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/* base64-encode.c
*
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2002 Niels Mller
*
* The nettle 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.
*
* The nettle 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 the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include "base64.h"
#include <assert.h>
#include <stdlib.h>
#define TABLE_INVALID -1
#define TABLE_SPACE -2
#define TABLE_END -3
static const signed char
decode_table[0x100] =
{
-1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
void
base64_decode_init(struct base64_decode_ctx *ctx)
{
ctx->word = ctx->bits = 0;
ctx->status = BASE64_DECODE_OK;
}
unsigned
base64_decode_update(struct base64_decode_ctx *ctx,
uint8_t *dst,
unsigned length,
const uint8_t *src)
{
unsigned done = 0;
unsigned i;
if (ctx->status == BASE64_DECODE_ERROR)
return 0;
for (i = 0; i<length; i++)
{
int data = decode_table[src[i]];
switch(data)
{
default:
assert(data >= 0 && data < 0x40);
if (ctx->status != BASE64_DECODE_OK)
goto invalid;
ctx->word = ctx->word << 6 | data;
ctx->bits += 6;
if (ctx->bits >= 8)
{
ctx->bits -= 8;
dst[done++] = ctx->word >> ctx->bits;
}
break;
case TABLE_INVALID:
invalid:
ctx->status = BASE64_DECODE_ERROR;
return done;
case TABLE_SPACE:
/* Ignore */
break;
case TABLE_END:
if (!ctx->bits)
goto invalid;
if (ctx->word & ( (1<<ctx->bits) - 1))
/* We shouldn't have any leftover bits */
goto invalid;
ctx->status = BASE64_DECODE_END;
ctx->bits -= 2;
break;
}
}
assert(done <= BASE64_DECODE_LENGTH(length));
return done;
}
int
base64_decode_status(struct base64_decode_ctx *ctx)
{
switch (ctx->status)
{
case BASE64_DECODE_END:
case BASE64_DECODE_OK:
return ctx->bits == 0;
case BASE64_DECODE_ERROR:
return 0;
}
abort();
}