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 1.1 1993/11/11 03:54:25 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 "ppp.h"
  35 #include "pppd.h"
  36 #include "chap.h"
  37 #include "md5.h"
  38
  39 chap_state chap[NPPP];          /* CHAP state; one for each unit */
  40
  41 static void ChapChallengeTimeout __ARGS((caddr_t));
  42 static void ChapResponseTimeout __ARGS((caddr_t));
  43 static void ChapReceiveChallenge __ARGS((chap_state *, u_char *, int, int));
  44 static void ChapReceiveResponse __ARGS((chap_state *, u_char *, int, int));
  45 static void ChapReceiveSuccess __ARGS((chap_state *, u_char *, int, int));
  46 static void ChapReceiveFailure __ARGS((chap_state *, u_char *, int, int));
  47 static void ChapSendStatus __ARGS((chap_state *, int));
  48 static void ChapSendChallenge __ARGS((chap_state *));
  49 static void ChapSendResponse __ARGS((chap_state *));
  50 static void ChapGenChallenge __ARGS((chap_state *));
  51
  52 extern double drand48 __ARGS((void));
  53 extern void srand48 __ARGS((long));
  54
  55 /*
  56  * ChapInit - Initialize a CHAP unit.
  57  */
  58 void
  59 ChapInit(unit)
  60     int unit;
  61 {
  62     chap_state *cstate = &chap[unit];
  63
  64     BZERO(cstate, sizeof(*cstate));
  65     cstate->unit = unit;
  66     cstate->clientstate = CHAPCS_INITIAL;
  67     cstate->serverstate = CHAPSS_INITIAL;
  68     cstate->timeouttime = CHAP_DEFTIMEOUT;
  69     cstate->max_transmits = CHAP_DEFTRANSMITS;
  70     srand48((long) time(NULL)); /* joggle random number generator */
  71 }
  72
  73
  74 /*
  75  * ChapAuthWithPeer - Authenticate us with our peer (start client).
  76  *
  77  */
  78 void
  79 ChapAuthWithPeer(unit, our_name, digest)
  80     int unit;
  81     char *our_name;
  82     int digest;
  83 {
  84     chap_state *cstate = &chap[unit];
  85
  86     cstate->resp_name = our_name;
  87     cstate->resp_type = digest;
  88
  89     if (cstate->clientstate == CHAPCS_INITIAL ||
  90         cstate->clientstate == CHAPCS_PENDING) {
  91         /* lower layer isn't up - wait until later */
  92         cstate->clientstate = CHAPCS_PENDING;
  93         return;
  94     }
  95
  96     /*
  97      * We get here as a result of LCP coming up.
  98      * So even if CHAP was open before, we will
  99      * have to re-authenticate ourselves.
 100      */
 101     cstate->clientstate = CHAPCS_LISTEN;
 102 }
 103
 104
 105 /*
 106  * ChapAuthPeer - Authenticate our peer (start server).
 107  */
 108 void
 109 ChapAuthPeer(unit, our_name, digest)
 110     int unit;
 111     char *our_name;
 112     int digest;
 113 {
 114     chap_state *cstate = &chap[unit];
 115
 116     cstate->chal_name = our_name;
 117     cstate->chal_type = digest;
 118
 119     if (cstate->serverstate == CHAPSS_INITIAL ||
 120         cstate->serverstate == CHAPSS_PENDING) {
 121         /* lower layer isn't up - wait until later */
 122         cstate->serverstate = CHAPSS_PENDING;
 123         return;
 124     }
 125
 126     ChapGenChallenge(cstate);
 127     ChapSendChallenge(cstate);          /* crank it up dude! */
 128     cstate->serverstate = CHAPSS_INITIAL_CHAL;
 129 }
 130
 131
 132 /*
 133  * ChapChallengeTimeout - Timeout expired on sending challenge.
