[457] | 1 | /**
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| 2 | * @file
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| 3 | * Abstract Syntax Notation One (ISO 8824, 8825) encoding
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| 4 | *
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| 5 | * @todo not optimised (yet), favor correctness over speed, favor speed over size
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| 6 | */
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| 7 |
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| 8 | /*
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| 9 | * Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
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| 10 | * All rights reserved.
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| 11 | *
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| 12 | * Redistribution and use in source and binary forms, with or without modification,
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| 13 | * are permitted provided that the following conditions are met:
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| 14 | *
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| 15 | * 1. Redistributions of source code must retain the above copyright notice,
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| 16 | * this list of conditions and the following disclaimer.
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| 17 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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| 18 | * this list of conditions and the following disclaimer in the documentation
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| 19 | * and/or other materials provided with the distribution.
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| 20 | * 3. The name of the author may not be used to endorse or promote products
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| 21 | * derived from this software without specific prior written permission.
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| 22 | *
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| 23 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 24 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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| 25 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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| 26 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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| 27 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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| 28 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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| 29 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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| 30 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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| 31 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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| 32 | * OF SUCH DAMAGE.
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| 33 | *
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| 34 | * Author: Christiaan Simons <christiaan.simons@axon.tv>
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| 35 | * Martin Hentschel <info@cl-soft.de>
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| 36 | */
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| 37 |
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| 38 | #include "lwip/apps/snmp_opts.h"
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| 39 |
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| 40 | #if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
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| 41 |
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| 42 | #include "snmp_asn1.h"
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| 43 |
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| 44 | #define PBUF_OP_EXEC(code) \
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| 45 | if ((code) != ERR_OK) { \
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| 46 | return ERR_BUF; \
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| 47 | }
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| 48 |
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| 49 | /**
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| 50 | * Encodes a TLV into a pbuf stream.
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| 51 | *
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| 52 | * @param pbuf_stream points to a pbuf stream
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| 53 | * @param tlv TLV to encode
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| 54 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
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| 55 | */
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| 56 | err_t
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| 57 | snmp_ans1_enc_tlv(struct snmp_pbuf_stream *pbuf_stream, struct snmp_asn1_tlv *tlv)
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| 58 | {
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| 59 | u8_t data;
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| 60 | u8_t length_bytes_required;
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| 61 |
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| 62 | /* write type */
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| 63 | if ((tlv->type & SNMP_ASN1_DATATYPE_MASK) == SNMP_ASN1_DATATYPE_EXTENDED) {
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| 64 | /* extended format is not used by SNMP so we do not accept those values */
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| 65 | return ERR_ARG;
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| 66 | }
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| 67 | if (tlv->type_len != 0) {
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| 68 | /* any other value as auto is not accepted for type (we always use one byte because extended syntax is prohibited) */
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| 69 | return ERR_ARG;
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| 70 | }
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| 71 |
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| 72 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, tlv->type));
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| 73 | tlv->type_len = 1;
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| 74 |
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| 75 | /* write length */
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| 76 | if (tlv->value_len <= 127) {
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| 77 | length_bytes_required = 1;
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| 78 | } else if (tlv->value_len <= 255) {
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| 79 | length_bytes_required = 2;
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| 80 | } else {
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| 81 | length_bytes_required = 3;
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| 82 | }
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| 83 |
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| 84 | /* check for forced min length */
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| 85 | if (tlv->length_len > 0) {
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| 86 | if (tlv->length_len < length_bytes_required) {
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| 87 | /* unable to code requested length in requested number of bytes */
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| 88 | return ERR_ARG;
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| 89 | }
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| 90 |
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| 91 | length_bytes_required = tlv->length_len;
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| 92 | } else {
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| 93 | tlv->length_len = length_bytes_required;
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| 94 | }
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| 95 |
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| 96 | if (length_bytes_required > 1) {
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| 97 | /* multi byte representation required */
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| 98 | length_bytes_required--;
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| 99 | data = 0x80 | length_bytes_required; /* extended length definition, 1 length byte follows */
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| 100 |
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| 101 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, data));
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| 102 |
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| 103 | while (length_bytes_required > 1) {
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| 104 | if (length_bytes_required == 2) {
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| 105 | /* append high byte */
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| 106 | data = (u8_t)(tlv->value_len >> 8);
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| 107 | } else {
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| 108 | /* append leading 0x00 */
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| 109 | data = 0x00;
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| 110 | }
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| 111 |
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| 112 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, data));
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| 113 | length_bytes_required--;
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| 114 | }
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| 115 | }
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| 116 |
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| 117 | /* append low byte */
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| 118 | data = (u8_t)(tlv->value_len & 0xFF);
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| 119 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, data));
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| 120 |
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| 121 | return ERR_OK;
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| 122 | }
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| 123 |
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| 124 | /**
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| 125 | * Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg.
