xnu-517.3.15.tar.gz

[apple/xnu.git] / bsd / net / bpf.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1990, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from the Stanford/CMU enet packet filter,
 * (net/enet.c) distributed as part of 4.3BSD, and code contributed
 * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
 * Berkeley Laboratory.
 *
 * 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.
 *
 *      @(#)bpf.c       8.2 (Berkeley) 3/28/94
 *
 * $FreeBSD: src/sys/net/bpf.c,v 1.59.2.5 2001/01/05 04:49:09 jdp Exp $
 */

#include "bpf.h"

#ifndef __GNUC__
#define inline
#else
#define inline __inline
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/time.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
#include <sys/filio.h>
#include <sys/sockio.h>
#include <sys/ttycom.h>
#include <sys/filedesc.h>

#if defined(sparc) && BSD < 199103
#include <sys/stream.h>
#endif
#include <sys/poll.h>

#include <sys/socket.h>
#include <sys/vnode.h>

#include <net/if.h>
#include <net/bpf.h>
#include <net/bpfdesc.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <net/firewire.h>

#include <machine/ansi.h>
#include <miscfs/devfs/devfs.h>
#include <net/dlil.h>

#if NBPFILTER > 0

/*
 * Older BSDs don't have kernel malloc.
 */
#if BSD < 199103
extern bcopy();
static caddr_t bpf_alloc();
#include <net/bpf_compat.h>
#define BPF_BUFSIZE (MCLBYTES-8)
#define UIOMOVE(cp, len, code, uio) uiomove(cp, len, code, uio)
#else
#define BPF_BUFSIZE 4096
#define UIOMOVE(cp, len, code, uio) uiomove(cp, len, uio)
#endif


#define PRINET  26                      /* interruptible */

/*
 * The default read buffer size is patchable.
 */
static int bpf_bufsize = BPF_BUFSIZE;
SYSCTL_INT(_debug, OID_AUTO, bpf_bufsize, CTLFLAG_RW, 
        &bpf_bufsize, 0, "");
static int bpf_maxbufsize = BPF_MAXBUFSIZE;
SYSCTL_INT(_debug, OID_AUTO, bpf_maxbufsize, CTLFLAG_RW, 
        &bpf_maxbufsize, 0, "");

/*
 *  bpf_iflist is the list of interfaces; each corresponds to an ifnet
 *  bpf_dtab holds pointer to the descriptors, indexed by minor device #
 */
static struct bpf_if    *bpf_iflist;
#ifdef __APPLE__
/*
 * BSD now stores the bpf_d in the dev_t which is a struct
 * on their system. Our dev_t is an int, so we still store
 * the bpf_d in a separate table indexed by minor device #.
 */
static struct bpf_d     **bpf_dtab = NULL;
static int                      bpf_dtab_size = 0;
static int                      nbpfilter = 0;

/*
 * Mark a descriptor free by making it point to itself.
 * This is probably cheaper than marking with a constant since
 * the address should be in a register anyway.
 */
#define D_ISFREE(d) ((d) == (d)->bd_next)
#define D_MARKFREE(d) ((d)->bd_next = (d))
#define D_MARKUSED(d) ((d)->bd_next = 0)
#endif /* __APPLE__ */

static int      bpf_allocbufs __P((struct bpf_d *));
static void     bpf_attachd __P((struct bpf_d *d, struct bpf_if *bp));
static void     bpf_detachd __P((struct bpf_d *d));
static void     bpf_freed __P((struct bpf_d *));
static void     bpf_mcopy __P((const void *, void *, size_t));
static int      bpf_movein __P((struct uio *, int,
                    struct mbuf **, struct sockaddr *, int *));
static int      bpf_setif __P((struct bpf_d *, struct ifreq *));
static inline void
                bpf_wakeup __P((struct bpf_d *));
static void     catchpacket __P((struct bpf_d *, u_char *, u_int,
                    u_int, void (*)(const void *, void *, size_t)));
static void     reset_d __P((struct bpf_d *));
static int       bpf_setf __P((struct bpf_d *, struct bpf_program *));

/*static  void *bpf_devfs_token[MAXBPFILTER];*/

static  int bpf_devsw_installed;

void bpf_init __P((void *unused));


/*
 * Darwin differs from BSD here, the following are static
 * on BSD and not static on Darwin.
 */
        d_open_t        bpfopen;
        d_close_t       bpfclose;
        d_read_t        bpfread;
        d_write_t       bpfwrite;
        d_ioctl_t       bpfioctl;
        select_fcn_t    bpfpoll;

#ifdef __APPLE__
void bpf_mtap(struct ifnet *, struct mbuf *);

int     bpfopen(), bpfclose(), bpfread(), bpfwrite(), bpfioctl(),
                bpfpoll();
#endif

/* Darwin's cdevsw struct differs slightly from BSDs */
#define CDEV_MAJOR 23
static struct cdevsw bpf_cdevsw = {
        /* open */      bpfopen,
        /* close */     bpfclose,
        /* read */      bpfread,
        /* write */     bpfwrite,
        /* ioctl */     bpfioctl,
        /* stop */      nulldev,
        /* reset */     nulldev,
        /* tty */       NULL,
        /* select */    bpfpoll,
        /* mmap */      eno_mmap,
        /* strategy*/   eno_strat,
        /* getc */      eno_getc,
        /* putc */      eno_putc,
        /* type */      0
};

#define SOCKADDR_HDR_LEN           offsetof(struct sockaddr, sa_data)

static int
bpf_movein(uio, linktype, mp, sockp, datlen)
        register struct uio *uio;
        int linktype, *datlen;
        register struct mbuf **mp;
        register struct sockaddr *sockp;
{
        struct mbuf *m;
        int error;
        int len;
        int hlen;

