/*      $NetBSD: if_ppp.c,v 1.173 2024/07/05 04:31:53 rin Exp $ */
/*      Id: if_ppp.c,v 1.6 1997/03/04 03:33:00 paulus Exp       */

/*
 * if_ppp.c - Point-to-Point Protocol (PPP) Asynchronous driver.
 *
 * Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The name "Carnegie Mellon University" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For permission or any legal
 *    details, please contact
 *      Office of Technology Transfer
 *      Carnegie Mellon University
 *      5000 Forbes Avenue
 *      Pittsburgh, PA  15213-3890
 *      (412) 268-4387, fax: (412) 268-7395
 *      tech-transfer@andrew.cmu.edu
 *
 * 4. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Computing Services
 *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
 *
 * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Based on:
 *      @(#)if_sl.c     7.6.1.2 (Berkeley) 2/15/89
 *
 * Copyright (c) 1987 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Serial Line interface
 *
 * Rick Adams
 * Center for Seismic Studies
 * 1300 N 17th Street, Suite 1450
 * Arlington, Virginia 22209
 * (703)276-7900
 * rick@seismo.ARPA
 * seismo!rick
 *
 * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
 * Converted to 4.3BSD Beta by Chris Torek.
 * Other changes made at Berkeley, based in part on code by Kirk Smith.
 *
 * Converted to 4.3BSD+ 386BSD by Brad Parker (brad@cayman.com)
 * Added VJ tcp header compression; more unified ioctls
 *
 * Extensively modified by Paul Mackerras (paulus@cs.anu.edu.au).
 * Cleaned up a lot of the mbuf-related code to fix bugs that
 * caused system crashes and packet corruption.  Changed pppstart
 * so that it doesn't just give up with a collision if the whole
 * packet doesn't fit in the output ring buffer.
 *
 * Added priority queueing for interactive IP packets, following
 * the model of if_sl.c, plus hooks for bpf.
 * Paul Mackerras (paulus@cs.anu.edu.au).
 */

/* from if_sl.c,v 1.11 84/10/04 12:54:47 rick Exp */
/* from NetBSD: if_ppp.c,v 1.15.2.2 1994/07/28 05:17:58 cgd Exp */

/*
 * XXX IMP ME HARDER
 *
 * This is an explanation of that comment.  This code used to use
 * splimp() to block both network and tty interrupts.  However,
 * that call is deprecated.  So, we have replaced the uses of
 * splimp() with splhigh() in order to applomplish what it needs
 * to accomplish, and added that happy little comment.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_ppp.c,v 1.173 2024/07/05 04:31:53 rin Exp $");

#ifdef _KERNEL_OPT
#include "ppp.h"
#include "opt_inet.h"
#include "opt_gateway.h"
#include "opt_ppp.h"
#endif

#ifdef INET
#define VJC
#endif
#define PPP_COMPRESS

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/once.h>
#include <sys/conf.h>
#include <sys/kauth.h>
#include <sys/intr.h>
#include <sys/socketvar.h>
#include <sys/device.h>
#include <sys/module.h>

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

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#ifdef INET
#include <netinet/ip.h>
#endif

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

#ifdef VJC
#include <net/slcompress.h>
#endif

#include <net/ppp_defs.h>
#include <net/if_ppp.h>
#include <net/if_pppvar.h>
#include <sys/cpu.h>

#ifdef PPP_COMPRESS
#define PACKETPTR       struct mbuf *
#include <net/ppp-comp.h>
#endif

#include "ioconf.h"

static int      pppsioctl(struct ifnet *, u_long, void *);
static void     ppp_requeue(struct ppp_softc *);
static void     ppp_ccp(struct ppp_softc *, struct mbuf *m, int rcvd);
static void     ppp_ccp_closed(struct ppp_softc *);
static void     ppp_inproc(struct ppp_softc *, struct mbuf *);
static void     pppdumpm(struct mbuf *m0);
#ifdef ALTQ
static void     ppp_ifstart(struct ifnet *ifp);
#endif

static void     pppintr(void *);

extern struct linesw ppp_disc;

/*
 * We define two link layer specific mbuf flags, to mark high-priority
 * packets for output, and received packets following lost/corrupted
 * packets.
 */
#define M_HIGHPRI       M_LINK0 /* output packet for sc_fastq */
#define M_ERRMARK       M_LINK1 /* rx packet following lost/corrupted pkt */

static int ppp_clone_create(struct if_clone *, int);
static int ppp_clone_destroy(struct ifnet *);

static struct ppp_softc *ppp_create(const char *, int);

static struct {
        LIST_HEAD(ppp_sclist, ppp_softc) list;
        kmutex_t lock;
} ppp_softcs __cacheline_aligned;

struct if_clone ppp_cloner =
    IF_CLONE_INITIALIZER("ppp", ppp_clone_create, ppp_clone_destroy);

#ifdef PPP_COMPRESS
static LIST_HEAD(, compressor) ppp_compressors = { NULL };
static kmutex_t ppp_compressors_mtx;

static int ppp_compressor_init(void);
static int ppp_compressor_destroy(void);
static struct compressor *ppp_get_compressor(uint8_t);
static void ppp_compressor_rele(struct compressor *);
#endif /* PPP_COMPRESS */


/*
 * Called from boot code to establish ppp interfaces.
 */
void
pppattach(int n __unused)
{

        /*
         * Nothing to do here, initialization is handled by the
         * module initialization code in pppinit() below).
         */
}

static void
pppinit(void)
{
        /* Init the compressor sub-sub-system */
        ppp_compressor_init();

        if (ttyldisc_attach(&ppp_disc) != 0)
                panic("%s", __func__);

        mutex_init(&ppp_softcs.lock, MUTEX_DEFAULT, IPL_NONE);
        LIST_INIT(&ppp_softcs.list);
        if_clone_attach(&ppp_cloner);
}

static int
pppdetach(void)
{
        int error = 0;

        if (!LIST_EMPTY(&ppp_softcs.list))
                error = EBUSY;

        if (error == 0)
                error = ttyldisc_detach(&ppp_disc);

        if (error == 0) {
                mutex_destroy(&ppp_softcs.lock);
                if_clone_detach(&ppp_cloner);
                ppp_compressor_destroy();
        }

        return error;
}

static struct ppp_softc *
ppp_create(const char *name, int unit)
{
        struct ppp_softc *sc, *sci, *scl = NULL;

        sc = malloc(sizeof(*sc), M_DEVBUF, M_WAIT|M_ZERO);

        mutex_enter(&ppp_softcs.lock);
        if (unit == -1) {
                int i = 0;
                LIST_FOREACH(sci, &ppp_softcs.list, sc_iflist) {
                        scl = sci;
                        if (i < sci->sc_unit) {
                                unit = i;
                                break;
                        } else {
#ifdef DIAGNOSTIC
                                KASSERT(i == sci->sc_unit);
#endif
                                i++;
                        }
                }
                if (unit == -1)
                        unit = i;
        } else {
                LIST_FOREACH(sci, &ppp_softcs.list, sc_iflist) {
                        scl = sci;
                        if (unit < sci->sc_unit)
                                break;
                        else if (unit == sci->sc_unit) {
                                free(sc, M_DEVBUF);
                                mutex_exit(&ppp_softcs.lock);
                                return NULL;
                        }
                }
        }

        if (sci != NULL)
                LIST_INSERT_BEFORE(sci, sc, sc_iflist);
        else if (scl != NULL)
                LIST_INSERT_AFTER(scl, sc, sc_iflist);
        else
                LIST_INSERT_HEAD(&ppp_softcs.list, sc, sc_iflist);

        mutex_exit(&ppp_softcs.lock);

        if_initname(&sc->sc_if, name, sc->sc_unit = unit);
        callout_init(&sc->sc_timo_ch, 0);
        sc->sc_if.if_softc = sc;
        sc->sc_if.if_mtu = PPP_MTU;
        sc->sc_if.if_flags = IFF_POINTOPOINT | IFF_MULTICAST;
        sc->sc_if.if_type = IFT_PPP;
        sc->sc_if.if_hdrlen = PPP_HDRLEN;
        sc->sc_if.if_dlt = DLT_NULL;
        sc->sc_if.if_ioctl = pppsioctl;
        sc->sc_if.if_output = pppoutput;
#ifdef ALTQ
        sc->sc_if.if_start = ppp_ifstart;
#endif
        IFQ_SET_MAXLEN(&sc->sc_if.if_snd, IFQ_MAXLEN);
        IFQ_SET_MAXLEN(&sc->sc_inq, IFQ_MAXLEN);
        IFQ_SET_MAXLEN(&sc->sc_fastq, IFQ_MAXLEN);
        IFQ_SET_MAXLEN(&sc->sc_rawq, IFQ_MAXLEN);

