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
  36 #ifndef lint
  37 static char rcsid[] = "$Id: chap.c,v 1.14 1997/04/30 05:51:08 paulus Exp $";
  38 #endif
  39
  40 /*
  41  * TODO:
  42  */
  43
  44 #include <stdio.h>
  45 #include <string.h>
  46 #include <sys/types.h>
  47 #include <sys/time.h>
  48 #include <syslog.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 __P((int));
  61 static void ChapLowerUp __P((int));
  62 static void ChapLowerDown __P((int));
  63 static void ChapInput __P((int, u_char *, int));
  64 static void ChapProtocolReject __P((int));
  65 static int  ChapPrintPkt __P((u_char *, int,
  66                               void (*) __P((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 __P((void *));
  89 static void ChapResponseTimeout __P((void *));
  90 static void ChapReceiveChallenge __P((chap_state *, u_char *, int, int));
  91 static void ChapRechallenge __P((void *));
  92 static void ChapReceiveResponse __P((chap_state *, u_char *, int, int));
  93 static void ChapReceiveSuccess __P((chap_state *, u_char *, int, int));
  94 static void ChapReceiveFailure __P((chap_state *, u_char *, int, int));
  95 static void ChapSendStatus __P((chap_state *, int));
  96 static void ChapSendChallenge __P((chap_state *));
  97 static void ChapSendResponse __P((chap_state *));
  98 static void ChapGenChallenge __P((chap_state *));
  99
 100 extern double drand48 __P((void));
 101 extern void srand48 __P((long));
 102
 103 /*
 104  * ChapInit - Initialize a CHAP unit.
 105  */
 106 static void
 107 ChapInit(unit)
 108     int unit;
 109 {
 110     chap_state *cstate = &chap[unit];
 111
 112     BZERO(cstate, sizeof(*cstate));
 113     cstate->unit = unit;
 114     cstate->clientstate = CHAPCS_INITIAL;
 115     cstate->serverstate = CHAPSS_INITIAL;
 116     cstate->timeouttime = CHAP_DEFTIMEOUT;
 117     cstate->max_transmits = CHAP_DEFTRANSMITS;
 118     /* random number generator is initialized in magic_init */
 119 }
 120
 121
 122 /*
 123  * ChapAuthWithPeer - Authenticate us with our peer (start client).
 124  *
 125  */
 126 void
 127 ChapAuthWithPeer(unit, our_name, digest)
 128     int unit;
 129     char *our_name;
 130     int digest;
 131 {
 132     chap_state *cstate = &chap[unit];
 133
 134     cstate->resp_name = our_name;
 135     cstate->resp_type = digest;
 136
 137     if (cstate->clientstate == CHAPCS_INITIAL ||
 138         cstate->clientstate == CHAPCS_PENDING) {
 139         /* lower layer isn't up - wait until later */
 140         cstate->clientstate = CHAPCS_PENDING;
 141         return;
 142     }
 143
 144     /*
 145      * We get here as a result of LCP coming up.
 146      * So even if CHAP was open before, we will
 147      * have to re-authenticate ourselves.
 148      */
 149     cstate->clientstate = CHAPCS_LISTEN;
 150 }
 151
 152
 153 /*
 154  * ChapAuthPeer - Authenticate our peer (start server).
 155  */
 156 void
 157 ChapAuthPeer(unit, our_name, digest)
 158     int unit;
 159     char *our_name;
 160     int digest;
 161 {
 162     chap_state *cstate = &chap[unit];
 163
 164     cstate->chal_name = our_name;
 165     cstate->chal_type = digest;
 166
 167     if (cstate->serverstate == CHAPSS_INITIAL ||
 168         cstate->serverstate == CHAPSS_PENDING) {
 169         /* lower layer isn't up - wait until later */
 170         cstate->serverstate = CHAPSS_PENDING;
 171         return;
 172     }
 173
 174     ChapGenChallenge(cstate);
 175     ChapSendChallenge(cstate);          /* crank it up dude! */
 176     cstate->serverstate = CHAPSS_INITIAL_CHAL;
 177 }
 178
 179
 180 /*
 181  * ChapChallengeTimeout - Timeout expired on sending challenge.
