dmake: do not set MAKEFLAGS=k

[unleashed/tickless.git] / usr / src / cmd / cmd-inet / usr.bin / pppd / ccp.c

/*
 * ccp.c - PPP Compression Control Protocol.
 *
 * Copyright (c) 2000 by Sun Microsystems, Inc.
 * All rights reserved.
 *
 * Copyright (c) 1994 The Australian National University.
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation is hereby granted, provided that the above copyright
 * notice appears in all copies.  This software is provided without any
 * warranty, express or implied. The Australian National University
 * makes no representations about the suitability of this software for
 * any purpose.
 *
 * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
 * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 * THE AUSTRALIAN NATIONAL UNIVERSITY HAVE BEEN ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
 * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
 * OR MODIFICATIONS.
 */
/*
 * Copyright (c) 2016 by Delphix. All rights reserved.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"
#define RCSID   "$Id: ccp.c,v 1.30 2000/04/15 01:27:11 masputra Exp $"

#include <stdlib.h>
#include <string.h>

#include "pppd.h"
#include "fsm.h"
#include "ccp.h"
#include <net/ppp-comp.h>

static const char rcsid[] = RCSID;

/*
 * Command-line options.
 */
static int setbsdcomp __P((char **, option_t *));
static int setdeflate __P((char **, option_t *));

static option_t ccp_option_list[] = {
    { "noccp", o_bool, &ccp_protent.enabled_flag,
      "Disable CCP negotiation" },
    { "-ccp", o_bool, &ccp_protent.enabled_flag,
      "Disable CCP negotiation" },
    { "bsdcomp", o_special, (void *)setbsdcomp,
      "Request BSD-Compress packet compression" },
    { "nobsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
      "don't allow BSD-Compress", OPT_A2COPY,
      &ccp_allowoptions[0].bsd_compress },
    { "-bsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
      "don't allow BSD-Compress", OPT_A2COPY,
      &ccp_allowoptions[0].bsd_compress },
    { "deflate", o_special, (void *)setdeflate,
      "request Deflate compression" },
    { "nodeflate", o_bool, &ccp_wantoptions[0].deflate,
      "don't allow Deflate compression", OPT_A2COPY,
      &ccp_allowoptions[0].deflate },
    { "-deflate", o_bool, &ccp_wantoptions[0].deflate,
      "don't allow Deflate compression", OPT_A2COPY,
      &ccp_allowoptions[0].deflate },
    { "nodeflatedraft", o_bool, &ccp_wantoptions[0].deflate_draft,
      "don't use draft deflate #", OPT_A2COPY,
      &ccp_allowoptions[0].deflate_draft },
    { "predictor1", o_bool, &ccp_wantoptions[0].predictor_1,
      "request Predictor-1", 1, &ccp_allowoptions[0].predictor_1 },
    { "nopredictor1", o_bool, &ccp_wantoptions[0].predictor_1,
      "don't allow Predictor-1", OPT_A2COPY,
      &ccp_allowoptions[0].predictor_1 },
    { "-predictor1", o_bool, &ccp_wantoptions[0].predictor_1,
      "don't allow Predictor-1", OPT_A2COPY,
      &ccp_allowoptions[0].predictor_1 },

    { NULL }
};

/*
 * Protocol entry points from main code.
 */
static void ccp_init __P((int unit));
static void ccp_open __P((int unit));
static void ccp_close __P((int unit, char *));
static void ccp_lowerup __P((int unit));
static void ccp_lowerdown __P((int));
static void ccp_input __P((int unit, u_char *pkt, int len));
static void ccp_protrej __P((int unit));
static int  ccp_printpkt __P((u_char *pkt, int len,
                              void (*printer) __P((void *, const char *, ...)),
                              void *arg));
static void ccp_datainput __P((int unit, u_char *pkt, int len));

struct protent ccp_protent = {
    PPP_CCP,
    ccp_init,
    ccp_input,
    ccp_protrej,
    ccp_lowerup,
    ccp_lowerdown,
    ccp_open,
    ccp_close,
    ccp_printpkt,
    ccp_datainput,
    1,
    "CCP",
    "Compressed",
    ccp_option_list,
    NULL,
    NULL,
    NULL
};

fsm ccp_fsm[NUM_PPP];
ccp_options ccp_wantoptions[NUM_PPP];   /* what to request the peer to use */
ccp_options ccp_gotoptions[NUM_PPP];    /* what the peer agreed to do */
ccp_options ccp_allowoptions[NUM_PPP];  /* what we'll agree to do */
ccp_options ccp_hisoptions[NUM_PPP];    /* what we agreed to do */

/*
 * Callbacks for fsm code.
 */
static void ccp_resetci __P((fsm *));
static int  ccp_cilen __P((fsm *));
static void ccp_addci __P((fsm *, u_char *, int *));
static int  ccp_ackci __P((fsm *, u_char *, int));
static int  ccp_nakci __P((fsm *, u_char *, int));
static int  ccp_rejci __P((fsm *, u_char *, int));
static int  ccp_reqci __P((fsm *, u_char *, int *, int));
static void ccp_up __P((fsm *));
static void ccp_down __P((fsm *));
static int  ccp_extcode __P((fsm *, int, int, u_char *, int));
static int  ccp_codereject __P((fsm *p, int code, int id, u_char *inp,
    int len));

static fsm_callbacks ccp_callbacks = {
    ccp_resetci,                /* Reset our Configuration Information */
    ccp_cilen,                  /* Length of our Configuration Information */
    ccp_addci,                  /* Add our Configuration Information */
    ccp_ackci,                  /* ACK our Configuration Information */
    ccp_nakci,                  /* NAK our Configuration Information */
    ccp_rejci,                  /* Reject our Configuration Information */
    ccp_reqci,                  /* Request peer's Configuration Information */
    ccp_up,                     /* Called when fsm reaches OPENED state */
    ccp_down,                   /* Called when fsm leaves OPENED state */
    NULL,                       /* Called when we want the lower layer up */
    NULL,                       /* Called when we want the lower layer down */
    NULL,                       /* Retransmission is necessary */
    ccp_extcode,                /* Called to handle LCP-specific codes */
    "CCP",                      /* String name of protocol */
    ccp_codereject,             /* Peer rejected a code number */
};

/*
 * Local statics.
 */
static void ccp_rack_timeout __P((void *));
static char * method_name __P((ccp_options *, ccp_options *));

