);
        if (ip->ip_v != IPVERSION) {
                ipstat_inc(ips_badvers);
                goto bad;
        }

        hlen = ip->ip_hl << 2;
        if (hlen < sizeof(*ip)) {       /* minimum header length */
                ipstat_inc(ips_badhlen);
                goto bad;
        }
        if (hlen > m->m_len) {
                m = m_pullup(m, hlen);
                if (m == NULL) {
                        ipstat_inc(ips_badhlen);
                        return (NULL);
                }
                ip = mtod(m, struct ip *);
        }

        /* 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) {
                        ipstat_inc(ips_badaddr);
                        goto bad;
                }
        }

        if (!ISSET(m->m_pkthdr.csum_flags, M_IPV4_CSUM_IN_OK)) {
                if (ISSET(m->m_pkthdr.csum_flags, M_IPV4_CSUM_IN_BAD)) {
                        ipstat_inc(ips_badsum);
                        goto bad;
                }

                ipstat_inc(ips_inswcsum);
                if (in_cksum(m, hlen) != 0) {
                        ipstat_inc(ips_badsum);
                        goto bad;
                }

                SET(m->m_pkthdr.csum_flags, M_IPV4_CSUM_IN_OK);
        }

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

        /*
         * Convert fields to host representation.
         */
        if (len < hlen) {
                ipstat_inc(ips_badlen);
                goto bad;
        }

        /*
         * 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) {
                ipstat_inc(ips_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);
        }

        return (m);
bad:
        m_freem(m);
        return (NULL);
}

int
ip_input_if(struct mbuf **mp, int *offp, int nxt, int af, struct ifnet *ifp,
    struct netstack *ns)
{
        struct route iproute, *ro = NULL;
        struct mbuf *m;
        struct ip *ip;
        int hlen;
#if NPF > 0
        struct in_addr odst;
#endif
        int flags = 0;

        KASSERT(*offp == 0);

        ipstat_inc(ips_total);
        m = *mp = ipv4_check(ifp, *mp);
        if (m == NULL)
                goto bad;

        ip = mtod(m, struct ip *);

#if NCARP > 0
        if (carp_lsdrop(ifp, m, AF_INET, &ip->ip_src.s_addr,
            &ip->ip_dst.s_addr, (ip->ip_p == IPPROTO_ICMP ? 0 : 1)))
                goto bad;
#endif

#if NPF > 0
        /*
         * Packet filter
         */
        odst = ip->ip_dst;
        if (pf_test(AF_INET, PF_IN, ifp, mp) != PF_PASS)
                goto bad;
        m = *mp;
        if (m == NULL)
                goto bad;

        ip = mtod(m, struct ip *);
        if (odst.s_addr != ip->ip_dst.s_addr)
                SET(flags, IP_REDIRECT);
#endif

        switch (atomic_load_int(&ip_forwarding)) {
        case 2:
                SET(flags, IP_FORWARDING_IPSEC);
                /* FALLTHROUGH */
        case 1:
                SET(flags, IP_FORWARDING);
                break;
        }
        if (atomic_load_int(&ip_directedbcast))
                SET(flags, IP_ALLOWBROADCAST);

        hlen = ip->ip_hl << 2;

        /*
         * 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, ifp, flags)) {
                m = *mp = NULL;
                goto bad;
        }

        if (ns == NULL) {
                ro = &iproute;
                ro->ro_rt = NULL;
        } else {
                ro = &ns->ns_route;
        }
        switch (in_ouraddr(m, ifp, ro, flags)) {
        case 2:
                goto bad;
        case 1:
                nxt = ip_ours(mp, offp, nxt, af, ns);
                goto out;
        }

        if (IN_MULTICAST(ip->ip_dst.s_addr)) {
                /*
                 * Make sure M_MCAST is set.  It should theoretically
                 * already be there, but let's play safe because upper
                 * layers check for this flag.
                 */
                m->m_flags |= M_MCAST;

#ifdef MROUTING
                if (atomic_load_int(&ipmforwarding) &&
                    ip_mrouter[ifp->if_rdomain]) {
                        int error;

                        if (m->m_flags & M_EXT) {
                                if ((m = *mp = m_pullup(m, hlen)) == NULL) {
                                        ipstat_inc(ips_toosmall);
                                        goto bad;
                                }
                                ip = mtod(m, struct ip *);
                        }
                        /*
                         * 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().)
                         */
                        KERNEL_LOCK();
                        error = ip_mforward(m, ifp, flags);
                        KERNEL_UNLOCK();
                        if (error) {
                                ipstat_inc(ips_cantforward);
                                goto bad;
                        }

                        /*
                         * The process-level routing daemon needs to receive
                         * all multicast IGMP packets, whether or not this
                         * host belongs to their destination groups.
                         */
                        if (ip->ip_p == IPPROTO_IGMP) {
                                nxt = ip_ours(mp, offp, nxt, af, ns);
                                goto out;
                        }
                        ipstat_inc(ips_forward);
                }
#endif
                /*
                 * See if we belong to the destination multicast group on the
                 * arrival interface.
                 */
                if (!in_hasmulti(&ip->ip_dst, ifp)) {
                        ipstat_inc(ips_notmember);
                        if (!IN_LOCAL_GROUP(ip->ip_dst.s_addr))
                                ipstat_inc(ips_cantforward);
                        goto bad;
                }
                nxt = ip_ours(mp, offp, nxt, af, ns);
                goto out;
        }