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| 126 | *
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| 127 | * @param pbuf_stream points to a pbuf stream
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| 128 | * @param raw_len raw data length
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| 129 | * @param raw points raw data
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| 130 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
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| 131 | */
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| 132 | err_t
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| 133 | snmp_asn1_enc_raw(struct snmp_pbuf_stream *pbuf_stream, const u8_t *raw, u16_t raw_len)
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| 134 | {
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| 135 | PBUF_OP_EXEC(snmp_pbuf_stream_writebuf(pbuf_stream, raw, raw_len));
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| 136 |
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| 137 | return ERR_OK;
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| 138 | }
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| 139 |
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| 140 | /**
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| 141 | * Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg.
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| 142 | *
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| 143 | * @param pbuf_stream points to a pbuf stream
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| 144 | * @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
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| 145 | * @param value is the host order u32_t value to be encoded
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| 146 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
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| 147 | *
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| 148 | * @see snmp_asn1_enc_u32t_cnt()
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| 149 | */
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| 150 | err_t
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| 151 | snmp_asn1_enc_u32t(struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, u32_t value)
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| 152 | {
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| 153 | if (octets_needed > 5) {
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| 154 | return ERR_ARG;
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| 155 | }
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| 156 | if (octets_needed == 5) {
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| 157 | /* not enough bits in 'value' add leading 0x00 */
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| 158 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, 0x00));
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| 159 | octets_needed--;
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| 160 | }
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| 161 |
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| 162 | while (octets_needed > 1) {
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| 163 | octets_needed--;
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| 164 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value >> (octets_needed << 3))));
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| 165 | }
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| 166 |
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| 167 | /* (only) one least significant octet */
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| 168 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)value));
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| 169 |
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| 170 | return ERR_OK;
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| 171 | }
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| 172 | /**
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| 173 | * Encodes s32_t integer into a pbuf chained ASN1 msg.
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| 174 | *
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| 175 | * @param pbuf_stream points to a pbuf stream
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| 176 | * @param octets_needed encoding length (from snmp_asn1_enc_s32t_cnt())
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| 177 | * @param value is the host order s32_t value to be encoded
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| 178 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
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| 179 | *
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| 180 | * @see snmp_asn1_enc_s32t_cnt()
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| 181 | */
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| 182 | err_t
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| 183 | snmp_asn1_enc_s32t(struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, s32_t value)
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| 184 | {
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| 185 | while (octets_needed > 1) {
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| 186 | octets_needed--;
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| 187 |
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| 188 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value >> (octets_needed << 3))));
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| 189 | }
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| 190 |
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| 191 | /* (only) one least significant octet */
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| 192 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)value));
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| 193 |
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| 194 | return ERR_OK;
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| 195 | }
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| 196 |
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| 197 | /**
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| 198 | * Encodes object identifier into a pbuf chained ASN1 msg.