        /*
         * Build a sockaddr based on the data link layer type.
         * We do this at this level because the ethernet header
         * is copied directly into the data field of the sockaddr.
         * In the case of SLIP, there is no header and the packet
         * is forwarded as is.
         * Also, we are careful to leave room at the front of the mbuf
         * for the link level header.
         */
        switch (linktype) {

        case DLT_SLIP:
                sockp->sa_family = AF_INET;
                hlen = 0;
                break;

        case DLT_EN10MB:
                sockp->sa_family = AF_UNSPEC;
                /* XXX Would MAXLINKHDR be better? */
                hlen = sizeof(struct ether_header);
                break;

        case DLT_FDDI:
#if defined(__FreeBSD__) || defined(__bsdi__)
                sockp->sa_family = AF_IMPLINK;
                hlen = 0;
#else
                sockp->sa_family = AF_UNSPEC;
                /* XXX 4(FORMAC)+6(dst)+6(src)+3(LLC)+5(SNAP) */
                hlen = 24;
#endif
                break;

        case DLT_RAW:
        case DLT_NULL:
                sockp->sa_family = AF_UNSPEC;
                hlen = 0;
                break;

#ifdef __FreeBSD__
        case DLT_ATM_RFC1483:
                /*
                 * en atm driver requires 4-byte atm pseudo header.
                 * though it isn't standard, vpi:vci needs to be
                 * specified anyway.
                 */
                sockp->sa_family = AF_UNSPEC;
                hlen = 12;      /* XXX 4(ATM_PH) + 3(LLC) + 5(SNAP) */
                break;
#endif
        case DLT_PPP:
                sockp->sa_family = AF_UNSPEC;
                hlen = 4;       /* This should match PPP_HDRLEN */
                break;

        case DLT_APPLE_IP_OVER_IEEE1394:
                sockp->sa_family = AF_UNSPEC;
                hlen = sizeof(struct firewire_header);
                break;

        default:
                return (EIO);
        }
        if ((hlen + SOCKADDR_HDR_LEN) > sockp->sa_len) {
                return (EIO);
        }
        len = uio->uio_resid;
        *datlen = len - hlen;
        if ((unsigned)len > MCLBYTES)
                return (EIO);

        MGETHDR(m, M_WAIT, MT_DATA);
        if (m == 0)
                return (ENOBUFS);
        if (len > MHLEN) {
#if BSD >= 199103
                MCLGET(m, M_WAIT);
                if ((m->m_flags & M_EXT) == 0) {
#else
                MCLGET(m);
                if (m->m_len != MCLBYTES) {
#endif
                        error = ENOBUFS;
                        goto bad;
                }
        }
        m->m_pkthdr.len = m->m_len = len;
        m->m_pkthdr.rcvif = NULL;
        *mp = m;
        /*
         * Make room for link header.
         */
        if (hlen != 0) {
                m->m_pkthdr.len -= hlen;
                m->m_len -= hlen;
#if BSD >= 199103
                m->m_data += hlen; /* XXX */
#else
                m->m_off += hlen;
#endif
                error = UIOMOVE((caddr_t)sockp->sa_data, hlen, UIO_WRITE, uio);
                if (error)
                        goto bad;
        }
        error = UIOMOVE(mtod(m, caddr_t), len - hlen, UIO_WRITE, uio);
        if (!error)
                return (0);
 bad:
        m_freem(m);
        return (error);
}

#ifdef __APPLE__
/* Callback registered with Ethernet driver. */
int bpf_tap_callback(struct ifnet *ifp, struct mbuf *m)
{
    boolean_t funnel_state;

    funnel_state = thread_funnel_set(network_flock, TRUE);
     
    /*
     * Do nothing if the BPF tap has been turned off.
     * This is to protect from a potential race where this
     * call blocks on the funnel lock. And in the meantime
     * BPF is turned off, which will clear if_bpf.
     */
    if (ifp->if_bpf)
        bpf_mtap(ifp, m);

    thread_funnel_set(network_flock, funnel_state);
    return 0;
}

/*
 * Returns 1 on sucess, 0 on failure
 */
static int
bpf_dtab_grow(int increment)
{
        struct bpf_d **new_dtab = NULL;
        
        new_dtab = (struct bpf_d **)_MALLOC(sizeof(struct bpf_d *) * (bpf_dtab_size + increment), M_DEVBUF, M_WAIT);
        if  (new_dtab == NULL)
                return 0;

        if (bpf_dtab) {
                struct bpf_d **old_dtab;

                bcopy(bpf_dtab, new_dtab, sizeof(struct bpf_d *) * bpf_dtab_size);
                /*
                 * replace must be atomic with respect to free do bpf_dtab
                 * is always valid.
                 */
                old_dtab = bpf_dtab;
        bpf_dtab = new_dtab;
                _FREE(old_dtab, M_DEVBUF);
        } 
        else    bpf_dtab = new_dtab;
        
        bzero(bpf_dtab + bpf_dtab_size, sizeof(struct bpf_d *) * increment);
        
        bpf_dtab_size += increment;
        
        return 1;
}

static struct bpf_d *
bpf_make_dev_t(int maj)
{
        struct bpf_d *d;
        
        if (nbpfilter >= bpf_dtab_size && bpf_dtab_grow(NBPFILTER) == 0)
                return NULL;

        d = (struct bpf_d *)_MALLOC(sizeof(struct bpf_d), M_DEVBUF, M_WAIT);
        if (d != NULL) {
                int i = nbpfilter++;

                bzero(d, sizeof(struct bpf_d));
                bpf_dtab[i] = d;
                D_MARKFREE(bpf_dtab[i]);
                /*bpf_devfs_token[i]  = */devfs_make_node(makedev(maj, i),
                                                        DEVFS_CHAR, UID_ROOT, GID_WHEEL, 0600,
                                                        "bpf%d", i);
        }
        return d;
}

