Expand PMF_FN_* macros.

[netbsd-mini2440.git] / sys / net / bpf.c

/*      $NetBSD: bpf.c,v 1.149 2009/12/09 21:32:59 dsl Exp $    */

/*
 * 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. 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       8.4 (Berkeley) 1/9/95
 * static char rcsid[] =
 * "Header: bpf.c,v 1.67 96/09/26 22:00:52 leres Exp ";
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: bpf.c,v 1.149 2009/12/09 21:32:59 dsl Exp $");

#if defined(_KERNEL_OPT)
#include "opt_bpf.h"
#include "sl.h"
#include "strip.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/buf.h>
#include <sys/time.h>
#include <sys/proc.h>
#include <sys/ioctl.h>
#include <sys/conf.h>
#include <sys/vnode.h>
#include <sys/queue.h>
#include <sys/stat.h>

#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/tty.h>
#include <sys/uio.h>

#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/poll.h>
#include <sys/sysctl.h>
#include <sys/kauth.h>

#include <net/if.h>
#include <net/slip.h>

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

#include <net/if_arc.h>
#include <net/if_ether.h>

#include <netinet/in.h>
#include <netinet/if_inarp.h>


#include <compat/sys/sockio.h>

#ifndef BPF_BUFSIZE
/*
 * 4096 is too small for FDDI frames. 8192 is too small for gigabit Ethernet
 * jumbos (circa 9k), ATM, or Intel gig/10gig ethernet jumbos (16k).
 */
# define BPF_BUFSIZE 32768
#endif

#define PRINET  26                      /* interruptible */

/*
 * The default read buffer size, and limit for BIOCSBLEN, is sysctl'able.
 * XXX the default values should be computed dynamically based
 * on available memory size and available mbuf clusters.
 */
int bpf_bufsize = BPF_BUFSIZE;
int bpf_maxbufsize = BPF_DFLTBUFSIZE;   /* XXX set dynamically, see above */


/*
 * Global BPF statistics returned by net.bpf.stats sysctl.
 */
struct bpf_stat bpf_gstats;

/*
 * Use a mutex to avoid a race condition between gathering the stats/peers
 * and opening/closing the device.
 */
static kmutex_t bpf_mtx;

/*
 *  bpf_iflist is the list of interfaces; each corresponds to an ifnet
 *  bpf_dtab holds the descriptors, indexed by minor device #
 */
struct bpf_if   *bpf_iflist;
LIST_HEAD(, bpf_d) bpf_list;

static int      bpf_allocbufs(struct bpf_d *);
static void     bpf_deliver(struct bpf_if *,
                            void *(*cpfn)(void *, const void *, size_t),
                            void *, u_int, u_int, struct ifnet *);
static void     bpf_freed(struct bpf_d *);
static void     bpf_ifname(struct ifnet *, struct ifreq *);
static void     *bpf_mcpy(void *, const void *, size_t);
static int      bpf_movein(struct uio *, int, int,
                                struct mbuf **, struct sockaddr *);
static void     bpf_attachd(struct bpf_d *, struct bpf_if *);
static void     bpf_detachd(struct bpf_d *);
static int      bpf_setif(struct bpf_d *, struct ifreq *);
static void     bpf_timed_out(void *);
static inline void
                bpf_wakeup(struct bpf_d *);
static void     catchpacket(struct bpf_d *, u_char *, u_int, u_int,
    void *(*)(void *, const void *, size_t), struct timespec *);
static void     reset_d(struct bpf_d *);
static int      bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *);
static int      bpf_setdlt(struct bpf_d *, u_int);

static int      bpf_read(struct file *, off_t *, struct uio *, kauth_cred_t,
    int);
static int      bpf_write(struct file *, off_t *, struct uio *, kauth_cred_t,
    int);
static int      bpf_ioctl(struct file *, u_long, void *);
static int      bpf_poll(struct file *, int);
static int      bpf_stat(struct file *, struct stat *);
static int      bpf_close(struct file *);
static int      bpf_kqfilter(struct file *, struct knote *);
static void     bpf_softintr(void *);

static const struct fileops bpf_fileops = {
        .fo_read = bpf_read,
        .fo_write = bpf_write,
        .fo_ioctl = bpf_ioctl,
        .fo_fcntl = fnullop_fcntl,
        .fo_poll = bpf_poll,
        .fo_stat = bpf_stat,
        .fo_close = bpf_close,
        .fo_kqfilter = bpf_kqfilter,
        .fo_restart = fnullop_restart,
};

dev_type_open(bpfopen);

const struct cdevsw bpf_cdevsw = {
        bpfopen, noclose, noread, nowrite, noioctl,
        nostop, notty, nopoll, nommap, nokqfilter, D_OTHER
};