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| 199 | *
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| 200 | * @param pbuf_stream points to a pbuf stream
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| 201 | * @param oid points to object identifier array
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| 202 | * @param oid_len object identifier array length
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| 203 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
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| 204 | */
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| 205 | err_t
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| 206 | snmp_asn1_enc_oid(struct snmp_pbuf_stream *pbuf_stream, const u32_t *oid, u16_t oid_len)
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| 207 | {
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| 208 | if (oid_len > 1) {
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| 209 | /* write compressed first two sub id's */
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| 210 | u32_t compressed_byte = ((oid[0] * 40) + oid[1]);
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| 211 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)compressed_byte));
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| 212 | oid_len -= 2;
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| 213 | oid += 2;
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| 214 | } else {
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| 215 | /* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */
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| 216 | /* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */
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| 217 | return ERR_ARG;
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| 218 | }
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| 219 |
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| 220 | while (oid_len > 0) {
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| 221 | u32_t sub_id;
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| 222 | u8_t shift, tail;
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| 223 |
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| 224 | oid_len--;
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| 225 | sub_id = *oid;
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| 226 | tail = 0;
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| 227 | shift = 28;
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| 228 | while (shift > 0) {
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| 229 | u8_t code;
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| 230 |
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| 231 | code = (u8_t)(sub_id >> shift);
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| 232 | if ((code != 0) || (tail != 0)) {
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| 233 | tail = 1;
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| 234 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, code | 0x80));
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| 235 | }
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| 236 | shift -= 7;
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| 237 | }
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| 238 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)sub_id & 0x7F));
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| 239 |
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| 240 | /* proceed to next sub-identifier */
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| 241 | oid++;
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| 242 | }
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| 243 | return ERR_OK;
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| 244 | }
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| 245 |
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| 246 | /**
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| 247 | * Returns octet count for length.
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| 248 | *
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| 249 | * @param length parameter length
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| 250 | * @param octets_needed points to the return value
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| 251 | */
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| 252 | void
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| 253 | snmp_asn1_enc_length_cnt(u16_t length, u8_t *octets_needed)
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| 254 | {
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| 255 | if (length < 0x80U) {
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| 256 | *octets_needed = 1;
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| 257 | } else if (length < 0x100U) {
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| 258 | *octets_needed = 2;
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| 259 | } else {
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| 260 | *octets_needed = 3;
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| 261 | }
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| 262 | }
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| 263 |
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| 264 | /**
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| 265 | * Returns octet count for an u32_t.
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| 266 | *
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| 267 | * @param value value to be encoded
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| 268 | * @param octets_needed points to the return value
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| 269 | *
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| 270 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
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| 271 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
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| 272 | * of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
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| 273 | */
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| 274 | void
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| 275 | snmp_asn1_enc_u32t_cnt(u32_t value, u16_t *octets_needed)
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| 276 | {
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| 277 | if (value < 0x80UL) {
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| 278 | *octets_needed = 1;
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| 279 | } else if (value < 0x8000UL) {
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| 280 | *octets_needed = 2;
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| 281 | } else if (value < 0x800000UL) {
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| 282 | *octets_needed = 3;
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| 283 | } else if (value < 0x80000000UL) {
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| 284 | *octets_needed = 4;
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| 285 | } else {
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| 286 | *octets_needed = 5;
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| 287 | }
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| 288 | }
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| 289 |
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| 290 | /**
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| 291 | * Returns octet count for an s32_t.
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| 292 | *
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| 293 | * @param value value to be encoded
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| 294 | * @param octets_needed points to the return value
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| 295 | *
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| 296 | * @note ASN coded integers are _always_ signed.
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| 297 | */
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| 298 | void
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| 299 | snmp_asn1_enc_s32t_cnt(s32_t value, u16_t *octets_needed)
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| 300 | {
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| 301 | if (value < 0) {
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| 302 | value = ~value;
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| 303 | }
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| 304 | if (value < 0x80L) {
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| 305 | *octets_needed = 1;
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| 306 | } else if (value < 0x8000L) {
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| 307 | *octets_needed = 2;
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| 308 | } else if (value < 0x800000L) {
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| 309 | *octets_needed = 3;
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| 310 | } else {
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| 311 | *octets_needed = 4;
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| 312 | }
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| 313 | }
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| 314 |
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| 315 | /**
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| 316 | * Returns octet count for an object identifier.
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| 317 | *
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| 318 | * @param oid points to object identifier array
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| 319 | * @param oid_len object identifier array length
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| 320 | * @param octets_needed points to the return value
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| 321 | */
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| 322 | void
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| 323 | snmp_asn1_enc_oid_cnt(const u32_t *oid, u16_t oid_len, u16_t *octets_needed)
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| 324 | {
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| 325 | u32_t sub_id;
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| 326 |
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| 327 | *octets_needed = 0;
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| 328 | if (oid_len > 1) {
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| 329 | /* compressed prefix in one octet */
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| 330 | (*octets_needed)++;
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| 331 | oid_len -= 2;
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| 332 | oid += 2;
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| 333 | }
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| 334 | while (oid_len > 0) {
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| 335 | oid_len--;
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| 336 | sub_id = *oid;
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| 337 |
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| 338 | sub_id >>= 7;
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| 339 | (*octets_needed)++;
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| 340 | while (sub_id > 0) {
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| 341 | sub_id >>= 7;
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| 342 | (*octets_needed)++;
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| 343 | }
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| 344 | oid++;
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| 345 | }
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| 346 | }
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| 347 |
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| 348 | /**
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| 349 | * Decodes a TLV from a pbuf stream.
