pppd/chap.c

   1 /*
   2  * chap.c - Crytographic Handshake Authentication Protocol.
   3  *
   4  * Copyright (c) 1991 Gregory M. Christy.
   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 Gregory M. Christy.  The name of the author may not be used to
  13  * endorse or promote products derived from this software without
  14  * specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  18  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  19  */
  20
  21 #ifndef lint
  22 static char rcsid[] = "$Id: chap.c,v 1.4 1994/09/21 06:47:37 paulus Exp $";
  23 #endif
  24
  25 /*
  26  * TODO:
  27  */
  28
  29 #include <stdio.h>
  30 #include <sys/types.h>
  31 #include <sys/time.h>
  32 #include <syslog.h>
  33
  34 #include "pppd.h"
  35 #include "chap.h"
  36 #include "md5.h"
  37
  38 chap_state chap[N_PPP];         /* CHAP state; one for each unit */
  39
  40 static void ChapChallengeTimeout __P((caddr_t));
  41 static void ChapResponseTimeout __P((caddr_t));
  42 static void ChapReceiveChallenge __P((chap_state *, u_char *, int, int));
  43 static void ChapReceiveResponse __P((chap_state *, u_char *, int, int));
  44 static void ChapReceiveSuccess __P((chap_state *, u_char *, int, int));
  45 static void ChapReceiveFailure __P((chap_state *, u_char *, int, int));
  46 static void ChapSendStatus __P((chap_state *, int));
  47 static void ChapSendChallenge __P((chap_state *));
  48 static void ChapSendResponse __P((chap_state *));
  49 static void ChapGenChallenge __P((chap_state *));
  50
  51 extern double drand48 __P((void));
  52 extern void srand48 __P((long));
  53
  54 /*
  55  * ChapInit - Initialize a CHAP unit.
  56  */
  57 void
  58 ChapInit(unit)
  59     int unit;
  60 {
  61     chap_state *cstate = &chap[unit];
  62
  63     BZERO(cstate, sizeof(*cstate));
  64     cstate->unit = unit;
  65     cstate->clientstate = CHAPCS_INITIAL;
  66     cstate->serverstate = CHAPSS_INITIAL;
  67     cstate->timeouttime = CHAP_DEFTIMEOUT;
  68     cstate->max_transmits = CHAP_DEFTRANSMITS;
  69     srand48((long) time(NULL)); /* joggle random number generator */
  70 }
  71
  72
  73 /*
  74  * ChapAuthWithPeer - Authenticate us with our peer (start client).
  75  *
  76  */
  77 void
  78 ChapAuthWithPeer(unit, our_name, digest)
  79     int unit;
  80     char *our_name;
  81     int digest;
  82 {
  83     chap_state *cstate = &chap[unit];
  84
  85     cstate->resp_name = our_name;
  86     cstate->resp_type = digest;
  87
  88     if (cstate->clientstate == CHAPCS_INITIAL ||
  89         cstate->clientstate == CHAPCS_PENDING) {
  90         /* lower layer isn't up - wait until later */
  91         cstate->clientstate = CHAPCS_PENDING;
  92         return;
  93     }
  94
  95     /*
  96      * We get here as a result of LCP coming up.
  97      * So even if CHAP was open before, we will
  98      * have to re-authenticate ourselves.
  99      */
 100     cstate->clientstate = CHAPCS_LISTEN;
 101 }
 102
 103
 104 /*
 105  * ChapAuthPeer - Authenticate our peer (start server).
 106  */
 107 void
 108 ChapAuthPeer(unit, our_name, digest)
 109     int unit;
 110     char *our_name;
 111     int digest;
 112 {
 113     chap_state *cstate = &chap[unit];
 114
 115     cstate->chal_name = our_name;
 116     cstate->chal_type = digest;
 117
 118     if (cstate->serverstate == CHAPSS_INITIAL ||
 119         cstate->serverstate == CHAPSS_PENDING) {
 120         /* lower layer isn't up - wait until later */
 121         cstate->serverstate = CHAPSS_PENDING;
 122         return;
 123     }
 124
 125     ChapGenChallenge(cstate);
 126     ChapSendChallenge(cstate);          /* crank it up dude! */
 127     cstate->serverstate = CHAPSS_INITIAL_CHAL;
 128 }
 129
 130
 131 /*
 132  * ChapChallengeTimeout - Timeout expired on sending challenge.
