usr.sbin/pppd/chap.c

   1 /*
   2  * chap.c - Challenge Handshake Authentication Protocol.
   3  *
   4  * Copyright (c) 1993 The Australian National University.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms are permitted
   8  * provided that the above copyright notice and this paragraph are
   9  * duplicated in all such forms and that any documentation,
  10  * advertising materials, and other materials related to such
  11  * distribution and use acknowledge that the software was developed
  12  * by the Australian National University.  The name of the University
  13  * may not be used to endorse or promote products derived from this
  14  * software without specific prior written permission.
  15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  17  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  18  *
  19  * Copyright (c) 1991 Gregory M. Christy.
  20  * All rights reserved.
  21  *
  22  * Redistribution and use in source and binary forms are permitted
  23  * provided that the above copyright notice and this paragraph are
  24  * duplicated in all such forms and that any documentation,
  25  * advertising materials, and other materials related to such
  26  * distribution and use acknowledge that the software was developed
  27  * by Gregory M. Christy.  The name of the author may not be used to
  28  * endorse or promote products derived from this software without
  29  * specific prior written permission.
  30  *
  31  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  33  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  34  */
  35
  36 #ifndef lint
  37 static char rcsid[] = "$FreeBSD$";
  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 #include <md5.h>
  50
  51 #include "pppd.h"
  52 #include "chap.h"
  53 #include "md5.h"
  54 #ifdef CHAPMS
  55 #include "chap_ms.h"
  56 #endif
  57
  58 /*
  59  * Protocol entry points.
  60  */
  61 static void ChapInit(int);
  62 static void ChapLowerUp(int);
  63 static void ChapLowerDown(int);
  64 static void ChapInput(int, u_char *, int);
  65 static void ChapProtocolReject(int);
  66 static int  ChapPrintPkt(u_char *, int,
  67                               void (*)(void *, char *, ...), void *);
  68
  69 struct protent chap_protent = {
  70     PPP_CHAP,
  71     ChapInit,
  72     ChapInput,
  73     ChapProtocolReject,
  74     ChapLowerUp,
  75     ChapLowerDown,
  76     NULL,
  77     NULL,
  78     ChapPrintPkt,
  79     NULL,
  80     1,
  81     "CHAP",
  82     NULL,
  83     NULL,
  84     NULL
  85 };
  86
  87 chap_state chap[NUM_PPP];               /* CHAP state; one for each unit */
  88
  89 static void ChapChallengeTimeout(void *);
  90 static void ChapResponseTimeout(void *);
  91 static void ChapReceiveChallenge(chap_state *, u_char *, int, int);
  92 static void ChapRechallenge(void *);
  93 static void ChapReceiveResponse(chap_state *, u_char *, int, int);
  94 static void ChapReceiveSuccess(chap_state *, u_char *, int, int);
  95 static void ChapReceiveFailure(chap_state *, u_char *, int, int);
  96 static void ChapSendStatus(chap_state *, int);
  97 static void ChapSendChallenge(chap_state *);
  98 static void ChapSendResponse(chap_state *);
  99 static void ChapGenChallenge(chap_state *);
 100
 101 extern double drand48(void);
 102 extern void srand48(long);
 103
 104 /*
 105  * ChapInit - Initialize a CHAP unit.
 106  */
 107 static void
 108 ChapInit(unit)
 109     int unit;
 110 {
 111     chap_state *cstate = &chap[unit];
 112
 113     BZERO(cstate, sizeof(*cstate));
 114     cstate->unit = unit;
 115     cstate->clientstate = CHAPCS_INITIAL;
 116     cstate->serverstate = CHAPSS_INITIAL;
 117     cstate->timeouttime = CHAP_DEFTIMEOUT;
 118     cstate->max_transmits = CHAP_DEFTRANSMITS;
 119     /* random number generator is initialized in magic_init */
 120 }
 121
 122
 123 /*
 124  * ChapAuthWithPeer - Authenticate us with our peer (start client).
 125  *
 126  */
 127 void
 128 ChapAuthWithPeer(unit, our_name, digest)
 129     int unit;
 130     char *our_name;
 131     int digest;
 132 {
 133     chap_state *cstate = &chap[unit];
 134
 135     cstate->resp_name = our_name;
 136     cstate->resp_type = digest;
 137
 138     if (cstate->clientstate == CHAPCS_INITIAL ||
 139         cstate->clientstate == CHAPCS_PENDING) {
 140         /* lower layer isn't up - wait until later */
 141         cstate->clientstate = CHAPCS_PENDING;
 142         return;
 143     }
 144
 145     /*
 146      * We get here as a result of LCP coming up.