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| 350 | *
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| 351 | * @param pbuf_stream points to a pbuf stream
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| 352 | * @param tlv returns decoded TLV
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| 353 | * @return ERR_OK if successful, ERR_VAL if we can't decode
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| 354 | */
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| 355 | err_t
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| 356 | snmp_asn1_dec_tlv(struct snmp_pbuf_stream *pbuf_stream, struct snmp_asn1_tlv *tlv)
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| 357 | {
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| 358 | u8_t data;
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| 359 |
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| 360 | /* decode type first */
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| 361 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
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| 362 | tlv->type = data;
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| 363 |
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| 364 | if ((tlv->type & SNMP_ASN1_DATATYPE_MASK) == SNMP_ASN1_DATATYPE_EXTENDED) {
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| 365 | /* extended format is not used by SNMP so we do not accept those values */
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| 366 | return ERR_VAL;
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| 367 | }
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| 368 | tlv->type_len = 1;
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| 369 |
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| 370 | /* now, decode length */
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| 371 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
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| 372 |
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| 373 | if (data < 0x80) { /* short form */
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| 374 | tlv->length_len = 1;
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| 375 | tlv->value_len = data;
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| 376 | } else if (data > 0x80) { /* long form */
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| 377 | u8_t length_bytes = data - 0x80;
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| 378 | if (length_bytes > pbuf_stream->length) {
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| 379 | return ERR_VAL;
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| 380 | }
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| 381 | tlv->length_len = length_bytes + 1; /* this byte + defined number of length bytes following */
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| 382 | tlv->value_len = 0;
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| 383 |
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| 384 | while (length_bytes > 0) {
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| 385 | /* we only support up to u16.maxvalue-1 (2 bytes) but have to accept leading zero bytes */
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| 386 | if (tlv->value_len > 0xFF) {
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| 387 | return ERR_VAL;
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| 388 | }
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| 389 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
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| 390 | tlv->value_len <<= 8;
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| 391 | tlv->value_len |= data;
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| 392 |
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| 393 | /* take care for special value used for indefinite length */
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| 394 | if (tlv->value_len == 0xFFFF) {
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| 395 | return ERR_VAL;
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| 396 | }
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| 397 |
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| 398 | length_bytes--;
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| 399 | }
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| 400 | } else { /* data == 0x80 indefinite length form */
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| 401 | /* (not allowed for SNMP; RFC 1157, 3.2.2) */
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| 402 | return ERR_VAL;
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| 403 | }
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| 404 |
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| 405 | return ERR_OK;
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| 406 | }
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| 407 |
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| 408 | /**
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| 409 | * Decodes positive integer (counter, gauge, timeticks) into u32_t.
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| 410 | *
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| 411 | * @param pbuf_stream points to a pbuf stream
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| 412 | * @param len length of the coded integer field
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| 413 | * @param value return host order integer
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| 414 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
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| 415 | *
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| 416 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
|
---|
| 417 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
|
---|
| 418 | * of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
|
---|
| 419 | */
|
---|
| 420 | err_t
|
---|
| 421 | snmp_asn1_dec_u32t(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u32_t *value)
|
---|
| 422 | {
|
---|
| 423 | u8_t data;
|
---|
| 424 |
|
---|
| 425 | if ((len > 0) && (len <= 5)) {
|
---|
| 426 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 427 |
|
---|
| 428 | /* expecting sign bit to be zero, only unsigned please! */
|
---|
| 429 | if (((len == 5) && (data == 0x00)) || ((len < 5) && ((data & 0x80) == 0))) {
|
---|
| 430 | *value = data;
|
---|
| 431 | len--;
|
---|
| 432 |
|
---|
| 433 | while (len > 0) {
|
---|
| 434 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 435 | len--;
|
---|
| 436 |
|
---|
| 437 | *value <<= 8;
|
---|
| 438 | *value |= data;
|
---|
| 439 | }
|
---|
| 440 |
|
---|
| 441 | return ERR_OK;
|
---|
| 442 | }
|
---|
| 443 | }
|
---|
| 444 |
|
---|
| 445 | return ERR_VAL;
|
---|
| 446 | }
|
---|
| 447 |
|
---|
| 448 | /**
|
---|
| 449 | * Decodes integer into s32_t.
