2 * chap_ms.c - Challenge Handshake Authentication Protocol.
4 * Copyright (c) 1993 The Australian National University.
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.
19 * Copyright (c) 1991 Gregory M. Christy.
20 * All rights reserved.
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.
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.
36 #define RCSID "$Id: chap.c,v 1.33 2002/09/01 12:00:15 dfs Exp $"
45 #include <sys/types.h>
55 /* Hook for a plugin to say if we can possibly authenticate a peer using CHAP */
56 int (*chap_check_hook) __P((void)) = NULL;
58 /* Hook for a plugin to get the CHAP password for authenticating us */
59 int (*chap_passwd_hook) __P((char *user, char *passwd)) = NULL;
61 /* Hook for a plugin to validate CHAP challenge */
62 int (*chap_auth_hook) __P((char *user,
65 chap_state *cstate)) = NULL;
67 static const char rcsid[] = RCSID;
71 /* Use "[]|}{?/><,`!2&&(" (sans quotes) for RFC 3079 MS-CHAPv2 test value */
72 static char *mschap_challenge = NULL;
73 /* Use "!@\#$%^&*()_+:3|~" (sans quotes, backslash is to escape #) for ... */
74 static char *mschap2_peer_challenge = NULL;
78 * Command-line options.
80 static option_t chap_option_list[] = {
81 { "chap-restart", o_int, &chap[0].timeouttime,
82 "Set timeout for CHAP", OPT_PRIO },
83 { "chap-max-challenge", o_int, &chap[0].max_transmits,
84 "Set max #xmits for challenge", OPT_PRIO },
85 { "chap-interval", o_int, &chap[0].chal_interval,
86 "Set interval for rechallenge", OPT_PRIO },
88 { "ms-lanman", o_bool, &ms_lanman,
89 "Use LanMan passwd when using MS-CHAP", 1 },
92 { "mschap-challenge", o_string, &mschap_challenge,
93 "specify CHAP challenge" },
94 { "mschap2-peer-challenge", o_string, &mschap2_peer_challenge,
95 "specify CHAP peer challenge" },
101 * Protocol entry points.
103 static void ChapInit __P((int));
104 static void ChapLowerUp __P((int));
105 static void ChapLowerDown __P((int));
106 static void ChapInput __P((int, u_char *, int));
107 static void ChapProtocolReject __P((int));
108 static int ChapPrintPkt __P((u_char *, int,
109 void (*) __P((void *, char *, ...)), void *));
111 struct protent chap_protent = {
131 chap_state chap[NUM_PPP]; /* CHAP state; one for each unit */
133 static void ChapChallengeTimeout __P((void *));
134 static void ChapResponseTimeout __P((void *));
135 static void ChapReceiveChallenge __P((chap_state *, u_char *, int, int));
136 static void ChapRechallenge __P((void *));
137 static void ChapReceiveResponse __P((chap_state *, u_char *, int, int));
138 static void ChapReceiveSuccess __P((chap_state *, u_char *, int, int));
139 static void ChapReceiveFailure __P((chap_state *, u_char *, int, int));
140 static void ChapSendStatus __P((chap_state *, int));
141 static void ChapSendChallenge __P((chap_state *));
142 static void ChapSendResponse __P((chap_state *));
143 static void ChapGenChallenge __P((chap_state *));
145 extern double drand48 __P((void));
146 extern void srand48 __P((long));
149 * ChapInit - Initialize a CHAP unit.
155 chap_state *cstate = &chap[unit];
157 BZERO(cstate, sizeof(*cstate));
159 cstate->clientstate = CHAPCS_INITIAL;
160 cstate->serverstate = CHAPSS_INITIAL;
161 cstate->timeouttime = CHAP_DEFTIMEOUT;
162 cstate->max_transmits = CHAP_DEFTRANSMITS;
163 /* random number generator is initialized in magic_init */
168 * ChapAuthWithPeer - Authenticate us with our peer (start client).