/*
 * Do we want / did we get any compression?
 */
#define ANY_COMPRESS(opt)       ((opt).deflate || (opt).bsd_compress \
                                 || (opt).predictor_1 || (opt).predictor_2)

/*
 * Local state (mainly for handling reset-reqs and reset-acks).
 */
static int ccp_localstate[NUM_PPP];
#define RACK_PENDING    0x0001  /* waiting for reset-ack */
#define RREQ_REPEAT     0x0002  /* send another reset-req if no reset-ack */
#define RREQ_REJECTED   0x0004  /* peer code-rejected reset-request */
#define RACK_REJECTED   0x0008  /* peer code-rejected reset-ack */
#define RREQ_IGNORED    0x0010  /* peer just ignored reset-request */

#define RACKTIMEOUT     1       /* time in seconds between Reset-Requests */

static int all_rejected[NUM_PPP];       /* we rejected all peer's options */

#ifdef COMP_TUNE
static int deflate_tune = -1;   /* compression effort level for deflate */
#endif
static int deflate_rmax = DEFLATE_MAX_SIZE;     /* max rbits */
static int deflate_amax = DEFLATE_MAX_SIZE;     /* max abits */

/*
 * Option parsing.
 */
/*ARGSUSED*/
static int
setbsdcomp(argv, opt)
    char **argv;
    option_t *opt;
{
    int rbits, abits;
    char *str, *endp;

    str = *argv;
    abits = rbits = strtol(str, &endp, 0);
    if (endp != str && *endp == ',') {
        str = endp + 1;
        abits = strtol(str, &endp, 0);
    }
    if (*endp != '\0' || endp == str) {
        option_error("invalid parameter '%s' for bsdcomp option", *argv);
        return 0;
    }
    if ((rbits != 0 && (rbits < BSD_MIN_BITS || rbits > BSD_MAX_BITS))
        || (abits != 0 && (abits < BSD_MIN_BITS || abits > BSD_MAX_BITS))) {
        option_error("bsdcomp option values must be 0 or %d .. %d",
                     BSD_MIN_BITS, BSD_MAX_BITS);
        return 0;
    }
    if (rbits > 0) {
        ccp_wantoptions[0].bsd_compress = 1;
        ccp_wantoptions[0].bsd_bits = rbits;
    } else
        ccp_wantoptions[0].bsd_compress = 0;
    if (abits > 0) {
        ccp_allowoptions[0].bsd_compress = 1;
        ccp_allowoptions[0].bsd_bits = abits;
    } else
        ccp_allowoptions[0].bsd_compress = 0;
    return 1;
}

/*ARGSUSED*/
static int
setdeflate(argv, opt)
    char **argv;
    option_t *opt;
{
    int rbits, abits, def_rmax, def_amax;
    char *str, *endp;

    str = endp = *argv;
    if (*str == ',')
        abits = rbits = -1;
    else
        abits = rbits = strtol(str, &endp, 0);
    if (*endp == ',') {
        str = ++endp;
        if (*str == ',')
            abits = rbits;
        else
            abits = strtol(str, &endp, 0);
    }
#ifdef COMP_TUNE
    if (*endp == ',' && privileged_option) {
        str = ++endp;
        deflate_tune = strtol(str, &endp, 0);
    }
#endif
    if (*endp != '\0' || endp == str) {
        option_error("invalid parameter '%s' for deflate option", *argv);
        return 0;
    }
    if (privileged_option) {
        def_rmax = def_amax = DEFLATE_MAX_SIZE;
    } else {
        def_rmax = deflate_rmax;
        def_amax = deflate_amax;
    }
    if (rbits < 0)
        rbits = def_rmax;
    if (abits < 0)
        abits = def_amax;
    if ((rbits != 0 && (rbits <= DEFLATE_MIN_SIZE || rbits > def_rmax))
        || (abits != 0 && (abits <= DEFLATE_MIN_SIZE || abits > def_amax))) {
        option_error("deflate option values must be 0 or {%d,%d} .. {%d,%d}",
                     DEFLATE_MIN_SIZE+1, DEFLATE_MIN_SIZE+1,
                     def_rmax, def_amax);
        return 0;
    }
    if (privileged_option) {
        deflate_rmax = rbits;
        deflate_amax = abits;
    }
    if (rbits > 0) {
        ccp_wantoptions[0].deflate = 1;
        ccp_wantoptions[0].deflate_size = rbits;
    } else
        ccp_wantoptions[0].deflate = 0;
    if (abits > 0) {
        ccp_allowoptions[0].deflate = 1;
        ccp_allowoptions[0].deflate_size = abits;
    } else
        ccp_allowoptions[0].deflate = 0;
    return 1;
}


/*
 * ccp_init - initialize CCP.
 */
static void
ccp_init(unit)
    int unit;
{
    fsm *f = &ccp_fsm[unit];

    f->unit = unit;
    f->protocol = PPP_CCP;
    f->callbacks = &ccp_callbacks;
    fsm_init(f);
    f->flags |= OPT_RESTART;

    BZERO(&ccp_wantoptions[unit],  sizeof(ccp_options));
    BZERO(&ccp_gotoptions[unit],   sizeof(ccp_options));
    BZERO(&ccp_allowoptions[unit], sizeof(ccp_options));
    BZERO(&ccp_hisoptions[unit],   sizeof(ccp_options));

    ccp_wantoptions[0].deflate = 1;
    ccp_wantoptions[0].deflate_size = DEFLATE_MAX_SIZE;
    ccp_wantoptions[0].deflate_correct = 1;
    ccp_wantoptions[0].deflate_draft = 1;
    ccp_allowoptions[0].deflate = 1;
    ccp_allowoptions[0].deflate_size = DEFLATE_MAX_SIZE;
    ccp_allowoptions[0].deflate_correct = 1;
    ccp_allowoptions[0].deflate_draft = 1;

    ccp_wantoptions[0].bsd_compress = 1;
    ccp_wantoptions[0].bsd_bits = BSD_MAX_BITS;
    ccp_allowoptions[0].bsd_compress = 1;
    ccp_allowoptions[0].bsd_bits = BSD_MAX_BITS;

    ccp_allowoptions[0].predictor_1 = 1;
}

/*
 * ccp_open - CCP is allowed to come up.
 */
static void
ccp_open(unit)
    int unit;
{
    fsm *f = &ccp_fsm[unit];