#if NCARP > 0
        if (ip->ip_p == IPPROTO_ICMP &&
            carp_lsdrop(ifp, m, AF_INET, &ip->ip_src.s_addr,
            &ip->ip_dst.s_addr, 1))
                goto bad;
#endif
        /*
         * Not for us; forward if possible and desirable.
         */
        if (!ISSET(flags, IP_FORWARDING)) {
                ipstat_inc(ips_cantforward);
                goto bad;
        }
#ifdef IPSEC
        if (ipsec_in_use) {
                int rv;

                rv = ipsec_forward_check(m, hlen, AF_INET);
                if (rv != 0) {
                        ipstat_inc(ips_cantforward);
                        goto bad;
                }
                /*
                 * Fall through, forward packet. Outbound IPsec policy
                 * checking will occur in ip_output().
                 */
        }
#endif /* IPSEC */

        ip_forward(m, ifp, ro, flags);
        *mp = NULL;
        if (ro == &iproute)
                rtfree(ro->ro_rt);
        return IPPROTO_DONE;
 bad:
        nxt = IPPROTO_DONE;
        m_freemp(mp);
 out:
        if (ro == &iproute)
                rtfree(ro->ro_rt);
        return nxt;
}

int
ip_fragcheck(struct mbuf **mp, int *offp)
{
        struct ip *ip;
        struct ipq *fp;
        struct ipqent *ipqe;
        int hlen;
        uint16_t mff;

        ip = mtod(*mp, struct ip *);
        hlen = ip->ip_hl << 2;

        /*
         * If offset or more fragments 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 (ISSET(ip->ip_off, htons(IP_OFFMASK | IP_MF))) {
                if ((*mp)->m_flags & M_EXT) {           /* XXX */
                        if ((*mp = m_pullup(*mp, hlen)) == NULL) {
                                ipstat_inc(ips_toosmall);
                                return IPPROTO_DONE;
                        }
                        ip = mtod(*mp, struct ip *);
                }

                /*
                 * 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 = ISSET(ip->ip_off, htons(IP_MF));
                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) {
                                ipstat_inc(ips_badfrags);
                                m_freemp(mp);
                                return IPPROTO_DONE;
                        }
                }
                ip->ip_off = htons(ntohs(ip->ip_off) << 3);

                mtx_enter(&ipq_mutex);

                /*
                 * Look for queue of fragments
                 * of this datagram.
                 */
                LIST_FOREACH(fp, &ipq, ipq_q) {
                        if (ip->ip_id == fp->ipq_id &&
                            ip->ip_src.s_addr == fp->ipq_src.s_addr &&
                            ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
                            ip->ip_p == fp->ipq_p)
                                break;
                }

                /*
                 * 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) {
                        int ip_maxqueue_local = atomic_load_int(&ip_maxqueue);

                        ipstat_inc(ips_fragments);
                        if (ip_frags + 1 > ip_maxqueue_local) {
                                ip_flush(ip_maxqueue_local);
                                ipstat_inc(ips_rcvmemdrop);
                                goto bad;
                        }

                        ipqe = pool_get(&ipqent_pool, PR_NOWAIT);
                        if (ipqe == NULL) {
                                ipstat_inc(ips_rcvmemdrop);
                                goto bad;
                        }
                        ip_frags++;
                        ipqe->ipqe_mff = mff;
                        ipqe->ipqe_m = *mp;
                        ipqe->ipqe_ip = ip;
                        *mp = ip_reass(ipqe, fp);
                        if (*mp == NULL)
                                goto bad;
                        ipstat_inc(ips_reassembled);
                        ip = mtod(*mp, struct ip *);
                        hlen = ip->ip_hl << 2;
                        ip->ip_len = htons(ntohs(ip->ip_len) + hlen);
                } else {
                        if (fp != NULL)
                                ip_freef(fp);
                }

                mtx_leave(&ipq_mutex);
        }

        *offp = hlen;
        return ip->ip_p;

 bad:
        mtx_leave(&ipq_mutex);
        m_freemp(mp);
        return IPPROTO_DONE;
}

#ifndef INET6
#define IPSTAT_INC(name)        ipstat_inc(ips_##name)
#else
#define IPSTAT_INC(name)        (af == AF_INET ?        \
    ipstat_inc(ips_##name) : ip6stat_inc(ip6s_##name))
#endif

int
ip_deliver(struct mbuf **mp, int *offp, int nxt, int af, int shared,
    struct netstack *ns)
{
#ifdef INET6
        int nest = 0;
#endif

        /*
         * Tell launch routine the next header
         */
        IPSTAT_INC(delivered);

        while (nxt != IPPROTO_DONE) {
                const struct protosw *psw;
                int naf;

                switch (af) {
                case AF_INET:
                        psw = &inetsw[ip_protox[nxt]];
                        break;
#ifdef INET6
                case AF_INET6:
                        psw = &inet6sw[ip6_protox[nxt]];
                        break;
#endif
                }
                if (shared && !ISSET(psw->pr_flags, PR_MPINPUT)) {
                        /* delivery not finished, decrement counter, queue */
                        switch (af) {
                        case AF_INET:
                                counters_dec(ipcounters, ips_delivered);
                                return ip_ours_enqueue(mp, offp, nxt);
#ifdef INET6
                        case AF_INET6:
                                counters_dec(ip6counters, ip6s_delivered);
                                return ip6_ours_enqueue(mp, offp, nxt);
#endif
                        }
                        break;
                }

