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1 office 1 /*
2 * chap-md5.c - New CHAP/MD5 implementation.
3 *
4 * Copyright (c) 2003 Paul Mackerras. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * 2. The name(s) of the authors of this software must not be used to
14 * endorse or promote products derived from this software without
15 * prior written permission.
16 *
17 * 3. Redistributions of any form whatsoever must retain the following
18 * acknowledgment:
19 * "This product includes software developed by Paul Mackerras
20 * <paulus@samba.org>".
21 *
22 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
23 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
24 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
25 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
26 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
27 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
28 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
29 */
30  
31 #include "netif/ppp/ppp_opts.h"
32 #if PPP_SUPPORT && CHAP_SUPPORT /* don't build if not configured for use in lwipopts.h */
33  
34 #if 0 /* UNUSED */
35 #include <stdlib.h>
36 #include <string.h>
37 #endif /* UNUSED */
38  
39 #include "netif/ppp/ppp_impl.h"
40  
41 #include "netif/ppp/chap-new.h"
42 #include "netif/ppp/chap-md5.h"
43 #include "netif/ppp/magic.h"
44 #include "netif/ppp/pppcrypt.h"
45  
46 #define MD5_HASH_SIZE 16
47 #define MD5_MIN_CHALLENGE 17
48 #define MD5_MAX_CHALLENGE 24
49 #define MD5_MIN_MAX_POWER_OF_TWO_CHALLENGE 3 /* 2^3-1 = 7, 17+7 = 24 */
50  
51 #if PPP_SERVER
52 static void chap_md5_generate_challenge(ppp_pcb *pcb, unsigned char *cp) {
53 int clen;
54 LWIP_UNUSED_ARG(pcb);
55  
56 clen = MD5_MIN_CHALLENGE + magic_pow(MD5_MIN_MAX_POWER_OF_TWO_CHALLENGE);
57 *cp++ = clen;
58 magic_random_bytes(cp, clen);
59 }
60  
61 static int chap_md5_verify_response(ppp_pcb *pcb, int id, const char *name,
62 const unsigned char *secret, int secret_len,
63 const unsigned char *challenge, const unsigned char *response,
64 char *message, int message_space) {
65 lwip_md5_context ctx;
66 unsigned char idbyte = id;
67 unsigned char hash[MD5_HASH_SIZE];
68 int challenge_len, response_len;
69 LWIP_UNUSED_ARG(name);
70 LWIP_UNUSED_ARG(pcb);
71  
72 challenge_len = *challenge++;
73 response_len = *response++;
74 if (response_len == MD5_HASH_SIZE) {
75 /* Generate hash of ID, secret, challenge */
76 lwip_md5_init(&ctx);
77 lwip_md5_starts(&ctx);
78 lwip_md5_update(&ctx, &idbyte, 1);
79 lwip_md5_update(&ctx, secret, secret_len);
80 lwip_md5_update(&ctx, challenge, challenge_len);
81 lwip_md5_finish(&ctx, hash);
82 lwip_md5_free(&ctx);
83  
84 /* Test if our hash matches the peer's response */
85 if (memcmp(hash, response, MD5_HASH_SIZE) == 0) {
86 ppp_slprintf(message, message_space, "Access granted");
87 return 1;
88 }
89 }
90 ppp_slprintf(message, message_space, "Access denied");
91 return 0;
92 }
93 #endif /* PPP_SERVER */
94  
95 static void chap_md5_make_response(ppp_pcb *pcb, unsigned char *response, int id, const char *our_name,
96 const unsigned char *challenge, const char *secret, int secret_len,
97 unsigned char *private_) {
98 lwip_md5_context ctx;
99 unsigned char idbyte = id;
100 int challenge_len = *challenge++;
101 LWIP_UNUSED_ARG(our_name);
102 LWIP_UNUSED_ARG(private_);
103 LWIP_UNUSED_ARG(pcb);
104  
105 lwip_md5_init(&ctx);
106 lwip_md5_starts(&ctx);
107 lwip_md5_update(&ctx, &idbyte, 1);
108 lwip_md5_update(&ctx, (const u_char *)secret, secret_len);
109 lwip_md5_update(&ctx, challenge, challenge_len);
110 lwip_md5_finish(&ctx, &response[1]);
111 lwip_md5_free(&ctx);
112 response[0] = MD5_HASH_SIZE;
113 }
114  
115 const struct chap_digest_type md5_digest = {
116 CHAP_MD5, /* code */
117 #if PPP_SERVER
118 chap_md5_generate_challenge,
119 chap_md5_verify_response,
120 #endif /* PPP_SERVER */
121 chap_md5_make_response,
122 NULL, /* check_success */
123 NULL, /* handle_failure */
124 };
125  
126 #endif /* PPP_SUPPORT && CHAP_SUPPORT */