    /*
     * If we haven't gone open yet (first time through), then go open
     * but not up.  Otherwise, skip this to allow reopen to reset the
     * compressor.
     */
    if (f->state != OPENED)
        ccp_flags_set(unit, 1, 0);

    /*
     * Find out which compressors the kernel supports before
     * deciding whether to open in silent mode.
     */
    ccp_resetci(f);
    if (!ANY_COMPRESS(ccp_gotoptions[unit]))
        f->flags |= OPT_SILENT;

    fsm_open(f);
}

/*
 * ccp_close - Terminate CCP.
 */
static void
ccp_close(unit, reason)
    int unit;
    char *reason;
{
    ccp_flags_set(unit, 0, 0);
    fsm_close(&ccp_fsm[unit], reason);
}

/*
 * ccp_lowerup - we may now transmit CCP packets.
 */
static void
ccp_lowerup(unit)
    int unit;
{
    fsm_lowerup(&ccp_fsm[unit]);
}

/*
 * ccp_lowerdown - we may not transmit CCP packets.
 */
static void
ccp_lowerdown(unit)
    int unit;
{
    fsm_lowerdown(&ccp_fsm[unit]);
}

/*
 * ccp_input - process a received CCP packet.
 */
static void
ccp_input(unit, p, len)
    int unit;
    u_char *p;
    int len;
{
    fsm *f = &ccp_fsm[unit];
    int oldstate;

    /*
     * Check for a terminate-request so we can print a message.
     */
    oldstate = f->state;
    fsm_input(f, p, len);
    if (oldstate == OPENED && p[0] == CODE_TERMREQ && f->state != OPENED)
        notice("Compression disabled by peer.");

    /*
     * If we get a terminate-ack and we're not asking for compression,
     * close CCP.  (Terminate-Request is handled by fsm_input() above.)
     */
    if (oldstate == REQSENT && p[0] == CODE_TERMACK
        && !ANY_COMPRESS(ccp_gotoptions[unit]))
        ccp_close(unit, "No compression negotiated");
}

/*
 * Handle a CCP-specific code.
 */
static int
ccp_extcode(f, code, id, p, len)
    fsm *f;
    int code, id;
    u_char *p;
    int len;
{
    switch (code) {
    case CCP_RESETREQ:
        /* If not open, then silently ignore. */
        if (f->state != OPENED)
            break;
        /* send a reset-ack, which our transmitter module will see and
           reset its compression state. */
        fsm_sdata(f, CCP_RESETACK, id, p, len);
        break;

    case CCP_RESETACK:
        /*
         * Note that the compression module isn't picky about ID
         * numbers and such.
         */
        ccp_localstate[f->unit] &= ~RREQ_IGNORED & ~RREQ_REJECTED;
        if ((ccp_localstate[f->unit] & RACK_PENDING) && id == f->reqid) {
            ccp_localstate[f->unit] &= ~RACK_PENDING & ~RREQ_REPEAT;
            UNTIMEOUT(ccp_rack_timeout, f);
        }
        break;

    default:
        /* Tell fsm to send code reject */
        return (0);
    }

    return (1);
}

/*
 * Handle Code-Reject for one of our extended codes by dropping back to
 * reopen as mechanism to restart compression.
 */
/*ARGSUSED*/
static int
ccp_codereject(f, code, id, inp, len)
    fsm *f;
    int code, id;
    u_char *inp;
    int len;
{
    switch (code) {
    case CCP_RESETREQ:
        if (!(ccp_localstate[f->unit] & RREQ_REJECTED)) {
            info("peer has rejected CCP Reset-Request; falling back on Open");
            if (f->state == OPENED)
                ccp_open(f->unit);
        }
        ccp_localstate[f->unit] |= RREQ_REJECTED;
        return (0);

    case CCP_RESETACK:
        /*
         * Peer must have sent us CCP Reset-Request but then code-rejected when
         * we sent CCP Reset-Ack.  It seems to have changed its mind, and we
         * have to obey its wishes.
         */
        ccp_localstate[f->unit] |= RACK_REJECTED;
        notice("peer has erroneously rejected CCP Reset-Ack");
        f->term_reason = "peer sent Code-Reject for CCP Reset-Ack";
        f->term_reason_len = strlen(f->term_reason);
        break;

    default:
        f->term_reason = "peer sent invalid Code-Reject";
        break;
    }

    f->term_reason_len = strlen(f->term_reason);
    return (1);
}

/*
 * ccp_protrej - peer doesn't talk CCP.
 */
static void
ccp_protrej(unit)
    int unit;
{
    /* Neither open nor up. */
    ccp_flags_set(unit, 0, 0);
    fsm_lowerdown(&ccp_fsm[unit]);
}

/*
 * ccp_resetci - initialize at start of negotiation.
 */
static void
ccp_resetci(f)
    fsm *f;
{
    ccp_options *go = &ccp_gotoptions[f->unit];
    u_char opt_buf[16];

    *go = ccp_wantoptions[f->unit];
    all_rejected[f->unit] = 0;

    /*
     * Check whether the kernel knows about the various
     * decompression methods we might request.
     */
    if (go->bsd_compress) {
        opt_buf[0] = CI_BSD_COMPRESS;
        opt_buf[1] = CILEN_BSD_COMPRESS;
        opt_buf[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, BSD_MIN_BITS);
        if (ccp_test(f->unit, opt_buf, CILEN_BSD_COMPRESS, 0) <= 0)
            go->bsd_compress = 0;
    }
    if (go->deflate) {
        if (go->deflate_correct) {
            opt_buf[0] = CI_DEFLATE;
            opt_buf[1] = CILEN_DEFLATE;
            opt_buf[2] = DEFLATE_MAKE_OPT(DEFLATE_MIN_SIZE+1);
            opt_buf[3] = DEFLATE_CHK_SEQUENCE;
            if (ccp_test(f->unit, opt_buf, CILEN_DEFLATE, 0) <= 0)
                go->deflate_correct = 0;
        }
        if (go->deflate_draft) {
            opt_buf[0] = CI_DEFLATE_DRAFT;
            opt_buf[1] = CILEN_DEFLATE;
            opt_buf[2] = DEFLATE_MAKE_OPT(DEFLATE_MIN_SIZE+1);
            opt_buf[3] = DEFLATE_CHK_SEQUENCE;
            if (ccp_test(f->unit, opt_buf, CILEN_DEFLATE, 0) <= 0)
                go->deflate_draft = 0;
        }
        if (!go->deflate_correct && !go->deflate_draft)
            go->deflate = 0;
    }
    if (go->predictor_1) {
        opt_buf[0] = CI_PREDICTOR_1;
        opt_buf[1] = CILEN_PREDICTOR_1;
        if (ccp_test(f->unit, opt_buf, CILEN_PREDICTOR_1, 0) <= 0)
            go->predictor_1 = 0;
    }
    if (go->predictor_2) {
        opt_buf[0] = CI_PREDICTOR_2;
        opt_buf[1] = CILEN_PREDICTOR_2;
        if (ccp_test(f->unit, opt_buf, CILEN_PREDICTOR_2, 0) <= 0)
            go->predictor_2 = 0;
    }
}

