usr.sbin/pppd/chap.c

   1 /*
   2  * chap.c - Challenge Handshake Authentication Protocol.
   3  *
   4  * Copyright (c) 1993 The Australian National University.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms are permitted
   8  * provided that the above copyright notice and this paragraph are
   9  * duplicated in all such forms and that any documentation,
  10  * advertising materials, and other materials related to such
  11  * distribution and use acknowledge that the software was developed
  12  * by the Australian National University.  The name of the University
  13  * may not be used to endorse or promote products derived from this
  14  * software without specific prior written permission.
  15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  17  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  18  *
  19  * Copyright (c) 1991 Gregory M. Christy.
  20  * All rights reserved.
  21  *
  22  * Redistribution and use in source and binary forms are permitted
  23  * provided that the above copyright notice and this paragraph are
  24  * duplicated in all such forms and that any documentation,
  25  * advertising materials, and other materials related to such
  26  * distribution and use acknowledge that the software was developed
  27  * by Gregory M. Christy.  The name of the author may not be used to
  28  * endorse or promote products derived from this software without
  29  * specific prior written permission.
  30  *
  31  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  33  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  34  *
  35  * $FreeBSD: src/usr.sbin/pppd/chap.c,v 1.10 1999/08/28 01:19:01 peter Exp $
  36  * $DragonFly: src/usr.sbin/pppd/chap.c,v 1.4 2005/11/24 23:42:54 swildner Exp $
  37  */
  38
  39 /*
  40  * TODO:
  41  */
  42
  43 #include <stdio.h>
  44 #include <string.h>
  45 #include <sys/types.h>
  46 #include <sys/time.h>
  47 #include <syslog.h>
  48 #include <md5.h>
  49
  50 #include "pppd.h"
  51 #include "chap.h"
  52 #include "md5.h"
  53 #ifdef CHAPMS
  54 #include "chap_ms.h"
  55 #endif
  56
  57 /*
  58  * Protocol entry points.
  59  */
  60 static void ChapInit(int);
  61 static void ChapLowerUp(int);
  62 static void ChapLowerDown(int);
  63 static void ChapInput(int, u_char *, int);
  64 static void ChapProtocolReject(int);
  65 static int  ChapPrintPkt(u_char *, int,
  66                               void (*)(void *, char *, ...), void *);
  67
  68 struct protent chap_protent = {
  69     PPP_CHAP,
  70     ChapInit,
  71     ChapInput,
  72     ChapProtocolReject,
  73     ChapLowerUp,
  74     ChapLowerDown,
  75     NULL,
  76     NULL,
  77     ChapPrintPkt,
  78     NULL,
  79     1,
  80     "CHAP",
  81     NULL,
  82     NULL,
  83     NULL
  84 };
  85
  86 chap_state chap[NUM_PPP];               /* CHAP state; one for each unit */
  87
  88 static void ChapChallengeTimeout(void *);
  89 static void ChapResponseTimeout(void *);
  90 static void ChapReceiveChallenge(chap_state *, u_char *, int, int);
  91 static void ChapRechallenge(void *);
  92 static void ChapReceiveResponse(chap_state *, u_char *, int, int);
  93 static void ChapReceiveSuccess(chap_state *, u_char *, int, int);
  94 static void ChapReceiveFailure(chap_state *, u_char *, int, int);
  95 static void ChapSendStatus(chap_state *, int);
  96 static void ChapSendChallenge(chap_state *);
  97 static void ChapSendResponse(chap_state *);
  98 static void ChapGenChallenge(chap_state *);
  99
 100 extern double drand48(void);
 101 extern void srand48(long);
 102
 103 /*
 104  * ChapInit - Initialize a CHAP unit.
 105  */
 106 static void
 107 ChapInit(int unit)
 108 {
 109     chap_state *cstate = &chap[unit];
 110
 111     BZERO(cstate, sizeof(*cstate));
 112     cstate->unit = unit;
 113     cstate->clientstate = CHAPCS_INITIAL;
 114     cstate->serverstate = CHAPSS_INITIAL;
 115     cstate->timeouttime = CHAP_DEFTIMEOUT;
 116     cstate->max_transmits = CHAP_DEFTRANSMITS;
 117     /* random number generator is initialized in magic_init */
 118 }
 119
 120
 121 /*
 122  * ChapAuthWithPeer - Authenticate us with our peer (start client).