 182  */
 183 static void
 184 ChapChallengeTimeout(arg)
 185     void *arg;
 186 {
 187     chap_state *cstate = (chap_state *) arg;
 188
 189     /* if we aren't sending challenges, don't worry.  then again we */
 190     /* probably shouldn't be here either */
 191     if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
 192         cstate->serverstate != CHAPSS_RECHALLENGE)
 193         return;
 194
 195     if (cstate->chal_transmits >= cstate->max_transmits) {
 196         /* give up on peer */
 197         syslog(LOG_ERR, "Peer failed to respond to CHAP challenge");
 198         cstate->serverstate = CHAPSS_BADAUTH;
 199         auth_peer_fail(cstate->unit, PPP_CHAP);
 200         return;
 201     }
 202
 203     ChapSendChallenge(cstate);          /* Re-send challenge */
 204 }
 205
 206
 207 /*
 208  * ChapResponseTimeout - Timeout expired on sending response.
 209  */
 210 static void
 211 ChapResponseTimeout(arg)
 212     void *arg;
 213 {
 214     chap_state *cstate = (chap_state *) arg;
 215
 216     /* if we aren't sending a response, don't worry. */
 217     if (cstate->clientstate != CHAPCS_RESPONSE)
 218         return;
 219
 220     ChapSendResponse(cstate);           /* re-send response */
 221 }
 222
 223
 224 /*
 225  * ChapRechallenge - Time to challenge the peer again.
 226  */
 227 static void
 228 ChapRechallenge(arg)
 229     void *arg;
 230 {
 231     chap_state *cstate = (chap_state *) arg;
 232
 233     /* if we aren't sending a response, don't worry. */
 234     if (cstate->serverstate != CHAPSS_OPEN)
 235         return;
 236
 237     ChapGenChallenge(cstate);
 238     ChapSendChallenge(cstate);
 239     cstate->serverstate = CHAPSS_RECHALLENGE;
 240 }
 241
 242
 243 /*
 244  * ChapLowerUp - The lower layer is up.
 245  *
 246  * Start up if we have pending requests.
 247  */
 248 static void
 249 ChapLowerUp(unit)
 250     int unit;
 251 {
 252     chap_state *cstate = &chap[unit];
 253
 254     if (cstate->clientstate == CHAPCS_INITIAL)
 255         cstate->clientstate = CHAPCS_CLOSED;
 256     else if (cstate->clientstate == CHAPCS_PENDING)
 257         cstate->clientstate = CHAPCS_LISTEN;
 258
 259     if (cstate->serverstate == CHAPSS_INITIAL)
 260         cstate->serverstate = CHAPSS_CLOSED;
 261     else if (cstate->serverstate == CHAPSS_PENDING) {
 262         ChapGenChallenge(cstate);
 263         ChapSendChallenge(cstate);
 264         cstate->serverstate = CHAPSS_INITIAL_CHAL;
 265     }
 266 }
 267
 268
 269 /*
 270  * ChapLowerDown - The lower layer is down.
 271  *
 272  * Cancel all timeouts.
 273  */
 274 static void
 275 ChapLowerDown(unit)
 276     int unit;
 277 {
 278     chap_state *cstate = &chap[unit];
 279
 280     /* Timeout(s) pending?  Cancel if so. */
 281     if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
 282         cstate->serverstate == CHAPSS_RECHALLENGE)
 283         UNTIMEOUT(ChapChallengeTimeout, cstate);
 284     else if (cstate->serverstate == CHAPSS_OPEN
 285              && cstate->chal_interval != 0)
 286         UNTIMEOUT(ChapRechallenge, cstate);
 287     if (cstate->clientstate == CHAPCS_RESPONSE)
 288         UNTIMEOUT(ChapResponseTimeout, cstate);
 289
 290     cstate->clientstate = CHAPCS_INITIAL;
 291     cstate->serverstate = CHAPSS_INITIAL;
 292 }
 293
 294
 295 /*
 296  * ChapProtocolReject - Peer doesn't grok CHAP.
