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ccp.c

/*
 * ccp.c - PPP Compression Control Protocol.
 *
 * 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.
 */

#ifndef lint
static char rcsid[] = "$FreeBSD: src/usr.sbin/pppd/ccp.c,v 1.10.52.1 2008/11/25 02:59:29 kensmith Exp $";
#endif

#include <string.h>
#include <syslog.h>
#include <sys/ioctl.h>
#include <sys/types.h>

#include "pppd.h"
#include "fsm.h"
#include "ccp.h"
#include <net/ppp_comp.h>

/*
 * 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 *, 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",
    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 void ccp_rack_timeout __P((void *));
static char *method_name __P((ccp_options *, ccp_options *));

static fsm_callbacks ccp_callbacks = {
    ccp_resetci,
    ccp_cilen,
    ccp_addci,
    ccp_ackci,
    ccp_nakci,
    ccp_rejci,
    ccp_reqci,
    ccp_up,
    ccp_down,
    NULL,
    NULL,
    NULL,
    NULL,
    ccp_extcode,
    "CCP"
};

/*
 * 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    1     /* waiting for reset-ack */
#define RREQ_REPEAT     2     /* send another reset-req if no reset-ack */

#define RACKTIMEOUT     1     /* second */

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

/*
 * 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);

    memset(&ccp_wantoptions[unit],  0, sizeof(ccp_options));
    memset(&ccp_gotoptions[unit],   0, sizeof(ccp_options));
    memset(&ccp_allowoptions[unit], 0, sizeof(ccp_options));
    memset(&ccp_hisoptions[unit],   0, 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 (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] == TERMREQ && f->state != OPENED)
      syslog(LOG_NOTICE, "Compression disabled by peer.");

    /*
     * If we get a terminate-ack and we're not asking for compression,
     * close CCP.
     */
    if (oldstate == REQSENT && p[0] == 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 (f->state != OPENED)
          break;
      /* send a reset-ack, which the transmitter will see and
         reset its compression state. */
      fsm_sdata(f, CCP_RESETACK, id, NULL, 0);
      break;

    case CCP_RESETACK:
      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:
      return 0;
    }

    return 1;
}

/*
 * ccp_protrej - peer doesn't talk CCP.
 */
static void
ccp_protrej(unit)
    int unit;
{
    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
     * compression 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);
          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);
          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? 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) {
            go->deflate = 0;
            break;
          }
          --go->deflate_size;
          p[2] = DEFLATE_MAKE_OPT(go->deflate_size);
      }
      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);
          }
      }
    }
    /* XXX Should Predictor 2 be preferable to Predictor 1? */
    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) {
      if (len < CILEN_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)
          return 0;
      p += CILEN_DEFLATE;
      len -= CILEN_DEFLATE;
      /* XXX Cope with first/fast ack */
      if (len == 0)
          return 1;
      if (go->deflate_correct && 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;
          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;
      p += CILEN_BSD_COMPRESS;
      len -= CILEN_BSD_COMPRESS;
      /* XXX Cope with first/fast ack */
      if (p == p0 && len == 0)
          return 1;
    }
    if (go->predictor_1) {
      if (len < CILEN_PREDICTOR_1
          || p[0] != CI_PREDICTOR_1 || p[1] != CILEN_PREDICTOR_1)
          return 0;
      p += CILEN_PREDICTOR_1;
      len -= CILEN_PREDICTOR_1;
      /* XXX Cope with first/fast ack */
      if (p == p0 && len == 0)
          return 1;
    }
    if (go->predictor_2) {
      if (len < CILEN_PREDICTOR_2
          || p[0] != CI_PREDICTOR_2 || p[1] != CILEN_PREDICTOR_2)
          return 0;
      p += CILEN_PREDICTOR_2;
      len -= CILEN_PREDICTOR_2;
      /* XXX Cope with first/fast ack */
      if (p == p0 && len == 0)
          return 1;
    }

    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 */

    memset(&no, 0, sizeof(no));
    try = *go;

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

    if (go->bsd_compress && len >= CILEN_BSD_COMPRESS
      && p[0] == CI_BSD_COMPRESS && p[1] == CILEN_BSD_COMPRESS) {
      no.bsd_compress = 1;
      /*
       * Peer wants us to use a different number of bits
       * or a different version.
       */
      if (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]);
      p += CILEN_BSD_COMPRESS;
      len -= CILEN_BSD_COMPRESS;
    }

    /*
     * Predictor-1 and 2 have no options, so they can't be Naked.
     *
     * XXX What should we do with any remaining options?
     */

    if (len != 0)
      return 0;