|
---|
| 450 | *
|
---|
| 451 | * @param pbuf_stream points to a pbuf stream
|
---|
| 452 | * @param len length of the coded integer field
|
---|
| 453 | * @param value return host order integer
|
---|
| 454 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
| 455 | *
|
---|
| 456 | * @note ASN coded integers are _always_ signed!
|
---|
| 457 | */
|
---|
| 458 | err_t
|
---|
| 459 | snmp_asn1_dec_s32t(struct snmp_pbuf_stream *pbuf_stream, u16_t len, s32_t *value)
|
---|
| 460 | {
|
---|
| 461 | u8_t data;
|
---|
| 462 |
|
---|
| 463 | if ((len > 0) && (len < 5)) {
|
---|
| 464 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 465 |
|
---|
| 466 | if (data & 0x80) {
|
---|
| 467 | /* negative, start from -1 */
|
---|
| 468 | *value = -1;
|
---|
| 469 | *value = (*value << 8) | data;
|
---|
| 470 | } else {
|
---|
| 471 | /* positive, start from 0 */
|
---|
| 472 | *value = data;
|
---|
| 473 | }
|
---|
| 474 | len--;
|
---|
| 475 | /* shift in the remaining value */
|
---|
| 476 | while (len > 0) {
|
---|
| 477 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 478 | *value = (*value << 8) | data;
|
---|
| 479 | len--;
|
---|
| 480 | }
|
---|
| 481 | return ERR_OK;
|
---|
| 482 | }
|
---|
| 483 |
|
---|
| 484 | return ERR_VAL;
|
---|
| 485 | }
|
---|
| 486 |
|
---|
| 487 | /**
|
---|
| 488 | * Decodes object identifier from incoming message into array of u32_t.
|
---|
| 489 | *
|
---|
| 490 | * @param pbuf_stream points to a pbuf stream
|
---|
| 491 | * @param len length of the coded object identifier
|
---|
| 492 | * @param oid return decoded object identifier
|
---|
| 493 | * @param oid_len return decoded object identifier length
|
---|
| 494 | * @param oid_max_len size of oid buffer
|
---|
| 495 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
| 496 | */
|
---|
| 497 | err_t
|
---|
| 498 | snmp_asn1_dec_oid(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u32_t *oid, u8_t *oid_len, u8_t oid_max_len)
|
---|
| 499 | {
|
---|
| 500 | u32_t *oid_ptr;
|
---|
| 501 | u8_t data;
|
---|
| 502 |
|
---|
| 503 | *oid_len = 0;
|
---|
| 504 | oid_ptr = oid;
|
---|
| 505 | if (len > 0) {
|
---|
| 506 | if (oid_max_len < 2) {
|
---|
| 507 | return ERR_MEM;
|
---|
| 508 | }
|
---|
| 509 |
|
---|
| 510 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 511 | len--;
|
---|
| 512 |
|
---|
| 513 | /* first compressed octet */
|
---|
| 514 | if (data == 0x2B) {
|
---|
| 515 | /* (most) common case 1.3 (iso.org) */
|
---|
| 516 | *oid_ptr = 1;
|
---|
| 517 | oid_ptr++;
|
---|
| 518 | *oid_ptr = 3;
|
---|
| 519 | oid_ptr++;
|
---|
| 520 | } else if (data < 40) {
|
---|
| 521 | *oid_ptr = 0;
|
---|
| 522 | oid_ptr++;
|
---|
| 523 | *oid_ptr = data;
|
---|
| 524 | oid_ptr++;
|
---|
| 525 | } else if (data < 80) {
|
---|
| 526 | *oid_ptr = 1;
|
---|
| 527 | oid_ptr++;
|
---|
| 528 | *oid_ptr = data - 40;
|
---|
| 529 | oid_ptr++;
|
---|
| 530 | } else {
|
---|
| 531 | *oid_ptr = 2;
|
---|
| 532 | oid_ptr++;
|
---|
| 533 | *oid_ptr = data - 80;
|
---|
| 534 | oid_ptr++;
|
---|