#ifdef INET6
                if (af == AF_INET6 &&
                    (++nest > atomic_load_int(&ip6_hdrnestlimit))) {
                        ip6stat_inc(ip6s_toomanyhdr);
                        goto bad;
                }
#endif

                /*
                 * protection against faulty packet - there should be
                 * more sanity checks in header chain processing.
                 */
                if ((*mp)->m_pkthdr.len < *offp) {
                        IPSTAT_INC(tooshort);
                        goto bad;
                }

#ifdef IPSEC
                if (ipsec_in_use) {
                        if (ipsec_local_check(*mp, *offp, nxt, af) != 0) {
                                IPSTAT_INC(cantforward);
                                goto bad;
                        }
                }
                /* Otherwise, just fall through and deliver the packet */
#endif

                switch (nxt) {
                case IPPROTO_IPV4:
                        naf = AF_INET;
                        ipstat_inc(ips_delivered);
                        break;
#ifdef INET6
                case IPPROTO_IPV6:
                        naf = AF_INET6;
                        ip6stat_inc(ip6s_delivered);
                        break;
#endif
                default:
                        naf = af;
                        break;
                }
                nxt = (*psw->pr_input)(mp, offp, nxt, af, ns);
                af = naf;
        }
        return nxt;
 bad:
        m_freemp(mp);
        return IPPROTO_DONE;
}
#undef IPSTAT_INC

int
in_ouraddr(struct mbuf *m, struct ifnet *ifp, struct route *ro, int flags)
{
        struct rtentry          *rt;
        struct ip               *ip;
        int                      match = 0;

#if NPF > 0
        switch (pf_ouraddr(m)) {
        case 0:
                return (0);
        case 1:
                return (1);
        default:
                /* pf does not know it */
                break;
        }
#endif

        ip = mtod(m, struct ip *);

        if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
            ip->ip_dst.s_addr == INADDR_ANY) {
                m->m_flags |= M_BCAST;
                return (1);
        }

        rt = route_mpath(ro, &ip->ip_dst, &ip->ip_src, m->m_pkthdr.ph_rtableid);
        if (rt != NULL) {
                if (ISSET(rt->rt_flags, RTF_LOCAL))
                        match = 1;

                /*
                 * If directedbcast is enabled we only consider it local
                 * if it is received on the interface with that address.
                 */
                if (ISSET(rt->rt_flags, RTF_BROADCAST) &&
                    (!ISSET(flags, IP_ALLOWBROADCAST) ||
                    rt->rt_ifidx == ifp->if_index)) {
                        match = 1;

                        /* Make sure M_BCAST is set */
                        m->m_flags |= M_BCAST;
                }
        }

        if (!match) {
                struct ifaddr *ifa;

                /*
                 * No local address or broadcast address found, so check for
                 * ancient classful broadcast addresses.
                 * It must have been broadcast on the link layer, and for an
                 * address on the interface it was received on.
                 */
                if (!ISSET(m->m_flags, M_BCAST) ||
                    !IN_CLASSFULBROADCAST(ip->ip_dst.s_addr, ip->ip_dst.s_addr))
                        return (0);

                if (ifp->if_rdomain != rtable_l2(m->m_pkthdr.ph_rtableid))
                        return (0);
                /*
                 * The check in the loop assumes you only rx a packet on an UP
                 * interface, and that M_BCAST will only be set on a BROADCAST
                 * interface.
                 */
                NET_ASSERT_LOCKED();
                TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) {
                        if (ifa->ifa_addr->sa_family != AF_INET)
                                continue;

                        if (IN_CLASSFULBROADCAST(ip->ip_dst.s_addr,
                            ifatoia(ifa)->ia_addr.sin_addr.s_addr)) {
                                match = 1;
                                break;
                        }
                }
        } else if (!ISSET(flags, IP_FORWARDING) &&
            rt->rt_ifidx != ifp->if_index &&
            !((ifp->if_flags & IFF_LOOPBACK) || (ifp->if_type == IFT_ENC) ||
            (m->m_pkthdr.pf.flags & PF_TAG_TRANSLATE_LOCALHOST))) {
                /* received on wrong interface. */
#if NCARP > 0
                struct ifnet *out_if;

                /*
                 * Virtual IPs on carp interfaces need to be checked also
                 * against the parent interface and other carp interfaces
                 * sharing the same parent.
                 */
                out_if = if_get(rt->rt_ifidx);
                if (!(out_if && carp_strict_addr_chk(out_if, ifp))) {
                        ipstat_inc(ips_wrongif);
                        match = 2;
                }
                if_put(out_if);
#else
                ipstat_inc(ips_wrongif);
                match = 2;
#endif
        }

        return (match);
}

/*
 * 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 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;
        u_int8_t ecn, ecn0;

