MySQL UDF for sha3 hash generation

sha3.c

/*
 * Copyright (c) 2018, brian
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
 */

/* 
 * File:   sha3.c
 * Author: brian
 *
 * Created on February 23, 2018, 2:15 PM
 */

/*
 * USAGE INSTRUCTIONS:
 * 
 * make sure libmysqlclient-dev and rhash is installed:
 * apt install libmysqlclient-dev rhash librhash-dev
 * 
 * Replace "/usr/lib/mysql/plugin" with your MySQL plugins directory (can be found by running "select @@plugin_dir;")
 * gcc -I/usr/include/mysql -o sha3.so -shared sha3.c -lrhash -fPIC && cp sha3.so /usr/lib/mysql/plugin/sha3.so
 * 
 * Then, on the server:
 * create function`sha3`returns string soname'sha3.so';
 * 
 * And use/test like:
 * select sha3('yeet',224);
 * 
 * Note: this function is intended to work EXACTLY like the native sha2 function, 
 *     so when MySQL eventually adds support for sha3, 
 *     the native function SHOULD seamlessly be used instead of this one.
 * 
 * Yeet!
 *  
 */

#ifdef STANDARD
/* STANDARD is defined, don't use any mysql functions */
#include <string.h>
#ifdef __WIN__
typedef unsigned __int64 ulonglong; /* Microsofts 64 bit types */
typedef __int64 longlong;
#else
typedef unsigned long long ulonglong;
typedef long long longlong;
#endif /*__WIN__*/
#else
#include <my_global.h>
#include <my_sys.h>
#if defined(MYSQL_SERVER)
#include <m_string.h>
#else
/* when compiled as standalone */
#include <string.h>
#endif
#endif
#include <mysql.h>

#include <rhash.h>

#ifdef HAVE_DLOPEN

my_bool sha3_init(UDF_INIT *initid, UDF_ARGS *args, char *message);
void sha3_deinit(UDF_INIT *initid);
char *sha3(UDF_INIT *initid __attribute__ ((unused)), UDF_ARGS *args, char *result, unsigned long *length, char *is_null, char *message __attribute__ ((unused)));

my_bool sha3_init(UDF_INIT *initid, UDF_ARGS *args, char *message) {
	if (args->arg_count != 2) {
		strcpy(message, "`sha3`() requires 2 parameters: the message part, and the bits");
		return 1;
	}

	args->arg_type[1] = INT_RESULT;

	initid->maybe_null = 1; //can return null

	return 0;
}

char *sha3(UDF_INIT *initid __attribute__ ((unused)), UDF_ARGS *args, char *result, unsigned long *length, char *is_null, char *message __attribute__ ((unused))) {

	long long int_val;
	int_val = *((long long*) args->args[1]);

	if (int_val == 0) {
		int_val = 256;
	}

	if (args->args[0] == NULL || args->args[1] == NULL ||
			(int_val != 224 && int_val != 256 && int_val != 384 && int_val != 512)) {
		*is_null = 1;
		return 0;
	}

	unsigned long len = int_val / 8;
	unsigned char hash[len];

	unsigned char *hex = malloc(sizeof (char) * ((len * 2) + 1));

	unsigned hash_id;

	switch (int_val) {
		case 224:
			hash_id = RHASH_SHA3_224;
			break;
		case 256:
			hash_id = RHASH_SHA3_256;
			break;
		case 384:
			hash_id = RHASH_SHA3_384;
			break;
		case 512:
			hash_id = RHASH_SHA3_512;
			break;
	}

	if (rhash_msg(hash_id, args->args[0], args->lengths[0], hash)) {
		*is_null = 1;
		return 0;
	}

	int i;
	for (i = 0; i < len; i++) {
		sprintf(hex + i * 2, "%02x", hash[i]);
	}

	*length = len * 2;
	return hex;
}

#endif /* HAVE_DLOPEN */