172 ChapAuthWithPeer(unit, our_name, digest)
177 chap_state *cstate = &chap[unit];
179 cstate->resp_name = our_name;
180 cstate->resp_type = digest;
182 if (cstate->clientstate == CHAPCS_INITIAL ||
183 cstate->clientstate == CHAPCS_PENDING) {
184 /* lower layer isn't up - wait until later */
185 cstate->clientstate = CHAPCS_PENDING;
190 * We get here as a result of LCP coming up.
191 * So even if CHAP was open before, we will
192 * have to re-authenticate ourselves.
194 cstate->clientstate = CHAPCS_LISTEN;
199 * ChapAuthPeer - Authenticate our peer (start server).
202 ChapAuthPeer(unit, our_name, digest)
207 chap_state *cstate = &chap[unit];
209 cstate->chal_name = our_name;
210 cstate->chal_type = digest;
212 if (cstate->serverstate == CHAPSS_INITIAL ||
213 cstate->serverstate == CHAPSS_PENDING) {
214 /* lower layer isn't up - wait until later */
215 cstate->serverstate = CHAPSS_PENDING;
219 ChapGenChallenge(cstate);
220 ChapSendChallenge(cstate); /* crank it up dude! */
221 cstate->serverstate = CHAPSS_INITIAL_CHAL;
226 * ChapChallengeTimeout - Timeout expired on sending challenge.
229 ChapChallengeTimeout(arg)
232 chap_state *cstate = (chap_state *) arg;
234 /* if we aren't sending challenges, don't worry. then again we */
235 /* probably shouldn't be here either */
236 if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
237 cstate->serverstate != CHAPSS_RECHALLENGE)
240 if (cstate->chal_transmits >= cstate->max_transmits) {
241 /* give up on peer */
242 error("Peer failed to respond to CHAP challenge");
243 cstate->serverstate = CHAPSS_BADAUTH;
244 auth_peer_fail(cstate->unit, PPP_CHAP);
248 ChapSendChallenge(cstate); /* Re-send challenge */
253 * ChapResponseTimeout - Timeout expired on sending response.
256 ChapResponseTimeout(arg)
259 chap_state *cstate = (chap_state *) arg;
261 /* if we aren't sending a response, don't worry. */
262 if (cstate->clientstate != CHAPCS_RESPONSE)
265 ChapSendResponse(cstate); /* re-send response */
270 * ChapRechallenge - Time to challenge the peer again.
276 chap_state *cstate = (chap_state *) arg;
278 /* if we aren't sending a response, don't worry. */
279 if (cstate->serverstate != CHAPSS_OPEN)
282 ChapGenChallenge(cstate);
283 ChapSendChallenge(cstate);
284 cstate->serverstate = CHAPSS_RECHALLENGE;
289 * ChapLowerUp - The lower layer is up.
291 * Start up if we have pending requests.
297 chap_state *cstate = &chap[unit];
299 if (cstate->clientstate == CHAPCS_INITIAL)
300 cstate->clientstate = CHAPCS_CLOSED;
301 else if (cstate->clientstate == CHAPCS_PENDING)
302 cstate->clientstate = CHAPCS_LISTEN;
304 if (cstate->serverstate == CHAPSS_INITIAL)
305 cstate->serverstate = CHAPSS_CLOSED;
306 else if (cstate->serverstate == CHAPSS_PENDING) {
307 ChapGenChallenge(cstate);
308 ChapSendChallenge(cstate);
309 cstate->serverstate = CHAPSS_INITIAL_CHAL;
315 * ChapLowerDown - The lower layer is down.
317 * Cancel all timeouts.