#endif

/*
 * Attach file to the bpf interface, i.e. make d listen on bp.
 * Must be called at splimp.
 */
static void
bpf_attachd(d, bp)
        struct bpf_d *d;
        struct bpf_if *bp;
{
        /*
         * Point d at bp, and add d to the interface's list of listeners.
         * Finally, point the driver's bpf cookie at the interface so
         * it will divert packets to bpf.
         */
        d->bd_bif = bp;
        d->bd_next = bp->bif_dlist;
        bp->bif_dlist = d;

        bp->bif_ifp->if_bpf = bp;

#ifdef __APPLE__
        if (bp->bif_ifp->if_set_bpf_tap)
                (*bp->bif_ifp->if_set_bpf_tap)(bp->bif_ifp, BPF_TAP_INPUT_OUTPUT, bpf_tap_callback);
#endif
}

/*
 * Detach a file from its interface.
 */
static void
bpf_detachd(d)
        struct bpf_d *d;
{
        struct bpf_d **p;
        struct bpf_if *bp;
#ifdef __APPLE__
        struct ifnet  *ifp;

        ifp = d->bd_bif->bif_ifp;

#endif

        bp = d->bd_bif;
        /*
         * Check if this descriptor had requested promiscuous mode.
         * If so, turn it off.
         */
        if (d->bd_promisc) {
                d->bd_promisc = 0;
                if (ifpromisc(bp->bif_ifp, 0))
                        /*
                         * Something is really wrong if we were able to put
                         * the driver into promiscuous mode, but can't
                         * take it out.
                         * Most likely the network interface is gone.
                         */
                        printf("bpf: ifpromisc failed");
        }
        /* Remove d from the interface's descriptor list. */
        p = &bp->bif_dlist;
        while (*p != d) {
                p = &(*p)->bd_next;
                if (*p == 0)
                        panic("bpf_detachd: descriptor not in list");
        }
        *p = (*p)->bd_next;
        if (bp->bif_dlist == 0) {
                /*
                 * Let the driver know that there are no more listeners.
                 */
                if (ifp->if_set_bpf_tap)
                        (*ifp->if_set_bpf_tap)(ifp, BPF_TAP_DISABLE, 0);
                d->bd_bif->bif_ifp->if_bpf = 0;
        }
        d->bd_bif = 0;
}


/*
 * Open ethernet device.  Returns ENXIO for illegal minor device number,
 * EBUSY if file is open by another process.
 */
/* ARGSUSED */
        int
bpfopen(dev, flags, fmt, p)
        dev_t dev;
        int flags;
        int fmt;
        struct proc *p;
{
        register struct bpf_d *d;

#ifdef __APPLE__
        /* new device nodes on demand when opening the last one */
        if (minor(dev) == nbpfilter - 1)
                bpf_make_dev_t(major(dev));

        if (minor(dev) >= nbpfilter)
                return (ENXIO);
        
        d = bpf_dtab[minor(dev)];

        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);
#else
        if (p->p_prison)
                return (EPERM);

        d = dev->si_drv1;
#endif
        /*
         * Each minor can be opened by only one process.  If the requested 
         * minor is in use, return EBUSY.
         */
#ifdef __APPLE__
        if (!D_ISFREE(d)) {
             thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
             return (EBUSY);
        }
        
        /* Mark "free" and do most initialization. */
        bzero((char *)d, sizeof(*d));
#else
        if (d)
                return (EBUSY);
        make_dev(&bpf_cdevsw, minor(dev), 0, 0, 0600, "bpf%d", lminor(dev));
        MALLOC(d, struct bpf_d *, sizeof(*d), M_BPF, M_WAITOK);
        bzero(d, sizeof(*d));
        dev->si_drv1 = d;
#endif
        d->bd_bufsize = bpf_bufsize;
        d->bd_sig = SIGIO;
        d->bd_seesent = 1;

#ifdef __APPLE__
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
#endif

        return (0);
}

/*
 * Close the descriptor by detaching it from its interface,
 * deallocating its buffers, and marking it free.
 */
/* ARGSUSED */
        int
bpfclose(dev, flags, fmt, p)
        dev_t dev;
        int flags;
        int fmt;
        struct proc *p;
{
        register struct bpf_d *d;
        register int s;
#ifdef __APPLE__
        struct bpf_d **bpf_dtab_schk;
#endif

#ifndef __APPLE__
        funsetown(d->bd_sigio);
#endif
        s = splimp();
#ifdef __APPLE__
again:
        d = bpf_dtab[minor(dev)];
        bpf_dtab_schk = bpf_dtab;
#endif
        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);

#ifdef __APPLE__
        /*
         * If someone grows bpf_dtab[] while we were waiting for the
         * funnel, then we will be pointing off into freed memory;
         * check to see if this is the case.
         */
        if (bpf_dtab_schk != bpf_dtab) {
                thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
                goto again;
        }
#endif

        if (d->bd_bif)
                bpf_detachd(d);
        splx(s);
#ifdef __APPLE__
        selthreadclear(&d->bd_sel);
#endif
        bpf_freed(d);
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
        return (0);
}

/*
 * Support for SunOS, which does not have tsleep.
 */
#if BSD < 199103
static
bpf_timeout(arg)
        caddr_t arg;
{
        boolean_t       funnel_state;
        struct bpf_d *d = (struct bpf_d *)arg;
        funnel_state = thread_funnel_set(network_flock, TRUE);
        d->bd_timedout = 1;
        wakeup(arg);
        (void) thread_funnel_set(network_flock, FALSE);
}