 134  */
 135 static void
 136 ChapChallengeTimeout(arg)
 137     caddr_t arg;
 138 {
 139     chap_state *cstate = (chap_state *) arg;
 140
 141     /* if we aren't sending challenges, don't worry.  then again we */
 142     /* probably shouldn't be here either */
 143     if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
 144         cstate->serverstate != CHAPSS_RECHALLENGE)
 145         return;
 146
 147     if (cstate->chal_transmits >= cstate->max_transmits) {
 148         /* give up on peer */
 149         syslog(LOG_ERR, "Peer failed to respond to CHAP challenge");
 150         cstate->serverstate = CHAPSS_BADAUTH;
 151         auth_peer_fail(cstate->unit, CHAP);
 152         return;
 153     }
 154
 155     ChapSendChallenge(cstate);          /* Re-send challenge */
 156 }
 157
 158
 159 /*
 160  * ChapResponseTimeout - Timeout expired on sending response.
 161  */
 162 static void
 163 ChapResponseTimeout(arg)
 164     caddr_t arg;
 165 {
 166     chap_state *cstate = (chap_state *) arg;
 167
 168     /* if we aren't sending a response, don't worry. */
 169     if (cstate->clientstate != CHAPCS_RESPONSE)
 170         return;
 171
 172     ChapSendResponse(cstate);           /* re-send response */
 173 }
 174
 175
 176 /*
 177  * ChapRechallenge - Time to challenge the peer again.
 178  */
 179 static void
 180 ChapRechallenge(arg)
 181     caddr_t arg;
 182 {
 183     chap_state *cstate = (chap_state *) arg;
 184
 185     /* if we aren't sending a response, don't worry. */
 186     if (cstate->serverstate != CHAPSS_OPEN)
 187         return;
 188
 189     ChapGenChallenge(cstate);
 190     ChapSendChallenge(cstate);
 191     cstate->serverstate = CHAPSS_RECHALLENGE;
 192
 193     if (cstate->chal_interval != 0)
 194         TIMEOUT(ChapRechallenge, (caddr_t) cstate, cstate->chal_interval);
 195 }
 196
 197
 198 /*
 199  * ChapLowerUp - The lower layer is up.
 200  *
 201  * Start up if we have pending requests.
 202  */
 203 void
 204 ChapLowerUp(unit)
 205     int unit;
 206 {
 207     chap_state *cstate = &chap[unit];
 208
 209     if (cstate->clientstate == CHAPCS_INITIAL)
 210         cstate->clientstate = CHAPCS_CLOSED;
 211     else if (cstate->clientstate == CHAPCS_PENDING)
 212         cstate->clientstate = CHAPCS_LISTEN;
 213
 214     if (cstate->serverstate == CHAPSS_INITIAL)
 215         cstate->serverstate = CHAPSS_CLOSED;
 216     else if (cstate->serverstate == CHAPSS_PENDING) {
 217         ChapGenChallenge(cstate);
 218         ChapSendChallenge(cstate);
 219         cstate->serverstate = CHAPSS_INITIAL_CHAL;
 220     }
 221 }
 222
 223
 224 /*
 225  * ChapLowerDown - The lower layer is down.
 226  *
 227  * Cancel all timeouts.
 228  */
 229 void
 230 ChapLowerDown(unit)
 231     int unit;
 232 {
 233     chap_state *cstate = &chap[unit];
 234
 235     /* Timeout(s) pending?  Cancel if so. */
 236     if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
 237         cstate->serverstate == CHAPSS_RECHALLENGE)
 238         UNTIMEOUT(ChapChallengeTimeout, (caddr_t) cstate);
 239     else if (cstate->serverstate == CHAPSS_OPEN
 240              && cstate->chal_interval != 0)
 241         UNTIMEOUT(ChapRechallenge, (caddr_t) cstate);
 242     if (cstate->clientstate == CHAPCS_RESPONSE)
 243         UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 244
 245     cstate->clientstate = CHAPCS_INITIAL;
 246     cstate->serverstate = CHAPSS_INITIAL;
 247 }
 248
 249
 250 /*
 251  * ChapProtocolReject - Peer doesn't grok CHAP.
 252  */
 253 void
 254 ChapProtocolReject(unit)
 255     int unit;
 256 {
 257     chap_state *cstate = &chap[unit];
 258
 259     if (cstate->serverstate != CHAPSS_INITIAL &&
 260         cstate->serverstate != CHAPSS_CLOSED)
 261         auth_peer_fail(unit, CHAP);
 262     if (cstate->clientstate != CHAPCS_INITIAL &&
 263         cstate->clientstate != CHAPCS_CLOSED)
 264         auth_withpeer_fail(unit, CHAP);
 265     ChapLowerDown(unit);                /* shutdown chap */
 266 }
 267
 268
 269 /*
 270  * ChapInput - Input CHAP packet.