        IFQ_LOCK_INIT(&sc->sc_fastq);

        /* Ratio of 1:2 packets between the regular and the fast queue */
        sc->sc_maxfastq = 2;
        IFQ_SET_READY(&sc->sc_if.if_snd);
        if_attach(&sc->sc_if);
        if_alloc_sadl(&sc->sc_if);
        bpf_attach(&sc->sc_if, DLT_NULL, 0);
        return sc;
}

static int
ppp_clone_create(struct if_clone *ifc, int unit)
{
        return ppp_create(ifc->ifc_name, unit) == NULL ? EEXIST : 0;
}

static int
ppp_clone_destroy(struct ifnet *ifp)
{
        struct ppp_softc *sc = (struct ppp_softc *)ifp->if_softc;

        if (sc->sc_devp != NULL)
                return EBUSY; /* Not removing it */

        mutex_enter(&ppp_softcs.lock);
        LIST_REMOVE(sc, sc_iflist);
        mutex_exit(&ppp_softcs.lock);

        bpf_detach(ifp);
        if_detach(ifp);

        IFQ_LOCK_DESTROY(&sc->sc_fastq);

        free(sc, M_DEVBUF);
        return 0;
}

/*
 * Allocate a ppp interface unit and initialize it.
 */
struct ppp_softc *
pppalloc(pid_t pid)
{
        struct ppp_softc *sc = NULL, *scf;
        int i;

        mutex_enter(&ppp_softcs.lock);
        LIST_FOREACH(scf, &ppp_softcs.list, sc_iflist) {
                if (scf->sc_xfer == pid) {
                        scf->sc_xfer = 0;
                        mutex_exit(&ppp_softcs.lock);
                        return scf;
                }
                if (scf->sc_devp == NULL && sc == NULL)
                        sc = scf;
        }
        mutex_exit(&ppp_softcs.lock);

        if (sc == NULL)
                sc = ppp_create(ppp_cloner.ifc_name, -1);

        sc->sc_si = softint_establish(SOFTINT_NET, pppintr, sc);
        if (sc->sc_si == NULL) {
                printf("%s: unable to establish softintr\n",
                    sc->sc_if.if_xname);
                return NULL;
        }
        sc->sc_flags = 0;
        sc->sc_mru = PPP_MRU;
        sc->sc_relinq = NULL;
        (void)memset(&sc->sc_stats, 0, sizeof(sc->sc_stats));
#ifdef VJC
        sc->sc_comp = malloc(sizeof(struct slcompress), M_DEVBUF, M_NOWAIT);
        if (sc->sc_comp)
                sl_compress_init(sc->sc_comp);
#endif
#ifdef PPP_COMPRESS
        sc->sc_xc_state = NULL;
        sc->sc_rc_state = NULL;
#endif /* PPP_COMPRESS */
        for (i = 0; i < NUM_NP; ++i)
                sc->sc_npmode[i] = NPMODE_ERROR;
        sc->sc_npqueue = NULL;
        sc->sc_npqtail = &sc->sc_npqueue;
        sc->sc_last_sent = sc->sc_last_recv = time_second;

        return sc;
}

/*
 * Deallocate a ppp unit.  Must be called at splsoftnet or higher.
 */
void
pppdealloc(struct ppp_softc *sc)
{
        struct mbuf *m;

        softint_disestablish(sc->sc_si);
        if_down(&sc->sc_if);
        sc->sc_if.if_flags &= ~(IFF_UP|IFF_RUNNING);
        sc->sc_devp = NULL;
        sc->sc_xfer = 0;
        for (;;) {
                IF_DEQUEUE(&sc->sc_rawq, m);
                if (m == NULL)
                        break;
                m_freem(m);
        }
        for (;;) {
                IF_DEQUEUE(&sc->sc_inq, m);
                if (m == NULL)
                        break;
                m_freem(m);
        }
        for (;;) {
                IF_DEQUEUE(&sc->sc_fastq, m);
                if (m == NULL)
                        break;
                m_freem(m);
        }
        while ((m = sc->sc_npqueue) != NULL) {
                sc->sc_npqueue = m->m_nextpkt;
                m_freem(m);
        }
        m_freem(sc->sc_togo);
        sc->sc_togo = NULL;
#ifdef PPP_COMPRESS
        ppp_ccp_closed(sc);
        sc->sc_xc_state = NULL;
        sc->sc_rc_state = NULL;
#endif /* PPP_COMPRESS */
#ifdef PPP_FILTER
        if (sc->sc_pass_filt_in.bf_insns != 0) {
                free(sc->sc_pass_filt_in.bf_insns, M_DEVBUF);
                sc->sc_pass_filt_in.bf_insns = 0;
                sc->sc_pass_filt_in.bf_len = 0;
        }
        if (sc->sc_pass_filt_out.bf_insns != 0) {
                free(sc->sc_pass_filt_out.bf_insns, M_DEVBUF);
                sc->sc_pass_filt_out.bf_insns = 0;
                sc->sc_pass_filt_out.bf_len = 0;
        }
        if (sc->sc_active_filt_in.bf_insns != 0) {
                free(sc->sc_active_filt_in.bf_insns, M_DEVBUF);
                sc->sc_active_filt_in.bf_insns = 0;
                sc->sc_active_filt_in.bf_len = 0;
        }
        if (sc->sc_active_filt_out.bf_insns != 0) {
                free(sc->sc_active_filt_out.bf_insns, M_DEVBUF);
                sc->sc_active_filt_out.bf_insns = 0;
                sc->sc_active_filt_out.bf_len = 0;
        }
#endif /* PPP_FILTER */
#ifdef VJC
        if (sc->sc_comp != 0) {
                free(sc->sc_comp, M_DEVBUF);
                sc->sc_comp = 0;
        }
#endif
        (void)ppp_clone_destroy(&sc->sc_if);
}