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

        /*
         * 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;
                align = 0;
                break;

        case DLT_PPP:
                sockp->sa_family = AF_UNSPEC;
                hlen = 0;
                align = 0;
                break;

        case DLT_EN10MB:
                sockp->sa_family = AF_UNSPEC;
                /* XXX Would MAXLINKHDR be better? */
                /* 6(dst)+6(src)+2(type) */
                hlen = sizeof(struct ether_header);
                align = 2;
                break;

        case DLT_ARCNET:
                sockp->sa_family = AF_UNSPEC;
                hlen = ARC_HDRLEN;
                align = 5;
                break;

        case DLT_FDDI:
                sockp->sa_family = AF_LINK;
                /* XXX 4(FORMAC)+6(dst)+6(src) */
                hlen = 16;
                align = 0;
                break;

        case DLT_ECONET:
                sockp->sa_family = AF_UNSPEC;
                hlen = 6;
                align = 2;
                break;

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

        default:
                return (EIO);
        }

        len = uio->uio_resid;
        /*
         * If there aren't enough bytes for a link level header or the
         * packet length exceeds the interface mtu, return an error.
         */
        if (len < hlen || len - hlen > mtu)
                return (EMSGSIZE);

        /*
         * XXX Avoid complicated buffer chaining ---
         * bail if it won't fit in a single mbuf.
         * (Take into account possible alignment bytes)
         */
        if ((unsigned)len > MCLBYTES - align)
                return (EIO);

        m = m_gethdr(M_WAIT, MT_DATA);
        m->m_pkthdr.rcvif = 0;
        m->m_pkthdr.len = len - hlen;
        if (len > MHLEN - align) {
                m_clget(m, M_WAIT);
                if ((m->m_flags & M_EXT) == 0) {
                        error = ENOBUFS;
                        goto bad;
                }
        }

        /* Insure the data is properly aligned */
        if (align > 0) {
                m->m_data += align;
                m->m_len -= align;
        }

        error = uiomove(mtod(m, void *), len, uio);
        if (error)
                goto bad;
        if (hlen != 0) {
                memcpy(sockp->sa_data, mtod(m, void *), hlen);
                m->m_data += hlen; /* XXX */
                len -= hlen;
        }
        m->m_len = len;
        *mp = m;
        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 splnet.
 */
static void
bpf_attachd(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_driverp = bp;
}

/*
 * Detach a file from its interface.
 */
static void
bpf_detachd(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) {
                int error;

                d->bd_promisc = 0;
                /*
                 * Take device out of promiscuous mode.  Since we were
                 * able to enter promiscuous mode, we should be able
                 * to turn it off.  But we can get an error if
                 * the interface was configured down, so only panic
                 * if we don't get an unexpected error.
                 */
                error = ifpromisc(bp->bif_ifp, 0);
                if (error && error != EINVAL)
                        panic("%s: ifpromisc failed: %d", __func__, error);
        }
        /* Remove d from the interface's descriptor list. */
        p = &bp->bif_dlist;
        while (*p != d) {
                p = &(*p)->bd_next;
                if (*p == 0)
                        panic("%s: descriptor not in list", __func__);
        }
        *p = (*p)->bd_next;
        if (bp->bif_dlist == 0)
                /*
                 * Let the driver know that there are no more listeners.
                 */
                *d->bd_bif->bif_driverp = 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.
 */

/*
 * bpfilterattach() is called at boot time.
 */
/* ARGSUSED */
void
bpfilterattach(int n)
{
        mutex_init(&bpf_mtx, MUTEX_DEFAULT, IPL_NONE);

        mutex_enter(&bpf_mtx);
        LIST_INIT(&bpf_list);
        mutex_exit(&bpf_mtx);

        bpf_gstats.bs_recv = 0;
        bpf_gstats.bs_drop = 0;
        bpf_gstats.bs_capt = 0;
}

/*
 * Open ethernet device. Clones.
 */
/* ARGSUSED */
int
bpfopen(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct bpf_d *d;
        struct file *fp;
        int error, fd;

        /* falloc() will use the descriptor for us. */
        if ((error = fd_allocfile(&fp, &fd)) != 0)
                return error;

        d = malloc(sizeof(*d), M_DEVBUF, M_WAITOK|M_ZERO);
        d->bd_bufsize = bpf_bufsize;
        d->bd_seesent = 1;
        d->bd_pid = l->l_proc->p_pid;
        getnanotime(&d->bd_btime);
        d->bd_atime = d->bd_mtime = d->bd_btime;
        callout_init(&d->bd_callout, 0);
        selinit(&d->bd_sel);
        d->bd_sih = softint_establish(SOFTINT_CLOCK, bpf_softintr, d);

        mutex_enter(&bpf_mtx);
        LIST_INSERT_HEAD(&bpf_list, d, bd_list);
        mutex_exit(&bpf_mtx);

        return fd_clone(fp, fd, flag, &bpf_fileops, d);
}

/*
 * Close the descriptor by detaching it from its interface,
 * deallocating its buffers, and marking it free.
 */
/* ARGSUSED */
static int
bpf_close(struct file *fp)
{
        struct bpf_d *d = fp->f_data;
        int s;

        KERNEL_LOCK(1, NULL);

        /*
         * Refresh the PID associated with this bpf file.
         */
        d->bd_pid = curproc->p_pid;

        s = splnet();
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        d->bd_state = BPF_IDLE;
        if (d->bd_bif)
                bpf_detachd(d);
        splx(s);
        bpf_freed(d);
        mutex_enter(&bpf_mtx);
        LIST_REMOVE(d, bd_list);
        mutex_exit(&bpf_mtx);
        callout_destroy(&d->bd_callout);
        seldestroy(&d->bd_sel);
        softint_disestablish(d->bd_sih);
        free(d, M_DEVBUF);
        fp->f_data = NULL;