 123  *
 124  */
 125 void
 126 ChapAuthWithPeer(int unit, char *our_name, int digest)
 127 {
 128     chap_state *cstate = &chap[unit];
 129
 130     cstate->resp_name = our_name;
 131     cstate->resp_type = digest;
 132
 133     if (cstate->clientstate == CHAPCS_INITIAL ||
 134         cstate->clientstate == CHAPCS_PENDING) {
 135         /* lower layer isn't up - wait until later */
 136         cstate->clientstate = CHAPCS_PENDING;
 137         return;
 138     }
 139
 140     /*
 141      * We get here as a result of LCP coming up.
 142      * So even if CHAP was open before, we will
 143      * have to re-authenticate ourselves.
 144      */
 145     cstate->clientstate = CHAPCS_LISTEN;
 146 }
 147
 148
 149 /*
 150  * ChapAuthPeer - Authenticate our peer (start server).
 151  */
 152 void
 153 ChapAuthPeer(int unit, char *our_name, int digest)
 154 {
 155     chap_state *cstate = &chap[unit];
 156
 157     cstate->chal_name = our_name;
 158     cstate->chal_type = digest;
 159
 160     if (cstate->serverstate == CHAPSS_INITIAL ||
 161         cstate->serverstate == CHAPSS_PENDING) {
 162         /* lower layer isn't up - wait until later */
 163         cstate->serverstate = CHAPSS_PENDING;
 164         return;
 165     }
 166
 167     ChapGenChallenge(cstate);
 168     ChapSendChallenge(cstate);          /* crank it up dude! */
 169     cstate->serverstate = CHAPSS_INITIAL_CHAL;
 170 }
 171
 172
 173 /*
 174  * ChapChallengeTimeout - Timeout expired on sending challenge.
 175  */
 176 static void
 177 ChapChallengeTimeout(void *arg)
 178 {
 179     chap_state *cstate = (chap_state *) arg;
 180
 181     /* if we aren't sending challenges, don't worry.  then again we */
 182     /* probably shouldn't be here either */
 183     if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
 184         cstate->serverstate != CHAPSS_RECHALLENGE)
 185         return;
 186
 187     if (cstate->chal_transmits >= cstate->max_transmits) {
 188         /* give up on peer */
 189         syslog(LOG_ERR, "Peer failed to respond to CHAP challenge");
 190         cstate->serverstate = CHAPSS_BADAUTH;
 191         auth_peer_fail(cstate->unit, PPP_CHAP);
 192         return;
 193     }
 194
 195     ChapSendChallenge(cstate);          /* Re-send challenge */
 196 }
 197
 198
 199 /*
 200  * ChapResponseTimeout - Timeout expired on sending response.
 201  */
 202 static void
 203 ChapResponseTimeout(void *arg)
 204 {
 205     chap_state *cstate = (chap_state *) arg;
 206
 207     /* if we aren't sending a response, don't worry. */
 208     if (cstate->clientstate != CHAPCS_RESPONSE)
 209         return;
 210
 211     ChapSendResponse(cstate);           /* re-send response */
 212 }
 213
 214
 215 /*
 216  * ChapRechallenge - Time to challenge the peer again.
 217  */
 218 static void
 219 ChapRechallenge(void *arg)
 220 {
 221     chap_state *cstate = (chap_state *) arg;
 222
 223     /* if we aren't sending a response, don't worry. */
 224     if (cstate->serverstate != CHAPSS_OPEN)
 225         return;
 226
 227     ChapGenChallenge(cstate);
 228     ChapSendChallenge(cstate);
 229     cstate->serverstate = CHAPSS_RECHALLENGE;
 230 }
 231
 232
 233 /*
 234  * ChapLowerUp - The lower layer is up.
 235  *
 236  * Start up if we have pending requests.
