/*
 * 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.
 *
 *      From: @(#)if_loop.c     8.1 (Berkeley) 6/10/93
 * $FreeBSD: src/sys/net/if_disc.c,v 1.26.2.2 2001/12/20 10:30:16 ru Exp $
 */

/*
 * Discard interface driver for protocol testing and timing.
 * (Based on the loopback.)
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>

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

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

#ifdef TINY_DSMTU
#define DSMTU   (1024+512)
#else
#define DSMTU   65532
#endif

static void discattach (void);

static struct   ifnet discif;
static int discoutput(struct ifnet *, struct mbuf *, struct sockaddr *,
                    struct rtentry *);
static void discrtrequest(int cmd, struct rtentry *rt);
static int discioctl(struct ifnet *, u_long, caddr_t, struct ucred *);

/* ARGSUSED */
static void
discattach(void)
{
        struct ifnet *ifp = &discif;

        if_initname(ifp, "ds", IF_DUNIT_NONE);
        ifp->if_mtu = DSMTU;
        ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
        ifp->if_ioctl = discioctl;
        ifp->if_output = discoutput;
        ifp->if_type = IFT_LOOP;
        ifp->if_hdrlen = 0;
        ifp->if_addrlen = 0;
        ifq_set_maxlen(&ifp->if_snd, 20);
        if_attach(ifp, NULL);
        bpfattach(ifp, DLT_NULL, sizeof(uint32_t));
}

static int
disc_modevent(module_t mod, int type, void *data)
{
        switch (type) {
        case MOD_LOAD:
                discattach();
                break;
        case MOD_UNLOAD:
                kprintf("if_disc module unload - not possible for this module type\n");
                return EINVAL;
        }
        return 0;
}

static moduledata_t disc_mod = {
        "if_disc",
        disc_modevent,
        NULL
};

DECLARE_MODULE(if_disc, disc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);

static int
discoutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
           struct rtentry *rt)
{
        if ((m->m_flags & M_PKTHDR) == 0)
                panic("discoutput no HDR");
        /* BPF write needs to be handled specially */
        if (dst->sa_family == AF_UNSPEC) {
                dst->sa_family = *(mtod(m, int *));
                m->m_len -= sizeof(int);
                m->m_pkthdr.len -= sizeof(int);
                m->m_data += sizeof(int);
        }

        if (discif.if_bpf) {
                bpf_gettoken();
                if (discif.if_bpf) {
                        /*
                         * We need to prepend the address family as
                         * a four byte field.
                         */
                        uint32_t af = dst->sa_family;

                        bpf_ptap(discif.if_bpf, m, &af, sizeof(af));
                }
                bpf_reltoken();
        }
        m->m_pkthdr.rcvif = ifp;

        IFNET_STAT_INC(ifp, opackets, 1);
        IFNET_STAT_INC(ifp, obytes, m->m_pkthdr.len);

        m_freem(m);
        return 0;
}

/* ARGSUSED */
static void
discrtrequest(int cmd, struct rtentry *rt)
{
        if (rt)
                rt->rt_rmx.rmx_mtu = DSMTU;
}

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

        switch (cmd) {

        case SIOCSIFADDR:
                ifp->if_flags |= IFF_UP;
                ifa = (struct ifaddr *)data;
                if (ifa != NULL)
                        ifa->ifa_rtrequest = discrtrequest;
                /*
                 * Everything else is done at a higher level.
                 */
                break;

        case SIOCADDMULTI:
        case SIOCDELMULTI:
                if (ifr == NULL) {
                        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;

        case SIOCSIFMTU:
                ifp->if_mtu = ifr->ifr_mtu;
                break;

        default:
                error = EINVAL;
        }
        return (error);
}