No empty .Rs/.Re

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

/*      $NetBSD: ip_output.c,v 1.204 2009/07/16 04:09:51 minskim Exp $  */

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

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

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 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_output.c 8.3 (Berkeley) 1/21/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ip_output.c,v 1.204 2009/07/16 04:09:51 minskim Exp $");

#include "opt_pfil_hooks.h"
#include "opt_inet.h"
#include "opt_ipsec.h"
#include "opt_mrouting.h"

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/kauth.h>
#ifdef FAST_IPSEC
#include <sys/domain.h>
#endif
#include <sys/systm.h>
#include <sys/proc.h>

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

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_private.h>
#include <netinet/in_offload.h>

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

#include <machine/stdarg.h>

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

#ifdef FAST_IPSEC
#include <netipsec/ipsec.h>
#include <netipsec/key.h>
#include <netipsec/xform.h>
#endif  /* FAST_IPSEC*/

#ifdef IPSEC_NAT_T
#include <netinet/udp.h>
#endif

static struct mbuf *ip_insertoptions(struct mbuf *, struct mbuf *, int *);
static struct ifnet *ip_multicast_if(struct in_addr *, int *);
static void ip_mloopback(struct ifnet *, struct mbuf *,
    const struct sockaddr_in *);

#ifdef PFIL_HOOKS
extern struct pfil_head inet_pfil_hook;                 /* XXX */
#endif

int     ip_do_loopback_cksum = 0;

/*
 * IP output.  The packet in mbuf chain m contains a skeletal IP
 * header (with len, off, ttl, proto, tos, src, dst).
 * The mbuf chain containing the packet will be freed.
 * The mbuf opt, if present, will not be freed.
 */
int
ip_output(struct mbuf *m0, ...)
{
        struct rtentry *rt;
        struct ip *ip;
        struct ifnet *ifp;
        struct mbuf *m = m0;
        int hlen = sizeof (struct ip);
        int len, error = 0;
        struct route iproute;
        const struct sockaddr_in *dst;
        struct in_ifaddr *ia;
        struct ifaddr *xifa;
        struct mbuf *opt;
        struct route *ro;
        int flags, sw_csum;
        int *mtu_p;
        u_long mtu;
        struct ip_moptions *imo;
        struct socket *so;
        va_list ap;
#ifdef IPSEC_NAT_T
        int natt_frag = 0;
#endif
#ifdef IPSEC
        struct secpolicy *sp = NULL;
#endif /*IPSEC*/
#ifdef FAST_IPSEC
        struct inpcb *inp;
        struct secpolicy *sp = NULL;
        int s;
#endif
        u_int16_t ip_len;
        union {
                struct sockaddr         dst;
                struct sockaddr_in      dst4;
        } u;
        struct sockaddr *rdst = &u.dst; /* real IP destination, as opposed
                                         * to the nexthop
                                         */

        len = 0;
        va_start(ap, m0);
        opt = va_arg(ap, struct mbuf *);
        ro = va_arg(ap, struct route *);
        flags = va_arg(ap, int);
        imo = va_arg(ap, struct ip_moptions *);
        so = va_arg(ap, struct socket *);
        if (flags & IP_RETURNMTU)
                mtu_p = va_arg(ap, int *);
        else
                mtu_p = NULL;
        va_end(ap);

        MCLAIM(m, &ip_tx_mowner);
#ifdef FAST_IPSEC
        if (so != NULL && so->so_proto->pr_domain->dom_family == AF_INET)
                inp = (struct inpcb *)so->so_pcb;
        else
                inp = NULL;
#endif /* FAST_IPSEC */

#ifdef  DIAGNOSTIC
        if ((m->m_flags & M_PKTHDR) == 0)
                panic("ip_output: no HDR");

        if ((m->m_pkthdr.csum_flags & (M_CSUM_TCPv6|M_CSUM_UDPv6)) != 0) {
                panic("ip_output: IPv6 checksum offload flags: %d",
                    m->m_pkthdr.csum_flags);
        }

        if ((m->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4)) ==
            (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                panic("ip_output: conflicting checksum offload flags: %d",
                    m->m_pkthdr.csum_flags);
        }
#endif
        if (opt) {
                m = ip_insertoptions(m, opt, &len);
                if (len >= sizeof(struct ip))
                        hlen = len;
        }
        ip = mtod(m, struct ip *);
        /*
         * Fill in IP header.
         */
        if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
                ip->ip_v = IPVERSION;
                ip->ip_off = htons(0);
                /* ip->ip_id filled in after we find out source ia */
                ip->ip_hl = hlen >> 2;
                IP_STATINC(IP_STAT_LOCALOUT);
        } else {
                hlen = ip->ip_hl << 2;
        }
        /*
         * Route packet.
         */
        memset(&iproute, 0, sizeof(iproute));
        if (ro == NULL)
                ro = &iproute;
        sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
        dst = satocsin(rtcache_getdst(ro));
        /*
         * If there is a cached route,
         * check that it is to the same destination
         * and is still up.  If not, free it and try again.
         * The address family should also be checked in case of sharing the
         * cache with IPv6.
         */
        if (dst == NULL)
                ;
        else if (dst->sin_family != AF_INET ||
                 !in_hosteq(dst->sin_addr, ip->ip_dst))
                rtcache_free(ro);

        if ((rt = rtcache_validate(ro)) == NULL &&
            (rt = rtcache_update(ro, 1)) == NULL) {
                dst = &u.dst4;
                rtcache_setdst(ro, &u.dst);
        }
        /*
         * If routing to interface only,
         * short circuit routing lookup.
         */
        if (flags & IP_ROUTETOIF) {
                if ((ia = ifatoia(ifa_ifwithladdr(sintocsa(dst)))) == NULL) {
                        IP_STATINC(IP_STAT_NOROUTE);
                        error = ENETUNREACH;
                        goto bad;
                }
                ifp = ia->ia_ifp;
                mtu = ifp->if_mtu;
                ip->ip_ttl = 1;
        } else if ((IN_MULTICAST(ip->ip_dst.s_addr) ||
            ip->ip_dst.s_addr == INADDR_BROADCAST) &&
            imo != NULL && imo->imo_multicast_ifp != NULL) {
                ifp = imo->imo_multicast_ifp;
                mtu = ifp->if_mtu;
                IFP_TO_IA(ifp, ia);
        } else {
                if (rt == NULL)
                        rt = rtcache_init(ro);
                if (rt == NULL) {
                        IP_STATINC(IP_STAT_NOROUTE);
                        error = EHOSTUNREACH;
                        goto bad;
                }
                ia = ifatoia(rt->rt_ifa);
                ifp = rt->rt_ifp;
                if ((mtu = rt->rt_rmx.rmx_mtu) == 0)
                        mtu = ifp->if_mtu;
                rt->rt_use++;
                if (rt->rt_flags & RTF_GATEWAY)
                        dst = satosin(rt->rt_gateway);
        }
        if (IN_MULTICAST(ip->ip_dst.s_addr) ||
            (ip->ip_dst.s_addr == INADDR_BROADCAST)) {
                struct in_multi *inm;

                m->m_flags |= (ip->ip_dst.s_addr == INADDR_BROADCAST) ?
                        M_BCAST : M_MCAST;
                /*
                 * See if the caller provided any multicast options
                 */
                if (imo != NULL)
                        ip->ip_ttl = imo->imo_multicast_ttl;
                else
                        ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;