 237  */
 238 static void
 239 ChapLowerUp(int unit)
 240 {
 241     chap_state *cstate = &chap[unit];
 242
 243     if (cstate->clientstate == CHAPCS_INITIAL)
 244         cstate->clientstate = CHAPCS_CLOSED;
 245     else if (cstate->clientstate == CHAPCS_PENDING)
 246         cstate->clientstate = CHAPCS_LISTEN;
 247
 248     if (cstate->serverstate == CHAPSS_INITIAL)
 249         cstate->serverstate = CHAPSS_CLOSED;
 250     else if (cstate->serverstate == CHAPSS_PENDING) {
 251         ChapGenChallenge(cstate);
 252         ChapSendChallenge(cstate);
 253         cstate->serverstate = CHAPSS_INITIAL_CHAL;
 254     }
 255 }
 256
 257
 258 /*
 259  * ChapLowerDown - The lower layer is down.
 260  *
 261  * Cancel all timeouts.
 262  */
 263 static void
 264 ChapLowerDown(int unit)
 265 {
 266     chap_state *cstate = &chap[unit];
 267
 268     /* Timeout(s) pending?  Cancel if so. */
 269     if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
 270         cstate->serverstate == CHAPSS_RECHALLENGE)
 271         UNTIMEOUT(ChapChallengeTimeout, cstate);
 272     else if (cstate->serverstate == CHAPSS_OPEN
 273              && cstate->chal_interval != 0)
 274         UNTIMEOUT(ChapRechallenge, cstate);
 275     if (cstate->clientstate == CHAPCS_RESPONSE)
 276         UNTIMEOUT(ChapResponseTimeout, cstate);
 277
 278     cstate->clientstate = CHAPCS_INITIAL;
 279     cstate->serverstate = CHAPSS_INITIAL;
 280 }
 281
 282
 283 /*
 284  * ChapProtocolReject - Peer doesn't grok CHAP.
 285  */
 286 static void
 287 ChapProtocolReject(int unit)
 288 {
 289     chap_state *cstate = &chap[unit];
 290
 291     if (cstate->serverstate != CHAPSS_INITIAL &&
 292         cstate->serverstate != CHAPSS_CLOSED)
 293         auth_peer_fail(unit, PPP_CHAP);
 294     if (cstate->clientstate != CHAPCS_INITIAL &&
 295         cstate->clientstate != CHAPCS_CLOSED)
 296         auth_withpeer_fail(unit, PPP_CHAP);
 297     ChapLowerDown(unit);                /* shutdown chap */
 298 }
 299
 300
 301 /*
 302  * ChapInput - Input CHAP packet.
 303  */
 304 static void
 305 ChapInput(int unit, u_char *inpacket, int packet_len)
 306 {
 307     chap_state *cstate = &chap[unit];
 308     u_char *inp;
 309     u_char code, id;
 310     int len;
 311
 312     /*
 313      * Parse header (code, id and length).
 314      * If packet too short, drop it.
 315      */
 316     inp = inpacket;
 317     if (packet_len < CHAP_HEADERLEN) {
 318         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short header."));
 319         return;
 320     }
 321     GETCHAR(code, inp);
 322     GETCHAR(id, inp);
 323     GETSHORT(len, inp);
 324     if (len < CHAP_HEADERLEN) {
 325         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd illegal length."));
 326         return;
 327     }
 328     if (len > packet_len) {
 329         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short packet."));
 330         return;
 331     }
 332     len -= CHAP_HEADERLEN;
 333
 334     /*
 335      * Action depends on code (as in fact it usually does :-).
 336      */
 337     switch (code) {
 338     case CHAP_CHALLENGE:
 339         ChapReceiveChallenge(cstate, inp, id, len);
 340         break;
 341
 342     case CHAP_RESPONSE:
 343         ChapReceiveResponse(cstate, inp, id, len);
 344         break;
 345
 346     case CHAP_FAILURE:
 347         ChapReceiveFailure(cstate, inp, id, len);
 348         break;
 349
 350     case CHAP_SUCCESS:
 351         ChapReceiveSuccess(cstate, inp, id, len);
 352         break;
 353
 354     default:                            /* Need code reject? */
 355         syslog(LOG_WARNING, "Unknown CHAP code (%d) received.", code);
 356         break;
 357     }
 358 }
 359
 360
 361 /*
 362  * ChapReceiveChallenge - Receive Challenge and send Response.