 147      * So even if CHAP was open before, we will
 148      * have to re-authenticate ourselves.
 149      */
 150     cstate->clientstate = CHAPCS_LISTEN;
 151 }
 152
 153
 154 /*
 155  * ChapAuthPeer - Authenticate our peer (start server).
 156  */
 157 void
 158 ChapAuthPeer(unit, our_name, digest)
 159     int unit;
 160     char *our_name;
 161     int digest;
 162 {
 163     chap_state *cstate = &chap[unit];
 164
 165     cstate->chal_name = our_name;
 166     cstate->chal_type = digest;
 167
 168     if (cstate->serverstate == CHAPSS_INITIAL ||
 169         cstate->serverstate == CHAPSS_PENDING) {
 170         /* lower layer isn't up - wait until later */
 171         cstate->serverstate = CHAPSS_PENDING;
 172         return;
 173     }
 174
 175     ChapGenChallenge(cstate);
 176     ChapSendChallenge(cstate);          /* crank it up dude! */
 177     cstate->serverstate = CHAPSS_INITIAL_CHAL;
 178 }
 179
 180
 181 /*
 182  * ChapChallengeTimeout - Timeout expired on sending challenge.
 183  */
 184 static void
 185 ChapChallengeTimeout(arg)
 186     void *arg;
 187 {
 188     chap_state *cstate = (chap_state *) arg;
 189
 190     /* if we aren't sending challenges, don't worry.  then again we */
 191     /* probably shouldn't be here either */
 192     if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
 193         cstate->serverstate != CHAPSS_RECHALLENGE)
 194         return;
 195
 196     if (cstate->chal_transmits >= cstate->max_transmits) {
 197         /* give up on peer */
 198         syslog(LOG_ERR, "Peer failed to respond to CHAP challenge");
 199         cstate->serverstate = CHAPSS_BADAUTH;
 200         auth_peer_fail(cstate->unit, PPP_CHAP);
 201         return;
 202     }
 203
 204     ChapSendChallenge(cstate);          /* Re-send challenge */
 205 }
 206
 207
 208 /*
 209  * ChapResponseTimeout - Timeout expired on sending response.
 210  */
 211 static void
 212 ChapResponseTimeout(arg)
 213     void *arg;
 214 {
 215     chap_state *cstate = (chap_state *) arg;
 216
 217     /* if we aren't sending a response, don't worry. */
 218     if (cstate->clientstate != CHAPCS_RESPONSE)
 219         return;
 220
 221     ChapSendResponse(cstate);           /* re-send response */
 222 }
 223
 224
 225 /*
 226  * ChapRechallenge - Time to challenge the peer again.
 227  */
 228 static void
 229 ChapRechallenge(arg)
 230     void *arg;
 231 {
 232     chap_state *cstate = (chap_state *) arg;
 233
 234     /* if we aren't sending a response, don't worry. */
 235     if (cstate->serverstate != CHAPSS_OPEN)
 236         return;
 237
 238     ChapGenChallenge(cstate);
 239     ChapSendChallenge(cstate);
 240     cstate->serverstate = CHAPSS_RECHALLENGE;
 241 }
 242
 243
 244 /*
 245  * ChapLowerUp - The lower layer is up.
 246  *
 247  * Start up if we have pending requests.
 248  */
 249 static void
 250 ChapLowerUp(unit)
 251     int unit;
 252 {
 253     chap_state *cstate = &chap[unit];
 254
 255     if (cstate->clientstate == CHAPCS_INITIAL)
 256         cstate->clientstate = CHAPCS_CLOSED;
 257     else if (cstate->clientstate == CHAPCS_PENDING)
 258         cstate->clientstate = CHAPCS_LISTEN;
 259
 260     if (cstate->serverstate == CHAPSS_INITIAL)
 261         cstate->serverstate = CHAPSS_CLOSED;
 262     else if (cstate->serverstate == CHAPSS_PENDING) {
 263         ChapGenChallenge(cstate);
 264         ChapSendChallenge(cstate);
 265         cstate->serverstate = CHAPSS_INITIAL_CHAL;
 266     }
 267 }
 268
 269
 270 /*
 271  * ChapLowerDown - The lower layer is down.
