BadVPN – Blame information for rev 1
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1 | office | 1 | /** |
2 | * @file |
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3 | * Additional SNMPv3 functionality RFC3414 and RFC3826. |
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4 | */ |
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5 | |||
6 | /* |
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7 | * Copyright (c) 2016 Elias Oenal. |
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8 | * All rights reserved. |
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9 | * |
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10 | * Redistribution and use in source and binary forms, with or without modification, |
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11 | * are permitted provided that the following conditions are met: |
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12 | * |
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13 | * 1. Redistributions of source code must retain the above copyright notice, |
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14 | * this list of conditions and the following disclaimer. |
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15 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
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16 | * this list of conditions and the following disclaimer in the documentation |
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17 | * and/or other materials provided with the distribution. |
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18 | * 3. The name of the author may not be used to endorse or promote products |
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19 | * derived from this software without specific prior written permission. |
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20 | * |
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21 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
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22 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
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23 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT |
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24 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
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26 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
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29 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY |
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30 | * OF SUCH DAMAGE. |
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31 | * |
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32 | * Author: Elias Oenal <lwip@eliasoenal.com> |
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33 | */ |
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34 | |||
35 | #include "snmpv3_priv.h" |
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36 | #include "lwip/apps/snmpv3.h" |
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37 | #include "lwip/sys.h" |
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38 | #include <string.h> |
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39 | |||
40 | #if LWIP_SNMP && LWIP_SNMP_V3 |
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41 | |||
42 | #ifdef LWIP_SNMPV3_INCLUDE_ENGINE |
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43 | #include LWIP_SNMPV3_INCLUDE_ENGINE |
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44 | #endif |
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45 | |||
46 | #define SNMP_MAX_TIME_BOOT 2147483647UL |
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47 | |||
48 | /** Call this if engine has been changed. Has to reset boots, see below */ |
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49 | void |
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50 | snmpv3_engine_id_changed(void) |
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51 | { |
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52 | snmpv3_set_engine_boots(0); |
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53 | } |
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54 | |||
55 | /** According to RFC3414 2.2.2. |
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56 | * |
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57 | * The number of times that the SNMP engine has |
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58 | * (re-)initialized itself since snmpEngineID |
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59 | * was last configured. |
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60 | */ |
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61 | s32_t |
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62 | snmpv3_get_engine_boots_internal(void) |
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63 | { |
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64 | if (snmpv3_get_engine_boots() == 0 || |
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65 | snmpv3_get_engine_boots() < SNMP_MAX_TIME_BOOT) { |
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66 | return snmpv3_get_engine_boots(); |
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67 | } |
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68 | |||
69 | snmpv3_set_engine_boots(SNMP_MAX_TIME_BOOT); |
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70 | return snmpv3_get_engine_boots(); |
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71 | } |
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72 | |||
73 | /** RFC3414 2.2.2. |
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74 | * |
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75 | * Once the timer reaches 2147483647 it gets reset to zero and the |
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76 | * engine boot ups get incremented. |
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77 | */ |
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78 | s32_t |
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79 | snmpv3_get_engine_time_internal(void) |
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80 | { |
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81 | if (snmpv3_get_engine_time() >= SNMP_MAX_TIME_BOOT) { |
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82 | snmpv3_reset_engine_time(); |
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83 | |||
84 | if (snmpv3_get_engine_boots() < SNMP_MAX_TIME_BOOT - 1) { |
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85 | snmpv3_set_engine_boots(snmpv3_get_engine_boots() + 1); |
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86 | } else { |
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87 | snmpv3_set_engine_boots(SNMP_MAX_TIME_BOOT); |
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88 | } |
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89 | } |
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90 | |||
91 | return snmpv3_get_engine_time(); |
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92 | } |
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93 | |||
94 | #if LWIP_SNMP_V3_CRYPTO |
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95 | |||
96 | /* This function ignores the byte order suggestion in RFC3414 |
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97 | * since it simply doesn't influence the effectiveness of an IV. |
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98 | * |
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99 | * Implementing RFC3826 priv param algorithm if LWIP_RAND is available. |
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100 | * |
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101 | * @todo: This is a potential thread safety issue. |
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102 | */ |
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103 | err_t |
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104 | snmpv3_build_priv_param(u8_t *priv_param) |
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105 | { |
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106 | #ifdef LWIP_RAND /* Based on RFC3826 */ |
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107 | static u8_t init; |
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108 | static u32_t priv1, priv2; |
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109 | |||
110 | /* Lazy initialisation */ |
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111 | if (init == 0) { |
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112 | init = 1; |
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113 | priv1 = LWIP_RAND(); |
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114 | priv2 = LWIP_RAND(); |
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115 | } |
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116 | |||
117 | SMEMCPY(&priv_param[0], &priv1, sizeof(priv1)); |
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118 | SMEMCPY(&priv_param[4], &priv2, sizeof(priv2)); |
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119 | |||
120 | /* Emulate 64bit increment */ |
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121 | priv1++; |
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122 | if (!priv1) { /* Overflow */ |
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123 | priv2++; |
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124 | } |
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125 | #else /* Based on RFC3414 */ |
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126 | static u32_t ctr; |
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127 | u32_t boots = snmpv3_get_engine_boots_internal(); |
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128 | SMEMCPY(&priv_param[0], &boots, 4); |
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129 | SMEMCPY(&priv_param[4], &ctr, 4); |
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130 | ctr++; |
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131 | #endif |
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132 | return ERR_OK; |
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133 | } |
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134 | #endif /* LWIP_SNMP_V3_CRYPTO */ |
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135 | |||
136 | #endif |