ccp.c

自己精简过的PPPD代码。在嵌入中应用可以更好的发挥。比原先的小了很多

/*
 * ccp.c - PPP Compression Control Protocol.
 *
 * Copyright (c) 1994-2002 Paul Mackerras. 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. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <[e-mail]>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS 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.
 */

#define RCSID	"$Id: ccp.c,v 1.50 2005/06/26 19:34:41 carlsonj Exp $"

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

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

#ifdef MPPE
#include "chap_ms.h"	/* mppe_xxxx_key, mppe_keys_set */
#include "lcp.h"	/* lcp_close(), lcp_fsm */
#endif

static const char rcsid[] = RCSID;

/*
 * Unfortunately there is a bug in zlib which means that using a
 * size of 8 (window size = 256) for Deflate compression will cause
 * buffer overruns and kernel crashes in the deflate module.
 * Until this is fixed we only accept sizes in the range 9 .. 15.
 * Thanks to James Carlson for pointing this out.
 */
#define DEFLATE_MIN_WORKS	9

/*
 * Command-line options.
 */
static int setbsdcomp __P((char **));
static int setdeflate __P((char **));
static char bsd_value[8];
static char deflate_value[8];

/*
 * Option variables.
 */
#ifdef MPPE
bool refuse_mppe_stateful = 1;		/* Allow stateful mode? */
#endif

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", OPT_ALIAS },

    { "bsdcomp", o_special, (void *)setbsdcomp,
      "Request BSD-Compress packet compression",
      OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, bsd_value },
    { "nobsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
      "don't allow BSD-Compress", OPT_PRIOSUB | OPT_A2CLR,
      &ccp_allowoptions[0].bsd_compress },
    { "-bsdcomp", o_bool, &ccp_wantoptions[0].bsd_compress,
      "don't allow BSD-Compress", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
      &ccp_allowoptions[0].bsd_compress },

    { "deflate", o_special, (void *)setdeflate,
      "request Deflate compression",
      OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, deflate_value },
    { "nodeflate", o_bool, &ccp_wantoptions[0].deflate,
      "don't allow Deflate compression", OPT_PRIOSUB | OPT_A2CLR,
      &ccp_allowoptions[0].deflate },
    { "-deflate", o_bool, &ccp_wantoptions[0].deflate,
      "don't allow Deflate compression", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
      &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", OPT_PRIO | 1 },
    { "nopredictor1", o_bool, &ccp_wantoptions[0].predictor_1,
      "don't allow Predictor-1", OPT_PRIOSUB | OPT_A2CLR,
      &ccp_allowoptions[0].predictor_1 },
    { "-predictor1", o_bool, &ccp_wantoptions[0].predictor_1,
      "don't allow Predictor-1", OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLR,
      &ccp_allowoptions[0].predictor_1 },

#ifdef MPPE
    /* MPPE options are symmetrical ... we only set wantoptions here */
    { "require-mppe", o_bool, &ccp_wantoptions[0].mppe,
      "require MPPE encryption",
      OPT_PRIO | MPPE_OPT_40 | MPPE_OPT_128 },
    { "+mppe", o_bool, &ccp_wantoptions[0].mppe,
      "require MPPE encryption",
      OPT_ALIAS | OPT_PRIO | MPPE_OPT_40 | MPPE_OPT_128 },
    { "nomppe", o_bool, &ccp_wantoptions[0].mppe,
      "don't allow MPPE encryption", OPT_PRIO },
    { "-mppe", o_bool, &ccp_wantoptions[0].mppe,
      "don't allow MPPE encryption", OPT_ALIAS | OPT_PRIO },

    /* We use ccp_allowoptions[0].mppe as a junk var ... it is reset later */
    { "require-mppe-40", o_bool, &ccp_allowoptions[0].mppe,
      "require MPPE 40-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_40,
      &ccp_wantoptions[0].mppe },
    { "+mppe-40", o_bool, &ccp_allowoptions[0].mppe,
      "require MPPE 40-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_40,
      &ccp_wantoptions[0].mppe },
    { "nomppe-40", o_bool, &ccp_allowoptions[0].mppe,
      "don't allow MPPE 40-bit encryption",
      OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_40, &ccp_wantoptions[0].mppe },
    { "-mppe-40", o_bool, &ccp_allowoptions[0].mppe,
      "don't allow MPPE 40-bit encryption",
      OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_40,
      &ccp_wantoptions[0].mppe },