 272  *
 273  * Cancel all timeouts.
 274  */
 275 static void
 276 ChapLowerDown(unit)
 277     int unit;
 278 {
 279     chap_state *cstate = &chap[unit];
 280
 281     /* Timeout(s) pending?  Cancel if so. */
 282     if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
 283         cstate->serverstate == CHAPSS_RECHALLENGE)
 284         UNTIMEOUT(ChapChallengeTimeout, cstate);
 285     else if (cstate->serverstate == CHAPSS_OPEN
 286              && cstate->chal_interval != 0)
 287         UNTIMEOUT(ChapRechallenge, cstate);
 288     if (cstate->clientstate == CHAPCS_RESPONSE)
 289         UNTIMEOUT(ChapResponseTimeout, cstate);
 290
 291     cstate->clientstate = CHAPCS_INITIAL;
 292     cstate->serverstate = CHAPSS_INITIAL;
 293 }
 294
 295
 296 /*
 297  * ChapProtocolReject - Peer doesn't grok CHAP.
 298  */
 299 static void
 300 ChapProtocolReject(unit)
 301     int unit;
 302 {
 303     chap_state *cstate = &chap[unit];
 304
 305     if (cstate->serverstate != CHAPSS_INITIAL &&
 306         cstate->serverstate != CHAPSS_CLOSED)
 307         auth_peer_fail(unit, PPP_CHAP);
 308     if (cstate->clientstate != CHAPCS_INITIAL &&
 309         cstate->clientstate != CHAPCS_CLOSED)
 310         auth_withpeer_fail(unit, PPP_CHAP);
 311     ChapLowerDown(unit);                /* shutdown chap */
 312 }
 313
 314
 315 /*
 316  * ChapInput - Input CHAP packet.
 317  */
 318 static void
 319 ChapInput(unit, inpacket, packet_len)
 320     int unit;
 321     u_char *inpacket;
 322     int packet_len;
 323 {
 324     chap_state *cstate = &chap[unit];
 325     u_char *inp;
 326     u_char code, id;
 327     int len;
 328
 329     /*
 330      * Parse header (code, id and length).
 331      * If packet too short, drop it.
 332      */
 333     inp = inpacket;
 334     if (packet_len < CHAP_HEADERLEN) {
 335         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short header."));
 336         return;
 337     }
 338     GETCHAR(code, inp);
 339     GETCHAR(id, inp);
 340     GETSHORT(len, inp);
 341     if (len < CHAP_HEADERLEN) {
 342         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd illegal length."));
 343         return;
 344     }
 345     if (len > packet_len) {
 346         CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short packet."));
 347         return;
 348     }
 349     len -= CHAP_HEADERLEN;
 350
 351     /*
 352      * Action depends on code (as in fact it usually does :-).
 353      */
 354     switch (code) {
 355     case CHAP_CHALLENGE:
 356         ChapReceiveChallenge(cstate, inp, id, len);
 357         break;
 358
 359     case CHAP_RESPONSE:
 360         ChapReceiveResponse(cstate, inp, id, len);
 361         break;
 362
 363     case CHAP_FAILURE:
 364         ChapReceiveFailure(cstate, inp, id, len);
 365         break;
 366
 367     case CHAP_SUCCESS:
 368         ChapReceiveSuccess(cstate, inp, id, len);
 369         break;
 370
 371     default:                            /* Need code reject? */
 372         syslog(LOG_WARNING, "Unknown CHAP code (%d) received.", code);
 373         break;
 374     }
 375 }
 376
 377
 378 /*
 379  * ChapReceiveChallenge - Receive Challenge and send Response.