                /*
                 * if we don't know the outgoing ifp yet, we can't generate
                 * output
                 */
                if (!ifp) {
                        IP_STATINC(IP_STAT_NOROUTE);
                        error = ENETUNREACH;
                        goto bad;
                }

                /*
                 * If the packet is multicast or broadcast, confirm that
                 * the outgoing interface can transmit it.
                 */
                if (((m->m_flags & M_MCAST) &&
                     (ifp->if_flags & IFF_MULTICAST) == 0) ||
                    ((m->m_flags & M_BCAST) &&
                     (ifp->if_flags & (IFF_BROADCAST|IFF_POINTOPOINT)) == 0))  {
                        IP_STATINC(IP_STAT_NOROUTE);
                        error = ENETUNREACH;
                        goto bad;
                }
                /*
                 * If source address not specified yet, use an address
                 * of outgoing interface.
                 */
                if (in_nullhost(ip->ip_src)) {
                        struct in_ifaddr *xia;

                        IFP_TO_IA(ifp, xia);
                        if (!xia) {
                                error = EADDRNOTAVAIL;
                                goto bad;
                        }
                        xifa = &xia->ia_ifa;
                        if (xifa->ifa_getifa != NULL) {
                                xia = ifatoia((*xifa->ifa_getifa)(xifa, rdst));
                        }
                        ip->ip_src = xia->ia_addr.sin_addr;
                }

                IN_LOOKUP_MULTI(ip->ip_dst, ifp, inm);
                if (inm != NULL &&
                   (imo == NULL || imo->imo_multicast_loop)) {
                        /*
                         * If we belong to the destination multicast group
                         * on the outgoing interface, and the caller did not
                         * forbid loopback, loop back a copy.
                         */
                        ip_mloopback(ifp, m, &u.dst4);
                }
#ifdef MROUTING
                else {
                        /*
                         * If we are acting as a multicast router, perform
                         * multicast forwarding as if the packet had just
                         * arrived on the interface to which we are about
                         * to send.  The multicast forwarding function
                         * recursively calls this function, using the
                         * IP_FORWARDING flag to prevent infinite recursion.
                         *
                         * Multicasts that are looped back by ip_mloopback(),
                         * above, will be forwarded by the ip_input() routine,
                         * if necessary.
                         */
                        extern struct socket *ip_mrouter;

                        if (ip_mrouter && (flags & IP_FORWARDING) == 0) {
                                if (ip_mforward(m, ifp) != 0) {
                                        m_freem(m);
                                        goto done;
                                }
                        }
                }
#endif
                /*
                 * Multicasts with a time-to-live of zero may be looped-
                 * back, above, but must not be transmitted on a network.
                 * Also, multicasts addressed to the loopback interface
                 * are not sent -- the above call to ip_mloopback() will
                 * loop back a copy if this host actually belongs to the
                 * destination group on the loopback interface.
                 */
                if (ip->ip_ttl == 0 || (ifp->if_flags & IFF_LOOPBACK) != 0) {
                        m_freem(m);
                        goto done;
                }

                goto sendit;
        }
        /*
         * If source address not specified yet, use address
         * of outgoing interface.
         */
        if (in_nullhost(ip->ip_src)) {
                xifa = &ia->ia_ifa;
                if (xifa->ifa_getifa != NULL)
                        ia = ifatoia((*xifa->ifa_getifa)(xifa, rdst));
                ip->ip_src = ia->ia_addr.sin_addr;
        }

        /*
         * packets with Class-D address as source are not valid per
         * RFC 1112
         */
        if (IN_MULTICAST(ip->ip_src.s_addr)) {
                IP_STATINC(IP_STAT_ODROPPED);
                error = EADDRNOTAVAIL;
                goto bad;
        }

        /*
         * Look for broadcast address and
         * and verify user is allowed to send
         * such a packet.
         */
        if (in_broadcast(dst->sin_addr, ifp)) {
                if ((ifp->if_flags & IFF_BROADCAST) == 0) {
                        error = EADDRNOTAVAIL;
                        goto bad;
                }
                if ((flags & IP_ALLOWBROADCAST) == 0) {
                        error = EACCES;
                        goto bad;
                }
                /* don't allow broadcast messages to be fragmented */
                if (ntohs(ip->ip_len) > ifp->if_mtu) {
                        error = EMSGSIZE;
                        goto bad;
                }
                m->m_flags |= M_BCAST;
        } else
                m->m_flags &= ~M_BCAST;

sendit:
        if ((flags & (IP_FORWARDING|IP_NOIPNEWID)) == 0) {
                if (m->m_pkthdr.len < IP_MINFRAGSIZE) {
                        ip->ip_id = 0;
                } else if ((m->m_pkthdr.csum_flags & M_CSUM_TSOv4) == 0) {
                        ip->ip_id = ip_newid(ia);
                } else {

                        /*
                         * TSO capable interfaces (typically?) increment
                         * ip_id for each segment.
                         * "allocate" enough ids here to increase the chance
                         * for them to be unique.
                         *
                         * note that the following calculation is not
                         * needed to be precise.  wasting some ip_id is fine.
                         */

                        unsigned int segsz = m->m_pkthdr.segsz;
                        unsigned int datasz = ntohs(ip->ip_len) - hlen;
                        unsigned int num = howmany(datasz, segsz);

                        ip->ip_id = ip_newid_range(ia, num);
                }
        }
        /*
         * If we're doing Path MTU Discovery, we need to set DF unless
         * the route's MTU is locked.
         */
        if ((flags & IP_MTUDISC) != 0 && rt != NULL &&
            (rt->rt_rmx.rmx_locks & RTV_MTU) == 0)
                ip->ip_off |= htons(IP_DF);

        /* Remember the current ip_len */
        ip_len = ntohs(ip->ip_len);

#ifdef IPSEC
        /* get SP for this packet */
        if (so == NULL)
                sp = ipsec4_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND,
                    flags, &error);
        else {
                if (IPSEC_PCB_SKIP_IPSEC(sotoinpcb_hdr(so)->inph_sp,
                                         IPSEC_DIR_OUTBOUND))
                        goto skip_ipsec;
                sp = ipsec4_getpolicybysock(m, IPSEC_DIR_OUTBOUND, so, &error);
        }

        if (sp == NULL) {
                IPSEC_STATINC(IPSEC_STAT_IN_INVAL);
                goto bad;
        }

        error = 0;

        /* check policy */
        switch (sp->policy) {
        case IPSEC_POLICY_DISCARD:
                /*
                 * This packet is just discarded.
                 */
                IPSEC_STATINC(IPSEC_STAT_OUT_POLVIO);
                goto bad;

        case IPSEC_POLICY_BYPASS:
        case IPSEC_POLICY_NONE:
                /* no need to do IPsec. */
                goto skip_ipsec;

        case IPSEC_POLICY_IPSEC:
                if (sp->req == NULL) {
                        /* XXX should be panic ? */
                        printf("ip_output: No IPsec request specified.\n");
                        error = EINVAL;
                        goto bad;
                }
                break;

        case IPSEC_POLICY_ENTRUST:
        default:
                printf("ip_output: Invalid policy found. %d\n", sp->policy);
        }

