2 * Routines to support checksumming of bytes.
4 * Copyright (C) 1996 Andrew Tridgell
5 * Copyright (C) 1996 Paul Mackerras
6 * Copyright (C) 2004-2007 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 version 2 as
10 * published by the Free Software Foundation.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
24 int csum_length = SHORT_SUM_LENGTH; /* initial value */
28 extern int checksum_seed;
29 extern int protocol_version;
32 a simple 32 bit checksum that can be upadted from either end
33 (inspired by Mark Adler's Adler-32 checksum)
35 uint32 get_checksum1(char *buf1, int32 len)
39 schar *buf = (schar *)buf1;
42 for (i = 0; i < (len-4); i+=4) {
43 s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3] +
45 s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
47 for (; i < len; i++) {
48 s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
50 return (s1 & 0xffff) + (s2 << 16);
54 void get_checksum2(char *buf, int32 len, char *sum)
64 buf1 = new_array(char, len+4);
67 out_of_memory("get_checksum2");
74 SIVAL(buf1,len,checksum_seed);
78 for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
79 mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
82 * Prior to version 27 an incorrect MD4 checksum was computed
83 * by failing to call mdfour_tail() for block sizes that
84 * are multiples of 64. This is fixed by calling mdfour_update()
85 * even when there are no more bytes.
87 if (len - i > 0 || protocol_version >= 27) {
88 mdfour_update(&m, (uchar *)(buf1+i), (len-i));
91 mdfour_result(&m, (uchar *)sum);
95 void file_checksum(char *fname,char *sum,OFF_T size)
97 struct map_struct *buf;
103 memset(sum,0,MD4_SUM_LENGTH);
105 fd = do_open(fname, O_RDONLY, 0);
109 buf = map_file(fd, size, MAX_MAP_SIZE, CSUM_CHUNK);
113 for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
114 mdfour_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
118 /* Prior to version 27 an incorrect MD4 checksum was computed
119 * by failing to call mdfour_tail() for block sizes that
120 * are multiples of 64. This is fixed by calling mdfour_update()
121 * even when there are no more bytes. */
122 remainder = (int32)(len - i);
123 if (remainder > 0 || protocol_version >= 27)
124 mdfour_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
126 mdfour_result(&m, (uchar *)sum);
133 static int32 sumresidue;
134 static char sumrbuf[CSUM_CHUNK];
135 static struct mdfour md;
137 void sum_init(int seed)
147 * Feed data into an MD4 accumulator, md. The results may be
148 * retrieved using sum_end(). md is used for different purposes at
149 * different points during execution.
151 * @todo Perhaps get rid of md and just pass in the address each time.
152 * Very slightly clearer and slower.
154 void sum_update(const char *p, int32 len)
156 if (len + sumresidue < CSUM_CHUNK) {
157 memcpy(sumrbuf + sumresidue, p, len);
163 int32 i = CSUM_CHUNK - sumresidue;
164 memcpy(sumrbuf + sumresidue, p, i);
165 mdfour_update(&md, (uchar *)sumrbuf, CSUM_CHUNK);
170 while (len >= CSUM_CHUNK) {
171 mdfour_update(&md, (uchar *)p, CSUM_CHUNK);
178 memcpy(sumrbuf, p, sumresidue);
181 void sum_end(char *sum)
183 if (sumresidue || protocol_version >= 27)
184 mdfour_update(&md, (uchar *)sumrbuf, sumresidue);
186 mdfour_result(&md, (uchar *)sum);