/*
 * 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
 * $FreeBSD: src/sys/netinet/ip_output.c,v 1.99.2.37 2003/04/15 06:44:45 silby Exp $
 */

#define _IP_VHL

#include "opt_ipdn.h"
#include "opt_ipdivert.h"
#include "opt_mbuf_stress_test.h"
#include "opt_mpls.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/proc.h>
#include <sys/caps.h>
#include <sys/sysctl.h>
#include <sys/in_cksum.h>
#include <sys/lock.h>

#include <sys/thread2.h>
#include <sys/mplock2.h>
#include <sys/msgport2.h>

#include <net/if.h>
#include <net/netisr.h>
#include <net/pfil.h>
#include <net/route.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 <netproto/mpls/mpls_var.h>

static MALLOC_DEFINE(M_IPMOPTS, "ip_moptions", "internet multicast options");

#include <net/ipfw/ip_fw.h>
#include <net/dummynet/ip_dummynet.h>

#define print_ip(x, a, y)        kprintf("%s %d.%d.%d.%d%s",\
                                x, (ntohl(a.s_addr)>>24)&0xFF,\
                                  (ntohl(a.s_addr)>>16)&0xFF,\
                                  (ntohl(a.s_addr)>>8)&0xFF,\
                                  (ntohl(a.s_addr))&0xFF, y);

u_short ip_id;

#ifdef MBUF_STRESS_TEST
int mbuf_frag_size = 0;
SYSCTL_INT(_net_inet_ip, OID_AUTO, mbuf_frag_size, CTLFLAG_RW,
        &mbuf_frag_size, 0, "Fragment outgoing mbufs to this size");
#endif

static int ip_do_rfc6864 = 1;
SYSCTL_INT(_net_inet_ip, OID_AUTO, rfc6864, CTLFLAG_RW, &ip_do_rfc6864, 0,
    "Don't generate IP ID for DF IP datagrams");

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 *, struct sockaddr_in *, int);
static int      ip_getmoptions
        (struct sockopt *, struct ip_moptions *);
static int      ip_pcbopts(int, struct mbuf **, struct mbuf *);
static int      ip_setmoptions
        (struct sockopt *, struct ip_moptions **);

int     ip_optcopy(struct ip *, struct ip *);

extern  struct protosw inetsw[];

static int
ip_localforward(struct mbuf *m, const struct sockaddr_in *dst, int hlen)
{
        struct in_ifaddr_container *iac;

        /*
         * We need to figure out if we have been forwarded to a local
         * socket.  If so, then we should somehow "loop back" to
         * ip_input(), and get directed to the PCB as if we had received
         * this packet.  This is because it may be difficult to identify
         * the packets you want to forward until they are being output
         * and have selected an interface (e.g. locally initiated
         * packets).  If we used the loopback inteface, we would not be
         * able to control what happens as the packet runs through
         * ip_input() as it is done through a ISR.
         */
        LIST_FOREACH(iac, INADDR_HASH(dst->sin_addr.s_addr), ia_hash) {
                /*
                 * If the addr to forward to is one of ours, we pretend
                 * to be the destination for this packet.
                 */
                if (IA_SIN(iac->ia)->sin_addr.s_addr == dst->sin_addr.s_addr)
                        break;
        }
        if (iac != NULL) {
                if (m->m_pkthdr.rcvif == NULL)
                        m->m_pkthdr.rcvif = loif;
                if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
                        m->m_pkthdr.csum_flags |= CSUM_DATA_VALID |
                                                  CSUM_PSEUDO_HDR;
                        m->m_pkthdr.csum_data = 0xffff;
                }
                m->m_pkthdr.csum_flags |= CSUM_IP_CHECKED | CSUM_IP_VALID;

                /*
                 * Make sure that the IP header is in one mbuf,
                 * required by ip_input
                 */
                if (m->m_len < hlen) {
                        m = m_pullup(m, hlen);
                        if (m == NULL) {
                                /* The packet was freed; we are done */
                                return 1;
                        }
                }
                ip_input(m);

                return 1; /* The packet gets forwarded locally */
        }
        return 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 mbuf *opt, struct route *ro,
          int flags, struct ip_moptions *imo, struct inpcb *inp)
{
        struct ip *ip;
        struct ifnet *ifp = NULL;       /* keep compiler happy */
        struct mbuf *m;
        int hlen = sizeof(struct ip);
        int len, error = 0;
        struct sockaddr_in *dst = NULL; /* keep compiler happy */
        struct in_ifaddr *ia = NULL;
        int isbroadcast, sw_csum;
        struct in_addr pkt_dst;
        struct route iproute;
        struct m_tag *mtag;
        struct sockaddr_in *next_hop = NULL;
        int src_was_INADDR_ANY = 0;     /* as the name says... */

        ASSERT_NETISR_NCPUS(mycpuid);

        m = m0;
        M_ASSERTPKTHDR(m);

        if (ro == NULL) {
                ro = &iproute;
                bzero(ro, sizeof *ro);
        } else if (ro->ro_rt != NULL && ro->ro_rt->rt_cpuid != mycpuid) {
                if (flags & IP_DEBUGROUTE) {
                        panic("ip_output: rt rt_cpuid %d accessed on cpu %d\n",
                            ro->ro_rt->rt_cpuid, mycpuid);
                }

                /*
                 * XXX
                 * If the cached rtentry's owner CPU is not the current CPU,
                 * then don't touch the cached rtentry (remote free is too
                 * expensive in this context); just relocate the route.
                 */
                ro = &iproute;
                bzero(ro, sizeof *ro);
        }

        if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) {
                /* Next hop */
                mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
                KKASSERT(mtag != NULL);
                next_hop = m_tag_data(mtag);
        }

        if (m->m_pkthdr.fw_flags & DUMMYNET_MBUF_TAGGED) {
                struct dn_pkt *dn_pkt;

                /* Extract info from dummynet tag */
                mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
                KKASSERT(mtag != NULL);
                dn_pkt = m_tag_data(mtag);

                /*
                 * The packet was already tagged, so part of the
                 * processing was already done, and we need to go down.
                 * Get the calculated parameters from the tag.
                 */
                ifp = dn_pkt->ifp;

