1 | #include <machine/rtems-bsd-user-space.h> |
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2 | |
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3 | /* |
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4 | * Copyright (c) 1998-2006 The TCPDUMP project |
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5 | * |
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6 | * Redistribution and use in source and binary forms, with or without |
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7 | * modification, are permitted provided that: (1) source code |
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8 | * distributions retain the above copyright notice and this paragraph |
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9 | * in its entirety, and (2) distributions including binary code include |
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10 | * the above copyright notice and this paragraph in its entirety in |
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11 | * the documentation or other materials provided with the distribution. |
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12 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND |
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13 | * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT |
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14 | * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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15 | * FOR A PARTICULAR PURPOSE. |
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16 | * |
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17 | * miscellaneous checksumming routines |
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18 | * |
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19 | * Original code by Hannes Gredler (hannes@juniper.net) |
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20 | */ |
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21 | |
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22 | #ifndef lint |
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23 | static const char rcsid[] _U_ = |
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24 | "@(#) $Header: /tcpdump/master/tcpdump/checksum.c,v 1.4 2006-09-25 09:23:32 hannes Exp $"; |
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25 | #endif |
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26 | |
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27 | #ifdef HAVE_CONFIG_H |
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28 | #include "config.h" |
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29 | #endif |
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30 | |
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31 | #include <tcpdump-stdinc.h> |
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32 | |
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33 | #include <stdio.h> |
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34 | #include <stdlib.h> |
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35 | #include <string.h> |
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36 | #include <assert.h> |
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37 | |
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38 | #include "interface.h" |
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39 | |
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40 | /* |
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41 | * CRC-10 table generated using the following Python snippet: |
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42 | |
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43 | import sys |
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44 | |
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45 | crc_table = [] |
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46 | for i in range(256): |
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47 | accum = i << 2 |
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48 | for j in range(8): |
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49 | accum <<= 1 |
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50 | if accum & 0x400: |
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51 | accum ^= 0x633 |
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52 | crc_table.append(accum) |
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53 | |
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54 | for i in range(len(crc_table)/8): |
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55 | for j in range(8): |
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56 | sys.stdout.write("0x%04x, " % crc_table[i*8+j]) |
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57 | sys.stdout.write("\n") |
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58 | |
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59 | */ |
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60 | static const u_int16_t crc10_table[256] = |
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61 | { |
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62 | 0x0000, 0x0233, 0x0255, 0x0066, 0x0299, 0x00aa, 0x00cc, 0x02ff, |
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63 | 0x0301, 0x0132, 0x0154, 0x0367, 0x0198, 0x03ab, 0x03cd, 0x01fe, |
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64 | 0x0031, 0x0202, 0x0264, 0x0057, 0x02a8, 0x009b, 0x00fd, 0x02ce, |
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65 | 0x0330, 0x0103, 0x0165, 0x0356, 0x01a9, 0x039a, 0x03fc, 0x01cf, |
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66 | 0x0062, 0x0251, 0x0237, 0x0004, 0x02fb, 0x00c8, 0x00ae, 0x029d, |
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67 | 0x0363, 0x0150, 0x0136, 0x0305, 0x01fa, 0x03c9, 0x03af, 0x019c, |
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68 | 0x0053, 0x0260, 0x0206, 0x0035, 0x02ca, 0x00f9, 0x009f, 0x02ac, |
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69 | 0x0352, 0x0161, 0x0107, 0x0334, 0x01cb, 0x03f8, 0x039e, 0x01ad, |
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70 | 0x00c4, 0x02f7, 0x0291, 0x00a2, 0x025d, 0x006e, 0x0008, 0x023b, |
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71 | 0x03c5, 0x01f6, 0x0190, 0x03a3, 0x015c, 0x036f, 0x0309, 0x013a, |
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72 | 0x00f5, 0x02c6, 0x02a0, 0x0093, 0x026c, 0x005f, 0x0039, 0x020a, |
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73 | 0x03f4, 0x01c7, 0x01a1, 0x0392, 0x016d, 0x035e, 0x0338, 0x010b, |
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74 | 0x00a6, 0x0295, 0x02f3, 0x00c0, 0x023f, 0x000c, 0x006a, 0x0259, |
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75 | 0x03a7, 0x0194, 0x01f2, 0x03c1, 0x013e, 0x030d, 0x036b, 0x0158, |
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76 | 0x0097, 0x02a4, 0x02c2, 0x00f1, 0x020e, 0x003d, 0x005b, 0x0268, |
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77 | 0x0396, 0x01a5, 0x01c3, 0x03f0, 0x010f, 0x033c, 0x035a, 0x0169, |
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78 | 0x0188, 0x03bb, 0x03dd, 0x01ee, 0x0311, 0x0122, 0x0144, 0x0377, |
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79 | 0x0289, 0x00ba, 0x00dc, 0x02ef, 0x0010, 0x0223, 0x0245, 0x0076, |
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80 | 0x01b9, 0x038a, 0x03ec, 0x01df, 0x0320, 0x0113, 0x0175, 0x0346, |
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81 | 0x02b8, 0x008b, 0x00ed, 0x02de, 0x0021, 0x0212, 0x0274, 0x0047, |
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82 | 0x01ea, 0x03d9, 0x03bf, 0x018c, 0x0373, 0x0140, 0x0126, 0x0315, |
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83 | 0x02eb, 0x00d8, 0x00be, 0x028d, 0x0072, 0x0241, 0x0227, 0x0014, |
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84 | 0x01db, 0x03e8, 0x038e, 0x01bd, 0x0342, 0x0171, 0x0117, 0x0324, |
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85 | 0x02da, 0x00e9, 0x008f, 0x02bc, 0x0043, 0x0270, 0x0216, 0x0025, |
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86 | 0x014c, 0x037f, 0x0319, 0x012a, 0x03d5, 0x01e6, 0x0180, 0x03b3, |
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87 | 0x024d, 0x007e, 0x0018, 0x022b, 0x00d4, 0x02e7, 0x0281, 0x00b2, |
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88 | 0x017d, 0x034e, 0x0328, 0x011b, 0x03e4, 0x01d7, 0x01b1, 0x0382, |