 363  */
 364 static void
 365 ChapReceiveChallenge(chap_state *cstate, u_char *inp, int id, int len)
 366 {
 367     int rchallenge_len;
 368     u_char *rchallenge;
 369     int secret_len;
 370     char secret[MAXSECRETLEN];
 371     char rhostname[256];
 372     MD5_CTX mdContext;
 373     u_char hash[MD5_SIGNATURE_SIZE];
 374
 375     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: Rcvd id %d.", id));
 376     if (cstate->clientstate == CHAPCS_CLOSED ||
 377         cstate->clientstate == CHAPCS_PENDING) {
 378         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: in state %d",
 379                    cstate->clientstate));
 380         return;
 381     }
 382
 383     if (len < 2) {
 384         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 385         return;
 386     }
 387
 388     GETCHAR(rchallenge_len, inp);
 389     len -= sizeof (u_char) + rchallenge_len;    /* now name field length */
 390     if (len < 0) {
 391         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 392         return;
 393     }
 394     rchallenge = inp;
 395     INCPTR(rchallenge_len, inp);
 396
 397     if (len >= sizeof(rhostname))
 398         len = sizeof(rhostname) - 1;
 399     BCOPY(inp, rhostname, len);
 400     rhostname[len] = '\000';
 401
 402     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: received name field '%s'",
 403                rhostname));
 404
 405     /* Microsoft doesn't send their name back in the PPP packet */
 406     if (remote_name[0] != 0 && (explicit_remote || rhostname[0] == 0)) {
 407         strncpy(rhostname, remote_name, sizeof(rhostname));
 408         rhostname[sizeof(rhostname) - 1] = 0;
 409         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: using '%s' as remote name",
 410                    rhostname));
 411     }
 412
 413     /* get secret for authenticating ourselves with the specified host */
 414     if (!get_secret(cstate->unit, cstate->resp_name, rhostname,
 415                     secret, &secret_len, 0)) {
 416         secret_len = 0;         /* assume null secret if can't find one */
 417         syslog(LOG_WARNING, "No CHAP secret found for authenticating us to %s",
 418                rhostname);
 419     }
 420
 421     /* cancel response send timeout if necessary */
 422     if (cstate->clientstate == CHAPCS_RESPONSE)
 423         UNTIMEOUT(ChapResponseTimeout, cstate);
 424
 425     cstate->resp_id = id;
 426     cstate->resp_transmits = 0;
 427
 428     /*  generate MD based on negotiated type */
 429     switch (cstate->resp_type) {
 430
 431     case CHAP_DIGEST_MD5:
 432         MD5Init(&mdContext);
 433         MD5Update(&mdContext, &cstate->resp_id, 1);
 434         MD5Update(&mdContext, secret, secret_len);
 435         MD5Update(&mdContext, rchallenge, rchallenge_len);
 436         MD5Final(hash, &mdContext);
 437         BCOPY(hash, cstate->response, MD5_SIGNATURE_SIZE);
 438         cstate->resp_length = MD5_SIGNATURE_SIZE;
 439         break;
 440
 441 #ifdef CHAPMS
 442     case CHAP_MICROSOFT:
 443         ChapMS(cstate, rchallenge, rchallenge_len, secret, secret_len);
 444         break;
 445 #endif
 446
 447     default:
 448         CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->resp_type));
 449         return;
 450     }
 451
 452     BZERO(secret, sizeof(secret));
 453     ChapSendResponse(cstate);
 454 }
 455
 456
 457 /*
 458  * ChapReceiveResponse - Receive and process response.
 459  */
 460 static void
 461 ChapReceiveResponse(chap_state *cstate, u_char *inp, int id, int len)
 462 {
 463     u_char *remmd, remmd_len;
 464     int secret_len, old_state;
 465     int code;
 466     char rhostname[256];
 467     MD5_CTX mdContext;
 468     char secret[MAXSECRETLEN];
 469     u_char hash[MD5_SIGNATURE_SIZE];
 470
 471     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: Rcvd id %d.", id));
 472
 473     if (cstate->serverstate == CHAPSS_CLOSED ||
 474         cstate->serverstate == CHAPSS_PENDING) {
 475         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: in state %d",
 476                    cstate->serverstate));
 477         return;
 478     }
 479
 480     if (id != cstate->chal_id)
 481         return;                 /* doesn't match ID of last challenge */
 482
 483     /*
 484      * If we have received a duplicate or bogus Response,
 485      * we have to send the same answer (Success/Failure)
 486      * as we did for the first Response we saw.
