/*
* Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
*
* 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 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.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdint.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <assert.h>
#include <ipxe/base64.h>
/** @file
*
* Base64 encoding
*
*/
static const char base64[64] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/**
* Base64-encode data
*
* @v raw Raw data
* @v len Length of raw data
* @v encoded Buffer for encoded string
*
* The buffer must be the correct length for the encoded string. Use
* something like
*
* char buf[ base64_encoded_len ( len ) + 1 ];
*
* (the +1 is for the terminating NUL) to provide a buffer of the
* correct size.
*/
void base64_encode ( const uint8_t *raw, size_t len, char *encoded ) {
const uint8_t *raw_bytes = ( ( const uint8_t * ) raw );
uint8_t *encoded_bytes = ( ( uint8_t * ) encoded );
size_t raw_bit_len = ( 8 * len );
unsigned int bit;
unsigned int byte;
unsigned int shift;
unsigned int tmp;
for ( bit = 0 ; bit < raw_bit_len ; bit += 6 ) {
byte = ( bit / 8 );
shift = ( bit % 8 );
tmp = ( raw_bytes[byte] << shift );
if ( ( byte + 1 ) < len )
tmp |= ( raw_bytes[ byte + 1 ] >> ( 8 - shift ) );
tmp = ( ( tmp >> 2 ) & 0x3f );
*(encoded_bytes++) = base64[tmp];
}
for ( ; ( bit % 8 ) != 0 ; bit += 6 )
*(encoded_bytes++) = '=';
*(encoded_bytes++) = '\0';
DBG ( "Base64-encoded to \"%s\":\n", encoded );
DBG_HDA ( 0, raw, len );
assert ( strlen ( encoded ) == base64_encoded_len ( len ) );
}
/**
* Base64-decode string
*
* @v encoded Encoded string
* @v raw Raw data
* @ret len Length of raw data, or negative error
*
* The buffer must be large enough to contain the decoded data. Use
* something like
*
* char buf[ base64_decoded_max_len ( encoded ) ];
*
* to provide a buffer of the correct size.
*/
int base64_decode ( const char *encoded, uint8_t *raw ) {
const uint8_t *encoded_bytes = ( ( const uint8_t * ) encoded );
uint8_t *raw_bytes = ( ( uint8_t * ) raw );
uint8_t encoded_byte;
char *match;
int decoded;
unsigned int bit = 0;
unsigned int pad_count = 0;
size_t len;
/* Zero the raw data */
memset ( raw, 0, base64_decoded_max_len ( encoded ) );
/* Decode string */
while ( ( encoded_byte = *(encoded_bytes++) ) ) {
/* Ignore whitespace characters */
if ( isspace ( encoded_byte ) )
continue;
/* Process pad characters */
if ( encoded_byte == '=' ) {
if ( pad_count >= 2 ) {
DBG ( "Base64-encoded string \"%s\" has too "
"many pad characters\n", encoded );
return -EINVAL;
}
pad_count++;
bit -= 2; /* unused_bits = ( 2 * pad_count ) */
continue;
}
if ( pad_count ) {
DBG ( "Base64-encoded string \"%s\" has invalid pad "
"sequence\n", encoded );
return -EINVAL;
}
/* Process normal characters */
match = strchr ( base64, encoded_byte );
if ( ! match ) {
DBG ( "Base64-encoded string \"%s\" contains invalid "
"character '%c'\n", encoded, encoded_byte );
return -EINVAL;
}
decoded = ( match - base64 );
/* Add to raw data */
decoded <<= 2;
raw_bytes[ bit / 8 ] |= ( decoded >> ( bit % 8 ) );
raw_bytes[ bit / 8 + 1 ] |= ( decoded << ( 8 - ( bit % 8 ) ) );
bit += 6;
}
/* Check that we decoded a whole number of bytes */
if ( ( bit % 8 ) != 0 ) {
DBG ( "Base64-encoded string \"%s\" has invalid bit length "
"%d\n", encoded, bit );
return -EINVAL;
}
len = ( bit / 8 );
DBG ( "Base64-decoded \"%s\" to:\n", encoded );
DBG_HDA ( 0, raw, len );
assert ( len <= base64_decoded_max_len ( encoded ) );
/* Return length in bytes */
return ( len );
}