 380  */
 381 static void
 382 ChapReceiveChallenge(cstate, inp, id, len)
 383     chap_state *cstate;
 384     u_char *inp;
 385     int id;
 386     int len;
 387 {
 388     int rchallenge_len;
 389     u_char *rchallenge;
 390     int secret_len;
 391     char secret[MAXSECRETLEN];
 392     char rhostname[256];
 393     MD5_CTX mdContext;
 394     u_char hash[MD5_SIGNATURE_SIZE];
 395
 396     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: Rcvd id %d.", id));
 397     if (cstate->clientstate == CHAPCS_CLOSED ||
 398         cstate->clientstate == CHAPCS_PENDING) {
 399         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: in state %d",
 400                    cstate->clientstate));
 401         return;
 402     }
 403
 404     if (len < 2) {
 405         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 406         return;
 407     }
 408
 409     GETCHAR(rchallenge_len, inp);
 410     len -= sizeof (u_char) + rchallenge_len;    /* now name field length */
 411     if (len < 0) {
 412         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet."));
 413         return;
 414     }
 415     rchallenge = inp;
 416     INCPTR(rchallenge_len, inp);
 417
 418     if (len >= sizeof(rhostname))
 419         len = sizeof(rhostname) - 1;
 420     BCOPY(inp, rhostname, len);
 421     rhostname[len] = '\000';
 422
 423     CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: received name field '%s'",
 424                rhostname));
 425
 426     /* Microsoft doesn't send their name back in the PPP packet */
 427     if (remote_name[0] != 0 && (explicit_remote || rhostname[0] == 0)) {
 428         strncpy(rhostname, remote_name, sizeof(rhostname));
 429         rhostname[sizeof(rhostname) - 1] = 0;
 430         CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: using '%s' as remote name",
 431                    rhostname));
 432     }
 433
 434     /* get secret for authenticating ourselves with the specified host */
 435     if (!get_secret(cstate->unit, cstate->resp_name, rhostname,
 436                     secret, &secret_len, 0)) {
 437         secret_len = 0;         /* assume null secret if can't find one */
 438         syslog(LOG_WARNING, "No CHAP secret found for authenticating us to %s",
 439                rhostname);
 440     }
 441
 442     /* cancel response send timeout if necessary */
 443     if (cstate->clientstate == CHAPCS_RESPONSE)
 444         UNTIMEOUT(ChapResponseTimeout, cstate);
 445
 446     cstate->resp_id = id;
 447     cstate->resp_transmits = 0;
 448
 449     /*  generate MD based on negotiated type */
 450     switch (cstate->resp_type) {
 451
 452     case CHAP_DIGEST_MD5:
 453         MD5Init(&mdContext);
 454         MD5Update(&mdContext, &cstate->resp_id, 1);
 455         MD5Update(&mdContext, secret, secret_len);
 456         MD5Update(&mdContext, rchallenge, rchallenge_len);
 457         MD5Final(hash, &mdContext);
 458         BCOPY(hash, cstate->response, MD5_SIGNATURE_SIZE);
 459         cstate->resp_length = MD5_SIGNATURE_SIZE;
 460         break;
 461
 462 #ifdef CHAPMS
 463     case CHAP_MICROSOFT:
 464         ChapMS(cstate, rchallenge, rchallenge_len, secret, secret_len);
 465         break;
 466 #endif
 467
 468     default:
 469         CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->resp_type));
 470         return;
 471     }
 472
 473     BZERO(secret, sizeof(secret));
 474     ChapSendResponse(cstate);
 475 }
 476
 477
 478 /*
 479  * ChapReceiveResponse - Receive and process response.
 480  */
 481 static void
 482 ChapReceiveResponse(cstate, inp, id, len)
 483     chap_state *cstate;
 484     u_char *inp;
 485     int id;
 486     int len;
 487 {
 488     u_char *remmd, remmd_len;
 489     int secret_len, old_state;
 490     int code;
 491     char rhostname[256];
 492     MD5_CTX mdContext;
 493     char secret[MAXSECRETLEN];
 494     u_char hash[MD5_SIGNATURE_SIZE];
 495
 496     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: Rcvd id %d.", id));
 497
 498     if (cstate->serverstate == CHAPSS_CLOSED ||
 499         cstate->serverstate == CHAPSS_PENDING) {
 500         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: in state %d",
 501                    cstate->serverstate));
 502         return;
 503     }
 504
 505     if (id != cstate->chal_id)
 506         return;                 /* doesn't match ID of last challenge */
 507
 508     /*
 509      * If we have received a duplicate or bogus Response,
 510      * we have to send the same answer (Success/Failure)
 511      * as we did for the first Response we saw.
