2 * Routines to support checksumming of bytes.
4 * Copyright (C) 1996 Andrew Tridgell
5 * Copyright (C) 1996 Paul Mackerras
6 * Copyright (C) 2004, 2005 Wayne Davison
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 2 of the License, or
11 * (at your option) any later version.
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.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
25 int csum_length=2; /* initial value */
29 extern int checksum_seed;
30 extern int protocol_version;
33 a simple 32 bit checksum that can be upadted from either end
34 (inspired by Mark Adler's Adler-32 checksum)
36 uint32 get_checksum1(char *buf1, int32 len)
40 schar *buf = (schar *)buf1;
43 for (i = 0; i < (len-4); i+=4) {
44 s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3] +
46 s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
48 for (; i < len; i++) {
49 s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
51 return (s1 & 0xffff) + (s2 << 16);
55 void get_checksum2(char *buf, int32 len, char *sum)
65 buf1 = new_array(char, len+4);
68 out_of_memory("get_checksum2");
75 SIVAL(buf1,len,checksum_seed);
79 for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
80 mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
83 * Prior to version 27 an incorrect MD4 checksum was computed
84 * by failing to call mdfour_tail() for block sizes that
85 * are multiples of 64. This is fixed by calling mdfour_update()
86 * even when there are no more bytes.
88 if (len - i > 0 || protocol_version >= 27) {
89 mdfour_update(&m, (uchar *)(buf1+i), (len-i));
92 mdfour_result(&m, (uchar *)sum);
96 void file_checksum(char *fname,char *sum,OFF_T size)
98 struct map_struct *buf;
104 memset(sum,0,MD4_SUM_LENGTH);
106 fd = do_open(fname, O_RDONLY, 0);
110 buf = map_file(fd, size, MAX_MAP_SIZE, CSUM_CHUNK);
114 for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
115 mdfour_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
119 /* Prior to version 27 an incorrect MD4 checksum was computed
120 * by failing to call mdfour_tail() for block sizes that
121 * are multiples of 64. This is fixed by calling mdfour_update()
122 * even when there are no more bytes. */
123 remainder = (int32)(len - i);
124 if (remainder > 0 || protocol_version >= 27)
125 mdfour_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
127 mdfour_result(&m, (uchar *)sum);
134 static int32 sumresidue;
135 static char sumrbuf[CSUM_CHUNK];
136 static struct mdfour md;
138 void sum_init(int seed)
148 * Feed data into an MD4 accumulator, md. The results may be
149 * retrieved using sum_end(). md is used for different purposes at
150 * different points during execution.
152 * @todo Perhaps get rid of md and just pass in the address each time.
153 * Very slightly clearer and slower.
155 void sum_update(const char *p, int32 len)
157 if (len + sumresidue < CSUM_CHUNK) {
158 memcpy(sumrbuf + sumresidue, p, len);
164 int32 i = CSUM_CHUNK - sumresidue;
165 memcpy(sumrbuf + sumresidue, p, i);
166 mdfour_update(&md, (uchar *)sumrbuf, CSUM_CHUNK);
171 while (len >= CSUM_CHUNK) {
172 mdfour_update(&md, (uchar *)p, CSUM_CHUNK);
179 memcpy(sumrbuf, p, sumresidue);
182 void sum_end(char *sum)
184 if (sumresidue || protocol_version >= 27)
185 mdfour_update(&md, (uchar *)sumrbuf, sumresidue);
187 mdfour_result(&md, (uchar *)sum);