BachelorThesis/demo.c

/*
Author: Jozef Simko
School year: 3., Bachelor study, 2021/22
Study program: Computer Networks
Organization: Technical University of Kosice (TUKE), Faculty of Electrical Engineering and Informatics (FEI),
Compiler: Winlibs GCC -- MinGW-W64 x86_64-posix-seh version 11.2.0, built by Brecht Sanders (OS Win)
			-- gcc version 9.3.0 (OS Linux)
compile: WIN -- gcc client.c -Wall -Wextra -lwsock32 -o client
	LINUX -- gcc server.c -Wall -Wextra -o server
version: 1.2 , 15.5.2021
Usage: This demo demonstrates simple way of using Socket API and loading measurements from our server.
	Results are compared with MAX and MIN value - be careful on used units.

*/

#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <winsock2.h>
#else
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* Defines lenght of buffer for server's messages
It's better to use higher values, it's helpful in case of hardware/network overload */
#define REPLY_MSG_SIZE 2048

/* Defines public or local IP address of server in decimal form */
#define IP_ADDRESS "192.168.0.101"

/* Defines port used by server */
#define PORT 32500

/* MAX & MIN values are used to compare measurement result
Values should be adjusted to the used units (check server config file) */
#define MAX_VALUE 1265
#define MIN_VALUE 1200

/*
Closes socket (with dependency on used OS)
*/
void cleanUP(int sock){
#ifdef WIN32
	closesocket(sock);
	WSACleanup();
#else
	close(sock);
#endif
	return;
}

/* ====================================================== */

int main(){
	int sock;
	struct sockaddr_in server;
	char server_reply[REPLY_MSG_SIZE];

#ifdef WIN32
        WSADATA wsaData;
        int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
        if (iResult != 0){
                printf("WSASturtup() failed %d\n", iResult);
                return 1;
        }
#endif

	if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0){
		printf("socket() failed\n");
		cleanUP(sock);
		return 1;
	}

	memset(&server, 0, sizeof(server));
	server.sin_family = AF_INET;
	server.sin_addr.s_addr = inet_addr(IP_ADDRESS);
	server.sin_port = htons(PORT);

	if (connect(sock, (struct sockaddr *) &server, sizeof(server)) != 0){
		printf("Cannot connect to server - check IP, port and server status!\n");
		cleanUP(sock);
		return 1;
	}

	if(recv(sock, server_reply, 2, 0) <= 0){
		printf("Connection interrupted! Check server status!\n");
		cleanUP(sock);
		return 1;
	}

	while(1){
		memset(server_reply, 0, REPLY_MSG_SIZE);

		if(recv(sock, server_reply, REPLY_MSG_SIZE, 0) <= 0){
			printf("Server crushed or disconnected!\n");
			cleanUP(sock);
			return 1;
		}

		if(strcmp(server_reply, "%") == 0){
			break;
		}

		char *rest = server_reply;
		for(int i = 0; i < 3; i++){
			strtok_r(rest, ":", &rest);
		}
		double result = strtof(rest, NULL);

		if(result > MAX_VALUE){
			printf("Distance out of range - too great (%0.2f)\n", result);
		}
		if(result < MIN_VALUE){
			printf("Distance out of range - too low (%0.2f)\n", result);
		}
	}

	cleanUP(sock);
	return 0;
}