#ifdef IPSEC_NAT_T
        /*
         * NAT-T ESP fragmentation: don't do IPSec processing now,
         * we'll do it on each fragmented packet.
         */
        if (sp->req->sav &&
            ((sp->req->sav->natt_type & UDP_ENCAP_ESPINUDP) ||
             (sp->req->sav->natt_type & UDP_ENCAP_ESPINUDP_NON_IKE))) {
                if (ntohs(ip->ip_len) > sp->req->sav->esp_frag) {
                        natt_frag = 1;
                        mtu = sp->req->sav->esp_frag;
                        goto skip_ipsec;
                }
        }
#endif /* IPSEC_NAT_T */

        /*
         * ipsec4_output() expects ip_len and ip_off in network
         * order.  They have been set to network order above.
         */

    {
        struct ipsec_output_state state;
        memset(&state, 0, sizeof(state));
        state.m = m;
        if (flags & IP_ROUTETOIF) {
                state.ro = &iproute;
                memset(&iproute, 0, sizeof(iproute));
        } else
                state.ro = ro;
        state.dst = sintocsa(dst);

        /*
         * We can't defer the checksum of payload data if
         * we're about to encrypt/authenticate it.
         *
         * XXX When we support crypto offloading functions of
         * XXX network interfaces, we need to reconsider this,
         * XXX since it's likely that they'll support checksumming,
         * XXX as well.
         */
        if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                in_delayed_cksum(m);
                m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv4|M_CSUM_UDPv4);
        }

        error = ipsec4_output(&state, sp, flags);

        m = state.m;
        if (flags & IP_ROUTETOIF) {
                /*
                 * if we have tunnel mode SA, we may need to ignore
                 * IP_ROUTETOIF.
                 */
                if (state.ro != &iproute ||
                    rtcache_validate(state.ro) != NULL) {
                        flags &= ~IP_ROUTETOIF;
                        ro = state.ro;
                }
        } else
                ro = state.ro;
        dst = satocsin(state.dst);
        if (error) {
                /* mbuf is already reclaimed in ipsec4_output. */
                m0 = NULL;
                switch (error) {
                case EHOSTUNREACH:
                case ENETUNREACH:
                case EMSGSIZE:
                case ENOBUFS:
                case ENOMEM:
                        break;
                default:
                        printf("ip4_output (ipsec): error code %d\n", error);
                        /*fall through*/
                case ENOENT:
                        /* don't show these error codes to the user */
                        error = 0;
                        break;
                }
                goto bad;
        }

        /* be sure to update variables that are affected by ipsec4_output() */
        ip = mtod(m, struct ip *);
        hlen = ip->ip_hl << 2;
        ip_len = ntohs(ip->ip_len);

        if ((rt = rtcache_validate(ro)) == NULL) {
                if ((flags & IP_ROUTETOIF) == 0) {
                        printf("ip_output: "
                                "can't update route after IPsec processing\n");
                        error = EHOSTUNREACH;   /*XXX*/
                        goto bad;
                }
        } else {
                /* nobody uses ia beyond here */
                if (state.encap) {
                        ifp = rt->rt_ifp;
                        if ((mtu = rt->rt_rmx.rmx_mtu) == 0)
                                mtu = ifp->if_mtu;
                }
        }
    }
skip_ipsec:
#endif /*IPSEC*/
#ifdef FAST_IPSEC
        /*
         * Check the security policy (SP) for the packet and, if
         * required, do IPsec-related processing.  There are two
         * cases here; the first time a packet is sent through
         * it will be untagged and handled by ipsec4_checkpolicy.
         * If the packet is resubmitted to ip_output (e.g. after
         * AH, ESP, etc. processing), there will be a tag to bypass
         * the lookup and related policy checking.
         */
        if (!ipsec_outdone(m)) {
                s = splsoftnet();
                if (inp != NULL &&
                    IPSEC_PCB_SKIP_IPSEC(inp->inp_sp, IPSEC_DIR_OUTBOUND)) {
                        splx(s);
                        goto spd_done;
                }
                sp = ipsec4_checkpolicy(m, IPSEC_DIR_OUTBOUND, flags,
                                &error, inp);
                /*
                 * There are four return cases:
                 *    sp != NULL                    apply IPsec policy
                 *    sp == NULL, error == 0        no IPsec handling needed
                 *    sp == NULL, error == -EINVAL  discard packet w/o error
                 *    sp == NULL, error != 0        discard packet, report error
                 */
                if (sp != NULL) {
#ifdef IPSEC_NAT_T
                        /*
                         * NAT-T ESP fragmentation: don't do IPSec processing now,
                         * we'll do it on each fragmented packet.
                         */
                        if (sp->req->sav &&
                                        ((sp->req->sav->natt_type & UDP_ENCAP_ESPINUDP) ||
                                         (sp->req->sav->natt_type & UDP_ENCAP_ESPINUDP_NON_IKE))) {
                                if (ntohs(ip->ip_len) > sp->req->sav->esp_frag) {
                                        natt_frag = 1;
                                        mtu = sp->req->sav->esp_frag;
                                        splx(s);
                                        goto spd_done;
                                }
                        }
#endif /* IPSEC_NAT_T */

                        /*
                         * Do delayed checksums now because we send before
                         * this is done in the normal processing path.
                         */
                        if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                                in_delayed_cksum(m);
                                m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv4|M_CSUM_UDPv4);
                        }

#ifdef __FreeBSD__
                        ip->ip_len = htons(ip->ip_len);
                        ip->ip_off = htons(ip->ip_off);
#endif

                        /* NB: callee frees mbuf */
                        error = ipsec4_process_packet(m, sp->req, flags, 0);
                        /*
                         * Preserve KAME behaviour: ENOENT can be returned
                         * when an SA acquire is in progress.  Don't propagate
                         * this to user-level; it confuses applications.
                         *
                         * XXX this will go away when the SADB is redone.
                         */
                        if (error == ENOENT)
                                error = 0;
                        splx(s);
                        goto done;
                } else {
                        splx(s);

                        if (error != 0) {
                                /*
                                 * Hack: -EINVAL is used to signal that a packet
                                 * should be silently discarded.  This is typically
                                 * because we asked key management for an SA and
                                 * it was delayed (e.g. kicked up to IKE).
                                 */
                                if (error == -EINVAL)
                                        error = 0;
                                goto bad;
                        } else {
                                /* No IPsec processing for this packet. */
                        }
                }
        }
spd_done:
#endif /* FAST_IPSEC */

#ifdef PFIL_HOOKS
        /*
         * Run through list of hooks for output packets.
         */
        if ((error = pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT)) != 0)
                goto done;
        if (m == NULL)
                goto done;

        ip = mtod(m, struct ip *);
        hlen = ip->ip_hl << 2;
        ip_len = ntohs(ip->ip_len);
#endif /* PFIL_HOOKS */

        m->m_pkthdr.csum_data |= hlen << 16;

#if IFA_STATS
        /*
         * search for the source address structure to
         * maintain output statistics.
         */
        INADDR_TO_IA(ip->ip_src, ia);
#endif