        MUTEX_ASSERT_LOCKED(&ipq_mutex);

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

        /*
         * If first fragment to arrive, create a reassembly queue.
         */
        if (fp == NULL) {
                fp = pool_get(&ipq_pool, PR_NOWAIT);
                if (fp == NULL)
                        goto dropfrag;
                LIST_INSERT_HEAD(&ipq, fp, ipq_q);
                fp->ipq_ttl = IPFRAGTTL;
                fp->ipq_p = ipqe->ipqe_ip->ip_p;
                fp->ipq_id = ipqe->ipqe_ip->ip_id;
                LIST_INIT(&fp->ipq_fragq);
                fp->ipq_src = ipqe->ipqe_ip->ip_src;
                fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
                p = NULL;
                goto insert;
        }

        /*
         * Handle ECN by comparing this segment with the first one;
         * if CE is set, do not lose CE.
         * drop if CE and not-ECT are mixed for the same packet.
         */
        ecn = ipqe->ipqe_ip->ip_tos & IPTOS_ECN_MASK;
        ecn0 = LIST_FIRST(&fp->ipq_fragq)->ipqe_ip->ip_tos & IPTOS_ECN_MASK;
        if (ecn == IPTOS_ECN_CE) {
                if (ecn0 == IPTOS_ECN_NOTECT)
                        goto dropfrag;
                if (ecn0 != IPTOS_ECN_CE)
                        LIST_FIRST(&fp->ipq_fragq)->ipqe_ip->ip_tos |=
                            IPTOS_ECN_CE;
        }
        if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
                goto dropfrag;

        /*
         * Find a segment which begins after this one does.
         */
        for (p = NULL, q = LIST_FIRST(&fp->ipq_fragq); q != NULL;
            p = q, q = LIST_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 = LIST_NEXT(q, ipqe_q);
                m_freem(q->ipqe_m);
                LIST_REMOVE(q, ipqe_q);
                pool_put(&ipqent_pool, q);
                ip_frags--;
        }

insert:
        /*
         * Stick new segment in its place;
         * check for complete reassembly.
         */
        if (p == NULL) {
                LIST_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
        } else {
                LIST_INSERT_AFTER(p, ipqe, ipqe_q);
        }
        next = 0;
        for (p = NULL, q = LIST_FIRST(&fp->ipq_fragq); q != NULL;
            p = q, q = LIST_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 = LIST_FIRST(&fp->ipq_fragq);
        ip = q->ipqe_ip;
        if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
                ipstat_inc(ips_toolong);
                ip_freef(fp);
                return (0);
        }
        m = q->ipqe_m;
        t = m->m_next;
        m->m_next = 0;
        m_cat(m, t);
        nq = LIST_NEXT(q, ipqe_q);
        pool_put(&ipqent_pool, q);
        ip_frags--;
        for (q = nq; q != NULL; q = nq) {
                t = q->ipqe_m;
                nq = LIST_NEXT(q, ipqe_q);
                pool_put(&ipqent_pool, q);
                ip_frags--;
                m_removehdr(t);
                m_cat(m, t);
        }

        /*
         * 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);
        pool_put(&ipq_pool, fp);
        m->m_len += (ip->ip_hl << 2);
        m->m_data -= (ip->ip_hl << 2);
        m_calchdrlen(m);
        return (m);

dropfrag:
        ipstat_inc(ips_fragdropped);
        m_freem(m);
        pool_put(&ipqent_pool, ipqe);
        ip_frags--;
        return (NULL);
}

/*
 * Free a fragment reassembly header and all
 * associated datagrams.
 */
void
ip_freef(struct ipq *fp)
{
        struct ipqent *q;

        MUTEX_ASSERT_LOCKED(&ipq_mutex);

        while ((q = LIST_FIRST(&fp->ipq_fragq)) != NULL) {
                LIST_REMOVE(q, ipqe_q);
                m_freem(q->ipqe_m);
                pool_put(&ipqent_pool, q);
                ip_frags--;
        }
        LIST_REMOVE(fp, ipq_q);
        pool_put(&ipq_pool, fp);
}

/*
 * IP timer processing;
 * if a timer expires on a reassembly queue, discard it.
 */
void
ip_slowtimo(void)
{
        struct ipq *fp, *nfp;

        mtx_enter(&ipq_mutex);
        LIST_FOREACH_SAFE(fp, &ipq, ipq_q, nfp) {
                if (--fp->ipq_ttl == 0) {
                        ipstat_inc(ips_fragtimeout);
                        ip_freef(fp);
                }
        }
        mtx_leave(&ipq_mutex);
}

/*
 * Flush a bunch of datagram fragments, till we are down to 75%.
 */
void
ip_flush(int maxqueue)
{
        int max = 50;

        MUTEX_ASSERT_LOCKED(&ipq_mutex);

        while (!LIST_EMPTY(&ipq) && ip_frags > maxqueue * 3 / 4 && --max) {
                ipstat_inc(ips_fragdropped);
                ip_freef(LIST_FIRST(&ipq));
        }
}