 271  */
 272 void
 273 ChapInput(unit, inpacket, packet_len)
 274     int unit;
 275     u_char *inpacket;
 276     int packet_len;
 277 {
 278     chap_state *cstate = &chap[unit];
 279     u_char *inp;
 280     u_char code, id;
 281     int len;
 282
 283     /*
 284      * Parse header (code, id and length).
 285      * If packet too short, drop it.
 286      */
 287     inp = inpacket;
 288     if (packet_len < CHAP_HEADERLEN) {
 289         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short header."));
 290         return;
 291     }
 292     GETCHAR(code, inp);
 293     GETCHAR(id, inp);
 294     GETSHORT(len, inp);
 295     if (len < CHAP_HEADERLEN) {
 296         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd illegal length."));
 297         return;
 298     }
 299     if (len > packet_len) {
 300         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short packet."));
 301         return;
 302     }
 303     len -= CHAP_HEADERLEN;
 304
 305     /*
 306      * Action depends on code (as in fact it usually does :-).
 307      */
 308     switch (code) {
 309     case CHAP_CHALLENGE:
 310         ChapReceiveChallenge(cstate, inp, id, len);
 311         break;
 312
 313     case CHAP_RESPONSE:
 314         ChapReceiveResponse(cstate, inp, id, len);
 315         break;
 316
 317     case CHAP_FAILURE:
 318         ChapReceiveFailure(cstate, inp, id, len);
 319         break;
 320
 321     case CHAP_SUCCESS:
 322         ChapReceiveSuccess(cstate, inp, id, len);
 323         break;
 324
 325     default:                            /* Need code reject? */
 326         syslog(LOG_WARNING, "Unknown CHAP code (%d) received.", code);
 327         break;
 328     }
 329 }
 330
 331
 332 /*
 333  * ChapReceiveChallenge - Receive Challenge and send Response.
 334  */
 335 static void
 336 ChapReceiveChallenge(cstate, inp, id, len)
 337     chap_state *cstate;
 338     u_char *inp;
 339     int id;
 340     int len;
 341 {
 342     int rchallenge_len;
 343     u_char *rchallenge;
 344     int secret_len;
 345     char secret[MAXSECRETLEN];
 346     char rhostname[256];
 347     MD5_CTX mdContext;
 348
 349     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: Rcvd id %d.", id));
 350     if (cstate->clientstate == CHAPCS_CLOSED ||
 351         cstate->clientstate == CHAPCS_PENDING) {
 352         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: in state %d",
 353                    cstate->clientstate));
 354         return;
 355     }
 356
 357     if (len < 2) {
 358         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 359         return;
 360     }
 361
 362     GETCHAR(rchallenge_len, inp);
 363     len -= sizeof (u_char) + rchallenge_len;    /* now name field length */
 364     if (len < 0) {
 365         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 366         return;
 367     }
 368     rchallenge = inp;
 369     INCPTR(rchallenge_len, inp);
 370
 371     if (len >= sizeof(rhostname))
 372         len = sizeof(rhostname) - 1;
 373     BCOPY(inp, rhostname, len);
 374     rhostname[len] = '\000';
 375
 376     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: received name field: %s",
 377                rhostname));
 378
 379     /* get secret for authenticating ourselves with the specified host */
 380     if (!get_secret(cstate->unit, cstate->resp_name, rhostname,
 381                     secret, &secret_len, 0)) {
 382         secret_len = 0;         /* assume null secret if can't find one */
 383         syslog(LOG_WARNING, "No CHAP secret found for authenticating us to %s",
 384                rhostname);
 385     }
 386
 387     /* cancel response send timeout if necessary */
 388     if (cstate->clientstate == CHAPCS_RESPONSE)
 389         UNTIMEOUT(ChapResponseTimeout, (caddr_t) cstate);
 390
 391     cstate->resp_id = id;
 392     cstate->resp_transmits = 0;
 393
 394     /*  generate MD based on negotiated type */
 395     switch (cstate->resp_type) {
 396
 397     case CHAP_DIGEST_MD5:               /* only MD5 is defined for now */
 398         MD5Init(&mdContext);
 399         MD5Update(&mdContext, &cstate->resp_id, 1);
 400         MD5Update(&mdContext, secret, secret_len);
 401         MD5Update(&mdContext, rchallenge, rchallenge_len);
 402         MD5Final(&mdContext);
 403         BCOPY(mdContext.digest, cstate->response, MD5_SIGNATURE_SIZE);
 404         cstate->resp_length = MD5_SIGNATURE_SIZE;
 405         break;
 406
 407     default:
 408         CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->resp_type));
 409         return;
 410     }
 411
 412     ChapSendResponse(cstate);
 413 }
 414
 415
 416 /*
 417  * ChapReceiveResponse - Receive and process response.