        KERNEL_UNLOCK_ONE(NULL);

        return (0);
}

/*
 * 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
bpf_read(struct file *fp, off_t *offp, struct uio *uio,
    kauth_cred_t cred, int flags)
{
        struct bpf_d *d = fp->f_data;
        int timed_out;
        int error;
        int s;

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

        KERNEL_LOCK(1, NULL);
        s = splnet();
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        timed_out = (d->bd_state == BPF_TIMED_OUT);
        d->bd_state = BPF_IDLE;
        /*
         * 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 (fp->f_flag & FNONBLOCK) {
                        if (d->bd_slen == 0) {
                                splx(s);
                                KERNEL_UNLOCK_ONE(NULL);
                                return (EWOULDBLOCK);
                        }
                        ROTATE_BUFFERS(d);
                        break;
                }

                if ((d->bd_immediate || timed_out) && 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;
                }
                error = tsleep(d, PRINET|PCATCH, "bpf",
                                d->bd_rtout);
                if (error == EINTR || error == ERESTART) {
                        splx(s);
                        KERNEL_UNLOCK_ONE(NULL);
                        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);
                                KERNEL_UNLOCK_ONE(NULL);
                                return (0);
                        }
                        ROTATE_BUFFERS(d);
                        break;
                }
                if (error != 0)
                        goto done;
        }
        /*
         * 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);

        s = splnet();
        d->bd_fbuf = d->bd_hbuf;
        d->bd_hbuf = 0;
        d->bd_hlen = 0;
done:
        splx(s);
        KERNEL_UNLOCK_ONE(NULL);
        return (error);
}


/*
 * If there are processes sleeping on this descriptor, wake them up.
 */
static inline void
bpf_wakeup(struct bpf_d *d)
{
        wakeup(d);
        if (d->bd_async)
                softint_schedule(d->bd_sih);
        selnotify(&d->bd_sel, 0, 0);
}

static void
bpf_softintr(void *cookie)
{
        struct bpf_d *d;

        d = cookie;
        if (d->bd_async)
                fownsignal(d->bd_pgid, SIGIO, 0, 0, NULL);
}

static void
bpf_timed_out(void *arg)
{
        struct bpf_d *d = arg;
        int s;

        s = splnet();
        if (d->bd_state == BPF_WAITING) {
                d->bd_state = BPF_TIMED_OUT;
                if (d->bd_slen != 0)
                        bpf_wakeup(d);
        }
        splx(s);
}


static int
bpf_write(struct file *fp, off_t *offp, struct uio *uio,
    kauth_cred_t cred, int flags)
{
        struct bpf_d *d = fp->f_data;
        struct ifnet *ifp;
        struct mbuf *m;
        int error, s;
        static struct sockaddr_storage dst;

        m = NULL;       /* XXX gcc */

        KERNEL_LOCK(1, NULL);

        if (d->bd_bif == 0) {
                KERNEL_UNLOCK_ONE(NULL);
                return (ENXIO);
        }
        getnanotime(&d->bd_mtime);

        ifp = d->bd_bif->bif_ifp;

        if (uio->uio_resid == 0) {
                KERNEL_UNLOCK_ONE(NULL);
                return (0);
        }

        error = bpf_movein(uio, (int)d->bd_bif->bif_dlt, ifp->if_mtu, &m,
                (struct sockaddr *) &dst);
        if (error) {
                KERNEL_UNLOCK_ONE(NULL);
                return (error);
        }

        if (m->m_pkthdr.len > ifp->if_mtu) {
                KERNEL_UNLOCK_ONE(NULL);
                m_freem(m);
                return (EMSGSIZE);
        }

        if (d->bd_hdrcmplt)
                dst.ss_family = pseudo_AF_HDRCMPLT;

        s = splsoftnet();
        error = (*ifp->if_output)(ifp, m, (struct sockaddr *) &dst, NULL);
        splx(s);
        KERNEL_UNLOCK_ONE(NULL);
        /*
         * 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 splnet.
 */
static void
reset_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;
        d->bd_ccount = 0;
}

/*
 *  FIONREAD            Check for read packet available.
 *  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.
 */
/* ARGSUSED */
static int
bpf_ioctl(struct file *fp, u_long cmd, void *addr)
{
        struct bpf_d *d = fp->f_data;
        int s, error = 0;

        /*
         * Refresh the PID associated with this bpf file.
         */
        KERNEL_LOCK(1, NULL);
        d->bd_pid = curproc->p_pid;

        s = splnet();
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        d->bd_state = BPF_IDLE;
        splx(s);

        switch (cmd) {

        default:
                error = EINVAL;
                break;

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

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

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

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

        /*
         * Set buffer length.
         */
        case BIOCSBLEN:
                if (d->bd_bif != 0)
                        error = EINVAL;
                else {
                        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;
                }
                break;