 512      */
 513     if (cstate->serverstate == CHAPSS_OPEN) {
 514         ChapSendStatus(cstate, CHAP_SUCCESS);
 515         return;
 516     }
 517     if (cstate->serverstate == CHAPSS_BADAUTH) {
 518         ChapSendStatus(cstate, CHAP_FAILURE);
 519         return;
 520     }
 521
 522     if (len < 2) {
 523         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 524         return;
 525     }
 526     GETCHAR(remmd_len, inp);            /* get length of MD */
 527     remmd = inp;                        /* get pointer to MD */
 528     INCPTR(remmd_len, inp);
 529
 530     len -= sizeof (u_char) + remmd_len;
 531     if (len < 0) {
 532         CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: rcvd short packet."));
 533         return;
 534     }
 535
 536     UNTIMEOUT(ChapChallengeTimeout, cstate);
 537
 538     if (len >= sizeof(rhostname))
 539         len = sizeof(rhostname) - 1;
 540     BCOPY(inp, rhostname, len);
 541     rhostname[len] = '\000';
 542
 543     CHAPDEBUG((LOG_INFO, "ChapReceiveResponse: received name field: %s",
 544                rhostname));
 545
 546     /*
 547      * Get secret for authenticating them with us,
 548      * do the hash ourselves, and compare the result.
 549      */
 550     code = CHAP_FAILURE;
 551     if (!get_secret(cstate->unit, rhostname, cstate->chal_name,
 552                    secret, &secret_len, 1)) {
 553         syslog(LOG_WARNING, "No CHAP secret found for authenticating %s",
 554                rhostname);
 555     } else {
 556
 557         /*  generate MD based on negotiated type */
 558         switch (cstate->chal_type) {
 559
 560         case CHAP_DIGEST_MD5:           /* only MD5 is defined for now */
 561             if (remmd_len != MD5_SIGNATURE_SIZE)
 562                 break;                  /* it's not even the right length */
 563             MD5Init(&mdContext);
 564             MD5Update(&mdContext, &cstate->chal_id, 1);
 565             MD5Update(&mdContext, secret, secret_len);
 566             MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
 567             MD5Final(hash, &mdContext);
 568
 569             /* compare local and remote MDs and send the appropriate status */
 570             if (memcmp (hash, remmd, MD5_SIGNATURE_SIZE) == 0)
 571                 code = CHAP_SUCCESS;    /* they are the same! */
 572             break;
 573
 574         default:
 575             CHAPDEBUG((LOG_INFO, "unknown digest type %d", cstate->chal_type));
 576         }
 577     }
 578
 579     BZERO(secret, sizeof(secret));
 580     ChapSendStatus(cstate, code);
 581
 582     if (code == CHAP_SUCCESS) {
 583         old_state = cstate->serverstate;
 584         cstate->serverstate = CHAPSS_OPEN;
 585         if (old_state == CHAPSS_INITIAL_CHAL) {
 586             auth_peer_success(cstate->unit, PPP_CHAP, rhostname, len);
 587         }
 588         if (cstate->chal_interval != 0)
 589             TIMEOUT(ChapRechallenge, cstate, cstate->chal_interval);
 590         syslog(LOG_NOTICE, "CHAP peer authentication succeeded for %s",
 591                rhostname);
 592
 593     } else {
 594         syslog(LOG_ERR, "CHAP peer authentication failed for remote host %s",
 595                rhostname);
 596         cstate->serverstate = CHAPSS_BADAUTH;
 597         auth_peer_fail(cstate->unit, PPP_CHAP);
 598     }
 599 }
 600
 601 /*
 602  * ChapReceiveSuccess - Receive Success
 603  */
 604 static void
 605 ChapReceiveSuccess(cstate, inp, id, len)
 606     chap_state *cstate;
 607     u_char *inp;
 608     u_char id;
 609     int len;
 610 {
 611
 612     CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: Rcvd id %d.", id));
 613
 614     if (cstate->clientstate == CHAPCS_OPEN)
 615         /* presumably an answer to a duplicate response */
 616         return;
 617
 618     if (cstate->clientstate != CHAPCS_RESPONSE) {
 619         /* don't know what this is */
 620         CHAPDEBUG((LOG_INFO, "ChapReceiveSuccess: in state %d\n",
 621                    cstate->clientstate));
 622         return;
 623     }
 624
 625     UNTIMEOUT(ChapResponseTimeout, cstate);
 626
 627     /*
 628      * Print message.