323 chap_state *cstate = &chap[unit];
325 /* Timeout(s) pending? Cancel if so. */
326 if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
327 cstate->serverstate == CHAPSS_RECHALLENGE)
328 UNTIMEOUT(ChapChallengeTimeout, cstate);
329 else if (cstate->serverstate == CHAPSS_OPEN
330 && cstate->chal_interval != 0)
331 UNTIMEOUT(ChapRechallenge, cstate);
332 if (cstate->clientstate == CHAPCS_RESPONSE)
333 UNTIMEOUT(ChapResponseTimeout, cstate);
335 cstate->clientstate = CHAPCS_INITIAL;
336 cstate->serverstate = CHAPSS_INITIAL;
341 * ChapProtocolReject - Peer doesn't grok CHAP.
344 ChapProtocolReject(unit)
347 chap_state *cstate = &chap[unit];
349 if (cstate->serverstate != CHAPSS_INITIAL &&
350 cstate->serverstate != CHAPSS_CLOSED)
351 auth_peer_fail(unit, PPP_CHAP);
352 if (cstate->clientstate != CHAPCS_INITIAL &&
353 cstate->clientstate != CHAPCS_CLOSED)
354 auth_withpeer_fail(unit, PPP_CHAP);
355 ChapLowerDown(unit); /* shutdown chap */
360 * ChapInput - Input CHAP packet.
363 ChapInput(unit, inpacket, packet_len)
368 chap_state *cstate = &chap[unit];
374 * Parse header (code, id and length).
375 * If packet too short, drop it.
378 if (packet_len < CHAP_HEADERLEN) {
379 CHAPDEBUG(("ChapInput: rcvd short header."));
385 if (len < CHAP_HEADERLEN) {
386 CHAPDEBUG(("ChapInput: rcvd illegal length."));
389 if (len > packet_len) {
390 CHAPDEBUG(("ChapInput: rcvd short packet."));
393 len -= CHAP_HEADERLEN;
396 * Action depends on code (as in fact it usually does :-).
400 ChapReceiveChallenge(cstate, inp, id, len);
404 ChapReceiveResponse(cstate, inp, id, len);
408 ChapReceiveFailure(cstate, inp, id, len);
412 ChapReceiveSuccess(cstate, inp, id, len);
415 default: /* Need code reject? */
416 warn("Unknown CHAP code (%d) received.", code);
423 * ChapReceiveChallenge - Receive Challenge and send Response.
426 ChapReceiveChallenge(cstate, inp, id, len)
435 char secret[MAXSECRETLEN];
438 u_char hash[MD5_SIGNATURE_SIZE];
440 if (cstate->clientstate == CHAPCS_CLOSED ||
441 cstate->clientstate == CHAPCS_PENDING) {
442 CHAPDEBUG(("ChapReceiveChallenge: in state %d", cstate->clientstate));
447 CHAPDEBUG(("ChapReceiveChallenge: rcvd short packet."));
451 GETCHAR(rchallenge_len, inp);
452 len -= sizeof (u_char) + rchallenge_len; /* now name field length */
454 CHAPDEBUG(("ChapReceiveChallenge: rcvd short packet."));
458 INCPTR(rchallenge_len, inp);
460 if (len >= sizeof(rhostname))
461 len = sizeof(rhostname) - 1;
462 BCOPY(inp, rhostname, len);
463 rhostname[len] = '\000';
465 /* Microsoft doesn't send their name back in the PPP packet */
466 if (explicit_remote || (remote_name[0] != 0 && rhostname[0] == 0)) {
467 strlcpy(rhostname, remote_name, sizeof(rhostname));
468 CHAPDEBUG(("ChapReceiveChallenge: using '%q' as remote name",
472 /* get secret for authenticating ourselves with the specified host */