    { "require-mppe-128", o_bool, &ccp_allowoptions[0].mppe,
      "require MPPE 128-bit encryption", OPT_PRIO | OPT_A2OR | MPPE_OPT_128,
      &ccp_wantoptions[0].mppe },
    { "+mppe-128", o_bool, &ccp_allowoptions[0].mppe,
      "require MPPE 128-bit encryption",
      OPT_ALIAS | OPT_PRIO | OPT_A2OR | MPPE_OPT_128,
      &ccp_wantoptions[0].mppe },
    { "nomppe-128", o_bool, &ccp_allowoptions[0].mppe,
      "don't allow MPPE 128-bit encryption",
      OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_128, &ccp_wantoptions[0].mppe },
    { "-mppe-128", o_bool, &ccp_allowoptions[0].mppe,
      "don't allow MPPE 128-bit encryption",
      OPT_ALIAS | OPT_PRIOSUB | OPT_A2CLRB | MPPE_OPT_128,
      &ccp_wantoptions[0].mppe },

    /* strange one; we always request stateless, but will we allow stateful? */
    { "mppe-stateful", o_bool, &refuse_mppe_stateful,
      "allow MPPE stateful mode", OPT_PRIO },
    { "nomppe-stateful", o_bool, &refuse_mppe_stateful,
      "disallow MPPE stateful mode", OPT_PRIO | 1 },
#endif /* MPPE */

    { 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 *, 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, 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 \
				 || (opt).mppe)

/*
 * 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 */

/*
 * Option parsing.
 */
static int
setbsdcomp(argv)
    char **argv;
{
    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;
    slprintf(bsd_value, sizeof(bsd_value),
	     rbits == abits? "%d": "%d,%d", rbits, abits);

    return 1;
}

static int
setdeflate(argv)
    char **argv;
{
    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 deflate option", *argv);
	return 0;
    }
    if ((rbits != 0 && (rbits < DEFLATE_MIN_SIZE || rbits > DEFLATE_MAX_SIZE))
	|| (abits != 0 && (abits < DEFLATE_MIN_SIZE
			  || abits > DEFLATE_MAX_SIZE))) {
	option_error("deflate option values must be 0 or %d .. %d",
		     DEFLATE_MIN_SIZE, DEFLATE_MAX_SIZE);
	return 0;
    }
    if (rbits == DEFLATE_MIN_SIZE || abits == DEFLATE_MIN_SIZE) {
	if (rbits == DEFLATE_MIN_SIZE)
	    rbits = DEFLATE_MIN_WORKS;
	if (abits == DEFLATE_MIN_SIZE)
	    abits = DEFLATE_MIN_WORKS;
	warn("deflate option value of %d changed to %d to avoid zlib bug",
	     DEFLATE_MIN_SIZE, DEFLATE_MIN_WORKS);
    }
    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;
    slprintf(deflate_value, sizeof(deflate_value),
	     rbits == abits? "%d": "%d,%d", rbits, abits);

    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);

    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) {
	notice("Compression disabled by peer.");
#ifdef MPPE
	if (ccp_gotoptions[unit].mppe) {
	    error("MPPE disabled, closing LCP");
	    lcp_close(unit, "MPPE disabled by peer");
	}
#endif
    }

    /*
     * 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]);

#ifdef MPPE
    if (ccp_gotoptions[unit].mppe) {
	error("MPPE required but peer negotiation failed");
	lcp_close(unit, "MPPE required but peer negotiation failed");
    }
#endif

}

/*
 * 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[CCP_MAX_OPTION_LENGTH];

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

#ifdef MPPE
    if (go->mppe) {
	ccp_options *ao = &ccp_allowoptions[f->unit];
	int auth_mschap_bits = auth_done[f->unit];
	int numbits;

	/*
	 * Start with a basic sanity check: mschap[v2] auth must be in
	 * exactly one direction.  RFC 3079 says that the keys are
	 * 'derived from the credentials of the peer that initiated the call',
	 * however the PPP protocol doesn't have such a concept, and pppd
	 * cannot get this info externally.  Instead we do the best we can.
	 * NB: If MPPE is required, all other compression opts are invalid.
	 *     So, we return right away if we can't do it.
	 */

	/* Leave only the mschap auth bits set */
	auth_mschap_bits &= (CHAP_MS_WITHPEER  | CHAP_MS_PEER |
			     CHAP_MS2_WITHPEER | CHAP_MS2_PEER);
	/* Count the mschap auths */
	auth_mschap_bits >>= CHAP_MS_SHIFT;
	numbits = 0;