checksum.c

   1 /*
   2  * Routines to support checksumming of bytes.
   3  *
   4  * Copyright (C) 1996 Andrew Tridgell
   5  * Copyright (C) 1996 Paul Mackerras
   6  * Copyright (C) 2004-2009 Wayne Davison
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 3 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, visit the http://fsf.org website.
  20  */
  21
  22 #include "rsync.h"
  23
  24 extern int checksum_seed;
  25 extern int protocol_version;
  26
  27 /*
  28   a simple 32 bit checksum that can be upadted from either end
  29   (inspired by Mark Adler's Adler-32 checksum)
  30   */
  31 uint32 get_checksum1(char *buf1, int32 len)
  32 {
  33     int32 i;
  34     uint32 s1, s2;
  35     schar *buf = (schar *)buf1;
  36
  37     s1 = s2 = 0;
  38     for (i = 0; i < (len-4); i+=4) {
  39         s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3] +
  40           10*CHAR_OFFSET;
  41         s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
  42     }
  43     for (; i < len; i++) {
  44         s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
  45     }
  46     return (s1 & 0xffff) + (s2 << 16);
  47 }
  48
  49
  50 void get_checksum2(char *buf, int32 len, char *sum)
  51 {
  52         md_context m;
  53
  54         if (protocol_version >= 30) {
  55                 uchar seedbuf[4];
  56                 md5_begin(&m);
  57                 md5_update(&m, (uchar *)buf, len);
  58                 if (checksum_seed) {
  59                         SIVALu(seedbuf, 0, checksum_seed);
  60                         md5_update(&m, seedbuf, 4);
  61                 }
  62                 md5_result(&m, (uchar *)sum);
  63         } else {
  64                 int32 i;
  65                 static char *buf1;
  66                 static int32 len1;
  67
  68                 mdfour_begin(&m);
  69
  70                 if (len > len1) {
  71                         if (buf1)
  72                                 free(buf1);
  73                         buf1 = new_array(char, len+4);
  74                         len1 = len;
  75                         if (!buf1)
  76                                 out_of_memory("get_checksum2");
  77                 }
  78
  79                 memcpy(buf1, buf, len);
  80                 if (checksum_seed) {
  81                         SIVAL(buf1,len,checksum_seed);
  82                         len += 4;
  83                 }
  84
  85                 for (i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK)
  86                         mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
  87
  88                 /*
  89                  * Prior to version 27 an incorrect MD4 checksum was computed
  90                  * by failing to call mdfour_tail() for block sizes that
  91                  * are multiples of 64.  This is fixed by calling mdfour_update()
  92                  * even when there are no more bytes.
  93                  */
  94                 if (len - i > 0 || protocol_version >= 27)
  95                         mdfour_update(&m, (uchar *)(buf1+i), len-i);
  96
  97                 mdfour_result(&m, (uchar *)sum);
  98         }
  99 }
 100
 101 void file_checksum(char *fname, char *sum, OFF_T size)
 102 {
 103         struct map_struct *buf;
 104         OFF_T i, len = size;
 105         md_context m;
 106         int32 remainder;
 107         int fd;
 108
 109         memset(sum, 0, MAX_DIGEST_LEN);
 110
 111         fd = do_open(fname, O_RDONLY, 0);
 112         if (fd == -1)
 113                 return;
 114
 115         buf = map_file(fd, size, MAX_MAP_SIZE, CSUM_CHUNK);
 116
 117         if (protocol_version >= 30) {
 118                 md5_begin(&m);
 119
 120                 for (i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
 121                         md5_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
 122                                    CSUM_CHUNK);
 123                 }
 124
 125                 remainder = (int32)(len - i);
 126                 if (remainder > 0)
 127                         md5_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
 128
 129                 md5_result(&m, (uchar *)sum);
 130         } else {
 131                 mdfour_begin(&m);
 132
 133                 for (i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
 134                         mdfour_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
 135                                       CSUM_CHUNK);
 136                 }
 137
 138                 /* Prior to version 27 an incorrect MD4 checksum was computed
 139                  * by failing to call mdfour_tail() for block sizes that
 140                  * are multiples of 64.  This is fixed by calling mdfour_update()
 141                  * even when there are no more bytes. */
 142                 remainder = (int32)(len - i);
 143                 if (remainder > 0 || protocol_version >= 27)
 144                         mdfour_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
 145
 146                 mdfour_result(&m, (uchar *)sum);
 147         }
 148
 149         close(fd);
 150         unmap_file(buf);
 151 }
 152
 153 static int32 sumresidue;
 154 static md_context md;
 155
 156 void sum_init(int seed)
 157 {
 158         char s[4];
 159
 160         if (protocol_version >= 30)
 161                 md5_begin(&md);
 162         else {
 163                 mdfour_begin(&md);
 164                 sumresidue = 0;
 165                 SIVAL(s, 0, seed);
 166                 sum_update(s, 4);
 167         }
 168 }
 169
 170 /**
 171  * Feed data into an MD4 accumulator, md.  The results may be
 172  * retrieved using sum_end().  md is used for different purposes at
 173  * different points during execution.
 174  *
 175  * @todo Perhaps get rid of md and just pass in the address each time.
 176  * Very slightly clearer and slower.
 177  **/
 178 void sum_update(const char *p, int32 len)
 179 {
 180         if (protocol_version >= 30) {
 181                 md5_update(&md, (uchar *)p, len);
 182                 return;
 183         }
 184
 185         if (len + sumresidue < CSUM_CHUNK) {
 186                 memcpy(md.buffer + sumresidue, p, len);
 187                 sumresidue += len;
 188                 return;
 189         }
 190
 191         if (sumresidue) {
 192                 int32 i = CSUM_CHUNK - sumresidue;
 193                 memcpy(md.buffer + sumresidue, p, i);
 194                 mdfour_update(&md, (uchar *)md.buffer, CSUM_CHUNK);
 195                 len -= i;
 196                 p += i;
 197         }
 198
 199         while (len >= CSUM_CHUNK) {
 200                 mdfour_update(&md, (uchar *)p, CSUM_CHUNK);
 201                 len -= CSUM_CHUNK;
 202                 p += CSUM_CHUNK;
 203         }
 204
 205         sumresidue = len;
 206         if (sumresidue)
 207                 memcpy(md.buffer, p, sumresidue);
 208 }
 209
 210 int sum_end(char *sum)
 211 {
 212         if (protocol_version >= 30) {
 213                 md5_result(&md, (uchar *)sum);
 214                 return MD5_DIGEST_LEN;
 215         }
 216
 217         if (sumresidue || protocol_version >= 27)
 218                 mdfour_update(&md, (uchar *)md.buffer, sumresidue);
 219
 220         mdfour_result(&md, (uchar *)sum);
 221
 222         return MD4_DIGEST_LEN;
 223 }