 418  */
 419 static void
 420 ChapReceiveResponse(cstate, inp, id, len)
 421     chap_state *cstate;
 422     u_char *inp;
 423     int id;
 424     int len;
 425 {
 426     u_char *remmd, remmd_len;
 427     int secret_len, old_state;
 428     int code;
 429     char rhostname[256];
 430     u_char buf[256];
 431     MD5_CTX mdContext;
 432     u_char msg[256];
 433     char secret[MAXSECRETLEN];
 434
 435     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: Rcvd id %d.", id));
 436
 437     if (cstate->serverstate == CHAPSS_CLOSED ||
 438         cstate->serverstate == CHAPSS_PENDING) {
 439         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: in state %d",
 440                    cstate->serverstate));
 441         return;
 442     }
 443
 444     if (id != cstate->chal_id)
 445         return;                 /* doesn't match ID of last challenge */
 446
 447     /*
 448      * If we have received a duplicate or bogus Response,
 449      * we have to send the same answer (Success/Failure)
 450      * as we did for the first Response we saw.
 451      */
 452     if (cstate->serverstate == CHAPSS_OPEN) {
 453         ChapSendStatus(cstate, CHAP_SUCCESS);
 454         return;
 455     }
 456     if (cstate->serverstate == CHAPSS_BADAUTH) {
 457         ChapSendStatus(cstate, CHAP_FAILURE);
 458         return;
 459     }
 460
 461     if (len < 2) {
 462         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 463         return;
 464     }
 465     GETCHAR(remmd_len, inp);            /* get length of MD */
 466     remmd = inp;                        /* get pointer to MD */
 467     INCPTR(remmd_len, inp);
 468
 469     len -= sizeof (u_char) + remmd_len;
 470     if (len < 0) {
 471         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 472         return;
 473     }
 474
 475     UNTIMEOUT(ChapChallengeTimeout, (caddr_t) cstate);
 476
 477     if (len >= sizeof(rhostname))
 478         len = sizeof(rhostname) - 1;
 479     BCOPY(inp, rhostname, len);
 480     rhostname[len] = '\000';
 481
 482     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: received name field: %s",
 483                rhostname));
 484
 485     /*
 486      * Get secret for authenticating them with us,
 487      * do the hash ourselves, and compare the result.
