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/*
* base64.c - Base 64 encoding/decoding implementation
* Copyright (C) 2006 Collabora Ltd.
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config.h"
#include "base64.h"
#define DEBUG_FLAG GABBLE_DEBUG_VCARD
#include "debug.h"
#include <ctype.h>
#include <string.h>
/*
|AAAA AABB|BBBB CCCC|CCDD DDDD|
0xFC = 1111 1100
0x03 = 0000 0011
0xF0 = 1111 0000
0x0F = 0000 1111
0xC0 = 1100 0000
0x3F = 0011 1111
3 input bytes = 4 output bytes;
2 input bytes = 2 output bytes;
1 input byte = 1 output byte.
*/
static const gchar *encoding =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const guint decoding[256] =
{
/* ... */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0,
/* + */
62,
/* ... */
0, 0, 0,
/* / , 0-9 */
63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
/* ... */
0, 0, 0, 0, 0, 0, 0,
/* A */
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
/* ... */
0, 0, 0, 0, 0, 0,
/* a */
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
};
#define GET_6_BITS_0(s) (((s)[0] & 0xFC) >> 2)
#define GET_6_BITS_1(s) (((s)[0] & 0x03) << 4) | \
(((s)[1] & 0xF0) >> 4)
#define GET_6_BITS_2(s) (((s)[1] & 0x0F) << 2) | \
(((s)[2] & 0xC0) >> 6)
#define GET_6_BITS_3(s) (((s)[2] & 0x3F) << 0)
#define GET_BYTE_0(s) (((decoding[(guchar)(s)[0]] & 0x3F) << 2) | \
((decoding[(guchar)(s)[1]] & 0x30) >> 4))
#define GET_BYTE_1(s) (((decoding[(guchar)(s)[1]] & 0x0F) << 4) | \
((decoding[(guchar)(s)[2]] & 0x3C) >> 2))
#define GET_BYTE_2(s) (((decoding[(guchar)(s)[2]] & 0x03) << 6) | \
((decoding[(guchar)(s)[3]] & 0xFF) << 0))
gchar *base64_encode (guint len, const gchar *str, gboolean split_lines)
{
guint i;
GString *tmp;
/* TODO: calculate requisite output string length and allocate that big a
* GString */
tmp = g_string_new ("");
for (i = 0; i < len; i += 3)
{
guint c1, c2, c3, c4;
if (split_lines && i > 0 && (i * 4) % 76 == 0)
g_string_append_c (tmp, '\n');
switch (i + 3 - len)
{
case 1:
c1 = encoding[GET_6_BITS_0 (str + i)];
c2 = encoding[GET_6_BITS_1 (str + i)];
/* can't use GET_6_BITS_2 because str[i+2] is out of range */
c3 = encoding[(str[i + 1] & 0x0f) << 2];
c4 = '=';
break;
case 2:
c1 = encoding[GET_6_BITS_0 (str + i)];
/* can't use GET_6_BITS_1 because str[i+1] is out of range */
c2 = encoding[(str[i] & 0x03) << 4];
c3 = '=';
c4 = '=';
break;
default:
c1 = encoding[GET_6_BITS_0 (str + i)];
c2 = encoding[GET_6_BITS_1 (str + i)];
c3 = encoding[GET_6_BITS_2 (str + i)];
c4 = encoding[GET_6_BITS_3 (str + i)];
}
g_string_append_printf (tmp, "%c%c%c%c", c1, c2, c3, c4);
}
return g_string_free (tmp, FALSE);
}
GString *base64_decode (const gchar *str)
{
guint i;
GString *tmp;
char group[4];
guint filled = 0;
for (i = 0; str[i]; i++)
{
if (str[i] != 'A' &&
str[i] != '=' &&
!isspace (str[i]) &&
decoding[(guchar) str[i]] == 0)
{
DEBUG ("bad character %x at byte %u", (guchar)str[i], i);
return NULL;
}
}
tmp = g_string_new ("");
for (i = 0; str[i]; i++)
{
if (isspace (str[i]))
continue;
group[filled++] = str[i];
if (filled == 4)
{
if (group[3] == '=')
{
if (group[2] == '=')
{
g_string_append_c (tmp, GET_BYTE_0(group));
}
else
{
g_string_append_c (tmp, GET_BYTE_0(group));
g_string_append_c (tmp, GET_BYTE_1(group));
}
}
else
{
g_string_append_c (tmp, GET_BYTE_0(group));
g_string_append_c (tmp, GET_BYTE_1(group));
g_string_append_c (tmp, GET_BYTE_2(group));
}
filled = 0;
}
}
if (filled)
{
DEBUG ("insufficient padding at end of base64 string:\n%s", str);
g_string_free (tmp, TRUE);
return NULL;
}
return tmp;
}
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