2 * Routines to support checksumming of bytes.
4 * Copyright (C) 1996 Andrew Tridgell
5 * Copyright (C) 1996 Paul Mackerras
6 * Copyright (C) 2004-2008 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 3 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, visit the http://fsf.org website.
24 extern int checksum_seed;
25 extern int protocol_version;
27 int csum_length = SHORT_SUM_LENGTH; /* initial value */
30 a simple 32 bit checksum that can be upadted from either end
31 (inspired by Mark Adler's Adler-32 checksum)
33 uint32 get_checksum1(char *buf1, int32 len)
37 schar *buf = (schar *)buf1;
40 for (i = 0; i < (len-4); i+=4) {
41 s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3] +
43 s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
45 for (; i < len; i++) {
46 s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
48 return (s1 & 0xffff) + (s2 << 16);
52 void get_checksum2(char *buf, int32 len, char *sum)
56 if (protocol_version >= 30) {
59 md5_update(&m, (uchar *)buf, len);
61 SIVAL(seedbuf, 0, checksum_seed);
62 md5_update(&m, seedbuf, 4);
64 md5_result(&m, (uchar *)sum);
75 buf1 = new_array(char, len+4);
78 out_of_memory("get_checksum2");
81 memcpy(buf1, buf, len);
83 SIVAL(buf1,len,checksum_seed);
87 for (i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK)
88 mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
91 * Prior to version 27 an incorrect MD4 checksum was computed
92 * by failing to call mdfour_tail() for block sizes that
93 * are multiples of 64. This is fixed by calling mdfour_update()
94 * even when there are no more bytes.
96 if (len - i > 0 || protocol_version >= 27)
97 mdfour_update(&m, (uchar *)(buf1+i), len-i);
99 mdfour_result(&m, (uchar *)sum);
103 void file_checksum(char *fname, char *sum, OFF_T size)
105 struct map_struct *buf;
111 memset(sum, 0, MAX_DIGEST_LEN);
113 fd = do_open(fname, O_RDONLY, 0);
117 buf = map_file(fd, size, MAX_MAP_SIZE, CSUM_CHUNK);
119 if (protocol_version >= 30) {
122 for (i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
123 md5_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
127 remainder = (int32)(len - i);
129 md5_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
131 md5_result(&m, (uchar *)sum);
135 for (i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
136 mdfour_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
140 /* Prior to version 27 an incorrect MD4 checksum was computed
141 * by failing to call mdfour_tail() for block sizes that
142 * are multiples of 64. This is fixed by calling mdfour_update()
143 * even when there are no more bytes. */
144 remainder = (int32)(len - i);
145 if (remainder > 0 || protocol_version >= 27)
146 mdfour_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
148 mdfour_result(&m, (uchar *)sum);
155 static int32 sumresidue;
156 static md_context md;
158 void sum_init(int seed)
162 if (protocol_version >= 30)
173 * Feed data into an MD4 accumulator, md. The results may be
174 * retrieved using sum_end(). md is used for different purposes at
175 * different points during execution.
177 * @todo Perhaps get rid of md and just pass in the address each time.
178 * Very slightly clearer and slower.
180 void sum_update(const char *p, int32 len)
182 if (protocol_version >= 30) {
183 md5_update(&md, (uchar *)p, len);
187 if (len + sumresidue < CSUM_CHUNK) {
188 memcpy(md.buffer + sumresidue, p, len);
194 int32 i = CSUM_CHUNK - sumresidue;
195 memcpy(md.buffer + sumresidue, p, i);
196 mdfour_update(&md, (uchar *)md.buffer, CSUM_CHUNK);
201 while (len >= CSUM_CHUNK) {
202 mdfour_update(&md, (uchar *)p, CSUM_CHUNK);
209 memcpy(md.buffer, p, sumresidue);
212 int sum_end(char *sum)
214 if (protocol_version >= 30) {
215 md5_result(&md, (uchar *)sum);
216 return MD5_DIGEST_LEN;
219 if (sumresidue || protocol_version >= 27)
220 mdfour_update(&md, (uchar *)md.buffer, sumresidue);
222 mdfour_result(&md, (uchar *)sum);
224 return MD4_DIGEST_LEN;