chap.c revision 28679 
1/*
2 *			PPP CHAP Module
3 *
4 *	    Written by Toshiharu OHNO (tony-o@iij.ad.jp)
5 *
6 *   Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd.
7 *
8 * Redistribution and use in source and binary forms are permitted
9 * provided that the above copyright notice and this paragraph are
10 * duplicated in all such forms and that any documentation,
11 * advertising materials, and other materials related to such
12 * distribution and use acknowledge that the software was developed
13 * by the Internet Initiative Japan, Inc.  The name of the
14 * IIJ may not be used to endorse or promote products derived
15 * from this software without specific prior written permission.
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 * $Id: chap.c,v 1.19 1997/06/14 00:21:23 ache Exp $
21 *
22 *	TODO:
23 */
24#include <sys/types.h>
25#include <time.h>
26#include "fsm.h"
27#include "chap.h"
28#include "lcpproto.h"
29#include "lcp.h"
30#include "hdlc.h"
31#include "phase.h"
32#include "loadalias.h"
33#include "vars.h"
34#include "auth.h"
35
36static char *chapcodes[] = {
37  "???", "CHALLENGE", "RESPONSE", "SUCCESS", "FAILURE"
38};
39
40struct authinfo AuthChapInfo = {
41  SendChapChallenge,
42};
43
44extern char *AuthGetSecret();
45extern int randinit;
46
47void
48ChapOutput(u_int code, u_int id, u_char * ptr, int count)
49{
50  int plen;
51  struct fsmheader lh;
52  struct mbuf *bp;
53
54  plen = sizeof(struct fsmheader) + count;
55  lh.code = code;
56  lh.id = id;
57  lh.length = htons(plen);
58  bp = mballoc(plen, MB_FSM);
59  bcopy(&lh, MBUF_CTOP(bp), sizeof(struct fsmheader));
60  if (count)
61    bcopy(ptr, MBUF_CTOP(bp) + sizeof(struct fsmheader), count);
62  LogDumpBp(LogDEBUG, "ChapOutput", bp);
63  LogPrintf(LogLCP, "ChapOutput: %s\n", chapcodes[code]);
64  HdlcOutput(PRI_LINK, PROTO_CHAP, bp);
65}
66
67
68static char challenge_data[80];
69static int challenge_len;
70
71void
72SendChapChallenge(int chapid)
73{
74  int len, i;
75  char *cp;
76
77  if (!randinit) {
78    randinit = 1;
79    srandomdev();
80  }
81  cp = challenge_data;
82  *cp++ = challenge_len = random() % 32 + 16;
83  for (i = 0; i < challenge_len; i++)
84    *cp++ = random() & 0xff;
85  len = strlen(VarAuthName);
86  bcopy(VarAuthName, cp, len);
87  cp += len;
88  ChapOutput(CHAP_CHALLENGE, chapid, challenge_data, cp - challenge_data);
89}
90
91void
92RecvChapTalk(struct fsmheader * chp, struct mbuf * bp)
93{
94  int valsize, len;
95  int arglen, keylen, namelen;
96  char *cp, *argp, *ap, *name, *digest;
97  char *keyp;
98  MD5_CTX context;		/* context */
99  char answer[100];
100  char cdigest[16];
101
102  len = ntohs(chp->length);
103  LogPrintf(LogDEBUG, "RecvChapTalk: length: %d\n", len);
104  arglen = len - sizeof(struct fsmheader);
105  cp = (char *) MBUF_CTOP(bp);
106  valsize = *cp++ & 255;
107  name = cp + valsize;
108  namelen = arglen - valsize - 1;
109  name[namelen] = 0;
110  LogPrintf(LogPHASE, " Valsize = %d, Name = %s\n", valsize, name);
111
112  /*
113   * Get a secret key corresponds to the peer
114   */
115  keyp = AuthGetSecret(SECRETFILE, name, namelen, chp->code == CHAP_RESPONSE);
116
117  switch (chp->code) {
118  case CHAP_CHALLENGE:
119    if (keyp) {
120      keylen = strlen(keyp);
121    } else {
