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 1.13 1996/07/01 01:12:09 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((caddr_t));
  89 static void ChapResponseTimeout __P((caddr_t));
  90 static void ChapReceiveChallenge __P((chap_state *, u_char *, int, int));
  91 static void ChapReceiveResponse __P((chap_state *, u_char *, int, int));
  92 static void ChapReceiveSuccess __P((chap_state *, u_char *, int, int));
  93 static void ChapReceiveFailure __P((chap_state *, u_char *, int, int));
  94 static void ChapSendStatus __P((chap_state *, int));
  95 static void ChapSendChallenge __P((chap_state *));
  96 static void ChapSendResponse __P((chap_state *));
  97 static void ChapGenChallenge __P((chap_state *));
  98
  99 extern double drand48 __P((void));
 100 extern void srand48 __P((long));
 101
 102 /*
 103  * ChapInit - Initialize a CHAP unit.
 104  */
 105 static void
 106 ChapInit(unit)
 107     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(unit, our_name, digest)
 127     int unit;
 128     char *our_name;
 129     int digest;
 130 {
 131     chap_state *cstate = &chap[unit];
 132
 133     cstate->resp_name = our_name;
 134     cstate->resp_type = digest;
 135
 136     if (cstate->clientstate == CHAPCS_INITIAL ||
 137         cstate->clientstate == CHAPCS_PENDING) {
 138         /* lower layer isn't up - wait until later */
 139         cstate->clientstate = CHAPCS_PENDING;
 140         return;
 141     }
 142
 143     /*
 144      * We get here as a result of LCP coming up.
 145      * So even if CHAP was open before, we will
 146      * have to re-authenticate ourselves.
 147      */
 148     cstate->clientstate = CHAPCS_LISTEN;
 149 }
 150
 151
 152 /*
 153  * ChapAuthPeer - Authenticate our peer (start server).
 154  */
 155 void
 156 ChapAuthPeer(unit, our_name, digest)
 157     int unit;
 158     char *our_name;
 159     int digest;
 160 {
 161     chap_state *cstate = &chap[unit];
 162
 163     cstate->chal_name = our_name;
 164     cstate->chal_type = digest;
 165
 166     if (cstate->serverstate == CHAPSS_INITIAL ||
 167         cstate->serverstate == CHAPSS_PENDING) {
 168         /* lower layer isn't up - wait until later */
 169         cstate->serverstate = CHAPSS_PENDING;
 170         return;
 171     }
 172
 173     ChapGenChallenge(cstate);
 174     ChapSendChallenge(cstate);          /* crank it up dude! */
 175     cstate->serverstate = CHAPSS_INITIAL_CHAL;
 176 }
 177
 178
 179 /*
 180  * ChapChallengeTimeout - Timeout expired on sending challenge.
 181  */
 182 static void
 183 ChapChallengeTimeout(arg)
 184     caddr_t arg;
 185 {
 186     chap_state *cstate = (chap_state *) arg;
 187
 188     /* if we aren't sending challenges, don't worry.  then again we */
 189     /* probably shouldn't be here either */
 190     if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
 191         cstate->serverstate != CHAPSS_RECHALLENGE)
 192         return;
 193
 194     if (cstate->chal_transmits >= cstate->max_transmits) {
 195         /* give up on peer */
 196         syslog(LOG_ERR, "Peer failed to respond to CHAP challenge");
 197         cstate->serverstate = CHAPSS_BADAUTH;
 198         auth_peer_fail(cstate->unit, PPP_CHAP);
 199         return;
 200     }
 201
 202     ChapSendChallenge(cstate);          /* Re-send challenge */
 203 }
 204
 205
 206 /*
 207  * ChapResponseTimeout - Timeout expired on sending response.
 208  */
 209 static void
 210 ChapResponseTimeout(arg)
 211     caddr_t arg;
 212 {
 213     chap_state *cstate = (chap_state *) arg;
 214
 215     /* if we aren't sending a response, don't worry. */
 216     if (cstate->clientstate != CHAPCS_RESPONSE)
 217         return;
 218
 219     ChapSendResponse(cstate);           /* re-send response */
 220 }
 221
 222
 223 /*
 224  * ChapRechallenge - Time to challenge the peer again.
