1 | /**
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2 | * @file
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3 | * Dummy SNMPv3 functions.
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4 | */
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5 |
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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 | * Dirk Ziegelmeier <dirk@ziegelmeier.net>
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34 | */
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35 |
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36 | #include "lwip/apps/snmpv3.h"
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37 | #include "snmpv3_dummy.h"
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38 | #include <string.h>
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39 | #include "lwip/err.h"
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40 | #include "lwip/def.h"
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41 | #include "lwip/timeouts.h"
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42 |
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43 | #if LWIP_SNMP && LWIP_SNMP_V3
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44 |
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45 | struct user_table_entry {
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46 | char username[32];
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47 | snmpv3_auth_algo_t auth_algo;
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48 | u8_t auth_key[20];
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49 | snmpv3_priv_algo_t priv_algo;
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50 | u8_t priv_key[20];
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51 | };
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52 |
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53 | static struct user_table_entry user_table[] = {
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54 | { "lwip", SNMP_V3_AUTH_ALGO_INVAL, "" , SNMP_V3_PRIV_ALGO_INVAL, "" },
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55 | { "piwl", SNMP_V3_AUTH_ALGO_INVAL, "" , SNMP_V3_PRIV_ALGO_INVAL, "" },
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56 | { "test", SNMP_V3_AUTH_ALGO_INVAL, "" , SNMP_V3_PRIV_ALGO_INVAL, "" }
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57 | };
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58 |
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59 | static char snmpv3_engineid[32];
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60 | static u8_t snmpv3_engineid_len;
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61 |
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62 | static u32_t enginetime = 0;
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63 |
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64 | /* In this implementation engineboots is volatile. In a real world application this value should be stored in non-volatile memory.*/
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65 | static u32_t engineboots = 0;
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66 |
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67 | /**
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68 | * @brief Get the user table entry for the given username.
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69 | *
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70 | * @param[in] username pointer to the username
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71 | *
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72 | * @return pointer to the user table entry or NULL if not found.
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73 | */
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74 | static struct user_table_entry*
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75 | get_user(const char *username)
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76 | {
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77 | size_t i;
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78 |
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79 | for (i = 0; i < LWIP_ARRAYSIZE(user_table); i++) {
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80 | if (strnlen(username, 32) != strnlen(user_table[i].username, 32)) {
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81 | continue;
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82 | }
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83 |
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84 | if (memcmp(username, user_table[i].username, strnlen(username, 32)) == 0) {
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85 | return &user_table[i];
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86 | }
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87 | }
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88 |
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89 | return NULL;
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90 | }
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91 |
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92 | u8_t
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93 | snmpv3_get_amount_of_users(void)
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94 | {
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95 | return LWIP_ARRAYSIZE(user_table);
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96 | }
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97 |
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98 | /**
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99 | * @brief Get the username of a user number (index)
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100 | * @param username is a pointer to a string.
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101 | * @param index is the user index.
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102 | * @return ERR_OK if user is found, ERR_VAL is user is not found.
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103 | */
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104 | err_t
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105 | snmpv3_get_username(char *username, u8_t index)
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106 | {
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107 | if (index < LWIP_ARRAYSIZE(user_table)) {
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108 | MEMCPY(username, user_table[index].username, sizeof(user_table[0].username));
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109 | return ERR_OK;
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110 | }
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111 |
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112 | return ERR_VAL;
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113 | }
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114 |
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115 | /**
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116 | * Timer callback function that increments enginetime and reschedules itself.