/*
 * Ioctl routine for generic ppp devices.
 */
int
pppioctl(struct ppp_softc *sc, u_long cmd, void *data, int flag,
    struct lwp *l)
{
        int s, error, flags, mru, npx;
        u_int nb;
        struct ppp_option_data *odp;
        struct compressor *cp;
        struct npioctl *npi;
        time_t t;
#ifdef PPP_FILTER
        struct bpf_program *bp, *nbp;
        struct bpf_insn *newcode, *oldcode;
        int newcodelen;
#endif /* PPP_FILTER */
#ifdef  PPP_COMPRESS
        u_char ccp_option[CCP_MAX_OPTION_LENGTH];
#endif

        switch (cmd) {
        case PPPIOCSFLAGS:
        case PPPIOCSMRU:
        case PPPIOCSMAXCID:
        case PPPIOCSCOMPRESS:
        case PPPIOCSNPMODE:
                if (kauth_authorize_network(l->l_cred, KAUTH_NETWORK_INTERFACE,
                        KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, &sc->sc_if,
                        KAUTH_ARG(cmd), NULL) != 0)
                        return EPERM;
                break;
        case PPPIOCXFERUNIT:
                /* XXX: Why is this privileged?! */
                if (kauth_authorize_network(l->l_cred, KAUTH_NETWORK_INTERFACE,
                        KAUTH_REQ_NETWORK_INTERFACE_GETPRIV, &sc->sc_if,
                        KAUTH_ARG(cmd), NULL) != 0)
                        return EPERM;
                break;
        default:
                break;
        }

        switch (cmd) {
        case FIONREAD:
                *(int *)data = sc->sc_inq.ifq_len;
                break;

        case PPPIOCGUNIT:
                *(int *)data = sc->sc_unit;
                break;

        case PPPIOCGFLAGS:
                *(u_int *)data = sc->sc_flags;
                break;

        case PPPIOCGRAWIN:
        {
                struct ppp_rawin *rwin = (struct ppp_rawin *)data;
                u_char c, q = 0;

                for (c = sc->sc_rawin_start; c < sizeof(sc->sc_rawin.buf);)
                        rwin->buf[q++] = sc->sc_rawin.buf[c++];

                for (c = 0; c < sc->sc_rawin_start;)
                        rwin->buf[q++] = sc->sc_rawin.buf[c++];

                rwin->count = sc->sc_rawin.count;
        }
        break;

        case PPPIOCSFLAGS:
                flags = *(int *)data & SC_MASK;
                s = splsoftnet();
#ifdef PPP_COMPRESS
                if (sc->sc_flags & SC_CCP_OPEN && !(flags & SC_CCP_OPEN))
                        ppp_ccp_closed(sc);
#endif
                splhigh();      /* XXX IMP ME HARDER */
                sc->sc_flags = (sc->sc_flags & ~SC_MASK) | flags;
                splx(s);
                break;

        case PPPIOCSMRU:
                mru = *(int *)data;
                if (mru >= PPP_MINMRU && mru <= PPP_MAXMRU)
                        sc->sc_mru = mru;
                break;

        case PPPIOCGMRU:
                *(int *)data = sc->sc_mru;
                break;

#ifdef VJC
        case PPPIOCSMAXCID:
                if (sc->sc_comp) {
                        s = splsoftnet();
                        sl_compress_setup(sc->sc_comp, *(int *)data);
                        splx(s);
                }
                break;
#endif

        case PPPIOCXFERUNIT:
                sc->sc_xfer = l->l_proc->p_pid;
                break;

#ifdef PPP_COMPRESS
        case PPPIOCSCOMPRESS:
                odp = (struct ppp_option_data *)data;
                nb = odp->length;
                if (nb > sizeof(ccp_option))
                        nb = sizeof(ccp_option);
                if (nb < 3)
                        return EINVAL;
                if ((error = copyin(odp->ptr, ccp_option, nb)) != 0)
                        return error;
                /* preliminary check on the length byte */
                if (ccp_option[1] < 2)
                        return EINVAL;
                cp = ppp_get_compressor(ccp_option[0]);
                if (cp == NULL) {
                        if (sc->sc_flags & SC_DEBUG)
                                printf("%s: no compressor for [%x %x %x], %x\n",
                                    sc->sc_if.if_xname, ccp_option[0],
                                    ccp_option[1], ccp_option[2], nb);
                        return EINVAL;  /* no handler found */
                }
                /*
                 * Found a handler for the protocol - try to allocate
                 * a compressor or decompressor.
                 */
                error = 0;
                if (odp->transmit) {
                        s = splsoftnet();
                        if (sc->sc_xc_state != NULL) {
                                (*sc->sc_xcomp->comp_free)(sc->sc_xc_state);
                                ppp_compressor_rele(sc->sc_xcomp);
                        }
                        sc->sc_xcomp = cp;
                        sc->sc_xc_state = cp->comp_alloc(ccp_option, nb);
                        if (sc->sc_xc_state == NULL) {
                                if (sc->sc_flags & SC_DEBUG)
                                        printf("%s: comp_alloc failed\n",
                                            sc->sc_if.if_xname);
                                error = ENOBUFS;
                        }
                        splhigh();      /* XXX IMP ME HARDER */
                        sc->sc_flags &= ~SC_COMP_RUN;
                        splx(s);
                } else {
                        s = splsoftnet();
                        if (sc->sc_rc_state != NULL) {
                                (*sc->sc_rcomp->decomp_free)(sc->sc_rc_state);
                                ppp_compressor_rele(sc->sc_rcomp);
                        }
                        sc->sc_rcomp = cp;
                        sc->sc_rc_state = cp->decomp_alloc(ccp_option, nb);
                        if (sc->sc_rc_state == NULL) {
                                if (sc->sc_flags & SC_DEBUG)
                                        printf("%s: decomp_alloc failed\n",
                                            sc->sc_if.if_xname);
                                error = ENOBUFS;
                        }
                        splhigh();      /* XXX IMP ME HARDER */
                        sc->sc_flags &= ~SC_DECOMP_RUN;
                        splx(s);
                }
                return error;
#endif /* PPP_COMPRESS */

        case PPPIOCGNPMODE:
        case PPPIOCSNPMODE:
                npi = (struct npioctl *)data;
                switch (npi->protocol) {
                case PPP_IP:
                        npx = NP_IP;
                        break;
                case PPP_IPV6:
                        npx = NP_IPV6;
                        break;
                default:
                        return EINVAL;
                }
                if (cmd == PPPIOCGNPMODE) {
                        npi->mode = sc->sc_npmode[npx];
                } else {
                        if (npi->mode != sc->sc_npmode[npx]) {
                                s = splnet();
                                sc->sc_npmode[npx] = npi->mode;
                                if (npi->mode != NPMODE_QUEUE) {
                                        ppp_requeue(sc);
                                        ppp_restart(sc);
                                }
                                splx(s);
                        }
                }
                break;

        case PPPIOCGIDLE:
                s = splsoftnet();
                t = time_second;
                ((struct ppp_idle *)data)->xmit_idle = t - sc->sc_last_sent;
                ((struct ppp_idle *)data)->recv_idle = t - sc->sc_last_recv;
                splx(s);
                break;

#ifdef PPP_FILTER
        case PPPIOCSPASS:
        case PPPIOCSACTIVE:
                /* These are no longer supported. */
                return EOPNOTSUPP;

        case PPPIOCSIPASS:
        case PPPIOCSOPASS:
        case PPPIOCSIACTIVE:
        case PPPIOCSOACTIVE:
                nbp = (struct bpf_program *)data;
                if ((unsigned) nbp->bf_len > BPF_MAXINSNS)
                        return EINVAL;
                newcodelen = nbp->bf_len * sizeof(struct bpf_insn);
                if (newcodelen != 0) {
                        newcode = malloc(newcodelen, M_DEVBUF, M_WAITOK);
                        /* WAITOK -- malloc() never fails. */
                        if ((error = copyin((void *)nbp->bf_insns,
                                    (void *)newcode, newcodelen)) != 0) {
                                free(newcode, M_DEVBUF);
                                return error;
                        }
                        if (!bpf_validate(newcode, nbp->bf_len)) {
                                free(newcode, M_DEVBUF);
                                return EINVAL;
                        }
                } else
                        newcode = 0;
                switch (cmd) {
                case PPPIOCSIPASS:
                        bp = &sc->sc_pass_filt_in;
                        break;

                case PPPIOCSOPASS:
                        bp = &sc->sc_pass_filt_out;
                        break;

                case PPPIOCSIACTIVE:
                        bp = &sc->sc_active_filt_in;
                        break;