473 if (!get_secret(cstate->unit, cstate->resp_name, rhostname,
474 secret, &secret_len, 0)) {
475 secret_len = 0; /* assume null secret if can't find one */
476 warn("No CHAP secret found for authenticating us to %q", rhostname);
479 /* cancel response send timeout if necessary */
480 if (cstate->clientstate == CHAPCS_RESPONSE)
481 UNTIMEOUT(ChapResponseTimeout, cstate);
483 cstate->resp_id = id;
484 cstate->resp_transmits = 0;
486 /* generate MD based on negotiated type */
487 switch (cstate->resp_type) {
489 case CHAP_DIGEST_MD5:
491 MD5Update(&mdContext, &cstate->resp_id, 1);
492 MD5Update(&mdContext, secret, secret_len);
493 MD5Update(&mdContext, rchallenge, rchallenge_len);
494 MD5Final(hash, &mdContext);
495 BCOPY(hash, cstate->response, MD5_SIGNATURE_SIZE);
496 cstate->resp_length = MD5_SIGNATURE_SIZE;
501 ChapMS(cstate, rchallenge, secret, secret_len,
502 (MS_ChapResponse *) cstate->response);
505 case CHAP_MICROSOFT_V2:
506 ChapMS2(cstate, rchallenge,
507 mschap2_peer_challenge? mschap2_peer_challenge: NULL,
508 cstate->resp_name, secret, secret_len,
509 (MS_Chap2Response *) cstate->response, cstate->earesponse,
510 MS_CHAP2_AUTHENTICATEE);
515 CHAPDEBUG(("unknown digest type %d", cstate->resp_type));
519 BZERO(secret, sizeof(secret));
520 ChapSendResponse(cstate);
525 * ChapReceiveResponse - Receive and process response.
528 ChapReceiveResponse(cstate, inp, id, len)
534 u_char *remmd, remmd_len;
535 int secret_len, old_state;
539 char secret[MAXSECRETLEN];
540 u_char hash[MD5_SIGNATURE_SIZE];
542 if (cstate->serverstate == CHAPSS_CLOSED ||
543 cstate->serverstate == CHAPSS_PENDING) {
544 CHAPDEBUG(("ChapReceiveResponse: in state %d", cstate->serverstate));
548 if (id != cstate->chal_id)
549 return; /* doesn't match ID of last challenge */
552 * If we have received a duplicate or bogus Response,
553 * we have to send the same answer (Success/Failure)
554 * as we did for the first Response we saw.
556 if (cstate->serverstate == CHAPSS_OPEN) {
557 ChapSendStatus(cstate, CHAP_SUCCESS);
560 if (cstate->serverstate == CHAPSS_BADAUTH) {
561 ChapSendStatus(cstate, CHAP_FAILURE);
566 CHAPDEBUG(("ChapReceiveResponse: rcvd short packet."));
569 GETCHAR(remmd_len, inp); /* get length of MD */
570 remmd = inp; /* get pointer to MD */
571 INCPTR(remmd_len, inp);
573 len -= sizeof (u_char) + remmd_len;
575 CHAPDEBUG(("ChapReceiveResponse: rcvd short packet."));
579 UNTIMEOUT(ChapChallengeTimeout, cstate);
581 if (len >= sizeof(rhostname))
582 len = sizeof(rhostname) - 1;
583 BCOPY(inp, rhostname, len);
584 rhostname[len] = '\000';
587 /* copy the flags into cstate for use elsewhere */
588 if (cstate->chal_type == CHAP_MICROSOFT_V2)
589 cstate->resp_flags = ((MS_Chap2Response *) remmd)->Flags[0];
592 * Get secret for authenticating them with us,
593 * do the hash ourselves, and compare the result.