                KKASSERT(ro == &iproute);
                *ro = dn_pkt->ro; /* structure copy */
                KKASSERT(ro->ro_rt == NULL || ro->ro_rt->rt_cpuid == mycpuid);

                dst = dn_pkt->dn_dst;
                if (dst == (struct sockaddr_in *)&(dn_pkt->ro.ro_dst)) {
                        /* If 'dst' points into dummynet tag, adjust it */
                        dst = (struct sockaddr_in *)&(ro->ro_dst);
                }

                ip = mtod(m, struct ip *);
                hlen = IP_VHL_HL(ip->ip_vhl) << 2 ;
                if (ro->ro_rt)
                        ia = ifatoia(ro->ro_rt->rt_ifa);
                goto sendit;
        }

        if (opt) {
                len = 0;
                m = ip_insertoptions(m, opt, &len);
                if (len != 0)
                        hlen = len;
        }
        ip = mtod(m, struct ip *);

        /*
         * Fill in IP header.
         */
        if (!(flags & (IP_FORWARDING|IP_RAWOUTPUT))) {
                ip->ip_vhl = IP_MAKE_VHL(IPVERSION, hlen >> 2);
                ip->ip_off &= htons(IP_DF);
                if (ip_do_rfc6864 && (ip->ip_off & htons(IP_DF)))
                        ip->ip_id = 0;
                else
                        ip->ip_id = ip_newid();
                ipstat.ips_localout++;
        } else {
                hlen = IP_VHL_HL(ip->ip_vhl) << 2;
        }

reroute:
        pkt_dst = next_hop ? next_hop->sin_addr : ip->ip_dst;

        dst = (struct sockaddr_in *)&ro->ro_dst;
        /*
         * 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 (ro->ro_rt &&
            (!(ro->ro_rt->rt_flags & RTF_UP) ||
             dst->sin_family != AF_INET ||
             dst->sin_addr.s_addr != pkt_dst.s_addr)) {
                rtfree(ro->ro_rt);
                ro->ro_rt = NULL;
        }
        if (ro->ro_rt == NULL) {
                bzero(dst, sizeof *dst);
                dst->sin_family = AF_INET;
                dst->sin_len = sizeof *dst;
                dst->sin_addr = pkt_dst;
        }
        /*
         * If routing to interface only,
         * short circuit routing lookup.
         */
        if (flags & IP_ROUTETOIF) {
                if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
                    (ia = ifatoia(ifa_ifwithnet(sintosa(dst)))) == NULL) {
                        ipstat.ips_noroute++;
                        error = ENETUNREACH;
                        goto bad;
                }
                ifp = ia->ia_ifp;
                ip->ip_ttl = 1;
                isbroadcast = in_broadcast(dst->sin_addr, ifp);
        } else if (IN_MULTICAST(ntohl(pkt_dst.s_addr)) &&
                   imo != NULL && imo->imo_multicast_ifp != NULL) {
                /*
                 * Bypass the normal routing lookup for multicast
                 * packets if the interface is specified.
                 */
                ifp = imo->imo_multicast_ifp;
                ia = IFP_TO_IA(ifp);
                isbroadcast = 0;        /* fool gcc */
        } else {
                /*
                 * If this is the case, we probably don't want to allocate
                 * a protocol-cloned route since we didn't get one from the
                 * ULP.  This lets TCP do its thing, while not burdening
                 * forwarding or ICMP with the overhead of cloning a route.
                 * Of course, we still want to do any cloning requested by
                 * the link layer, as this is probably required in all cases
                 * for correct operation (as it is for ARP).
                 */
                if (ro->ro_rt == NULL)
                        rtalloc_ign(ro, RTF_PRCLONING);
                if (ro->ro_rt == NULL) {
                        ipstat.ips_noroute++;
                        error = EHOSTUNREACH;
                        goto bad;
                }
                ia = ifatoia(ro->ro_rt->rt_ifa);
                ifp = ro->ro_rt->rt_ifp;
                ro->ro_rt->rt_use++;
                if (ro->ro_rt->rt_flags & RTF_GATEWAY)
                        dst = (struct sockaddr_in *)ro->ro_rt->rt_gateway;
                if (ro->ro_rt->rt_flags & RTF_HOST)
                        isbroadcast = (ro->ro_rt->rt_flags & RTF_BROADCAST);
                else
                        isbroadcast = in_broadcast(dst->sin_addr, ifp);
        }
        if (IN_MULTICAST(ntohl(pkt_dst.s_addr))) {
                m->m_flags |= M_MCAST;
                /*
                 * IP destination address is multicast.  Make sure "dst"
                 * still points to the address in "ro".  (It may have been
                 * changed to point to a gateway address, above.)
                 */
                dst = (struct sockaddr_in *)&ro->ro_dst;
                /*
                 * See if the caller provided any multicast options
                 */
                if (imo != NULL) {
                        ip->ip_ttl = imo->imo_multicast_ttl;
                        if (imo->imo_multicast_vif != -1) {
                                ip->ip_src.s_addr =
                                    ip_mcast_src ?
                                    ip_mcast_src(imo->imo_multicast_vif) :
                                    INADDR_ANY;
                        }
                } else {
                        ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
                }
                /*
                 * Confirm that the outgoing interface supports multicast.
                 */
                if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
                        if (!(ifp->if_flags & IFF_MULTICAST)) {
                                ipstat.ips_noroute++;
                                error = ENETUNREACH;
                                goto bad;
                        }
                }
                /*
                 * If source address not specified yet, use address of the
                 * outgoing interface.  In case, keep note we did that, so
                 * if the the firewall changes the next-hop causing the
                 * output interface to change, we can fix that.
                 */
                if (ip->ip_src.s_addr == INADDR_ANY || src_was_INADDR_ANY) {
                        /* Interface may have no addresses. */
                        if (ia != NULL) {
                                ip->ip_src = IA_SIN(ia)->sin_addr;
                                src_was_INADDR_ANY = 1;
                        }
                }

                if (ip->ip_src.s_addr != INADDR_ANY) {
                        struct in_multi *inm;

                        inm = IN_LOOKUP_MULTI(&pkt_dst, ifp);
                        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, dst, hlen);
                        } 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.
                                 */
                                if (ip_mrouter && !(flags & IP_FORWARDING)) {
                                        /*
                                         * If rsvp daemon is not running, do
                                         * not set ip_moptions. This ensures
                                         * that the packet is multicast and
                                         * not just sent down one link as
                                         * prescribed by rsvpd.
                                         */
                                        if (!rsvp_on)
                                                imo = NULL;
                                        if (ip_mforward) {
                                                get_mplock();
                                                if (ip_mforward(ip, ifp,
                                                    m, imo) != 0) {
                                                        m_freem(m);
                                                        rel_mplock();
                                                        goto done;
                                                }
                                                rel_mplock();
                                        }
                                }
                        }
                }