                case PPPIOCSOACTIVE:
                        bp = &sc->sc_active_filt_out;
                        break;
                default:
                        free(newcode, M_DEVBUF);
                        return EPASSTHROUGH;
                }
                oldcode = bp->bf_insns;
                s = splnet();
                bp->bf_len = nbp->bf_len;
                bp->bf_insns = newcode;
                splx(s);
                if (oldcode != 0)
                        free(oldcode, M_DEVBUF);
                break;
#endif /* PPP_FILTER */

        default:
                return EPASSTHROUGH;
        }
        return 0;
}

/*
 * Process an ioctl request to the ppp network interface.
 */
static int
pppsioctl(struct ifnet *ifp, u_long cmd, void *data)
{
        struct ppp_softc *sc = ifp->if_softc;
        struct ifaddr *ifa = (struct ifaddr *)data;
        struct ifreq *ifr = (struct ifreq *)data;
        struct ppp_stats *psp;
#ifdef  PPP_COMPRESS
        struct ppp_comp_stats *pcp;
#endif
        int s = splnet(), error = 0;

        switch (cmd) {
        case SIOCSIFFLAGS:
                if ((error = ifioctl_common(ifp, cmd, data)) != 0)
                        break;
                if ((ifp->if_flags & IFF_RUNNING) == 0)
                        ifp->if_flags &= ~IFF_UP;
                break;

        case SIOCINITIFADDR:
                switch (ifa->ifa_addr->sa_family) {
#ifdef INET
                case AF_INET:
                        break;
#endif
#ifdef INET6
                case AF_INET6:
                        break;
#endif
                default:
                        printf("%s: af%d not supported\n", ifp->if_xname,
                            ifa->ifa_addr->sa_family);
                        error = EAFNOSUPPORT;
                        break;
                }
                ifa->ifa_rtrequest = p2p_rtrequest;
                break;

        case SIOCADDMULTI:
        case SIOCDELMULTI:
                if (ifr == NULL) {
                        error = EAFNOSUPPORT;
                        break;
                }
                switch (ifreq_getaddr(cmd, ifr)->sa_family) {
#ifdef INET
                case AF_INET:
                        break;
#endif
#ifdef INET6
                case AF_INET6:
                        break;
#endif
                default:
                        error = EAFNOSUPPORT;
                        break;
                }
                break;

        case SIOCGPPPSTATS:
                psp = &((struct ifpppstatsreq *)data)->stats;
                memset(psp, 0, sizeof(*psp));
                psp->p = sc->sc_stats;
#if defined(VJC) && !defined(SL_NO_STATS)
                if (sc->sc_comp) {
                        psp->vj.vjs_packets = sc->sc_comp->sls_packets;
                        psp->vj.vjs_compressed = sc->sc_comp->sls_compressed;
                        psp->vj.vjs_searches = sc->sc_comp->sls_searches;
                        psp->vj.vjs_misses = sc->sc_comp->sls_misses;
                        psp->vj.vjs_uncompressedin = sc->sc_comp->sls_uncompressedin;
                        psp->vj.vjs_compressedin = sc->sc_comp->sls_compressedin;
                        psp->vj.vjs_errorin = sc->sc_comp->sls_errorin;
                        psp->vj.vjs_tossed = sc->sc_comp->sls_tossed;
                }
#endif /* VJC */
                break;

#ifdef PPP_COMPRESS
        case SIOCGPPPCSTATS:
                pcp = &((struct ifpppcstatsreq *)data)->stats;
                memset(pcp, 0, sizeof(*pcp));
                if (sc->sc_xc_state != NULL)
                        (*sc->sc_xcomp->comp_stat)(sc->sc_xc_state, &pcp->c);
                if (sc->sc_rc_state != NULL)
                        (*sc->sc_rcomp->decomp_stat)(sc->sc_rc_state, &pcp->d);
                break;
#endif /* PPP_COMPRESS */

        default:
                if ((error = ifioctl_common(&sc->sc_if, cmd, data)) == ENETRESET)
                        error = 0;
                break;
        }
        splx(s);
        return error;
}

/*
 * Queue a packet.  Start transmission if not active.
 * Packet is placed in Information field of PPP frame.
 */
int
pppoutput(struct ifnet *ifp, struct mbuf *m0, const struct sockaddr *dst,
    const struct rtentry *rtp)
{
        struct ppp_softc *sc = ifp->if_softc;
        int protocol, address, control;
        u_char *cp;
        int s, error;
#ifdef INET
        struct ip *ip;
#endif
        struct ifqueue *ifq;
        enum NPmode mode;
        int len;

            if (sc->sc_devp == NULL ||
                (ifp->if_flags & IFF_RUNNING) == 0 ||
                ((ifp->if_flags & IFF_UP) == 0 &&
                    dst->sa_family != AF_UNSPEC)) {
                    error = ENETDOWN;   /* sort of */
                    goto bad;
            }

        IFQ_CLASSIFY(&ifp->if_snd, m0, dst->sa_family);

        /*
         * Compute PPP header.
         */
        m0->m_flags &= ~M_HIGHPRI;
        switch (dst->sa_family) {
#ifdef INET
        case AF_INET:
                address = PPP_ALLSTATIONS;
                control = PPP_UI;
                protocol = PPP_IP;
                mode = sc->sc_npmode[NP_IP];

                /*
                 * If this packet has the "low delay" bit set in the IP header,
                 * put it on the fastq instead.
                 */
                ip = mtod(m0, struct ip *);
                if (ip->ip_tos & IPTOS_LOWDELAY)
                        m0->m_flags |= M_HIGHPRI;
                break;
#endif
#ifdef INET6
        case AF_INET6:
                address = PPP_ALLSTATIONS;      /*XXX*/
                control = PPP_UI;               /*XXX*/
                protocol = PPP_IPV6;
                mode = sc->sc_npmode[NP_IPV6];

#if 0   /* XXX flowinfo/traffic class, maybe? */
        /*
         * If this packet has the "low delay" bit set in the IP header,
         * put it on the fastq instead.
         */
                ip = mtod(m0, struct ip *);
                if (ip->ip_tos & IPTOS_LOWDELAY)
                        m0->m_flags |= M_HIGHPRI;
#endif
                break;
#endif
        case AF_UNSPEC:
                address = PPP_ADDRESS(dst->sa_data);
                control = PPP_CONTROL(dst->sa_data);
                protocol = PPP_PROTOCOL(dst->sa_data);
                mode = NPMODE_PASS;
                break;
        default:
                printf("%s: af%d not supported\n", ifp->if_xname,
                    dst->sa_family);
                error = EAFNOSUPPORT;
                goto bad;
        }

        /*
         * Drop this packet, or return an error, if necessary.
         */
        if (mode == NPMODE_ERROR) {
                error = ENETDOWN;
                goto bad;
        }
        if (mode == NPMODE_DROP) {
                error = 0;
                goto bad;
        }

        /*
         * Add PPP header.
         */
        M_PREPEND(m0, PPP_HDRLEN, M_DONTWAIT);
        if (m0 == NULL) {
                error = ENOBUFS;
                goto bad;
        }

        cp = mtod(m0, u_char *);
        *cp++ = address;
        *cp++ = control;
        *cp++ = protocol >> 8;
        *cp++ = protocol & 0xff;

        len = m_length(m0);

        if (sc->sc_flags & SC_LOG_OUTPKT) {
                printf("%s output: ", ifp->if_xname);
                pppdumpm(m0);
        }

        if ((protocol & 0x8000) == 0) {
#ifdef PPP_FILTER
                /*
                 * Apply the pass and active filters to the packet,
                 * but only if it is a data packet.
                 */
                if (sc->sc_pass_filt_out.bf_insns != 0 &&
                    bpf_filter(sc->sc_pass_filt_out.bf_insns,
                        (u_char *)m0, len, 0) == 0) {
                        error = 0;              /* drop this packet */
                        goto bad;
                }