 487      */
 488     if (cstate->serverstate == CHAPSS_OPEN) {
 489         ChapSendStatus(cstate, CHAP_SUCCESS);
 490         return;
 491     }
 492     if (cstate->serverstate == CHAPSS_BADAUTH) {
 493         ChapSendStatus(cstate, CHAP_FAILURE);
 494         return;
 495     }
 496
 497     if (len < 2) {
 498         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 499         return;
 500     }
 501     GETCHAR(remmd_len, inp);            /* get length of MD */
 502     remmd = inp;                        /* get pointer to MD */
 503     INCPTR(remmd_len, inp);
 504
 505     len -= sizeof (u_char) + remmd_len;
 506     if (len < 0) {
 507         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 508         return;
 509     }
 510
 511     UNTIMEOUT(ChapChallengeTimeout, cstate);
 512
 513     if (len >= sizeof(rhostname))
 514         len = sizeof(rhostname) - 1;
 515     BCOPY(inp, rhostname, len);
 516     rhostname[len] = '\000';
 517
 518     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: received name field: %s",
 519                rhostname));
 520
 521     /*
 522      * Get secret for authenticating them with us,
 523      * do the hash ourselves, and compare the result.
 524      */
 525     code = CHAP_FAILURE;
 526     if (!get_secret(cstate->unit, rhostname, cstate->chal_name,
 527                    secret, &secret_len, 1)) {
 528         syslog(LOG_WARNING, "No CHAP secret found for authenticating %s",
 529                rhostname);
 530     } else {
 531
 532         /*  generate MD based on negotiated type */
 533         switch (cstate->chal_type) {
 534
 535         case CHAP_DIGEST_MD5:           /* only MD5 is defined for now */
 536             if (remmd_len != MD5_SIGNATURE_SIZE)
 537                 break;                  /* it's not even the right length */
 538             MD5Init(&mdContext);
 539             MD5Update(&mdContext, &cstate->chal_id, 1);
 540             MD5Update(&mdContext, secret, secret_len);
 541             MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
 542             MD5Final(hash, &mdContext);
 543
 544             /* compare local and remote MDs and send the appropriate status */
 545             if (memcmp (hash, remmd, MD5_SIGNATURE_SIZE) == 0)
 546                 code = CHAP_SUCCESS;    /* they are the same! */
 547             break;
 548
 549         default:
 550             CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->chal_type));
 551         }
 552     }
 553
 554     BZERO(secret, sizeof(secret));
 555     ChapSendStatus(cstate, code);
 556
 557     if (code == CHAP_SUCCESS) {
 558         old_state = cstate->serverstate;
 559         cstate->serverstate = CHAPSS_OPEN;
 560         if (old_state == CHAPSS_INITIAL_CHAL) {
 561             auth_peer_success(cstate->unit, PPP_CHAP, rhostname, len);
 562         }
 563         if (cstate->chal_interval != 0)
 564             TIMEOUT(ChapRechallenge, cstate, cstate->chal_interval);
 565         syslog(LOG_NOTICE, "CHAP peer authentication succeeded for %s",
 566                rhostname);
 567
 568     } else {
 569         syslog(LOG_ERR, "CHAP peer authentication failed for remote host %s",
 570                rhostname);
 571         cstate->serverstate = CHAPSS_BADAUTH;
 572         auth_peer_fail(cstate->unit, PPP_CHAP);
 573     }
 574 }
 575
 576 /*
 577  * ChapReceiveSuccess - Receive Success
 578  */
 579 static void
 580 ChapReceiveSuccess(chap_state *cstate, u_char *inp, int id, int len)
 581 {
 582
 583     CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: Rcvd id %d.", id));
 584
 585     if (cstate->clientstate == CHAPCS_OPEN)
 586         /* presumably an answer to a duplicate response */
 587         return;
 588
 589     if (cstate->clientstate != CHAPCS_RESPONSE) {
 590         /* don't know what this is */
 591         CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: in state %d\n",
 592                    cstate->clientstate));
 593         return;
 594     }
 595
 596     UNTIMEOUT(ChapResponseTimeout, cstate);
 597
 598     /*
 599      * Print message.
