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/*
* http_base64.c -- This file contains code for encoding strings with base64.
* Created: Christopher Blizzard <blizzard@appliedtheory.com>, 20-Nov-1998
* Author: Joe Orton <jeo101@york.ac.uk>
*
* Copyright (C) 1998 Free Software Foundation
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
const char b64_alphabet[65] = {
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/=" };
char *
http_base64_encode(const char *text) {
/* The tricky thing about this is doing the padding at the end,
* doing the bit manipulation requires a bit of concentration only */
char *buffer = NULL;
char *point = NULL;
int inlen = 0;
int outlen = 0;
/* check our args */
if (text == NULL)
return NULL;
/* Use 'buffer' to store the output. Work out how big it should be...
* This must be a multiple of 4 bytes */
inlen = strlen( text );
/* check our arg...avoid a pesky FPE */
if (inlen == 0)
{
buffer = malloc(sizeof(char));
buffer[0] = '\0';
return buffer;
}
outlen = (inlen*4)/3;
if( (inlen % 3) > 0 ) /* got to pad */
outlen += 4 - (inlen % 3);
buffer = malloc( outlen + 1 ); /* +1 for the \0 */
memset(buffer, 0, outlen + 1); /* initialize to zero */
/* now do the main stage of conversion, 3 bytes at a time,
* leave the trailing bytes (if there are any) for later */
for( point=buffer; inlen>=3; inlen-=3, text+=3 ) {
*(point++) = b64_alphabet[ *text>>2 ];
*(point++) = b64_alphabet[ (*text<<4 & 0x30) | *(text+1)>>4 ];
*(point++) = b64_alphabet[ (*(text+1)<<2 & 0x3c) | *(text+2)>>6 ];
*(point++) = b64_alphabet[ *(text+2) & 0x3f ];
}
/* Now deal with the trailing bytes */
if( inlen ) {
/* We always have one trailing byte */
*(point++) = b64_alphabet[ *text>>2 ];
*(point++) = b64_alphabet[ (*text<<4 & 0x30) |
(inlen==2?*(text+1)>>4:0) ];
*(point++) = (inlen==1?'=':b64_alphabet[ *(text+1)<<2 & 0x3c ] );
*(point++) = '=';
}
*point = '\0';
return buffer;
}
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