TCP_Client.cpp

// LoginClient.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <stdio.h>
#include <conio.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <string.h>
#include <stdlib.h>
#define _CRT_SECURE_NO_WARNINGS
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#define SERVER_PORT 7225
#define SERVER_ADDR "127.0.0.1"
#define BUFF_SIZE 2048
#undef UNICODE

//Error code for USERID
#define USER_OK "00"
#define USER_VOID "01"      // User doesnot exist
#define USER_DISABLED "02"  // User is locked
#define USER_NULL "03"      // User has not entered UID

// Error code for PASSWORD
#define PASS_OK "10"
#define PASS_INCORRECT "11"
#define PASS_NULL "12"

// Error code for LOGOUT
#define LOGOUT_SUCCESS "20"
#define USER_NOT_AUTHENTICATED "21"

// Error code for LOGIN
#define LOGIN_SUCCESS "30"
#define USER_AUTHENTICATED "31"

// Error code for EXIT
#define EXIT_OK  "40"
#define EXIT_FAIL "41"

// Other error code
#define SYNTAX_ERROR "51"
#define NO_OPTION "52"

// Code for kind of message
#define USER_PREFIX "USER"
#define PASSWORD_PREFIX "PASS"
#define LOGOUT_PREFIX "LOUT"
#define LOGIN_PREFIX "LGIN"
#define EXIT_PREFIX "EXIT"
#define OTHER_OPTION "OTHR"

// Status for connection
#define AUTHENTICATED 0
#define NOT_AUTHENTICATED 1
#define NOT_IDENTIFIED 2
#define NO_CONNECTION 3

// link with Ws2_32.lib
#pragma comment (lib, "Ws2_32.lib")
#pragma warning(disable : 4996)

void printMenu();
void chopNChars(char *, int);
void logIn(SOCKET);
void logOut(SOCKET);
void exitProgram(SOCKET);

int main(int argc, char *argv[]) {
    // Initiate WinSock
    WSADATA wsaData;
    WORD wVersion = MAKEWORD(2, 2);
    if (WSAStartup(wVersion, &wsaData)) {
        printf("Version is not supported!\n");
    }

    // Specify server address
    sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_addr.s_addr = inet_addr(SERVER_ADDR);
    serverAddr.sin_port = htons(SERVER_PORT);

    // Construct socket
    SOCKET client;
    client = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    // (optional) Set time-out for receiving
    int tv = 10000; // Time-out interval: 10000ms
    setsockopt(client, SOL_SOCKET, SO_RCVTIMEO, (const char *)(&tv), sizeof(int));

    // Message to send to client
    char choice[BUFF_SIZE];

    // Request to connect server
    if (connect(client, (sockaddr *)&serverAddr, sizeof(serverAddr))) {
        printf("Error! Cannot connect to server!\nError code: %d\n", WSAGetLastError());
        return 0;
    }
    printf("Server connected!\n");

    while (1) {

        // Print MENU
        printMenu();

        // Choose function of the system
        printf("Your option: ");
        gets_s(choice, BUFF_SIZE);

        // Send log in request to server
        if (atoi(choice) == 1) {
            logIn(client);
        }

        // Send log out request to server
        else if (atoi(choice) == 2) {
            logOut(client);
        }

        // Send exit request to server
        else if (atoi(choice) == 3) {
            exitProgram(client);
            return 0;
        }

        // Notice the error
        else
            printf("No such option! Please try again!\n");

    }

    // Close socket
    closesocket(client);

    // Terminate Winsock
    WSACleanup();

    return 0;
}

// Function to cut n first character of
// a pointed string
void chopNChars(char *str, int n) {
    int strLen = strlen(str);
    if (n > strLen)
        return;
    memmove(str, str + n, strLen - n + 1);
}

// Funtion to print menu to client console
void printMenu() {
    printf("--------MENU--------\n");
    printf("1. Login system\n");
    printf("2. Logout\n");
    printf("3. Exit\n");
    printf("---------------------\n");
}

