util.c

/*
 * util.c
 * Amazon SimpleDB C bindings
 *
 * Created by Peter Macko on 11/26/08.
 *
 * Copyright 2009
 *      The President and Fellows of Harvard College.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "stdafx.h"
#include "util.h"

#ifdef USE_BASE64_OPENSSL
	#include <openssl/sha.h>
	#include <openssl/hmac.h>
	#include <openssl/evp.h>
	#include <openssl/bio.h>
	#include <openssl/buffer.h>
#else
	#include "base64.h"
#endif


/**
 * Perform a Base64 encoding
 * 
 * @param input the input buffer
 * @param length the length of the input
 * @param output the output buffer
 * @param olength the length of the output buffer
 * @return the length of the encoded message, or 0 if the output buffer is too small
 */
size_t base64(const unsigned char *input, size_t length, char* output, size_t olength)
{
#ifdef USE_BASE64_OPENSSL
	
	// Source: http://www.ioncannon.net/cc/34/howto-base64-encode-with-cc-and-openssl/
	
	BIO *bmem, *b64;
	BUF_MEM *bptr;
	
	b64 = BIO_new(BIO_f_base64());
	bmem = BIO_new(BIO_s_mem());
	b64 = BIO_push(b64, bmem);
	BIO_write(b64, input, length);
	BIO_flush(b64);
	BIO_get_mem_ptr(b64, &bptr);
	
	if (bptr->length >= olength) {
		BIO_free_all(b64);
		return 0;
	}
	
	memcpy(output, bptr->data, bptr->length-1);
	output[bptr->length-1] = '\0';
	
	size_t l = bptr->length-1;
	BIO_free_all(b64);
	
	return l;
	
#else
	
	return encode64((const char*) input, output, length);
	
#endif
}


/**
 * Compute the number of digits of a number
 * 
 * @param num the number
 * @param base the base
 * @return the number of digits
 */
int digits(int num, int base)
{
	int register d = 1;
	int register n;
	for (n = num; n >= base; n /= base) d++;
	return d;
}