597 /* If a plugin will verify the response, let the plugin do it. */
598 if (chap_auth_hook) {
599 code = (*chap_auth_hook) ( (explicit_remote ? remote_name : rhostname),
600 remmd, (int) remmd_len,
603 if (!get_secret(cstate->unit, (explicit_remote? remote_name: rhostname),
604 cstate->chal_name, secret, &secret_len, 1)) {
605 warn("No CHAP secret found for authenticating %q", rhostname);
608 /* generate MD based on negotiated type */
609 switch (cstate->chal_type) {
611 case CHAP_DIGEST_MD5:
612 if (remmd_len != MD5_SIGNATURE_SIZE)
613 break; /* not even the right length */
615 MD5Update(&mdContext, &cstate->chal_id, 1);
616 MD5Update(&mdContext, secret, secret_len);
617 MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
618 MD5Final(hash, &mdContext);
620 /* compare MDs and send the appropriate status */
621 if (memcmp(hash, remmd, MD5_SIGNATURE_SIZE) == 0)
622 code = CHAP_SUCCESS; /* they are the same! */
628 int response_offset, response_size;
629 MS_ChapResponse *rmd = (MS_ChapResponse *) remmd;
632 if (remmd_len != MS_CHAP_RESPONSE_LEN)
633 break; /* not even the right length */
635 /* Determine which part of response to verify against */
637 response_offset = offsetof(MS_ChapResponse, NTResp);
638 response_size = sizeof(rmd->NTResp);
641 response_offset = offsetof(MS_ChapResponse, LANManResp);
642 response_size = sizeof(rmd->LANManResp);
644 /* Should really propagate this into the error packet. */
645 notice("Peer request for LANMAN auth not supported");
647 #endif /* MSLANMAN */
650 /* Generate the expected response. */
651 ChapMS(cstate, cstate->challenge, secret, secret_len, &md);
653 /* compare MDs and send the appropriate status */
654 if (memcmp((u_char *) &md + response_offset,
655 (u_char *) remmd + response_offset,
657 code = CHAP_SUCCESS; /* they are the same! */
661 case CHAP_MICROSOFT_V2:
663 MS_Chap2Response *rmd = (MS_Chap2Response *) remmd;
666 if (remmd_len != MS_CHAP2_RESPONSE_LEN)
667 break; /* not even the right length */
669 /* Generate the expected response and our mutual auth. */
670 ChapMS2(cstate, cstate->challenge, rmd->PeerChallenge,
671 (explicit_remote? remote_name: rhostname),
672 secret, secret_len, &md,
673 cstate->saresponse, MS_CHAP2_AUTHENTICATOR);
675 /* compare MDs and send the appropriate status */
676 if (memcmp(md.NTResp, rmd->NTResp, sizeof(md.NTResp)) == 0)
677 code = CHAP_SUCCESS; /* yay! */
683 CHAPDEBUG(("unknown digest type %d", cstate->chal_type));
687 BZERO(secret, sizeof(secret));
689 ChapSendStatus(cstate, code);
691 if (code == CHAP_SUCCESS) {
692 old_state = cstate->serverstate;
693 cstate->serverstate = CHAPSS_OPEN;
694 if (old_state == CHAPSS_INITIAL_CHAL) {
695 auth_peer_success(cstate->unit, PPP_CHAP, cstate->chal_type,
698 if (cstate->chal_interval != 0)
699 TIMEOUT(ChapRechallenge, cstate, cstate->chal_interval);
700 notice("CHAP peer authentication succeeded for %q", rhostname);
703 error("CHAP peer authentication failed for remote host %q", rhostname);
704 cstate->serverstate = CHAPSS_BADAUTH;
705 auth_peer_fail(cstate->unit, PPP_CHAP);
710 * ChapReceiveSuccess - Receive Success
713 ChapReceiveSuccess(cstate, inp, id, len)
720 if (cstate->clientstate == CHAPCS_OPEN)
721 /* presumably an answer to a duplicate response */
724 if (cstate->clientstate != CHAPCS_RESPONSE) {
725 /* don't know what this is */
726 CHAPDEBUG(("ChapReceiveSuccess: in state %d\n", cstate->clientstate));
730 UNTIMEOUT(ChapResponseTimeout, cstate);
734 * For MS-CHAPv2, we must verify that the peer knows our secret.