                /*
                 * 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) {
                        m_freem(m);
                        goto done;
                }

                goto sendit;
        } else {
                m->m_flags &= ~M_MCAST;
        }

        /*
         * If the source address is not specified yet, use the address
         * of the outgoing interface.  In case, keep note we did that,
         * so if the firewall changes the next-hop causing the output
         * interface to change, we can fix that.
         */
        if (ip->ip_src.s_addr == INADDR_ANY || src_was_INADDR_ANY) {
                /* Interface may have no addresses. */
                if (ia != NULL) {
                        ip->ip_src = IA_SIN(ia)->sin_addr;
                        src_was_INADDR_ANY = 1;
                }
        }

        /*
         * Look for broadcast address and
         * verify user is allowed to send
         * such a packet.
         */
        if (isbroadcast) {
                if (!(ifp->if_flags & IFF_BROADCAST)) {
                        error = EADDRNOTAVAIL;
                        goto bad;
                }
                if (!(flags & IP_ALLOWBROADCAST)) {
                        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:

        /* We are already being fwd'd from a firewall. */
        if (next_hop != NULL)
                goto pass;

        /* No pfil hooks */
        if (!pfil_has_hooks(&inet_pfil_hook)) {
                if (m->m_pkthdr.fw_flags & DUMMYNET_MBUF_TAGGED) {
                        /*
                         * Strip dummynet tags from stranded packets
                         */
                        mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
                        KKASSERT(mtag != NULL);
                        m_tag_delete(m, mtag);
                        m->m_pkthdr.fw_flags &= ~DUMMYNET_MBUF_TAGGED;
                }
                goto pass;
        }

        /*
         * IpHack's section.
         * - Xlate: translate packet's addr/port (NAT).
         * - Firewall: deny/allow/etc.
         * - Wrap: fake packet's addr/port <unimpl.>
         * - Encapsulate: put it in another IP and send out. <unimp.>
         */

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

        if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) {
                /*
                 * Check dst to make sure it is directly reachable on the
                 * interface we previously thought it was.
                 * If it isn't (which may be likely in some situations) we have
                 * to re-route it (ie, find a route for the next-hop and the
                 * associated interface) and set them here. This is nested
                 * forwarding which in most cases is undesirable, except where
                 * such control is nigh impossible. So we do it here.
                 * And I'm babbling.
                 */
                mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
                KKASSERT(mtag != NULL);
                next_hop = m_tag_data(mtag);

                /*
                 * Try local forwarding first
                 */
                if (ip_localforward(m, next_hop, hlen))
                        goto done;

                /*
                 * Relocate the route based on next_hop.
                 * If the current route is inp's cache, keep it untouched.
                 */
                if (ro == &iproute && ro->ro_rt != NULL) {
                        RTFREE(ro->ro_rt);
                        ro->ro_rt = NULL;
                }
                ro = &iproute;
                bzero(ro, sizeof *ro);

                /*
                 * Forwarding to broadcast address is not allowed.
                 * XXX Should we follow IP_ROUTETOIF?
                 */
                flags &= ~(IP_ALLOWBROADCAST | IP_ROUTETOIF);

                /* We are doing forwarding now */
                flags |= IP_FORWARDING;

                goto reroute;
        }

        if (m->m_pkthdr.fw_flags & DUMMYNET_MBUF_TAGGED) {
                struct dn_pkt *dn_pkt;

                mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
                KKASSERT(mtag != NULL);
                dn_pkt = m_tag_data(mtag);

                /*
                 * Under certain cases it is not possible to recalculate
                 * 'ro' and 'dst', let alone 'flags', so just save them in
                 * dummynet tag and avoid the possible wrong reculcalation
                 * when we come back to ip_output() again.
                 *
                 * All other parameters have been already used and so they
                 * are not needed anymore.
                 * XXX if the ifp is deleted while a pkt is in dummynet,
                 * we are in trouble! (TODO use ifnet_detach_event)
                 *
                 * We need to copy *ro because for ICMP pkts (and maybe
                 * others) the caller passed a pointer into the stack;
                 * dst might also be a pointer into *ro so it needs to
                 * be updated.
                 */
                dn_pkt->ro = *ro;
                if (ro->ro_rt)
                        ro->ro_rt->rt_refcnt++;
                if (dst == (struct sockaddr_in *)&ro->ro_dst) {
                        /* 'dst' points into 'ro' */
                        dst = (struct sockaddr_in *)&(dn_pkt->ro.ro_dst);
                }
                dn_pkt->dn_dst = dst;
                dn_pkt->flags = flags;

                ip_dn_queue(m);
                goto done;
        }

        if (m->m_pkthdr.fw_flags & IPFW_MBUF_CONTINUE) {
                /* ipfw was disabled/unloaded. */
                m_freem(m);
                goto done;
        }
pass:
        /* 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)) {
                        ipstat.ips_badaddr++;
                        error = EADDRNOTAVAIL;
                        goto bad;
                }
        }
        if (ip->ip_src.s_addr == INADDR_ANY ||
            IN_MULTICAST(ntohl(ip->ip_src.s_addr))) {
                ipstat.ips_badaddr++;
                error = EADDRNOTAVAIL;
                goto bad;
        }

        if ((m->m_pkthdr.csum_flags & CSUM_TSO) == 0) {
                m->m_pkthdr.csum_flags |= CSUM_IP;
                sw_csum = m->m_pkthdr.csum_flags & ~ifp->if_hwassist;
                if (sw_csum & CSUM_DELAY_DATA) {
                        in_delayed_cksum(m);
                        sw_csum &= ~CSUM_DELAY_DATA;
                }
                m->m_pkthdr.csum_flags &= ifp->if_hwassist;
        } else {
                sw_csum = 0;
        }
        m->m_pkthdr.csum_iphlen = hlen;