#define BPF_SLEEP(chan, pri, s, t) bpf_sleep((struct bpf_d *)chan)

int
bpf_sleep(d)
        register struct bpf_d *d;
{
        register int rto = d->bd_rtout;
        register int st;

        if (rto != 0) {
                d->bd_timedout = 0;
                timeout(bpf_timeout, (caddr_t)d, rto);
        }
        st = sleep((caddr_t)d, PRINET|PCATCH);
        if (rto != 0) {
                if (d->bd_timedout == 0)
                        untimeout(bpf_timeout, (caddr_t)d);
                else if (st == 0)
                        return EWOULDBLOCK;
        }
        return (st != 0) ? EINTR : 0;
}
#else
#define BPF_SLEEP tsleep
#endif

/*
 * Rotate the packet buffers in descriptor d.  Move the store buffer
 * into the hold slot, and the free buffer into the store slot.
 * Zero the length of the new store buffer.
 */
#define ROTATE_BUFFERS(d) \
        (d)->bd_hbuf = (d)->bd_sbuf; \
        (d)->bd_hlen = (d)->bd_slen; \
        (d)->bd_sbuf = (d)->bd_fbuf; \
        (d)->bd_slen = 0; \
        (d)->bd_fbuf = 0;
/*
 *  bpfread - read next chunk of packets from buffers
 */
        int
bpfread(dev, uio, ioflag)
        dev_t dev;
        struct uio *uio;
        int ioflag;
{
        register struct bpf_d *d;
        int error;
        int s;

        d = bpf_dtab[minor(dev)];

        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);

        /*
         * Restrict application to use a buffer the same size as
         * as kernel buffers.
         */
        if (uio->uio_resid != d->bd_bufsize) {
                thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
                return (EINVAL);
        }

        s = splimp();
        /*
         * If the hold buffer is empty, then do a timed sleep, which
         * ends when the timeout expires or when enough packets
         * have arrived to fill the store buffer.
         */
        while (d->bd_hbuf == 0) {
                if (d->bd_immediate && d->bd_slen != 0) {
                        /*
                         * A packet(s) either arrived since the previous
                         * read or arrived while we were asleep.
                         * Rotate the buffers and return what's here.
                         */
                        ROTATE_BUFFERS(d);
                        break;
                }

                /*
                 * No data is available, check to see if the bpf device
                 * is still pointed at a real interface.  If not, return
                 * ENXIO so that the userland process knows to rebind
                 * it before using it again.
                 */
                if (d->bd_bif == NULL) {
                        splx(s);
                        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
                        return (ENXIO);
                }
                
                if (ioflag & IO_NDELAY)
                        error = EWOULDBLOCK;
                else
                        error = BPF_SLEEP((caddr_t)d, PRINET|PCATCH, "bpf",
                                          d->bd_rtout);
                if (error == EINTR || error == ERESTART) {
                        splx(s);
                        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
                        return (error);
                }
                if (error == EWOULDBLOCK) {
                        /*
                         * On a timeout, return what's in the buffer,
                         * which may be nothing.  If there is something
                         * in the store buffer, we can rotate the buffers.
                         */
                        if (d->bd_hbuf)
                                /*
                                 * We filled up the buffer in between
                                 * getting the timeout and arriving
                                 * here, so we don't need to rotate.
                                 */
                                break;

                        if (d->bd_slen == 0) {
                                splx(s);
                                thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
                                return (0);
                        }
                        ROTATE_BUFFERS(d);
                        break;
                }
        }
        /*
         * At this point, we know we have something in the hold slot.
         */
        splx(s);

        /*
         * Move data from hold buffer into user space.
         * We know the entire buffer is transferred since
         * we checked above that the read buffer is bpf_bufsize bytes.
         */
        error = UIOMOVE(d->bd_hbuf, d->bd_hlen, UIO_READ, uio);

        s = splimp();
        d->bd_fbuf = d->bd_hbuf;
        d->bd_hbuf = 0;
        d->bd_hlen = 0;
        splx(s);
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
        return (error);
}


/*
 * If there are processes sleeping on this descriptor, wake them up.
 */
static inline void
bpf_wakeup(d)
        register struct bpf_d *d;
{
        wakeup((caddr_t)d);
        if (d->bd_async && d->bd_sig && d->bd_sigio)
                pgsigio(d->bd_sigio, d->bd_sig, 0);

#if BSD >= 199103
        selwakeup(&d->bd_sel);
#ifndef __APPLE__
        /* XXX */
        d->bd_sel.si_pid = 0;
#endif
#else
        if (d->bd_selproc) {
                selwakeup(d->bd_selproc, (int)d->bd_selcoll);
                d->bd_selcoll = 0;
                d->bd_selproc = 0;
        }
#endif
}

/* keep in sync with bpf_movein above: */
#define MAX_DATALINK_HDR_LEN    (sizeof(struct firewire_header))

        int
bpfwrite(dev, uio, ioflag)
        dev_t dev;
        struct uio *uio;
        int ioflag;
{
        register struct bpf_d *d;
        struct ifnet *ifp;
        struct mbuf *m;
        int error, s;
        char              dst_buf[SOCKADDR_HDR_LEN + MAX_DATALINK_HDR_LEN];
        int datlen;

        d = bpf_dtab[minor(dev)];

        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);
        
        if (d->bd_bif == 0) {
             thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
             return (ENXIO);
        }

        ifp = d->bd_bif->bif_ifp;

        if (uio->uio_resid == 0) {
             thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
             return (0);
        }
        ((struct sockaddr *)dst_buf)->sa_len = sizeof(dst_buf);
        error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, &m, 
                           (struct sockaddr *)dst_buf, &datlen);
        if (error) {
             thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
             return (error);
        }

        if (datlen > ifp->if_mtu) {
             thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
             return (EMSGSIZE);
        }

        if (d->bd_hdrcmplt) {
                ((struct sockaddr *)dst_buf)->sa_family = pseudo_AF_HDRCMPLT;
        }

        s = splnet();

        error = dlil_output(ifptodlt(ifp, PF_INET), m, 
                        (caddr_t) 0, (struct sockaddr *)dst_buf, 0);

        splx(s);
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
        /*
         * The driver frees the mbuf.
         */
        return (error);
}

