freebsd-dev/sys/net/bpf.c

/*
 * 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
 *
 * $Id: bpf.c,v 1.36 1997/11/18 16:29:53 bde Exp $
 */

#include "bpfilter.h"

#if NBPFILTER > 0

#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>

#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 "opt_devfs.h"

#ifdef DEVFS
#include <sys/devfsext.h>
#endif /*DEVFS*/


/*
 * 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, "");

/*
 *  bpf_iflist is the list of interfaces; each corresponds to an ifnet
 *  bpf_dtab holds the descriptors, indexed by minor device #
 */
static struct bpf_if	*bpf_iflist;
static struct bpf_d	bpf_dtab[NBPFILTER];
static int		bpf_dtab_init;

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_ifname __P((struct ifnet *, struct ifreq *));
static void	bpf_mcopy __P((const void *, void *, u_int));
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 *, u_int)));
static void	reset_d __P((struct bpf_d *));
static int	 bpf_setf __P((struct bpf_d *, struct bpf_program *));

static	d_open_t	bpfopen;
static	d_close_t	bpfclose;
static	d_read_t	bpfread;
static	d_write_t	bpfwrite;
static	d_ioctl_t	bpfioctl;
static	d_poll_t	bpfpoll;

#define CDEV_MAJOR 23
static struct cdevsw bpf_cdevsw = 
 	{ bpfopen,	bpfclose,	bpfread,	bpfwrite,	/*23*/
 	  bpfioctl,	nostop,		nullreset,	nodevtotty,/* bpf */
 	  bpfpoll,	nommap,		NULL,	"bpf",	NULL,	-1 };


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_NULL:
		sockp->sa_family = AF_UNSPEC;
		hlen = 0;
		break;

	default:
		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);
}

/*
 * 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;
}

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

	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.
			 */
			panic("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.
		 */
		d->bd_bif->bif_ifp->if_bpf = 0;
	d->bd_bif = 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)

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

	if (minor(dev) >= NBPFILTER)
		return (ENXIO);
	/*
	 * Each minor can be opened by only one process.  If the requested
	 * minor is in use, return EBUSY.
	 */
	d = &bpf_dtab[minor(dev)];
	if (!D_ISFREE(d))
		return (EBUSY);

	/* Mark "free" and do most initialization. */
	bzero((char *)d, sizeof(*d));
	d->bd_bufsize = bpf_bufsize;
	d->bd_sig = SIGIO;

	return (0);
}

/*
 * Close the descriptor by detaching it from its interface,
 * deallocating its buffers, and marking it free.
 */
/* ARGSUSED */
static	int
bpfclose(dev, flags, fmt, p)
	dev_t dev;
	int flags;
	int fmt;
	struct proc *p;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	register int s;

	s = splimp();
	if (d->bd_bif)
		bpf_detachd(d);
	splx(s);
	bpf_freed(d);

	return (0);
}

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

#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
 */
static	int
bpfread(dev, uio, ioflag)
	dev_t dev;
	register struct uio *uio;
	int ioflag;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	int error;
	int s;

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

	return (error);
}


/*
 * If there are processes sleeping on this descriptor, wake them up.
 */
static inline void
bpf_wakeup(d)
	register struct bpf_d *d;
{
	struct proc *p;

	wakeup((caddr_t)d);
	if (d->bd_async && d->bd_sig)
		if (d->bd_pgid > 0)
			gsignal (d->bd_pgid, d->bd_sig);
		else if (p = pfind (-d->bd_pgid))
			psignal (p, d->bd_sig);

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

static	int
bpfwrite(dev, uio, ioflag)
	dev_t dev;
	struct uio *uio;
	int ioflag;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	struct ifnet *ifp;
	struct mbuf *m;
	int error, s;
	static struct sockaddr dst;
	int datlen;

	if (d->bd_bif == 0)
		return (ENXIO);

	ifp = d->bd_bif->bif_ifp;

	if (uio->uio_resid == 0)
		return (0);

	error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, &m, &dst, &datlen);
	if (error)
		return (error);

	if (datlen > ifp->if_mtu)
		return (EMSGSIZE);

	s = splnet();
#if BSD >= 199103
	error = (*ifp->if_output)(ifp, m, &dst, (struct rtentry *)0);
#else
	error = (*ifp->if_output)(ifp, m, &dst);
#endif
	splx(s);
	/*
	 * 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.
 */
/* ARGSUSED */
static	int
bpfioctl(dev, cmd, addr, flags, p)
	dev_t dev;
	int cmd;
	caddr_t addr;
	int flags;
	struct proc *p;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	int s, error = 0;