        /*
         * If small enough for interface, or the interface will take
         * care of the fragmentation or segmentation for us, can just
         * send directly.
         */
        if (ntohs(ip->ip_len) <= ifp->if_mtu ||
            ((ifp->if_hwassist & CSUM_FRAGMENT) &&
              !(ip->ip_off & htons(IP_DF))) ||
            (m->m_pkthdr.csum_flags & CSUM_TSO))
        {
                ip->ip_sum = 0;
                if (sw_csum & CSUM_DELAY_IP) {
                        if (ip->ip_vhl == IP_VHL_BORING)
                                ip->ip_sum = in_cksum_hdr(ip);
                        else
                                ip->ip_sum = in_cksum(m, hlen);
                }

                /* Record statistics for this interface address. */
                if (!(flags & IP_FORWARDING) && ia) {
                        IFA_STAT_INC(&ia->ia_ifa, opackets, 1);
                        IFA_STAT_INC(&ia->ia_ifa, obytes, m->m_pkthdr.len);
                }

#ifdef MBUF_STRESS_TEST
                if (mbuf_frag_size && m->m_pkthdr.len > mbuf_frag_size) {
                        struct mbuf *m1, *m2;
                        int length, tmp;

                        tmp = length = m->m_pkthdr.len;

                        while ((length -= mbuf_frag_size) >= 1) {
                                m1 = m_split(m, length, M_NOWAIT);
                                if (m1 == NULL)
                                        break;
                                m2 = m;
                                while (m2->m_next != NULL)
                                        m2 = m2->m_next;
                                m2->m_next = m1;
                        }
                        m->m_pkthdr.len = tmp;
                }
#endif

#ifdef MPLS
                if (!mpls_output_process(m, ro->ro_rt))
                        goto done;
#endif
                error = ifp->if_output(ifp, m, (struct sockaddr *)dst,
                                       ro->ro_rt);
                goto done;
        }

        if (ip->ip_off & htons(IP_DF)) {
                error = EMSGSIZE;
                /*
                 * This case can happen if the user changed the MTU
                 * of an interface after enabling IP on it.  Because
                 * most netifs don't keep track of routes pointing to
                 * them, there is no way for one to update all its
                 * routes when the MTU is changed.
                 */
                if ((ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) &&
                    !(ro->ro_rt->rt_rmx.rmx_locks & RTV_MTU) &&
                    (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)) {
                        ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
                }
                ipstat.ips_cantfrag++;
                goto bad;
        }

        /*
         * Too large for interface; fragment if possible. If successful,
         * on return, m will point to a list of packets to be sent.
         */
        error = ip_fragment(ip, &m, ifp->if_mtu, ifp->if_hwassist, sw_csum);
        if (error)
                goto bad;
        for (; m; m = m0) {
                m0 = m->m_nextpkt;
                m->m_nextpkt = NULL;
                if (error == 0) {
                        /* Record statistics for this interface address. */
                        if (ia != NULL) {
                                IFA_STAT_INC(&ia->ia_ifa, opackets, 1);
                                IFA_STAT_INC(&ia->ia_ifa, obytes,
                                    m->m_pkthdr.len);
                        }
#ifdef MPLS
                        if (!mpls_output_process(m, ro->ro_rt))
                                continue;
#endif
                        error = ifp->if_output(ifp, m, (struct sockaddr *)dst,
                                               ro->ro_rt);
                } else {
                        m_freem(m);
                }
        }

        if (error == 0)
                ipstat.ips_fragmented++;

done:
        if (ro == &iproute && ro->ro_rt != NULL) {
                RTFREE(ro->ro_rt);
                ro->ro_rt = NULL;
        }
        return (error);
bad:
        m_freem(m);
        goto done;
}

/*
 * Create a chain of fragments which fit the given mtu. m_frag points to the
 * mbuf to be fragmented; on return it points to the chain with the fragments.
 * Return 0 if no error. If error, m_frag may contain a partially built
 * chain of fragments that should be freed by the caller.
 *
 * if_hwassist_flags is the hw offload capabilities (see if_data.ifi_hwassist)
 * sw_csum contains the delayed checksums flags (e.g., CSUM_DELAY_IP).
 */
int
ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
            u_long if_hwassist_flags, int sw_csum)
{
        int error = 0;
        int hlen = IP_VHL_HL(ip->ip_vhl) << 2;
        int len = (mtu - hlen) & ~7;    /* size of payload in each fragment */
        int off;
        struct mbuf *m0 = *m_frag;      /* the original packet          */
        int firstlen;
        struct mbuf **mnext;
        int nfrags;

        if (ip->ip_off & htons(IP_DF)) { /* Fragmentation not allowed */
                ipstat.ips_cantfrag++;
                return EMSGSIZE;
        }

        /*
         * Must be able to put at least 8 bytes per fragment.
         */
        if (len < 8)
                return EMSGSIZE;

        /*
         * If the interface will not calculate checksums on
         * fragmented packets, then do it here.
         */
        if ((m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA) &&
            !(if_hwassist_flags & CSUM_IP_FRAGS)) {
                in_delayed_cksum(m0);
                m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
        }

        if (len > PAGE_SIZE) {
                /*
                 * Fragment large datagrams such that each segment
                 * contains a multiple of PAGE_SIZE amount of data,
                 * plus headers. This enables a receiver to perform
                 * page-flipping zero-copy optimizations.
                 *
                 * XXX When does this help given that sender and receiver
                 * could have different page sizes, and also mtu could
                 * be less than the receiver's page size ?
                 */
                int newlen;
                struct mbuf *m;

                for (m = m0, off = 0; m && (off+m->m_len) <= mtu; m = m->m_next)
                        off += m->m_len;

                /*
                 * firstlen (off - hlen) must be aligned on an
                 * 8-byte boundary
                 */
                if (off < hlen)
                        goto smart_frag_failure;
                off = ((off - hlen) & ~7) + hlen;
                newlen = (~PAGE_MASK) & mtu;
                if ((newlen + sizeof(struct ip)) > mtu) {
                        /* we failed, go back the default */
smart_frag_failure:
                        newlen = len;
                        off = hlen + len;
                }
                len = newlen;

        } else {
                off = hlen + len;
        }

        firstlen = off - hlen;
        mnext = &m0->m_nextpkt;         /* pointer to next packet */

        /*
         * Loop through length of segment after first fragment,
         * make new header and copy data of each part and link onto chain.
         * Here, m0 is the original packet, m is the fragment being created.
         * The fragments are linked off the m_nextpkt of the original
         * packet, which after processing serves as the first fragment.
         */
        for (nfrags = 1; off < ntohs(ip->ip_len); off += len, nfrags++) {
                struct ip *mhip;        /* ip header on the fragment */
                struct mbuf *m;
                int mhlen = sizeof(struct ip);