/*
 * ccp_cilen - Return total length of our configuration info.
 */
static int
ccp_cilen(f)
    fsm *f;
{
    ccp_options *go = &ccp_gotoptions[f->unit];

    return (go->bsd_compress? CILEN_BSD_COMPRESS: 0)
        + (go->deflate && go->deflate_correct ? CILEN_DEFLATE : 0)
        + (go->deflate && go->deflate_draft ? CILEN_DEFLATE : 0)
        + (go->predictor_1? CILEN_PREDICTOR_1: 0)
        + (go->predictor_2? CILEN_PREDICTOR_2: 0);
}

/*
 * ccp_addci - put our requests in a packet.
 */
static void
ccp_addci(f, p, lenp)
    fsm *f;
    u_char *p;
    int *lenp;
{
    int res;
    ccp_options *go = &ccp_gotoptions[f->unit];
    u_char *p0 = p;

    /*
     * Add the compression types that we can receive, in decreasing
     * preference order.  Get the kernel to allocate the first one
     * in case it gets Acked.
     */
    if (go->deflate) {
        p[0] = go->deflate_correct? CI_DEFLATE: CI_DEFLATE_DRAFT;
        p[1] = CILEN_DEFLATE;
        p[2] = DEFLATE_MAKE_OPT(go->deflate_size);
        p[3] = DEFLATE_CHK_SEQUENCE;
        for (;;) {
            res = ccp_test(f->unit, p, CILEN_DEFLATE, 0);
            if (res > 0) {
                p += CILEN_DEFLATE;
                break;
            }
            if (res < 0 || go->deflate_size <= DEFLATE_MIN_SIZE+1) {
                go->deflate = 0;
                break;
            }
            --go->deflate_size;
            p[2] = DEFLATE_MAKE_OPT(go->deflate_size);
        }
        /* If we're offering both, then this is second. */
        if (p != p0 && go->deflate_correct && go->deflate_draft) {
            p[0] = CI_DEFLATE_DRAFT;
            p[1] = CILEN_DEFLATE;
            p[2] = p[2 - CILEN_DEFLATE];
            p[3] = DEFLATE_CHK_SEQUENCE;
            p += CILEN_DEFLATE;
        }
    }
    if (go->bsd_compress) {
        p[0] = CI_BSD_COMPRESS;
        p[1] = CILEN_BSD_COMPRESS;
        p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits);
        if (p != p0) {
            p += CILEN_BSD_COMPRESS;    /* not the first option */
        } else {
            for (;;) {
                res = ccp_test(f->unit, p, CILEN_BSD_COMPRESS, 0);
                if (res > 0) {
                    p += CILEN_BSD_COMPRESS;
                    break;
                }
                if (res < 0 || go->bsd_bits <= BSD_MIN_BITS) {
                    go->bsd_compress = 0;
                    break;
                }
                --go->bsd_bits;
                p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits);
            }
        }
    }
    /*
     * Prefer Predictor-1 over Predictor-2.  (The latter requires the use
     * of LAP-B and has no known implementations.)
     */
    if (go->predictor_1) {
        p[0] = CI_PREDICTOR_1;
        p[1] = CILEN_PREDICTOR_1;
        if (p == p0 && ccp_test(f->unit, p, CILEN_PREDICTOR_1, 0) <= 0) {
            go->predictor_1 = 0;
        } else {
            p += CILEN_PREDICTOR_1;
        }
    }
    if (go->predictor_2) {
        p[0] = CI_PREDICTOR_2;
        p[1] = CILEN_PREDICTOR_2;
        if (p == p0 && ccp_test(f->unit, p, CILEN_PREDICTOR_2, 0) <= 0) {
            go->predictor_2 = 0;
        } else {
            p += CILEN_PREDICTOR_2;
        }
    }

    go->method = (p > p0)? p0[0]: -1;

    *lenp = p - p0;
}

/*
 * ccp_ackci - process a received configure-ack, and return
 * 1 iff the packet was OK.
 */
static int
ccp_ackci(f, p, len)
    fsm *f;
    u_char *p;
    int len;
{
    ccp_options *go = &ccp_gotoptions[f->unit];
    u_char *p0 = p;

    if (go->deflate && go->deflate_correct) {
        if (len < CILEN_DEFLATE
            || p[0] != CI_DEFLATE || p[1] != CILEN_DEFLATE
            || p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
            || p[3] != DEFLATE_CHK_SEQUENCE)
            return 0;
        /* Cope with non-standard first/fast ack */
        if (p == p0 && len == 0)
            return 1;
        p += CILEN_DEFLATE;
        len -= CILEN_DEFLATE;
    }
    if (go->deflate && go->deflate_draft) {
        if (len < CILEN_DEFLATE
            || p[0] != CI_DEFLATE_DRAFT || p[1] != CILEN_DEFLATE
            || p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
            || p[3] != DEFLATE_CHK_SEQUENCE)
            return 0;
        /* Cope with non-standard first/fast ack */
        if (p == p0 && len == 0)
            return 1;
        p += CILEN_DEFLATE;
        len -= CILEN_DEFLATE;
    }
    if (go->bsd_compress) {
        if (len < CILEN_BSD_COMPRESS
            || p[0] != CI_BSD_COMPRESS || p[1] != CILEN_BSD_COMPRESS
            || p[2] != BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits))
            return 0;
        /* Cope with non-standard first/fast ack */
        if (p == p0 && len == 0)
            return 1;
        p += CILEN_BSD_COMPRESS;
        len -= CILEN_BSD_COMPRESS;
    }
    if (go->predictor_1) {
        if (len < CILEN_PREDICTOR_1
            || p[0] != CI_PREDICTOR_1 || p[1] != CILEN_PREDICTOR_1)
            return 0;
        /* Cope with non-standard first/fast ack */
        if (p == p0 && len == 0)
            return 1;
        p += CILEN_PREDICTOR_1;
        len -= CILEN_PREDICTOR_1;
    }
    if (go->predictor_2) {
        if (len < CILEN_PREDICTOR_2
            || p[0] != CI_PREDICTOR_2 || p[1] != CILEN_PREDICTOR_2)
            return 0;
        /* Cope with non-standard first/fast ack */
        if (p == p0 && len == 0)
            return 1;
        p += CILEN_PREDICTOR_2;
        len -= CILEN_PREDICTOR_2;
    }