 629      */
 630     if (len > 0)
 631         PRINTMSG(inp, len);
 632
 633     cstate->clientstate = CHAPCS_OPEN;
 634
 635     auth_withpeer_success(cstate->unit, PPP_CHAP);
 636 }
 637
 638
 639 /*
 640  * ChapReceiveFailure - Receive failure.
 641  */
 642 static void
 643 ChapReceiveFailure(cstate, inp, id, len)
 644     chap_state *cstate;
 645     u_char *inp;
 646     u_char id;
 647     int len;
 648 {
 649     CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: Rcvd id %d.", id));
 650
 651     if (cstate->clientstate != CHAPCS_RESPONSE) {
 652         /* don't know what this is */
 653         CHAPDEBUG((LOG_INFO, "ChapReceiveFailure: in state %d\n",
 654                    cstate->clientstate));
 655         return;
 656     }
 657
 658     UNTIMEOUT(ChapResponseTimeout, cstate);
 659
 660     /*
 661      * Print message.
 662      */
 663     if (len > 0)
 664         PRINTMSG(inp, len);
 665
 666     syslog(LOG_ERR, "CHAP authentication failed");
 667     auth_withpeer_fail(cstate->unit, PPP_CHAP);
 668 }
 669
 670
 671 /*
 672  * ChapSendChallenge - Send an Authenticate challenge.
 673  */
 674 static void
 675 ChapSendChallenge(cstate)
 676     chap_state *cstate;
 677 {
 678     u_char *outp;
 679     int chal_len, name_len;
 680     int outlen;
 681
 682     chal_len = cstate->chal_len;
 683     name_len = strlen(cstate->chal_name);
 684     outlen = CHAP_HEADERLEN + sizeof (u_char) + chal_len + name_len;
 685     outp = outpacket_buf;
 686
 687     MAKEHEADER(outp, PPP_CHAP);         /* paste in a CHAP header */
 688
 689     PUTCHAR(CHAP_CHALLENGE, outp);
 690     PUTCHAR(cstate->chal_id, outp);
 691     PUTSHORT(outlen, outp);
 692
 693     PUTCHAR(chal_len, outp);            /* put length of challenge */
 694     BCOPY(cstate->challenge, outp, chal_len);
 695     INCPTR(chal_len, outp);
 696
 697     BCOPY(cstate->chal_name, outp, name_len);   /* append hostname */
 698
 699     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 700
 701     CHAPDEBUG((LOG_INFO, "ChapSendChallenge: Sent id %d.", cstate->chal_id));
 702
 703     TIMEOUT(ChapChallengeTimeout, cstate, cstate->timeouttime);
 704     ++cstate->chal_transmits;
 705 }
 706
 707
 708 /*
 709  * ChapSendStatus - Send a status response (ack or nak).
 710  */
 711 static void
 712 ChapSendStatus(cstate, code)
 713     chap_state *cstate;
 714     int code;
 715 {
 716     u_char *outp;
 717     int outlen, msglen;
 718     char msg[256];
 719
 720     if (code == CHAP_SUCCESS)
 721         sprintf(msg, "Welcome to %s.", hostname);
 722     else
 723         sprintf(msg, "I don't like you.  Go 'way.");
 724     msglen = strlen(msg);
 725
 726     outlen = CHAP_HEADERLEN + msglen;
 727     outp = outpacket_buf;
 728
 729     MAKEHEADER(outp, PPP_CHAP); /* paste in a header */
 730
 731     PUTCHAR(code, outp);
 732     PUTCHAR(cstate->chal_id, outp);
 733     PUTSHORT(outlen, outp);
 734     BCOPY(msg, outp, msglen);
 735     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 736
 737     CHAPDEBUG((LOG_INFO, "ChapSendStatus: Sent code %d, id %d.", code,
 738                cstate->chal_id));
 739 }
 740
 741 /*
 742  * ChapGenChallenge is used to generate a pseudo-random challenge string of
 743  * a pseudo-random length between min_len and max_len.  The challenge
 744  * string and its length are stored in *cstate, and various other fields of
 745  * *cstate are initialized.