 133  */
 134 static void
 135 ChapChallengeTimeout(arg)
 136     caddr_t arg;
 137 {
 138     chap_state *cstate = (chap_state *) arg;
 139
 140     /* if we aren't sending challenges, don't worry.  then again we */
 141     /* probably shouldn't be here either */
 142     if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
 143         cstate->serverstate != CHAPSS_RECHALLENGE)
 144         return;
 145
 146     if (cstate->chal_transmits >= cstate->max_transmits) {
 147         /* give up on peer */
 148         syslog(LOG_ERR, "Peer failed to respond to CHAP challenge");
 149         cstate->serverstate = CHAPSS_BADAUTH;
 150         auth_peer_fail(cstate->unit, PPP_CHAP);
 151         return;
 152     }
 153
 154     ChapSendChallenge(cstate);          /* Re-send challenge */
 155 }
 156
 157
 158 /*
 159  * ChapResponseTimeout - Timeout expired on sending response.
 160  */
 161 static void
 162 ChapResponseTimeout(arg)
 163     caddr_t arg;
 164 {
 165     chap_state *cstate = (chap_state *) arg;
 166
 167     /* if we aren't sending a response, don't worry. */
 168     if (cstate->clientstate != CHAPCS_RESPONSE)
 169         return;
 170
 171     ChapSendResponse(cstate);           /* re-send response */
 172 }
 173
 174
 175 /*
 176  * ChapRechallenge - Time to challenge the peer again.
 177  */
 178 static void
 179 ChapRechallenge(arg)
 180     caddr_t arg;
 181 {
 182     chap_state *cstate = (chap_state *) arg;
 183
 184     /* if we aren't sending a response, don't worry. */
 185     if (cstate->serverstate != CHAPSS_OPEN)
 186         return;
 187
 188     ChapGenChallenge(cstate);
 189     ChapSendChallenge(cstate);
 190     cstate->serverstate = CHAPSS_RECHALLENGE;
 191
 192     if (cstate->chal_interval != 0)
 193         TIMEOUT(ChapRechallenge, (caddr_t) cstate, cstate->chal_interval);
 194 }
 195
 196
 197 /*
 198  * ChapLowerUp - The lower layer is up.
 199  *
 200  * Start up if we have pending requests.
 201  */
 202 void
 203 ChapLowerUp(unit)
 204     int unit;
 205 {
 206     chap_state *cstate = &chap[unit];
 207
 208     if (cstate->clientstate == CHAPCS_INITIAL)
 209         cstate->clientstate = CHAPCS_CLOSED;
 210     else if (cstate->clientstate == CHAPCS_PENDING)
 211         cstate->clientstate = CHAPCS_LISTEN;
 212
 213     if (cstate->serverstate == CHAPSS_INITIAL)
 214         cstate->serverstate = CHAPSS_CLOSED;
 215     else if (cstate->serverstate == CHAPSS_PENDING) {
 216         ChapGenChallenge(cstate);
 217         ChapSendChallenge(cstate);
 218         cstate->serverstate = CHAPSS_INITIAL_CHAL;
 219     }
 220 }
 221
 222
 223 /*
 224  * ChapLowerDown - The lower layer is down.
 225  *
 226  * Cancel all timeouts.
