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/*
* Routines to support checksumming of bytes.
*
* Copyright (C) 1996 Andrew Tridgell
* Copyright (C) 1996 Paul Mackerras
* Copyright (C) 2004, 2005 Wayne Davison
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "rsync.h"
int csum_length=2; /* initial value */
#define CSUM_CHUNK 64
extern int checksum_seed;
extern int protocol_version;
/*
a simple 32 bit checksum that can be upadted from either end
(inspired by Mark Adler's Adler-32 checksum)
*/
uint32 get_checksum1(char *buf1, int32 len)
{
int32 i;
uint32 s1, s2;
schar *buf = (schar *)buf1;
s1 = s2 = 0;
for (i = 0; i < (len-4); i+=4) {
s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3] +
10*CHAR_OFFSET;
s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
}
for (; i < len; i++) {
s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
}
return (s1 & 0xffff) + (s2 << 16);
}
void get_checksum2(char *buf, int32 len, char *sum)
{
int32 i;
static char *buf1;
static int32 len1;
struct mdfour m;
if (len > len1) {
if (buf1)
free(buf1);
buf1 = new_array(char, len+4);
len1 = len;
if (!buf1)
out_of_memory("get_checksum2");
}
mdfour_begin(&m);
memcpy(buf1,buf,len);
if (checksum_seed) {
SIVAL(buf1,len,checksum_seed);
len += 4;
}
for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
}
/*
* Prior to version 27 an incorrect MD4 checksum was computed
* by failing to call mdfour_tail() for block sizes that
* are multiples of 64. This is fixed by calling mdfour_update()
* even when there are no more bytes.
*/
if (len - i > 0 || protocol_version >= 27) {
mdfour_update(&m, (uchar *)(buf1+i), (len-i));
}
mdfour_result(&m, (uchar *)sum);
}
void file_checksum(char *fname,char *sum,OFF_T size)
{
struct map_struct *buf;
OFF_T i, len = size;
struct mdfour m;
int32 remainder;
int fd;
memset(sum,0,MD4_SUM_LENGTH);
fd = do_open(fname, O_RDONLY, 0);
if (fd == -1)
return;
buf = map_file(fd, size, MAX_MAP_SIZE, CSUM_CHUNK);
mdfour_begin(&m);
for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
mdfour_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
CSUM_CHUNK);
}
/* Prior to version 27 an incorrect MD4 checksum was computed
* by failing to call mdfour_tail() for block sizes that
* are multiples of 64. This is fixed by calling mdfour_update()
* even when there are no more bytes. */
remainder = (int32)(len - i);
if (remainder > 0 || protocol_version >= 27)
mdfour_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
mdfour_result(&m, (uchar *)sum);
close(fd);
unmap_file(buf);
}
static int32 sumresidue;
static char sumrbuf[CSUM_CHUNK];
static struct mdfour md;
void sum_init(int seed)
{
char s[4];
mdfour_begin(&md);
sumresidue = 0;
SIVAL(s, 0, seed);
sum_update(s, 4);
}
/**
* Feed data into an MD4 accumulator, md. The results may be
* retrieved using sum_end(). md is used for different purposes at
* different points during execution.
*
* @todo Perhaps get rid of md and just pass in the address each time.
* Very slightly clearer and slower.
**/
void sum_update(const char *p, int32 len)
{
if (len + sumresidue < CSUM_CHUNK) {
memcpy(sumrbuf + sumresidue, p, len);
sumresidue += len;
return;
}
if (sumresidue) {
int32 i = CSUM_CHUNK - sumresidue;
memcpy(sumrbuf + sumresidue, p, i);
mdfour_update(&md, (uchar *)sumrbuf, CSUM_CHUNK);
len -= i;
p += i;
}
while (len >= CSUM_CHUNK) {
mdfour_update(&md, (uchar *)p, CSUM_CHUNK);
len -= CSUM_CHUNK;
p += CSUM_CHUNK;
}
sumresidue = len;
if (sumresidue)
memcpy(sumrbuf, p, sumresidue);
}
void sum_end(char *sum)
{
if (sumresidue || protocol_version >= 27)
mdfour_update(&md, (uchar *)sumrbuf, sumresidue);
mdfour_result(&md, (uchar *)sum);
}
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