/*      $FreeBSD: src/sys/netinet6/in6_gif.c,v 1.2.2.7 2003/01/23 21:06:47 sam Exp $    */
/*      $KAME: in6_gif.c,v 1.49 2001/05/14 14:02:17 itojun 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.
 */

#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/queue.h>
#include <sys/syslog.h>
#include <sys/protosw.h>

#include <sys/malloc.h>

#include <net/if_var.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#ifdef INET
#include <netinet/ip.h>
#endif
#include <netinet/ip_encap.h>
#ifdef INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_gif.h>
#include <netinet6/in6_var.h>
#endif
#include <netinet6/ip6protosw.h>
#include <netinet/ip_ecn.h>
#ifdef INET6
#include <netinet6/ip6_ecn.h>
#endif

#include <net/gif/if_gif.h>

#include <net/net_osdep.h>

#ifdef INET6
static int gif_validate6(const struct ip6_hdr *, struct gif_softc *,
                         struct ifnet *);

extern  struct domain inet6domain;
struct protosw in6_gif_protosw =
    {
        .pr_type = SOCK_RAW,
        .pr_domain = &inet6domain,
        .pr_protocol = 0 /* IPPROTO_IPV[46] */,
        .pr_flags = PR_ATOMIC|PR_ADDR,

        .pr_input = in6_gif_input,
        .pr_output = rip6_output,
        .pr_ctlinput = NULL,
        .pr_ctloutput = rip6_ctloutput,

        .pr_usrreqs = &rip6_usrreqs
    };

/*
 * family = family of the packet to be encapsulate.
 */
int
in6_gif_output(struct ifnet *ifp, int family, struct mbuf *m)
{
        struct gif_softc *sc = (struct gif_softc*)ifp;
        struct route_in6 *ro = &sc->gif_ro6[mycpu->gd_cpuid];
        struct sockaddr_in6 *dst = (struct sockaddr_in6 *)&ro->ro_dst;
        struct sockaddr_in6 *sin6_src = (struct sockaddr_in6 *)sc->gif_psrc;
        struct sockaddr_in6 *sin6_dst = (struct sockaddr_in6 *)sc->gif_pdst;
        struct ip6_hdr *ip6;
        int proto;
        u_int8_t itos, otos;

        if (sin6_src == NULL || sin6_dst == NULL ||
            sin6_src->sin6_family != AF_INET6 ||
            sin6_dst->sin6_family != AF_INET6) {
                m_freem(m);
                return EAFNOSUPPORT;
        }

        switch (family) {
#ifdef INET
        case AF_INET:
            {
                struct ip *ip;

                proto = IPPROTO_IPV4;
                if (m->m_len < sizeof(*ip)) {
                        m = m_pullup(m, sizeof(*ip));
                        if (!m)
                                return ENOBUFS;
                }
                ip = mtod(m, struct ip *);
                itos = ip->ip_tos;
                break;
            }
#endif
#ifdef INET6
        case AF_INET6:
            {
                struct ip6_hdr *ip6;
                proto = IPPROTO_IPV6;
                if (m->m_len < sizeof(*ip6)) {
                        m = m_pullup(m, sizeof(*ip6));
                        if (!m)
                                return ENOBUFS;
                }
                ip6 = mtod(m, struct ip6_hdr *);
                itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
                break;
            }
#endif
        default:
#ifdef DEBUG
                kprintf("in6_gif_output: warning: unknown family %d passed\n",
                        family);
#endif
                m_freem(m);
                return EAFNOSUPPORT;
        }