                /*
                 * Update the time we sent the most recent packet.
                 */
                if (sc->sc_active_filt_out.bf_insns == 0 ||
                    bpf_filter(sc->sc_active_filt_out.bf_insns,
                        (u_char *)m0, len, 0))
                        sc->sc_last_sent = time_second;
#else
                /*
                 * Update the time we sent the most recent packet.
                 */
                sc->sc_last_sent = time_second;
#endif /* PPP_FILTER */
        }

        /*
         * See if bpf wants to look at the packet.
         */
        bpf_mtap(&sc->sc_if, m0, BPF_D_OUT);

        /*
         * Put the packet on the appropriate queue.
         */
        s = splnet();
        if (mode == NPMODE_QUEUE) {
                /* XXX we should limit the number of packets on this queue */
                *sc->sc_npqtail = m0;
                m0->m_nextpkt = NULL;
                sc->sc_npqtail = &m0->m_nextpkt;
        } else {
                ifq = (m0->m_flags & M_HIGHPRI) ? &sc->sc_fastq : NULL;
                if ((error = ifq_enqueue2(&sc->sc_if, ifq, m0)) != 0) {
                        splx(s);
                        if_statinc(&sc->sc_if, if_oerrors);
                        sc->sc_stats.ppp_oerrors++;
                        return error;
                }
                ppp_restart(sc);
        }
        if_statadd2(ifp, if_opackets, 1, if_obytes, len);

        splx(s);
        return 0;

bad:
        m_freem(m0);
        return error;
}

/*
 * After a change in the NPmode for some NP, move packets from the
 * npqueue to the send queue or the fast queue as appropriate.
 * Should be called at splnet, since we muck with the queues.
 */
static void
ppp_requeue(struct ppp_softc *sc)
{
        struct mbuf *m, **mpp;
        struct ifqueue *ifq;
        enum NPmode mode;
        int error;

        for (mpp = &sc->sc_npqueue; (m = *mpp) != NULL; ) {
                switch (PPP_PROTOCOL(mtod(m, u_char *))) {
                case PPP_IP:
                        mode = sc->sc_npmode[NP_IP];
                        break;
                case PPP_IPV6:
                        mode = sc->sc_npmode[NP_IPV6];
                        break;
                default:
                        mode = NPMODE_PASS;
                }

                switch (mode) {
                case NPMODE_PASS:
                        /*
                         * This packet can now go on one of the queues to
                         * be sent.
                         */
                        *mpp = m->m_nextpkt;
                        m->m_nextpkt = NULL;
                        ifq = (m->m_flags & M_HIGHPRI) ? &sc->sc_fastq : NULL;
                        if ((error = ifq_enqueue2(&sc->sc_if, ifq, m)) != 0) {
                                if_statinc(&sc->sc_if, if_oerrors);
                                sc->sc_stats.ppp_oerrors++;
                        }
                        break;

                case NPMODE_DROP:
                case NPMODE_ERROR:
                        *mpp = m->m_nextpkt;
                        m_freem(m);
                        break;

                case NPMODE_QUEUE:
                        mpp = &m->m_nextpkt;
                        break;
                }
        }
        sc->sc_npqtail = mpp;
}

/*
 * Transmitter has finished outputting some stuff;
 * remember to call sc->sc_start later at splsoftnet.
 */
void
ppp_restart(struct ppp_softc *sc)
{
        int s = splhigh();      /* XXX IMP ME HARDER */

        sc->sc_flags &= ~SC_TBUSY;
        softint_schedule(sc->sc_si);
        splx(s);
}

/*
 * Get a packet to send.  This procedure is intended to be called at
 * splsoftnet, since it may involve time-consuming operations such as
 * applying VJ compression, packet compression, address/control and/or
 * protocol field compression to the packet.
 */
struct mbuf *
ppp_dequeue(struct ppp_softc *sc)
{
        struct mbuf *m, *mp;
        u_char *cp;
        int address, control, protocol;
        int s;

        /*
         * Grab a packet to send: first try the fast queue, then the
         * normal queue.
         */
        s = splnet();
        if (sc->sc_nfastq < sc->sc_maxfastq) {
                IF_DEQUEUE(&sc->sc_fastq, m);
                if (m != NULL)
                        sc->sc_nfastq++;
                else
                        IFQ_DEQUEUE(&sc->sc_if.if_snd, m);
        } else {
                sc->sc_nfastq = 0;
                IFQ_DEQUEUE(&sc->sc_if.if_snd, m);
                if (m == NULL) {
                        IF_DEQUEUE(&sc->sc_fastq, m);
                        if (m != NULL)
                                sc->sc_nfastq++;
                }
        }
        splx(s);

        if (m == NULL)
                return NULL;

        ++sc->sc_stats.ppp_opackets;

        /*
         * Extract the ppp header of the new packet.
         * The ppp header will be in one mbuf.
         */
        cp = mtod(m, u_char *);
        address = PPP_ADDRESS(cp);
        control = PPP_CONTROL(cp);
        protocol = PPP_PROTOCOL(cp);

        switch (protocol) {
        case PPP_IP:
#ifdef VJC
                /*
                 * If the packet is a TCP/IP packet, see if we can compress it.
                 */
                if ((sc->sc_flags & SC_COMP_TCP) && sc->sc_comp != NULL) {
                        struct ip *ip;
                        int type;

                        mp = m;
                        ip = (struct ip *)(cp + PPP_HDRLEN);
                        if (mp->m_len <= PPP_HDRLEN) {
                                mp = mp->m_next;
                                if (mp == NULL)
                                        break;
                                ip = mtod(mp, struct ip *);
                        }
                        /*
                         * This code assumes the IP/TCP header is in one
                         * non-shared mbuf
                         */
                        if (ip->ip_p == IPPROTO_TCP) {
                                type = sl_compress_tcp(mp, ip, sc->sc_comp,
                                    !(sc->sc_flags & SC_NO_TCP_CCID));
                                switch (type) {
                                case TYPE_UNCOMPRESSED_TCP:
                                        protocol = PPP_VJC_UNCOMP;
                                        break;
                                case TYPE_COMPRESSED_TCP:
                                        protocol = PPP_VJC_COMP;
                                        cp = mtod(m, u_char *);
                                        cp[0] = address; /* Header has moved */
                                        cp[1] = control;
                                        cp[2] = 0;
                                        break;
                                }
                                /* Update protocol in PPP header */
                                cp[3] = protocol;
                        }
                }
#endif  /* VJC */
                break;

#ifdef PPP_COMPRESS
        case PPP_CCP:
                ppp_ccp(sc, m, 0);
                break;
#endif  /* PPP_COMPRESS */
        }

#ifdef PPP_COMPRESS
        if (protocol != PPP_LCP && protocol != PPP_CCP &&
            sc->sc_xc_state && (sc->sc_flags & SC_COMP_RUN)) {
                struct mbuf *mcomp = NULL;
                int slen;

                slen = 0;
                for (mp = m; mp != NULL; mp = mp->m_next)
                        slen += mp->m_len;
                (*sc->sc_xcomp->compress)
                    (sc->sc_xc_state, &mcomp, m, slen, sc->sc_if.if_mtu + PPP_HDRLEN);
                if (mcomp != NULL) {
                        if (sc->sc_flags & SC_CCP_UP) {
                                /*
                                 * Send the compressed packet instead of the
                                 * original.
                                 */
                                m_freem(m);
                                m = mcomp;
                                cp = mtod(m, u_char *);
                                protocol = cp[3];
                        } else {
                                /*
                                 * Can't transmit compressed packets until CCP
                                 * is up.
                                 */
                                m_freem(mcomp);
                        }
                }
        }
#endif  /* PPP_COMPRESS */