122      keylen = strlen(VarAuthKey);
123      keyp = VarAuthKey;
124    }
125    name = VarAuthName;
126    namelen = strlen(VarAuthName);
127    argp = malloc(1 + valsize + namelen + 16);
128    if (argp == NULL) {
129      ChapOutput(CHAP_FAILURE, chp->id, "Out of memory!", 14);
130      return;
131    }
132    digest = argp;
133    *digest++ = 16;		/* value size */
134    ap = answer;
135    *ap++ = chp->id;
136    bcopy(keyp, ap, keylen);
137    ap += keylen;
138    bcopy(cp, ap, valsize);
139    LogDumpBuff(LogDEBUG, "recv", ap, valsize);
140    ap += valsize;
141    MD5Init(&context);
142    MD5Update(&context, answer, ap - answer);
143    MD5Final(digest, &context);
144    LogDumpBuff(LogDEBUG, "answer", digest, 16);
145    bcopy(name, digest + 16, namelen);
146    ap += namelen;
147    /* Send answer to the peer */
148    ChapOutput(CHAP_RESPONSE, chp->id, argp, namelen + 17);
149    free(argp);
150    break;
151  case CHAP_RESPONSE:
152    if (keyp) {
153
154      /*
155       * Compute correct digest value
156       */
157      keylen = strlen(keyp);
158      ap = answer;
159      *ap++ = chp->id;
160      bcopy(keyp, ap, keylen);
161      ap += keylen;
162      MD5Init(&context);
163      MD5Update(&context, answer, ap - answer);
164      MD5Update(&context, challenge_data + 1, challenge_len);
165      MD5Final(cdigest, &context);
166      LogDumpBuff(LogDEBUG, "got", cp, 16);
167      LogDumpBuff(LogDEBUG, "expect", cdigest, 16);
168
169      /*
170       * Compare with the response
171       */
172      if (bcmp(cp, cdigest, 16) == 0) {
173	ChapOutput(CHAP_SUCCESS, chp->id, "Wellcome!!", 10);
174	NewPhase(PHASE_NETWORK);
175	break;
176      }
177    }
178
179    /*
180     * Peer is not registerd, or response digest is wrong.
181     */
182    ChapOutput(CHAP_FAILURE, chp->id, "Invalid!!", 9);
183    reconnect(RECON_FALSE);
184    LcpClose();
185    break;
186  }
187}
188
189void
190RecvChapResult(struct fsmheader * chp, struct mbuf * bp)
191{
192  int len;
193  struct lcpstate *lcp = &LcpInfo;
194
195  len = ntohs(chp->length);
196  LogPrintf(LogDEBUG, "RecvChapResult: length: %d\n", len);
197  if (chp->code == CHAP_SUCCESS) {
198    if (lcp->auth_iwait == PROTO_CHAP) {
199      lcp->auth_iwait = 0;
200      if (lcp->auth_ineed == 0)
201	NewPhase(PHASE_NETWORK);
202    }
203  } else {
204
205    /*
206     * Maybe, we shoud close LCP. Of cause, peer may take close action, too.
207     */
208    ;
209  }
210}
211
212void
213ChapInput(struct mbuf * bp)
214{
215  int len = plength(bp);
216  struct fsmheader *chp;
217
218  if (len >= sizeof(struct fsmheader)) {
219    chp = (struct fsmheader *) MBUF_CTOP(bp);
220    if (len >= ntohs(chp->length)) {
221      if (chp->code < 1 || chp->code > 4)
222	chp->code = 0;
223      LogPrintf(LogLCP, "ChapInput: %s\n", chapcodes[chp->code]);
224
225      bp->offset += sizeof(struct fsmheader);
226      bp->cnt -= sizeof(struct fsmheader);
227
228      switch (chp->code) {
229      case CHAP_RESPONSE:
230	StopAuthTimer(&AuthChapInfo);
231	/* Fall into.. */
232      case CHAP_CHALLENGE:
233	RecvChapTalk(chp, bp);
234	break;
235      case CHAP_SUCCESS:
236      case CHAP_FAILURE:
237	RecvChapResult(chp, bp);
238	break;
239      }
240    }
241  }
242  pfree(bp);
243}
244