[164] | 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 | */
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| 36 |
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| 37 | #include "lwip/opt.h"
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| 38 |
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| 39 | #if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
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| 40 |
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| 41 | #include "lwip/snmp_asn1.h"
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| 42 |
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| 43 | /**
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| 44 | * Returns octet count for length.
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| 45 | *
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| 46 | * @param length
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| 47 | * @param octets_needed points to the return value
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| 48 | */
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| 49 | void
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| 50 | snmp_asn1_enc_length_cnt(u16_t length, u8_t *octets_needed)
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| 51 | {
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| 52 | if (length < 0x80U)
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| 53 | {
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| 54 | *octets_needed = 1;
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| 55 | }
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| 56 | else if (length < 0x100U)
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| 57 | {
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| 58 | *octets_needed = 2;
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| 59 | }
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| 60 | else
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| 61 | {
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| 62 | *octets_needed = 3;
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| 63 | }
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| 64 | }
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| 65 |
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| 66 | /**
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| 67 | * Returns octet count for an u32_t.
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| 68 | *
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| 69 | * @param value
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| 70 | * @param octets_needed points to the return value
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| 71 | *
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| 72 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
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| 73 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
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| 74 | * of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
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| 75 | */
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| 76 | void
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| 77 | snmp_asn1_enc_u32t_cnt(u32_t value, u16_t *octets_needed)
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| 78 | {
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| 79 | if (value < 0x80UL)
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| 80 | {
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| 81 | *octets_needed = 1;
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| 82 | }
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| 83 | else if (value < 0x8000UL)
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| 84 | {
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| 85 | *octets_needed = 2;
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| 86 | }
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| 87 | else if (value < 0x800000UL)
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| 88 | {
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| 89 | *octets_needed = 3;
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| 90 | }
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| 91 | else if (value < 0x80000000UL)
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| 92 | {
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| 93 | *octets_needed = 4;
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| 94 | }
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| 95 | else
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| 96 | {
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| 97 | *octets_needed = 5;
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| 98 | }
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| 99 | }
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| 100 |
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| 101 | /**
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| 102 | * Returns octet count for an s32_t.
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| 103 | *
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| 104 | * @param value
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| 105 | * @param octets_needed points to the return value
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| 106 | *
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| 107 | * @note ASN coded integers are _always_ signed.
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| 108 | */
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| 109 | void
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| 110 | snmp_asn1_enc_s32t_cnt(s32_t value, u16_t *octets_needed)
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| 111 | {
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| 112 | if (value < 0)
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| 113 | {
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| 114 | value = ~value;
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| 115 | }
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| 116 | if (value < 0x80L)
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| 117 | {
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| 118 | *octets_needed = 1;
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| 119 | }
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| 120 | else if (value < 0x8000L)
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| 121 | {
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| 122 | *octets_needed = 2;
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| 123 | }
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| 124 | else if (value < 0x800000L)
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| 125 | {
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| 126 | *octets_needed = 3;
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| 127 | }
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| 128 | else
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| 129 | {
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| 130 | *octets_needed = 4;
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| 131 | }
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| 132 | }
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| 133 |
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| 134 | /**
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| 135 | * Returns octet count for an object identifier.
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| 136 | *
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| 137 | * @param ident_len object identifier array length
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| 138 | * @param ident points to object identifier array
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| 139 | * @param octets_needed points to the return value
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| 140 | */
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| 141 | void
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| 142 | snmp_asn1_enc_oid_cnt(u8_t ident_len, s32_t *ident, u16_t *octets_needed)
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| 143 | {
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| 144 | s32_t sub_id;
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| 145 | u8_t cnt;
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| 146 |
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| 147 | cnt = 0;
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| 148 | if (ident_len > 1)
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| 149 | {
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| 150 | /* compressed prefix in one octet */
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| 151 | cnt++;
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| 152 | ident_len -= 2;
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| 153 | ident += 2;
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| 154 | }
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| 155 | while(ident_len > 0)
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| 156 | {
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| 157 | ident_len--;
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| 158 | sub_id = *ident;
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| 159 |
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| 160 | sub_id >>= 7;
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| 161 | cnt++;
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| 162 | while(sub_id > 0)
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| 163 | {
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| 164 | sub_id >>= 7;
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| 165 | cnt++;
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| 166 | }
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| 167 | ident++;
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| 168 | }
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| 169 | *octets_needed = cnt;
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| 170 | }
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| 171 |
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| 172 | /**
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| 173 | * Encodes ASN type field into a pbuf chained ASN1 msg.
