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