        /*
         * Compress the address/control and protocol, if possible.
         */
        if (sc->sc_flags & SC_COMP_AC && address == PPP_ALLSTATIONS &&
            control == PPP_UI && protocol != PPP_ALLSTATIONS &&
            protocol != PPP_LCP) {
                /* can compress address/control */
                m->m_data += 2;
                m->m_len -= 2;
        }
        if (sc->sc_flags & SC_COMP_PROT && protocol < 0xFF) {
                /* can compress protocol */
                if (mtod(m, u_char *) == cp) {
                        cp[2] = cp[1];  /* move address/control up */
                        cp[1] = cp[0];
                }
                ++m->m_data;
                --m->m_len;
        }

        return m;
}

/*
 * Software interrupt routine, called at splsoftnet.
 */
static void
pppintr(void *arg)
{
        struct ppp_softc *sc = arg;
        struct mbuf *m;
        int s;

        mutex_enter(softnet_lock);
        if (!(sc->sc_flags & SC_TBUSY) &&
            (IFQ_IS_EMPTY(&sc->sc_if.if_snd) == 0 ||
                sc->sc_fastq.ifq_head ||
                sc->sc_outm)) {
                s = splhigh();  /* XXX IMP ME HARDER */
                sc->sc_flags |= SC_TBUSY;
                splx(s);
                (*sc->sc_start)(sc);
        }
        for (;;) {
                s = splnet();
                IF_DEQUEUE(&sc->sc_rawq, m);
                splx(s);
                if (m == NULL)
                        break;
                ppp_inproc(sc, m);
        }
        mutex_exit(softnet_lock);
}

#ifdef PPP_COMPRESS
/*
 * Handle a CCP packet.  `rcvd' is 1 if the packet was received,
 * 0 if it is about to be transmitted.
 */
static void
ppp_ccp(struct ppp_softc *sc, struct mbuf *m, int rcvd)
{
        u_char *dp, *ep;
        struct mbuf *mp;
        int slen, s;

        /*
         * Get a pointer to the data after the PPP header.
         */
        if (m->m_len <= PPP_HDRLEN) {
                mp = m->m_next;
                if (mp == NULL)
                        return;
                dp = mtod(mp, u_char *);
        } else {
                mp = m;
                dp = mtod(mp, u_char *) + PPP_HDRLEN;
        }

        ep = mtod(mp, u_char *) + mp->m_len;
        if (dp + CCP_HDRLEN > ep)
                return;
        slen = CCP_LENGTH(dp);
        if (dp + slen > ep) {
                if (sc->sc_flags & SC_DEBUG)
                        printf("if_ppp/ccp: not enough data in mbuf (%p+%x > %p+%x)\n",
                            dp, slen, mtod(mp, u_char *), mp->m_len);
                return;
        }

        switch (CCP_CODE(dp)) {
        case CCP_CONFREQ:
        case CCP_TERMREQ:
        case CCP_TERMACK:
                /* CCP must be going down - disable compression */
                if (sc->sc_flags & SC_CCP_UP) {
                        s = splhigh();  /* XXX IMP ME HARDER */
                        sc->sc_flags &= ~(SC_CCP_UP | SC_COMP_RUN | SC_DECOMP_RUN);
                        splx(s);
                }
                break;

        case CCP_CONFACK:
                if (sc->sc_flags & SC_CCP_OPEN &&
                    !(sc->sc_flags & SC_CCP_UP) &&
                    slen >= CCP_HDRLEN + CCP_OPT_MINLEN &&
                    slen >= CCP_OPT_LENGTH(dp + CCP_HDRLEN) + CCP_HDRLEN) {
                        if (!rcvd) {
                                /* We're agreeing to send compressed packets. */
                                if (sc->sc_xc_state != NULL &&
                                    (*sc->sc_xcomp->comp_init)(sc->sc_xc_state,
                                        dp + CCP_HDRLEN, slen - CCP_HDRLEN,
                                        sc->sc_unit, 0,
                                        sc->sc_flags & SC_DEBUG)) {
                                        s = splhigh();  /* XXX IMP ME HARDER */
                                        sc->sc_flags |= SC_COMP_RUN;
                                        splx(s);
                                }
                        } else {
                                /*
                                 * Peer is agreeing to send compressed
                                 * packets.
                                 */
                                if (sc->sc_rc_state != NULL &&
                                    (*sc->sc_rcomp->decomp_init)(
                                        sc->sc_rc_state,
                                        dp + CCP_HDRLEN, slen - CCP_HDRLEN,
                                        sc->sc_unit, 0, sc->sc_mru,
                                        sc->sc_flags & SC_DEBUG)) {
                                        s = splhigh();  /* XXX IMP ME HARDER */
                                        sc->sc_flags |= SC_DECOMP_RUN;
                                        sc->sc_flags &=
                                            ~(SC_DC_ERROR | SC_DC_FERROR);
                                        splx(s);
                                }
                        }
                }
                break;

        case CCP_RESETACK:
                if (sc->sc_flags & SC_CCP_UP) {
                        if (!rcvd) {
                                if (sc->sc_xc_state && (sc->sc_flags & SC_COMP_RUN))
                                        (*sc->sc_xcomp->comp_reset)(sc->sc_xc_state);
                        } else {
                                if (sc->sc_rc_state && (sc->sc_flags & SC_DECOMP_RUN)) {
                                        (*sc->sc_rcomp->decomp_reset)(sc->sc_rc_state);
                                        s = splhigh();  /* XXX IMP ME HARDER */
                                        sc->sc_flags &= ~SC_DC_ERROR;
                                        splx(s);
                                }
                        }
                }
                break;
        }
}

/*
 * CCP is down; free (de)compressor state if necessary.
 */
static void
ppp_ccp_closed(struct ppp_softc *sc)
{
        if (sc->sc_xc_state) {
                (*sc->sc_xcomp->comp_free)(sc->sc_xc_state);
                ppp_compressor_rele(sc->sc_xcomp);
                sc->sc_xc_state = NULL;
        }
        if (sc->sc_rc_state) {
                (*sc->sc_rcomp->decomp_free)(sc->sc_rc_state);
                ppp_compressor_rele(sc->sc_rcomp);
                sc->sc_rc_state = NULL;
        }
}
#endif /* PPP_COMPRESS */

/*
 * PPP packet input routine.
 * The caller has checked and removed the FCS and has inserted
 * the address/control bytes and the protocol high byte if they
 * were omitted.
 */
void
ppppktin(struct ppp_softc *sc, struct mbuf *m, int lost)
{
        int s = splhigh();      /* XXX IMP ME HARDER */

        if (lost)
                m->m_flags |= M_ERRMARK;
        IF_ENQUEUE(&sc->sc_rawq, m);
        softint_schedule(sc->sc_si);
        splx(s);
}

/*
 * Process a received PPP packet, doing decompression as necessary.
 * Should be called at splsoftnet.
 */
#define COMPTYPE(proto)                                                       \
        ((proto) == PPP_VJC_COMP ? TYPE_COMPRESSED_TCP                        \
            : TYPE_UNCOMPRESSED_TCP)

static void
ppp_inproc(struct ppp_softc *sc, struct mbuf *m)
{
        struct ifnet *ifp = &sc->sc_if;
        pktqueue_t *pktq = NULL;
        struct ifqueue *inq = NULL;
        int s, ilen, proto, rv;
        u_char *cp, adrs, ctrl;
        struct mbuf *mp, *dmp = NULL;
#ifdef VJC
        int xlen;
        u_char *iphdr;
        u_int hlen;
#endif

        sc->sc_stats.ppp_ipackets++;

        if (sc->sc_flags & SC_LOG_INPKT) {
                ilen = 0;
                for (mp = m; mp != NULL; mp = mp->m_next)
                        ilen += mp->m_len;
                printf("%s: got %d bytes\n", ifp->if_xname, ilen);
                pppdumpm(m);
        }

        cp = mtod(m, u_char *);
        adrs = PPP_ADDRESS(cp);
        ctrl = PPP_CONTROL(cp);
        proto = PPP_PROTOCOL(cp);

        if (m->m_flags & M_ERRMARK) {
                m->m_flags &= ~M_ERRMARK;
                s = splhigh();  /* XXX IMP ME HARDER */
                sc->sc_flags |= SC_VJ_RESET;
                splx(s);
        }