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

        /*
         * Flush read packet buffer.
         */
        case BIOCFLUSH:
                s = splnet();
                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 = splnet();
                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 a list of supported device parameters.
         */
        case BIOCGDLTLIST:
                if (d->bd_bif == 0)
                        error = EINVAL;
                else
                        error = bpf_getdltlist(d, addr);
                break;

        /*
         * Set device parameters.
         */
        case BIOCSDLT:
                if (d->bd_bif == 0)
                        error = EINVAL;
                else
                        error = bpf_setdlt(d, *(u_int *)addr);
                break;

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

        /*
         * Set interface.
         */
#ifdef OBIOCSETIF
        case OBIOCSETIF:
#endif
        case BIOCSETIF:
                error = bpf_setif(d, addr);
                break;

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

                        /* Compute number of ticks. */
                        d->bd_rtout = tv->tv_sec * hz + tv->tv_usec / tick;
                        if ((d->bd_rtout == 0) && (tv->tv_usec != 0))
                                d->bd_rtout = 1;
                        break;
                }

#ifdef BIOCGORTIMEOUT
        /*
         * Get read timeout.
         */
        case BIOCGORTIMEOUT:
                {
                        struct timeval50 *tv = addr;

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

#ifdef BIOCSORTIMEOUT
        /*
         * Set read timeout.
         */
        case BIOCSORTIMEOUT:
                {
                        struct timeval50 *tv = addr;

                        /* Compute number of ticks. */
                        d->bd_rtout = tv->tv_sec * hz + tv->tv_usec / tick;
                        if ((d->bd_rtout == 0) && (tv->tv_usec != 0))
                                d->bd_rtout = 1;
                        break;
                }
#endif

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

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

        case BIOCGSTATSOLD:
                {
                        struct bpf_stat_old *bs = 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 = addr;

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

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

        case BIOCSHDRCMPLT:     /* set "header already complete" flag */
                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 */
                /*
                 * No need to do anything special as we use IO_NDELAY in
                 * bpfread() as an indication of whether or not to block
                 * the read.
                 */
                break;

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

        case TIOCSPGRP:         /* Process or group to send signals to */
        case FIOSETOWN:
                error = fsetown(&d->bd_pgid, cmd, addr);
                break;

        case TIOCGPGRP:
        case FIOGETOWN:
                error = fgetown(d->bd_pgid, cmd, addr);
                break;
        }
        KERNEL_UNLOCK_ONE(NULL);
        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.
 */
int
bpf_setf(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 = splnet();
                d->bd_filter = 0;
                reset_d(d);
                splx(s);
                if (old != 0)
                        free(old, M_DEVBUF);
                return (0);
        }
        flen = fp->bf_len;
        if (flen > BPF_MAXINSNS)
                return (EINVAL);

        size = flen * sizeof(*fp->bf_insns);
        fcode = malloc(size, M_DEVBUF, M_WAITOK);
        if (copyin(fp->bf_insns, fcode, size) == 0 &&
            bpf_validate(fcode, (int)flen)) {
                s = splnet();
                d->bd_filter = fcode;
                reset_d(d);
                splx(s);
                if (old != 0)
                        free(old, M_DEVBUF);

                return (0);
        }
        free(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(struct bpf_d *d, struct ifreq *ifr)
{
        struct bpf_if *bp;
        char *cp;
        int unit_seen, i, s, error;

        /*
         * Make sure the provided name has a unit number, and default
         * it to '0' if not specified.
         * XXX This is ugly ... do this differently?
         */
        unit_seen = 0;
        cp = ifr->ifr_name;
        cp[sizeof(ifr->ifr_name) - 1] = '\0';   /* sanity */
        while (*cp++)
                if (*cp >= '0' && *cp <= '9')
                        unit_seen = 1;
        if (!unit_seen) {
                /* Make sure to leave room for the '\0'. */
                for (i = 0; i < (IFNAMSIZ - 1); ++i) {
                        if ((ifr->ifr_name[i] >= 'a' &&
                             ifr->ifr_name[i] <= 'z') ||
                            (ifr->ifr_name[i] >= 'A' &&
                             ifr->ifr_name[i] <= 'Z'))
                                continue;
                        ifr->ifr_name[i] = '0';
                }
        }

        /*
         * 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 ||
                    strcmp(ifp->if_xname, ifr->ifr_name) != 0)
                        continue;
                /* skip additional entry */
                if ((void **)bp->bif_driverp != &ifp->if_bpf)
                        continue;
                /*
                 * We found the requested interface.
                 * Allocate the packet buffers if we need to.
                 * If we're already attached to requested interface,
                 * just flush the buffer.
                 */
                if (d->bd_sbuf == 0) {
                        error = bpf_allocbufs(d);
                        if (error != 0)
                                return (error);
                }
                s = splnet();
                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);
}

/*
 * Copy the interface name to the ifreq.
 */
static void
bpf_ifname(struct ifnet *ifp, struct ifreq *ifr)
{
        memcpy(ifr->ifr_name, ifp->if_xname, IFNAMSIZ);
}

static int
bpf_stat(struct file *fp, struct stat *st)
{
        struct bpf_d *d = fp->f_data;