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| 174 | *
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| 175 | * @param p points to output pbuf to encode value into
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| 176 | * @param ofs points to the offset within the pbuf chain
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| 177 | * @param type input ASN1 type
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| 178 | * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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| 179 | */
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| 180 | err_t
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| 181 | snmp_asn1_enc_type(struct pbuf *p, u16_t ofs, u8_t type)
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| 182 | {
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| 183 | u16_t plen, base;
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| 184 | u8_t *msg_ptr;
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| 185 |
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| 186 | plen = 0;
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| 187 | while (p != NULL)
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| 188 | {
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| 189 | base = plen;
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| 190 | plen += p->len;
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| 191 | if (ofs < plen)
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| 192 | {
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| 193 | msg_ptr = (u8_t*)p->payload;
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| 194 | msg_ptr += ofs - base;
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| 195 | *msg_ptr = type;
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| 196 | return ERR_OK;
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| 197 | }
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| 198 | p = p->next;
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| 199 | }
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| 200 | /* p == NULL, ofs >= plen */
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| 201 | return ERR_ARG;
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| 202 | }
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| 203 |
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| 204 | /**
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| 205 | * Encodes host order length field into a pbuf chained ASN1 msg.
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| 206 | *
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| 207 | * @param p points to output pbuf to encode length into
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| 208 | * @param ofs points to the offset within the pbuf chain
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| 209 | * @param length is the host order length to be encoded
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| 210 | * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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| 211 | */
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| 212 | err_t
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| 213 | snmp_asn1_enc_length(struct pbuf *p, u16_t ofs, u16_t length)
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| 214 | {
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| 215 | u16_t plen, base;
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| 216 | u8_t *msg_ptr;
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| 217 |
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| 218 | plen = 0;
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| 219 | while (p != NULL)
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| 220 | {
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| 221 | base = plen;
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| 222 | plen += p->len;
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| 223 | if (ofs < plen)
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| 224 | {
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| 225 | msg_ptr = (u8_t*)p->payload;
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| 226 | msg_ptr += ofs - base;
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| 227 |
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| 228 | if (length < 0x80)
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| 229 | {
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| 230 | *msg_ptr = (u8_t)length;
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| 231 | return ERR_OK;
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| 232 | }
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| 233 | else if (length < 0x100)
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| 234 | {
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| 235 | *msg_ptr = 0x81;
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| 236 | ofs += 1;
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| 237 | if (ofs >= plen)
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| 238 | {
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| 239 | /* next octet in next pbuf */
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| 240 | p = p->next;
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| 241 | if (p == NULL) { return ERR_ARG; }
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| 242 | msg_ptr = (u8_t*)p->payload;
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| 243 | }
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| 244 | else
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| 245 | {
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| 246 | /* next octet in same pbuf */
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| 247 | msg_ptr++;
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| 248 | }
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| 249 | *msg_ptr = (u8_t)length;
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| 250 | return ERR_OK;
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| 251 | }
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| 252 | else
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| 253 | {
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| 254 | u8_t i;
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| 255 |
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| 256 | /* length >= 0x100 && length <= 0xFFFF */
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| 257 | *msg_ptr = 0x82;
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| 258 | i = 2;
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| 259 | while (i > 0)
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| 260 | {
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| 261 | i--;
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| 262 | ofs += 1;
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| 263 | if (ofs >= plen)
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| 264 | {
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| 265 | /* next octet in next pbuf */
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| 266 | p = p->next;
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| 267 | if (p == NULL) { return ERR_ARG; }
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| 268 | msg_ptr = (u8_t*)p->payload;
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| 269 | plen += p->len;
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| 270 | }
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| 271 | else
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| 272 | {
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| 273 | /* next octet in same pbuf */
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| 274 | msg_ptr++;
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| 275 | }
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| 276 | if (i == 0)
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| 277 | {
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| 278 | /* least significant length octet */
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| 279 | *msg_ptr = (u8_t)length;
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| 280 | }
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| 281 | else
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| 282 | {
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| 283 | /* most significant length octet */
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| 284 | *msg_ptr = (u8_t)(length >> 8);
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| 285 | }
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| 286 | }
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| 287 | return ERR_OK;
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| 288 | }
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| 289 | }
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| 290 | p = p->next;
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| 291 | }
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| 292 | /* p == NULL, ofs >= plen */
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| 293 | return ERR_ARG;
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| 294 | }
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| 295 |
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| 296 | /**
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| 297 | * Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg.