 225  */
 226 static void
 227 ChapRechallenge(arg)
 228     caddr_t arg;
 229 {
 230     chap_state *cstate = (chap_state *) arg;
 231
 232     /* if we aren't sending a response, don't worry. */
 233     if (cstate->serverstate != CHAPSS_OPEN)
 234         return;
 235
 236     ChapGenChallenge(cstate);
 237     ChapSendChallenge(cstate);
 238     cstate->serverstate = CHAPSS_RECHALLENGE;
 239 }
 240
 241
 242 /*
 243  * ChapLowerUp - The lower layer is up.
 244  *
 245  * Start up if we have pending requests.
 246  */
 247 static void
 248 ChapLowerUp(unit)
 249     int unit;
 250 {
 251     chap_state *cstate = &chap[unit];
 252
 253     if (cstate->clientstate == CHAPCS_INITIAL)
 254         cstate->clientstate = CHAPCS_CLOSED;
 255     else if (cstate->clientstate == CHAPCS_PENDING)
 256         cstate->clientstate = CHAPCS_LISTEN;
 257
 258     if (cstate->serverstate == CHAPSS_INITIAL)
 259         cstate->serverstate = CHAPSS_CLOSED;
 260     else if (cstate->serverstate == CHAPSS_PENDING) {
 261         ChapGenChallenge(cstate);
 262         ChapSendChallenge(cstate);
 263         cstate->serverstate = CHAPSS_INITIAL_CHAL;
 264     }
 265 }
 266
 267
 268 /*
 269  * ChapLowerDown - The lower layer is down.
 270  *
 271  * Cancel all timeouts.
 272  */
 273 static void
 274 ChapLowerDown(unit)
 275     int unit;
 276 {
 277     chap_state *cstate = &chap[unit];
 278
 279     /* Timeout(s) pending?  Cancel if so. */
 280     if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
 281         cstate->serverstate == CHAPSS_RECHALLENGE)
 282         UNTIMEOUT(ChapChallengeTimeout, (caddr_t) cstate);
 283     else if (cstate->serverstate == CHAPSS_OPEN
 284              && cstate->chal_interval != 0)
 285         UNTIMEOUT(ChapRechallenge, (caddr_t) cstate);
 286     if (cstate->clientstate == CHAPCS_RESPONSE)
 287         UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 288
 289     cstate->clientstate = CHAPCS_INITIAL;
 290     cstate->serverstate = CHAPSS_INITIAL;
 291 }
 292
 293
 294 /*
 295  * ChapProtocolReject - Peer doesn't grok CHAP.
 296  */
 297 static void
 298 ChapProtocolReject(unit)
 299     int unit;
 300 {
 301     chap_state *cstate = &chap[unit];
 302
 303     if (cstate->serverstate != CHAPSS_INITIAL &&
 304         cstate->serverstate != CHAPSS_CLOSED)
 305         auth_peer_fail(unit, PPP_CHAP);
 306     if (cstate->clientstate != CHAPCS_INITIAL &&
 307         cstate->clientstate != CHAPCS_CLOSED)
 308         auth_withpeer_fail(unit, PPP_CHAP);
 309     ChapLowerDown(unit);                /* shutdown chap */
 310 }
 311
 312
 313 /*
 314  * ChapInput - Input CHAP packet.
 315  */
 316 static void
 317 ChapInput(unit, inpacket, packet_len)
 318     int unit;
 319     u_char *inpacket;
 320     int packet_len;
 321 {
 322     chap_state *cstate = &chap[unit];
 323     u_char *inp;
 324     u_char code, id;
 325     int len;
 326
 327     /*
 328      * Parse header (code, id and length).
 329      * If packet too short, drop it.
 330      */
 331     inp = inpacket;
 332     if (packet_len < CHAP_HEADERLEN) {
 333         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short header."));
 334         return;
 335     }
 336     GETCHAR(code, inp);
 337     GETCHAR(id, inp);
 338     GETSHORT(len, inp);
 339     if (len < CHAP_HEADERLEN) {
 340         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd illegal length."));
 341         return;
 342     }
 343     if (len > packet_len) {
 344         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short packet."));
 345         return;
 346     }
 347     len -= CHAP_HEADERLEN;
 348
 349     /*
 350      * Action depends on code (as in fact it usually does :-).