 488      */
 489     code = CHAP_FAILURE;
 490     if (!get_secret(cstate->unit, rhostname, cstate->chal_name,
 491                    secret, &secret_len, 1)) {
 492         syslog(LOG_WARNING, "No CHAP secret found for authenticating %s",
 493                rhostname);
 494     } else {
 495
 496         /*  generate MD based on negotiated type */
 497         switch (cstate->chal_type) {
 498
 499         case CHAP_DIGEST_MD5:           /* only MD5 is defined for now */
 500             if (remmd_len != MD5_SIGNATURE_SIZE)
 501                 break;                  /* it's not even the right length */
 502             MD5Init(&mdContext);
 503             MD5Update(&mdContext, &cstate->chal_id, 1);
 504             MD5Update(&mdContext, secret, secret_len);
 505             MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
 506             MD5Final(&mdContext);
 507
 508             /* compare local and remote MDs and send the appropriate status */
 509             if (bcmp (mdContext.digest, remmd, MD5_SIGNATURE_SIZE) == 0)
 510                 code = CHAP_SUCCESS;    /* they are the same! */
 511             break;
 512
 513         default:
 514             CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->chal_type));
 515         }
 516     }
 517
 518     ChapSendStatus(cstate, code);
 519
 520     if (code == CHAP_SUCCESS) {
 521         old_state = cstate->serverstate;
 522         cstate->serverstate = CHAPSS_OPEN;
 523         if (old_state == CHAPSS_INITIAL_CHAL) {
 524             auth_peer_success(cstate->unit, CHAP);
 525         }
 526         if (cstate->chal_interval != 0)
 527             TIMEOUT(ChapRechallenge, (caddr_t) cstate, cstate->chal_interval);
 528
 529     } else {
 530         syslog(LOG_ERR, "CHAP peer authentication failed");
 531         cstate->serverstate = CHAPSS_BADAUTH;
 532         auth_peer_fail(cstate->unit, CHAP);
 533     }
 534 }
 535
 536 /*
 537  * ChapReceiveSuccess - Receive Success
 538  */
 539 static void
 540 ChapReceiveSuccess(cstate, inp, id, len)
 541     chap_state *cstate;
 542     u_char *inp;
 543     u_char id;
 544     int len;
 545 {
 546
 547     CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: Rcvd id %d.", id));
 548
 549     if (cstate->clientstate == CHAPCS_OPEN)
 550         /* presumably an answer to a duplicate response */
 551         return;
 552
 553     if (cstate->clientstate != CHAPCS_RESPONSE) {
 554         /* don't know what this is */
 555         CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: in state %d\n",
 556                    cstate->clientstate));
 557         return;
 558     }
 559
 560     /*
 561      * Print message.
 562      */
 563     if (len > 0)
 564         PRINTMSG(inp, len);
 565
 566     cstate->clientstate = CHAPCS_OPEN;
 567
 568     auth_withpeer_success(cstate->unit, CHAP);
 569 }
 570
 571
 572 /*
 573  * ChapReceiveFailure - Receive failure.
 574  */
 575 static void
 576 ChapReceiveFailure(cstate, inp, id, len)
 577     chap_state *cstate;
 578     u_char *inp;
 579     u_char id;
 580     int len;
 581 {
 582     u_char msglen;
 583     u_char *msg;
 584
 585     CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: Rcvd id %d.", id));
 586
 587     if (cstate->clientstate != CHAPCS_RESPONSE) {
 588         /* don't know what this is */
 589         CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: in state %d\n",
 590                    cstate->clientstate));
 591         return;
 592     }
 593
 594     /*
 595      * Print message.
 596      */
 597     if (len > 0)
 598         PRINTMSG(inp, len);
 599
 600     syslog(LOG_ERR, "CHAP authentication failed");
 601     auth_withpeer_fail(cstate->unit, CHAP);
 602 }
 603
 604
 605 /*
 606  * ChapSendChallenge - Send an Authenticate challenge.
 607  */
 608 static void
 609 ChapSendChallenge(cstate)
 610     chap_state *cstate;
 611 {
 612     u_char *outp;
 613     int chal_len, name_len;
 614     int outlen;
 615
 616     chal_len = cstate->chal_len;
 617     name_len = strlen(cstate->chal_name);
 618     outlen = CHAP_HEADERLEN + sizeof (u_char) + chal_len + name_len;
 619     outp = outpacket_buf;
 620
 621     MAKEHEADER(outp, CHAP);             /* paste in a CHAP header */
 622
 623     PUTCHAR(CHAP_CHALLENGE, outp);
 624     PUTCHAR(cstate->chal_id, outp);
 625     PUTSHORT(outlen, outp);
 626
 627     PUTCHAR(chal_len, outp);            /* put length of challenge */
 628     BCOPY(cstate->challenge, outp, chal_len);
 629     INCPTR(chal_len, outp);
 630
 631     BCOPY(cstate->chal_name, outp, name_len);   /* append hostname */
 632
 633     output(cstate->unit, outpacket_buf, outlen + DLLHEADERLEN);
 634
 635     CHAPDEBUG((LOG_INFO, "ChapSendChallenge: Sent id %d.", cstate->chal_id));
 636
 637     TIMEOUT(ChapChallengeTimeout, (caddr_t) cstate, cstate->timeouttime);
 638     ++cstate->chal_transmits;
 639 }
 640
 641
 642 /*
 643  * ChapSendStatus - Send a status response (ack or nak).
