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, 2005 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 2 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, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
21 */
22
23#include "rsync.h"
24
25int csum_length=2; /* initial value */
26
27#define CSUM_CHUNK 64
28
29extern int checksum_seed;
30extern int protocol_version;
31
32/*
33  a simple 32 bit checksum that can be upadted from either end
34  (inspired by Mark Adler's Adler-32 checksum)
35  */
36uint32 get_checksum1(char *buf1, int32 len)
37{
38    int32 i;
39    uint32 s1, s2;
40    schar *buf = (schar *)buf1;
41
42    s1 = s2 = 0;
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] +
45	  10*CHAR_OFFSET;
46	s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
47    }
48    for (; i < len; i++) {
49	s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
50    }
51    return (s1 & 0xffff) + (s2 << 16);
52}
53
54
55void get_checksum2(char *buf, int32 len, char *sum)
56{
57	int32 i;
58	static char *buf1;
59	static int32 len1;
60	struct mdfour m;
61
62	if (len > len1) {
63		if (buf1)
64			free(buf1);
65		buf1 = new_array(char, len+4);
66		len1 = len;
67		if (!buf1)
68			out_of_memory("get_checksum2");
69	}
70
71	mdfour_begin(&m);
72
73	memcpy(buf1,buf,len);
74	if (checksum_seed) {
75		SIVAL(buf1,len,checksum_seed);
76		len += 4;
77	}
78
79	for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
80		mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
81	}
82	/*
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.
87	 */
88	if (len - i > 0 || protocol_version >= 27) {
89		mdfour_update(&m, (uchar *)(buf1+i), (len-i));
90	}
91
92	mdfour_result(&m, (uchar *)sum);
93}
94
95
96void file_checksum(char *fname,char *sum,OFF_T size)
97{
98	OFF_T i;
99	struct map_struct *buf;
100	int fd;
101	OFF_T len = size;
102	struct mdfour m;
103
104	memset(sum,0,MD4_SUM_LENGTH);
105
106	fd = do_open(fname, O_RDONLY, 0);
107	if (fd == -1)
108		return;
109
110	buf = map_file(fd, size, MAX_MAP_SIZE, CSUM_CHUNK);
111
112	mdfour_begin(&m);
113
114	for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
115		mdfour_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
116			      CSUM_CHUNK);
117	}
118
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	if (len - i > 0 || protocol_version >= 27)
124		mdfour_update(&m, (uchar *)map_ptr(buf, i, len-i), len-i);
125
126	mdfour_result(&m, (uchar *)sum);
127
128	close(fd);
129	unmap_file(buf);
130}
131
132
133static int32 sumresidue;
134static char sumrbuf[CSUM_CHUNK];
135static struct mdfour md;
136
137void sum_init(int seed)
138{
139	char s[4];
140	mdfour_begin(&md);
141	sumresidue = 0;
142	SIVAL(s, 0, seed);
143	sum_update(s, 4);
144}
145
146/**
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.
150 *
151 * @todo Perhaps get rid of md and just pass in the address each time.
152 * Very slightly clearer and slower.
153 **/
154void sum_update(char *p, int32 len)
155{
156	if (len + sumresidue < CSUM_CHUNK) {
157		memcpy(sumrbuf + sumresidue, p, len);
158		sumresidue += len;
159		return;
160	}
161
162	if (sumresidue) {
163		int32 i = CSUM_CHUNK - sumresidue;
164		memcpy(sumrbuf + sumresidue, p, i);
165		mdfour_update(&md, (uchar *)sumrbuf, CSUM_CHUNK);
166		len -= i;
167		p += i;
168	}
169
170	while (len >= CSUM_CHUNK) {
171		mdfour_update(&md, (uchar *)p, CSUM_CHUNK);
172		len -= CSUM_CHUNK;
173		p += CSUM_CHUNK;
174	}
175
176	sumresidue = len;
177	if (sumresidue)
178		memcpy(sumrbuf, p, sumresidue);
179}
180
181void sum_end(char *sum)
182{
183	if (sumresidue || protocol_version >= 27)
184		mdfour_update(&md, (uchar *)sumrbuf, sumresidue);
185
186	mdfour_result(&md, (uchar *)sum);
187}
188