 227  */
 228 void
 229 ChapLowerDown(unit)
 230     int unit;
 231 {
 232     chap_state *cstate = &chap[unit];
 233
 234     /* Timeout(s) pending?  Cancel if so. */
 235     if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
 236         cstate->serverstate == CHAPSS_RECHALLENGE)
 237         UNTIMEOUT(ChapChallengeTimeout, (caddr_t) cstate);
 238     else if (cstate->serverstate == CHAPSS_OPEN
 239              && cstate->chal_interval != 0)
 240         UNTIMEOUT(ChapRechallenge, (caddr_t) cstate);
 241     if (cstate->clientstate == CHAPCS_RESPONSE)
 242         UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 243
 244     cstate->clientstate = CHAPCS_INITIAL;
 245     cstate->serverstate = CHAPSS_INITIAL;
 246 }
 247
 248
 249 /*
 250  * ChapProtocolReject - Peer doesn't grok CHAP.
 251  */
 252 void
 253 ChapProtocolReject(unit)
 254     int unit;
 255 {
 256     chap_state *cstate = &chap[unit];
 257
 258     if (cstate->serverstate != CHAPSS_INITIAL &&
 259         cstate->serverstate != CHAPSS_CLOSED)
 260         auth_peer_fail(unit, PPP_CHAP);
 261     if (cstate->clientstate != CHAPCS_INITIAL &&
 262         cstate->clientstate != CHAPCS_CLOSED)
 263         auth_withpeer_fail(unit, PPP_CHAP);
 264     ChapLowerDown(unit);                /* shutdown chap */
 265 }
 266
 267
 268 /*
 269  * ChapInput - Input CHAP packet.
 270  */
 271 void
 272 ChapInput(unit, inpacket, packet_len)
 273     int unit;
 274     u_char *inpacket;
 275     int packet_len;
 276 {
 277     chap_state *cstate = &chap[unit];
 278     u_char *inp;
 279     u_char code, id;
 280     int len;
 281
 282     /*
 283      * Parse header (code, id and length).
 284      * If packet too short, drop it.
 285      */
 286     inp = inpacket;
 287     if (packet_len < CHAP_HEADERLEN) {
 288         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short header."));
 289         return;
 290     }
 291     GETCHAR(code, inp);
 292     GETCHAR(id, inp);
 293     GETSHORT(len, inp);
 294     if (len < CHAP_HEADERLEN) {
 295         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd illegal length."));
 296         return;
 297     }
 298     if (len > packet_len) {
 299         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short packet."));
 300         return;
 301     }
 302     len -= CHAP_HEADERLEN;
 303
 304     /*
 305      * Action depends on code (as in fact it usually does :-).
 306      */
 307     switch (code) {
 308     case CHAP_CHALLENGE:
 309         ChapReceiveChallenge(cstate, inp, id, len);
 310         break;
 311
 312     case CHAP_RESPONSE:
 313         ChapReceiveResponse(cstate, inp, id, len);
 314         break;
 315
 316     case CHAP_FAILURE:
 317         ChapReceiveFailure(cstate, inp, id, len);
 318         break;
 319
 320     case CHAP_SUCCESS:
 321         ChapReceiveSuccess(cstate, inp, id, len);
 322         break;
 323
 324     default:                            /* Need code reject? */
 325         syslog(LOG_WARNING, "Unknown CHAP code (%d) received.", code);
 326         break;
 327     }
 328 }
 329
 330
 331 /*
 332  * ChapReceiveChallenge - Receive Challenge and send Response.