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| 298 | *
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| 299 | * @param p points to output pbuf to encode value into
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| 300 | * @param ofs points to the offset within the pbuf chain
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| 301 | * @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
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| 302 | * @param value is the host order u32_t value to be encoded
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| 303 | * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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| 304 | *
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| 305 | * @see snmp_asn1_enc_u32t_cnt()
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| 306 | */
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| 307 | err_t
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| 308 | snmp_asn1_enc_u32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, u32_t value)
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| 309 | {
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| 310 | u16_t plen, base;
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| 311 | u8_t *msg_ptr;
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| 312 |
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| 313 | plen = 0;
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| 314 | while (p != NULL)
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| 315 | {
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| 316 | base = plen;
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| 317 | plen += p->len;
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| 318 | if (ofs < plen)
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| 319 | {
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| 320 | msg_ptr = (u8_t*)p->payload;
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| 321 | msg_ptr += ofs - base;
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| 322 |
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| 323 | if (octets_needed == 5)
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| 324 | {
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| 325 | /* not enough bits in 'value' add leading 0x00 */
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| 326 | octets_needed--;
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| 327 | *msg_ptr = 0x00;
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| 328 | ofs += 1;
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| 329 | if (ofs >= plen)
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| 330 | {
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| 331 | /* next octet in next pbuf */
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| 332 | p = p->next;
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| 333 | if (p == NULL) { return ERR_ARG; }
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| 334 | msg_ptr = (u8_t*)p->payload;
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| 335 | plen += p->len;
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| 336 | }
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| 337 | else
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| 338 | {
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| 339 | /* next octet in same pbuf */
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| 340 | msg_ptr++;
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| 341 | }
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| 342 | }
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| 343 | while (octets_needed > 1)
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| 344 | {
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| 345 | octets_needed--;
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| 346 | *msg_ptr = (u8_t)(value >> (octets_needed << 3));
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| 347 | ofs += 1;
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| 348 | if (ofs >= plen)
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| 349 | {
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| 350 | /* next octet in next pbuf */
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| 351 | p = p->next;
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| 352 | if (p == NULL) { return ERR_ARG; }
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| 353 | msg_ptr = (u8_t*)p->payload;
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| 354 | plen += p->len;
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| 355 | }
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| 356 | else
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| 357 | {
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| 358 | /* next octet in same pbuf */
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| 359 | msg_ptr++;
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| 360 | }
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| 361 | }
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| 362 | /* (only) one least significant octet */
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| 363 | *msg_ptr = (u8_t)value;
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| 364 | return ERR_OK;
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| 365 | }
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| 366 | p = p->next;
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| 367 | }
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| 368 | /* p == NULL, ofs >= plen */
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| 369 | return ERR_ARG;
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| 370 | }
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| 371 |
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| 372 | /**
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| 373 | * Encodes s32_t integer into a pbuf chained ASN1 msg.
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| 374 | *
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| 375 | * @param p points to output pbuf to encode value into
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| 376 | * @param ofs points to the offset within the pbuf chain
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| 377 | * @param octets_needed encoding length (from snmp_asn1_enc_s32t_cnt())
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| 378 | * @param value is the host order s32_t value to be encoded
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| 379 | * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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| 380 | *
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| 381 | * @see snmp_asn1_enc_s32t_cnt()
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| 382 | */
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| 383 | err_t
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| 384 | snmp_asn1_enc_s32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, s32_t value)
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| 385 | {
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| 386 | u16_t plen, base;
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| 387 | u8_t *msg_ptr;
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| 388 |
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| 389 | plen = 0;
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| 390 | while (p != NULL)
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| 391 | {
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| 392 | base = plen;
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| 393 | plen += p->len;
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| 394 | if (ofs < plen)
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| 395 | {
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| 396 | msg_ptr = (u8_t*)p->payload;
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| 397 | msg_ptr += ofs - base;
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| 398 |
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| 399 | while (octets_needed > 1)
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| 400 | {
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| 401 | octets_needed--;
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| 402 | *msg_ptr = (u8_t)(value >> (octets_needed << 3));
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| 403 | ofs += 1;
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| 404 | if (ofs >= plen)
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| 405 | {
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| 406 | /* next octet in next pbuf */
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| 407 | p = p->next;
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| 408 | if (p == NULL) { return ERR_ARG; }
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| 409 | msg_ptr = (u8_t*)p->payload;
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| 410 | plen += p->len;
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| 411 | }
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| 412 | else
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| 413 | {
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| 414 | /* next octet in same pbuf */
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| 415 | msg_ptr++;
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| 416 | }
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| 417 | }
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| 418 | /* (only) one least significant octet */
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| 419 | *msg_ptr = (u8_t)value;
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| 420 | return ERR_OK;
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| 421 | }
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| 422 | p = p->next;
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| 423 | }
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| 424 | /* p == NULL, ofs >= plen */
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| 425 | return ERR_ARG;
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| 426 | }
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| 427 |
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| 428 | /**
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| 429 | * Encodes object identifier into a pbuf chained ASN1 msg.