/*
 * Reset a descriptor by flushing its packet buffer and clearing the
 * receive and drop counts.  Should be called at splimp.
 */
static void
reset_d(d)
        struct bpf_d *d;
{
        if (d->bd_hbuf) {
                /* Free the hold buffer. */
                d->bd_fbuf = d->bd_hbuf;
                d->bd_hbuf = 0;
        }
        d->bd_slen = 0;
        d->bd_hlen = 0;
        d->bd_rcount = 0;
        d->bd_dcount = 0;
}

/*
 *  FIONREAD            Check for read packet available.
 *  SIOCGIFADDR         Get interface address - convenient hook to driver.
 *  BIOCGBLEN           Get buffer len [for read()].
 *  BIOCSETF            Set ethernet read filter.
 *  BIOCFLUSH           Flush read packet buffer.
 *  BIOCPROMISC         Put interface into promiscuous mode.
 *  BIOCGDLT            Get link layer type.
 *  BIOCGETIF           Get interface name.
 *  BIOCSETIF           Set interface.
 *  BIOCSRTIMEOUT       Set read timeout.
 *  BIOCGRTIMEOUT       Get read timeout.
 *  BIOCGSTATS          Get packet stats.
 *  BIOCIMMEDIATE       Set immediate mode.
 *  BIOCVERSION         Get filter language version.
 *  BIOCGHDRCMPLT       Get "header already complete" flag
 *  BIOCSHDRCMPLT       Set "header already complete" flag
 *  BIOCGSEESENT        Get "see packets sent" flag
 *  BIOCSSEESENT        Set "see packets sent" flag
 */
/* ARGSUSED */
int
bpfioctl(dev, cmd, addr, flags, p)
        dev_t dev;
        u_long cmd;
        caddr_t addr;
        int flags;
        struct proc *p;
{
        register struct bpf_d *d;
        int s, error = 0;

        d = bpf_dtab[minor(dev)];

        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);

        switch (cmd) {

        default:
                error = EINVAL;
                break;

        /*
         * Check for read packet available.
         */
        case FIONREAD:
                {
                        int n;

                        s = splimp();
                        n = d->bd_slen;
                        if (d->bd_hbuf)
                                n += d->bd_hlen;
                        splx(s);

                        *(int *)addr = n;
                        break;
                }

        case SIOCGIFADDR:
                {
                        struct ifnet *ifp;

                        if (d->bd_bif == 0)
                                error = EINVAL;
                        else {
                                ifp = d->bd_bif->bif_ifp;
                                error = (*ifp->if_ioctl)(ifp, cmd, addr);
                        }
                        break;
                }

        /*
         * Get buffer len [for read()].
         */
        case BIOCGBLEN:
                *(u_int *)addr = d->bd_bufsize;
                break;

        /*
         * Set buffer length.
         */
        case BIOCSBLEN:
#if BSD < 199103
                error = EINVAL;
#else
                if (d->bd_bif != 0)
                        error = EINVAL;
                else {
                        register u_int size = *(u_int *)addr;

                        if (size > bpf_maxbufsize)
                                *(u_int *)addr = size = bpf_maxbufsize;
                        else if (size < BPF_MINBUFSIZE)
                                *(u_int *)addr = size = BPF_MINBUFSIZE;
                        d->bd_bufsize = size;
                }
#endif
                break;

        /*
         * Set link layer read filter.
         */
        case BIOCSETF:
                error = bpf_setf(d, (struct bpf_program *)addr);
                break;

        /*
         * Flush read packet buffer.
         */
        case BIOCFLUSH:
                s = splimp();
                reset_d(d);
                splx(s);
                break;

        /*
         * Put interface into promiscuous mode.
         */
        case BIOCPROMISC:
                if (d->bd_bif == 0) {
                        /*
                         * No interface attached yet.
                         */
                        error = EINVAL;
                        break;
                }
                s = splimp();
                if (d->bd_promisc == 0) {
                        error = ifpromisc(d->bd_bif->bif_ifp, 1);
                        if (error == 0)
                                d->bd_promisc = 1;
                }
                splx(s);
                break;

        /*
         * Get device parameters.
         */
        case BIOCGDLT:
                if (d->bd_bif == 0)
                        error = EINVAL;
                else
                        *(u_int *)addr = d->bd_bif->bif_dlt;
                break;

        /*
         * Get interface name.
         */
        case BIOCGETIF:
                if (d->bd_bif == 0)
                        error = EINVAL;
                else {
                        struct ifnet *const ifp = d->bd_bif->bif_ifp;
                        struct ifreq *const ifr = (struct ifreq *)addr;

                        snprintf(ifr->ifr_name, sizeof(ifr->ifr_name),
                            "%s%d", ifp->if_name, ifp->if_unit);
                }
                break;

        /*
         * Set interface.
         */
        case BIOCSETIF:
                error = bpf_setif(d, (struct ifreq *)addr);
                break;

        /*
         * Set read timeout.
         */
        case BIOCSRTIMEOUT:
                {
                        struct timeval *tv = (struct timeval *)addr;

                        /*
                         * Subtract 1 tick from tvtohz() since this isn't
                         * a one-shot timer.
                         */
                        if ((error = itimerfix(tv)) == 0)
                                d->bd_rtout = tvtohz(tv) - 1;
                        break;
                }

        /*
         * Get read timeout.
         */
        case BIOCGRTIMEOUT:
                {
                        struct timeval *tv = (struct timeval *)addr;

                        tv->tv_sec = d->bd_rtout / hz;
                        tv->tv_usec = (d->bd_rtout % hz) * tick;
                        break;
                }

        /*
         * Get packet stats.
         */
        case BIOCGSTATS:
                {
                        struct bpf_stat *bs = (struct bpf_stat *)addr;