 351      */
 352     switch (code) {
 353     case CHAP_CHALLENGE:
 354         ChapReceiveChallenge(cstate, inp, id, len);
 355         break;
 356
 357     case CHAP_RESPONSE:
 358         ChapReceiveResponse(cstate, inp, id, len);
 359         break;
 360
 361     case CHAP_FAILURE:
 362         ChapReceiveFailure(cstate, inp, id, len);
 363         break;
 364
 365     case CHAP_SUCCESS:
 366         ChapReceiveSuccess(cstate, inp, id, len);
 367         break;
 368
 369     default:                            /* Need code reject? */
 370         syslog(LOG_WARNING, "Unknown CHAP code (%d) received.", code);
 371         break;
 372     }
 373 }
 374
 375
 376 /*
 377  * ChapReceiveChallenge - Receive Challenge and send Response.
 378  */
 379 static void
 380 ChapReceiveChallenge(cstate, inp, id, len)
 381     chap_state *cstate;
 382     u_char *inp;
 383     int id;
 384     int len;
 385 {
 386     int rchallenge_len;
 387     u_char *rchallenge;
 388     int secret_len;
 389     char secret[MAXSECRETLEN];
 390     char rhostname[256];
 391     MD5_CTX mdContext;
 392
 393     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: Rcvd id %d.", id));
 394     if (cstate->clientstate == CHAPCS_CLOSED ||
 395         cstate->clientstate == CHAPCS_PENDING) {
 396         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: in state %d",
 397                    cstate->clientstate));
 398         return;
 399     }
 400
 401     if (len < 2) {
 402         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 403         return;
 404     }
 405
 406     GETCHAR(rchallenge_len, inp);
 407     len -= sizeof (u_char) + rchallenge_len;    /* now name field length */
 408     if (len < 0) {
 409         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 410         return;
 411     }
 412     rchallenge = inp;
 413     INCPTR(rchallenge_len, inp);
 414
 415     if (len >= sizeof(rhostname))
 416         len = sizeof(rhostname) - 1;
 417     BCOPY(inp, rhostname, len);
 418     rhostname[len] = '\000';
 419
 420     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: received name field '%s'",
 421                rhostname));
 422
 423     /* Microsoft doesn't send their name back in the PPP packet */
 424     if (rhostname[0] == 0 && cstate->resp_type == CHAP_MICROSOFT) {
 425         strcpy(rhostname, remote_name);
 426         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: using '%s' as remote name",
 427                    rhostname));
 428     }
 429
 430     /* get secret for authenticating ourselves with the specified host */
 431     if (!get_secret(cstate->unit, cstate->resp_name, rhostname,
 432                     secret, &secret_len, 0)) {
 433         secret_len = 0;         /* assume null secret if can't find one */
 434         syslog(LOG_WARNING, "No CHAP secret found for authenticating us to %s",
 435                rhostname);
 436     }
 437
 438     /* cancel response send timeout if necessary */
 439     if (cstate->clientstate == CHAPCS_RESPONSE)
 440         UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 441
 442     cstate->resp_id = id;
 443     cstate->resp_transmits = 0;
 444
 445     /*  generate MD based on negotiated type */
 446     switch (cstate->resp_type) {
 447
 448     case CHAP_DIGEST_MD5:
 449         MD5Init(&mdContext);
 450         MD5Update(&mdContext, &cstate->resp_id, 1);
 451         MD5Update(&mdContext, secret, secret_len);
 452         MD5Update(&mdContext, rchallenge, rchallenge_len);
 453         MD5Final(&mdContext);
 454         BCOPY(mdContext.digest, cstate->response, MD5_SIGNATURE_SIZE);
 455         cstate->resp_length = MD5_SIGNATURE_SIZE;
 456         break;
 457
 458 #ifdef CHAPMS
 459     case CHAP_MICROSOFT:
 460         ChapMS(cstate, rchallenge, rchallenge_len, secret, secret_len);
 461         break;
 462 #endif
 463
 464     default:
 465         CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->resp_type));
 466         return;
 467     }
 468
 469     BZERO(secret, sizeof(secret));
 470     ChapSendResponse(cstate);
 471 }
 472
 473
 474 /*
 475  * ChapReceiveResponse - Receive and process response.