        (void)memset(st, 0, sizeof(*st));
        KERNEL_LOCK(1, NULL);
        st->st_dev = makedev(cdevsw_lookup_major(&bpf_cdevsw), d->bd_pid);
        st->st_atimespec = d->bd_atime;
        st->st_mtimespec = d->bd_mtime;
        st->st_ctimespec = st->st_birthtimespec = d->bd_btime;
        st->st_uid = kauth_cred_geteuid(fp->f_cred);
        st->st_gid = kauth_cred_getegid(fp->f_cred);
        KERNEL_UNLOCK_ONE(NULL);
        return 0;
}

/*
 * Support for poll() system call
 *
 * Return true iff the specific operation will not block indefinitely - with
 * the assumption that it is safe to positively acknowledge a request for the
 * ability to write to the BPF device.
 * Otherwise, return false but make a note that a selnotify() must be done.
 */
static int
bpf_poll(struct file *fp, int events)
{
        struct bpf_d *d = fp->f_data;
        int s = splnet();
        int revents;

        /*
         * Refresh the PID associated with this bpf file.
         */
        KERNEL_LOCK(1, NULL);
        d->bd_pid = curproc->p_pid;

        revents = events & (POLLOUT | POLLWRNORM);
        if (events & (POLLIN | POLLRDNORM)) {
                /*
                 * An imitation of the FIONREAD ioctl code.
                 */
                if (d->bd_hlen != 0 ||
                    ((d->bd_immediate || d->bd_state == BPF_TIMED_OUT) &&
                     d->bd_slen != 0)) {
                        revents |= events & (POLLIN | POLLRDNORM);
                } else {
                        selrecord(curlwp, &d->bd_sel);
                        /* Start the read timeout if necessary */
                        if (d->bd_rtout > 0 && d->bd_state == BPF_IDLE) {
                                callout_reset(&d->bd_callout, d->bd_rtout,
                                              bpf_timed_out, d);
                                d->bd_state = BPF_WAITING;
                        }
                }
        }

        KERNEL_UNLOCK_ONE(NULL);
        splx(s);
        return (revents);
}

static void
filt_bpfrdetach(struct knote *kn)
{
        struct bpf_d *d = kn->kn_hook;
        int s;

        KERNEL_LOCK(1, NULL);
        s = splnet();
        SLIST_REMOVE(&d->bd_sel.sel_klist, kn, knote, kn_selnext);
        splx(s);
        KERNEL_UNLOCK_ONE(NULL);
}

static int
filt_bpfread(struct knote *kn, long hint)
{
        struct bpf_d *d = kn->kn_hook;
        int rv;

        KERNEL_LOCK(1, NULL);
        kn->kn_data = d->bd_hlen;
        if (d->bd_immediate)
                kn->kn_data += d->bd_slen;
        rv = (kn->kn_data > 0);
        KERNEL_UNLOCK_ONE(NULL);
        return rv;
}

static const struct filterops bpfread_filtops =
        { 1, NULL, filt_bpfrdetach, filt_bpfread };

static int
bpf_kqfilter(struct file *fp, struct knote *kn)
{
        struct bpf_d *d = fp->f_data;
        struct klist *klist;
        int s;

        KERNEL_LOCK(1, NULL);

        switch (kn->kn_filter) {
        case EVFILT_READ:
                klist = &d->bd_sel.sel_klist;
                kn->kn_fop = &bpfread_filtops;
                break;

        default:
                KERNEL_UNLOCK_ONE(NULL);
                return (EINVAL);
        }

        kn->kn_hook = d;

        s = splnet();
        SLIST_INSERT_HEAD(klist, kn, kn_selnext);
        splx(s);
        KERNEL_UNLOCK_ONE(NULL);

        return (0);
}

/*
 * 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(void *arg, u_char *pkt, u_int pktlen)
{
        struct bpf_if *bp;
        struct bpf_d *d;
        u_int slen;
        struct timespec ts;
        int gottime=0;

        /*
         * 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 = arg;
        for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
                ++d->bd_rcount;
                ++bpf_gstats.bs_recv;
                slen = bpf_filter(d->bd_filter, pkt, pktlen, pktlen);
                if (slen != 0) {
                        if (!gottime) {
                                nanotime(&ts);
                                gottime = 1;
                        }
                        catchpacket(d, pkt, pktlen, slen, memcpy, &ts);
                }
        }
}

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

        m = src_arg;
        dst = dst_arg;
        while (len > 0) {
                if (m == NULL)
                        panic("bpf_mcpy");
                count = min(m->m_len, len);
                memcpy(dst, mtod(m, const void *), count);
                m = m->m_next;
                dst += count;
                len -= count;
        }
        return dst_arg;
}