                MGETHDR(m, M_NOWAIT, MT_HEADER);
                if (m == NULL) {
                        error = ENOBUFS;
                        ipstat.ips_odropped++;
                        goto done;
                }
                m->m_flags |= (m0->m_flags & M_MCAST) | M_FRAG;
                /*
                 * In the first mbuf, leave room for the link header, then
                 * copy the original IP header including options. The payload
                 * goes into an additional mbuf chain returned by m_copym().
                 */
                m->m_data += max_linkhdr;
                mhip = mtod(m, struct ip *);
                *mhip = *ip;
                if (hlen > sizeof(struct ip)) {
                        mhlen = ip_optcopy(ip, mhip) + sizeof(struct ip);
                        mhip->ip_vhl = IP_MAKE_VHL(IPVERSION, mhlen >> 2);
                }
                m->m_len = mhlen;
                /* XXX do we need to add ip->ip_off below ? */
                mhip->ip_off = htons(((off - hlen) >> 3) + ntohs(ip->ip_off));
                if (off + len >= ntohs(ip->ip_len)) {   /* last fragment */
                        len = ntohs(ip->ip_len) - off;
                        m->m_flags |= M_LASTFRAG;
                } else {
                        mhip->ip_off |= htons(IP_MF);
                }
                mhip->ip_len = htons((u_short)(len + mhlen));
                m->m_next = m_copym(m0, off, len, M_NOWAIT);
                if (m->m_next == NULL) {                /* copy failed */
                        m_free(m);
                        error = ENOBUFS;        /* ??? */
                        ipstat.ips_odropped++;
                        goto done;
                }
                m->m_pkthdr.len = mhlen + len;
                m->m_pkthdr.rcvif = NULL;
                m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
                m->m_pkthdr.csum_iphlen = mhlen;
                mhip->ip_sum = 0;
                if (sw_csum & CSUM_DELAY_IP)
                        mhip->ip_sum = in_cksum(m, mhlen);
                *mnext = m;
                mnext = &m->m_nextpkt;
        }
        ipstat.ips_ofragments += nfrags;

        /* set first marker for fragment chain */
        m0->m_flags |= M_FIRSTFRAG | M_FRAG;
        m0->m_pkthdr.csum_data = nfrags;

        /*
         * Update first fragment by trimming what's been copied out
         * and updating header.
         */
        m_adj(m0, hlen + firstlen - ntohs(ip->ip_len));
        m0->m_pkthdr.len = hlen + firstlen;
        ip->ip_len = htons((u_short)m0->m_pkthdr.len);
        ip->ip_off |= htons(IP_MF);
        ip->ip_sum = 0;
        if (sw_csum & CSUM_DELAY_IP)
                ip->ip_sum = in_cksum(m0, hlen);

done:
        *m_frag = m0;
        return error;
}

void
in_delayed_cksum(struct mbuf *m)
{
        struct ip *ip;
        u_short csum, offset;

        ip = mtod(m, struct ip *);
        offset = IP_VHL_HL(ip->ip_vhl) << 2 ;
        csum = in_cksum_skip(m, ntohs(ip->ip_len), offset);
        if (m->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
                csum = 0xffff;
        offset += m->m_pkthdr.csum_data;        /* checksum offset */

        if (offset + sizeof(u_short) > m->m_len) {
                kprintf("delayed m_pullup, m->len: %d  off: %d  p: %d\n",
                    m->m_len, offset, ip->ip_p);
                /*
                 * XXX
                 * this shouldn't happen, but if it does, the
                 * correct behavior may be to insert the checksum
                 * in the existing chain instead of rearranging it.
                 */
                m = m_pullup(m, offset + sizeof(u_short));
        }
        *(u_short *)(m->m_data + offset) = csum;
}

/*
 * 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.
 *
 * XXX This routine assumes that the packet has no options in place.
 */
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 + (u_short)ntohs(ip->ip_len) > IP_MAXPACKET) {
                *phlen = 0;
                return (m);             /* XXX should fail */
        }
        if (p->ipopt_dst.s_addr)
                ip->ip_dst = p->ipopt_dst;
        if (m->m_flags & M_EXT || m->m_data - optlen < m->m_pktdat) {
                MGETHDR(n, M_NOWAIT, MT_HEADER);
                if (n == NULL) {
                        *phlen = 0;
                        return (m);
                }
                n->m_pkthdr.rcvif = NULL;
                n->m_pkthdr.len = m->m_pkthdr.len + optlen;
                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;
                memcpy(mtod(m, void *), ip, sizeof(struct ip));
        } else {
                m->m_data -= optlen;
                m->m_len += optlen;
                m->m_pkthdr.len += optlen;
                bcopy(ip, mtod(m, caddr_t), sizeof(struct ip));
        }
        ip = mtod(m, struct ip *);
        bcopy(p->ipopt_list, ip + 1, optlen);
        *phlen = sizeof(struct ip) + optlen;
        ip->ip_vhl = IP_MAKE_VHL(IPVERSION, *phlen >> 2);
        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_VHL_HL(ip->ip_vhl) << 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;
                }

                KASSERT(cnt >= IPOPT_OLEN + sizeof *cp,
                    ("ip_optcopy: malformed ipv4 option"));
                optlen = cp[IPOPT_OLEN];
                KASSERT(optlen >= IPOPT_OLEN + sizeof *cp && optlen <= cnt,
                    ("ip_optcopy: malformed ipv4 option"));

                /* bogus lengths should have been caught by ip_dooptions */
                if (optlen > cnt)
                        optlen = cnt;
                if (IPOPT_COPIED(opt)) {
                        bcopy(cp, dp, optlen);
                        dp += optlen;
                }
        }
        for (optlen = dp - (u_char *)(jp+1); optlen & 0x3; optlen++)
                *dp++ = IPOPT_EOL;
        return (optlen);
}

/*
 * IP socket option processing.
 */
void
ip_ctloutput(netmsg_t msg)
{
        struct socket *so = msg->base.nm_so;
        struct sockopt *sopt = msg->ctloutput.nm_sopt;
        struct  inpcb *inp = so->so_pcb;
        int     error, optval;

        error = optval = 0;