 297  */
 298 static void
 299 ChapProtocolReject(unit)
 300     int unit;
 301 {
 302     chap_state *cstate = &chap[unit];
 303
 304     if (cstate->serverstate != CHAPSS_INITIAL &&
 305         cstate->serverstate != CHAPSS_CLOSED)
 306         auth_peer_fail(unit, PPP_CHAP);
 307     if (cstate->clientstate != CHAPCS_INITIAL &&
 308         cstate->clientstate != CHAPCS_CLOSED)
 309         auth_withpeer_fail(unit, PPP_CHAP);
 310     ChapLowerDown(unit);                /* shutdown chap */
 311 }
 312
 313
 314 /*
 315  * ChapInput - Input CHAP packet.
 316  */
 317 static void
 318 ChapInput(unit, inpacket, packet_len)
 319     int unit;
 320     u_char *inpacket;
 321     int packet_len;
 322 {
 323     chap_state *cstate = &chap[unit];
 324     u_char *inp;
 325     u_char code, id;
 326     int len;
 327
 328     /*
 329      * Parse header (code, id and length).
 330      * If packet too short, drop it.
 331      */
 332     inp = inpacket;
 333     if (packet_len < CHAP_HEADERLEN) {
 334         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short header."));
 335         return;
 336     }
 337     GETCHAR(code, inp);
 338     GETCHAR(id, inp);
 339     GETSHORT(len, inp);
 340     if (len < CHAP_HEADERLEN) {
 341         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd illegal length."));
 342         return;
 343     }
 344     if (len > packet_len) {
 345         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short packet."));
 346         return;
 347     }
 348     len -= CHAP_HEADERLEN;
 349
 350     /*
 351      * Action depends on code (as in fact it usually does :-).
 352      */
 353     switch (code) {
 354     case CHAP_CHALLENGE:
 355         ChapReceiveChallenge(cstate, inp, id, len);
 356         break;
 357
 358     case CHAP_RESPONSE:
 359         ChapReceiveResponse(cstate, inp, id, len);
 360         break;
 361
 362     case CHAP_FAILURE:
 363         ChapReceiveFailure(cstate, inp, id, len);
 364         break;
 365
 366     case CHAP_SUCCESS:
 367         ChapReceiveSuccess(cstate, inp, id, len);
 368         break;
 369
 370     default:                            /* Need code reject? */
 371         syslog(LOG_WARNING, "Unknown CHAP code (%d) received.", code);
 372         break;
 373     }
 374 }
 375
 376
 377 /*
 378  * ChapReceiveChallenge - Receive Challenge and send Response.
 379  */
 380 static void
 381 ChapReceiveChallenge(cstate, inp, id, len)
 382     chap_state *cstate;
 383     u_char *inp;
 384     int id;
 385     int len;
 386 {
 387     int rchallenge_len;
 388     u_char *rchallenge;
 389     int secret_len;
 390     char secret[MAXSECRETLEN];
 391     char rhostname[256];
 392     MD5_CTX mdContext;
 393     u_char hash[MD5_SIGNATURE_SIZE];
 394
 395     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: Rcvd id %d.", id));
 396     if (cstate->clientstate == CHAPCS_CLOSED ||
 397         cstate->clientstate == CHAPCS_PENDING) {
 398         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: in state %d",
 399                    cstate->clientstate));
 400         return;
 401     }
 402
 403     if (len < 2) {
 404         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 405         return;
 406     }
 407
 408     GETCHAR(rchallenge_len, inp);
 409     len -= sizeof (u_char) + rchallenge_len;    /* now name field length */
 410     if (len < 0) {
 411         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 412         return;
