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]);
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464 | }
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465 | ofs += 1;
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466 | if (ofs >= plen)
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467 | {
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468 | /* next octet in next pbuf */
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469 | p = p->next;
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470 | if (p == NULL) { return ERR_ARG; }
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471 | msg_ptr = (u8_t*)p->payload;
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472 | plen += p->len;
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473 | }
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474 | else
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475 | {
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476 | /* next octet in same pbuf */
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477 | msg_ptr++;
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478 | }
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479 | ident_len -= 2;
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480 | ident += 2;
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481 | }
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482 | else
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483 | {
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484 | /* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */
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485 | /* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */
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486 | return ERR_ARG;
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487 | }
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488 | while (ident_len > 0)
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489 | {
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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 */
|
---|