        /* Maybe skip checksums on loopback interfaces. */
        if (IN_NEED_CHECKSUM(ifp, M_CSUM_IPv4)) {
                m->m_pkthdr.csum_flags |= M_CSUM_IPv4;
        }
        sw_csum = m->m_pkthdr.csum_flags & ~ifp->if_csum_flags_tx;
        /*
         * If small enough for mtu of path, or if using TCP segmentation
         * offload, can just send directly.
         */
        if (ip_len <= mtu ||
            (m->m_pkthdr.csum_flags & M_CSUM_TSOv4) != 0) {
#if IFA_STATS
                if (ia)
                        ia->ia_ifa.ifa_data.ifad_outbytes += ip_len;
#endif
                /*
                 * Always initialize the sum to 0!  Some HW assisted
                 * checksumming requires this.
                 */
                ip->ip_sum = 0;

                if ((m->m_pkthdr.csum_flags & M_CSUM_TSOv4) == 0) {
                        /*
                         * Perform any checksums that the hardware can't do
                         * for us.
                         *
                         * XXX Does any hardware require the {th,uh}_sum
                         * XXX fields to be 0?
                         */
                        if (sw_csum & M_CSUM_IPv4) {
                                KASSERT(IN_NEED_CHECKSUM(ifp, M_CSUM_IPv4));
                                ip->ip_sum = in_cksum(m, hlen);
                                m->m_pkthdr.csum_flags &= ~M_CSUM_IPv4;
                        }
                        if (sw_csum & (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                                if (IN_NEED_CHECKSUM(ifp,
                                    sw_csum & (M_CSUM_TCPv4|M_CSUM_UDPv4))) {
                                        in_delayed_cksum(m);
                                }
                                m->m_pkthdr.csum_flags &=
                                    ~(M_CSUM_TCPv4|M_CSUM_UDPv4);
                        }
                }

#ifdef IPSEC
                /* clean ipsec history once it goes out of the node */
                ipsec_delaux(m);
#endif

                if (__predict_true(
                    (m->m_pkthdr.csum_flags & M_CSUM_TSOv4) == 0 ||
                    (ifp->if_capenable & IFCAP_TSOv4) != 0)) {
                        error =
                            (*ifp->if_output)(ifp, m,
                                (m->m_flags & M_MCAST) ?
                                    sintocsa(rdst) : sintocsa(dst),
                                rt);
                } else {
                        error =
                            ip_tso_output(ifp, m,
                                (m->m_flags & M_MCAST) ?
                                    sintocsa(rdst) : sintocsa(dst),
                                rt);
                }
                goto done;
        }

        /*
         * We can't use HW checksumming if we're about to
         * to fragment the packet.
         *
         * XXX Some hardware can do this.
         */
        if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                if (IN_NEED_CHECKSUM(ifp,
                    m->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4))) {
                        in_delayed_cksum(m);
                }
                m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv4|M_CSUM_UDPv4);
        }

        /*
         * Too large for interface; fragment if possible.
         * Must be able to put at least 8 bytes per fragment.
         */
        if (ntohs(ip->ip_off) & IP_DF) {
                if (flags & IP_RETURNMTU)
                        *mtu_p = mtu;
                error = EMSGSIZE;
                IP_STATINC(IP_STAT_CANTFRAG);
                goto bad;
        }

        error = ip_fragment(m, ifp, mtu);
        if (error) {
                m = NULL;
                goto bad;
        }

        for (; m; m = m0) {
                m0 = m->m_nextpkt;
                m->m_nextpkt = 0;
                if (error == 0) {
#if IFA_STATS
                        if (ia)
                                ia->ia_ifa.ifa_data.ifad_outbytes +=
                                    ntohs(ip->ip_len);
#endif
#ifdef IPSEC
                        /* clean ipsec history once it goes out of the node */
                        ipsec_delaux(m);
#endif /* IPSEC */

#ifdef IPSEC_NAT_T
                        /*
                         * If we get there, the packet has not been handeld by
                         * IPSec whereas it should have. Now that it has been
                         * fragmented, re-inject it in ip_output so that IPsec
                         * processing can occur.
                         */
                        if (natt_frag) {
                                error = ip_output(m, opt,
                                    ro, flags, imo, so, mtu_p);
                        } else
#endif /* IPSEC_NAT_T */
                        {
                                KASSERT((m->m_pkthdr.csum_flags &
                                    (M_CSUM_UDPv4 | M_CSUM_TCPv4)) == 0);
                                error = (*ifp->if_output)(ifp, m,
                                    (m->m_flags & M_MCAST) ?
                                        sintocsa(rdst) : sintocsa(dst),
                                    rt);
                        }
                } else
                        m_freem(m);
        }

        if (error == 0)
                IP_STATINC(IP_STAT_FRAGMENTED);
done:
        rtcache_free(&iproute);

#ifdef IPSEC
        if (sp != NULL) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                        printf("DP ip_output call free SP:%p\n", sp));
                key_freesp(sp);
        }
#endif /* IPSEC */
#ifdef FAST_IPSEC
        if (sp != NULL)
                KEY_FREESP(&sp);
#endif /* FAST_IPSEC */

        return (error);
bad:
        m_freem(m);
        goto done;
}

int
ip_fragment(struct mbuf *m, struct ifnet *ifp, u_long mtu)
{
        struct ip *ip, *mhip;
        struct mbuf *m0;
        int len, hlen, off;
        int mhlen, firstlen;
        struct mbuf **mnext;
        int sw_csum = m->m_pkthdr.csum_flags;
        int fragments = 0;
        int s;
        int error = 0;

        ip = mtod(m, struct ip *);
        hlen = ip->ip_hl << 2;
        if (ifp != NULL)
                sw_csum &= ~ifp->if_csum_flags_tx;

        len = (mtu - hlen) &~ 7;
        if (len < 8) {
                m_freem(m);
                return (EMSGSIZE);
        }

        firstlen = len;
        mnext = &m->m_nextpkt;