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

/*
 * ccp_rejci - reject 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 && len >= CILEN_DEFLATE
      && p[0] == (go->deflate_correct? CI_DEFLATE: 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 */
      if (go->deflate_correct)
          try.deflate_correct = 0;
      else
          try.deflate_draft = 0;
      p += CILEN_DEFLATE;
      len -= CILEN_DEFLATE;
      if (go->deflate_correct && 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 - processed a received configure-request.
 * Returns CONFACK, CONFNAK or CONFREJ and the packet 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, *retp;
    int len, clen, type, nb;
    ccp_options *ho = &ccp_hisoptions[f->unit];
    ccp_options *ao = &ccp_allowoptions[f->unit];

    ret = CONFACK;
    retp = p0 = p;
    len = *lenp;

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

    while (len > 0) {
      newret = CONFACK;
      if (len < 2 || p[1] < 2 || p[1] > len) {
          /* length is bad */
          clen = len;
          newret = CONFREJ;

      } else {
          type = p[0];
          clen = p[1];

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

            ho->deflate = 1;
            ho->deflate_size = nb = DEFLATE_SIZE(p[2]);
            if (DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL
                || p[3] != DEFLATE_CHK_SEQUENCE
                || nb > ao->deflate_size || nb < DEFLATE_MIN_SIZE) {
                newret = CONFNAK;
                if (!dont_nak) {
                  p[2] = DEFLATE_MAKE_OPT(ao->deflate_size);
                  p[3] = DEFLATE_CHK_SEQUENCE;
                  /* fall through to test this #bits below */
                } else
                  break;
            }

            /*
             * 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, p, CILEN_DEFLATE, 1);
                  if (res > 0)
                      break;        /* it's OK now */
                  if (res < 0 || nb == DEFLATE_MIN_SIZE || dont_nak) {
                      newret = CONFREJ;
                      p[2] = DEFLATE_MAKE_OPT(ho->deflate_size);
                      break;
                  }
                  newret = CONFNAK;
                  --nb;
                  p[2] = DEFLATE_MAKE_OPT(nb);
                }
            }
            break;

          case CI_BSD_COMPRESS:
            if (!ao->bsd_compress || clen != CILEN_BSD_COMPRESS) {
                newret = CONFREJ;
                break;
            }

            ho->bsd_compress = 1;
            ho->bsd_bits = nb = BSD_NBITS(p[2]);
            if (BSD_VERSION(p[2]) != BSD_CURRENT_VERSION
                || nb > ao->bsd_bits || nb < BSD_MIN_BITS) {
                newret = CONFNAK;
                if (!dont_nak) {
                  p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, ao->bsd_bits);
                  /* fall through to test this #bits below */
                } else
                  break;
            }

            /*
             * 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, p, CILEN_BSD_COMPRESS, 1);
                  if (res > 0)
                      break;
                  if (res < 0 || nb == BSD_MIN_BITS || dont_nak) {
                      newret = CONFREJ;
                      p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION,
                                    ho->bsd_bits);
                      break;
                  }
                  newret = CONFNAK;
                  --nb;
                  p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, nb);
                }
            }
            break;

          case CI_PREDICTOR_1:
            if (!ao->predictor_1 || clen != CILEN_PREDICTOR_1) {
                newret = CONFREJ;
                break;
            }

            ho->predictor_1 = 1;
            if (p == p0
                && ccp_test(f->unit, p, CILEN_PREDICTOR_1, 1) <= 0) {
                newret = CONFREJ;
            }
            break;

          case CI_PREDICTOR_2:
            if (!ao->predictor_2 || clen != CILEN_PREDICTOR_2) {
                newret = CONFREJ;
                break;
            }

            ho->predictor_2 = 1;
            if (p == p0
                && ccp_test(f->unit, p, CILEN_PREDICTOR_2, 1) <= 0) {
                newret = CONFREJ;
            }
            break;

          default:
            newret = CONFREJ;
          }
      }

      if (newret == CONFNAK && dont_nak)
          newret = CONFREJ;
      if (!(newret == CONFACK || (newret == CONFNAK && ret == CONFREJ))) {
          /* we're returning this option */
          if (newret == CONFREJ && ret == CONFNAK)
            retp = p0;
          ret = newret;
          if (p != retp)
            BCOPY(p, retp, clen);
          retp += clen;
      }

      p += clen;
      len -= clen;
    }

    if (ret != CONFACK) {
      if (ret == CONFREJ && *lenp == retp - p0)
          all_rejected[f->unit] = 1;
      else
          *lenp = retp - p0;
    }
    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)
          sprintf(result, "Deflate%s (%d/%d)",
                (opt->method == CI_DEFLATE_DRAFT? "(old#)": ""),
                opt->deflate_size, opt2->deflate_size);
      else
          sprintf(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)
          sprintf(result, "BSD-Compress (%d/%d)", opt->bsd_bits,
                opt2->bsd_bits);
      else
          sprintf(result, "BSD-Compress (%d)", opt->bsd_bits);
      break;
    case CI_PREDICTOR_1:
      return "Predictor 1";
    case CI_PREDICTOR_2:
      return "Predictor 2";
    default:
      sprintf(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];

    ccp_flags_set(f->unit, 1, 1);
    if (ANY_COMPRESS(*go)) {
      if (ANY_COMPRESS(*ho)) {
          if (go->method == ho->method) {
            syslog(LOG_NOTICE, "%s compression enabled",
                   method_name(go, ho));
          } else {
            strcpy(method1, method_name(go, NULL));
            syslog(LOG_NOTICE, "%s / %s compression enabled",
                   method1, method_name(ho, NULL));
          }
      } else
          syslog(LOG_NOTICE, "%s receive compression enabled",
               method_name(go, NULL));
    } else if (ANY_COMPRESS(*ho))
      syslog(LOG_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);
    ccp_localstate[f->unit] = 0;
    ccp_flags_set(f->unit, 1, 0);
}