 333  */
 334 static void
 335 ChapReceiveChallenge(cstate, inp, id, len)
 336     chap_state *cstate;
 337     u_char *inp;
 338     int id;
 339     int len;
 340 {
 341     int rchallenge_len;
 342     u_char *rchallenge;
 343     int secret_len;
 344     char secret[MAXSECRETLEN];
 345     char rhostname[256];
 346     MD5_CTX mdContext;
 347
 348     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: Rcvd id %d.", id));
 349     if (cstate->clientstate == CHAPCS_CLOSED ||
 350         cstate->clientstate == CHAPCS_PENDING) {
 351         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: in state %d",
 352                    cstate->clientstate));
 353         return;
 354     }
 355
 356     if (len < 2) {
 357         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 358         return;
 359     }
 360
 361     GETCHAR(rchallenge_len, inp);
 362     len -= sizeof (u_char) + rchallenge_len;    /* now name field length */
 363     if (len < 0) {
 364         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 365         return;
 366     }
 367     rchallenge = inp;
 368     INCPTR(rchallenge_len, inp);
 369
 370     if (len >= sizeof(rhostname))
 371         len = sizeof(rhostname) - 1;
 372     BCOPY(inp, rhostname, len);
 373     rhostname[len] = '\000';
 374
 375     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: received name field: %s",
 376                rhostname));
 377
 378     /* get secret for authenticating ourselves with the specified host */
 379     if (!get_secret(cstate->unit, cstate->resp_name, rhostname,
 380                     secret, &secret_len, 0)) {
 381         secret_len = 0;         /* assume null secret if can't find one */
 382         syslog(LOG_WARNING, "No CHAP secret found for authenticating us to %s",
 383                rhostname);
 384     }
 385
 386     /* cancel response send timeout if necessary */
 387     if (cstate->clientstate == CHAPCS_RESPONSE)
 388         UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 389
 390     cstate->resp_id = id;
 391     cstate->resp_transmits = 0;
 392
 393     /*  generate MD based on negotiated type */
 394     switch (cstate->resp_type) {
 395
 396     case CHAP_DIGEST_MD5:               /* only MD5 is defined for now */
 397         MD5Init(&mdContext);
 398         MD5Update(&mdContext, &cstate->resp_id, 1);
 399         MD5Update(&mdContext, secret, secret_len);
 400         MD5Update(&mdContext, rchallenge, rchallenge_len);
 401         MD5Final(&mdContext);
 402         BCOPY(mdContext.digest, cstate->response, MD5_SIGNATURE_SIZE);
 403         cstate->resp_length = MD5_SIGNATURE_SIZE;
 404         break;
 405
 406     default:
 407         CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->resp_type));
 408         return;
 409     }
 410
 411     ChapSendResponse(cstate);
 412 }
 413
 414
 415 /*
 416  * ChapReceiveResponse - Receive and process response.
 417  */
 418 static void
 419 ChapReceiveResponse(cstate, inp, id, len)
 420     chap_state *cstate;
 421     u_char *inp;
 422     int id;
 423     int len;
 424 {
 425     u_char *remmd, remmd_len;
 426     int secret_len, old_state;
 427     int code;
 428     char rhostname[256];
 429     u_char buf[256];
 430     MD5_CTX mdContext;
 431     u_char msg[256];
 432     char secret[MAXSECRETLEN];
 433
 434     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: Rcvd id %d.", id));
 435
 436     if (cstate->serverstate == CHAPSS_CLOSED ||
 437         cstate->serverstate == CHAPSS_PENDING) {
 438         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: in state %d",
 439                    cstate->serverstate));
 440         return;
 441     }
 442
 443     if (id != cstate->chal_id)
 444         return;                 /* doesn't match ID of last challenge */
 445
 446     /*
 447      * If we have received a duplicate or bogus Response,
 448      * we have to send the same answer (Success/Failure)
 449      * as we did for the first Response we saw.
 450      */
 451     if (cstate->serverstate == CHAPSS_OPEN) {
 452         ChapSendStatus(cstate, CHAP_SUCCESS);
 453         return;
 454     }
 455     if (cstate->serverstate == CHAPSS_BADAUTH) {
 456         ChapSendStatus(cstate, CHAP_FAILURE);
 457         return;
 458     }
 459
 460     if (len < 2) {
 461         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 462         return;
 463     }
 464     GETCHAR(remmd_len, inp);            /* get length of MD */
 465     remmd = inp;                        /* get pointer to MD */
 466     INCPTR(remmd_len, inp);
 467
 468     len -= sizeof (u_char) + remmd_len;
 469     if (len < 0) {
 470         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 471         return;
 472     }
 473
 474     UNTIMEOUT(ChapChallengeTimeout, (caddr_t) cstate);
 475
 476     if (len >= sizeof(rhostname))
 477         len = sizeof(rhostname) - 1;
 478     BCOPY(inp, rhostname, len);
 479     rhostname[len] = '\000';
 480
 481     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: received name field: %s",
 482                rhostname));
 483
 484     /*
 485      * Get secret for authenticating them with us,
 486      * do the hash ourselves, and compare the result.