        /* prepend new IP header */
        M_PREPEND(m, sizeof(struct ip6_hdr), M_NOWAIT);
        if (m && m->m_len < sizeof(struct ip6_hdr))
                m = m_pullup(m, sizeof(struct ip6_hdr));
        if (m == NULL) {
                kprintf("ENOBUFS in in6_gif_output %d\n", __LINE__);
                return ENOBUFS;
        }

        ip6 = mtod(m, struct ip6_hdr *);
        ip6->ip6_flow   = 0;
        ip6->ip6_vfc    &= ~IPV6_VERSION_MASK;
        ip6->ip6_vfc    |= IPV6_VERSION;
        ip6->ip6_plen   = htons((u_short)m->m_pkthdr.len);
        ip6->ip6_nxt    = proto;
        ip6->ip6_hlim   = ip6_gif_hlim;
        ip6->ip6_src    = sin6_src->sin6_addr;
        /* bidirectional configured tunnel mode */
        if (!IN6_IS_ADDR_UNSPECIFIED(&sin6_dst->sin6_addr))
                ip6->ip6_dst = sin6_dst->sin6_addr;
        else  {
                m_freem(m);
                return ENETUNREACH;
        }
        if (ifp->if_flags & IFF_LINK1)
                ip_ecn_ingress(ECN_ALLOWED, &otos, &itos);
        else
                ip_ecn_ingress(ECN_NOCARE, &otos, &itos);
        ip6->ip6_flow &= ~ntohl(0xff00000);
        ip6->ip6_flow |= htonl((u_int32_t)otos << 20);

        if (dst->sin6_family != sin6_dst->sin6_family ||
             !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &sin6_dst->sin6_addr)) {
                /* cache route doesn't match */
                bzero(dst, sizeof(*dst));
                dst->sin6_family = sin6_dst->sin6_family;
                dst->sin6_len = sizeof(struct sockaddr_in6);
                dst->sin6_addr = sin6_dst->sin6_addr;
                if (ro->ro_rt != NULL) {
                        RTFREE(ro->ro_rt);
                        ro->ro_rt = NULL;
                }
#if 0
                sc->gif_if.if_mtu = GIF_MTU;
#endif
        }

        if (ro->ro_rt == NULL) {
                rtalloc((struct route *)ro);
                if (ro->ro_rt == NULL) {
                        m_freem(m);
                        return ENETUNREACH;
                }

                /* if it constitutes infinite encapsulation, punt. */
                if (ro->ro_rt->rt_ifp == ifp) {
                        m_freem(m);
                        return ENETUNREACH;     /*XXX*/
                }
#if 0
                ifp->if_mtu = ro->ro_rt->rt_ifp->if_mtu -
                              sizeof(struct ip6_hdr);
#endif
        }

#ifdef IPV6_MINMTU
        /*
         * force fragmentation to minimum MTU, to avoid path MTU discovery.
         * it is too painful to ask for resend of inner packet, to achieve
         * path MTU discovery for encapsulated packets.
         */
        return (ip6_output(m, 0, ro, IPV6_MINMTU, 0, NULL, NULL));
#else
        return (ip6_output(m, 0, ro, 0, 0, NULL, NULL));
#endif
}

int
in6_gif_input(struct mbuf **mp, int *offp, int proto)
{
        struct mbuf *m = *mp;
        struct ifnet *gifp = NULL;
        struct ip6_hdr *ip6;
        int af = 0;
        u_int32_t otos;

        ip6 = mtod(m, struct ip6_hdr *);

        gifp = (struct ifnet *)encap_getarg(m);

        if (gifp == NULL || !(gifp->if_flags & IFF_UP)) {
                m_freem(m);
                ip6stat.ip6s_nogif++;
                return IPPROTO_DONE;
        }

        otos = ip6->ip6_flow;
        m_adj(m, *offp);

