net/sctp/crc32c.c

   1 /* SCTP kernel reference Implementation
   2  * Copyright (c) 1999-2001 Motorola, Inc.
   3  * Copyright (c) 2001-2003 International Business Machines, Corp.
   4  *
   5  * This file is part of the SCTP kernel reference Implementation
   6  *
   7  * SCTP Checksum functions
   8  *
   9  * The SCTP reference implementation is free software;
  10  * you can redistribute it and/or modify it under the terms of
  11  * the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2, or (at your option)
  13  * any later version.
  14  *
  15  * The SCTP reference implementation is distributed in the hope that it
  16  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  17  *                 ************************
  18  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  19  * See the GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with GNU CC; see the file COPYING.  If not, write to
  23  * the Free Software Foundation, 59 Temple Place - Suite 330,
  24  * Boston, MA 02111-1307, USA.
  25  *
  26  * Please send any bug reports or fixes you make to the
  27  * email address(es):
  28  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  29  *
  30  * Or submit a bug report through the following website:
  31  *    http://www.sf.net/projects/lksctp
  32  *
  33  * Written or modified by:
  34  *    Dinakaran Joseph
  35  *    Jon Grimm <jgrimm@us.ibm.com>
  36  *    Sridhar Samudrala <sri@us.ibm.com>
  37  *
  38  * Any bugs reported given to us we will try to fix... any fixes shared will
  39  * be incorporated into the next SCTP release.
  40  */
  41
  42 /* The following code has been taken directly from
  43  * draft-ietf-tsvwg-sctpcsum-03.txt
  44  *
  45  * The code has now been modified specifically for SCTP knowledge.
  46  */
  47
  48 #include <linux/types.h>
  49 #include <net/sctp/sctp.h>
  50
  51 #define CRC32C_POLY 0x1EDC6F41
  52 #define CRC32C(c,d) (c=(c>>8)^crc_c[(c^(d))&0xFF])
  53 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  54 /* Copyright 2001, D. Otis.  Use this program, code or tables    */
  55 /* extracted from it, as desired without restriction.            */
  56 /*                                                               */
  57 /* 32 Bit Reflected CRC table generation for SCTP.               */
  58 /* To accommodate serial byte data being shifted out least       */
  59 /* significant bit first, the table's 32 bit words are reflected */
  60 /* which flips both byte and bit MS and LS positions.  The CRC   */
  61 /* is calculated MS bits first from the perspective of the serial*/
  62 /* stream.  The x^32 term is implied and the x^0 term may also   */
  63 /* be shown as +1.  The polynomial code used is 0x1EDC6F41.      */
  64 /* Castagnoli93                                                  */
  65 /* x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+  */
  66 /* x^11+x^10+x^9+x^8+x^6+x^0                                     */
  67 /* Guy Castagnoli Stefan Braeuer and Martin Herrman              */
  68 /* "Optimization of Cyclic Redundancy-Check Codes                */
  69 /* with 24 and 32 Parity Bits",                                  */
  70 /* IEEE Transactions on Communications, Vol.41, No.6, June 1993  */
  71 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  72 static const __u32 crc_c[256] = {
  73         0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4,
  74         0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
  75         0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B,
  76         0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
  77         0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B,
  78         0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
  79         0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54,
  80         0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
  81         0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A,
  82         0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
  83         0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5,
  84         0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
  85         0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45,
  86         0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
  87         0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A,
  88         0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
  89         0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48,
  90         0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
  91         0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687,
  92         0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
  93         0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927,
  94         0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
  95         0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8,
  96         0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
  97         0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096,
  98         0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
  99         0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859,
 100         0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
 101         0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9,
 102         0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
 103         0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36,
 104         0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
 105         0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C,
 106         0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
 107         0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043,
 108         0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
 109         0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3,
 110         0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
 111         0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C,
 112         0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
 113         0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652,
 114         0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
 115         0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D,
 116         0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
 117         0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D,
 118         0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
 119         0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2,
 120         0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
 121         0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530,
 122         0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
 123         0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF,
 124         0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
 125         0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F,
 126         0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
 127         0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90,
 128         0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
 129         0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE,
 130         0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
 131         0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321,
 132         0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
 133         0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81,
 134         0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
 135         0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E,
 136         0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351,
 137 };
 138
 139 __u32 sctp_start_cksum(__u8 *buffer, __u16 length)
 140 {
 141         __u32 crc32 = ~(__u32) 0;
 142         __u32 i;
 143
 144         /* Optimize this routine to be SCTP specific, knowing how
 145          * to skip the checksum field of the SCTP header.
 146          */
 147
 148         /* Calculate CRC up to the checksum. */
 149         for (i = 0; i < (sizeof(struct sctphdr) - sizeof(__u32)); i++)
 150                 CRC32C(crc32, buffer[i]);
 151
 152         /* Skip checksum field of the header. */
 153         for (i = 0; i < sizeof(__u32); i++)
 154                 CRC32C(crc32, 0);
 155
 156         /* Calculate the rest of the CRC. */
 157         for (i = sizeof(struct sctphdr); i < length ; i++)
 158                 CRC32C(crc32, buffer[i]);
 159
 160         return crc32;
 161 }
 162
 163 __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
 164 {
 165         __u32 i;
 166
 167         for (i = 0; i < length ; i++)
 168                 CRC32C(crc32, buffer[i]);
 169
 170         return crc32;
 171 }
 172
 173 __u32 sctp_update_copy_cksum(__u8 *to, __u8 *from, __u16 length, __u32 crc32)
 174 {
 175         __u32 i;
 176         __u32 *_to = (__u32 *)to;
 177         __u32 *_from = (__u32 *)from;
 178
 179         for (i = 0; i < (length/4); i++) {
 180                 _to[i] = _from[i];
 181                 CRC32C(crc32, from[i*4]);
 182                 CRC32C(crc32, from[i*4+1]);
 183                 CRC32C(crc32, from[i*4+2]);
 184                 CRC32C(crc32, from[i*4+3]);
 185         }
 186
 187         return crc32;
 188 }
 189
 190 __u32 sctp_end_cksum(__u32 crc32)
 191 {
 192         __u32 result;
 193         __u8 byte0, byte1, byte2, byte3;
 194
 195         result = ~crc32;
 196
 197         /*  result  now holds the negated polynomial remainder;
 198          *  since the table and algorithm is "reflected" [williams95].
 199          *  That is,  result has the same value as if we mapped the message
 200          *  to a polyomial, computed the host-bit-order polynomial
 201          *  remainder, performed final negation, then did an end-for-end
 202          *  bit-reversal.
 203          *  Note that a 32-bit bit-reversal is identical to four inplace
 204          *  8-bit reversals followed by an end-for-end byteswap.
 205          *  In other words, the bytes of each bit are in the right order,
 206          *  but the bytes have been byteswapped.  So we now do an explicit
 207          *  byteswap.  On a little-endian machine, this byteswap and
 208          *  the final ntohl cancel out and could be elided.
 209          */
 210         byte0 = result & 0xff;
 211         byte1 = (result>>8) & 0xff;
 212         byte2 = (result>>16) & 0xff;
 213         byte3 = (result>>24) & 0xff;
 214
 215         crc32 = ((byte0 << 24) |
 216                  (byte1 << 16) |
 217                  (byte2 << 8)  |
 218                  byte3);
 219         return crc32;
 220 }