    /* Peer cannot ack something that wasn't sent. */
    if (len != 0)
        return 0;
    return 1;
}

/*
 * ccp_nakci - process received configure-nak.
 * Returns 1 iff the nak was OK.
 */
static int
ccp_nakci(f, p, len)
    fsm *f;
    u_char *p;
    int len;
{
    ccp_options *go = &ccp_gotoptions[f->unit];
    ccp_options no;             /* options we've seen already */
    ccp_options try;            /* options to ask for next time */

    BZERO(&no, sizeof(no));
    try = *go;

    if (go->deflate && go->deflate_correct && len >= CILEN_DEFLATE &&
        p[0] == CI_DEFLATE) {
        no.deflate = 1;
        /*
         * Peer wants us to use a different code size or something.
         * Stop asking for Deflate if we don't understand its suggestion.
         */
        if (p[1] != CILEN_DEFLATE
            || DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL
            || DEFLATE_SIZE(p[2]) <= DEFLATE_MIN_SIZE
            || p[3] != DEFLATE_CHK_SEQUENCE)
            try.deflate_correct = 0;
        else if (DEFLATE_SIZE(p[2]) < go->deflate_size)
            try.deflate_size = DEFLATE_SIZE(p[2]);
        len -= p[1];
        p += p[1];
    }

    if (go->deflate && go->deflate_draft && len >= CILEN_DEFLATE &&
        p[0] == CI_DEFLATE_DRAFT) {
        no.deflate = 1;
        /*
         * Peer wants us to use a different code size or something.
         * Stop asking for Deflate using the old algorithm number if
         * we don't understand its suggestion.  (Note that this will
         * happen if the peer is running Magnalink instead of
         * old-style Deflate.)
         */
        if (p[1] != CILEN_DEFLATE
            || DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL
            || DEFLATE_SIZE(p[2]) <= DEFLATE_MIN_SIZE
            || p[3] != DEFLATE_CHK_SEQUENCE)
            try.deflate_draft = 0;
        else if (DEFLATE_SIZE(p[2]) < go->deflate_size)
            try.deflate_size = DEFLATE_SIZE(p[2]);
        len -= p[1];
        p += p[1];
    }

    if (!try.deflate_correct && !try.deflate_draft)
        try.deflate = 0;

    if (go->bsd_compress && len >= CILEN_BSD_COMPRESS &&
        p[0] == CI_BSD_COMPRESS) {
        no.bsd_compress = 1;
        /*
         * Peer wants us to use a different number of bits
         * or a different version.
         */
        if (p[1] != CILEN_BSD_COMPRESS ||
            BSD_VERSION(p[2]) != BSD_CURRENT_VERSION)
            try.bsd_compress = 0;
        else if (BSD_NBITS(p[2]) < go->bsd_bits)
            try.bsd_bits = BSD_NBITS(p[2]);
        len -= p[1];
        p += p[1];
    }

    /*
     * Predictor-1 and 2 have no options, so they can't be Naked.
     *
     * There may be remaining options but we ignore them.
     */

    if (f->state != OPENED)
        *go = try;
    return 1;
}

/*
 * ccp_rejci - peer rejects some of our suggested compression methods.
 */
static int
ccp_rejci(f, p, len)
    fsm *f;
    u_char *p;
    int len;
{
    ccp_options *go = &ccp_gotoptions[f->unit];
    ccp_options try;            /* options to request next time */

    try = *go;

    /*
     * Cope with empty configure-rejects by ceasing to send
     * configure-requests.
     */
    if (len == 0 && all_rejected[f->unit])
        return -1;

    if (go->deflate && go->deflate_correct && len >= CILEN_DEFLATE &&
        p[0] == CI_DEFLATE && p[1] == CILEN_DEFLATE) {
        if (p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
            || p[3] != DEFLATE_CHK_SEQUENCE)
            return 0;           /* Rej is bad */
        try.deflate_correct = 0;
        p += CILEN_DEFLATE;
        len -= CILEN_DEFLATE;
    }
    if (go->deflate && go->deflate_draft && len >= CILEN_DEFLATE &&
        p[0] == CI_DEFLATE_DRAFT && p[1] == CILEN_DEFLATE) {
        if (p[2] != DEFLATE_MAKE_OPT(go->deflate_size)
            || p[3] != DEFLATE_CHK_SEQUENCE)
            return 0;           /* Rej is bad */
        try.deflate_draft = 0;
        p += CILEN_DEFLATE;
        len -= CILEN_DEFLATE;
    }
    if (!try.deflate_correct && !try.deflate_draft)
        try.deflate = 0;
    if (go->bsd_compress && len >= CILEN_BSD_COMPRESS
        && p[0] == CI_BSD_COMPRESS && p[1] == CILEN_BSD_COMPRESS) {
        if (p[2] != BSD_MAKE_OPT(BSD_CURRENT_VERSION, go->bsd_bits))
            return 0;
        try.bsd_compress = 0;
        p += CILEN_BSD_COMPRESS;
        len -= CILEN_BSD_COMPRESS;
    }
    if (go->predictor_1 && len >= CILEN_PREDICTOR_1
        && p[0] == CI_PREDICTOR_1 && p[1] == CILEN_PREDICTOR_1) {
        try.predictor_1 = 0;
        p += CILEN_PREDICTOR_1;
        len -= CILEN_PREDICTOR_1;
    }
    if (go->predictor_2 && len >= CILEN_PREDICTOR_2
        && p[0] == CI_PREDICTOR_2 && p[1] == CILEN_PREDICTOR_2) {
        try.predictor_2 = 0;
        p += CILEN_PREDICTOR_2;
        len -= CILEN_PREDICTOR_2;
    }

    if (len != 0)
        return 0;

    if (f->state != OPENED)
        *go = try;

    return 1;
}

/*
 * ccp_reqci - process a received configure-request.
 *
 * Returns CODE_CONFACK, CODE_CONFNAK or CODE_CONFREJ and the packet
 * is modified appropriately.
 */
static int
ccp_reqci(f, p, lenp, dont_nak)
    fsm *f;
    u_char *p;
    int *lenp;
    int dont_nak;
{
    int ret, newret, res;
    u_char *p0, *nakp, *rejp, *pv;
    int len, clen, type, nb;
    ccp_options *ho = &ccp_hisoptions[f->unit];
    ccp_options *ao = &ccp_allowoptions[f->unit];

    ret = CODE_CONFACK;
    rejp = p0 = p;
    nakp = nak_buffer;
    len = *lenp;