 600      */
 601     if (len > 0)
 602         PRINTMSG(inp, len);
 603
 604     cstate->clientstate = CHAPCS_OPEN;
 605
 606     auth_withpeer_success(cstate->unit, PPP_CHAP);
 607 }
 608
 609
 610 /*
 611  * ChapReceiveFailure - Receive failure.
 612  */
 613 static void
 614 ChapReceiveFailure(chap_state *cstate, u_char *inp, int id, int len)
 615 {
 616     CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: Rcvd id %d.", id));
 617
 618     if (cstate->clientstate != CHAPCS_RESPONSE) {
 619         /* don't know what this is */
 620         CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: in state %d\n",
 621                    cstate->clientstate));
 622         return;
 623     }
 624
 625     UNTIMEOUT(ChapResponseTimeout, cstate);
 626
 627     /*
 628      * Print message.
 629      */
 630     if (len > 0)
 631         PRINTMSG(inp, len);
 632
 633     syslog(LOG_ERR, "CHAP authentication failed");
 634     auth_withpeer_fail(cstate->unit, PPP_CHAP);
 635 }
 636
 637
 638 /*
 639  * ChapSendChallenge - Send an Authenticate challenge.
 640  */
 641 static void
 642 ChapSendChallenge(chap_state *cstate)
 643 {
 644     u_char *outp;
 645     int chal_len, name_len;
 646     int outlen;
 647
 648     chal_len = cstate->chal_len;
 649     name_len = strlen(cstate->chal_name);
 650     outlen = CHAP_HEADERLEN + sizeof (u_char) + chal_len + name_len;
 651     outp = outpacket_buf;
 652
 653     MAKEHEADER(outp, PPP_CHAP);         /* paste in a CHAP header */
 654
 655     PUTCHAR(CHAP_CHALLENGE, outp);
 656     PUTCHAR(cstate->chal_id, outp);
 657     PUTSHORT(outlen, outp);
 658
 659     PUTCHAR(chal_len, outp);            /* put length of challenge */
 660     BCOPY(cstate->challenge, outp, chal_len);
 661     INCPTR(chal_len, outp);
 662
 663     BCOPY(cstate->chal_name, outp, name_len);   /* append hostname */
 664
 665     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 666
 667     CHAPDEBUG((LOG_INFO, "ChapSendChallenge: Sent id %d.", cstate->chal_id));
 668
 669     TIMEOUT(ChapChallengeTimeout, cstate, cstate->timeouttime);
 670     ++cstate->chal_transmits;
 671 }
 672
 673
 674 /*
 675  * ChapSendStatus - Send a status response (ack or nak).
 676  */
 677 static void
 678 ChapSendStatus(chap_state *cstate, int code)
 679 {
 680     u_char *outp;
 681     int outlen, msglen;
 682     char msg[256];
 683
 684     if (code == CHAP_SUCCESS)
 685         sprintf(msg, "Welcome to %s.", hostname);
 686     else
 687         sprintf(msg, "I don't like you.  Go 'way.");
 688     msglen = strlen(msg);
 689
 690     outlen = CHAP_HEADERLEN + msglen;
 691     outp = outpacket_buf;
 692
 693     MAKEHEADER(outp, PPP_CHAP); /* paste in a header */
 694
 695     PUTCHAR(code, outp);
 696     PUTCHAR(cstate->chal_id, outp);
 697     PUTSHORT(outlen, outp);
 698     BCOPY(msg, outp, msglen);
 699     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 700
 701     CHAPDEBUG((LOG_INFO, "ChapSendStatus: Sent code %d, id %d.", code,
 702                cstate->chal_id));
 703 }
 704
 705 /*
 706  * ChapGenChallenge is used to generate a pseudo-random challenge string of
 707  * a pseudo-random length between min_len and max_len.  The challenge
 708  * string and its length are stored in *cstate, and various other fields of
 709  * *cstate are initialized.