 487      */
 488     code = CHAP_FAILURE;
 489     if (!get_secret(cstate->unit, rhostname, cstate->chal_name,
 490                    secret, &secret_len, 1)) {
 491         syslog(LOG_WARNING, "No CHAP secret found for authenticating %s",
 492                rhostname);
 493     } else {
 494
 495         /*  generate MD based on negotiated type */
 496         switch (cstate->chal_type) {
 497
 498         case CHAP_DIGEST_MD5:           /* only MD5 is defined for now */
 499             if (remmd_len != MD5_SIGNATURE_SIZE)
 500                 break;                  /* it's not even the right length */
 501             MD5Init(&mdContext);
 502             MD5Update(&mdContext, &cstate->chal_id, 1);
 503             MD5Update(&mdContext, secret, secret_len);
 504             MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
 505             MD5Final(&mdContext);
 506
 507             /* compare local and remote MDs and send the appropriate status */
 508             if (bcmp (mdContext.digest, remmd, MD5_SIGNATURE_SIZE) == 0)
 509                 code = CHAP_SUCCESS;    /* they are the same! */
 510             break;
 511
 512         default:
 513             CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->chal_type));
 514         }
 515     }
 516
 517     ChapSendStatus(cstate, code);
 518
 519     if (code == CHAP_SUCCESS) {
 520         old_state = cstate->serverstate;
 521         cstate->serverstate = CHAPSS_OPEN;
 522         if (old_state == CHAPSS_INITIAL_CHAL) {
 523             auth_peer_success(cstate->unit, PPP_CHAP);
 524         }
 525         if (cstate->chal_interval != 0)
 526             TIMEOUT(ChapRechallenge, (caddr_t) cstate, cstate->chal_interval);
 527
 528     } else {
 529         syslog(LOG_ERR, "CHAP peer authentication failed");
 530         cstate->serverstate = CHAPSS_BADAUTH;
 531         auth_peer_fail(cstate->unit, PPP_CHAP);
 532     }
 533 }
 534
 535 /*
 536  * ChapReceiveSuccess - Receive Success
 537  */
 538 static void
 539 ChapReceiveSuccess(cstate, inp, id, len)
 540     chap_state *cstate;
 541     u_char *inp;
 542     u_char id;
 543     int len;
 544 {
 545
 546     CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: Rcvd id %d.", id));
 547
 548     if (cstate->clientstate == CHAPCS_OPEN)
 549         /* presumably an answer to a duplicate response */
 550         return;
 551
 552     if (cstate->clientstate != CHAPCS_RESPONSE) {
 553         /* don't know what this is */
 554         CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: in state %d\n",
 555                    cstate->clientstate));
 556         return;
 557     }
 558
 559     UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 560
 561     /*
 562      * Print message.
 563      */
 564     if (len > 0)
 565         PRINTMSG(inp, len);
 566
 567     cstate->clientstate = CHAPCS_OPEN;
 568
 569     auth_withpeer_success(cstate->unit, PPP_CHAP);
 570 }
 571
 572
 573 /*
 574  * ChapReceiveFailure - Receive failure.
 575  */
 576 static void
 577 ChapReceiveFailure(cstate, inp, id, len)
 578     chap_state *cstate;
 579     u_char *inp;
 580     u_char id;
 581     int len;
 582 {
 583     u_char msglen;
 584     u_char *msg;
 585
 586     CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: Rcvd id %d.", id));
 587
 588     if (cstate->clientstate != CHAPCS_RESPONSE) {
 589         /* don't know what this is */
 590         CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: in state %d\n",
 591                    cstate->clientstate));
 592         return;
 593     }
 594
 595     UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 596
 597     /*
 598      * Print message.