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117 | *
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118 | * @param arg unused argument
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119 | */
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120 | static void
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121 | snmpv3_enginetime_timer(void *arg)
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122 | {
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123 | LWIP_UNUSED_ARG(arg);
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124 |
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125 | enginetime++;
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126 |
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127 | /* This handles the engine time reset */
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128 | snmpv3_get_engine_time_internal();
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129 |
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130 | /* restart timer */
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131 | sys_timeout(1000, snmpv3_enginetime_timer, NULL);
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132 | }
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133 |
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134 | err_t
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135 | snmpv3_set_user_auth_algo(const char *username, snmpv3_auth_algo_t algo)
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136 | {
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137 | struct user_table_entry *p = get_user(username);
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138 |
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139 | if (p) {
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140 | switch (algo) {
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141 | case SNMP_V3_AUTH_ALGO_INVAL:
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142 | if (p->priv_algo != SNMP_V3_PRIV_ALGO_INVAL) {
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143 | /* Privacy MUST be disabled before configuring authentication */
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144 | break;
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145 | } else {
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146 | p->auth_algo = algo;
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147 | return ERR_OK;
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148 | }
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149 | #if LWIP_SNMP_V3_CRYPTO
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150 | case SNMP_V3_AUTH_ALGO_MD5:
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151 | case SNMP_V3_AUTH_ALGO_SHA:
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152 | #endif
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153 | p->auth_algo = algo;
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154 | return ERR_OK;
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155 | default:
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156 | break;
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157 | }
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158 | }
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159 |
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160 | return ERR_VAL;
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161 | }
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162 |
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163 | err_t
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164 | snmpv3_set_user_priv_algo(const char *username, snmpv3_priv_algo_t algo)
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165 | {
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166 | struct user_table_entry *p = get_user(username);
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167 |
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168 | if (p) {
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169 | switch (algo) {
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170 | #if LWIP_SNMP_V3_CRYPTO
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171 | case SNMP_V3_PRIV_ALGO_AES:
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172 | case SNMP_V3_PRIV_ALGO_DES:
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173 | if (p->auth_algo == SNMP_V3_AUTH_ALGO_INVAL) {
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174 | /* Authentication MUST be enabled before configuring privacy */
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175 | break;
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176 | } else {
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177 | p->priv_algo = algo;
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178 | return ERR_OK;
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179 | }
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180 | #endif
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181 | case SNMP_V3_PRIV_ALGO_INVAL:
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182 | p->priv_algo = algo;
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183 | return ERR_OK;
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184 | default:
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185 | break;
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186 | }
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187 | }
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188 |
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189 | return ERR_VAL;
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190 | }
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191 |
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192 | err_t
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193 | snmpv3_set_user_auth_key(const char *username, const char *password)
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194 | {
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195 | struct user_table_entry *p = get_user(username);
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196 | const char *engineid;
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197 | u8_t engineid_len;
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198 |
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199 | if (p) {
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200 | /* password should be at least 8 characters long */
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201 | if (strlen(password) >= 8) {
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202 | memset(p->auth_key, 0, sizeof(p->auth_key));
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203 | snmpv3_get_engine_id(&engineid, &engineid_len);
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204 | switch (p->auth_algo) {
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205 | case SNMP_V3_AUTH_ALGO_INVAL:
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206 | return ERR_OK;
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207 | #if LWIP_SNMP_V3_CRYPTO
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208 | case SNMP_V3_AUTH_ALGO_MD5:
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209 | snmpv3_password_to_key_md5((const u8_t*)password, strlen(password), (const u8_t*)engineid, engineid_len, p->auth_key);
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210 | return ERR_OK;
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211 | case SNMP_V3_AUTH_ALGO_SHA:
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212 | snmpv3_password_to_key_sha((const u8_t*)password, strlen(password), (const u8_t*)engineid, engineid_len, p->auth_key);
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213 | return ERR_OK;
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214 | #endif
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215 | default:
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216 | return ERR_VAL;
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217 | }
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218 | }
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219 | }
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220 |
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221 | return ERR_VAL;
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222 | }
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223 |
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224 | err_t
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225 | snmpv3_set_user_priv_key(const char *username, const char *password)
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226 | {
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227 | struct user_table_entry *p = get_user(username);
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228 | const char *engineid;
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229 | u8_t engineid_len;
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230 |
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231 | if (p) {
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232 | /* password should be at least 8 characters long */
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233 | if (strlen(password) >= 8) {
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234 | memset(p->priv_key, 0, sizeof(p->priv_key));
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235 | snmpv3_get_engine_id(&engineid, &engineid_len);
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236 | switch (p->auth_algo) {
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237 | case SNMP_V3_AUTH_ALGO_INVAL:
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238 | return ERR_OK;
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239 | #if LWIP_SNMP_V3_CRYPTO
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240 | case SNMP_V3_AUTH_ALGO_MD5:
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241 | snmpv3_password_to_key_md5((const u8_t*)password, strlen(password), (const u8_t*)engineid, engineid_len, p->priv_key);
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242 | return ERR_OK;
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243 | case SNMP_V3_AUTH_ALGO_SHA:
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244 | snmpv3_password_to_key_sha((const u8_t*)password, strlen(password), (const u8_t*)engineid, engineid_len, p->priv_key);
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245 | return ERR_OK;
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246 | #endif
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247 | default:
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248 | return ERR_VAL;
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249 | }
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250 | }
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251 | }
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252 |
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253 | return ERR_VAL;
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254 | }
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255 |
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256 | /**
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257 | * @brief Get the storage type of the given username.
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258 | *
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259 | * @param[in] username pointer to the username
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260 | * @param[out] type the storage type
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261 | *
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262 | * @return ERR_OK if the user was found, ERR_VAL if not.
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263 | */
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264 | err_t
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265 | snmpv3_get_user_storagetype(const char *username, snmpv3_user_storagetype_t *type)
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266 | {
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267 | if (get_user(username) != NULL) {
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268 | /* Found user in user table
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269 | * In this dummy implementation, storage is permanent because no user can be deleted.