        /*
         * Loop through length of segment after first fragment,
         * make new header and copy data of each part and link onto chain.
         */
        m0 = m;
        mhlen = sizeof (struct ip);
        for (off = hlen + len; off < ntohs(ip->ip_len); off += len) {
                MGETHDR(m, M_DONTWAIT, MT_HEADER);
                if (m == 0) {
                        error = ENOBUFS;
                        IP_STATINC(IP_STAT_ODROPPED);
                        goto sendorfree;
                }
                MCLAIM(m, m0->m_owner);
                *mnext = m;
                mnext = &m->m_nextpkt;
                m->m_data += max_linkhdr;
                mhip = mtod(m, struct ip *);
                *mhip = *ip;
                /* we must inherit MCAST and BCAST flags */
                m->m_flags |= m0->m_flags & (M_MCAST|M_BCAST);
                if (hlen > sizeof (struct ip)) {
                        mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
                        mhip->ip_hl = mhlen >> 2;
                }
                m->m_len = mhlen;
                mhip->ip_off = ((off - hlen) >> 3) +
                    (ntohs(ip->ip_off) & ~IP_MF);
                if (ip->ip_off & htons(IP_MF))
                        mhip->ip_off |= IP_MF;
                if (off + len >= ntohs(ip->ip_len))
                        len = ntohs(ip->ip_len) - off;
                else
                        mhip->ip_off |= IP_MF;
                HTONS(mhip->ip_off);
                mhip->ip_len = htons((u_int16_t)(len + mhlen));
                m->m_next = m_copym(m0, off, len, M_DONTWAIT);
                if (m->m_next == 0) {
                        error = ENOBUFS;        /* ??? */
                        IP_STATINC(IP_STAT_ODROPPED);
                        goto sendorfree;
                }
                m->m_pkthdr.len = mhlen + len;
                m->m_pkthdr.rcvif = (struct ifnet *)0;
                mhip->ip_sum = 0;
                if (sw_csum & M_CSUM_IPv4) {
                        mhip->ip_sum = in_cksum(m, mhlen);
                        KASSERT((m->m_pkthdr.csum_flags & M_CSUM_IPv4) == 0);
                } else {
                        m->m_pkthdr.csum_flags |= M_CSUM_IPv4;
                        m->m_pkthdr.csum_data |= mhlen << 16;
                }
                IP_STATINC(IP_STAT_OFRAGMENTS);
                fragments++;
        }
        /*
         * Update first fragment by trimming what's been copied out
         * and updating header, then send each fragment (in order).
         */
        m = m0;
        m_adj(m, hlen + firstlen - ntohs(ip->ip_len));
        m->m_pkthdr.len = hlen + firstlen;
        ip->ip_len = htons((u_int16_t)m->m_pkthdr.len);
        ip->ip_off |= htons(IP_MF);
        ip->ip_sum = 0;
        if (sw_csum & M_CSUM_IPv4) {
                ip->ip_sum = in_cksum(m, hlen);
                m->m_pkthdr.csum_flags &= ~M_CSUM_IPv4;
        } else {
                KASSERT(m->m_pkthdr.csum_flags & M_CSUM_IPv4);
                KASSERT(M_CSUM_DATA_IPv4_IPHL(m->m_pkthdr.csum_data) >=
                        sizeof(struct ip));
        }
sendorfree:
        /*
         * If there is no room for all the fragments, don't queue
         * any of them.
         */
        if (ifp != NULL) {
                s = splnet();
                if (ifp->if_snd.ifq_maxlen - ifp->if_snd.ifq_len < fragments &&
                    error == 0) {
                        error = ENOBUFS;
                        IP_STATINC(IP_STAT_ODROPPED);
                        IFQ_INC_DROPS(&ifp->if_snd);
                }
                splx(s);
        }
        if (error) {
                for (m = m0; m; m = m0) {
                        m0 = m->m_nextpkt;
                        m->m_nextpkt = NULL;
                        m_freem(m);
                }
        }
        return (error);
}

/*
 * Process a delayed payload checksum calculation.
 */
void
in_delayed_cksum(struct mbuf *m)
{
        struct ip *ip;
        u_int16_t csum, offset;

        ip = mtod(m, struct ip *);
        offset = ip->ip_hl << 2;
        csum = in4_cksum(m, 0, offset, ntohs(ip->ip_len) - offset);
        if (csum == 0 && (m->m_pkthdr.csum_flags & M_CSUM_UDPv4) != 0)
                csum = 0xffff;

        offset += M_CSUM_DATA_IPv4_OFFSET(m->m_pkthdr.csum_data);

        if ((offset + sizeof(u_int16_t)) > m->m_len) {
                /* This happen when ip options were inserted
                printf("in_delayed_cksum: pullup len %d off %d proto %d\n",
                    m->m_len, offset, ip->ip_p);
                 */
                m_copyback(m, offset, sizeof(csum), (void *) &csum);
        } else
                *(u_int16_t *)(mtod(m, char *) + offset) = csum;
}

/*
 * Determine the maximum length of the options to be inserted;
 * we would far rather allocate too much space rather than too little.
 */

u_int
ip_optlen(struct inpcb *inp)
{
        struct mbuf *m = inp->inp_options;

        if (m && m->m_len > offsetof(struct ipoption, ipopt_dst))
                return (m->m_len - offsetof(struct ipoption, ipopt_dst));
        else
                return 0;
}


/*
 * Insert IP options into preformed packet.
 * Adjust IP destination as required for IP source routing,
 * as indicated by a non-zero in_addr at the start of the options.
 */
static struct mbuf *
ip_insertoptions(struct mbuf *m, struct mbuf *opt, int *phlen)
{
        struct ipoption *p = mtod(opt, struct ipoption *);
        struct mbuf *n;
        struct ip *ip = mtod(m, struct ip *);
        unsigned optlen;

        optlen = opt->m_len - sizeof(p->ipopt_dst);
        if (optlen + ntohs(ip->ip_len) > IP_MAXPACKET)
                return (m);             /* XXX should fail */
        if (!in_nullhost(p->ipopt_dst))
                ip->ip_dst = p->ipopt_dst;
        if (M_READONLY(m) || M_LEADINGSPACE(m) < optlen) {
                MGETHDR(n, M_DONTWAIT, MT_HEADER);
                if (n == 0)
                        return (m);
                MCLAIM(n, m->m_owner);
                M_MOVE_PKTHDR(n, m);
                m->m_len -= sizeof(struct ip);
                m->m_data += sizeof(struct ip);
                n->m_next = m;
                m = n;
                m->m_len = optlen + sizeof(struct ip);
                m->m_data += max_linkhdr;
                bcopy((void *)ip, mtod(m, void *), sizeof(struct ip));
        } else {
                m->m_data -= optlen;
                m->m_len += optlen;
                memmove(mtod(m, void *), ip, sizeof(struct ip));
        }
        m->m_pkthdr.len += optlen;
        ip = mtod(m, struct ip *);
        bcopy((void *)p->ipopt_list, (void *)(ip + 1), (unsigned)optlen);
        *phlen = sizeof(struct ip) + optlen;
        ip->ip_len = htons(ntohs(ip->ip_len) + optlen);
        return (m);
}

/*
 * Copy options from ip to jp,
 * omitting those not copied during fragmentation.
 */
int
ip_optcopy(struct ip *ip, struct ip *jp)
{
        u_char *cp, *dp;
        int opt, optlen, cnt;

        cp = (u_char *)(ip + 1);
        dp = (u_char *)(jp + 1);
        cnt = (ip->ip_hl << 2) - sizeof (struct ip);
        for (; cnt > 0; cnt -= optlen, cp += optlen) {
                opt = cp[0];
                if (opt == IPOPT_EOL)
                        break;
                if (opt == IPOPT_NOP) {
                        /* Preserve for IP mcast tunnel's LSRR alignment. */
                        *dp++ = IPOPT_NOP;
                        optlen = 1;
                        continue;
                }
#ifdef DIAGNOSTIC
                if (cnt < IPOPT_OLEN + sizeof(*cp))
                        panic("malformed IPv4 option passed to ip_optcopy");
#endif
                optlen = cp[IPOPT_OLEN];
#ifdef DIAGNOSTIC
                if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt)
                        panic("malformed IPv4 option passed to ip_optcopy");
#endif
                /* bogus lengths should have been caught by ip_dooptions */
                if (optlen > cnt)
                        optlen = cnt;
                if (IPOPT_COPIED(opt)) {
                        bcopy((void *)cp, (void *)dp, (unsigned)optlen);
                        dp += optlen;
                }
        }
        for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
                *dp++ = IPOPT_EOL;
        return (optlen);
}