/*
 * 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 ifnet *ifp, int flags)
{
        struct ip *ip = mtod(m, struct ip *);
        unsigned int rtableid = m->m_pkthdr.ph_rtableid;
        struct rtentry *rt;
        struct sockaddr_in ipaddr;
        u_char *cp;
        struct ip_timestamp ipt;
        struct in_ifaddr *ia;
        int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
        struct in_addr sin, dst;
        u_int32_t ntime;

        dst = ip->ip_dst;
        cp = (u_char *)(ip + 1);
        cnt = (ip->ip_hl << 2) - sizeof (struct ip);

        KERNEL_LOCK();
        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 (atomic_load_int(&ip_dosourceroute) == 0) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_SRCFAIL;
                                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;
                        }
                        memset(&ipaddr, 0, sizeof(ipaddr));
                        ipaddr.sin_family = AF_INET;
                        ipaddr.sin_len = sizeof(ipaddr);
                        ipaddr.sin_addr = ip->ip_dst;
                        ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr),
                            m->m_pkthdr.ph_rtableid));
                        if (ia == NULL) {
                                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(m, cp, ip->ip_src);
                                break;
                        }

                        /*
                         * locate outgoing interface
                         */
                        memset(&ipaddr, 0, sizeof(ipaddr));
                        ipaddr.sin_family = AF_INET;
                        ipaddr.sin_len = sizeof(ipaddr);
                        memcpy(&ipaddr.sin_addr, cp + off,
                            sizeof(ipaddr.sin_addr));
                        /* keep packet in the virtual instance */
                        rt = rtalloc(sintosa(&ipaddr), RT_RESOLVE, rtableid);
                        if (!rtisvalid(rt) || ((opt == IPOPT_SSRR) &&
                            ISSET(rt->rt_flags, RTF_GATEWAY))) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_SRCFAIL;
                                rtfree(rt);
                                goto bad;
                        }
                        ia = ifatoia(rt->rt_ifa);
                        memcpy(cp + off, &ia->ia_addr.sin_addr,
                            sizeof(struct in_addr));
                        rtfree(rt);
                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                        ip->ip_dst = ipaddr.sin_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;
                        memset(&ipaddr, 0, sizeof(ipaddr));
                        ipaddr.sin_family = AF_INET;
                        ipaddr.sin_len = sizeof(ipaddr);
                        ipaddr.sin_addr = ip->ip_dst;
                        /*
                         * locate outgoing interface; if we're the destination,
                         * use the incoming interface (should be same).
                         * Again keep the packet inside the virtual instance.
                         */
                        rt = rtalloc(sintosa(&ipaddr), RT_RESOLVE, rtableid);
                        if (!rtisvalid(rt)) {
                                type = ICMP_UNREACH;
                                code = ICMP_UNREACH_HOST;
                                rtfree(rt);
                                goto bad;
                        }
                        ia = ifatoia(rt->rt_ifa);
                        memcpy(cp + off, &ia->ia_addr.sin_addr,
                            sizeof(struct in_addr));
                        rtfree(rt);
                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                        break;

                case IPOPT_TS:
                        code = cp - (u_char *)ip;
                        if (optlen < sizeof(struct ip_timestamp))
                                goto bad;
                        memcpy(&ipt, cp, sizeof(struct ip_timestamp));
                        if (ipt.ipt_ptr < 5 || ipt.ipt_len < 5)
                                goto bad;
                        if (ipt.ipt_ptr - 1 + sizeof(u_int32_t) > ipt.ipt_len) {
                                if (++ipt.ipt_oflw == 0)
                                        goto bad;
                                break;
                        }
                        memcpy(&sin, cp + ipt.ipt_ptr - 1, sizeof sin);
                        switch (ipt.ipt_flg) {

                        case IPOPT_TS_TSONLY:
                                break;

                        case IPOPT_TS_TSANDADDR:
                                if (ipt.ipt_ptr - 1 + sizeof(u_int32_t) +
                                    sizeof(struct in_addr) > ipt.ipt_len)
                                        goto bad;
                                memset(&ipaddr, 0, sizeof(ipaddr));
                                ipaddr.sin_family = AF_INET;
                                ipaddr.sin_len = sizeof(ipaddr);
                                ipaddr.sin_addr = dst;
                                ia = ifatoia(ifaof_ifpforaddr(sintosa(&ipaddr),
                                    ifp));
                                if (ia == NULL)
                                        continue;
                                memcpy(&sin, &ia->ia_addr.sin_addr,
                                    sizeof(struct in_addr));
                                ipt.ipt_ptr += sizeof(struct in_addr);
                                break;

                        case IPOPT_TS_PRESPEC:
                                if (ipt.ipt_ptr - 1 + sizeof(u_int32_t) +
                                    sizeof(struct in_addr) > ipt.ipt_len)
                                        goto bad;
                                memset(&ipaddr, 0, sizeof(ipaddr));
                                ipaddr.sin_family = AF_INET;
                                ipaddr.sin_len = sizeof(ipaddr);
                                ipaddr.sin_addr = sin;
                                if (ifa_ifwithaddr(sintosa(&ipaddr),
                                    m->m_pkthdr.ph_rtableid) == 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();
                        memcpy(cp + ipt.ipt_ptr - 1, &ntime, sizeof(u_int32_t));
                        ipt.ipt_ptr += sizeof(u_int32_t);
                }
        }
        KERNEL_UNLOCK();
        if (forward && ISSET(flags, IP_FORWARDING)) {
                ip_forward(m, ifp, NULL, flags | IP_REDIRECT);
                return (1);
        }
        return (0);
bad:
        KERNEL_UNLOCK();
        icmp_error(m, type, code, 0, 0);
        ipstat_inc(ips_badoptions);
        return (1);
}