 644  */
 645 static void
 646 ChapSendStatus(cstate, code)
 647     chap_state *cstate;
 648     int code;
 649 {
 650     u_char *outp;
 651     int outlen, msglen;
 652     char msg[256];
 653
 654     if (code == CHAP_SUCCESS)
 655         sprintf(msg, "Welcome to %s.", hostname);
 656     else
 657         sprintf(msg, "I don't like you.  Go 'way.");
 658     msglen = strlen(msg);
 659
 660     outlen = CHAP_HEADERLEN + msglen;
 661     outp = outpacket_buf;
 662
 663     MAKEHEADER(outp, CHAP);     /* paste in a header */
 664
 665     PUTCHAR(code, outp);
 666     PUTCHAR(cstate->chal_id, outp);
 667     PUTSHORT(outlen, outp);
 668     BCOPY(msg, outp, msglen);
 669     output(cstate->unit, outpacket_buf, outlen + DLLHEADERLEN);
 670
 671     CHAPDEBUG((LOG_INFO, "ChapSendStatus: Sent code %d, id %d.", code,
 672                cstate->chal_id));
 673 }
 674
 675 /*
 676  * ChapGenChallenge is used to generate a pseudo-random challenge string of
 677  * a pseudo-random length between min_len and max_len.  The challenge
 678  * string and its length are stored in *cstate, and various other fields of
 679  * *cstate are initialized.
 680  */
 681
 682 static void
 683 ChapGenChallenge(cstate)
 684     chap_state *cstate;
 685 {
 686     int chal_len;
 687     u_char *ptr = cstate->challenge;
 688     unsigned int i;
 689
 690     /* pick a random challenge length between MIN_CHALLENGE_LENGTH and
 691        MAX_CHALLENGE_LENGTH */
 692     chal_len =  (unsigned) ((drand48() *
 693                              (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
 694                             MIN_CHALLENGE_LENGTH);
 695     cstate->chal_len = chal_len;
 696     cstate->chal_id = ++cstate->id;
 697     cstate->chal_transmits = 0;
 698
 699     /* generate a random string */
 700     for (i = 0; i < chal_len; i++ )
 701         *ptr++ = (char) (drand48() * 0xff);
 702 }
 703
 704 /*
 705  * ChapSendResponse - send a response packet with values as specified
 706  * in *cstate.
 707  */
 708 /* ARGSUSED */
 709 static void
 710 ChapSendResponse(cstate)
 711     chap_state *cstate;
 712 {
 713     u_char *outp;
 714     int outlen, md_len, name_len;
 715
 716     md_len = cstate->resp_length;
 717     name_len = strlen(cstate->resp_name);
 718     outlen = CHAP_HEADERLEN + sizeof (u_char) + md_len + name_len;
 719     outp = outpacket_buf;
 720
 721     MAKEHEADER(outp, CHAP);
 722
 723     PUTCHAR(CHAP_RESPONSE, outp);       /* we are a response */
 724     PUTCHAR(cstate->resp_id, outp);     /* copy id from challenge packet */
 725     PUTSHORT(outlen, outp);             /* packet length */
 726
 727     PUTCHAR(md_len, outp);              /* length of MD */
 728     BCOPY(cstate->response, outp, md_len);      /* copy MD to buffer */
 729     INCPTR(md_len, outp);
 730
 731     BCOPY(cstate->resp_name, outp, name_len); /* append our name */
 732
 733     /* send the packet */
 734     output(cstate->unit, outpacket_buf, outlen + DLLHEADERLEN);
 735
 736     cstate->clientstate = CHAPCS_RESPONSE;
 737     TIMEOUT(ChapResponseTimeout, (caddr_t) cstate, cstate->timeouttime);
 738     ++cstate->resp_transmits;
 739 }
 740
 741 #ifdef NO_DRAND48
 742
 743 double drand48()
 744 {
 745   return (double)random() / (double)0x7fffffffL; /* 2**31-1 */
 746 }
 747
 748 void srand48(seedval)
 749 long seedval;
 750 {
 751   srand((int)seedval);
 752 }
 753
 754 #endif