/*
 * This file is distributed as part of the SkySQL Gateway. It 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,
 * version 2.
 * 
 * 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., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 * 
 * Copyright SkySQL Ab 2013
 * 
 */

/**
 * @file utils.c - General utility functions
 *
 * @verbatim
 * Revision History
 *
 * Date		Who			Description
 * 10-06-2013	Massimiliano Pinto	Initial implementation
 * 12-06-2013	Massimiliano Pinto	Read function trought 
 * 					the gwbuff strategy
 * 13-06-2013	Massimiliano Pinto	Gateway local authentication
 *					basics
 *
 * @endverbatim
 */


#include <gw.h>
#include <dcb.h>
#include <session.h>
#include <mysql_protocol.h>
#include <openssl/sha.h>
#include <poll.h>

// used in the hex2bin function
#define char_val(X) (X >= '0' && X <= '9' ? X-'0' :\
                     X >= 'A' && X <= 'Z' ? X-'A'+10 :\
                     X >= 'a' && X <= 'z' ? X-'a'+10 :\
                     '\177')

// used in the bin2hex function
char hex_upper[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char hex_lower[] = "0123456789abcdefghijklmnopqrstuvwxyz";

//////////////////////////////////////////
//backend read event triggered by EPOLLIN
//////////////////////////////////////////


int setnonblocking(int fd) {
	int fl;

	if ((fl = fcntl(fd, F_GETFL, 0)) == -1) {
		fprintf(stderr, "Can't GET fcntli for %i, errno = %d, %s", fd, errno, strerror(errno));
		return 1;
	}

	if (fcntl(fd, F_SETFL, fl | O_NONBLOCK) == -1) {
		fprintf(stderr, "Can't SET fcntl for %i, errno = %d, %s", fd, errno, strerror(errno));
		return 1;
	}

	return 0;
}

char *gw_strend(register const char *s) {
	while (*s++);
	return (char*) (s-1);
}

///////////////////////////////
// generate a random char 
//////////////////////////////
static char gw_randomchar() {
   return (char)((rand() % 78) + 30);
}

/////////////////////////////////
// generate a random string
// output must be pre allocated
/////////////////////////////////
int gw_generate_random_str(char *output, int len) {

	int i;
	srand(time(0L));

	for ( i = 0; i < len; ++i ) {
		output[i] = gw_randomchar();
	}

	output[len]='\0';

	return 0;
}

/////////////////////////////////
// hex string to binary data
// output must be pre allocated
/////////////////////////////////
int gw_hex2bin(uint8_t *out, const char *in, unsigned int len) {
	const char *in_end= in + len;

	if (len == 0 || in == NULL) {
		return 1;
	}

	while (in < in_end) {
		register unsigned char b1 = char_val(*in);
		uint8_t b2 = 0;
		in++;
		b2 =  (b1 << 4) | char_val(*in);
		*out++ = b2;

		in++;
	}

	return 0;
}

/////////////////////////////////
// binary data to hex string
// output must be pre allocated
/////////////////////////////////
char *gw_bin2hex(char *out, const uint8_t *in, unsigned int len) {
	const uint8_t *in_end= in + len;
	if (len == 0 || in == NULL) {
		return NULL;
	}

	for (; in != in_end; ++in) {
		*out++= hex_upper[((uint8_t) *in) >> 4];
		*out++= hex_upper[((uint8_t) *in) & 0x0F];
	}
	*out= '\0';

	return out;
}

///////////////////////////////////////////////////////
// fill a preallocated buffer with XOR(str1, str2)
// XOR between 2 equal len strings
// note that XOR(str1, XOR(str1 CONCAT str2)) == str2
// and that  XOR(str1, str2) == XOR(str2, str1)
///////////////////////////////////////////////////////
void gw_str_xor(uint8_t *output, const uint8_t *input1, const uint8_t *input2, unsigned int len) {
	const uint8_t *input1_end = NULL;
	input1_end = input1 + len;

	while (input1 < input1_end)
		*output++= *input1++ ^ *input2++;

	*output = '\0';
}

/////////////////////////////////////////////////////////////
// fill a 20 bytes preallocated with SHA1 digest (160 bits)
// for one input on in_len bytes
/////////////////////////////////////////////////////////////
void gw_sha1_str(const uint8_t *in, int in_len, uint8_t *out) {
	unsigned char hash[SHA_DIGEST_LENGTH];

	SHA1(in, in_len, hash);
	memcpy(out, hash, SHA_DIGEST_LENGTH);
}

/////////////////////////////////////////////////////////////
// fill 20 bytes preallocated with SHA1 digest (160 bits)
// for two inputs, in_len and in2_len bytes
/////////////////////////////////////////////////////////////
void gw_sha1_2_str(const uint8_t *in, int in_len, const uint8_t *in2, int in2_len, uint8_t *out) {
	SHA_CTX context;
	unsigned char hash[SHA_DIGEST_LENGTH];

	SHA1_Init(&context);
	SHA1_Update(&context, in, in_len);
	SHA1_Update(&context, in2, in2_len);
	SHA1_Final(hash, &context);

	memcpy(out, hash, SHA_DIGEST_LENGTH);
}