[457] | 1 | /**
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| 2 | * @file
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| 3 | * Additional SNMPv3 functionality RFC3414 and RFC3826.
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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 | */
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| 34 |
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| 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 |
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| 40 | #if LWIP_SNMP && LWIP_SNMP_V3
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| 41 |
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| 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 |
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| 46 | #define SNMP_MAX_TIME_BOOT 2147483647UL
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| 47 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 91 | return snmpv3_get_engine_time();
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| 92 | }
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| 93 |
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| 94 | #if LWIP_SNMP_V3_CRYPTO
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| 95 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 136 | #endif
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