if_disc.c

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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
 *	$Id: if_disc.c,v 1.21 1998/12/14 01:59:16 eivind 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/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>

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

#include "bpfilter.h"
#include "opt_inet.h"

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

static void discattach __P((void *dummy));
PSEUDO_SET(discattach, if_disc);

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

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

	ifp->if_name = "ds";
	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;
	if_attach(ifp);
#if NBPFILTER > 0
	bpfattach(ifp, DLT_NULL, sizeof(u_int));
#endif
}

static int
discoutput(ifp, m, dst, rt)
	struct ifnet *ifp;
	register struct mbuf *m;
	struct sockaddr *dst;
	register struct rtentry *rt;
{
	if ((m->m_flags & M_PKTHDR) == 0)
		panic("discoutput no HDR");
#if NBPFILTER > 0
	/* 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) {
		/*
		 * We need to prepend the address family as
		 * a four byte field.  Cons up a dummy header
		 * to pacify bpf.  This is safe because bpf
		 * will only read from the mbuf (i.e., it won't
		 * try to free it or keep a pointer a to it).
		 */
		struct mbuf m0;
		u_int af = dst->sa_family;

		m0.m_next = m;
		m0.m_len = 4;
		m0.m_data = (char *)&af;

		bpf_mtap(&discif, &m0);
	}
#endif
	m->m_pkthdr.rcvif = ifp;

	ifp->if_opackets++;
	ifp->if_obytes += m->m_pkthdr.len;

	m_freem(m);
	return 0;
}

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

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

	switch (cmd) {

	case SIOCSIFADDR:
		ifp->if_flags |= IFF_UP;
		ifa = (struct ifaddr *)data;
		if (ifa != 0)
			ifa->ifa_rtrequest = discrtrequest;
		/*
		 * 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

		default:
			error = EAFNOSUPPORT;
			break;
		}
		break;

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

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