	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;

	/*
	 * Set interface name.
	 */
	case BIOCGETIF:
		if (d->bd_bif == 0)
			error = EINVAL;
		else
			bpf_ifname(d->bd_bif->bif_ifp, (struct ifreq *)addr);
		break;

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

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

			/* Compute number of milliseconds. */
			msec = tv->tv_sec * 1000 + tv->tv_usec / 1000;
			/* Scale milliseconds to ticks.  Assume hard
			   clock has millisecond or greater resolution
			   (i.e. tick >= 1000).  For 10ms hardclock,
			   tick/1000 = 10, so rtout<-msec/10. */
			d->bd_rtout = msec / (tick / 1000);
			break;
		}

	/*
	 * Get read timeout.
	 */
	case BIOCGRTIMEOUT:
		{
			struct timeval *tv = (struct timeval *)addr;
			u_long msec = d->bd_rtout;

			msec *= tick / 1000;
			tv->tv_sec = msec / 1000;
			tv->tv_usec = msec % 1000;
			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;
		}

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

	case FIOASYNC:		/* Send signal on receive packets */
		d->bd_async = *(int *)addr;
		break;

/* N.B.  ioctl (FIOSETOWN) and fcntl (F_SETOWN) both end up doing the
   equivalent of a TIOCSPGRP and hence end up here.  *However* TIOCSPGRP's arg
   is a process group if it's positive and a process id if it's negative.  This
   is exactly the opposite of what the other two functions want!  Therefore
   there is code in ioctl and fcntl to negate the arg before calling here. */

	case TIOCSPGRP:		/* Process or group to send signals to */
		d->bd_pgid = *(int *)addr;
		break;

	case TIOCGPGRP:
		*(int *)addr = d->bd_pgid;
		break;

	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;
	}
	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_WAITOK);
	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);
}

/*
 * Convert an interface name plus unit number of an ifp to a single
 * name which is returned in the ifr.
 */
static void
bpf_ifname(ifp, ifr)
	struct ifnet *ifp;
	struct ifreq *ifr;
{
	char *s = ifp->if_name;
	char *d = ifr->ifr_name;

	while (*d++ = *s++)
		continue;
	d--; /* back to the null */
	/* XXX Assume that unit number is less than 10. */
	*d++ = ifp->if_unit + '0';
	*d = '\0';
}

/*
 * 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, p)
	register dev_t dev;
	int events;
	struct proc *p;
{
	register struct bpf_d *d;
	register int s;
	int revents = 0;

	/*
	 * An imitation of the FIONREAD ioctl code.
	 */
	d = &bpf_dtab[minor(dev)];

	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);

	splx(s);
	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.
	 */
	bp = ifp->if_bpf;
	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);
	}
}

/*
 * 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 u_int 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(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) {
		++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 *, u_int));
{
	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_WAITOK);
	if (d->bd_fbuf == 0)
		return (ENOBUFS);

	d->bd_sbuf = (caddr_t)malloc(d->bd_bufsize, M_DEVBUF, M_WAITOK);
	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_DONTWAIT);
	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;

	/*
	 * Mark all the descriptors free if this hasn't been done.
	 */
	if (!bpf_dtab_init) {
		for (i = 0; i < NBPFILTER; ++i)
			D_MARKFREE(&bpf_dtab[i]);
		bpf_dtab_init = 1;
	}

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

#ifdef DEVFS
static	void *bpf_devfs_token[NBPFILTER];
#endif

static bpf_devsw_installed = 0;

static void bpf_drvinit __P((void *unused));
static void
bpf_drvinit(unused)
	void *unused;
{
	dev_t dev;
#ifdef DEVFS
	int i;
#endif

	if( ! bpf_devsw_installed ) {
		dev = makedev(CDEV_MAJOR, 0);
		cdevsw_add(&dev,&bpf_cdevsw, NULL);
		bpf_devsw_installed = 1;
#ifdef DEVFS

		for ( i = 0 ; i < NBPFILTER ; i++ ) {
			bpf_devfs_token[i] =
				devfs_add_devswf(&bpf_cdevsw, i, DV_CHR, 0, 0, 
						 0600, "bpf%d", i);
		}
#endif
    	}
}

SYSINIT(bpfdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,bpf_drvinit,NULL)

#endif