/*      $NetBSD: if_faith.c,v 1.64 2024/09/07 06:17:37 andvar Exp $     */
/*      $KAME: if_faith.c,v 1.21 2001/02/20 07:59:26 itojun Exp $       */

/*
 * Copyright (c) 1982, 1986, 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.
 */
/*
 * derived from
 *      @(#)if_loop.c   8.1 (Berkeley) 6/10/93
 * Id: if_loop.c,v 1.22 1996/06/19 16:24:10 wollman Exp
 */

/*
 * IPv6-to-IPv4 TCP relay capturing interface
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_faith.c,v 1.64 2024/09/07 06:17:37 andvar Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <sys/device.h>
#include <sys/module.h>
#include <sys/atomic.h>

#include <sys/cpu.h>

#include <net/if.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/bpf.h>
#include <net/if_faith.h>

#ifdef  INET
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#endif

#ifdef INET6
#ifndef INET
#include <netinet/in.h>
#endif
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#endif

#include "ioconf.h"

static int      faithioctl(struct ifnet *, u_long, void *);
static int      faithoutput(struct ifnet *, struct mbuf *,
                            const struct sockaddr *, const struct rtentry *);
static void     faithrtrequest(int, struct rtentry *,
                               const struct rt_addrinfo *);

static int      faith_clone_create(struct if_clone *, int);
static int      faith_clone_destroy(struct ifnet *);

static struct if_clone faith_cloner =
    IF_CLONE_INITIALIZER("faith", faith_clone_create, faith_clone_destroy);

#define FAITHMTU        1500

static u_int faith_count;

/* ARGSUSED */
void
faithattach(int count)
{

        /*
         * Nothing to do here, initialization is handled by the
         * module initialization code in faithinit() below).
         */
}

static void
faithinit(void)
{
        if_clone_attach(&faith_cloner);
}

static int
faithdetach(void)
{
        int error = 0;

        if (faith_count != 0)
                error = EBUSY;

        if (error == 0)
                if_clone_detach(&faith_cloner);

        return error;
}

static int
faith_clone_create(struct if_clone *ifc, int unit)
{
        struct ifnet *ifp;

        ifp = if_alloc(IFT_FAITH);

        if_initname(ifp, ifc->ifc_name, unit);

        ifp->if_mtu = FAITHMTU;
        /* Change to BROADCAST experimentally to announce its prefix. */
        ifp->if_flags = /* IFF_LOOPBACK */ IFF_BROADCAST | IFF_MULTICAST;
        ifp->if_ioctl = faithioctl;
        ifp->if_output = faithoutput;
        ifp->if_type = IFT_FAITH;
        ifp->if_hdrlen = 0;
        ifp->if_addrlen = 0;
        ifp->if_dlt = DLT_NULL;
        if_attach(ifp);
        if_alloc_sadl(ifp);
        bpf_attach(ifp, DLT_NULL, sizeof(u_int));
        atomic_inc_uint(&faith_count);
        return (0);
}

int
faith_clone_destroy(struct ifnet *ifp)
{

        bpf_detach(ifp);
        if_detach(ifp);
        if_free(ifp);

        atomic_dec_uint(&faith_count);
        return (0);
}

static int
faithoutput(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
    const struct rtentry *rt)
{
        pktqueue_t *pktq;
        size_t pktlen;
        int s, error;
        uint32_t af;

        if ((m->m_flags & M_PKTHDR) == 0)
                panic("faithoutput no HDR");
        af = dst->sa_family;
        /* BPF write needs to be handled specially */
        if (af == AF_UNSPEC) {
                af = *(mtod(m, int *));
                m_adj(m, sizeof(int));
        }

        bpf_mtap_af(ifp, af, m, BPF_D_OUT);

        if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
                m_freem(m);
                return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
                        rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
        }
        pktlen = m->m_pkthdr.len;
        if_statadd2(ifp, if_opackets, 1, if_obytes, pktlen);
        switch (af) {
#ifdef INET
        case AF_INET:
                pktq = ip_pktq;
                break;
#endif
#ifdef INET6
        case AF_INET6:
                pktq = ip6_pktq;
                break;
#endif
        default:
                m_freem(m);
                return EAFNOSUPPORT;
        }

        /* XXX do we need more sanity checks? */
        KASSERT(pktq != NULL);
        m_set_rcvif(m, ifp);

        s = splnet();
        if (__predict_true(pktq_enqueue(pktq, m, 0))) {
                if_statadd2(ifp, if_ipackets, 1, if_ibytes, pktlen);
                error = 0;
        } else {
                m_freem(m);
                error = ENOBUFS;
        }
        splx(s);

        return error;
}

/* ARGSUSED */
static void
faithrtrequest(int cmd, struct rtentry *rt,
    const struct rt_addrinfo *info)
{
        if (rt)
                rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; /* for ISO */
}

/*
 * Process an ioctl request.
 */
/* ARGSUSED */
static int
faithioctl(struct ifnet *ifp, u_long cmd, void *data)
{
        struct ifaddr *ifa;
        struct ifreq *ifr = (struct ifreq *)data;
        int error = 0;

        switch (cmd) {

        case SIOCINITIFADDR:
                ifa = (struct ifaddr *)data;
                ifa->ifa_rtrequest = faithrtrequest;
                ifp->if_flags |= IFF_UP | IFF_RUNNING;
                /*
                 * Everything else is done at a higher level.
                 */
                break;

        case SIOCADDMULTI:
        case SIOCDELMULTI:
                if (ifr == 0) {
                        error = EAFNOSUPPORT;           /* XXX */
                        break;
                }
                switch (ifr->ifr_addr.sa_family) {
#ifdef INET
                case AF_INET:
                        break;
#endif
#ifdef INET6
                case AF_INET6:
                        break;
#endif

                default:
                        error = EAFNOSUPPORT;
                        break;
                }
                break;

        default:
                if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
                        error = 0;
                break;
        }
        return (error);
}

#ifdef INET6
/*
 * XXX could be slow
 * XXX could be layer violation to call sys/net from sys/netinet6
 */
int
faithprefix(struct in6_addr *in6)
{
        struct rtentry *rt;
        struct sockaddr_in6 sin6;
        int ret;

        if (ip6_keepfaith == 0)
                return 0;

        memset(&sin6, 0, sizeof(sin6));
        sin6.sin6_family = AF_INET6;
        sin6.sin6_len = sizeof(struct sockaddr_in6);
        sin6.sin6_addr = *in6;
        rt = rtalloc1((struct sockaddr *)&sin6, 0);
        if (rt && rt->rt_ifp && rt->rt_ifp->if_type == IFT_FAITH &&
            (rt->rt_ifp->if_flags & IFF_UP) != 0)
                ret = 1;
        else
                ret = 0;
        if (rt)
                rt_unref(rt);
        return ret;
}
#endif

/*
 * Module infrastructure
 */
#include "if_module.h"

IF_MODULE(MODULE_CLASS_DRIVER, faith, NULL)