/*
 * Dispatch a packet to all the listeners on interface bp.
 *
 * marg    pointer to the packet, either a data buffer or an mbuf chain
 * buflen  buffer length, if marg is a data buffer
 * cpfn    a function that can copy marg into the listener's buffer
 * pktlen  length of the packet
 * rcvif   either NULL or the interface the packet came in on.
 */
static inline void
bpf_deliver(struct bpf_if *bp, void *(*cpfn)(void *, const void *, size_t),
            void *marg, u_int pktlen, u_int buflen, struct ifnet *rcvif)
{
        u_int slen;
        struct bpf_d *d;
        struct timespec ts;
        int gottime = 0;

        for (d = bp->bif_dlist; d != 0; d = d->bd_next) {
                if (!d->bd_seesent && (rcvif == NULL))
                        continue;
                ++d->bd_rcount;
                ++bpf_gstats.bs_recv;
                slen = bpf_filter(d->bd_filter, marg, pktlen, buflen);
                if (slen != 0) {
                        if(!gottime) {
                                nanotime(&ts);
                                gottime = 1;
                        }
                        catchpacket(d, marg, pktlen, slen, cpfn, &ts);
                }
        }
}

/*
 * Incoming linkage from device drivers, when the head of the packet is in
 * a buffer, and the tail is in an mbuf chain.
 */
void
bpf_mtap2(void *arg, void *data, u_int dlen, struct mbuf *m)
{
        struct bpf_if *bp = arg;
        u_int pktlen;
        struct mbuf mb;

        pktlen = m_length(m) + dlen;

        /*
         * Craft on-stack mbuf suitable for passing to bpf_filter.
         * Note that we cut corners here; we only setup what's
         * absolutely needed--this mbuf should never go anywhere else.
         */
        (void)memset(&mb, 0, sizeof(mb));
        mb.m_next = m;
        mb.m_data = data;
        mb.m_len = dlen;

        bpf_deliver(bp, bpf_mcpy, &mb, pktlen, 0, m->m_pkthdr.rcvif);
}

/*
 * Incoming linkage from device drivers, when packet is in an mbuf chain.
 */
void
bpf_mtap(void *arg, struct mbuf *m)
{
        void *(*cpfn)(void *, const void *, size_t);
        struct bpf_if *bp = arg;
        u_int pktlen, buflen;
        void *marg;

        pktlen = m_length(m);

        if (pktlen == m->m_len) {
                cpfn = (void *)memcpy;
                marg = mtod(m, void *);
                buflen = pktlen;
        } else {
/*###1299 [cc] warning: assignment from incompatible pointer type%%%*/
                cpfn = bpf_mcpy;
                marg = m;
                buflen = 0;
        }

        bpf_deliver(bp, cpfn, marg, pktlen, buflen, m->m_pkthdr.rcvif);
}

/*
 * 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).
 */
void
bpf_mtap_af(void *arg, uint32_t af, struct mbuf *m)
{
        struct mbuf m0;

        m0.m_flags = 0;
        m0.m_next = m;
        m0.m_len = 4;
        m0.m_data = (char *)&af;

        bpf_mtap(arg, &m0);
}

void
bpf_mtap_et(void *arg, uint16_t et, struct mbuf *m)
{
        struct mbuf m0;

        m0.m_flags = 0;
        m0.m_next = m;
        m0.m_len = 14;
        m0.m_data = m0.m_dat;

        ((uint32_t *)m0.m_data)[0] = 0;
        ((uint32_t *)m0.m_data)[1] = 0;
        ((uint32_t *)m0.m_data)[2] = 0;
        ((uint16_t *)m0.m_data)[6] = et;

        bpf_mtap(arg, &m0);
}

#if NSL > 0 || NSTRIP > 0
/*
 * Put the SLIP pseudo-"link header" in place.
 * Note this M_PREPEND() should never fail,
 * swince we know we always have enough space
 * in the input buffer.
 */
void
bpf_mtap_sl_in(void *arg, u_char *chdr, struct mbuf **m)
{
        int s;
        u_char *hp;

        M_PREPEND(*m, SLIP_HDRLEN, M_DONTWAIT);
        if (*m == NULL)
                return;

        hp = mtod(*m, u_char *);
        hp[SLX_DIR] = SLIPDIR_IN;
        (void)memcpy(&hp[SLX_CHDR], chdr, CHDR_LEN);

        s = splnet();
        bpf_mtap(arg, *m);
        splx(s);

        m_adj(*m, SLIP_HDRLEN);
}

/*
 * Put the SLIP pseudo-"link header" in
 * place.  The compressed header is now
 * at the beginning of the mbuf.
 */
void
bpf_mtap_sl_out(void *arg, u_char *chdr, struct mbuf *m)
{
        struct mbuf m0;
        u_char *hp;
        int s;

        m0.m_flags = 0;
        m0.m_next = m;
        m0.m_data = m0.m_dat;
        m0.m_len = SLIP_HDRLEN;

        hp = mtod(&m0, u_char *);

        hp[SLX_DIR] = SLIPDIR_OUT;
        (void)memcpy(&hp[SLX_CHDR], chdr, CHDR_LEN);

        s = splnet();
        bpf_mtap(arg, &m0);
        splx(s);
        m_freem(m);
}
#endif

/*
 * 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.  memcpy is passed in to copy contiguous chunks, while
 * bpf_mcpy is passed in to copy mbuf chains.  In the latter case,
 * pkt is really an mbuf.
 */
static void
catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
    void *(*cpfn)(void *, const void *, size_t), struct timespec *ts)
{
        struct bpf_hdr *hp;
        int totlen, curlen;
        int hdrlen = d->bd_bif->bif_hdrlen;
        int do_wakeup = 0;