736 if (cstate->resp_type == CHAP_MICROSOFT_V2) {
737 if ((len >= MS_AUTH_RESPONSE_LENGTH + 2) && !strncmp(inp, "S=", 2)) {
739 if (!memcmp(inp, cstate->earesponse, MS_AUTH_RESPONSE_LENGTH)) {
740 /* Authenticator Response matches. */
741 inp += MS_AUTH_RESPONSE_LENGTH; /* Eat it */
742 len -= MS_AUTH_RESPONSE_LENGTH;
743 if ((len >= 3) && !strncmp(inp, " M=", 3)) {
744 inp += 3; len -= 3; /* Eat the delimiter */
746 /* Packet has extra text which does not begin " M=" */
747 error("MS-CHAPv2 Success packet is badly formed.");
748 auth_withpeer_fail(cstate->unit, PPP_CHAP);
751 /* Authenticator Response did not match expected. */
752 error("MS-CHAPv2 mutual authentication failed.");
753 auth_withpeer_fail(cstate->unit, PPP_CHAP);
756 /* Packet does not start with "S=" */
757 error("MS-CHAPv2 Success packet is badly formed.");
758 auth_withpeer_fail(cstate->unit, PPP_CHAP);
769 cstate->clientstate = CHAPCS_OPEN;
771 auth_withpeer_success(cstate->unit, PPP_CHAP, cstate->resp_type);
776 * ChapReceiveFailure - Receive failure.
779 ChapReceiveFailure(cstate, inp, id, len)
788 if (cstate->clientstate != CHAPCS_RESPONSE) {
789 /* don't know what this is */
790 CHAPDEBUG(("ChapReceiveFailure: in state %d\n", cstate->clientstate));
795 /* We want a null-terminated string for strxxx(). */
796 msg = malloc(len + 1);
799 notice("Out of memory in ChapReceiveFailure");
802 BCOPY(inp, msg, len);
803 p = msg + len; *p = '\0'; p = msg;
806 UNTIMEOUT(ChapResponseTimeout, cstate);
809 if ((cstate->resp_type == CHAP_MICROSOFT_V2) ||
810 (cstate->resp_type == CHAP_MICROSOFT)) {
814 * Deal with MS-CHAP formatted failure messages; just print the
815 * M=<message> part (if any). For MS-CHAP we're not really supposed
816 * to use M=<message>, but it shouldn't hurt. See ChapSendStatus().
818 if (!strncmp(p, "E=", 2))
819 error = (int) strtol(p, NULL, 10); /* Remember the error code. */
821 goto print_msg; /* Message is badly formatted. */
823 if (len && ((p = strstr(p, " M=")) != NULL)) {
824 /* M=<message> field found. */
827 /* No M=<message>; use the error code. */
829 case MS_CHAP_ERROR_RESTRICTED_LOGON_HOURS:
830 p = "E=646 Restricted logon hours";
833 case MS_CHAP_ERROR_ACCT_DISABLED:
834 p = "E=647 Account disabled";
837 case MS_CHAP_ERROR_PASSWD_EXPIRED:
838 p = "E=648 Password expired";
841 case MS_CHAP_ERROR_NO_DIALIN_PERMISSION:
842 p = "E=649 No dialin permission";
845 case MS_CHAP_ERROR_AUTHENTICATION_FAILURE:
846 p = "E=691 Authentication failure";
849 case MS_CHAP_ERROR_CHANGING_PASSWORD:
850 /* Should never see this, we don't support Change Password. */
851 p = "E=709 Error changing password";
856 p = msg = malloc(len + 33);
858 novm("ChapReceiveFailure");
861 slprintf(p, len + 33, "Unknown authentication failure: %.*s",
874 if (len > 0 && p != NULL)
877 error("CHAP authentication failed");
878 auth_withpeer_fail(cstate->unit, PPP_CHAP);
886 * ChapSendChallenge - Send an Authenticate challenge.