 599      */
 600     if (len > 0)
 601         PRINTMSG(inp, len);
 602
 603     syslog(LOG_ERR, "CHAP authentication failed");
 604     auth_withpeer_fail(cstate->unit, PPP_CHAP);
 605 }
 606
 607
 608 /*
 609  * ChapSendChallenge - Send an Authenticate challenge.
 610  */
 611 static void
 612 ChapSendChallenge(cstate)
 613     chap_state *cstate;
 614 {
 615     u_char *outp;
 616     int chal_len, name_len;
 617     int outlen;
 618
 619     chal_len = cstate->chal_len;
 620     name_len = strlen(cstate->chal_name);
 621     outlen = CHAP_HEADERLEN + sizeof (u_char) + chal_len + name_len;
 622     outp = outpacket_buf;
 623
 624     MAKEHEADER(outp, PPP_CHAP);         /* paste in a CHAP header */
 625
 626     PUTCHAR(CHAP_CHALLENGE, outp);
 627     PUTCHAR(cstate->chal_id, outp);
 628     PUTSHORT(outlen, outp);
 629
 630     PUTCHAR(chal_len, outp);            /* put length of challenge */
 631     BCOPY(cstate->challenge, outp, chal_len);
 632     INCPTR(chal_len, outp);
 633
 634     BCOPY(cstate->chal_name, outp, name_len);   /* append hostname */
 635
 636     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 637
 638     CHAPDEBUG((LOG_INFO, "ChapSendChallenge: Sent id %d.", cstate->chal_id));
 639
 640     TIMEOUT(ChapChallengeTimeout, (caddr_t) cstate, cstate->timeouttime);
 641     ++cstate->chal_transmits;
 642 }
 643
 644
 645 /*
 646  * ChapSendStatus - Send a status response (ack or nak).
 647  */
 648 static void
 649 ChapSendStatus(cstate, code)
 650     chap_state *cstate;
 651     int code;
 652 {
 653     u_char *outp;
 654     int outlen, msglen;
 655     char msg[256];
 656
 657     if (code == CHAP_SUCCESS)
 658         sprintf(msg, "Welcome to %s.", hostname);
 659     else
 660         sprintf(msg, "I don't like you.  Go 'way.");
 661     msglen = strlen(msg);
 662
 663     outlen = CHAP_HEADERLEN + msglen;
 664     outp = outpacket_buf;
 665
 666     MAKEHEADER(outp, PPP_CHAP); /* paste in a header */
 667
 668     PUTCHAR(code, outp);
 669     PUTCHAR(cstate->chal_id, outp);
 670     PUTSHORT(outlen, outp);
 671     BCOPY(msg, outp, msglen);
 672     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 673
 674     CHAPDEBUG((LOG_INFO, "ChapSendStatus: Sent code %d, id %d.", code,
 675                cstate->chal_id));
 676 }
 677
 678 /*
 679  * ChapGenChallenge is used to generate a pseudo-random challenge string of
 680  * a pseudo-random length between min_len and max_len.  The challenge
 681  * string and its length are stored in *cstate, and various other fields of
 682  * *cstate are initialized.
 683  */
 684
 685 static void
 686 ChapGenChallenge(cstate)
 687     chap_state *cstate;
 688 {
 689     int chal_len;
 690     u_char *ptr = cstate->challenge;
 691     unsigned int i;
 692
 693     /* pick a random challenge length between MIN_CHALLENGE_LENGTH and
 694        MAX_CHALLENGE_LENGTH */
 695     chal_len =  (unsigned) ((drand48() *
 696                              (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
 697                             MIN_CHALLENGE_LENGTH);
 698     cstate->chal_len = chal_len;
 699     cstate->chal_id = ++cstate->id;
 700     cstate->chal_transmits = 0;
 701
 702     /* generate a random string */
 703     for (i = 0; i < chal_len; i++ )
 704         *ptr++ = (char) (drand48() * 0xff);
 705 }
 706
 707 /*
 708  * ChapSendResponse - send a response packet with values as specified
 709  * in *cstate.