    BZERO(ho, sizeof(ccp_options));
    ho->method = (len > 0)? p[0]: -1;

    for (; len > 0; len -= clen, p += clen) {
        newret = CODE_CONFACK;
        if (len < 2 || p[1] > len) {
            /*
             * RFC 1661 page 40 -- if the option extends beyond the
             * packet, then discard the entire packet.
             */
            return (0);
        }

        type = p[0];
        clen = p[1];

        pv = p;
        switch (type) {
        case CI_DEFLATE:
        case CI_DEFLATE_DRAFT:
            if (!ao->deflate ||
                (!ao->deflate_correct && type == CI_DEFLATE) ||
                (!ao->deflate_draft && type == CI_DEFLATE_DRAFT)) {
                newret = CODE_CONFREJ;
                break;
            }

            ho->deflate = 1;
            nb = clen < CILEN_DEFLATE ? ao->deflate_size : DEFLATE_SIZE(p[2]);
            ho->deflate_size = nb;
            if (clen != CILEN_DEFLATE ||
                DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL ||
                p[3] != DEFLATE_CHK_SEQUENCE || nb > ao->deflate_size ||
                nb <= DEFLATE_MIN_SIZE) {
                newret = CODE_CONFNAK;
                if (dont_nak)
                    break;
                if (nb > ao->deflate_size)
                    nb = ao->deflate_size;
                else if (nb <= DEFLATE_MIN_SIZE)
                    nb = DEFLATE_MIN_SIZE+1;
                pv = nakp;
                PUTCHAR(type, nakp);
                PUTCHAR(CILEN_DEFLATE, nakp);
                PUTCHAR(DEFLATE_MAKE_OPT(nb), nakp);
                PUTCHAR(DEFLATE_CHK_SEQUENCE, nakp);
            }

            /*
             * Check whether we can do Deflate with the window
             * size they want.  If the window is too big, reduce
             * it until the kernel can cope and nak with that.
             * We only check this for the first option.
             */
            if (p == p0) {
                for (;;) {
                    res = ccp_test(f->unit, pv, CILEN_DEFLATE, 1);
                    if (res > 0)
                        break;          /* it's OK now */
                    if (res < 0 || nb <= DEFLATE_MIN_SIZE+1 || dont_nak) {
                        newret = CODE_CONFREJ;
                        break;
                    }
                    if (newret == CODE_CONFACK) {
                        BCOPY(pv, nakp, CILEN_DEFLATE);
                        pv = nakp;
                        nakp += CILEN_DEFLATE;
                        newret = CODE_CONFNAK;
                    }
                    --nb;
                    pv[2] = DEFLATE_MAKE_OPT(nb);
                }
#ifdef COMP_TUNE
                /* Tune Deflate compression effort. */
                if (newret == CODE_CONFACK)
                    ccp_tune(f->unit, deflate_tune);
#endif
            }
            break;

        case CI_BSD_COMPRESS:
            if (!ao->bsd_compress) {
                newret = CODE_CONFREJ;
                break;
            }

            ho->bsd_compress = 1;
            nb = clen < CILEN_BSD_COMPRESS ? ao->bsd_bits : BSD_NBITS(p[2]);
            ho->bsd_bits = nb;
            if (clen != CILEN_BSD_COMPRESS ||
                BSD_VERSION(p[2]) != BSD_CURRENT_VERSION ||
                nb > ao->bsd_bits || nb < BSD_MIN_BITS) {
                newret = CODE_CONFNAK;
                if (dont_nak)
                    break;
                if (nb > ao->bsd_bits)
                    nb = ao->bsd_bits;
                else if (nb < BSD_MIN_BITS)
                    nb = BSD_MIN_BITS;
                pv = nakp;
                PUTCHAR(type, nakp);
                PUTCHAR(CILEN_BSD_COMPRESS, nakp);
                PUTCHAR(BSD_MAKE_OPT(BSD_CURRENT_VERSION, nb), nakp);
            }

            /*
             * Check whether we can do BSD-Compress with the code
             * size they want.  If the code size is too big, reduce
             * it until the kernel can cope and nak with that.
             * We only check this for the first option.
             */
            if (p == p0) {
                for (;;) {
                    res = ccp_test(f->unit, pv, CILEN_BSD_COMPRESS, 1);
                    if (res > 0)
                        break;
                    if (res < 0 || nb == BSD_MIN_BITS || dont_nak) {
                        newret = CODE_CONFREJ;
                        break;
                    }
                    if (newret == CODE_CONFACK) {
                        BCOPY(pv, nakp, CILEN_BSD_COMPRESS);
                        pv = nakp;
                        nakp += CILEN_BSD_COMPRESS;
                        newret = CODE_CONFNAK;
                    }
                    --nb;
                    pv[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, nb);
                }
            }
            break;

        case CI_PREDICTOR_1:
            if (!ao->predictor_1) {
                newret = CODE_CONFREJ;
                break;
            }

            ho->predictor_1 = 1;
            if (clen != CILEN_PREDICTOR_1) {
                newret = CODE_CONFNAK;
                if (dont_nak)
                    break;
                pv = nakp;
                PUTCHAR(type, nakp);
                PUTCHAR(CILEN_PREDICTOR_1, nakp);
            }
            if (p == p0 &&
                ccp_test(f->unit, pv, CILEN_PREDICTOR_1, 1) <= 0) {
                newret = CODE_CONFREJ;
            }
            break;

        case CI_PREDICTOR_2:
            if (!ao->predictor_2) {
                newret = CODE_CONFREJ;
                break;
            }

            ho->predictor_2 = 1;
            if (clen != CILEN_PREDICTOR_2) {
                newret = CODE_CONFNAK;
                if (dont_nak)
                    break;
                pv = nakp;
                PUTCHAR(type, nakp);
                PUTCHAR(CILEN_PREDICTOR_2, nakp);
            }
            if (p == p0 &&
                ccp_test(f->unit, p, CILEN_PREDICTOR_2, 1) <= 0) {
                newret = CODE_CONFREJ;
            }
            break;