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| 430 | *
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| 431 | * @param p points to output pbuf to encode oid into
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| 432 | * @param ofs points to the offset within the pbuf chain
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| 433 | * @param ident_len object identifier array length
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| 434 | * @param ident points to object identifier array
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| 435 | * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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| 436 | */
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| 437 | err_t
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| 438 | snmp_asn1_enc_oid(struct pbuf *p, u16_t ofs, u8_t ident_len, s32_t *ident)
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| 439 | {
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| 440 | u16_t plen, base;
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| 441 | u8_t *msg_ptr;
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| 442 |
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| 443 | plen = 0;
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| 444 | while (p != NULL)
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| 445 | {
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| 446 | base = plen;
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| 447 | plen += p->len;
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| 448 | if (ofs < plen)
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| 449 | {
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| 450 | msg_ptr = (u8_t*)p->payload;
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| 451 | msg_ptr += ofs - base;
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| 452 |
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| 453 | if (ident_len > 1)
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| 454 | {
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| 455 | if ((ident[0] == 1) && (ident[1] == 3))
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| 456 | {
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| 457 | /* compressed (most common) prefix .iso.org */
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| 458 | *msg_ptr = 0x2b;
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| 459 | }
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| 460 | else
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| 461 | {
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| 462 | /* calculate prefix */
|
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| 463 | *msg_ptr = (u8_t)((ident[0] * 40) + ident[1]);
|
---|
| 464 | }
|
---|
| 465 | ofs += 1;
|
---|
| 466 | if (ofs >= plen)
|
---|
| 467 | {
|
---|
| 468 | /* next octet in next pbuf */
|
---|
| 469 | p = p->next;
|
---|
| 470 | if (p == NULL) { return ERR_ARG; }
|
---|
| 471 | msg_ptr = (u8_t*)p->payload;
|
---|
| 472 | plen += p->len;
|
---|
| 473 | }
|
---|
| 474 | else
|
---|
| 475 | {
|
---|
| 476 | /* next octet in same pbuf */
|
---|
| 477 | msg_ptr++;
|
---|
| 478 | }
|
---|
| 479 | ident_len -= 2;
|
---|
| 480 | ident += 2;
|
---|
| 481 | }
|
---|
| 482 | else
|
---|
| 483 | {
|
---|
| 484 | /* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */
|
---|
| 485 | /* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */
|
---|
| 486 | return ERR_ARG;
|
---|
| 487 | }
|
---|
| 488 | while (ident_len > 0)
|
---|
| 489 | {
|
---|
| 490 | s32_t sub_id;
|
---|