/*
 * IP socket option processing.
 */
int
ip_ctloutput(int op, struct socket *so, struct sockopt *sopt)
{
        struct inpcb *inp = sotoinpcb(so);
        int optval = 0;
        int error = 0;
#if defined(IPSEC) || defined(FAST_IPSEC)
        struct lwp *l = curlwp; /*XXX*/
#endif

        if (sopt->sopt_level != IPPROTO_IP) {
                if (sopt->sopt_level == SOL_SOCKET && sopt->sopt_name == SO_NOHEADER)
                        return 0;
                return ENOPROTOOPT;
        }

        switch (op) {
        case PRCO_SETOPT:
                switch (sopt->sopt_name) {
                case IP_OPTIONS:
#ifdef notyet
                case IP_RETOPTS:
#endif
                        error = ip_pcbopts(&inp->inp_options, sopt);
                        break;

                case IP_TOS:
                case IP_TTL:
                case IP_MINTTL:
                case IP_RECVOPTS:
                case IP_RECVRETOPTS:
                case IP_RECVDSTADDR:
                case IP_RECVIF:
                case IP_RECVTTL:
                        error = sockopt_getint(sopt, &optval);
                        if (error)
                                break;

                        switch (sopt->sopt_name) {
                        case IP_TOS:
                                inp->inp_ip.ip_tos = optval;
                                break;

                        case IP_TTL:
                                inp->inp_ip.ip_ttl = optval;
                                break;

                        case IP_MINTTL:
                                if (optval > 0 && optval <= MAXTTL)
                                        inp->inp_ip_minttl = optval;
                                else
                                        error = EINVAL;
                                break;
#define OPTSET(bit) \
        if (optval) \
                inp->inp_flags |= bit; \
        else \
                inp->inp_flags &= ~bit;

                        case IP_RECVOPTS:
                                OPTSET(INP_RECVOPTS);
                                break;

                        case IP_RECVRETOPTS:
                                OPTSET(INP_RECVRETOPTS);
                                break;

                        case IP_RECVDSTADDR:
                                OPTSET(INP_RECVDSTADDR);
                                break;

                        case IP_RECVIF:
                                OPTSET(INP_RECVIF);
                                break;

                        case IP_RECVTTL:
                                OPTSET(INP_RECVTTL);
                                break;
                        }
                break;
#undef OPTSET

                case IP_MULTICAST_IF:
                case IP_MULTICAST_TTL:
                case IP_MULTICAST_LOOP:
                case IP_ADD_MEMBERSHIP:
                case IP_DROP_MEMBERSHIP:
                        error = ip_setmoptions(&inp->inp_moptions, sopt);
                        break;

                case IP_PORTRANGE:
                        error = sockopt_getint(sopt, &optval);
                        if (error)
                                break;

                        /* INP_LOCK(inp); */
                        switch (optval) {
                        case IP_PORTRANGE_DEFAULT:
                        case IP_PORTRANGE_HIGH:
                                inp->inp_flags &= ~(INP_LOWPORT);
                                break;

                        case IP_PORTRANGE_LOW:
                                inp->inp_flags |= INP_LOWPORT;
                                break;

                        default:
                                error = EINVAL;
                                break;
                        }
                        /* INP_UNLOCK(inp); */
                        break;

#if defined(IPSEC) || defined(FAST_IPSEC)
                case IP_IPSEC_POLICY:
                    {
                        error = ipsec4_set_policy(inp, sopt->sopt_name,
                            sopt->sopt_data, sopt->sopt_size, l->l_cred);
                        break;
                    }
#endif /*IPSEC*/

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;

        case PRCO_GETOPT:
                switch (sopt->sopt_name) {
                case IP_OPTIONS:
                case IP_RETOPTS:
                        if (inp->inp_options) {
                                struct mbuf *m;

                                m = m_copym(inp->inp_options, 0, M_COPYALL,
                                    M_DONTWAIT);
                                if (m == NULL) {
                                        error = ENOBUFS;
                                        break;
                                }

                                error = sockopt_setmbuf(sopt, m);
                        }
                        break;

                case IP_TOS:
                case IP_TTL:
                case IP_MINTTL:
                case IP_RECVOPTS:
                case IP_RECVRETOPTS:
                case IP_RECVDSTADDR:
                case IP_RECVIF:
                case IP_RECVTTL:
                case IP_ERRORMTU:
                        switch (sopt->sopt_name) {
                        case IP_TOS:
                                optval = inp->inp_ip.ip_tos;
                                break;

                        case IP_TTL:
                                optval = inp->inp_ip.ip_ttl;
                                break;

                        case IP_MINTTL:
                                optval = inp->inp_ip_minttl;
                                break;

                        case IP_ERRORMTU:
                                optval = inp->inp_errormtu;
                                break;

#define OPTBIT(bit)     (inp->inp_flags & bit ? 1 : 0)

                        case IP_RECVOPTS:
                                optval = OPTBIT(INP_RECVOPTS);
                                break;

                        case IP_RECVRETOPTS:
                                optval = OPTBIT(INP_RECVRETOPTS);
                                break;

                        case IP_RECVDSTADDR:
                                optval = OPTBIT(INP_RECVDSTADDR);
                                break;

                        case IP_RECVIF:
                                optval = OPTBIT(INP_RECVIF);
                                break;

                        case IP_RECVTTL:
                                optval = OPTBIT(INP_RECVTTL);
                                break;
                        }
                        error = sockopt_setint(sopt, optval);
                        break;

#if 0   /* defined(IPSEC) || defined(FAST_IPSEC) */
                case IP_IPSEC_POLICY:
                {
                        struct mbuf *m = NULL;

                        /* XXX this will return EINVAL as sopt is empty */
                        error = ipsec4_get_policy(inp, sopt->sopt_data,
                            sopt->sopt_size, &m);
                        if (error == 0)
                                error = sockopt_setmbuf(sopt, m);
                        break;
                }
#endif /*IPSEC*/

                case IP_MULTICAST_IF:
                case IP_MULTICAST_TTL:
                case IP_MULTICAST_LOOP:
                case IP_ADD_MEMBERSHIP:
                case IP_DROP_MEMBERSHIP:
                        error = ip_getmoptions(inp->inp_moptions, sopt);
                        break;

                case IP_PORTRANGE:
                        if (inp->inp_flags & INP_LOWPORT)
                                optval = IP_PORTRANGE_LOW;
                        else
                                optval = IP_PORTRANGE_DEFAULT;

                        error = sockopt_setint(sopt, optval);

                        break;

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;
        }
        return (error);
}

/*
 * Set up IP options in pcb for insertion in output packets.
 * Store in mbuf with pointer in pcbopt, adding pseudo-option
 * with destination address if source routed.
 */
int
ip_pcbopts(struct mbuf **pcbopt, const struct sockopt *sopt)
{
        struct mbuf *m;
        const u_char *cp;
        u_char *dp;
        int cnt;
        uint8_t optval, olen, offset;