        default:
            newret = CODE_CONFREJ;
            break;
        }

        /* Cope with confused peers. */
        if (clen < 2)
            clen = 2;

        if (newret == CODE_CONFACK && ret != CODE_CONFACK)
            continue;
        if (newret == CODE_CONFNAK) {
            if (dont_nak) {
                newret = CODE_CONFREJ;
            } else {
                /* Ignore subsequent nakable things if rejecting. */
                if (ret == CODE_CONFREJ)
                    continue;
                ret = CODE_CONFNAK;
            }
        }
        if (newret == CODE_CONFREJ) {
            ret = CODE_CONFREJ;
            if (p != rejp)
                BCOPY(p, rejp, clen);
            rejp += clen;
        }
    }

    switch (ret) {
    case CODE_CONFACK:
        *lenp = p - p0;
        break;
    case CODE_CONFNAK:
        *lenp = nakp - nak_buffer;
        BCOPY(nak_buffer, p0, *lenp);
        break;
    case CODE_CONFREJ:
        *lenp = rejp - p0;
        break;
    }
    return ret;
}

/*
 * Make a string name for a compression method (or 2).
 */
static char *
method_name(opt, opt2)
    ccp_options *opt, *opt2;
{
    static char result[64];

    if (!ANY_COMPRESS(*opt))
        return "(none)";
    switch (opt->method) {
    case CI_DEFLATE:
    case CI_DEFLATE_DRAFT:
        if (opt2 != NULL && opt2->deflate_size != opt->deflate_size)
            (void) slprintf(result, sizeof(result), "Deflate%s (%d/%d)",
                     (opt->method == CI_DEFLATE_DRAFT? "(old#)": ""),
                     opt->deflate_size, opt2->deflate_size);
        else
            (void) slprintf(result, sizeof(result), "Deflate%s (%d)",
                     (opt->method == CI_DEFLATE_DRAFT? "(old#)": ""),
                     opt->deflate_size);
        break;
    case CI_BSD_COMPRESS:
        if (opt2 != NULL && opt2->bsd_bits != opt->bsd_bits)
            (void) slprintf(result, sizeof(result), "BSD-Compress (%d/%d)",
                     opt->bsd_bits, opt2->bsd_bits);
        else
            (void) slprintf(result, sizeof(result), "BSD-Compress (%d)",
                     opt->bsd_bits);
        break;
    case CI_PREDICTOR_1:
        return "Predictor 1";
    case CI_PREDICTOR_2:
        return "Predictor 2";
#ifdef CI_STAC
    case CI_STAC:
        return "Stac";
#endif
#ifdef CI_MPPC
    case CI_MPPC:
        return "MS-PPC";
#endif
    default:
        (void) slprintf(result, sizeof(result), "Method %d", opt->method);
    }
    return result;
}

/*
 * CCP has come up - inform the kernel driver and log a message.
 */
static void
ccp_up(f)
    fsm *f;
{
    ccp_options *go = &ccp_gotoptions[f->unit];
    ccp_options *ho = &ccp_hisoptions[f->unit];
    char method1[64];

    /*
     * We're now open and up (running).
     */
    ccp_flags_set(f->unit, 1, 1);
    if (ANY_COMPRESS(*go)) {
        if (ANY_COMPRESS(*ho)) {
            if (go->method == ho->method) {
                notice("%s compression enabled", method_name(go, ho));
            } else {
                (void) strlcpy(method1, method_name(go, NULL), sizeof(method1));
                notice("%s / %s compression enabled",
                       method1, method_name(ho, NULL));
            }
        } else
            notice("%s receive decompression enabled", method_name(go, NULL));
    } else if (ANY_COMPRESS(*ho))
        notice("%s transmit compression enabled", method_name(ho, NULL));
}

/*
 * CCP has gone down - inform the kernel driver.
 */
static void
ccp_down(f)
    fsm *f;
{
    if (ccp_localstate[f->unit] & RACK_PENDING)
        UNTIMEOUT(ccp_rack_timeout, f);
    /* Don't forget about peer's code rejects or ignoring of requests. */
    ccp_localstate[f->unit] &= ~RACK_PENDING & ~RREQ_REPEAT;
    /* We're still open, but no longer up. */
    ccp_flags_set(f->unit, 1, 0);
}

static int
ccp_printpkt(p, plen, printer, arg)
    u_char *p;
    int plen;
    void (*printer) __P((void *, const char *, ...));
    void *arg;
{
    u_char *p0, *optend, cichar;
    int code, id, len;
    int optlen, clen;
    u_short cishort;
#ifdef CI_MPPC
    u_int32_t cilong;
#endif

    p0 = p;
    if (plen < HEADERLEN) {
        printer(arg, "too short (%d<%d)", plen, HEADERLEN);
        return (0);
    }
    GETCHAR(code, p);
    GETCHAR(id, p);
    GETSHORT(len, p);

    printer(arg, " %s id=0x%x", code_name(code, 1), id);

    if (len < HEADERLEN) {
        printer(arg, " header length %d<%d", len, HEADERLEN);
        return (HEADERLEN);
    }
    if (len > plen) {
        printer(arg, " truncated (%d>%d)", len, plen);
        len = plen;
    }
    len -= HEADERLEN;