        ++d->bd_ccount;
        ++bpf_gstats.bs_capt;
        /*
         * 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;
                        ++bpf_gstats.bs_drop;
                        return;
                }
                ROTATE_BUFFERS(d);
                do_wakeup = 1;
                curlen = 0;
        } else if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT) {
                /*
                 * Immediate mode is set, or the read timeout has
                 * already expired during a select call.  A packet
                 * arrived, so the reader should be woken up.
                 */
                do_wakeup = 1;
        }

        /*
         * Append the bpf header.
         */
        hp = (struct bpf_hdr *)((char *)d->bd_sbuf + curlen);
        hp->bh_tstamp.tv_sec = ts->tv_sec;
        hp->bh_tstamp.tv_usec = ts->tv_nsec / 1000;
        hp->bh_datalen = pktlen;
        hp->bh_hdrlen = hdrlen;
        /*
         * Copy the packet data into the store buffer and update its length.
         */
        (*cpfn)((u_char *)hp + hdrlen, pkt, (hp->bh_caplen = totlen - hdrlen));
        d->bd_slen = curlen + totlen;

        /*
         * Call bpf_wakeup after bd_slen has been updated so that kevent(2)
         * will cause filt_bpfread() to be called with it adjusted.
         */
        if (do_wakeup)
                bpf_wakeup(d);
}

/*
 * Initialize all nonzero fields of a descriptor.
 */
static int
bpf_allocbufs(struct bpf_d *d)
{

        d->bd_fbuf = malloc(d->bd_bufsize, M_DEVBUF, M_NOWAIT);
        if (!d->bd_fbuf)
                return (ENOBUFS);
        d->bd_sbuf = malloc(d->bd_bufsize, M_DEVBUF, M_NOWAIT);
        if (!d->bd_sbuf) {
                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(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(d->bd_filter, M_DEVBUF);
}

/*
 * Attach an interface to bpf.  dlt is the link layer type; hdrlen is the
 * fixed size of the link header (variable length headers not yet supported).
 */
void
bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen)
{

        bpfattach2(ifp, dlt, hdrlen, &ifp->if_bpf);
}

/*
 * Attach additional dlt for a interface to bpf.  dlt is the link layer type;
 * hdrlen is the fixed size of the link header for the specified dlt
 * (variable length headers not yet supported).
 */
void
bpfattach2(struct ifnet *ifp, u_int dlt, u_int hdrlen, void *driverp)
{
        struct bpf_if *bp;
        bp = malloc(sizeof(*bp), M_DEVBUF, M_DONTWAIT);
        if (bp == 0)
                panic("bpfattach");

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

        bp->bif_next = bpf_iflist;
        bpf_iflist = bp;

        *bp->bif_driverp = 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;

#if 0
        printf("bpf: %s attached\n", ifp->if_xname);
#endif
}

/*
 * Remove an interface from bpf.
 */
void
bpfdetach(struct ifnet *ifp)
{
        struct bpf_if *bp, **pbp;
        struct bpf_d *d;
        int s;

        /* Nuke the vnodes for any open instances */
        LIST_FOREACH(d, &bpf_list, bd_list) {
                if (d->bd_bif != NULL && d->bd_bif->bif_ifp == ifp) {
                        /*
                         * Detach the descriptor from an interface now.
                         * It will be free'ed later by close routine.
                         */
                        s = splnet();
                        d->bd_promisc = 0;      /* we can't touch device. */
                        bpf_detachd(d);
                        splx(s);
                }
        }

  again:
        for (bp = bpf_iflist, pbp = &bpf_iflist;
             bp != NULL; pbp = &bp->bif_next, bp = bp->bif_next) {
                if (bp->bif_ifp == ifp) {
                        *pbp = bp->bif_next;
                        free(bp, M_DEVBUF);
                        goto again;
                }
        }
}

/*
 * Change the data link type of a interface.
 */
void
bpf_change_type(struct ifnet *ifp, u_int dlt, u_int hdrlen)
{
        struct bpf_if *bp;

        for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
                if ((void **)bp->bif_driverp == &ifp->if_bpf)
                        break;
        }
        if (bp == NULL)
                panic("bpf_change_type");

        bp->bif_dlt = dlt;

        /*
         * 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;
}

/*
 * Get a list of available data link type of the interface.
 */
static int
bpf_getdltlist(struct bpf_d *d, struct bpf_dltlist *bfl)
{
        int n, error;
        struct ifnet *ifp;
        struct bpf_if *bp;

        ifp = d->bd_bif->bif_ifp;
        n = 0;
        error = 0;
        for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
                if (bp->bif_ifp != ifp)
                        continue;
                if (bfl->bfl_list != NULL) {
                        if (n >= bfl->bfl_len)
                                return ENOMEM;
                        error = copyout(&bp->bif_dlt,
                            bfl->bfl_list + n, sizeof(u_int));
                }
                n++;
        }
        bfl->bfl_len = n;
        return error;
}