 710  */
 711 /* ARGSUSED */
 712 static void
 713 ChapSendResponse(cstate)
 714     chap_state *cstate;
 715 {
 716     u_char *outp;
 717     int outlen, md_len, name_len;
 718
 719     md_len = cstate->resp_length;
 720     name_len = strlen(cstate->resp_name);
 721     outlen = CHAP_HEADERLEN + sizeof (u_char) + md_len + name_len;
 722     outp = outpacket_buf;
 723
 724     MAKEHEADER(outp, PPP_CHAP);
 725
 726     PUTCHAR(CHAP_RESPONSE, outp);       /* we are a response */
 727     PUTCHAR(cstate->resp_id, outp);     /* copy id from challenge packet */
 728     PUTSHORT(outlen, outp);             /* packet length */
 729
 730     PUTCHAR(md_len, outp);              /* length of MD */
 731     BCOPY(cstate->response, outp, md_len);      /* copy MD to buffer */
 732     INCPTR(md_len, outp);
 733
 734     BCOPY(cstate->resp_name, outp, name_len); /* append our name */
 735
 736     /* send the packet */
 737     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 738
 739     cstate->clientstate = CHAPCS_RESPONSE;
 740     TIMEOUT(ChapResponseTimeout, (caddr_t) cstate, cstate->timeouttime);
 741     ++cstate->resp_transmits;
 742 }
 743
 744 /*
 745  * ChapPrintPkt - print the contents of a CHAP packet.
 746  */
 747 char *ChapCodenames[] = {
 748     "Challenge", "Response", "Success", "Failure"
 749 };
 750
 751 int
 752 ChapPrintPkt(p, plen, printer, arg)
 753     u_char *p;
 754     int plen;
 755     void (*printer) __P((void *, char *, ...));
 756     void *arg;
 757 {
 758     int code, id, len;
 759     int clen, nlen;
 760     u_char x;
 761
 762     if (plen < CHAP_HEADERLEN)
 763         return 0;
 764     GETCHAR(code, p);
 765     GETCHAR(id, p);
 766     GETSHORT(len, p);
 767     if (len < CHAP_HEADERLEN || len > plen)
 768         return 0;
 769
 770     if (code >= 1 && code <= sizeof(ChapCodenames) / sizeof(char *))
 771         printer(arg, " %s", ChapCodenames[code-1]);
 772     else
 773         printer(arg, " code=0x%x", code);
 774     printer(arg, " id=0x%x", id);
 775     len -= CHAP_HEADERLEN;
 776     switch (code) {
 777     case CHAP_CHALLENGE:
 778     case CHAP_RESPONSE:
 779         if (len < 1)
 780             break;
 781         clen = p[0];
 782         if (len < clen + 1)
 783             break;
 784         ++p;
 785         nlen = len - clen - 1;
 786         printer(arg, " <");
 787         for (; clen > 0; --clen) {
 788             GETCHAR(x, p);
 789             printer(arg, "%.2x", x);
 790         }
 791         printer(arg, ">, name = ");
 792         print_string((char *)p, nlen, printer, arg);
 793         break;
 794     case CHAP_FAILURE:
 795     case CHAP_SUCCESS:
 796         printer(arg, " ");
 797         print_string((char *)p, len, printer, arg);
 798         break;
 799     default:
 800         for (clen = len; clen > 0; --clen) {
 801             GETCHAR(x, p);
 802             printer(arg, " %.2x", x);
 803         }
 804     }
 805
 806     return len + CHAP_HEADERLEN;
 807 }
 808
 809 #ifdef NO_DRAND48
 810
 811 double drand48()
 812 {
 813   return (double)random() / (double)0x7fffffffL; /* 2**31-1 */
 814 }
 815
 816 void srand48(seedval)
 817 long seedval;
 818 {
 819   srand((int)seedval);
 820 }
 821
 822 #endif