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270 | * All changes to users are lost after a reboot.*/
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271 | *type = SNMP_V3_USER_STORAGETYPE_PERMANENT;
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272 | return ERR_OK;
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273 | }
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274 |
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275 | return ERR_VAL;
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276 | }
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277 |
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278 | /**
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279 | * @param username is a pointer to a string.
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280 | * @param auth_algo is a pointer to u8_t. The implementation has to set this if user was found.
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281 | * @param auth_key is a pointer to a pointer to a string. Implementation has to set this if user was found.
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282 | * @param priv_algo is a pointer to u8_t. The implementation has to set this if user was found.
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283 | * @param priv_key is a pointer to a pointer to a string. Implementation has to set this if user was found.
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284 | */
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285 | err_t
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286 | snmpv3_get_user(const char* username, snmpv3_auth_algo_t *auth_algo, u8_t *auth_key, snmpv3_priv_algo_t *priv_algo, u8_t *priv_key)
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287 | {
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288 | const struct user_table_entry *p;
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289 |
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290 | /* The msgUserName specifies the user (principal) on whose behalf the
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291 | message is being exchanged. Note that a zero-length userName will
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292 | not match any user, but it can be used for snmpEngineID discovery. */
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293 | if(strlen(username) == 0) {
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294 | return ERR_OK;
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295 | }
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296 |
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297 | p = get_user(username);
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298 |
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299 | if (!p) {
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300 | return ERR_VAL;
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301 | }
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302 |
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303 | if (auth_algo != NULL) {
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304 | *auth_algo = p->auth_algo;
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305 | }
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306 | if(auth_key != NULL) {
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307 | MEMCPY(auth_key, p->auth_key, sizeof(p->auth_key));
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308 | }
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309 | if (priv_algo != NULL) {
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310 | *priv_algo = p->priv_algo;
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311 | }
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312 | if(priv_key != NULL) {
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313 | MEMCPY(priv_key, p->priv_key, sizeof(p->priv_key));
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314 | }
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315 | return ERR_OK;
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316 | }
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317 |
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318 | /**
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319 | * Get engine ID from persistence
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320 | */
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321 | void
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322 | snmpv3_get_engine_id(const char **id, u8_t *len)
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323 | {
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324 | *id = snmpv3_engineid;
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325 | *len = snmpv3_engineid_len;
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326 | }
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327 |
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328 | /**
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329 | * Store engine ID in persistence
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330 | */
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331 | err_t
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332 | snmpv3_set_engine_id(const char *id, u8_t len)
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333 | {
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334 | MEMCPY(snmpv3_engineid, id, len);
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335 | snmpv3_engineid_len = len;
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336 | return ERR_OK;
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337 | }
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338 |
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339 | /**
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340 | * Get engine boots from persistence. Must be increased on each boot.
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341 | */
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342 | u32_t
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343 | snmpv3_get_engine_boots(void)
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344 | {
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345 | return engineboots;
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346 | }
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347 |
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348 | /**
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349 | * Store engine boots in persistence
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350 | */
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351 | void
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352 | snmpv3_set_engine_boots(u32_t boots)
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353 | {
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354 | engineboots = boots;
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355 | }
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356 |
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357 | /**
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358 | * RFC3414 2.2.2.
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359 | * Once the timer reaches 2147483647 it gets reset to zero and the
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360 | * engine boot ups get incremented.
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361 | */
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362 | u32_t
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363 | snmpv3_get_engine_time(void)
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364 | {
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365 | return enginetime;
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366 | }
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367 |
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368 | /**
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369 | * Reset current engine time to 0
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370 | */
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371 | void
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372 | snmpv3_reset_engine_time(void)
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373 | {
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374 | enginetime = 0;
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375 | }
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376 |
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377 | /**
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378 | * Initialize dummy SNMPv3 implementation
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379 | */
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380 | void
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381 | snmpv3_dummy_init(void)
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382 | {
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383 | snmpv3_set_engine_id("FOO", 3);
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384 |
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385 | snmpv3_set_user_auth_algo("lwip", SNMP_V3_AUTH_ALGO_SHA);
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386 | snmpv3_set_user_auth_key("lwip", "maplesyrup");
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387 |
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388 | snmpv3_set_user_priv_algo("lwip", SNMP_V3_PRIV_ALGO_DES);
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389 | snmpv3_set_user_priv_key("lwip", "maplesyrup");
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390 |
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391 | /* Start the engine time timer */
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392 | snmpv3_enginetime_timer(NULL);
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393 | }
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394 |
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395 | #endif /* LWIP_SNMP && LWIP_SNMP_V3 */
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