1 | /* |
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2 | * Copyright (c) 1988, 1992, 1993 |
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3 | * The Regents of the University of California. All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * 1. Redistributions of source code must retain the above copyright |
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9 | * notice, this list of conditions and the following disclaimer. |
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10 | * 2. Redistributions in binary form must reproduce the above copyright |
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11 | * notice, this list of conditions and the following disclaimer in the |
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12 | * documentation and/or other materials provided with the distribution. |
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13 | * 3. All advertising materials mentioning features or use of this software |
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14 | * must display the following acknowledgement: |
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15 | * This product includes software developed by the University of |
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16 | * California, Berkeley and its contributors. |
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17 | * 4. Neither the name of the University nor the names of its contributors |
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18 | * may be used to endorse or promote products derived from this software |
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19 | * without specific prior written permission. |
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20 | * |
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21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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31 | * SUCH DAMAGE. |
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32 | * |
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33 | * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 |
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34 | * $Id$ |
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35 | */ |
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36 | |
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37 | #include <sys/param.h> |
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38 | #include <sys/mbuf.h> |
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39 | |
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40 | /* |
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41 | * Try to use a CPU specific version, then punt to the portable C one. |
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42 | */ |
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43 | |
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44 | #if (defined(__GNUC__) && (defined(__mc68000__) || defined(__m68k__))) |
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45 | |
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46 | #include "in_cksum_m68k.c" |
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47 | |
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48 | #elif (defined(__GNUC__) && defined(__i386__)) |
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49 | |
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50 | #include "in_cksum_i386.c" |
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51 | |
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52 | #else |
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53 | |
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54 | /* |
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55 | * Checksum routine for Internet Protocol family headers (Portable Version). |
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56 | * |
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57 | * This routine is very heavily used in the network |
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58 | * code and should be modified for each CPU to be as fast as possible. |
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59 | */ |
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60 | |
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61 | #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) |
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62 | #define REDUCE \ |
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63 | {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} |
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64 | |
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65 | int |
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66 | in_cksum(m, len) |
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67 | register struct mbuf *m; |
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68 | register int len; |
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69 | { |
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70 | register u_short *w; |
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71 | register int sum = 0; |
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72 | register int mlen = 0; |
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73 | int byte_swapped = 0; |
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74 | |
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75 | union { |
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76 | char c[2]; |
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77 | u_short s; |
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78 | } s_util; |
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79 | union { |
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80 | u_short s[2]; |
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81 | long l; |
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82 | } l_util; |
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83 | |
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84 | for (;m && len; m = m->m_next) { |
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85 | if (m->m_len == 0) |
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86 | continue; |
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87 | w = mtod(m, u_short *); |
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88 | if (mlen == -1) { |
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89 | /* |
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90 | * The first byte of this mbuf is the continuation |
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91 | * of a word spanning between this mbuf and the |
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92 | * last mbuf. |
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93 | * |
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94 | * s_util.c[0] is already saved when scanning previous |
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95 | * mbuf. |
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96 | */ |
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97 | s_util.c[1] = *(char *)w; |
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98 | sum += s_util.s; |
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99 | w = (u_short *)((char *)w + 1); |
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100 | mlen = m->m_len - 1; |
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101 | len--; |
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102 | } else |
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103 | mlen = m->m_len; |
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104 | if (len < mlen) |
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105 | mlen = len; |
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106 | len -= mlen; |
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107 | /* |
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108 | * Force to even boundary. |
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109 | */ |
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110 | if ((1 & (int) w) && (mlen > 0)) { |
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111 | REDUCE; |
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112 | sum <<= 8; |
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113 | s_util.c[0] = *(u_char *)w; |
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114 | w = (u_short *)((char *)w + 1); |
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115 | mlen--; |
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116 | byte_swapped = 1; |
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117 | } |
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118 | /* |
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119 | * Unroll the loop to make overhead from |
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120 | * branches &c small. |
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121 | */ |
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122 | while ((mlen -= 32) >= 0) { |
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123 | sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; |
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124 | sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; |
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125 | sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; |
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126 | sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; |
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127 | w += 16; |
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128 | } |
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129 | mlen += 32; |
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130 | while ((mlen -= 8) >= 0) { |
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131 | sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; |
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132 | w += 4; |
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133 | } |
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134 | mlen += 8; |
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135 | if (mlen == 0 && byte_swapped == 0) |
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136 | continue; |
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137 | REDUCE; |
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138 | while ((mlen -= 2) >= 0) { |
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139 | sum += *w++; |
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140 | } |
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141 | if (byte_swapped) { |
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142 | REDUCE; |
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143 | sum <<= 8; |
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144 | byte_swapped = 0; |
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145 | if (mlen == -1) { |
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146 | s_util.c[1] = *(char *)w; |
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147 | sum += s_util.s; |
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148 | mlen = 0; |
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149 | } else |
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150 | mlen = -1; |
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151 | } else if (mlen == -1) |
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152 | s_util.c[0] = *(char *)w; |
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153 | } |
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154 | if (len) |
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155 | puts("cksum: out of data"); |
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156 | if (mlen == -1) { |
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157 | /* The last mbuf has odd # of bytes. Follow the |
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158 | standard (the odd byte may be shifted left by 8 bits |
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159 | or not as determined by endian-ness of the machine) */ |
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160 | s_util.c[1] = 0; |
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161 | sum += s_util.s; |
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162 | } |
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163 | REDUCE; |
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164 | return (~sum & 0xffff); |
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165 | } |
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166 | #endif |
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