        /* Get socket's owner cpuid hint */
        if (sopt->sopt_level == SOL_SOCKET &&
            sopt->sopt_dir == SOPT_GET &&
            sopt->sopt_name == SO_CPUHINT) {
                optval = mycpuid;
                soopt_from_kbuf(sopt, &optval, sizeof(optval));
                goto done;
        }

        if (sopt->sopt_level != IPPROTO_IP) {
                error = EINVAL;
                goto done;
        }

        switch (sopt->sopt_name) {
        case IP_MULTICAST_IF:
        case IP_MULTICAST_VIF:
        case IP_MULTICAST_TTL:
        case IP_MULTICAST_LOOP:
        case IP_ADD_MEMBERSHIP:
        case IP_DROP_MEMBERSHIP:
                /*
                 * Handle multicast options in netisr0
                 */
                if (&curthread->td_msgport != netisr_cpuport(0)) {
                        /* NOTE: so_port MUST NOT be checked in netisr0 */
                        msg->lmsg.ms_flags |= MSGF_IGNSOPORT;
                        lwkt_forwardmsg(netisr_cpuport(0), &msg->lmsg);
                        return;
                }
                break;
        }

        switch (sopt->sopt_dir) {
        case SOPT_SET:
                switch (sopt->sopt_name) {
                case IP_OPTIONS:
#ifdef notyet
                case IP_RETOPTS:
#endif
                {
                        struct mbuf *m;
                        if (sopt->sopt_valsize > MLEN) {
                                error = EMSGSIZE;
                                break;
                        }
                        MGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_HEADER);
                        if (m == NULL) {
                                error = ENOBUFS;
                                break;
                        }
                        m->m_len = sopt->sopt_valsize;
                        error = soopt_to_kbuf(sopt, mtod(m, void *), m->m_len,
                                              m->m_len);
                        error = ip_pcbopts(sopt->sopt_name,
                                           &inp->inp_options, m);
                        goto done;
                }

                case IP_TOS:
                case IP_TTL:
                case IP_MINTTL:
                case IP_RECVOPTS:
                case IP_RECVRETOPTS:
                case IP_RECVDSTADDR:
                case IP_RECVIF:
                case IP_RECVTOS:
                case IP_RECVTTL:
                        error = soopt_to_kbuf(sopt, &optval, sizeof optval,
                                             sizeof optval);
                        if (error)
                                break;
                        switch (sopt->sopt_name) {
                        case IP_TOS:
                                inp->inp_ip_tos = optval;
                                break;

                        case IP_TTL:
                                inp->inp_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_RECVTOS:
                                OPTSET(INP_RECVTOS);
                                break;

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

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

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

                        switch (optval) {
                        case IP_PORTRANGE_DEFAULT:
                                inp->inp_flags &= ~(INP_LOWPORT);
                                inp->inp_flags &= ~(INP_HIGHPORT);
                                break;

                        case IP_PORTRANGE_HIGH:
                                inp->inp_flags &= ~(INP_LOWPORT);
                                inp->inp_flags |= INP_HIGHPORT;
                                break;

                        case IP_PORTRANGE_LOW:
                                inp->inp_flags &= ~(INP_HIGHPORT);
                                inp->inp_flags |= INP_LOWPORT;
                                break;

                        default:
                                error = EINVAL;
                                break;
                        }
                        break;


                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;

        case SOPT_GET:
                switch (sopt->sopt_name) {
                case IP_OPTIONS:
                case IP_RETOPTS:
                        if (inp->inp_options)
                                soopt_from_kbuf(sopt, mtod(inp->inp_options,
                                                           char *),
                                                inp->inp_options->m_len);
                        else
                                sopt->sopt_valsize = 0;
                        break;

                case IP_TOS:
                case IP_TTL:
                case IP_MINTTL:
                case IP_RECVOPTS:
                case IP_RECVRETOPTS:
                case IP_RECVDSTADDR:
                case IP_RECVTOS:
                case IP_RECVTTL:
                case IP_RECVIF:
                case IP_PORTRANGE:
                        switch (sopt->sopt_name) {

                        case IP_TOS:
                                optval = inp->inp_ip_tos;
                                break;

                        case IP_TTL:
                                optval = inp->inp_ip_ttl;
                                break;
                        case IP_MINTTL:
                                optval = inp->inp_ip_minttl;
                                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_RECVTOS:
                                optval = OPTBIT(INP_RECVTOS);
                                break;

                        case IP_RECVTTL:
                                optval = OPTBIT(INP_RECVTTL);
                                break;

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

                        case IP_PORTRANGE:
                                if (inp->inp_flags & INP_HIGHPORT)
                                        optval = IP_PORTRANGE_HIGH;
                                else if (inp->inp_flags & INP_LOWPORT)
                                        optval = IP_PORTRANGE_LOW;
                                else
                                        optval = 0;
                                break;
                        }
                        soopt_from_kbuf(sopt, &optval, sizeof optval);
                        break;

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

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                break;
        }
done:
        lwkt_replymsg(&msg->lmsg, 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.
 */
static int
ip_pcbopts(int optname, struct mbuf **pcbopt, struct mbuf *m)
{
        int cnt, optlen;
        u_char *cp;
        u_char opt;

        /* turn off any old options */
        if (*pcbopt)
                m_free(*pcbopt);
        *pcbopt = NULL;
        if (m == NULL || m->m_len == 0) {
                /*
                 * Only turning off any previous options.
                 */
                if (m != NULL)
                        m_free(m);
                return (0);
        }

        if (m->m_len % sizeof(int32_t))
                goto bad;
        /*
         * IP first-hop destination address will be stored before
         * actual options; move other options back
         * and clear it when none present.
         */
        if (m->m_data + m->m_len + sizeof(struct in_addr) >= &m->m_dat[MLEN])
                goto bad;
        cnt = m->m_len;
        m->m_len += sizeof(struct in_addr);
        cp = mtod(m, u_char *) + sizeof(struct in_addr);
        bcopy(mtod(m, caddr_t), cp, cnt);
        bzero(mtod(m, caddr_t), sizeof(struct in_addr));