 476  */
 477 static void
 478 ChapReceiveResponse(cstate, inp, id, len)
 479     chap_state *cstate;
 480     u_char *inp;
 481     int id;
 482     int len;
 483 {
 484     u_char *remmd, remmd_len;
 485     int secret_len, old_state;
 486     int code;
 487     char rhostname[256];
 488     MD5_CTX mdContext;
 489     char secret[MAXSECRETLEN];
 490
 491     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: Rcvd id %d.", id));
 492
 493     if (cstate->serverstate == CHAPSS_CLOSED ||
 494         cstate->serverstate == CHAPSS_PENDING) {
 495         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: in state %d",
 496                    cstate->serverstate));
 497         return;
 498     }
 499
 500     if (id != cstate->chal_id)
 501         return;                 /* doesn't match ID of last challenge */
 502
 503     /*
 504      * If we have received a duplicate or bogus Response,
 505      * we have to send the same answer (Success/Failure)
 506      * as we did for the first Response we saw.
 507      */
 508     if (cstate->serverstate == CHAPSS_OPEN) {
 509         ChapSendStatus(cstate, CHAP_SUCCESS);
 510         return;
 511     }
 512     if (cstate->serverstate == CHAPSS_BADAUTH) {
 513         ChapSendStatus(cstate, CHAP_FAILURE);
 514         return;
 515     }
 516
 517     if (len < 2) {
 518         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 519         return;
 520     }
 521     GETCHAR(remmd_len, inp);            /* get length of MD */
 522     remmd = inp;                        /* get pointer to MD */
 523     INCPTR(remmd_len, inp);
 524
 525     len -= sizeof (u_char) + remmd_len;
 526     if (len < 0) {
 527         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 528         return;
 529     }
 530
 531     UNTIMEOUT(ChapChallengeTimeout, (caddr_t) cstate);
 532
 533     if (len >= sizeof(rhostname))
 534         len = sizeof(rhostname) - 1;
 535     BCOPY(inp, rhostname, len);
 536     rhostname[len] = '\000';
 537
 538     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: received name field: %s",
 539                rhostname));
 540
 541     /*
 542      * Get secret for authenticating them with us,
 543      * do the hash ourselves, and compare the result.
 544      */
 545     code = CHAP_FAILURE;
 546     if (!get_secret(cstate->unit, rhostname, cstate->chal_name,
 547                    secret, &secret_len, 1)) {
 548         syslog(LOG_WARNING, "No CHAP secret found for authenticating %s",
 549                rhostname);
 550     } else {
 551
 552         /*  generate MD based on negotiated type */
 553         switch (cstate->chal_type) {
 554
 555         case CHAP_DIGEST_MD5:           /* only MD5 is defined for now */
 556             if (remmd_len != MD5_SIGNATURE_SIZE)
 557                 break;                  /* it's not even the right length */
 558             MD5Init(&mdContext);
 559             MD5Update(&mdContext, &cstate->chal_id, 1);
 560             MD5Update(&mdContext, secret, secret_len);
 561             MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
 562             MD5Final(&mdContext);
 563
 564             /* compare local and remote MDs and send the appropriate status */
 565             if (memcmp (mdContext.digest, remmd, MD5_SIGNATURE_SIZE) == 0)
 566                 code = CHAP_SUCCESS;    /* they are the same! */
 567             break;
 568
 569         default:
 570             CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->chal_type));
 571         }
 572     }
 573
 574     BZERO(secret, sizeof(secret));
 575     ChapSendStatus(cstate, code);
 576
 577     if (code == CHAP_SUCCESS) {
 578         old_state = cstate->serverstate;
 579         cstate->serverstate = CHAPSS_OPEN;
 580         if (old_state == CHAPSS_INITIAL_CHAL) {
 581             auth_peer_success(cstate->unit, PPP_CHAP, rhostname, len);
 582         }
 583         if (cstate->chal_interval != 0)
 584             TIMEOUT(ChapRechallenge, (caddr_t) cstate, cstate->chal_interval);
 585
 586     } else {
 587         syslog(LOG_ERR, "CHAP peer authentication failed");
 588         cstate->serverstate = CHAPSS_BADAUTH;
 589         auth_peer_fail(cstate->unit, PPP_CHAP);
 590     }
 591 }
 592
 593 /*
 594  * ChapReceiveSuccess - Receive Success
 595  */
 596 static void
 597 ChapReceiveSuccess(cstate, inp, id, len)
 598     chap_state *cstate;
 599     u_char *inp;
 600     u_char id;
 601     int len;
 602 {
 603
 604     CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: Rcvd id %d.", id));
 605
 606     if (cstate->clientstate == CHAPCS_OPEN)
 607         /* presumably an answer to a duplicate response */
 608         return;
 609
 610     if (cstate->clientstate != CHAPCS_RESPONSE) {
 611         /* don't know what this is */
 612         CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: in state %d\n",
 613                    cstate->clientstate));
 614         return;
 615     }
 616
 617     UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 618
 619     /*
 620      * Print message.