/*
 * Save incoming source route for use in replies,
 * to be picked up later by ip_srcroute if the receiver is interested.
 */
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) {
                ipstat_inc(ips_idropped);
                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;

        if (atomic_load_int(&ip_dosourceroute) == 0)
                return (NULL);

        mtag = m_tag_find(m0, PACKET_TAG_SRCROUTE, NULL);
        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) {
                ipstat_inc(ips_idropped);
                return (NULL);
        }

#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;
        memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), &isr->isr_nop,
            OPTSIZ);
        q = (struct in_addr *)(mtod(m, caddr_t) +
            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, (struct m_tag *)isr);
        return (m);
}

/*
 * Strip out IP options, at higher level protocol in the kernel.
 */
void
ip_stripoptions(struct mbuf *m)
{
        int i;
        struct ip *ip = mtod(m, struct ip *);
        caddr_t opts;
        int olen;

        olen = (ip->ip_hl<<2) - sizeof (struct ip);
        opts = (caddr_t)(ip + 1);
        i = m->m_len - (sizeof (struct ip) + olen);
        memmove(opts, opts  + olen, i);
        m->m_len -= olen;
        if (m->m_flags & M_PKTHDR)
                m->m_pkthdr.len -= olen;
        ip->ip_hl = sizeof(struct ip) >> 2;
        ip->ip_len = htons(ntohs(ip->ip_len) - olen);
}

const u_char inetctlerrmap[PRC_NCMDS] = {
        0,              0,              0,              0,
        0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
        EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
        EMSGSIZE,       EHOSTUNREACH,   0,              0,
        0,              0,              0,              0,
        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 ip_forwarding 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, struct ifnet *ifp, struct route *ro, int flags)
{
        struct ip *ip = mtod(m, struct ip *);
        struct route iproute;
        struct rtentry *rt;
        u_int rtableid = m->m_pkthdr.ph_rtableid;
        u_int8_t loopcnt = m->m_pkthdr.ph_loopcnt;
        u_int icmp_len;
        char icmp_buf[68];
        CTASSERT(sizeof(icmp_buf) <= MHLEN);
        u_short mflags, pfflags;
        struct mbuf *mcopy;
        int error = 0, type = 0, code = 0, destmtu = 0;
        u_int32_t dest;

        dest = 0;
        if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
                ipstat_inc(ips_cantforward);
                m_freem(m);
                goto done;
        }
        if (ip->ip_ttl <= IPTTLDEC) {
                icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
                goto done;
        }

        if (ro == NULL) {
                ro = &iproute;
                ro->ro_rt = NULL;
        }
        rt = route_mpath(ro, &ip->ip_dst, &ip->ip_src, rtableid);
        if (rt == NULL) {
                ipstat_inc(ips_noroute);
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
                goto done;
        }

        /*
         * Save at most 68 bytes of the packet in case we need to generate
         * an ICMP message to the src.  The data is saved on the stack.
         * A new mbuf is only allocated when ICMP is actually created.
         */
        icmp_len = min(sizeof(icmp_buf), ntohs(ip->ip_len));
        mflags = m->m_flags;
        pfflags = m->m_pkthdr.pf.flags;
        m_copydata(m, 0, icmp_len, icmp_buf);

        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.
         * Don't send redirect if we advertise destination's arp address
         * as ours (proxy arp).
         */
        if (rt->rt_ifidx == ifp->if_index &&
            !ISSET(rt->rt_flags, RTF_DYNAMIC|RTF_MODIFIED) &&
            satosin(rt_key(rt))->sin_addr.s_addr != INADDR_ANY &&
            !ISSET(flags, IP_REDIRECT) &&
#if NETHER > 0
            !arpproxy(satosin(rt_key(rt))->sin_addr, rtableid) &&
#endif
            atomic_load_int(&ip_sendredirects)) {
                if ((ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_netmask) ==
                    ifatoia(rt->rt_ifa)->ia_net) {
                    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;
                }
        }

        error = ip_output(m, NULL, ro, flags | IP_FORWARDING, NULL, NULL, 0);
        rt = ro->ro_rt;
        if (error)
                ipstat_inc(ips_cantforward);
        else {
                ipstat_inc(ips_forward);
                if (type)
                        ipstat_inc(ips_redirectsent);
                else
                        goto done;
        }
        switch (error) {
        case 0:                         /* forwarded, but need redirect */
                /* type, code set above */
                break;

        case EMSGSIZE:
                type = ICMP_UNREACH;
                code = ICMP_UNREACH_NEEDFRAG;
                if (rt != NULL) {
                        u_int rtmtu;

                        rtmtu = atomic_load_int(&rt->rt_mtu);
                        if (rtmtu != 0) {
                                destmtu = rtmtu;
                        } else {
                                struct ifnet *destifp;

