1 /*
2  * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation; either version 2 of the
7  * License, or any later version.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17  */
18 
19 FILE_LICENCE ( GPL2_OR_LATER );
20 
21 #include <stdint.h>
22 #include <string.h>
23 #include <assert.h>
24 #include <gpxe/base64.h>
25 
26 /** @file
27  *
28  * Base64 encoding
29  *
30  */
31 
32 static const char base64[64] =
33 	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
34 
35 /**
36  * Base64-encode a string
37  *
38  * @v raw		Raw string
39  * @v encoded		Buffer for encoded string
40  *
41  * The buffer must be the correct length for the encoded string.  Use
42  * something like
43  *
44  *     char buf[ base64_encoded_len ( strlen ( raw ) ) + 1 ];
45  *
46  * (the +1 is for the terminating NUL) to provide a buffer of the
47  * correct size.
48  */
49 void base64_encode ( const char *raw, char *encoded ) {
50 	const uint8_t *raw_bytes = ( ( const uint8_t * ) raw );
51 	uint8_t *encoded_bytes = ( ( uint8_t * ) encoded );
52 	size_t raw_bit_len = ( 8 * strlen ( raw ) );
53 	unsigned int bit;
54 	unsigned int tmp;
55 
56 	for ( bit = 0 ; bit < raw_bit_len ; bit += 6 ) {
57 		tmp = ( ( raw_bytes[ bit / 8 ] << ( bit % 8 ) ) |
58 			( raw_bytes[ bit / 8 + 1 ] >> ( 8 - ( bit % 8 ) ) ) );
59 		tmp = ( ( tmp >> 2 ) & 0x3f );
60 		*(encoded_bytes++) = base64[tmp];
61 	}
62 	for ( ; ( bit % 8 ) != 0 ; bit += 6 )
63 		*(encoded_bytes++) = '=';
64 	*(encoded_bytes++) = '\0';
65 
66 	DBG ( "Base64-encoded \"%s\" as \"%s\"\n", raw, encoded );
67 	assert ( strlen ( encoded ) == base64_encoded_len ( strlen ( raw ) ) );
68 }
69