// Funtion to send username and password (login) to server
void logIn(SOCKET client) {
    int ret;

    char userID[] = USER_PREFIX;
    char buff[BUFF_SIZE] = { '\0' };
    // Enter UserID
    printf("USERNAME:");
    gets_s(buff, BUFF_SIZE);
    strcat(userID, buff);
    // Send UserID to server
    ret = send(client, userID, strlen(userID), 0);
    if (ret == SOCKET_ERROR)
        printf("Error! Cannot send message!\nError code: %i\n", WSAGetLastError());

    chopNChars(userID, 4);

    // Receive echo message
    ret = recv(client, buff, BUFF_SIZE, 0);
    buff[ret] = 0;
    if (ret == SOCKET_ERROR) {
        if (WSAGetLastError() == WSAETIMEDOUT)
            printf("Time-out!\n");
    }
    else if (strlen(buff) > 0) {
        // Check received code to know if the username is valid
        if (strcmp(buff, USER_OK) == 0) {
            // UserID has not been authenticated
            int countLeft = 3;

            // Enter password
            printf("PASSWORD:");
            char passwd[] = PASSWORD_PREFIX;
            gets_s(buff, BUFF_SIZE);
            strcat(passwd, buff);

            // Send password to server
            ret = send(client, passwd, strlen(passwd), 0);

            char buff2[BUFF_SIZE] = "\0";
            // Receive echo message
            ret = recv(client, buff2, BUFF_SIZE, 0);
            if (WSAGetLastError() == WSAETIMEDOUT)
                printf("Time-out!\n");

            buff2[ret] = 0;
            // Check if the password is correct
            if (strcmp(buff2, PASS_OK) == 0) {
                printf("Loggin in to the system!\n\n");
            }

            // The password is incorrect, warn user
            else if ((strcmp(buff2, PASS_INCORRECT) == 0) && (countLeft > 0)) {
                countLeft--;
                printf("Wrong password! %d times left!\n", countLeft);
            }

            // The userID has been locked from the system
            else if (strcmp(buff2, USER_DISABLED) == 0) {
                printf("UserID %s is locked! Please contact with admin for support!\n", userID);
            }
        }

        // The userID does not exist
        else if (strcmp(buff, USER_VOID) == 0) {
            printf("UserID not found!\n");
        }

        // The userID has been locked from the system
        else if (strcmp(buff, USER_DISABLED) == 0) {
            printf("UserID %s is locked! Please contact with admin for support!\n", userID);
        }
    }
}

// Funtion to send logout request to server
void logOut(SOCKET client) {
    int ret;
    char option2[BUFF_SIZE];
    ret = send(client, LOGOUT_PREFIX, strlen(LOGOUT_PREFIX), 0);
    if (ret == SOCKET_ERROR)
        printf("Error! Cannot send message!\nError code: %i\n", WSAGetLastError());

    ret = recv(client, option2, BUFF_SIZE, 0);
    if (WSAGetLastError() == WSAETIMEDOUT)
        printf("Time-out!\n");

    option2[ret] = 0;

    // Check if the logout request is success
    if (strcmp(option2, LOGOUT_SUCCESS) == 0) {
        printf("Logging out ... \n\n");
    }
    else if (strcmp(option2, USER_NOT_AUTHENTICATED) == 0) {
        printf("No account has logged in!\n\n");
    }
}

// Function to send exit request to server
void exitProgram(SOCKET client) {
    int ret;
    char option3[BUFF_SIZE];
    ret = send(client, EXIT_PREFIX, strlen(EXIT_PREFIX), 0);
    if (ret == SOCKET_ERROR)
        printf("Error! Cannot send message!\nError code: %i\n", WSAGetLastError());

    ret = recv(client, option3, BUFF_SIZE, 0);
    if (WSAGetLastError() == WSAETIMEDOUT)
        printf("Time-out!\n");

    option3[ret] = 0;

    if (strcmp(option3, EXIT_OK) == 0)
        printf("Exitting ... \n\n");
}