                        bs->bs_recv = d->bd_rcount;
                        bs->bs_drop = d->bd_dcount;
                        break;
                }

        /*
         * Set immediate mode.
         */
        case BIOCIMMEDIATE:
                d->bd_immediate = *(u_int *)addr;
                break;

        case BIOCVERSION:
                {
                        struct bpf_version *bv = (struct bpf_version *)addr;

                        bv->bv_major = BPF_MAJOR_VERSION;
                        bv->bv_minor = BPF_MINOR_VERSION;
                        break;
                }

        /*
         * Get "header already complete" flag
         */
        case BIOCGHDRCMPLT:
                *(u_int *)addr = d->bd_hdrcmplt;
                break;

        /*
         * Set "header already complete" flag
         */
        case BIOCSHDRCMPLT:
                d->bd_hdrcmplt = *(u_int *)addr ? 1 : 0;
                break;

        /*
         * Get "see sent packets" flag
         */
        case BIOCGSEESENT:
                *(u_int *)addr = d->bd_seesent;
                break;

        /*
         * Set "see sent packets" flag
         */
        case BIOCSSEESENT:
                d->bd_seesent = *(u_int *)addr;
                break;

        case FIONBIO:           /* Non-blocking I/O */
                break;

        case FIOASYNC:          /* Send signal on receive packets */
                d->bd_async = *(int *)addr;
                break;
#ifndef __APPLE__
        case FIOSETOWN:
                error = fsetown(*(int *)addr, &d->bd_sigio);
                break;

        case FIOGETOWN:
                *(int *)addr = fgetown(d->bd_sigio);
                break;

        /* This is deprecated, FIOSETOWN should be used instead. */
        case TIOCSPGRP:
                error = fsetown(-(*(int *)addr), &d->bd_sigio);
                break;

        /* This is deprecated, FIOGETOWN should be used instead. */
        case TIOCGPGRP:
                *(int *)addr = -fgetown(d->bd_sigio);
                break;
#endif
        case BIOCSRSIG:         /* Set receive signal */
                {
                        u_int sig;

                        sig = *(u_int *)addr;

                        if (sig >= NSIG)
                                error = EINVAL;
                        else
                                d->bd_sig = sig;
                        break;
                }
        case BIOCGRSIG:
                *(u_int *)addr = d->bd_sig;
                break;
        }
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
        return (error);
}

/*
 * Set d's packet filter program to fp.  If this file already has a filter,
 * free it and replace it.  Returns EINVAL for bogus requests.
 */
static int
bpf_setf(d, fp)
        struct bpf_d *d;
        struct bpf_program *fp;
{
        struct bpf_insn *fcode, *old;
        u_int flen, size;
        int s;

        old = d->bd_filter;
        if (fp->bf_insns == 0) {
                if (fp->bf_len != 0)
                        return (EINVAL);
                s = splimp();
                d->bd_filter = 0;
                reset_d(d);
                splx(s);
                if (old != 0)
                        FREE((caddr_t)old, M_DEVBUF);
                return (0);
        }
        flen = fp->bf_len;
        if (flen > BPF_MAXINSNS)
                return (EINVAL);

        size = flen * sizeof(*fp->bf_insns);
        fcode = (struct bpf_insn *) _MALLOC(size, M_DEVBUF, M_WAIT);
#ifdef __APPLE__
        if (fcode == NULL)
                return (ENOBUFS);
#endif
        if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) == 0 &&
            bpf_validate(fcode, (int)flen)) {
                s = splimp();
                d->bd_filter = fcode;
                reset_d(d);
                splx(s);
                if (old != 0)
                        FREE((caddr_t)old, M_DEVBUF);

                return (0);
        }
        FREE((caddr_t)fcode, M_DEVBUF);
        return (EINVAL);
}

/*
 * Detach a file from its current interface (if attached at all) and attach
 * to the interface indicated by the name stored in ifr.
 * Return an errno or 0.
 */
static int
bpf_setif(d, ifr)
        struct bpf_d *d;
        struct ifreq *ifr;
{
        struct bpf_if *bp;
        int s, error;
        struct ifnet *theywant;

        theywant = ifunit(ifr->ifr_name);
        if (theywant == 0)
                return ENXIO;

        /*
         * Look through attached interfaces for the named one.
         */
        for (bp = bpf_iflist; bp != 0; bp = bp->bif_next) {
                struct ifnet *ifp = bp->bif_ifp;

                if (ifp == 0 || ifp != theywant)
                        continue;
                /*
                 * We found the requested interface.
                 * If it's not up, return an error.
                 * Allocate the packet buffers if we need to.
                 * If we're already attached to requested interface,
                 * just flush the buffer.
                 */
                if ((ifp->if_flags & IFF_UP) == 0)
                        return (ENETDOWN);

                if (d->bd_sbuf == 0) {
                        error = bpf_allocbufs(d);
                        if (error != 0)
                                return (error);
                }
                s = splimp();
                if (bp != d->bd_bif) {
                        if (d->bd_bif)
                                /*
                                 * Detach if attached to something else.
                                 */
                                bpf_detachd(d);

                        bpf_attachd(d, bp);
                }
                reset_d(d);
                splx(s);
                return (0);
        }
        /* Not found. */
        return (ENXIO);
}

/*
 * Support for select() and poll() system calls
 *
 * Return true iff the specific operation will not block indefinitely.
 * Otherwise, return false but make a note that a selwakeup() must be done.
 */
int
bpfpoll(dev, events, wql, p)
        register dev_t dev;
        int events;
        void * wql;
        struct proc *p;
{
        register struct bpf_d *d;
        register int s;
        int revents = 0;

        d = bpf_dtab[minor(dev)];