/*
 * Set the data link type of a BPF instance.
 */
static int
bpf_setdlt(struct bpf_d *d, u_int dlt)
{
        int s, error, opromisc;
        struct ifnet *ifp;
        struct bpf_if *bp;

        if (d->bd_bif->bif_dlt == dlt)
                return 0;
        ifp = d->bd_bif->bif_ifp;
        for (bp = bpf_iflist; bp != NULL; bp = bp->bif_next) {
                if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
                        break;
        }
        if (bp == NULL)
                return EINVAL;
        s = splnet();
        opromisc = d->bd_promisc;
        bpf_detachd(d);
        bpf_attachd(d, bp);
        reset_d(d);
        if (opromisc) {
                error = ifpromisc(bp->bif_ifp, 1);
                if (error)
                        printf("%s: bpf_setdlt: ifpromisc failed (%d)\n",
                            bp->bif_ifp->if_xname, error);
                else
                        d->bd_promisc = 1;
        }
        splx(s);
        return 0;
}

static int
sysctl_net_bpf_maxbufsize(SYSCTLFN_ARGS)
{
        int newsize, error;
        struct sysctlnode node;

        node = *rnode;
        node.sysctl_data = &newsize;
        newsize = bpf_maxbufsize;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return (error);

        if (newsize < BPF_MINBUFSIZE || newsize > BPF_MAXBUFSIZE)
                return (EINVAL);

        bpf_maxbufsize = newsize;

        return (0);
}

static int
sysctl_net_bpf_peers(SYSCTLFN_ARGS)
{
        int    error, elem_count;
        struct bpf_d     *dp;
        struct bpf_d_ext  dpe;
        size_t len, needed, elem_size, out_size;
        char   *sp;

        if (namelen == 1 && name[0] == CTL_QUERY)
                return (sysctl_query(SYSCTLFN_CALL(rnode)));

        if (namelen != 2)
                return (EINVAL);

        /* BPF peers is privileged information. */
        error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_INTERFACE,
            KAUTH_REQ_NETWORK_INTERFACE_GETPRIV, NULL, NULL, NULL);
        if (error)
                return (EPERM);

        len = (oldp != NULL) ? *oldlenp : 0;
        sp = oldp;
        elem_size = name[0];
        elem_count = name[1];
        out_size = MIN(sizeof(dpe), elem_size);
        needed = 0;

        if (elem_size < 1 || elem_count < 0)
                return (EINVAL);

        mutex_enter(&bpf_mtx);
        LIST_FOREACH(dp, &bpf_list, bd_list) {
                if (len >= elem_size && elem_count > 0) {
#define BPF_EXT(field)  dpe.bde_ ## field = dp->bd_ ## field
                        BPF_EXT(bufsize);
                        BPF_EXT(promisc);
                        BPF_EXT(promisc);
                        BPF_EXT(state);
                        BPF_EXT(immediate);
                        BPF_EXT(hdrcmplt);
                        BPF_EXT(seesent);
                        BPF_EXT(pid);
                        BPF_EXT(rcount);
                        BPF_EXT(dcount);
                        BPF_EXT(ccount);
#undef BPF_EXT
                        if (dp->bd_bif)
                                (void)strlcpy(dpe.bde_ifname,
                                    dp->bd_bif->bif_ifp->if_xname,
                                    IFNAMSIZ - 1);
                        else
                                dpe.bde_ifname[0] = '\0';

                        error = copyout(&dpe, sp, out_size);
                        if (error)
                                break;
                        sp += elem_size;
                        len -= elem_size;
                }
                needed += elem_size;
                if (elem_count > 0 && elem_count != INT_MAX)
                        elem_count--;
        }
        mutex_exit(&bpf_mtx);

        *oldlenp = needed;

        return (error);
}

SYSCTL_SETUP(sysctl_net_bpf_setup, "sysctl net.bpf subtree setup")
{
        const struct sysctlnode *node;

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "net", NULL,
                       NULL, 0, NULL, 0,
                       CTL_NET, CTL_EOL);

        node = NULL;
        sysctl_createv(clog, 0, NULL, &node,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "bpf",
                       SYSCTL_DESCR("BPF options"),
                       NULL, 0, NULL, 0,
                       CTL_NET, CTL_CREATE, CTL_EOL);
        if (node != NULL) {
                sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                        CTLTYPE_INT, "maxbufsize",
                        SYSCTL_DESCR("Maximum size for data capture buffer"),
                        sysctl_net_bpf_maxbufsize, 0, &bpf_maxbufsize, 0,
                        CTL_NET, node->sysctl_num, CTL_CREATE, CTL_EOL);
                sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_STRUCT, "stats",
                        SYSCTL_DESCR("BPF stats"),
                        NULL, 0, &bpf_gstats, sizeof(bpf_gstats),
                        CTL_NET, node->sysctl_num, CTL_CREATE, CTL_EOL);
                sysctl_createv(clog, 0, NULL, NULL,
                        CTLFLAG_PERMANENT,
                        CTLTYPE_STRUCT, "peers",
                        SYSCTL_DESCR("BPF peers"),
                        sysctl_net_bpf_peers, 0, NULL, 0,
                        CTL_NET, node->sysctl_num, CTL_CREATE, CTL_EOL);
        }

}