 746  */
 747
 748 static void
 749 ChapGenChallenge(cstate)
 750     chap_state *cstate;
 751 {
 752     int chal_len;
 753     u_char *ptr = cstate->challenge;
 754     unsigned int i;
 755
 756     /* pick a random challenge length between MIN_CHALLENGE_LENGTH and
 757        MAX_CHALLENGE_LENGTH */
 758     chal_len =  (unsigned) ((drand48() *
 759                              (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
 760                             MIN_CHALLENGE_LENGTH);
 761     cstate->chal_len = chal_len;
 762     cstate->chal_id = ++cstate->id;
 763     cstate->chal_transmits = 0;
 764
 765     /* generate a random string */
 766     for (i = 0; i < chal_len; i++ )
 767         *ptr++ = (char) (drand48() * 0xff);
 768 }
 769
 770 /*
 771  * ChapSendResponse - send a response packet with values as specified
 772  * in *cstate.
 773  */
 774 /* ARGSUSED */
 775 static void
 776 ChapSendResponse(cstate)
 777     chap_state *cstate;
 778 {
 779     u_char *outp;
 780     int outlen, md_len, name_len;
 781
 782     md_len = cstate->resp_length;
 783     name_len = strlen(cstate->resp_name);
 784     outlen = CHAP_HEADERLEN + sizeof (u_char) + md_len + name_len;
 785     outp = outpacket_buf;
 786
 787     MAKEHEADER(outp, PPP_CHAP);
 788
 789     PUTCHAR(CHAP_RESPONSE, outp);       /* we are a response */
 790     PUTCHAR(cstate->resp_id, outp);     /* copy id from challenge packet */
 791     PUTSHORT(outlen, outp);             /* packet length */
 792
 793     PUTCHAR(md_len, outp);              /* length of MD */
 794     BCOPY(cstate->response, outp, md_len);      /* copy MD to buffer */
 795     INCPTR(md_len, outp);
 796
 797     BCOPY(cstate->resp_name, outp, name_len); /* append our name */
 798
 799     /* send the packet */
 800     output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
 801
 802     cstate->clientstate = CHAPCS_RESPONSE;
 803     TIMEOUT(ChapResponseTimeout, cstate, cstate->timeouttime);
 804     ++cstate->resp_transmits;
 805 }
 806
 807 /*
 808  * ChapPrintPkt - print the contents of a CHAP packet.
 809  */
 810 static char *ChapCodenames[] = {
 811     "Challenge", "Response", "Success", "Failure"
 812 };
 813
 814 static int
 815 ChapPrintPkt(p, plen, printer, arg)
 816     u_char *p;
 817     int plen;
 818     void (*printer)(void *, char *, ...);
 819     void *arg;
 820 {
 821     int code, id, len;
 822     int clen, nlen;
 823     u_char x;
 824
 825     if (plen < CHAP_HEADERLEN)
 826         return 0;
 827     GETCHAR(code, p);
 828     GETCHAR(id, p);
 829     GETSHORT(len, p);
 830     if (len < CHAP_HEADERLEN || len > plen)
 831         return 0;
 832
 833     if (code >= 1 && code <= sizeof(ChapCodenames) / sizeof(char *))
 834         printer(arg, " %s", ChapCodenames[code-1]);
 835     else
 836         printer(arg, " code=0x%x", code);
 837     printer(arg, " id=0x%x", id);
 838     len -= CHAP_HEADERLEN;
 839     switch (code) {
 840     case CHAP_CHALLENGE:
 841     case CHAP_RESPONSE:
 842         if (len < 1)
 843             break;
 844         clen = p[0];
 845         if (len < clen + 1)
 846             break;
 847         ++p;
 848         nlen = len - clen - 1;
 849         printer(arg, " <");
 850         for (; clen > 0; --clen) {
 851             GETCHAR(x, p);
 852             printer(arg, "%.2x", x);
 853         }
 854         printer(arg, ">, name = ");
 855         print_string((char *)p, nlen, printer, arg);
 856         break;
 857     case CHAP_FAILURE:
 858     case CHAP_SUCCESS:
 859         printer(arg, " ");
 860         print_string((char *)p, len, printer, arg);
 861         break;
 862     default:
 863         for (clen = len; clen > 0; --clen) {
 864             GETCHAR(x, p);
 865             printer(arg, " %.2x", x);
 866         }
 867     }
 868
 869     return len + CHAP_HEADERLEN;
 870 }