    switch (code) {
    case CODE_CONFREQ:
    case CODE_CONFACK:
    case CODE_CONFNAK:
    case CODE_CONFREJ:
        /* print list of possible compression methods */
        while (len >= 2) {
            GETCHAR(code, p);
            GETCHAR(clen, p);
            optlen = clen;
            printer(arg, " <");
            if (optlen > len)
                optlen = len;
            if (optlen < 2)
                optlen = 2;
            len -= optlen;
            optend = p + optlen - 2;
            switch (code) {
            case CI_DEFLATE:
            case CI_DEFLATE_DRAFT:
                printer(arg, "deflate%s",
                    (code == CI_DEFLATE_DRAFT? "(old#)": ""));
                if (clen != CILEN_DEFLATE)
                    printer(arg, " length %d", clen);
                if (optlen >= CILEN_DEFLATE) {
                    GETCHAR(cichar, p);
                    printer(arg, " %d", DEFLATE_SIZE(cichar));
                    if (DEFLATE_METHOD(cichar) != DEFLATE_METHOD_VAL)
                        printer(arg, " method %d", DEFLATE_METHOD(cichar));
                    GETCHAR(cichar, p);
                    if (cichar != DEFLATE_CHK_SEQUENCE)
                        printer(arg, " check %d", cichar);
                }
                break;
            case CI_BSD_COMPRESS:
                printer(arg, "bsd");
                if (clen != CILEN_BSD_COMPRESS)
                    printer(arg, " length %d", clen);
                if (optlen >= CILEN_BSD_COMPRESS) {
                    GETCHAR(cichar, p);
                    printer(arg, " v%d %d", BSD_VERSION(cichar),
                        BSD_NBITS(cichar));
                }
                break;
            case CI_PREDICTOR_1:
                printer(arg, "predictor-1");
                if (clen != CILEN_PREDICTOR_1)
                    printer(arg, " length %d", clen);
                break;
            case CI_PREDICTOR_2:
                printer(arg, "predictor-2");
                if (clen != CILEN_PREDICTOR_2)
                    printer(arg, " length %d", clen);
                break;
#ifdef CI_STAC
            case CI_STAC:
                printer(arg, "Stac");
                if (clen != CILEN_STAC)
                    printer(arg, " length %d", clen);
                if (optlen >= CILEN_STAC) {
                    GETSHORT(cishort, p);
                    GETCHAR(cichar, p);
                    printer(arg, " h%d/m%d", cishort, cichar);
                }
                break;
#endif
#ifdef CI_MPPC
            case CI_MPPC:
                /* There appears to be no good generic name for this one. */
                if (optlen >= CILEN_MPPC) {
                    GETLONG(cilong, p);
                    if (!(cilong & MPPC_COMP)) {
                        if (cilong & MPPC_MPPE)
                            printer(arg, "MPPE");
                        else
                            printer(arg, "MS-PPC?");
                    } else {
                        if (cilong & MPPC_MPPE)
                            printer(arg, "MPPC+MPPE");
                        else
                            printer(arg, "MPPC");
                    }
                } else {
                    printer(arg, "MS-?");
                }
                if (clen != CILEN_STAC)
                    printer(arg, " length %d", clen);
                break;
#endif
            default:
                printer(arg, "typ%d len%d ", code, clen);
                break;
            }
            if (p < optend) {
                if (p+8 < optend)
                    printer(arg, " %.8B ...", p);
                else
                    printer(arg, " %.*B", optend-p, p);
                p = optend;
            }
            printer(arg, ">");
        }
        break;

    case CODE_TERMACK:
    case CODE_TERMREQ:
        if (len > 0) {
            if (len == 2) {
                GETSHORT(cishort, p);
                printer(arg, " history %d", cishort);
                len = 0;
            } else if (*p >= ' ' && *p < 0x7f) {
                printer(arg, " ");
                print_string((char *)p, len, printer, arg);
                p += len;
                len = 0;
            }
        }
        break;
    }

    /* dump out the rest of the packet in hex */
    if (len > 0) {
        if (len > 8)
            printer(arg, " %.8B ...", p);
        else
            printer(arg, " %.*B", len, p);
        p += len;
    }

    return p - p0;
}

/*
 * We have received a packet that the decompressor failed to
 * decompress.  Here we would expect to issue a reset-request, but
 * Motorola has a patent on resetting the compressor as a result of
 * detecting an error in the decompressed data after decompression.
 * (See US patent 5,130,993; international patent publication number
 * WO 91/10289; Australian patent 73296/91.)
 *
 * So we ask the kernel whether the error was detected after
 * decompression; if it was, we take CCP down, thus disabling
 * compression :-(, otherwise we issue the reset-request.
 */
/*ARGSUSED*/
static void
ccp_datainput(unit, pkt, len)
    int unit;
    u_char *pkt;
    int len;
{
    fsm *f;

    f = &ccp_fsm[unit];
    if (f->state == OPENED) {
        if (ccp_fatal_error(unit)) {
            /*
             * Disable compression by taking CCP down.
             */
            error("Lost compression sync: disabling compression");
            ccp_close(unit, "Lost compression sync");
        } else {
            /*
             * Send a reset-request to reset the peer's compressor, if
             * possible.  We don't do anything if we are still waiting
             * for an acknowledgement to a previous reset-request (to
             * avoid flooding the peer).  We reopen CCP if the peer
             * doesn't like hearing about CCP Reset-Request (Cisco
             * sends CCP Code-Reject for Reset-Request).  (Reopen
             * automatically clears the flags and cancels the
             * timeout.)
             */
            if (ccp_localstate[f->unit] & RREQ_REJECTED) {
                dbglog("reopening CCP to reset peer's compressor");
                ccp_open(f->unit);
            } else if (ccp_localstate[f->unit] & RACK_PENDING) {
                /* Send another reset request; we're out of sequence. */
                ccp_localstate[f->unit] |= RREQ_REPEAT;
            } else {
                dbglog("sending CCP Reset-Request to reset peer's compressor");
                fsm_sdata(f, CCP_RESETREQ, f->reqid = ++f->id, NULL, 0);
                TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
                ccp_localstate[f->unit] |= RACK_PENDING;
            }
        }
    }
}

/*
 * Timeout waiting for reset-ack.
 */
static void
ccp_rack_timeout(arg)
    void *arg;
{
    fsm *f = arg;

    /* Timeout; no longer pending. */
    ccp_localstate[f->unit] &= ~RACK_PENDING;

    /* Frankly, it's a coding flaw if this occurs. */
    if (f->state != OPENED)
        return;

    if (ccp_localstate[f->unit] & RREQ_IGNORED) {
        info("peer ignored our CCP Reset-Request twice; reopen instead");
        ccp_localstate[f->unit] =
            (ccp_localstate[f->unit] & ~RREQ_IGNORED) | RREQ_REJECTED;
        ccp_open(f->unit);
    } else if (ccp_localstate[f->unit] & RREQ_REPEAT) {
        dbglog("sending another CCP Reset-Request on timeout");
        fsm_sdata(f, CCP_RESETREQ, f->reqid, NULL, 0);
        TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
        ccp_localstate[f->unit] =
            (ccp_localstate[f->unit] & ~RREQ_REPEAT) | RREQ_IGNORED |
            RACK_PENDING;
    } else {
        dbglog("timeout waiting for CCP Reset-Ack; hope for the best");
        ccp_localstate[f->unit] |= RREQ_IGNORED;
    }
}