| 535 | }
|
---|
| 536 | *oid_len = 2;
|
---|
| 537 | } else {
|
---|
| 538 | /* accepting zero length identifiers e.g. for getnext operation. uncommon but valid */
|
---|
| 539 | return ERR_OK;
|
---|
| 540 | }
|
---|
| 541 |
|
---|
| 542 | while ((len > 0) && (*oid_len < oid_max_len)) {
|
---|
| 543 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 544 | len--;
|
---|
| 545 |
|
---|
| 546 | if ((data & 0x80) == 0x00) {
|
---|
| 547 | /* sub-identifier uses single octet */
|
---|
| 548 | *oid_ptr = data;
|
---|
| 549 | } else {
|
---|
| 550 | /* sub-identifier uses multiple octets */
|
---|
| 551 | u32_t sub_id = (data & ~0x80);
|
---|
| 552 | while ((len > 0) && ((data & 0x80) != 0)) {
|
---|
| 553 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 554 | len--;
|
---|
| 555 |
|
---|
| 556 | sub_id = (sub_id << 7) + (data & ~0x80);
|
---|
| 557 | }
|
---|
| 558 |
|
---|
| 559 | if ((data & 0x80) != 0) {
|
---|
| 560 | /* "more bytes following" bit still set at end of len */
|
---|
| 561 | return ERR_VAL;
|
---|
| 562 | }
|
---|
| 563 | *oid_ptr = sub_id;
|
---|
| 564 | }
|
---|
| 565 | oid_ptr++;
|
---|
| 566 | (*oid_len)++;
|
---|
| 567 | }
|
---|
| 568 |
|
---|
| 569 | if (len > 0) {
|
---|
| 570 | /* OID to long to fit in our buffer */
|
---|
| 571 | return ERR_MEM;
|
---|
| 572 | }
|
---|
| 573 |
|
---|
| 574 | return ERR_OK;
|
---|
| 575 | }
|
---|
| 576 |
|
---|
| 577 | /**
|
---|
| 578 | * Decodes (copies) raw data (ip-addresses, octet strings, opaque encoding)
|
---|
| 579 | * from incoming message into array.
|
---|
| 580 | *
|
---|
| 581 | * @param pbuf_stream points to a pbuf stream
|
---|
| 582 | * @param len length of the coded raw data (zero is valid, e.g. empty string!)
|
---|
| 583 | * @param buf return raw bytes
|
---|
| 584 | * @param buf_len returns length of the raw return value
|
---|
| 585 | * @param buf_max_len buffer size
|
---|
| 586 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
| 587 | */
|
---|
| 588 | err_t
|
---|
| 589 | snmp_asn1_dec_raw(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u8_t *buf, u16_t *buf_len, u16_t buf_max_len)
|
---|
| 590 | {
|
---|
| 591 | if (len > buf_max_len) {
|
---|
| 592 | /* not enough dst space */
|
---|
| 593 | return ERR_MEM;
|
---|
| 594 | }
|
---|
| 595 | *buf_len = len;
|
---|
| 596 |
|
---|
| 597 | while (len > 0) {
|
---|
| 598 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, buf));
|
---|
| 599 | buf++;
|
---|
| 600 | len--;
|
---|
| 601 | }
|
---|
| 602 |
|
---|
| 603 | return ERR_OK;
|
---|
| 604 | }
|
---|
| 605 |
|
---|
| 606 | #if LWIP_HAVE_INT64
|
---|
| 607 | /**
|
---|
| 608 | * Returns octet count for an u64_t.
|
---|
| 609 | *
|
---|
| 610 | * @param value value to be encoded
|
---|
| 611 | * @param octets_needed points to the return value
|
---|
| 612 | *
|
---|
| 613 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
|
---|
| 614 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
|
---|
| 615 | * of 0xFFFFFFFFFFFFFFFF is preceded with 0x00 and the length is 9 octets!!