                                destifp = if_get(rt->rt_ifidx);
                                if (destifp != NULL)
                                        destmtu = destifp->if_mtu;
                                if_put(destifp);
                        }
                }
                ipstat_inc(ips_cantfrag);
                if (destmtu == 0)
                        goto done;
                break;

        case EACCES:
                /*
                 * pf(4) blocked the packet. There is no need to send an ICMP
                 * packet back since pf(4) takes care of it.
                 */
                goto done;

        case ENOBUFS:
                /*
                 * 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 the underlying interface is rate-limited.
                 */
                goto done;

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

        mcopy = m_gethdr(M_DONTWAIT, MT_DATA);
        if (mcopy == NULL)
                goto done;
        mcopy->m_len = mcopy->m_pkthdr.len = icmp_len;
        mcopy->m_flags |= (mflags & M_COPYFLAGS);
        mcopy->m_pkthdr.ph_rtableid = rtableid;
        mcopy->m_pkthdr.ph_ifidx = ifp->if_index;
        mcopy->m_pkthdr.ph_loopcnt = loopcnt;
        mcopy->m_pkthdr.pf.flags |= (pfflags & PF_TAG_GENERATED);
        memcpy(mcopy->m_data, icmp_buf, icmp_len);
        icmp_error(mcopy, type, code, dest, destmtu);

 done:
        if (ro == &iproute)
                rtfree(ro->ro_rt);
}

#ifndef SMALL_KERNEL

int
ip_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
    size_t newlen)
{
        int oldval, newval, error;

        /* Almost all sysctl names at this level are terminal. */
        if (namelen != 1 && name[0] != IPCTL_IFQUEUE &&
            name[0] != IPCTL_ARPQUEUE)
                return (ENOTDIR);

        switch (name[0]) {
        case IPCTL_SOURCEROUTE:
                return (sysctl_securelevel_int(oldp, oldlenp, newp, newlen,
                    &ip_dosourceroute));
        case IPCTL_MTUDISC:
                oldval = newval = atomic_load_int(&ip_mtudisc);
                error = sysctl_int_bounded(oldp, oldlenp, newp, newlen,
                    &newval, 0, 1);
                if (error == 0 && oldval != newval &&
                    oldval == atomic_cas_uint(&ip_mtudisc, oldval, newval) &&
                    newval == 0) {
                        NET_LOCK();
                        rt_timer_queue_flush(&ip_mtudisc_timeout_q);
                        NET_UNLOCK();
                }

                return (error);
        case IPCTL_MTUDISCTIMEOUT:
                oldval = newval = atomic_load_int(&ip_mtudisc_timeout);
                error = sysctl_int_bounded(oldp, oldlenp, newp, newlen,
                    &newval, 0, INT_MAX);
                if (error == 0 && oldval != newval) {
                        rw_enter_write(&sysctl_lock);
                        atomic_store_int(&ip_mtudisc_timeout, newval);
                        rt_timer_queue_change(&ip_mtudisc_timeout_q, newval);
                        rw_exit_write(&sysctl_lock);
                }

                return (error);
#ifdef IPSEC
        case IPCTL_ENCDEBUG:
        case IPCTL_IPSEC_STATS:
        case IPCTL_IPSEC_EXPIRE_ACQUIRE:
        case IPCTL_IPSEC_EMBRYONIC_SA_TIMEOUT:
        case IPCTL_IPSEC_REQUIRE_PFS:
        case IPCTL_IPSEC_SOFT_ALLOCATIONS:
        case IPCTL_IPSEC_ALLOCATIONS:
        case IPCTL_IPSEC_SOFT_BYTES:
        case IPCTL_IPSEC_BYTES:
        case IPCTL_IPSEC_TIMEOUT:
        case IPCTL_IPSEC_SOFT_TIMEOUT:
        case IPCTL_IPSEC_SOFT_FIRSTUSE:
        case IPCTL_IPSEC_FIRSTUSE:
        case IPCTL_IPSEC_ENC_ALGORITHM:
        case IPCTL_IPSEC_AUTH_ALGORITHM:
        case IPCTL_IPSEC_IPCOMP_ALGORITHM:
                return (ipsec_sysctl(name, namelen, oldp, oldlenp, newp,
                    newlen));
#endif
        case IPCTL_IFQUEUE:
                return (sysctl_niq(name + 1, namelen - 1,
                    oldp, oldlenp, newp, newlen, &ipintrq));
        case IPCTL_ARPQUEUE:
                return (sysctl_niq(name + 1, namelen - 1,
                    oldp, oldlenp, newp, newlen, &arpinq));
        case IPCTL_ARPQUEUED:
                return (sysctl_rdint(oldp, oldlenp, newp,
                    atomic_load_int(&la_hold_total)));
        case IPCTL_STATS:
                return (ip_sysctl_ipstat(oldp, oldlenp, newp));
#ifdef MROUTING
        case IPCTL_MRTSTATS:
                return (mrt_sysctl_mrtstat(oldp, oldlenp, newp));
        case IPCTL_MRTMFC:
                if (newp)
                        return (EPERM);
                return (mrt_sysctl_mfc(oldp, oldlenp));
        case IPCTL_MRTVIF:
                if (newp)
                        return (EPERM);
                return (mrt_sysctl_vif(oldp, oldlenp));
#else
        case IPCTL_MRTPROTO:
        case IPCTL_MRTSTATS:
        case IPCTL_MRTMFC:
        case IPCTL_MRTVIF:
                return (EOPNOTSUPP);
#endif
        case IPCTL_MULTIPATH:
                oldval = newval = atomic_load_int(&ipmultipath);
                error = sysctl_int_bounded(oldp, oldlenp, newp, newlen,
                    &newval, 0, 1);
                if (error == 0 && oldval != newval) {
                        atomic_store_int(&ipmultipath, newval);
                        membar_producer();
                        atomic_inc_long(&rtgeneration);
                }