 710  */
 711
 712 static void
 713 ChapGenChallenge(chap_state *cstate)
 714 {
 715     int chal_len;
 716     u_char *ptr = cstate->challenge;
 717     unsigned int i;
 718
 719     /* pick a random challenge length between MIN_CHALLENGE_LENGTH and
 720        MAX_CHALLENGE_LENGTH */
 721     chal_len =  (unsigned) ((drand48() *
 722                              (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
 723                             MIN_CHALLENGE_LENGTH);
 724     cstate->chal_len = chal_len;
 725     cstate->chal_id = ++cstate->id;
 726     cstate->chal_transmits = 0;
 727
 728     /* generate a random string */
 729     for (i = 0; i < chal_len; i++ )
 730         *ptr++ = (char) (drand48() * 0xff);
 731 }
 732
 733 /*
 734  * ChapSendResponse - send a response packet with values as specified
 735  * in *cstate.
 736  */
 737 /* ARGSUSED */
 738 static void
 739 ChapSendResponse(chap_state *cstate)
 740 {
 741     u_char *outp;
 742     int outlen, md_len, name_len;
 743
 744     md_len = cstate->resp_length;
 745     name_len = strlen(cstate->resp_name);
 746     outlen = CHAP_HEADERLEN + sizeof (u_char) + md_len + name_len;
 747     outp = outpacket_buf;
 748
 749     MAKEHEADER(outp, PPP_CHAP);
 750
 751     PUTCHAR(CHAP_RESPONSE, outp);       /* we are a response */
 752     PUTCHAR(cstate->resp_id, outp);     /* copy id from challenge packet */
 753     PUTSHORT(outlen, outp);             /* packet length */
 754
 755     PUTCHAR(md_len, outp);              /* length of MD */
 756     BCOPY(cstate->response, outp, md_len);      /* copy MD to buffer */
 757     INCPTR(md_len, outp);
 758
 759     BCOPY(cstate->resp_name, outp, name_len); /* append our name */
 760
 761     /* send the packet */
 762     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 763
 764     cstate->clientstate = CHAPCS_RESPONSE;
 765     TIMEOUT(ChapResponseTimeout, cstate, cstate->timeouttime);
 766     ++cstate->resp_transmits;
 767 }
 768
 769 /*
 770  * ChapPrintPkt - print the contents of a CHAP packet.
 771  */
 772 static char *ChapCodenames[] = {
 773     "Challenge", "Response", "Success", "Failure"
 774 };
 775
 776 static int
 777 ChapPrintPkt(u_char *p, int plen, void (*printer)(void *, char *, ...),
 778              void *arg)
 779 {
 780     int code, id, len;
 781     int clen, nlen;
 782     u_char x;
 783
 784     if (plen < CHAP_HEADERLEN)
 785         return 0;
 786     GETCHAR(code, p);
 787     GETCHAR(id, p);
 788     GETSHORT(len, p);
 789     if (len < CHAP_HEADERLEN || len > plen)
 790         return 0;
 791
 792     if (code >= 1 && code <= sizeof(ChapCodenames) / sizeof(char *))
 793         printer(arg, " %s", ChapCodenames[code-1]);
 794     else
 795         printer(arg, " code=0x%x", code);
 796     printer(arg, " id=0x%x", id);
 797     len -= CHAP_HEADERLEN;
 798     switch (code) {
 799     case CHAP_CHALLENGE:
 800     case CHAP_RESPONSE:
 801         if (len < 1)
 802             break;
 803         clen = p[0];
 804         if (len < clen + 1)
 805             break;
 806         ++p;
 807         nlen = len - clen - 1;
 808         printer(arg, " <");
 809         for (; clen > 0; --clen) {
 810             GETCHAR(x, p);
 811             printer(arg, "%.2x", x);
 812         }
 813         printer(arg, ">, name = ");
 814         print_string((char *)p, nlen, printer, arg);
 815         break;
 816     case CHAP_FAILURE:
 817     case CHAP_SUCCESS:
 818         printer(arg, " ");
 819         print_string((char *)p, len, printer, arg);
 820         break;
 821     default:
 822         for (clen = len; clen > 0; --clen) {
 823             GETCHAR(x, p);
 824             printer(arg, " %.2x", x);
 825         }
 826     }
 827
 828     return len + CHAP_HEADERLEN;
 829 }