        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)
                                goto bad;
                        optlen = cp[IPOPT_OLEN];
                        if (optlen < IPOPT_OLEN + sizeof *cp || optlen > cnt)
                                goto bad;
                }
                switch (opt) {

                default:
                        break;

                case IPOPT_LSRR:
                case 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 (optlen < IPOPT_MINOFF - 1 + sizeof(struct in_addr))
                                goto bad;
                        m->m_len -= sizeof(struct in_addr);
                        cnt -= sizeof(struct in_addr);
                        optlen -= sizeof(struct in_addr);
                        cp[IPOPT_OLEN] = optlen;
                        /*
                         * Move first hop before start of options.
                         */
                        bcopy(&cp[IPOPT_OFFSET+1], mtod(m, caddr_t),
                              sizeof(struct in_addr));
                        /*
                         * Then copy rest of options back
                         * to close up the deleted entry.
                         */
                        bcopy(&cp[IPOPT_OFFSET+1] + sizeof(struct in_addr),
                              &cp[IPOPT_OFFSET+1],
                              cnt - (IPOPT_MINOFF - 1));
                        break;
                }
        }
        if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
                goto bad;
        *pcbopt = m;
        return (0);

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

/*
 * XXX
 * The whole multicast option thing needs to be re-thought.
 * Several of these options are equally applicable to non-multicast
 * transmission, and one (IP_MULTICAST_TTL) totally duplicates a
 * standard option (IP_TTL).
 */

/*
 * 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;

        if (ifindexp)
                *ifindexp = 0;
        if (ntohl(a->s_addr) >> 24 == 0) {
                ifindex = ntohl(a->s_addr) & 0xffffff;
                if (ifindex < 0 || if_index < ifindex)
                        return NULL;
                ifp = ifindex2ifnet[ifindex];
                if (ifindexp)
                        *ifindexp = ifindex;
        } else {
                ifp = INADDR_TO_IFP(a);
        }
        return ifp;
}

/*
 * Set the IP multicast options in response to user setsockopt().
 */
static int
ip_setmoptions(struct sockopt *sopt, struct ip_moptions **imop)
{
        int error = 0;
        int i;
        struct ip_mreqn mreqn;
        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 = kmalloc(sizeof *imo, M_IPMOPTS, M_WAITOK);

                imo->imo_multicast_ifp = NULL;
                imo->imo_multicast_addr.s_addr = INADDR_ANY;
                imo->imo_multicast_vif = -1;
                imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
                imo->imo_multicast_loop = IP_DEFAULT_MULTICAST_LOOP;
                imo->imo_num_memberships = 0;
                /* Assign imo to imop after all fields are setup */
                cpu_sfence();
                *imop = imo;
        }
        switch (sopt->sopt_name) {
        /* store an index number for the vif you wanna use in the send */
        case IP_MULTICAST_VIF:
                if (legal_vif_num == 0) {
                        error = EOPNOTSUPP;
                        break;
                }
                error = soopt_to_kbuf(sopt, &i, sizeof i, sizeof i);
                if (error)
                        break;
                if (!legal_vif_num(i) && (i != -1)) {
                        error = EINVAL;
                        break;
                }
                imo->imo_multicast_vif = i;
                break;

        case IP_MULTICAST_IF:
                /*
                 * Select the interface for outgoing multicast packets.
                 */
                if (sopt->sopt_valsize >= sizeof(mreqn)) {
                        /*
                         * Linux compat.
                         */
                        error = soopt_to_kbuf(sopt, &mreqn,
                            sizeof(mreqn), sizeof(mreqn));
                        if (error)
                                break;
                } else if (sopt->sopt_valsize >= sizeof(struct ip_mreq)) {
                        /*
                         * Linux compat.
                         */
                        mreqn.imr_ifindex = 0;
                        error = soopt_to_kbuf(sopt, &mreqn,
                            sizeof(struct ip_mreq), sizeof(struct ip_mreq));
                        if (error)
                                break;
                } else {
                        mreqn.imr_ifindex = 0;
                        error = soopt_to_kbuf(sopt, &mreqn.imr_address,
                            sizeof(struct in_addr), sizeof(struct in_addr));
                        if (error)
                                break;
                }

                ifindex = mreqn.imr_ifindex;
                if (ifindex != 0) {
                        if (ifindex < 0 || if_index < ifindex) {
                                error = EINVAL;
                                break;
                        }
                        ifp = ifindex2ifnet[ifindex];
                        mreqn.imr_address.s_addr = htonl(ifindex & 0xffffff);
                } else {
                        /*
                         * 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 (mreqn.imr_address.s_addr == INADDR_ANY) {
                                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(&mreqn.imr_address, &ifindex);
                }

                if (ifp == NULL || !(ifp->if_flags & IFF_MULTICAST)) {
                        error = EADDRNOTAVAIL;
                        break;
                }
                imo->imo_multicast_ifp = ifp;
                if (ifindex)
                        imo->imo_multicast_addr = mreqn.imr_address;
                else
                        imo->imo_multicast_addr.s_addr = INADDR_ANY;
                break;

        case IP_MULTICAST_TTL:
                /*
                 * Set the IP time-to-live for outgoing multicast packets.
                 * The original multicast API required a char argument,
                 * which is inconsistent with the rest of the socket API.
                 * We allow either a char or an int.
                 */
                if (sopt->sopt_valsize == 1) {
                        u_char ttl;
                        error = soopt_to_kbuf(sopt, &ttl, 1, 1);
                        if (error)
                                break;
                        imo->imo_multicast_ttl = ttl;
                } else {
                        u_int ttl;
                        error = soopt_to_kbuf(sopt, &ttl, sizeof ttl, sizeof ttl);
                        if (error)
                                break;
                        if (ttl > 255)
                                error = EINVAL;
                        else
                                imo->imo_multicast_ttl = ttl;
                }
                break;

        case IP_MULTICAST_LOOP:
                /*
                 * Set the loopback flag for outgoing multicast packets.
                 * Must be zero or one.  The original multicast API required a
                 * char argument, which is inconsistent with the rest
                 * of the socket API.  We allow either a char or an int.
                 */
                if (sopt->sopt_valsize == 1) {
                        u_char loop;

                        error = soopt_to_kbuf(sopt, &loop, 1, 1);
                        if (error)
                                break;
                        imo->imo_multicast_loop = !!loop;
                } else {
                        u_int loop;