        switch (proto) {
#ifdef INET
        case IPPROTO_IPV4:
            {
                struct ip *ip;
                u_int8_t otos8;
                af = AF_INET;
                otos8 = (ntohl(otos) >> 20) & 0xff;
                if (m->m_len < sizeof(*ip)) {
                        m = m_pullup(m, sizeof(*ip));
                        if (!m)
                                return IPPROTO_DONE;
                }
                ip = mtod(m, struct ip *);
                if (gifp->if_flags & IFF_LINK1)
                        ip_ecn_egress(ECN_ALLOWED, &otos8, &ip->ip_tos);
                else
                        ip_ecn_egress(ECN_NOCARE, &otos8, &ip->ip_tos);
                break;
            }
#endif /* INET */
#ifdef INET6
        case IPPROTO_IPV6:
            {
                struct ip6_hdr *ip6;
                af = AF_INET6;
                if (m->m_len < sizeof(*ip6)) {
                        m = m_pullup(m, sizeof(*ip6));
                        if (!m)
                                return IPPROTO_DONE;
                }
                ip6 = mtod(m, struct ip6_hdr *);
                if (gifp->if_flags & IFF_LINK1)
                        ip6_ecn_egress(ECN_ALLOWED, &otos, &ip6->ip6_flow);
                else
                        ip6_ecn_egress(ECN_NOCARE, &otos, &ip6->ip6_flow);
                break;
            }
#endif
        default:
                ip6stat.ip6s_nogif++;
                m_freem(m);
                return IPPROTO_DONE;
        }

        gif_input(m, af, gifp);
        return IPPROTO_DONE;
}

/*
 * validate outer address.
 */
static int
gif_validate6(const struct ip6_hdr *ip6, struct gif_softc *sc,
              struct ifnet *ifp)
{
        struct sockaddr_in6 *src, *dst;

        src = (struct sockaddr_in6 *)sc->gif_psrc;
        dst = (struct sockaddr_in6 *)sc->gif_pdst;

        /*
         * Check for address match.  Note that the check is for an incoming
         * packet.  We should compare the *source* address in our configuration
         * and the *destination* address of the packet, and vice versa.
         */
        if (!IN6_ARE_ADDR_EQUAL(&src->sin6_addr, &ip6->ip6_dst) ||
            !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_src))
                return 0;

        /* martian filters on outer source - done in ip6_input */

        /* ingress filters on outer source */
        if (!(sc->gif_if.if_flags & IFF_LINK2) && ifp) {
                struct sockaddr_in6 sin6;
                struct rtentry *rt;

                bzero(&sin6, sizeof(sin6));
                sin6.sin6_family = AF_INET6;
                sin6.sin6_len = sizeof(struct sockaddr_in6);
                sin6.sin6_addr = ip6->ip6_src;
                sin6.sin6_scope_id = 0; /* XXX */

                rt = rtpurelookup((struct sockaddr *)&sin6);
                if (rt != NULL)
                        --rt->rt_refcnt;
                if (rt == NULL || rt->rt_ifp != ifp) {
#if 0
                        log(LOG_WARNING, "%s: packet from %s dropped "
                            "due to ingress filter\n", if_name(&sc->gif_if),
                            ip6_sprintf(&sin6.sin6_addr));
#endif
                        return 0;
                }
        }

        return 128 * 2;
}

/*
 * we know that we are in IFF_UP, outer address available, and outer family
 * matched the physical addr family.  see gif_encapcheck().
 * sanity check for arg should have been done in the caller.
 */
int
gif_encapcheck6(const struct mbuf *m, int off, int proto, void *arg)
{
        struct ip6_hdr ip6;
        struct gif_softc *sc;
        struct ifnet *ifp;

        /* sanity check done in caller */
        sc = (struct gif_softc *)arg;

        m_copydata(m, 0, sizeof(ip6), &ip6);
        ifp = (m->m_flags & M_PKTHDR) ? m->m_pkthdr.rcvif : NULL;

        return gif_validate6(&ip6, sc, ifp);
}

int
in6_gif_attach(struct gif_softc *sc)
{
        sc->encap_cookie6 = encap_attach_func(AF_INET6, -1, gif_encapcheck,
            &in6_gif_protosw, sc);
        if (sc->encap_cookie6 == NULL)
                return EEXIST;
        return 0;
}

int
in6_gif_detach(struct gif_softc *sc)
{
        int error;

        error = encap_detach(sc->encap_cookie6);
        if (error == 0)
                sc->encap_cookie6 = NULL;
        return error;
}

#endif /* INET6 */