 413     }
 414     rchallenge = inp;
 415     INCPTR(rchallenge_len, inp);
 416
 417     if (len >= sizeof(rhostname))
 418         len = sizeof(rhostname) - 1;
 419     BCOPY(inp, rhostname, len);
 420     rhostname[len] = '\000';
 421
 422     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: received name field '%s'",
 423                rhostname));
 424
 425     /* Microsoft doesn't send their name back in the PPP packet */
 426     if (remote_name[0] != 0 && (explicit_remote || rhostname[0] == 0)) {
 427         strncpy(rhostname, remote_name, sizeof(rhostname));
 428         rhostname[sizeof(rhostname) - 1] = 0;
 429         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: using '%s' as remote name",
 430                    rhostname));
 431     }
 432
 433     /* get secret for authenticating ourselves with the specified host */
 434     if (!get_secret(cstate->unit, cstate->resp_name, rhostname,
 435                     secret, &secret_len, 0)) {
 436         secret_len = 0;         /* assume null secret if can't find one */
 437         syslog(LOG_WARNING, "No CHAP secret found for authenticating us to %s",
 438                rhostname);
 439     }
 440
 441     /* cancel response send timeout if necessary */
 442     if (cstate->clientstate == CHAPCS_RESPONSE)
 443         UNTIMEOUT(ChapResponseTimeout, cstate);
 444
 445     cstate->resp_id = id;
 446     cstate->resp_transmits = 0;
 447
 448     /*  generate MD based on negotiated type */
 449     switch (cstate->resp_type) {
 450
 451     case CHAP_DIGEST_MD5:
 452         MD5Init(&mdContext);
 453         MD5Update(&mdContext, &cstate->resp_id, 1);
 454         MD5Update(&mdContext, secret, secret_len);
 455         MD5Update(&mdContext, rchallenge, rchallenge_len);
 456         MD5Final(hash, &mdContext);
 457         BCOPY(hash, cstate->response, MD5_SIGNATURE_SIZE);
 458         cstate->resp_length = MD5_SIGNATURE_SIZE;
 459         break;
 460
 461 #ifdef CHAPMS
 462     case CHAP_MICROSOFT:
 463         ChapMS(cstate, rchallenge, rchallenge_len, secret, secret_len);
 464         break;
 465 #endif
 466
 467     default:
 468         CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->resp_type));
 469         return;
 470     }
 471
 472     BZERO(secret, sizeof(secret));
 473     ChapSendResponse(cstate);
 474 }
 475
 476
 477 /*
 478  * ChapReceiveResponse - Receive and process response.
 479  */
 480 static void
 481 ChapReceiveResponse(cstate, inp, id, len)
 482     chap_state *cstate;
 483     u_char *inp;
 484     int id;
 485     int len;
 486 {
 487     u_char *remmd, remmd_len;
 488     int secret_len, old_state;
 489     int code;
 490     char rhostname[256];
 491     MD5_CTX mdContext;
 492     char secret[MAXSECRETLEN];
 493     u_char hash[MD5_SIGNATURE_SIZE];
 494
 495     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: Rcvd id %d.", id));
 496
 497     if (cstate->serverstate == CHAPSS_CLOSED ||
 498         cstate->serverstate == CHAPSS_PENDING) {
 499         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: in state %d",
 500                    cstate->serverstate));
 501         return;
 502     }
 503
 504     if (id != cstate->chal_id)
 505         return;                 /* doesn't match ID of last challenge */
 506
 507     /*
 508      * If we have received a duplicate or bogus Response,
 509      * we have to send the same answer (Success/Failure)
 510      * as we did for the first Response we saw.