| 491 | u8_t shift, tail;
|
---|
| 492 |
|
---|
| 493 | ident_len--;
|
---|
| 494 | sub_id = *ident;
|
---|
| 495 | tail = 0;
|
---|
| 496 | shift = 28;
|
---|
| 497 | while(shift > 0)
|
---|
| 498 | {
|
---|
| 499 | u8_t code;
|
---|
| 500 |
|
---|
| 501 | code = (u8_t)(sub_id >> shift);
|
---|
| 502 | if ((code != 0) || (tail != 0))
|
---|
| 503 | {
|
---|
| 504 | tail = 1;
|
---|
| 505 | *msg_ptr = code | 0x80;
|
---|
| 506 | ofs += 1;
|
---|
| 507 | if (ofs >= plen)
|
---|
| 508 | {
|
---|
| 509 | /* next octet in next pbuf */
|
---|
| 510 | p = p->next;
|
---|
| 511 | if (p == NULL) { return ERR_ARG; }
|
---|
| 512 | msg_ptr = (u8_t*)p->payload;
|
---|
| 513 | plen += p->len;
|
---|
| 514 | }
|
---|
| 515 | else
|
---|
| 516 | {
|
---|
| 517 | /* next octet in same pbuf */
|
---|
| 518 | msg_ptr++;
|
---|
| 519 | }
|
---|
| 520 | }
|
---|
| 521 | shift -= 7;
|
---|
| 522 | }
|
---|
| 523 | *msg_ptr = (u8_t)sub_id & 0x7F;
|
---|
| 524 | if (ident_len > 0)
|
---|
| 525 | {
|
---|
| 526 | ofs += 1;
|
---|
| 527 | if (ofs >= plen)
|
---|
| 528 | {
|
---|
| 529 | /* next octet in next pbuf */
|
---|
| 530 | p = p->next;
|
---|
| 531 | if (p == NULL) { return ERR_ARG; }
|
---|
| 532 | msg_ptr = (u8_t*)p->payload;
|
---|
| 533 | plen += p->len;
|
---|
| 534 | }
|
---|
| 535 | else
|
---|
| 536 | {
|
---|
| 537 | /* next octet in same pbuf */
|
---|
| 538 | msg_ptr++;
|
---|
| 539 | }
|
---|
| 540 | }
|
---|
| 541 | /* proceed to next sub-identifier */
|
---|
| 542 | ident++;
|
---|
| 543 | }
|
---|
| 544 | return ERR_OK;
|
---|
| 545 | }
|
---|
| 546 | p = p->next;
|
---|
| 547 | }
|
---|
| 548 | /* p == NULL, ofs >= plen */
|
---|
| 549 | return ERR_ARG;
|
---|
| 550 | }
|
---|
| 551 |
|
---|
| 552 | /**
|
---|
| 553 | * Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg.
|
---|
| 554 | *
|
---|
| 555 | * @param p points to output pbuf to encode raw data into
|
---|
| 556 | * @param ofs points to the offset within the pbuf chain
|
---|
| 557 | * @param raw_len raw data length
|
---|
| 558 | * @param raw points raw data
|
---|
| 559 | * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
|
---|
| 560 | */
|
---|
| 561 | err_t
|
---|
| 562 | snmp_asn1_enc_raw(struct pbuf *p, u16_t ofs, u16_t raw_len, u8_t *raw)
|
---|
| 563 | {
|
---|
| 564 | u16_t plen, base;
|
---|
| 565 | u8_t *msg_ptr;
|
---|
| 566 |
|
---|
| 567 | plen = 0;
|
---|
| 568 | while (p != NULL)
|
---|
| 569 | {
|
---|
| 570 | base = plen;
|
---|
| 571 | plen += p->len;
|
---|
| 572 | if (ofs < plen)
|
---|
| 573 | {
|
---|
| 574 | msg_ptr = (u8_t*)p->payload;
|
---|
| 575 | msg_ptr += ofs - base;
|
---|
| 576 |
|
---|
| 577 | while (raw_len > 1)
|
---|
| 578 | {
|
---|
| 579 | /* copy raw_len - 1 octets */
|
---|
| 580 | raw_len--;
|
---|
| 581 | *msg_ptr = *raw;
|
---|
| 582 | raw++;
|
---|
| 583 | ofs += 1;
|
---|
| 584 | if (ofs >= plen)
|
---|
| 585 | {
|
---|
| 586 | /* next octet in next pbuf */
|
---|
| 587 | p = p->next;
|
---|
| 588 | if (p == NULL) { return ERR_ARG; }
|
---|
| 589 | msg_ptr = (u8_t*)p->payload;
|
---|
| 590 | plen += p->len;
|
---|
| 591 | }
|
---|
| 592 | else
|
---|
| 593 | {
|
---|
| 594 | /* next octet in same pbuf */
|
---|
| 595 | msg_ptr++;
|
---|
| 596 | }
|
---|
| 597 | }
|
---|
| 598 | if (raw_len > 0)
|
---|
| 599 | {
|
---|
| 600 | /* copy last or single octet */
|
---|
| 601 | *msg_ptr = *raw;
|
---|
| 602 | }
|
---|
| 603 | return ERR_OK;
|
---|
| 604 | }
|
---|
| 605 | p = p->next;
|
---|
| 606 | }
|
---|
| 607 | /* p == NULL, ofs >= plen */
|
---|
| 608 | return ERR_ARG;
|
---|
| 609 | }
|
---|
| 610 |
|
---|
| 611 | #endif /* LWIP_SNMP */
|
---|