 621      */
 622     if (len > 0)
 623         PRINTMSG(inp, len);
 624
 625     cstate->clientstate = CHAPCS_OPEN;
 626
 627     auth_withpeer_success(cstate->unit, PPP_CHAP);
 628 }
 629
 630
 631 /*
 632  * ChapReceiveFailure - Receive failure.
 633  */
 634 static void
 635 ChapReceiveFailure(cstate, inp, id, len)
 636     chap_state *cstate;
 637     u_char *inp;
 638     u_char id;
 639     int len;
 640 {
 641     CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: Rcvd id %d.", id));
 642
 643     if (cstate->clientstate != CHAPCS_RESPONSE) {
 644         /* don't know what this is */
 645         CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: in state %d\n",
 646                    cstate->clientstate));
 647         return;
 648     }
 649
 650     UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 651
 652     /*
 653      * Print message.
 654      */
 655     if (len > 0)
 656         PRINTMSG(inp, len);
 657
 658     syslog(LOG_ERR, "CHAP authentication failed");
 659     auth_withpeer_fail(cstate->unit, PPP_CHAP);
 660 }
 661
 662
 663 /*
 664  * ChapSendChallenge - Send an Authenticate challenge.
 665  */
 666 static void
 667 ChapSendChallenge(cstate)
 668     chap_state *cstate;
 669 {
 670     u_char *outp;
 671     int chal_len, name_len;
 672     int outlen;
 673
 674     chal_len = cstate->chal_len;
 675     name_len = strlen(cstate->chal_name);
 676     outlen = CHAP_HEADERLEN + sizeof (u_char) + chal_len + name_len;
 677     outp = outpacket_buf;
 678
 679     MAKEHEADER(outp, PPP_CHAP);         /* paste in a CHAP header */
 680
 681     PUTCHAR(CHAP_CHALLENGE, outp);
 682     PUTCHAR(cstate->chal_id, outp);
 683     PUTSHORT(outlen, outp);
 684
 685     PUTCHAR(chal_len, outp);            /* put length of challenge */
 686     BCOPY(cstate->challenge, outp, chal_len);
 687     INCPTR(chal_len, outp);
 688
 689     BCOPY(cstate->chal_name, outp, name_len);   /* append hostname */
 690
 691     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 692
 693     CHAPDEBUG((LOG_INFO, "ChapSendChallenge: Sent id %d.", cstate->chal_id));
 694
 695     TIMEOUT(ChapChallengeTimeout, (caddr_t) cstate, cstate->timeouttime);
 696     ++cstate->chal_transmits;
 697 }
 698
 699
 700 /*
 701  * ChapSendStatus - Send a status response (ack or nak).
 702  */
 703 static void
 704 ChapSendStatus(cstate, code)
 705     chap_state *cstate;
 706     int code;
 707 {
 708     u_char *outp;
 709     int outlen, msglen;
 710     char msg[256];
 711
 712     if (code == CHAP_SUCCESS)
 713         sprintf(msg, "Welcome to %s.", hostname);
 714     else
 715         sprintf(msg, "I don't like you.  Go 'way.");
 716     msglen = strlen(msg);
 717
 718     outlen = CHAP_HEADERLEN + msglen;
 719     outp = outpacket_buf;
 720
 721     MAKEHEADER(outp, PPP_CHAP); /* paste in a header */
 722
 723     PUTCHAR(code, outp);
 724     PUTCHAR(cstate->chal_id, outp);
 725     PUTSHORT(outlen, outp);
 726     BCOPY(msg, outp, msglen);
 727     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 728
 729     CHAPDEBUG((LOG_INFO, "ChapSendStatus: Sent code %d, id %d.", code,
 730                cstate->chal_id));
 731 }
 732
 733 /*
 734  * ChapGenChallenge is used to generate a pseudo-random challenge string of
 735  * a pseudo-random length between min_len and max_len.  The challenge
 736  * string and its length are stored in *cstate, and various other fields of
 737  * *cstate are initialized.