889 ChapSendChallenge(cstate)
893 int chal_len, name_len;
896 chal_len = cstate->chal_len;
897 name_len = strlen(cstate->chal_name);
898 outlen = CHAP_HEADERLEN + sizeof (u_char) + chal_len + name_len;
899 outp = outpacket_buf;
901 MAKEHEADER(outp, PPP_CHAP); /* paste in a CHAP header */
903 PUTCHAR(CHAP_CHALLENGE, outp);
904 PUTCHAR(cstate->chal_id, outp);
905 PUTSHORT(outlen, outp);
907 PUTCHAR(chal_len, outp); /* put length of challenge */
908 BCOPY(cstate->challenge, outp, chal_len);
909 INCPTR(chal_len, outp);
911 BCOPY(cstate->chal_name, outp, name_len); /* append hostname */
913 output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
915 TIMEOUT(ChapChallengeTimeout, cstate, cstate->timeouttime);
916 ++cstate->chal_transmits;
921 * ChapSendStatus - Send a status response (ack or nak).
922 * See RFC 2433 and RFC 2759 for MS-CHAP and MS-CHAPv2 message formats.
925 ChapSendStatus(cstate, code)
930 int i, outlen, msglen;
935 q = p + sizeof(msg); /* points 1 byte past msg */
937 if (code == CHAP_SUCCESS) {
939 if (cstate->chal_type == CHAP_MICROSOFT_V2) {
941 * Per RFC 2759, success message must be formatted as
942 * "S=<auth_string> M=<message>"
944 * <auth_string> is the Authenticator Response (mutual auth)
945 * <message> is a text message
947 * However, some versions of Windows (win98 tested) do not know
948 * about the M=<message> part (required per RFC 2759) and flag
949 * it as an error (reported incorrectly as an encryption error
950 * to the user). Since the RFC requires it, and it can be
951 * useful information, we supply it if the peer is a conforming
952 * system. Luckily (?), win98 sets the Flags field to 0x04
953 * (contrary to RFC requirements) so we can use that to
954 * distinguish between conforming and non-conforming systems.
956 * Special thanks to Alex Swiridov <say@real.kharkov.ua> for
957 * help debugging this.
959 slprintf(p, q - p, "S=");
961 slprintf(p, q - p, "%s", cstate->saresponse);
962 p += strlen(cstate->saresponse);
963 if (cstate->resp_flags != 0)
965 slprintf(p, q - p, " M=");
970 slprintf(p, q - p, "Welcome to %s.", hostname);
973 if ((cstate->chal_type == CHAP_MICROSOFT_V2) ||
974 (cstate->chal_type == CHAP_MICROSOFT)) {
976 * Failure message must be formatted as
977 * "E=e R=r C=c V=v M=m"
979 * e = error code (we use 691, ERROR_AUTHENTICATION_FAILURE)
980 * r = retry (we use 1, ok to retry)
981 * c = challenge to use for next response, we reuse previous
982 * v = Change Password version supported, we use 0
985 * The M=m part is only for MS-CHAPv2, but MS-CHAP should ignore
986 * any extra text according to RFC 2433. So we'll go the easy
987 * (read: lazy) route and include it always. Neither win2k nor
988 * win98 (others untested) display the message to the user anyway.
989 * They also both ignore the E=e code.
991 * Note that it's safe to reuse the same challenge as we don't
992 * actually accept another response based on the error message
993 * (and no clients try to resend a response anyway).
995 * Basically, this whole bit is useless code, even the small
996 * implementation here is only because of overspecification.
998 slprintf(p, q - p, "E=691 R=1 C=");
1000 for (i = 0; i < cstate->chal_len; i++)
1001 sprintf(p + i * 2, "%02X", cstate->challenge[i]);
1002 p += cstate->chal_len * 2;
1003 slprintf(p, q - p, " V=0 M=");
1008 slprintf(p, q - p, "I don't like you. Go 'way.");
1011 msglen = strlen(msg);
1013 outlen = CHAP_HEADERLEN + msglen;
1014 outp = outpacket_buf;
1016 MAKEHEADER(outp, PPP_CHAP); /* paste in a header */
1018 PUTCHAR(code, outp);
1019 PUTCHAR(cstate->chal_id, outp);
1020 PUTSHORT(outlen, outp);
1021 BCOPY(msg, outp, msglen);
1022 output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
1026 * ChapGenChallenge is used to generate a pseudo-random challenge string of
1027 * a pseudo-random length between min_len and max_len. The challenge
1028 * string and its length are stored in *cstate, and various other fields of
1029 * *cstate are initialized.