#ifdef PPP_COMPRESS
        /*
         * Decompress this packet if necessary, update the receiver's
         * dictionary, or take appropriate action on a CCP packet.
         */
        if (proto == PPP_COMP &&
            sc->sc_rc_state &&
            (sc->sc_flags & SC_DECOMP_RUN) &&
            !(sc->sc_flags & SC_DC_ERROR) &&
            !(sc->sc_flags & SC_DC_FERROR)) {
                /* Decompress this packet */
                rv = (*sc->sc_rcomp->decompress)(sc->sc_rc_state, m, &dmp);
                if (rv == DECOMP_OK) {
                        m_freem(m);
                        if (dmp == NULL) {
                                /*
                                 * No error, but no decompressed packet
                                 * produced
                                 */
                                return;
                        }
                        m = dmp;
                        cp = mtod(m, u_char *);
                        proto = PPP_PROTOCOL(cp);

                } else {
                        /*
                         * An error has occurred in decompression.
                         * Pass the compressed packet up to pppd, which may
                         * take CCP down or issue a Reset-Req.
                         */
                        if (sc->sc_flags & SC_DEBUG)
                                printf("%s: decompress failed %d\n",
                                    ifp->if_xname, rv);
                        s = splhigh();  /* XXX IMP ME HARDER */
                        sc->sc_flags |= SC_VJ_RESET;
                        if (rv == DECOMP_ERROR)
                                sc->sc_flags |= SC_DC_ERROR;
                        else
                                sc->sc_flags |= SC_DC_FERROR;
                        splx(s);
                }

        } else {
                if (sc->sc_rc_state && (sc->sc_flags & SC_DECOMP_RUN))
                        (*sc->sc_rcomp->incomp)(sc->sc_rc_state, m);
                if (proto == PPP_CCP)
                        ppp_ccp(sc, m, 1);
        }
#endif

        ilen = 0;
        for (mp = m; mp != NULL; mp = mp->m_next)
                ilen += mp->m_len;

#ifdef VJC
        if (sc->sc_flags & SC_VJ_RESET) {
                /*
                 * If we've missed a packet, we must toss subsequent compressed
                 * packets which don't have an explicit connection ID.
                 */
                if (sc->sc_comp)
                        sl_uncompress_tcp(NULL, 0, TYPE_ERROR, sc->sc_comp);
                s = splhigh();  /* XXX IMP ME HARDER */
                sc->sc_flags &= ~SC_VJ_RESET;
                splx(s);
        }

        /*
         * See if we have a VJ-compressed packet to uncompress.
         */
        if (proto == PPP_VJC_COMP) {
                if ((sc->sc_flags & SC_REJ_COMP_TCP) || sc->sc_comp == 0)
                        goto bad;

                xlen = sl_uncompress_tcp_core(cp + PPP_HDRLEN,
                    m->m_len - PPP_HDRLEN, ilen - PPP_HDRLEN,
                    TYPE_COMPRESSED_TCP, sc->sc_comp, &iphdr, &hlen);
                if (xlen <= 0) {
                        if (sc->sc_flags & SC_DEBUG) {
                                printf("%s: VJ uncompress failed"
                                    " on type comp\n",
                                    ifp->if_xname);
                        }
                        goto bad;
                }

                /* Copy the PPP and IP headers into a new mbuf. */
                MGETHDR(mp, M_DONTWAIT, MT_DATA);
                if (mp == NULL)
                        goto bad;
                mp->m_len = 0;
                mp->m_next = NULL;
                if (hlen + PPP_HDRLEN > MHLEN) {
                        MCLGET(mp, M_DONTWAIT);
                        if (M_TRAILINGSPACE(mp) < hlen + PPP_HDRLEN) {
                                /* Lose if big headers and no clusters */
                                m_freem(mp);
                                goto bad;
                        }
                }
                cp = mtod(mp, u_char *);
                cp[0] = adrs;
                cp[1] = ctrl;
                cp[2] = 0;
                cp[3] = PPP_IP;
                proto = PPP_IP;
                bcopy(iphdr, cp + PPP_HDRLEN, hlen);
                mp->m_len = hlen + PPP_HDRLEN;

                /*
                 * Trim the PPP and VJ headers off the old mbuf
                 * and stick the new and old mbufs together.
                 */
                m->m_data += PPP_HDRLEN + xlen;
                m->m_len -= PPP_HDRLEN + xlen;
                if (m->m_len <= M_TRAILINGSPACE(mp)) {
                        bcopy(mtod(m, u_char *),
                            mtod(mp, u_char *) + mp->m_len, m->m_len);
                        mp->m_len += m->m_len;
                        mp->m_next = m_free(m);
                } else
                        mp->m_next = m;
                m = mp;
                ilen += hlen - xlen;

        } else if (proto == PPP_VJC_UNCOMP) {
                if ((sc->sc_flags & SC_REJ_COMP_TCP) || sc->sc_comp == 0)
                        goto bad;

                xlen = sl_uncompress_tcp_core(cp + PPP_HDRLEN,
                    m->m_len - PPP_HDRLEN, ilen - PPP_HDRLEN,
                    TYPE_UNCOMPRESSED_TCP, sc->sc_comp, &iphdr, &hlen);
                if (xlen < 0) {
                        if (sc->sc_flags & SC_DEBUG) {
                                printf("%s: VJ uncompress failed"
                                    " on type uncomp\n",
                                    ifp->if_xname);
                        }
                        goto bad;
                }

                proto = PPP_IP;
                cp[3] = PPP_IP;
        }
#endif /* VJC */

        /*
         * If the packet will fit in a header mbuf, don't waste a
         * whole cluster on it.
         */
        if (ilen <= MHLEN && (m->m_flags & M_EXT)) {
                MGETHDR(mp, M_DONTWAIT, MT_DATA);
                if (mp != NULL) {
                        m_copydata(m, 0, ilen, mtod(mp, void *));
                        m_freem(m);
                        m = mp;
                        m->m_len = ilen;
                }
        }
        m->m_pkthdr.len = ilen;
        m_set_rcvif(m, ifp);

        if ((proto & 0x8000) == 0) {
#ifdef PPP_FILTER
                /*
                 * See whether we want to pass this packet, and
                 * if it counts as link activity.
                 */
                if (sc->sc_pass_filt_in.bf_insns != 0 &&
                    bpf_filter(sc->sc_pass_filt_in.bf_insns,
                        (u_char *)m, ilen, 0) == 0) {
                        /* drop this packet */
                        m_freem(m);
                        return;
                }
                if (sc->sc_active_filt_in.bf_insns == 0 ||
                    bpf_filter(sc->sc_active_filt_in.bf_insns,
                        (u_char *)m, ilen, 0))
                        sc->sc_last_recv = time_second;
#else
                /*
                 * Record the time that we received this packet.
                 */
                sc->sc_last_recv = time_second;
#endif /* PPP_FILTER */
        }