 511      */
 512     if (cstate->serverstate == CHAPSS_OPEN) {
 513         ChapSendStatus(cstate, CHAP_SUCCESS);
 514         return;
 515     }
 516     if (cstate->serverstate == CHAPSS_BADAUTH) {
 517         ChapSendStatus(cstate, CHAP_FAILURE);
 518         return;
 519     }
 520
 521     if (len < 2) {
 522         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 523         return;
 524     }
 525     GETCHAR(remmd_len, inp);            /* get length of MD */
 526     remmd = inp;                        /* get pointer to MD */
 527     INCPTR(remmd_len, inp);
 528
 529     len -= sizeof (u_char) + remmd_len;
 530     if (len < 0) {
 531         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 532         return;
 533     }
 534
 535     UNTIMEOUT(ChapChallengeTimeout, cstate);
 536
 537     if (len >= sizeof(rhostname))
 538         len = sizeof(rhostname) - 1;
 539     BCOPY(inp, rhostname, len);
 540     rhostname[len] = '\000';
 541
 542     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: received name field: %s",
 543                rhostname));
 544
 545     /*
 546      * Get secret for authenticating them with us,
 547      * do the hash ourselves, and compare the result.
 548      */
 549     code = CHAP_FAILURE;
 550     if (!get_secret(cstate->unit, rhostname, cstate->chal_name,
 551                    secret, &secret_len, 1)) {
 552         syslog(LOG_WARNING, "No CHAP secret found for authenticating %s",
 553                rhostname);
 554     } else {
 555
 556         /*  generate MD based on negotiated type */
 557         switch (cstate->chal_type) {
 558
 559         case CHAP_DIGEST_MD5:           /* only MD5 is defined for now */
 560             if (remmd_len != MD5_SIGNATURE_SIZE)
 561                 break;                  /* it's not even the right length */
 562             MD5Init(&mdContext);
 563             MD5Update(&mdContext, &cstate->chal_id, 1);
 564             MD5Update(&mdContext, secret, secret_len);
 565             MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
 566             MD5Final(hash, &mdContext);
 567
 568             /* compare local and remote MDs and send the appropriate status */
 569             if (memcmp (hash, remmd, MD5_SIGNATURE_SIZE) == 0)
 570                 code = CHAP_SUCCESS;    /* they are the same! */
 571             break;
 572
 573         default:
 574             CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->chal_type));
 575         }
 576     }
 577
 578     BZERO(secret, sizeof(secret));
 579     ChapSendStatus(cstate, code);
 580
 581     if (code == CHAP_SUCCESS) {
 582         old_state = cstate->serverstate;
 583         cstate->serverstate = CHAPSS_OPEN;
 584         if (old_state == CHAPSS_INITIAL_CHAL) {
 585             auth_peer_success(cstate->unit, PPP_CHAP, rhostname, len);
 586         }
 587         if (cstate->chal_interval != 0)
 588             TIMEOUT(ChapRechallenge, cstate, cstate->chal_interval);
 589
 590     } else {
 591         syslog(LOG_ERR, "CHAP peer authentication failed");
 592         cstate->serverstate = CHAPSS_BADAUTH;
 593         auth_peer_fail(cstate->unit, PPP_CHAP);
 594     }
 595 }
 596
 597 /*
 598  * ChapReceiveSuccess - Receive Success
 599  */
 600 static void
 601 ChapReceiveSuccess(cstate, inp, id, len)
 602     chap_state *cstate;
 603     u_char *inp;
 604     u_char id;
 605     int len;
 606 {
 607
 608     CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: Rcvd id %d.", id));
 609
 610     if (cstate->clientstate == CHAPCS_OPEN)
 611         /* presumably an answer to a duplicate response */
 612         return;
 613
 614     if (cstate->clientstate != CHAPCS_RESPONSE) {
 615         /* don't know what this is */
 616         CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: in state %d\n",
 617                    cstate->clientstate));
 618         return;
 619     }
 620
 621     UNTIMEOUT(ChapResponseTimeout, cstate);
 622
 623     /*
 624      * Print message.
 625      */
 626     if (len > 0)
 627         PRINTMSG(inp, len);
 628
 629     cstate->clientstate = CHAPCS_OPEN;
 630
 631     auth_withpeer_success(cstate->unit, PPP_CHAP);
 632 }
 633
 634
 635 /*
 636  * ChapReceiveFailure - Receive failure.