        /* turn off any old options */
        if (*pcbopt)
                (void)m_free(*pcbopt);
        *pcbopt = NULL;

        cp = sopt->sopt_data;
        cnt = sopt->sopt_size;

        if (cnt == 0)
                return (0);     /* Only turning off any previous options */

#ifndef __vax__
        if (cnt % sizeof(int32_t))
                return (EINVAL);
#endif

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

        dp = mtod(m, u_char *);
        memset(dp, 0, sizeof(struct in_addr));
        dp += sizeof(struct in_addr);
        m->m_len = sizeof(struct in_addr);

        /*
         * IP option list according to RFC791. Each option is of the form
         *
         *      [optval] [olen] [(olen - 2) data bytes]
         *
         * we validate the list and copy options to an mbuf for prepending
         * to data packets. The IP first-hop destination address will be
         * stored before actual options and is zero if unset.
         */
        while (cnt > 0) {
                optval = cp[IPOPT_OPTVAL];

                if (optval == IPOPT_EOL || optval == IPOPT_NOP) {
                        olen = 1;
                } else {
                        if (cnt < IPOPT_OLEN + 1)
                                goto bad;

                        olen = cp[IPOPT_OLEN];
                        if (olen < IPOPT_OLEN + 1 || olen > cnt)
                                goto bad;
                }

                if (optval == IPOPT_LSRR || optval == IPOPT_SSRR) {
                        /*
                         * user process specifies route as:
                         *      ->A->B->C->D
                         * D must be our final destination (but we can't
                         * check that since we may not have connected yet).
                         * A is first hop destination, which doesn't appear in
                         * actual IP option, but is stored before the options.
                         */
                        if (olen < IPOPT_OFFSET + 1 + sizeof(struct in_addr))
                                goto bad;

                        offset = cp[IPOPT_OFFSET];
                        memcpy(mtod(m, u_char *), cp + IPOPT_OFFSET + 1,
                            sizeof(struct in_addr));

                        cp += sizeof(struct in_addr);
                        cnt -= sizeof(struct in_addr);
                        olen -= sizeof(struct in_addr);

                        if (m->m_len + olen > MAX_IPOPTLEN + sizeof(struct in_addr))
                                goto bad;

                        memcpy(dp, cp, olen);
                        dp[IPOPT_OPTVAL] = optval;
                        dp[IPOPT_OLEN] = olen;
                        dp[IPOPT_OFFSET] = offset;
                        break;
                } else {
                        if (m->m_len + olen > MAX_IPOPTLEN + sizeof(struct in_addr))
                                goto bad;

                        memcpy(dp, cp, olen);
                        break;
                }

                dp += olen;
                m->m_len += olen;

                if (optval == IPOPT_EOL)
                        break;

                cp += olen;
                cnt -= olen;
        }

        *pcbopt = m;
        return (0);

bad:
        (void)m_free(m);
        return (EINVAL);
}

/*
 * following RFC1724 section 3.3, 0.0.0.0/8 is interpreted as interface index.
 */
static struct ifnet *
ip_multicast_if(struct in_addr *a, int *ifindexp)
{
        int ifindex;
        struct ifnet *ifp = NULL;
        struct in_ifaddr *ia;

        if (ifindexp)
                *ifindexp = 0;
        if (ntohl(a->s_addr) >> 24 == 0) {
                ifindex = ntohl(a->s_addr) & 0xffffff;
                if (ifindex < 0 || if_indexlim <= ifindex)
                        return NULL;
                ifp = ifindex2ifnet[ifindex];
                if (!ifp)
                        return NULL;
                if (ifindexp)
                        *ifindexp = ifindex;
        } else {
                LIST_FOREACH(ia, &IN_IFADDR_HASH(a->s_addr), ia_hash) {
                        if (in_hosteq(ia->ia_addr.sin_addr, *a) &&
                            (ia->ia_ifp->if_flags & IFF_MULTICAST) != 0) {
                                ifp = ia->ia_ifp;
                                break;
                        }
                }
        }
        return ifp;
}

static int
ip_getoptval(const struct sockopt *sopt, u_int8_t *val, u_int maxval)
{
        u_int tval;
        u_char cval;
        int error;

        if (sopt == NULL)
                return EINVAL;

        switch (sopt->sopt_size) {
        case sizeof(u_char):
                error = sockopt_get(sopt, &cval, sizeof(u_char));
                tval = cval;
                break;

        case sizeof(u_int):
                error = sockopt_get(sopt, &tval, sizeof(u_int));
                break;

        default:
                error = EINVAL;
        }

        if (error)
                return error;

        if (tval > maxval)
                return EINVAL;

        *val = tval;
        return 0;
}

/*
 * Set the IP multicast options in response to user setsockopt().
 */
int
ip_setmoptions(struct ip_moptions **imop, const struct sockopt *sopt)
{
        int error = 0;
        int i;
        struct in_addr addr;
        struct ip_mreq lmreq, *mreq;
        struct ifnet *ifp;
        struct ip_moptions *imo = *imop;
        int ifindex;

        if (imo == NULL) {
                /*
                 * No multicast option buffer attached to the pcb;
                 * allocate one and initialize to default values.
                 */
                imo = malloc(sizeof(*imo), M_IPMOPTS, M_NOWAIT);
                if (imo == NULL)
                        return (ENOBUFS);

                *imop = imo;
                imo->imo_multicast_ifp = NULL;
                imo->imo_multicast_addr.s_addr = INADDR_ANY;
                imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
                imo->imo_multicast_loop = IP_DEFAULT_MULTICAST_LOOP;
                imo->imo_num_memberships = 0;
        }

        switch (sopt->sopt_name) {
        case IP_MULTICAST_IF:
                /*
                 * Select the interface for outgoing multicast packets.
                 */
                error = sockopt_get(sopt, &addr, sizeof(addr));
                if (error)
                        break;

                /*
                 * INADDR_ANY is used to remove a previous selection.
                 * When no interface is selected, a default one is
                 * chosen every time a multicast packet is sent.
                 */
                if (in_nullhost(addr)) {
                        imo->imo_multicast_ifp = NULL;
                        break;
                }
                /*
                 * The selected interface is identified by its local
                 * IP address.  Find the interface and confirm that
                 * it supports multicasting.
                 */
                ifp = ip_multicast_if(&addr, &ifindex);
                if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
                        error = EADDRNOTAVAIL;
                        break;
                }
                imo->imo_multicast_ifp = ifp;
                if (ifindex)
                        imo->imo_multicast_addr = addr;
                else
                        imo->imo_multicast_addr.s_addr = INADDR_ANY;
                break;

        case IP_MULTICAST_TTL:
                /*
                 * Set the IP time-to-live for outgoing multicast packets.
                 */
                error = ip_getoptval(sopt, &imo->imo_multicast_ttl, MAXTTL);
                break;

        case IP_MULTICAST_LOOP:
                /*
                 * Set the loopback flag for outgoing multicast packets.
                 * Must be zero or one.
                 */
                error = ip_getoptval(sopt, &imo->imo_multicast_loop, 1);
                break;

        case IP_ADD_MEMBERSHIP:
                /*
                 * Add a multicast group membership.
                 * Group must be a valid IP multicast address.
                 */
                error = sockopt_get(sopt, &lmreq, sizeof(lmreq));
                if (error)
                        break;

                mreq = &lmreq;

                if (!IN_MULTICAST(mreq->imr_multiaddr.s_addr)) {
                        error = EINVAL;
                        break;
                }
                /*
                 * If no interface address was provided, use the interface of
                 * the route to the given multicast address.
                 */
                if (in_nullhost(mreq->imr_interface)) {
                        struct rtentry *rt;
                        union {
                                struct sockaddr         dst;
                                struct sockaddr_in      dst4;
                        } u;
                        struct route ro;