                        error = soopt_to_kbuf(sopt, &loop, sizeof loop,
                                            sizeof loop);
                        if (error)
                                break;
                        imo->imo_multicast_loop = !!loop;
                }
                break;

        case IP_ADD_MEMBERSHIP:
                /*
                 * Add a multicast group membership.
                 * Group must be a valid IP multicast address.
                 */
                if (sopt->sopt_valsize >= sizeof(mreqn)) {
                        error = soopt_to_kbuf(sopt, &mreqn,
                            sizeof(mreqn), sizeof(mreqn));
                        if (error)
                                break;
                } else {
                        mreqn.imr_ifindex = 0;
                        error = soopt_to_kbuf(sopt, &mreqn,
                            sizeof(struct ip_mreq), sizeof(struct ip_mreq));
                        if (error)
                                break;
                }

                if (!IN_MULTICAST(ntohl(mreqn.imr_multiaddr.s_addr))) {
                        error = EINVAL;
                        break;
                }

                ifindex = mreqn.imr_ifindex;
                if (ifindex != 0) {
                        if (ifindex < 0 || if_index < ifindex) {
                                error = EINVAL;
                                break;
                        }
                        ifp = ifindex2ifnet[ifindex];
                } else if (mreqn.imr_address.s_addr == INADDR_ANY) {
                        struct sockaddr_in dst;
                        struct rtentry *rt;

                        /*
                         * If no interface address or index was provided,
                         * use the interface of the route to the given
                         * multicast address.
                         */
                        bzero(&dst, sizeof(struct sockaddr_in));
                        dst.sin_len = sizeof(struct sockaddr_in);
                        dst.sin_family = AF_INET;
                        dst.sin_addr = mreqn.imr_multiaddr;
                        rt = rtlookup((struct sockaddr *)&dst);
                        if (rt == NULL) {
                                error = EADDRNOTAVAIL;
                                break;
                        }
                        --rt->rt_refcnt;
                        ifp = rt->rt_ifp;
                } else {
                        ifp = ip_multicast_if(&mreqn.imr_address, NULL);
                }

                /*
                 * See if we found an interface, and confirm that it
                 * supports multicast.
                 */
                if (ifp == NULL || !(ifp->if_flags & IFF_MULTICAST)) {
                        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 &&
                            imo->imo_membership[i]->inm_addr.s_addr
                                                == mreqn.imr_multiaddr.s_addr)
                                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(&mreqn.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.
                 */
                if (sopt->sopt_valsize >= sizeof(mreqn)) {
                        error = soopt_to_kbuf(sopt, &mreqn,
                            sizeof(mreqn), sizeof(mreqn));
                        if (error)
                                break;
                } else {
                        mreqn.imr_ifindex = 0;
                        error = soopt_to_kbuf(sopt, &mreqn,
                            sizeof(struct ip_mreq), sizeof(struct ip_mreq));
                        if (error)
                                break;
                }

                if (!IN_MULTICAST(ntohl(mreqn.imr_multiaddr.s_addr))) {
                        error = EINVAL;
                        break;
                }

                /*
                 * If an interface index or address was specified, get a
                 * pointer to its ifnet structure.
                 */
                ifindex = mreqn.imr_ifindex;
                if (ifindex != 0) {
                        if (ifindex < 0 || if_index < ifindex) {
                                error = EINVAL;
                                break;
                        }
                        ifp = ifindex2ifnet[ifindex];
                } else if (mreqn.imr_address.s_addr == INADDR_ANY) {
                        ifp = NULL;
                } else {
                        ifp = ip_multicast_if(&mreqn.imr_address, 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) &&
                            imo->imo_membership[i]->inm_addr.s_addr ==
                            mreqn.imr_multiaddr.s_addr)
                                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;
        }

        return (error);
}

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

        error = 0;
        switch (sopt->sopt_name) {
        case IP_MULTICAST_VIF:
                if (imo != NULL)
                        optval = imo->imo_multicast_vif;
                else
                        optval = -1;
                soopt_from_kbuf(sopt, &optval, sizeof optval);
                break;

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

        case IP_MULTICAST_TTL:
                if (imo == NULL)
                        optval = coptval = IP_DEFAULT_MULTICAST_TTL;
                else
                        optval = coptval = imo->imo_multicast_ttl;
                if (sopt->sopt_valsize == 1)
                        soopt_from_kbuf(sopt, &coptval, 1);
                else
                        soopt_from_kbuf(sopt, &optval, sizeof optval);
                break;

        case IP_MULTICAST_LOOP:
                if (imo == NULL)
                        optval = coptval = IP_DEFAULT_MULTICAST_LOOP;
                else
                        optval = coptval = imo->imo_multicast_loop;
                if (sopt->sopt_valsize == 1)
                        soopt_from_kbuf(sopt, &coptval, 1);
                else
                        soopt_from_kbuf(sopt, &optval, sizeof optval);
                break;

        default:
                error = ENOPROTOOPT;
                break;
        }
        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]);
                kfree(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 a loopback interface -- evil, but easier than
 * replicating that code here.
 */
static void
ip_mloopback(struct ifnet *ifp, struct mbuf *m, struct sockaddr_in *dst,
             int hlen)
{
        struct ip *ip;
        struct mbuf *copym;

        copym = m_copypacket(m, M_NOWAIT);
        if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
                copym = m_pullup(copym, hlen);
        if (copym != NULL) {
                /*
                 * if the checksum hasn't been computed, mark it as valid
                 */
                if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
                        in_delayed_cksum(copym);
                        copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
                        copym->m_pkthdr.csum_flags |=
                            CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
                        copym->m_pkthdr.csum_data = 0xffff;
                }
                /*
                 * 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 *);
                ip->ip_sum = 0;
                if (ip->ip_vhl == IP_VHL_BORING) {
                        ip->ip_sum = in_cksum_hdr(ip);
                } else {
                        ip->ip_sum = in_cksum(copym, hlen);
                }
                /*
                 * NB:
                 * It's not clear whether there are any lingering
                 * reentrancy problems in other areas which might
                 * be exposed by using ip_input directly (in
                 * particular, everything which modifies the packet
                 * in-place).  Yet another option is using the
                 * protosw directly to deliver the looped back
                 * packet.  For the moment, we'll err on the side
                 * of safety by using if_simloop().
                 */
#if 1 /* XXX */
                if (dst->sin_family != AF_INET) {
                        kprintf("ip_mloopback: bad address family %d\n",
                                                dst->sin_family);
                        dst->sin_family = AF_INET;
                }
#endif
                if_simloop(ifp, copym, dst->sin_family, 0);
        }
}