 637  */
 638 static void
 639 ChapReceiveFailure(cstate, inp, id, len)
 640     chap_state *cstate;
 641     u_char *inp;
 642     u_char id;
 643     int len;
 644 {
 645     CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: Rcvd id %d.", id));
 646
 647     if (cstate->clientstate != CHAPCS_RESPONSE) {
 648         /* don't know what this is */
 649         CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: in state %d\n",
 650                    cstate->clientstate));
 651         return;
 652     }
 653
 654     UNTIMEOUT(ChapResponseTimeout, cstate);
 655
 656     /*
 657      * Print message.
 658      */
 659     if (len > 0)
 660         PRINTMSG(inp, len);
 661
 662     syslog(LOG_ERR, "CHAP authentication failed");
 663     auth_withpeer_fail(cstate->unit, PPP_CHAP);
 664 }
 665
 666
 667 /*
 668  * ChapSendChallenge - Send an Authenticate challenge.
 669  */
 670 static void
 671 ChapSendChallenge(cstate)
 672     chap_state *cstate;
 673 {
 674     u_char *outp;
 675     int chal_len, name_len;
 676     int outlen;
 677
 678     chal_len = cstate->chal_len;
 679     name_len = strlen(cstate->chal_name);
 680     outlen = CHAP_HEADERLEN + sizeof (u_char) + chal_len + name_len;
 681     outp = outpacket_buf;
 682
 683     MAKEHEADER(outp, PPP_CHAP);         /* paste in a CHAP header */
 684
 685     PUTCHAR(CHAP_CHALLENGE, outp);
 686     PUTCHAR(cstate->chal_id, outp);
 687     PUTSHORT(outlen, outp);
 688
 689     PUTCHAR(chal_len, outp);            /* put length of challenge */
 690     BCOPY(cstate->challenge, outp, chal_len);
 691     INCPTR(chal_len, outp);
 692
 693     BCOPY(cstate->chal_name, outp, name_len);   /* append hostname */
 694
 695     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 696
 697     CHAPDEBUG((LOG_INFO, "ChapSendChallenge: Sent id %d.", cstate->chal_id));
 698
 699     TIMEOUT(ChapChallengeTimeout, cstate, cstate->timeouttime);
 700     ++cstate->chal_transmits;
 701 }
 702
 703
 704 /*
 705  * ChapSendStatus - Send a status response (ack or nak).
 706  */
 707 static void
 708 ChapSendStatus(cstate, code)
 709     chap_state *cstate;
 710     int code;
 711 {
 712     u_char *outp;
 713     int outlen, msglen;
 714     char msg[256];
 715
 716     if (code == CHAP_SUCCESS)
 717         sprintf(msg, "Welcome to %s.", hostname);
 718     else
 719         sprintf(msg, "I don't like you.  Go 'way.");
 720     msglen = strlen(msg);
 721
 722     outlen = CHAP_HEADERLEN + msglen;
 723     outp = outpacket_buf;
 724
 725     MAKEHEADER(outp, PPP_CHAP); /* paste in a header */
 726
 727     PUTCHAR(code, outp);
 728     PUTCHAR(cstate->chal_id, outp);
 729     PUTSHORT(outlen, outp);
 730     BCOPY(msg, outp, msglen);
 731     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 732
 733     CHAPDEBUG((LOG_INFO, "ChapSendStatus: Sent code %d, id %d.", code,
 734                cstate->chal_id));
 735 }
 736
 737 /*
 738  * ChapGenChallenge is used to generate a pseudo-random challenge string of
 739  * a pseudo-random length between min_len and max_len.  The challenge
 740  * string and its length are stored in *cstate, and various other fields of
 741  * *cstate are initialized.