        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);
        /*
         * An imitation of the FIONREAD ioctl code.
         */
        if (d->bd_bif == NULL) {
                thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
                return (ENXIO);
        }

        s = splimp();
        if (events & (POLLIN | POLLRDNORM)) {
                if (d->bd_hlen != 0 || (d->bd_immediate && d->bd_slen != 0))
                        revents |= events & (POLLIN | POLLRDNORM);
                else
                        selrecord(p, &d->bd_sel, wql);
        }
        splx(s);
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
        return (revents);
}

/*
 * Incoming linkage from device drivers.  Process the packet pkt, of length
 * pktlen, which is stored in a contiguous buffer.  The packet is parsed
 * by each process' filter, and if accepted, stashed into the corresponding
 * buffer.
 */
void
bpf_tap(ifp, pkt, pktlen)
        struct ifnet *ifp;
        register u_char *pkt;
        register u_int pktlen;
{
        struct bpf_if *bp;
        register struct bpf_d *d;
        register u_int slen;
        /*
         * Note that the ipl does not have to be raised at this point.
         * The only problem that could arise here is that if two different
         * interfaces shared any data.  This is not the case.
         */
        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);
        bp = ifp->if_bpf;
#ifdef __APPLE__
        if (bp) {
#endif
        for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
                ++d->bd_rcount;
                slen = bpf_filter(d->bd_filter, pkt, pktlen, pktlen);
                if (slen != 0)
                        catchpacket(d, pkt, pktlen, slen, bcopy);
        }
#ifdef __APPLE__
    }
        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);
#endif
}

/*
 * Copy data from an mbuf chain into a buffer.  This code is derived
 * from m_copydata in sys/uipc_mbuf.c.
 */
static void
bpf_mcopy(src_arg, dst_arg, len)
        const void *src_arg;
        void *dst_arg;
        register size_t len;
{
        register const struct mbuf *m;
        register u_int count;
        u_char *dst;

        m = src_arg;
        dst = dst_arg;
        while (len > 0) {
                if (m == 0)
                        panic("bpf_mcopy");
                count = min(m->m_len, len);
                bcopy(mtod((struct mbuf *)m, void *), dst, count);
                m = m->m_next;
                dst += count;
                len -= count;
        }
}

/*
 * Incoming linkage from device drivers, when packet is in an mbuf chain.
 */
void
bpf_mtap(ifp, m)
        struct ifnet *ifp;
        struct mbuf *m;
{
        struct bpf_if *bp = ifp->if_bpf;
        struct bpf_d *d;
        u_int pktlen, slen;
        struct mbuf *m0;

        pktlen = 0;
        for (m0 = m; m0 != 0; m0 = m0->m_next)
                pktlen += m0->m_len;

        for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
                if (!d->bd_seesent && (m->m_pkthdr.rcvif == NULL))
                        continue;
                ++d->bd_rcount;
                slen = bpf_filter(d->bd_filter, (u_char *)m, pktlen, 0);
                if (slen != 0)
                        catchpacket(d, (u_char *)m, pktlen, slen, bpf_mcopy);
        }
}

/*
 * Move the packet data from interface memory (pkt) into the
 * store buffer.  Return 1 if it's time to wakeup a listener (buffer full),
 * otherwise 0.  "copy" is the routine called to do the actual data
 * transfer.  bcopy is passed in to copy contiguous chunks, while
 * bpf_mcopy is passed in to copy mbuf chains.  In the latter case,
 * pkt is really an mbuf.
 */
static void
catchpacket(d, pkt, pktlen, snaplen, cpfn)
        register struct bpf_d *d;
        register u_char *pkt;
        register u_int pktlen, snaplen;
        register void (*cpfn) __P((const void *, void *, size_t));
{
        register struct bpf_hdr *hp;
        register int totlen, curlen;
        register int hdrlen = d->bd_bif->bif_hdrlen;
        /*
         * Figure out how many bytes to move.  If the packet is
         * greater or equal to the snapshot length, transfer that
         * much.  Otherwise, transfer the whole packet (unless
         * we hit the buffer size limit).
         */
        totlen = hdrlen + min(snaplen, pktlen);
        if (totlen > d->bd_bufsize)
                totlen = d->bd_bufsize;

        /*
         * Round up the end of the previous packet to the next longword.
         */
        curlen = BPF_WORDALIGN(d->bd_slen);
        if (curlen + totlen > d->bd_bufsize) {
                /*
                 * This packet will overflow the storage buffer.
                 * Rotate the buffers if we can, then wakeup any
                 * pending reads.
                 */
                if (d->bd_fbuf == 0) {
                        /*
                         * We haven't completed the previous read yet,
                         * so drop the packet.
                         */
                        ++d->bd_dcount;
                        return;
                }
                ROTATE_BUFFERS(d);
                bpf_wakeup(d);
                curlen = 0;
        }
        else if (d->bd_immediate)
                /*
                 * Immediate mode is set.  A packet arrived so any
                 * reads should be woken up.
                 */
                bpf_wakeup(d);

        /*
         * Append the bpf header.
         */
        hp = (struct bpf_hdr *)(d->bd_sbuf + curlen);
#if BSD >= 199103
        microtime(&hp->bh_tstamp);
#elif defined(sun)
        uniqtime(&hp->bh_tstamp);
#else
        hp->bh_tstamp = time;
#endif
        hp->bh_datalen = pktlen;
        hp->bh_hdrlen = hdrlen;
        /*
         * Copy the packet data into the store buffer and update its length.
         */
        (*cpfn)(pkt, (u_char *)hp + hdrlen, (hp->bh_caplen = totlen - hdrlen));
        d->bd_slen = curlen + totlen;
}