 738  */
 739
 740 static void
 741 ChapGenChallenge(cstate)
 742     chap_state *cstate;
 743 {
 744     int chal_len;
 745     u_char *ptr = cstate->challenge;
 746     unsigned int i;
 747
 748     /* pick a random challenge length between MIN_CHALLENGE_LENGTH and
 749        MAX_CHALLENGE_LENGTH */
 750     chal_len =  (unsigned) ((drand48() *
 751                              (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
 752                             MIN_CHALLENGE_LENGTH);
 753     cstate->chal_len = chal_len;
 754     cstate->chal_id = ++cstate->id;
 755     cstate->chal_transmits = 0;
 756
 757     /* generate a random string */
 758     for (i = 0; i < chal_len; i++ )
 759         *ptr++ = (char) (drand48() * 0xff);
 760 }
 761
 762 /*
 763  * ChapSendResponse - send a response packet with values as specified
 764  * in *cstate.
 765  */
 766 /* ARGSUSED */
 767 static void
 768 ChapSendResponse(cstate)
 769     chap_state *cstate;
 770 {
 771     u_char *outp;
 772     int outlen, md_len, name_len;
 773
 774     md_len = cstate->resp_length;
 775     name_len = strlen(cstate->resp_name);
 776     outlen = CHAP_HEADERLEN + sizeof (u_char) + md_len + name_len;
 777     outp = outpacket_buf;
 778
 779     MAKEHEADER(outp, PPP_CHAP);
 780
 781     PUTCHAR(CHAP_RESPONSE, outp);       /* we are a response */
 782     PUTCHAR(cstate->resp_id, outp);     /* copy id from challenge packet */
 783     PUTSHORT(outlen, outp);             /* packet length */
 784
 785     PUTCHAR(md_len, outp);              /* length of MD */
 786     BCOPY(cstate->response, outp, md_len);      /* copy MD to buffer */
 787     INCPTR(md_len, outp);
 788
 789     BCOPY(cstate->resp_name, outp, name_len); /* append our name */
 790
 791     /* send the packet */
 792     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 793
 794     cstate->clientstate = CHAPCS_RESPONSE;
 795     TIMEOUT(ChapResponseTimeout, (caddr_t) cstate, cstate->timeouttime);
 796     ++cstate->resp_transmits;
 797 }
 798
 799 /*
 800  * ChapPrintPkt - print the contents of a CHAP packet.
 801  */
 802 static char *ChapCodenames[] = {
 803     "Challenge", "Response", "Success", "Failure"
 804 };
 805
 806 static int
 807 ChapPrintPkt(p, plen, printer, arg)
 808     u_char *p;
 809     int plen;
 810     void (*printer) __P((void *, char *, ...));
 811     void *arg;
 812 {
 813     int code, id, len;
 814     int clen, nlen;
 815     u_char x;
 816
 817     if (plen < CHAP_HEADERLEN)
 818         return 0;
 819     GETCHAR(code, p);
 820     GETCHAR(id, p);
 821     GETSHORT(len, p);
 822     if (len < CHAP_HEADERLEN || len > plen)
 823         return 0;
 824
 825     if (code >= 1 && code <= sizeof(ChapCodenames) / sizeof(char *))
 826         printer(arg, " %s", ChapCodenames[code-1]);
 827     else
 828         printer(arg, " code=0x%x", code);
 829     printer(arg, " id=0x%x", id);
 830     len -= CHAP_HEADERLEN;
 831     switch (code) {
 832     case CHAP_CHALLENGE:
 833     case CHAP_RESPONSE:
 834         if (len < 1)
 835             break;
 836         clen = p[0];
 837         if (len < clen + 1)
 838             break;
 839         ++p;
 840         nlen = len - clen - 1;
 841         printer(arg, " <");
 842         for (; clen > 0; --clen) {
 843             GETCHAR(x, p);
 844             printer(arg, "%.2x", x);
 845         }
 846         printer(arg, ">, name = ");
 847         print_string((char *)p, nlen, printer, arg);
 848         break;
 849     case CHAP_FAILURE:
 850     case CHAP_SUCCESS:
 851         printer(arg, " ");
 852         print_string((char *)p, len, printer, arg);
 853         break;
 854     default:
 855         for (clen = len; clen > 0; --clen) {
 856             GETCHAR(x, p);
 857             printer(arg, " %.2x", x);
 858         }
 859     }
 860
 861     return len + CHAP_HEADERLEN;
 862 }