/*
 * Print the contents of a CCP packet.
 */
static char *ccp_codenames[] = {
    "ConfReq", "ConfAck", "ConfNak", "ConfRej",
    "TermReq", "TermAck", "CodeRej",
    NULL, NULL, NULL, NULL, NULL, NULL,
    "ResetReq", "ResetAck",
};

static int
ccp_printpkt(p, plen, printer, arg)
    u_char *p;
    int plen;
    void (*printer) __P((void *, char *, ...));
    void *arg;
{
    u_char *p0, *optend;
    int code, id, len;
    int optlen;

    p0 = p;
    if (plen < HEADERLEN)
      return 0;
    code = p[0];
    id = p[1];
    len = (p[2] << 8) + p[3];
    if (len < HEADERLEN || len > plen)
      return 0;

    if (code >= 1 && code <= sizeof(ccp_codenames) / sizeof(char *)
      && ccp_codenames[code-1] != NULL)
      printer(arg, " %s", ccp_codenames[code-1]);
    else
      printer(arg, " code=0x%x", code);
    printer(arg, " id=0x%x", id);
    len -= HEADERLEN;
    p += HEADERLEN;

    switch (code) {
    case CONFREQ:
    case CONFACK:
    case CONFNAK:
    case CONFREJ:
      /* print list of possible compression methods */
      while (len >= 2) {
          code = p[0];
          optlen = p[1];
          if (optlen < 2 || optlen > len)
            break;
          printer(arg, " <");
          len -= optlen;
          optend = p + optlen;
          switch (code) {
          case CI_DEFLATE:
          case CI_DEFLATE_DRAFT:
            if (optlen >= CILEN_DEFLATE) {
                printer(arg, "deflate%s %d",
                      (code == CI_DEFLATE_DRAFT? "(old#)": ""),
                      DEFLATE_SIZE(p[2]));
                if (DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL)
                  printer(arg, " method %d", DEFLATE_METHOD(p[2]));
                if (p[3] != DEFLATE_CHK_SEQUENCE)
                  printer(arg, " check %d", p[3]);
                p += CILEN_DEFLATE;
            }
            break;
          case CI_BSD_COMPRESS:
            if (optlen >= CILEN_BSD_COMPRESS) {
                printer(arg, "bsd v%d %d", BSD_VERSION(p[2]),
                      BSD_NBITS(p[2]));
                p += CILEN_BSD_COMPRESS;
            }
            break;
          case CI_PREDICTOR_1:
            if (optlen >= CILEN_PREDICTOR_1) {
                printer(arg, "predictor 1");
                p += CILEN_PREDICTOR_1;
            }
            break;
          case CI_PREDICTOR_2:
            if (optlen >= CILEN_PREDICTOR_2) {
                printer(arg, "predictor 2");
                p += CILEN_PREDICTOR_2;
            }
            break;
          }
          while (p < optend)
            printer(arg, " %.2x", *p++);
          printer(arg, ">");
      }
      break;

    case TERMACK:
    case TERMREQ:
      if (len > 0 && *p >= ' ' && *p < 0x7f) {
          print_string(p, len, printer, arg);
          p += len;
          len = 0;
      }
      break;
    }

    /* dump out the rest of the packet in hex */
    while (--len >= 0)
      printer(arg, " %.2x", *p++);

    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.
 */
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.
           */
          syslog(LOG_ERR, "Lost compression sync: disabling compression");
          ccp_close(unit, "Lost compression sync");
      } else {
          /*
           * Send a reset-request to reset the peer's compressor.
           * We don't do that if we are still waiting for an
           * acknowledgement to a previous reset-request.
           */
          if (!(ccp_localstate[f->unit] & RACK_PENDING)) {
            fsm_sdata(f, CCP_RESETREQ, f->reqid = ++f->id, NULL, 0);
            TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
            ccp_localstate[f->unit] |= RACK_PENDING;
          } else
            ccp_localstate[f->unit] |= RREQ_REPEAT;
      }
    }
}

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

    if (f->state == OPENED && ccp_localstate[f->unit] & RREQ_REPEAT) {
      fsm_sdata(f, CCP_RESETREQ, f->reqid, NULL, 0);
      TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
      ccp_localstate[f->unit] &= ~RREQ_REPEAT;
    } else
      ccp_localstate[f->unit] &= ~RACK_PENDING;
}


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