1 | /**
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2 | * @file
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3 | * Functions common to all TCP/IPv6 modules, such as the Internet checksum and the
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4 | * byte order functions.
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5 | *
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6 | */
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7 |
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8 | /*
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9 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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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 | * This file is part of the lwIP TCP/IP stack.
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35 | *
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36 | * Author: Adam Dunkels <adam@sics.se>
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37 | *
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38 | */
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39 |
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40 | #include "lwip/opt.h"
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41 |
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42 | #include "lwip/def.h"
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43 | #include "lwip/inet.h"
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44 |
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45 | /* chksum:
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46 | *
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47 | * Sums up all 16 bit words in a memory portion. Also includes any odd byte.
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48 | * This function is used by the other checksum functions.
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49 | *
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50 | * For now, this is not optimized. Must be optimized for the particular processor
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51 | * arcitecture on which it is to run. Preferebly coded in assembler.
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52 | */
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53 |
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54 | static u32_t
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55 | chksum(void *dataptr, u16_t len)
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56 | {
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57 | u16_t *sdataptr = dataptr;
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58 | u32_t acc;
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59 |
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60 |
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61 | for(acc = 0; len > 1; len -= 2) {
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62 | acc += *sdataptr++;
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63 | }
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64 |
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65 | /* add up any odd byte */
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66 | if (len == 1) {
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67 | acc += htons((u16_t)(*(u8_t *)dataptr) << 8);
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68 | }
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69 |
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70 | return acc;
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71 |
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72 | }
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73 |
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74 | /* inet_chksum_pseudo:
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75 | *
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76 | * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
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77 | */
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78 |
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79 | u16_t
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80 | inet_chksum_pseudo(struct pbuf *p,
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81 | struct ip_addr *src, struct ip_addr *dest,
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82 | u8_t proto, u32_t proto_len)
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83 | {
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84 | u32_t acc;
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85 | struct pbuf *q;
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86 | u8_t swapped, i;
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87 |
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88 | acc = 0;
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89 | swapped = 0;
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90 | for(q = p; q != NULL; q = q->next) {
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91 | acc += chksum(q->payload, q->len);
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92 | while (acc >> 16) {
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93 | acc = (acc & 0xffff) + (acc >> 16);
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94 | }
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95 | if (q->len % 2 != 0) {
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96 | swapped = 1 - swapped;
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97 | acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
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98 | }
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99 | }
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100 |
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101 | if (swapped) {
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102 | acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
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103 | }
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104 |
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105 | for(i = 0; i < 8; i++) {
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106 | acc += ((u16_t *)src->addr)[i] & 0xffff;
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107 | acc += ((u16_t *)dest->addr)[i] & 0xffff;
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108 | while (acc >> 16) {
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109 | acc = (acc & 0xffff) + (acc >> 16);
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110 | }
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111 | }
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112 | acc += (u16_t)htons((u16_t)proto);
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113 | acc += ((u16_t *)&proto_len)[0] & 0xffff;
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114 | acc += ((u16_t *)&proto_len)[1] & 0xffff;
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115 |
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116 | while (acc >> 16) {
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117 | acc = (acc & 0xffff) + (acc >> 16);
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118 | }
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119 | return ~(acc & 0xffff);
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120 | }
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121 |
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122 | /* inet_chksum:
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123 | *
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124 | * Calculates the Internet checksum over a portion of memory. Used primarely for IP
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125 | * and ICMP.
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126 | */
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127 |
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128 | u16_t
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129 | inet_chksum(void *dataptr, u16_t len)
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130 | {
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131 | u32_t acc, sum;
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132 |
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133 | acc = chksum(dataptr, len);
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134 | sum = (acc & 0xffff) + (acc >> 16);
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135 | sum += (sum >> 16);
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136 | return ~(sum & 0xffff);
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137 | }
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138 |
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139 | u16_t
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140 | inet_chksum_pbuf(struct pbuf *p)
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141 | {
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142 | u32_t acc;
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143 | struct pbuf *q;
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144 | u8_t swapped;
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145 |
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146 | acc = 0;
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147 | swapped = 0;
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148 | for(q = p; q != NULL; q = q->next) {
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149 | acc += chksum(q->payload, q->len);
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150 | while (acc >> 16) {
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151 | acc = (acc & 0xffff) + (acc >> 16);
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152 | }
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153 | if (q->len % 2 != 0) {
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154 | swapped = 1 - swapped;
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155 | acc = (acc & 0xff << 8) | (acc & 0xff00 >> 8);
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156 | }
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157 | }
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158 |
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159 | if (swapped) {
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160 | acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
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161 | }
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162 | return ~(acc & 0xffff);
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163 | }
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