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/* ----------------------------------------------------------------------------
NSTX -- tunneling network-packets over DNS
(C) 2000 by Florian Heinz and Julien Oster
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., 675 Mass Ave, Cambridge, MA 02139, USA.
-------------------------------------------------------------------------- */
/* $Id: nstx_encode.c,v 1.17 2003/10/07 22:09:20 sky Exp $ */
#include <string.h>
#include <stdlib.h>
unsigned char map[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_1234567890";
unsigned char *revmap = NULL;
void init_revmap (void)
{
unsigned int i;
revmap = malloc(256);
for (i = 0; i < strlen((char*)map); i++)
revmap[map[i]] = i;
}
const unsigned char *
nstx_encode(const unsigned char *data, int len) {
int i = 0, off = 1, cut = 0;
static unsigned char *buf = NULL;
if (len % 3)
cut = 3 - len%3;
buf = realloc(buf, ((len+2)/3)*4+2);
buf[0] = map[cut];
while (i < len) {
buf[off + 0] = map[(data[i] & 252) >> 2];
buf[off + 1] = map[((data[i] & 3) << 4) | ((data[i+1] & 240) >> 4)];
buf[off + 2] = map[((data[i+1] & 15) << 2 ) | ((data[i+2] & 192) >> 6)];
buf[off + 3] = map[(data[i+2] & 63)];
i += 3;
off += 4;
}
buf[off] = '\0';
return buf;
}
const unsigned char *
nstx_decode(const unsigned char *data, int *rlen) {
int i = 0, off = 1;
int len;
static unsigned char *buf = NULL;
if (!revmap)
init_revmap();
len = strlen((char*)data);
buf = realloc(buf, ((len+3)/4)*3);
while (off+3 < len) {
buf[i+0] = (revmap[data[off]]<<2)|((revmap[data[off+1]]&48)>>4);
buf[i+1] = ((revmap[data[off+1]]&15)<<4)|((revmap[data[off+2]]&60)>>2);
buf[i+2] = ((revmap[data[off+2]]&3)<<6)|(revmap[data[off+3]]);
i += 3;
off += 4;
}
*rlen = i - revmap[data[0]];
return buf;
}
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