1033 ChapGenChallenge(cstate)
1036 int chal_len = 0; /* Avoid compiler warning */
1037 u_char *ptr = cstate->challenge;
1040 switch (cstate->chal_type) {
1041 case CHAP_DIGEST_MD5:
1043 * pick a random challenge length between MIN_CHALLENGE_LENGTH and
1044 * MAX_CHALLENGE_LENGTH
1046 chal_len = (unsigned) ((drand48() *
1047 (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
1048 MIN_CHALLENGE_LENGTH);
1052 case CHAP_MICROSOFT:
1053 /* MS-CHAP is fixed to an 8 octet challenge. */
1057 case CHAP_MICROSOFT_V2:
1058 /* MS-CHAPv2 is fixed to a 16 octet challenge. */
1063 fatal("ChapGenChallenge: Unsupported challenge type %d",
1064 (int) cstate->chal_type);
1068 cstate->chal_len = chal_len;
1069 cstate->chal_id = ++cstate->id;
1070 cstate->chal_transmits = 0;
1073 if (mschap_challenge)
1074 for (i = 0; i < chal_len; i++)
1075 *ptr++ = mschap_challenge[i];
1078 /* generate a random string */
1079 for (i = 0; i < chal_len; i++)
1080 *ptr++ = (char) (drand48() * 0xff);
1084 * ChapSendResponse - send a response packet with values as specified
1089 ChapSendResponse(cstate)
1093 int outlen, md_len, name_len;
1095 md_len = cstate->resp_length;
1096 name_len = strlen(cstate->resp_name);
1097 outlen = CHAP_HEADERLEN + sizeof (u_char) + md_len + name_len;
1098 outp = outpacket_buf;
1100 MAKEHEADER(outp, PPP_CHAP);
1102 PUTCHAR(CHAP_RESPONSE, outp); /* we are a response */
1103 PUTCHAR(cstate->resp_id, outp); /* copy id from challenge packet */
1104 PUTSHORT(outlen, outp); /* packet length */
1106 PUTCHAR(md_len, outp); /* length of MD */
1107 BCOPY(cstate->response, outp, md_len); /* copy MD to buffer */
1108 INCPTR(md_len, outp);
1110 BCOPY(cstate->resp_name, outp, name_len); /* append our name */
1112 /* send the packet */
1113 output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
1115 cstate->clientstate = CHAPCS_RESPONSE;
1116 TIMEOUT(ChapResponseTimeout, cstate, cstate->timeouttime);
1117 ++cstate->resp_transmits;
1121 * ChapPrintPkt - print the contents of a CHAP packet.
1123 static char *ChapCodenames[] = {
1124 "Challenge", "Response", "Success", "Failure"
1128 ChapPrintPkt(p, plen, printer, arg)
1131 void (*printer) __P((void *, char *, ...));
1138 if (plen < CHAP_HEADERLEN)
1143 if (len < CHAP_HEADERLEN || len > plen)
1146 if (code >= 1 && code <= sizeof(ChapCodenames) / sizeof(char *))
1147 printer(arg, " %s", ChapCodenames[code-1]);
1149 printer(arg, " code=0x%x", code);
1150 printer(arg, " id=0x%x", id);
1151 len -= CHAP_HEADERLEN;
1153 case CHAP_CHALLENGE:
1161 nlen = len - clen - 1;
1163 for (; clen > 0; --clen) {
1165 printer(arg, "%.2x", x);
1167 printer(arg, ">, name = ");
1168 print_string((char *)p, nlen, printer, arg);
1173 print_string((char *)p, len, printer, arg);
1176 for (clen = len; clen > 0; --clen) {
1178 printer(arg, " %.2x", x);
1182 return len + CHAP_HEADERLEN;