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89 | 0x027c, 0x004f, 0x0029, 0x021a, 0x00e5, 0x02d6, 0x02b0, 0x0083, |
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90 | 0x012e, 0x031d, 0x037b, 0x0148, 0x03b7, 0x0184, 0x01e2, 0x03d1, |
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91 | 0x022f, 0x001c, 0x007a, 0x0249, 0x00b6, 0x0285, 0x02e3, 0x00d0, |
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92 | 0x011f, 0x032c, 0x034a, 0x0179, 0x0386, 0x01b5, 0x01d3, 0x03e0, |
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93 | 0x021e, 0x002d, 0x004b, 0x0278, 0x0087, 0x02b4, 0x02d2, 0x00e1 |
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94 | }; |
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95 | |
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96 | static void |
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97 | init_crc10_table(void) |
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98 | { |
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99 | #define CRC10_POLYNOMIAL 0x633 |
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100 | register int i, j; |
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101 | register u_int16_t accum; |
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102 | u_int16_t verify_crc10_table[256]; |
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103 | |
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104 | for ( i = 0; i < 256; i++ ) |
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105 | { |
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106 | accum = ((unsigned short) i << 2); |
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107 | for ( j = 0; j < 8; j++ ) |
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108 | { |
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109 | if ((accum <<= 1) & 0x400) accum ^= CRC10_POLYNOMIAL; |
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110 | } |
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111 | verify_crc10_table[i] = accum; |
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112 | } |
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113 | assert(memcmp(verify_crc10_table, |
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114 | crc10_table, |
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115 | sizeof(verify_crc10_table)) == 0); |
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116 | #undef CRC10_POLYNOMIAL |
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117 | } |
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118 | |
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119 | u_int16_t |
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120 | verify_crc10_cksum(u_int16_t accum, const u_char *p, int length) |
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121 | { |
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122 | register int i; |
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123 | |
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124 | for ( i = 0; i < length; i++ ) |
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125 | { |
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126 | accum = ((accum << 8) & 0x3ff) |
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127 | ^ crc10_table[( accum >> 2) & 0xff] |
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128 | ^ *p++; |
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129 | } |
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130 | return accum; |
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131 | } |
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132 | |
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133 | /* precompute checksum tables */ |
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134 | void |
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135 | init_checksum(void) { |
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136 | |
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137 | init_crc10_table(); |
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138 | |
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139 | } |
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140 | |
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141 | /* |
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142 | * Creates the OSI Fletcher checksum. See 8473-1, Appendix C, section C.3. |
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143 | * The checksum field of the passed PDU does not need to be reset to zero. |
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144 | */ |
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145 | u_int16_t |
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146 | create_osi_cksum (const u_int8_t *pptr, int checksum_offset, int length) |
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147 | { |
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148 | |
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149 | int x; |
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150 | int y; |
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151 | u_int32_t mul; |
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152 | u_int32_t c0; |
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153 | u_int32_t c1; |
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154 | u_int16_t checksum; |
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155 | int index; |
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156 | |
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157 | c0 = 0; |
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158 | c1 = 0; |
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159 | |
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160 | for (index = 0; index < length; index++) { |
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161 | /* |
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162 | * Ignore the contents of the checksum field. |
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163 | */ |
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164 | if (index == checksum_offset || |
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165 | index == checksum_offset+1) { |
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166 | c1 += c0; |
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167 | pptr++; |
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168 | } else { |
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169 | c0 = c0 + *(pptr++); |
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170 | c1 += c0; |
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171 | } |
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172 | } |
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173 | |
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174 | c0 = c0 % 255; |
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175 | c1 = c1 % 255; |
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176 | |
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177 | mul = (length - checksum_offset)*(c0); |
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178 | |
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179 | x = mul - c0 - c1; |
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180 | y = c1 - mul - 1; |
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181 | |
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182 | if ( y >= 0 ) y++; |
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183 | if ( x < 0 ) x--; |
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184 | |
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185 | x %= 255; |
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186 | y %= 255; |
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187 | |
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188 | |
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189 | if (x == 0) x = 255; |
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190 | if (y == 0) y = 255; |
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191 | |
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192 | y &= 0x00FF; |
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193 | checksum = ((x << 8) | y); |
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194 | |
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195 | return checksum; |
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196 | } |
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