|
---|
| 616 | */
|
---|
| 617 | void
|
---|
| 618 | snmp_asn1_enc_u64t_cnt(u64_t value, u16_t *octets_needed)
|
---|
| 619 | {
|
---|
| 620 | /* check if high u32 is 0 */
|
---|
| 621 | if ((value >> 32) == 0) {
|
---|
| 622 | /* only low u32 is important */
|
---|
| 623 | snmp_asn1_enc_u32t_cnt((u32_t)value, octets_needed);
|
---|
| 624 | } else {
|
---|
| 625 | /* low u32 does not matter for length determination */
|
---|
| 626 | snmp_asn1_enc_u32t_cnt((u32_t)(value >> 32), octets_needed);
|
---|
| 627 | *octets_needed = *octets_needed + 4; /* add the 4 bytes of low u32 */
|
---|
| 628 | }
|
---|
| 629 | }
|
---|
| 630 |
|
---|
| 631 | /**
|
---|
| 632 | * Decodes large positive integer (counter64) into 2x u32_t.
|
---|
| 633 | *
|
---|
| 634 | * @param pbuf_stream points to a pbuf stream
|
---|
| 635 | * @param len length of the coded integer field
|
---|
| 636 | * @param value return 64 bit integer
|
---|
| 637 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
| 638 | *
|
---|
| 639 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
|
---|
| 640 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
|
---|
| 641 | * of 0xFFFFFFFFFFFFFFFF is preceded with 0x00 and the length is 9 octets!!
|
---|
| 642 | */
|
---|
| 643 | err_t
|
---|
| 644 | snmp_asn1_dec_u64t(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u64_t *value)
|
---|
| 645 | {
|
---|
| 646 | u8_t data;
|
---|
| 647 |
|
---|
| 648 | if ((len > 0) && (len <= 9)) {
|
---|
| 649 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 650 |
|
---|
| 651 | /* expecting sign bit to be zero, only unsigned please! */
|
---|
| 652 | if (((len == 9) && (data == 0x00)) || ((len < 9) && ((data & 0x80) == 0))) {
|
---|
| 653 | *value = data;
|
---|
| 654 | len--;
|
---|
| 655 |
|
---|
| 656 | while (len > 0) {
|
---|
| 657 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
| 658 | *value <<= 8;
|
---|
| 659 | *value |= data;
|
---|
| 660 | len--;
|
---|
| 661 | }
|
---|
| 662 |
|
---|
| 663 | return ERR_OK;
|
---|
| 664 | }
|
---|
| 665 | }
|
---|
| 666 |
|
---|
| 667 | return ERR_VAL;
|
---|
| 668 | }
|
---|
| 669 |
|
---|
| 670 | /**
|
---|
| 671 | * Encodes u64_t (counter64) into a pbuf chained ASN1 msg.
|
---|
| 672 | *
|
---|
| 673 | * @param pbuf_stream points to a pbuf stream
|
---|
| 674 | * @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
|
---|
| 675 | * @param value is the value to be encoded
|
---|
| 676 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
|
---|
| 677 | *
|
---|
| 678 | * @see snmp_asn1_enc_u64t_cnt()
|
---|
| 679 | */
|
---|
| 680 | err_t
|
---|
| 681 | snmp_asn1_enc_u64t(struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, u64_t value)
|
---|
| 682 | {
|
---|
| 683 | if (octets_needed > 9) {
|
---|
| 684 | return ERR_ARG;
|
---|
| 685 | }
|
---|
| 686 | if (octets_needed == 9) {
|
---|
| 687 | /* not enough bits in 'value' add leading 0x00 */
|
---|
| 688 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, 0x00));
|
---|
| 689 | octets_needed--;
|
---|
| 690 | }
|
---|
| 691 |
|
---|
| 692 | while (octets_needed > 1) {
|
---|
| 693 | octets_needed--;
|
---|
| 694 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value >> (octets_needed << 3))));
|
---|
| 695 | }
|
---|
| 696 |
|
---|
| 697 | /* always write at least one octet (also in case of value == 0) */
|
---|
| 698 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value)));
|
---|
| 699 |
|
---|
| 700 | return ERR_OK;
|
---|
| 701 | }
|
---|
| 702 | #endif
|
---|
| 703 |
|
---|
| 704 | #endif /* LWIP_SNMP */
|
---|