BachelorThesis/client.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 , 17.5.2021
Usage: Program can communicate with second program (server) using sockets.
	It works in active or passive mode according to settings of server.
*/

#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>
#include <time.h>

/* Defines lenght of user input and output send to server
Should not be less than longest user command in commands.txt file */
#define MESSAGE_SIZE 16

/* 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 exact amount of user commands in commands.txt file and works as safety feature
Should not be less than number of lines in commands.txt file */
#define CMD_BUF_SIZE 13

/* Defines lenght of buffer used to read line from commands.txt file
Should not be less than the longest line in file commands.txt */
#define LINE_SIZE 256

/*###########################################
	       DEFINED FUNCTIONS
#############################################*/

/*
Writes input to log file with time stamp
*/
void write_log(FILE *log, char *mess){
	time_t rawtime;
        struct tm * timeinfo;

        time(&rawtime);
        timeinfo = localtime(&rawtime);

	mess[strcspn(mess, "\r")] = 0;

        fprintf (log, "%02d/%02d/%d - %02d:%02d:%02d: %s\n", timeinfo->tm_mday, timeinfo->tm_mon+1, timeinfo->tm_year+1900,
                timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec, mess);
	return;
}

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

/*
Frees allocated memory of pointer to array of chars
*/
void freeCMD(char *commands[], char *ls_commands[], char *description[], int i){
	for(int f=0; f < i; f++){
		free(commands[f]);
		free(ls_commands[f]);
		free(description[f]);
	}
	return;
}

/* ######################################### */

int main(int argc , char *argv[]){

	if (argc != 3){
		fprintf(stderr, "Usage:\n");
		fprintf(stderr, "- %s <Server IP> <Server Port>\n", argv[0]);
        	return 1;
	}

	int sock;
	struct sockaddr_in server;
	char message[MESSAGE_SIZE];
	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

	// Create socket
	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(argv[1]);
	server.sin_port = htons(atoi(argv[2]));

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

	memset(server_reply, 0, REPLY_MSG_SIZE);

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

	// Check server's mode
	int automatic = 0;
	if(strcmp(server_reply, "0") == 0){
		printf("Connected - manual mode.\n");
	}
	else{
		printf("Connected - automatic mode.\n");
		automatic = 1;
	}

	char *commands[CMD_BUF_SIZE];
	char *ls_commands[CMD_BUF_SIZE];
	char *description[CMD_BUF_SIZE];
	int i = 0;

	if(automatic == 0){

		// Load user commands
		FILE *fptr;
		if ((fptr = fopen("commands.txt", "r")) == NULL) {
			printf("Cannot open/create log file!\n");
			cleanUP(sock);
	       		return 1;
		}
		char line[LINE_SIZE];
		memset(line, 0, LINE_SIZE);
		while(fgets(line, sizeof(line), fptr) != NULL) {
			char *rest = line;
			char *cmd = strtok_r(line, ":", &rest);
			char *ls_cmd = strtok_r(rest, ":", &rest);
			char *des = strtok_r(rest, ":", &rest);
			commands[i] = (char *)calloc(strlen(cmd)+2, sizeof(char));
			strcpy(commands[i], cmd);

			ls_commands[i] = (char *)calloc(strlen(ls_cmd)+2, sizeof(char));
			strcpy(ls_commands[i], ls_cmd);

			description[i] = (char *)calloc(strlen(des)+2, sizeof(char));
			strcpy(description[i], des);
			i++;
		}
		fclose(fptr);
		puts("Commands loaded. Type 'show' or 'show info' to see more. Use 'close' for client shutdown.");
	}

	FILE *logs;

	// Communication with server
	while(1){
		memset(server_reply, 0, REPLY_MSG_SIZE);

		if(automatic == 0){
	       		logs = fopen("logy.txt", "a");

			if(logs == NULL){
				printf("Cannot open/create log file!\n");
				cleanUP(sock);
				return 1;
			}

			// Wait for, read and compare user input
			char message_lsm[MESSAGE_SIZE];
			memset(message_lsm, 0, MESSAGE_SIZE);

			printf(">> Enter command: ");

			memset(message, 0, MESSAGE_SIZE);
			char* r = fgets(message, MESSAGE_SIZE, stdin);
			if (r == NULL){
				printf("Input failed.\n");
				break;
			}

			if(strcmp(message, "\n") == 0){
				continue;
			}

			message[strcspn(message, "\n")] = 0;

			if(strcmp(message, "close") == 0){
				break;
			}

			if(strcmp(message, "show") == 0){
				for(int cmd = 0; cmd < i; cmd++){
					printf("%s\n", commands[cmd]);
				}
				printf("\n");
				continue;
			}
			else if(strcmp(message, "show info") == 0){
				for(int cmds = 0; cmds < i; cmds++){
					printf("%s - %s", commands[cmds], description[cmds]);
				}
				printf("\n");
				continue;
			}
			else{
				int check = 0;
				for(int y=0; y < i; y++){
					if(strcmp(message, commands[y]) == 0){
						strcpy(message_lsm, ls_commands[y]);
						write_log(logs, message_lsm);
						check = 1;
						fclose(logs);
					}
				}
				if(check == 0){
					printf("Invalid input. Try commands 'show' or 'show info' to check all avaible commands.\n");
					continue;
				}
			}

			// Send data
			if(send(sock, message_lsm, strlen(message_lsm), 0) < (ssize_t)strlen(message_lsm)){
				printf("send() failed");
				cleanUP(sock);
				freeCMD(commands, ls_commands, description, i);
				return 1;
			}


		}

		// Receive a reply from the server
		if(recv(sock, server_reply, REPLY_MSG_SIZE, 0) <= 0){
			printf("Server crashed or disconnected!\n");
			cleanUP(sock);
			if(automatic == 0){
				freeCMD(commands, ls_commands, description, i);
			}
			return 0;
		}

		// Write received data to logs and to terminal
		if(automatic == 0){
	       		logs = fopen("logy.txt", "a");

			if(logs == NULL){
				printf("Cannot create/write to log file!\n");
				cleanUP(sock);
				return 1;
			}

			puts("Server reply: ");
			write_log(logs, server_reply);
			printf("%s\n", server_reply);
			printf("\n");
			fprintf(logs, "\n");
			fclose(logs);
		}
		else{
			// Char % indicates end of measurement
			if(strcmp(server_reply, "%") == 0){
				break;
			}
			logs = fopen("auto-logy.txt", "a");
			if(logs == NULL){
				printf("Cannot open auto-log file!\n");
				cleanUP(sock);
				return 1;
			}

			fprintf(logs, "%s", server_reply);
			printf("%s", server_reply);
			fclose(logs);
		}
	}

	cleanUP(sock);
	return 0;
}