                return (error);
        default:
                return (sysctl_bounded_arr(ipctl_vars, nitems(ipctl_vars),
                    name, namelen, oldp, oldlenp, newp, newlen));
        }
        /* NOTREACHED */
}

int
ip_sysctl_ipstat(void *oldp, size_t *oldlenp, void *newp)
{
        uint64_t counters[ips_ncounters];
        struct ipstat ipstat;
        u_long *words = (u_long *)&ipstat;
        int i;

        CTASSERT(sizeof(ipstat) == (nitems(counters) * sizeof(u_long)));
        memset(&ipstat, 0, sizeof ipstat);
        counters_read(ipcounters, counters, nitems(counters), NULL);

        for (i = 0; i < nitems(counters); i++)
                words[i] = (u_long)counters[i];

        return (sysctl_rdstruct(oldp, oldlenp, newp, &ipstat, sizeof(ipstat)));
}
#endif /* SMALL_KERNEL */

void
ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
    struct mbuf *m)
{
        if (inp->inp_socket->so_options & SO_TIMESTAMP) {
                struct timeval tv;

                m_microtime(m, &tv);
                *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
                    SCM_TIMESTAMP, SOL_SOCKET);
                if (*mp)
                        mp = &(*mp)->m_next;
        }

        if (inp->inp_flags & INP_RECVDSTADDR) {
                *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
                    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
#ifdef notyet
        /* this code is broken and will probably never be fixed. */
        /* options were tossed already */
        if (inp->inp_flags & INP_RECVOPTS) {
                *mp = sbcreatecontrol((caddr_t) 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((caddr_t) ip_srcroute(m),
                    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;
                struct ifnet *ifp;

                ifp = if_get(m->m_pkthdr.ph_ifidx);
                if (ifp == NULL || ifp->if_sadl == NULL) {
                        memset(&sdl, 0, sizeof(sdl));
                        sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
                        sdl.sdl_family = AF_LINK;
                        sdl.sdl_index = ifp != NULL ? ifp->if_index : 0;
                        sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
                        *mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
                            IP_RECVIF, IPPROTO_IP);
                } else {
                        *mp = sbcreatecontrol((caddr_t) ifp->if_sadl,
                            ifp->if_sadl->sdl_len, IP_RECVIF, IPPROTO_IP);
                }
                if (*mp)
                        mp = &(*mp)->m_next;
                if_put(ifp);
        }
        if (inp->inp_flags & INP_RECVTTL) {
                *mp = sbcreatecontrol((caddr_t) &ip->ip_ttl,
                    sizeof(u_int8_t), IP_RECVTTL, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
        if (inp->inp_flags & INP_RECVRTABLE) {
                u_int rtableid = inp->inp_rtableid;

#if NPF > 0
                if (m && m->m_pkthdr.pf.flags & PF_TAG_DIVERTED) {
                        struct pf_divert *divert;

                        divert = pf_find_divert(m);
                        KASSERT(divert != NULL);
                        rtableid = divert->rdomain;
                }
#endif

                *mp = sbcreatecontrol((caddr_t) &rtableid,
                    sizeof(u_int), IP_RECVRTABLE, IPPROTO_IP);
                if (*mp)
                        mp = &(*mp)->m_next;
        }
}

void
ip_send_do_dispatch(void *xmq, int flags)
{
        struct mbuf_queue *mq = xmq;
        struct mbuf *m;
        struct mbuf_list ml;
        struct m_tag *mtag;

        mq_delist(mq, &ml);
        if (ml_empty(&ml))
                return;

        NET_LOCK_SHARED();
        while ((m = ml_dequeue(&ml)) != NULL) {
                u_int32_t ipsecflowinfo = 0;

                if ((mtag = m_tag_find(m, PACKET_TAG_IPSEC_FLOWINFO, NULL))
                    != NULL) {
                        ipsecflowinfo = *(u_int32_t *)(mtag + 1);
                        m_tag_delete(m, mtag);
                }
                ip_output(m, NULL, NULL, flags, NULL, NULL, ipsecflowinfo);
        }
        NET_UNLOCK_SHARED();
}

void
ip_sendraw_dispatch(void *xmq)
{
        ip_send_do_dispatch(xmq, IP_RAWOUTPUT);
}

void
ip_send_dispatch(void *xmq)
{
        ip_send_do_dispatch(xmq, 0);
}

void
ip_send(struct mbuf *m)
{
        mq_enqueue(&ipsend_mq, m);
        task_add(net_tq(0), &ipsend_task);
}

void
ip_send_raw(struct mbuf *m)
{
        mq_enqueue(&ipsendraw_mq, m);
        task_add(net_tq(0), &ipsendraw_task);
}