                        memset(&ro, 0, sizeof(ro));

                        sockaddr_in_init(&u.dst4, &mreq->imr_multiaddr, 0);
                        rtcache_setdst(&ro, &u.dst);
                        ifp = (rt = rtcache_init(&ro)) != NULL ? rt->rt_ifp
                                                                : NULL;
                        rtcache_free(&ro);
                } else {
                        ifp = ip_multicast_if(&mreq->imr_interface, NULL);
                }
                /*
                 * See if we found an interface, and confirm that it
                 * supports multicast.
                 */
                if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
                        error = EADDRNOTAVAIL;
                        break;
                }
                /*
                 * See if the membership already exists or if all the
                 * membership slots are full.
                 */
                for (i = 0; i < imo->imo_num_memberships; ++i) {
                        if (imo->imo_membership[i]->inm_ifp == ifp &&
                            in_hosteq(imo->imo_membership[i]->inm_addr,
                                      mreq->imr_multiaddr))
                                break;
                }
                if (i < imo->imo_num_memberships) {
                        error = EADDRINUSE;
                        break;
                }
                if (i == IP_MAX_MEMBERSHIPS) {
                        error = ETOOMANYREFS;
                        break;
                }
                /*
                 * Everything looks good; add a new record to the multicast
                 * address list for the given interface.
                 */
                if ((imo->imo_membership[i] =
                    in_addmulti(&mreq->imr_multiaddr, ifp)) == NULL) {
                        error = ENOBUFS;
                        break;
                }
                ++imo->imo_num_memberships;
                break;

        case IP_DROP_MEMBERSHIP:
                /*
                 * Drop a multicast group membership.
                 * Group must be a valid IP multicast address.
                 */
                error = sockopt_get(sopt, &lmreq, sizeof(lmreq));
                if (error)
                        break;

                mreq = &lmreq;

                if (!IN_MULTICAST(mreq->imr_multiaddr.s_addr)) {
                        error = EINVAL;
                        break;
                }
                /*
                 * If an interface address was specified, get a pointer
                 * to its ifnet structure.
                 */
                if (in_nullhost(mreq->imr_interface))
                        ifp = NULL;
                else {
                        ifp = ip_multicast_if(&mreq->imr_interface, NULL);
                        if (ifp == NULL) {
                                error = EADDRNOTAVAIL;
                                break;
                        }
                }
                /*
                 * Find the membership in the membership array.
                 */
                for (i = 0; i < imo->imo_num_memberships; ++i) {
                        if ((ifp == NULL ||
                             imo->imo_membership[i]->inm_ifp == ifp) &&
                             in_hosteq(imo->imo_membership[i]->inm_addr,
                                       mreq->imr_multiaddr))
                                break;
                }
                if (i == imo->imo_num_memberships) {
                        error = EADDRNOTAVAIL;
                        break;
                }
                /*
                 * Give up the multicast address record to which the
                 * membership points.
                 */
                in_delmulti(imo->imo_membership[i]);
                /*
                 * Remove the gap in the membership array.
                 */
                for (++i; i < imo->imo_num_memberships; ++i)
                        imo->imo_membership[i-1] = imo->imo_membership[i];
                --imo->imo_num_memberships;
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        /*
         * If all options have default values, no need to keep the mbuf.
         */
        if (imo->imo_multicast_ifp == NULL &&
            imo->imo_multicast_ttl == IP_DEFAULT_MULTICAST_TTL &&
            imo->imo_multicast_loop == IP_DEFAULT_MULTICAST_LOOP &&
            imo->imo_num_memberships == 0) {
                free(*imop, M_IPMOPTS);
                *imop = NULL;
        }

        return (error);
}

/*
 * Return the IP multicast options in response to user getsockopt().
 */
int
ip_getmoptions(struct ip_moptions *imo, struct sockopt *sopt)
{
        struct in_addr addr;
        struct in_ifaddr *ia;
        int error;
        uint8_t optval;

        error = 0;

        switch (sopt->sopt_name) {
        case IP_MULTICAST_IF:
                if (imo == NULL || imo->imo_multicast_ifp == NULL)
                        addr = zeroin_addr;
                else if (imo->imo_multicast_addr.s_addr) {
                        /* return the value user has set */
                        addr = imo->imo_multicast_addr;
                } else {
                        IFP_TO_IA(imo->imo_multicast_ifp, ia);
                        addr = ia ? ia->ia_addr.sin_addr : zeroin_addr;
                }
                error = sockopt_set(sopt, &addr, sizeof(addr));
                break;

        case IP_MULTICAST_TTL:
                optval = imo ? imo->imo_multicast_ttl
                             : IP_DEFAULT_MULTICAST_TTL;

                error = sockopt_set(sopt, &optval, sizeof(optval));
                break;

        case IP_MULTICAST_LOOP:
                optval = imo ? imo->imo_multicast_loop
                             : IP_DEFAULT_MULTICAST_LOOP;

                error = sockopt_set(sopt, &optval, sizeof(optval));
                break;

        default:
                error = EOPNOTSUPP;
        }

        return (error);
}

/*
 * Discard the IP multicast options.
 */
void
ip_freemoptions(struct ip_moptions *imo)
{
        int i;

        if (imo != NULL) {
                for (i = 0; i < imo->imo_num_memberships; ++i)
                        in_delmulti(imo->imo_membership[i]);
                free(imo, M_IPMOPTS);
        }
}

/*
 * Routine called from ip_output() to loop back a copy of an IP multicast
 * packet to the input queue of a specified interface.  Note that this
 * calls the output routine of the loopback "driver", but with an interface
 * pointer that might NOT be lo0ifp -- easier than replicating that code here.
 */
static void
ip_mloopback(struct ifnet *ifp, struct mbuf *m, const struct sockaddr_in *dst)
{
        struct ip *ip;
        struct mbuf *copym;

        copym = m_copypacket(m, M_DONTWAIT);
        if (copym != NULL
         && (copym->m_flags & M_EXT || copym->m_len < sizeof(struct ip)))
                copym = m_pullup(copym, sizeof(struct ip));
        if (copym == NULL)
                return;
        /*
         * We don't bother to fragment if the IP length is greater
         * than the interface's MTU.  Can this possibly matter?
         */
        ip = mtod(copym, struct ip *);

        if (copym->m_pkthdr.csum_flags & (M_CSUM_TCPv4|M_CSUM_UDPv4)) {
                in_delayed_cksum(copym);
                copym->m_pkthdr.csum_flags &=
                    ~(M_CSUM_TCPv4|M_CSUM_UDPv4);
        }

        ip->ip_sum = 0;
        ip->ip_sum = in_cksum(copym, ip->ip_hl << 2);
        (void)looutput(ifp, copym, sintocsa(dst), NULL);
}