        /* See if bpf wants to look at the packet. */
        bpf_mtap(&sc->sc_if, m, BPF_D_IN);

        switch (proto) {
#ifdef INET
        case PPP_IP:
                /*
                 * IP packet - take off the ppp header and pass it up to IP.
                 */
                if ((ifp->if_flags & IFF_UP) == 0 ||
                    sc->sc_npmode[NP_IP] != NPMODE_PASS) {
                        /* Interface is down - drop the packet. */
                        m_freem(m);
                        return;
                }
                m->m_pkthdr.len -= PPP_HDRLEN;
                m->m_data += PPP_HDRLEN;
                m->m_len -= PPP_HDRLEN;
#ifdef GATEWAY
                if (ipflow_fastforward(m))
                        return;
#endif
                pktq = ip_pktq;
                break;
#endif

#ifdef INET6
        case PPP_IPV6:
                /*
                 * IPv6 packet - take off the ppp header and pass it up to
                 * IPv6.
                 */
                if ((ifp->if_flags & IFF_UP) == 0 ||
                    sc->sc_npmode[NP_IPV6] != NPMODE_PASS) {
                        /* interface is down - drop the packet. */
                        m_freem(m);
                        return;
                }
                m->m_pkthdr.len -= PPP_HDRLEN;
                m->m_data += PPP_HDRLEN;
                m->m_len -= PPP_HDRLEN;
#ifdef GATEWAY
                if (ip6flow_fastforward(&m))
                        return;
#endif
                pktq = ip6_pktq;
                break;
#endif

        default:
                /*
                 * Some other protocol - place on input queue for read().
                 */
                inq = &sc->sc_inq;
                pktq = NULL;
                break;
        }

        /*
         * Put the packet on the appropriate input queue.
         */
        s = splnet();

        /* pktq: inet or inet6 cases */
        if (__predict_true(pktq)) {
                if (__predict_false(!pktq_enqueue(pktq, m, 0))) {
                        splx(s);
                        if_statinc(ifp, if_iqdrops);
                        goto bad;
                }
                if_statadd2(ifp, if_ipackets, 1, if_ibytes, ilen);
                splx(s);
                return;
        }

        /* ifq: other protocol cases */
        if (!inq) {
                splx(s);
                goto bad;
        }
        if (IF_QFULL(inq)) {
                IF_DROP(inq);
                splx(s);
                if (sc->sc_flags & SC_DEBUG)
                        printf("%s: input queue full\n", ifp->if_xname);
                if_statinc(ifp, if_iqdrops);
                goto bad;
        }
        IF_ENQUEUE(inq, m);
        splx(s);
        if_statadd2(ifp, if_ipackets, 1, if_ibytes, ilen);

        (*sc->sc_ctlp)(sc);

        return;

bad:
        m_freem(m);
        if_statinc(&sc->sc_if, if_ierrors);
        sc->sc_stats.ppp_ierrors++;
}

#define MAX_DUMP_BYTES  128

static void
pppdumpm(struct mbuf *m0)
{
        char buf[3*MAX_DUMP_BYTES+4];
        char *bp = buf;
        struct mbuf *m;

        for (m = m0; m; m = m->m_next) {
                int l = m->m_len;
                u_char *rptr = (u_char *)m->m_data;

                while (l--) {
                        if (bp > buf + sizeof(buf) - 4)
                                goto done;
                        /* Convert byte to ascii hex */
                        *bp++ = hexdigits[*rptr >> 4];
                        *bp++ = hexdigits[*rptr++ & 0xf];
                }

                if (m->m_next) {
                        if (bp > buf + sizeof(buf) - 3)
                                goto done;
                        *bp++ = '|';
                } else
                        *bp++ = ' ';
        }
done:
        if (m)
                *bp++ = '>';
        *bp = 0;
        printf("%s\n", buf);
}

#ifdef ALTQ
/*
 * A wrapper to transmit a packet from if_start since ALTQ uses
 * if_start to send a packet.
 */
static void
ppp_ifstart(struct ifnet *ifp)
{
        struct ppp_softc *sc;

        sc = ifp->if_softc;
        (*sc->sc_start)(sc);
}
#endif

static const struct ppp_known_compressor {
        uint8_t code;
        const char *module;
} ppp_known_compressors[] = {
        { CI_DEFLATE, "ppp_deflate" },
        { CI_DEFLATE_DRAFT, "ppp_deflate" },
        { CI_BSD_COMPRESS, "ppp_bsdcomp" },
        { CI_MPPE, "ppp_mppe" },
        { 0, NULL }
};

static int
ppp_compressor_init(void)
{

        mutex_init(&ppp_compressors_mtx, MUTEX_DEFAULT, IPL_NONE);
        return 0;
}

static int
ppp_compressor_destroy(void)
{

        mutex_destroy(&ppp_compressors_mtx);
        return 0;
}

static void
ppp_compressor_rele(struct compressor *cp)
{

        mutex_enter(&ppp_compressors_mtx);
        --cp->comp_refcnt;
        mutex_exit(&ppp_compressors_mtx);
}

static struct compressor *
ppp_get_compressor_noload(uint8_t ci, bool hold)
{
        struct compressor *cp;

        KASSERT(mutex_owned(&ppp_compressors_mtx));
        LIST_FOREACH(cp, &ppp_compressors, comp_list) {
                if (cp->compress_proto == ci) {
                        if (hold)
                                ++cp->comp_refcnt;
                        return cp;
                }
        }

        return NULL;
}

static struct compressor *
ppp_get_compressor(uint8_t ci)
{
        struct compressor *cp = NULL;
        const struct ppp_known_compressor *pkc;

        mutex_enter(&ppp_compressors_mtx);
        cp = ppp_get_compressor_noload(ci, true);
        mutex_exit(&ppp_compressors_mtx);
        if (cp != NULL)
                return cp;

        kernconfig_lock();
        mutex_enter(&ppp_compressors_mtx);
        cp = ppp_get_compressor_noload(ci, true);
        mutex_exit(&ppp_compressors_mtx);
        if (cp == NULL) {
                /* Not found, so try to autoload a module */
                for (pkc = ppp_known_compressors; pkc->module != NULL; pkc++) {
                        if (pkc->code == ci) {
                                if (module_autoload(pkc->module,
                                        MODULE_CLASS_MISC) != 0)
                                        break;
                                mutex_enter(&ppp_compressors_mtx);
                                cp = ppp_get_compressor_noload(ci, true);
                                mutex_exit(&ppp_compressors_mtx);
                                break;
                        }
                }
        }
        kernconfig_unlock();

        return cp;
}

int
ppp_register_compressor(struct compressor *pc, size_t ncomp)
{
        int error = 0;
        size_t i;

        mutex_enter(&ppp_compressors_mtx);
        for (i = 0; i < ncomp; i++) {
                if (ppp_get_compressor_noload(pc[i].compress_proto,
                        false) != NULL)
                        error = EEXIST;
        }
        if (!error) {
                for (i = 0; i < ncomp; i++) {
                        pc[i].comp_refcnt = 0;
                        LIST_INSERT_HEAD(&ppp_compressors, &pc[i], comp_list);
                }
        }
        mutex_exit(&ppp_compressors_mtx);

        return error;
}

int
ppp_unregister_compressor(struct compressor *pc, size_t ncomp)
{
        int error = 0;
        size_t i;

        mutex_enter(&ppp_compressors_mtx);
        for (i = 0; i < ncomp; i++) {
                if (ppp_get_compressor_noload(pc[i].compress_proto,
                        false) != &pc[i])
                        error = ENOENT;
                else if (pc[i].comp_refcnt != 0)
                        error = EBUSY;
        }
        if (!error) {
                for (i = 0; i < ncomp; i++) {
                        LIST_REMOVE(&pc[i], comp_list);
                }
        }
        mutex_exit(&ppp_compressors_mtx);

        return error;
}

/*
 * Module infrastructure
 */
#include "if_module.h"

#ifdef PPP_FILTER
#define PPP_DEP "bpf_filter,"
#else
#define PPP_DEP
#endif

IF_MODULE(MODULE_CLASS_DRIVER, ppp, PPP_DEP "slcompress")