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/*= -*- c-basic-offset: 4; indent-tabs-mode: nil; -*-
*
* librsync -- the library for network deltas
*
* Copyright (C) 2000 by Martin Pool <mbp@sourcefrog.net>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "config.h"
#include <stdlib.h>
#include <string.h>
#include "librsync.h"
/** Decode a base64 string in-place - simple and slow algorithm.
*
* See RFC1521 for the specification of base64. */
size_t rs_unbase64(char *s)
{
char const *b64 =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int bit_offset, byte_offset, idx, i, n;
unsigned char *d = (unsigned char *)s;
char *p;
n = i = 0;
while (*s && (p = strchr(b64, *s))) {
idx = (int)(p - b64);
byte_offset = (i * 6) / 8;
bit_offset = (i * 6) % 8;
d[byte_offset] &= ~((1 << (8 - bit_offset)) - 1);
if (bit_offset < 3) {
d[byte_offset] |= (idx << (2 - bit_offset));
n = byte_offset + 1;
} else {
d[byte_offset] |= (idx >> (bit_offset - 2));
d[byte_offset + 1] = 0;
d[byte_offset + 1] |= (idx << (8 - (bit_offset - 2))) & 0xFF;
n = byte_offset + 2;
}
s++;
i++;
}
return n;
}
/** Encode a buffer as base64 - simple and slow algorithm. */
void rs_base64(unsigned char const *buf, int n, char *out)
{
char const *b64 =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int bytes, i;
/* work out how many bytes of output there are */
bytes = ((n * 8) + 5) / 6;
for (i = 0; i < bytes; i++) {
int byte = (i * 6) / 8;
int bit = (i * 6) % 8;
if (bit < 3) {
if (byte >= n)
abort();
*out = b64[(buf[byte] >> (2 - bit)) & 0x3F];
} else {
if (byte + 1 == n) {
*out = b64[(buf[byte] << (bit - 2)) & 0x3F];
} else {
*out =
b64[(buf[byte] << (bit - 2) | buf[byte + 1] >> (10 - bit)) &
0x3F];
}
}
out++;
}
*out = 0;
}