/*
 * Initialize all nonzero fields of a descriptor.
 */
static int
bpf_allocbufs(d)
        register struct bpf_d *d;
{
        d->bd_fbuf = (caddr_t) _MALLOC(d->bd_bufsize, M_DEVBUF, M_WAIT);
        if (d->bd_fbuf == 0)
                return (ENOBUFS);

        d->bd_sbuf = (caddr_t) _MALLOC(d->bd_bufsize, M_DEVBUF, M_WAIT);
        if (d->bd_sbuf == 0) {
                FREE(d->bd_fbuf, M_DEVBUF);
                return (ENOBUFS);
        }
        d->bd_slen = 0;
        d->bd_hlen = 0;
        return (0);
}

/*
 * Free buffers currently in use by a descriptor.
 * Called on close.
 */
static void
bpf_freed(d)
        register struct bpf_d *d;
{
        /*
         * We don't need to lock out interrupts since this descriptor has
         * been detached from its interface and it yet hasn't been marked
         * free.
         */
        if (d->bd_sbuf != 0) {
                FREE(d->bd_sbuf, M_DEVBUF);
                if (d->bd_hbuf != 0)
                        FREE(d->bd_hbuf, M_DEVBUF);
                if (d->bd_fbuf != 0)
                        FREE(d->bd_fbuf, M_DEVBUF);
        }
        if (d->bd_filter)
                FREE((caddr_t)d->bd_filter, M_DEVBUF);

        D_MARKFREE(d);
}

/*
 * Attach an interface to bpf.  driverp is a pointer to a (struct bpf_if *)
 * in the driver's softc; dlt is the link layer type; hdrlen is the fixed
 * size of the link header (variable length headers not yet supported).
 */
void
bpfattach(ifp, dlt, hdrlen)
        struct ifnet *ifp;
        u_int dlt, hdrlen;
{
        struct bpf_if *bp;
        int i;
        bp = (struct bpf_if *) _MALLOC(sizeof(*bp), M_DEVBUF, M_WAIT);
        if (bp == 0)
                panic("bpfattach");

        bp->bif_dlist = 0;
        bp->bif_ifp = ifp;
        bp->bif_dlt = dlt;

        bp->bif_next = bpf_iflist;
        bpf_iflist = bp;

        bp->bif_ifp->if_bpf = 0;

        /*
         * Compute the length of the bpf header.  This is not necessarily
         * equal to SIZEOF_BPF_HDR because we want to insert spacing such
         * that the network layer header begins on a longword boundary (for
         * performance reasons and to alleviate alignment restrictions).
         */
        bp->bif_hdrlen = BPF_WORDALIGN(hdrlen + SIZEOF_BPF_HDR) - hdrlen;

#ifndef __APPLE__
        if (bootverbose)
                printf("bpf: %s%d attached\n", ifp->if_name, ifp->if_unit);
#endif
}

/*
 * Detach bpf from an interface.  This involves detaching each descriptor
 * associated with the interface, and leaving bd_bif NULL.  Notify each
 * descriptor as it's detached so that any sleepers wake up and get
 * ENXIO.
 */
void
bpfdetach(ifp)
        struct ifnet *ifp;
{
        struct bpf_if   *bp, *bp_prev;
        struct bpf_d    *d;
        int     s;

        s = splimp();

        /* Locate BPF interface information */
        bp_prev = NULL;
        for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
                if (ifp == bp->bif_ifp)
                        break;
                bp_prev = bp;
        }

#ifdef __APPLE__
        /* Check for no BPF interface information */
        if (bp == NULL) {
                return;
        }
#endif

        /* Interface wasn't attached */
        if (bp->bif_ifp == NULL) {
                splx(s);
#ifndef __APPLE__
                printf("bpfdetach: %s%d was not attached\n", ifp->if_name,
                    ifp->if_unit);
#endif
                return;
        }

        while ((d = bp->bif_dlist) != NULL) {
                bpf_detachd(d);
                bpf_wakeup(d);
        }

        if (bp_prev) {
                bp_prev->bif_next = bp->bif_next;
        } else {
                bpf_iflist = bp->bif_next;
        }

        FREE(bp, M_DEVBUF);

        splx(s);
}

void
bpf_init(unused)
        void *unused;
{
#ifdef __APPLE__
        int     i;
        int     maj;

        if (!bpf_devsw_installed ) {
                bpf_devsw_installed = 1;
                maj = cdevsw_add(CDEV_MAJOR, &bpf_cdevsw);
                if (maj == -1) {
                        printf("bpf_init: failed to allocate a major number!\n");
                        nbpfilter = 0;
                        return;
                }
                if (bpf_dtab_grow(NBPFILTER) == 0) {
                        printf("bpf_init: failed to allocate bpf_dtab\n");
                        return;
                }
                for (i = 0 ; i < NBPFILTER; i++)
                        bpf_make_dev_t(maj);
        }
#else
        cdevsw_add(&bpf_cdevsw);
#endif
}

#ifndef __APPLE__
SYSINIT(bpfdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,bpf_drvinit,NULL)
#endif

#else /* !BPF */
#ifndef __APPLE__
/*
 * NOP stubs to allow bpf-using drivers to load and function.
 *
 * A 'better' implementation would allow the core bpf functionality
 * to be loaded at runtime.
 */

void
bpf_tap(ifp, pkt, pktlen)
        struct ifnet *ifp;
        register u_char *pkt;
        register u_int pktlen;
{
}

void
bpf_mtap(ifp, m)
        struct ifnet *ifp;
        struct mbuf *m;
{
}

void
bpfattach(ifp, dlt, hdrlen)
        struct ifnet *ifp;
        u_int dlt, hdrlen;
{
}

void
bpfdetach(ifp)
        struct ifnet *ifp;
{
}

u_int
bpf_filter(pc, p, wirelen, buflen)
        register const struct bpf_insn *pc;
        register u_char *p;
        u_int wirelen;
        register u_int buflen;
{
        return -1;      /* "no filter" behaviour */
}
#endif /* !defined(__APPLE__) */
#endif /* NBPFILTER > 0 */