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/*
* base64.c
*
* Base64 encoding/decoding, code
*
* Copyright (c) 2000 Virtual Unlimited B.V.
*
* Author: Bob Deblier <bob@virtualunlimited.com>
*
* This library 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 library 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 library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#define BEECRYPT_DLL_EXPORT
#include "base64.h"
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if HAVE_STRING_H
#include <string.h>
#endif
#if HAVE_CTYPE_H
#include <ctype.h>
#endif
static const char* to_b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/* encode 72 characters per line */
#define CHARS_PER_LINE 72
char* b64enc(const memchunk* chunk)
{
int div = chunk->size / 3;
int rem = chunk->size % 3;
int chars = div*4 + rem + 1;
int newlines = (chars + CHARS_PER_LINE - 1) / CHARS_PER_LINE;
const byte* data = chunk->data;
char* string = (char*) malloc(chars + newlines + 1);
if (string)
{
register char* buf = string;
chars = 0;
while (div > 0)
{
buf[0] = to_b64[ (data[0] >> 2) & 0x3f];
buf[1] = to_b64[((data[0] << 4) & 0x30) + ((data[1] >> 4) & 0xf)];
buf[2] = to_b64[((data[1] << 2) & 0x3c) + ((data[2] >> 6) & 0x3)];
buf[3] = to_b64[ data[2] & 0x3f];
data += 3;
buf += 4;
div--;
chars += 4;
if (chars == CHARS_PER_LINE)
{
chars = 0;
*(buf++) = '\n';
}
}
switch (rem)
{
case 2:
buf[0] = to_b64[ (data[0] >> 2) & 0x3f];
buf[1] = to_b64[((data[0] << 4) & 0x30) + ((data[1] >> 4) & 0xf)];
buf[2] = to_b64[ (data[1] << 2) & 0x3c];
buf[3] = '=';
buf += 4;
chars += 4;
break;
case 1:
buf[0] = to_b64[ (data[0] >> 2) & 0x3f];
buf[1] = to_b64[ (data[0] << 4) & 0x30];
buf[2] = '=';
buf[3] = '=';
buf += 4;
chars += 4;
break;
}
*(buf++) = '\n';
*buf = '\0';
}
return string;
}
memchunk* b64dec(const char* string)
{
/* return a decoded memchunk, or a null pointer in case of failure */
memchunk* rc = 0;
if (string)
{
register int length = strlen(string);
/* do a format verification first */
if (length > 0)
{
register int count = 0, rem = 0;
register const char* tmp = string;
while (length > 0)
{
register int skip = strspn(tmp, to_b64);
count += skip;
length -= skip;
tmp += skip;
if (length > 0)
{
register int i, vrfy = strcspn(tmp, to_b64);
for (i = 0; i < vrfy; i++)
{
if (isspace(tmp[i]))
continue;
if (tmp[i] == '=')
{
/* we should check if we're close to the end of the string */
rem = count % 4;
/* rem must be either 2 or 3, otherwise no '=' should be here */
if (rem < 2)
return 0;
/* end-of-message recognized */
break;
}
else
{
/* Transmission error; RFC tells us to ignore this, but:
* - the rest of the message is going to even more corrupt since we're sliding bits out of place
* If a message is corrupt, it should be dropped. Period.
*/
return 0;
}
}
length -= vrfy;
tmp += vrfy;
}
}
rc = (memchunk*) malloc(sizeof(memchunk));
if (rc)
{
rc->size = (count / 4) * 3 + (rem ? (rem - 1) : 0);
if (count > 0)
{
rc->data = (byte*) malloc(rc->size);
if (rc->data)
{
register int i, qw = 0, tw = 0;
register byte* data = rc->data;
length = strlen(tmp = string);
for (i = 0; i < length; i++)
{
register char ch = string[i];
register byte bits;
if (isspace(ch))
continue;
if ((ch >= 'A') && (ch <= 'Z'))
{
bits = (byte) (ch - 'A');
}
else if ((ch >= 'a') && (ch <= 'z'))
{
bits = (byte) (ch - 'a' + 26);
}
else if ((ch >= '0') && (ch <= '9'))
{
bits = (byte) (ch - '0' + 52);
}
else if (ch == '=')
break;
switch (qw++)
{
case 0:
data[tw+0] = (bits << 2) & 0xfc;
break;
case 1:
data[tw+0] |= (bits >> 4) & 0x03;
data[tw+1] = (bits << 4) & 0xf0;
break;
case 2:
data[tw+1] |= (bits >> 2) & 0x0f;
data[tw+2] = (bits << 6) & 0xc0;
break;
case 3:
data[tw+2] |= bits & 0x3f;
break;
}
if (qw == 4)
{
qw = 0;
tw += 3;
}
}
}
else
{
free(rc);
rc = (memchunk*) 0;
}
}
else
rc->data = (byte*) 0;
}
}
}
return rc;
}
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