 742  */
 743
 744 static void
 745 ChapGenChallenge(cstate)
 746     chap_state *cstate;
 747 {
 748     int chal_len;
 749     u_char *ptr = cstate->challenge;
 750     unsigned int i;
 751
 752     /* pick a random challenge length between MIN_CHALLENGE_LENGTH and
 753        MAX_CHALLENGE_LENGTH */
 754     chal_len =  (unsigned) ((drand48() *
 755                              (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
 756                             MIN_CHALLENGE_LENGTH);
 757     cstate->chal_len = chal_len;
 758     cstate->chal_id = ++cstate->id;
 759     cstate->chal_transmits = 0;
 760
 761     /* generate a random string */
 762     for (i = 0; i < chal_len; i++ )
 763         *ptr++ = (char) (drand48() * 0xff);
 764 }
 765
 766 /*
 767  * ChapSendResponse - send a response packet with values as specified
 768  * in *cstate.
 769  */
 770 /* ARGSUSED */
 771 static void
 772 ChapSendResponse(cstate)
 773     chap_state *cstate;
 774 {
 775     u_char *outp;
 776     int outlen, md_len, name_len;
 777
 778     md_len = cstate->resp_length;
 779     name_len = strlen(cstate->resp_name);
 780     outlen = CHAP_HEADERLEN + sizeof (u_char) + md_len + name_len;
 781     outp = outpacket_buf;
 782
 783     MAKEHEADER(outp, PPP_CHAP);
 784
 785     PUTCHAR(CHAP_RESPONSE, outp);       /* we are a response */
 786     PUTCHAR(cstate->resp_id, outp);     /* copy id from challenge packet */
 787     PUTSHORT(outlen, outp);             /* packet length */
 788
 789     PUTCHAR(md_len, outp);              /* length of MD */
 790     BCOPY(cstate->response, outp, md_len);      /* copy MD to buffer */
 791     INCPTR(md_len, outp);
 792
 793     BCOPY(cstate->resp_name, outp, name_len); /* append our name */
 794
 795     /* send the packet */
 796     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 797
 798     cstate->clientstate = CHAPCS_RESPONSE;
 799     TIMEOUT(ChapResponseTimeout, cstate, cstate->timeouttime);
 800     ++cstate->resp_transmits;
 801 }
 802
 803 /*
 804  * ChapPrintPkt - print the contents of a CHAP packet.
 805  */
 806 static char *ChapCodenames[] = {
 807     "Challenge", "Response", "Success", "Failure"
 808 };
 809
 810 static int
 811 ChapPrintPkt(p, plen, printer, arg)
 812     u_char *p;
 813     int plen;
 814     void (*printer) __P((void *, char *, ...));
 815     void *arg;
 816 {
 817     int code, id, len;
 818     int clen, nlen;
 819     u_char x;
 820
 821     if (plen < CHAP_HEADERLEN)
 822         return 0;
 823     GETCHAR(code, p);
 824     GETCHAR(id, p);
 825     GETSHORT(len, p);
 826     if (len < CHAP_HEADERLEN || len > plen)
 827         return 0;
 828
 829     if (code >= 1 && code <= sizeof(ChapCodenames) / sizeof(char *))
 830         printer(arg, " %s", ChapCodenames[code-1]);
 831     else
 832         printer(arg, " code=0x%x", code);
 833     printer(arg, " id=0x%x", id);
 834     len -= CHAP_HEADERLEN;
 835     switch (code) {
 836     case CHAP_CHALLENGE:
 837     case CHAP_RESPONSE:
 838         if (len < 1)
 839             break;
 840         clen = p[0];
 841         if (len < clen + 1)
 842             break;
 843         ++p;
 844         nlen = len - clen - 1;
 845         printer(arg, " <");
 846         for (; clen > 0; --clen) {
 847             GETCHAR(x, p);
 848             printer(arg, "%.2x", x);
 849         }
 850         printer(arg, ">, name = ");
 851         print_string((char *)p, nlen, printer, arg);
 852         break;
 853     case CHAP_FAILURE:
 854     case CHAP_SUCCESS:
 855         printer(arg, " ");
 856         print_string((char *)p, len, printer, arg);
 857         break;
 858     default:
 859         for (clen = len; clen > 0; --clen) {
 860             GETCHAR(x, p);
 861             printer(arg, " %.2x", x);
 862         }
 863     }
 864
 865     return len + CHAP_HEADERLEN;
 866 }