chap.c revision 23603 
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 1.10 1997/02/22 16:10:05 peter 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 "vars.h"
33#include "auth.h"
34
35static char *chapcodes[] = {
36  "???", "CHALLENGE", "RESPONSE", "SUCCESS", "FAILURE"
37};
38
39struct authinfo AuthChapInfo  = {
40  SendChapChallenge,
41};
42
43extern char *AuthGetSecret();
44extern int randinit;
45
46void
47ChapOutput(code, id, ptr, count)
48u_int code, id;
49u_char *ptr;
50int count;
51{
52  int plen;
53  struct fsmheader lh;
54  struct mbuf *bp;
55
56  plen =  sizeof(struct fsmheader) + count;
57  lh.code = code;
58  lh.id = id;
59  lh.length = htons(plen);
60  bp = mballoc(plen, MB_FSM);
61  bcopy(&lh, MBUF_CTOP(bp), sizeof(struct fsmheader));
62  if (count)
63    bcopy(ptr, MBUF_CTOP(bp) + sizeof(struct fsmheader), count);
64#ifdef DEBUG
65  DumpBp(bp);
66#endif
67  LogPrintf(LOG_LCP_BIT, "ChapOutput: %s\n", chapcodes[code]);
68  HdlcOutput(PRI_LINK, PROTO_CHAP, bp);
69}
70
71
72static char challenge_data[80];
73static int  challenge_len;
74
75void
76SendChapChallenge(chapid)
77int chapid;
78{
79  int len, i;
80  char *cp;
81
82  if (!randinit) {
83    srandom((unsigned)(time(NULL) ^ getpid()));
84    randinit = 1;
85  }
86
87  cp = challenge_data;
88  *cp++ = challenge_len = random() % 32 + 16;
89  for (i = 0; i < challenge_len; i++)
90    *cp++ = random() & 0xff;
91  len = strlen(VarAuthName);
92  bcopy(VarAuthName, cp, len);
93  cp += len;
94  ChapOutput(CHAP_CHALLENGE, chapid, challenge_data, cp - challenge_data);
95}
96
97#ifdef DEBUG
98void
99DumpDigest(mes, cp, len)
100char *mes;
101char *cp;
102int len;
103{
104  int i;
105
106  logprintf("%s: ", mes);
107  for (i = 0; i < len; i++) {
108    logprintf(" %02x", *cp++ & 0xff);
109  }
110  logprintf("\n");
111}
112#endif
113
114void
115RecvChapTalk(chp, bp)
116struct fsmheader *chp;
117struct mbuf *bp;
118{
119  int valsize, len;
120  int arglen, keylen, namelen;
121  char *cp, *argp, *ap, *name, *digest;
122  char *keyp;
123  MD5_CTX context;                            /* context */
124  char answer[100];
125  char cdigest[16];
126
127  len = ntohs(chp->length);
128#ifdef DEBUG
129  logprintf("length: %d\n", len);
130#endif
131  arglen = len - sizeof(struct fsmheader);
132  cp = (char *)MBUF_CTOP(bp);
133  valsize = *cp++ & 255;
134  name = cp + valsize;
135  namelen = arglen - valsize - 1;
136  name[namelen] = 0;
137  LogPrintf(LOG_PHASE_BIT, " Valsize = %d, Name = %s\n", valsize, name);
138
139  /*
140   * Get a secret key corresponds to the peer
141   */
142  keyp = AuthGetSecret(SECRETFILE, name, namelen, chp->code == CHAP_RESPONSE);
143
144  switch (chp->code) {
145  case CHAP_CHALLENGE:
146    if (keyp) {
147      keylen = strlen(keyp);
148    } else {
149      keylen = strlen(VarAuthKey);
150      keyp = VarAuthKey;
151    }
152    name = VarAuthName;
153    namelen = strlen(VarAuthName);
154    argp = malloc(1 + valsize + namelen + 16);
155    digest = argp;
156    *digest++ = 16;		/* value size */
157    ap = answer;
158    *ap++ = chp->id;
159    bcopy(keyp, ap, keylen);
160    ap += keylen;
161    bcopy(cp, ap, valsize);
162#ifdef DEBUG
163    DumpDigest("recv", ap, valsize);
164#endif
165    ap += valsize;
166    MD5Init(&context);
167    MD5Update(&context, answer, ap - answer);
168    MD5Final(digest, &context);
169#ifdef DEBUG
170    DumpDigest("answer", digest, 16);
171#endif
172    bcopy(name, digest + 16, namelen);
173    ap += namelen;
174    /* Send answer to the peer */
175    ChapOutput(CHAP_RESPONSE, chp->id, argp, namelen + 17);
176    free(argp);
177    break;
178  case CHAP_RESPONSE:
179    if (keyp) {
180      /*
181       * Compute correct digest value
182       */
183      keylen = strlen(keyp);
184      ap = answer;
185      *ap++ = chp->id;
186      bcopy(keyp, ap, keylen);
187      ap += keylen;
188      MD5Init(&context);
189      MD5Update(&context, answer, ap - answer);
190      MD5Update(&context, challenge_data+1, challenge_len);
191      MD5Final(cdigest, &context);
192#ifdef DEBUG
193      DumpDigest("got", cp, 16);
194      DumpDigest("expect", cdigest, 16);
195#endif
196      /*
197       * Compare with the response
198       */
199      if (bcmp(cp, cdigest, 16) == 0) {
200	ChapOutput(CHAP_SUCCESS, chp->id, "Wellcome!!", 10);
201	NewPhase(PHASE_NETWORK);
202	break;
203      }
204    }
205    /*
206     * Peer is not registerd, or response digest is wrong.
207     */
208    ChapOutput(CHAP_FAILURE, chp->id, "Invalid!!", 9);
209    LcpClose();
210    break;
211  }
212}
213
214void
215RecvChapResult(chp, bp)
216struct fsmheader *chp;
217struct mbuf *bp;
218{
219  int len;
220  struct lcpstate *lcp = &LcpInfo;
221
222  len = ntohs(chp->length);
223#ifdef DEBUG
224  logprintf("length: %d\n", len);
225#endif
226  if (chp->code == CHAP_SUCCESS) {
227    if (lcp->auth_iwait == PROTO_CHAP) {
228      lcp->auth_iwait = 0;
229      if (lcp->auth_ineed == 0)
230	NewPhase(PHASE_NETWORK);
231    }
232  } else {
233    /*
234     * Maybe, we shoud close LCP. Of cause, peer may take close action, too.
235     */
236    ;
237  }
238}
239
240void
241ChapInput(struct mbuf *bp)
242{
243  int len = plength(bp);
244  struct fsmheader *chp;
245
246  if (len >= sizeof(struct fsmheader)) {
247    chp = (struct fsmheader *)MBUF_CTOP(bp);
248    if (len >= ntohs(chp->length)) {
249      if (chp->code < 1 || chp->code > 4)
250	chp->code = 0;
251      LogPrintf(LOG_LCP_BIT, "ChapInput: %s\n", chapcodes[chp->code]);
252
253      bp->offset += sizeof(struct fsmheader);
254      bp->cnt -= sizeof(struct fsmheader);
255
256      switch (chp->code) {
257      case CHAP_RESPONSE:
258	StopAuthTimer(&AuthChapInfo);
259	/* Fall into.. */
260      case CHAP_CHALLENGE:
261	RecvChapTalk(chp, bp);
262	break;
263      case CHAP_SUCCESS:
264      case CHAP_FAILURE:
265	RecvChapResult(chp, bp);
266	break;
267      }
268    }
269  }
270  pfree(bp);
271}
272