Untitled

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>

#define PORT_NO 9001
#define CLIENTS 5

char* handle_input ( char *data);

pthread_mutex_t lock_file; // mutex lock for file access

typedef struct {

    struct sockaddr_in adres;
    int address_length;
    int bind_result;

} connect__data;


void *handle_client(void *arg) {
    int new_socket = *((int *) arg);

    /* --------------------------------------------------------------------------------*/

    // Receive the client request using recv() system call

    char buffer[1024];
    int bytes_received = recv(new_socket, buffer, 1024, 0);
    if (bytes_received < 0) {
        printf("Error receiving client request\n");
        return NULL;
    }

    buffer[bytes_received] = '\0';

    // Close the socket

    char* message = handle_input(buffer);

    // Send the message to the client
    int bytes_sent = send(new_socket, message, strlen(message), 0);
    if (bytes_sent < 0) {
        printf("Error sending message to client\n");
    }

    close(new_socket);

    // Mutex lock to protect the critical section
    static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
    pthread_mutex_lock(&lock);

    // Access the shared resources
    FILE* file = fopen("server_records.txt", "a");
    if (file == NULL) {
        printf("Failed to open server_records.txt for writing\n");
    } else {
        char* file_msg = malloc(1024 * sizeof(char));
        sprintf(file_msg, "Client request: %s\nServer response: %s\n\n", buffer, message);
        fprintf(file, "%s", file_msg);
        fclose(file);
        free(file_msg);
    }

    pthread_mutex_unlock(&lock);

    return NULL;
}


char* handle_input(char* data) {
    int i = 1;
    int k = 0;
    char seat_type[50];
    char number_of_seats[50];

    while (*data != ':') {
        seat_type[k++] = *(data++);
    }
    seat_type[k] = '\0';

    data++; // Skip the ':' character

    int p = 0;
    while (*data != '\0') {
        number_of_seats[p++] = *(data++);
    }
    number_of_seats[p] = '\0';

    char* msg = NULL;
    char* file_msg = malloc(1024 * sizeof(char));

    pthread_mutex_lock(&lock_file); // lock file access

    FILE* file = fopen("Seat_Availability.txt", "r+");
    if (file == NULL) {
        printf("Failed to get the available seats data\n");
        pthread_mutex_unlock(&lock_file);
        return msg;
    }

    int found = 0;
    char line[500], avl_seats[50];
    while (fgets(line, sizeof(line), file) != NULL) {
        char* token = strtok(line, " ");
        if (strcmp(token, seat_type) == 0) {
            token = strtok(NULL, " ");
            strcpy(avl_seats, token);
            found = 1;
            break;
        }
    }

    if (found) {
        int required_seats = atoi(number_of_seats);
        int available_seats = atoi(avl_seats);
        int remaining_seats = 0;
        char seats_remain[50];

        if (required_seats > available_seats) {
            msg = "Required Number of Seats Not Available\0";
        } else {
            remaining_seats = available_seats - required_seats;
            sprintf(seats_remain, "%d", remaining_seats);
            fseek(file, -strlen(avl_seats) - 1, SEEK_CUR); // move the file pointer back to the start of the available seats value
            fprintf(file, "%s", seats_remain); // overwrite the old value with the new one
            fflush(file);
            sprintf(msg, "%d Seats have been booked for type %s", required_seats, seat_type);
            sprintf(file_msg, "FOR TYPE: %s\n%d Seats have been booked. %d Seats remaining\n\n", seat_type, required_seats, available_seats);
            FILE* new_file = fopen("server_records.txt", "a");
            if (new_file == NULL) {
                printf("Failed to open server_records.txt for writing\n");
            } else {
                fprintf(new_file, "%s", file_msg);
                fclose(new_file);
            }
        }
    } else {
        msg = "Seat type not found!\0";
    }

    fclose(file);
    pthread_mutex_unlock(&lock_file); // unlock file access

    return msg;
}



void handle_agent_login () {

    char* user_id = "Agent123";
    char* password = "123456";

    char input_id[100];
    char input_pass[100];

    do {

        puts("Agent Login:");
        printf("Enter User ID: ");

        fgets(input_id,100,stdin);

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

        printf("Enter Password: ");

        fgets(input_pass, 100, stdin);

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

        if ( strcmp(input_id,user_id) != 0 || strcmp(input_pass,password) != 0) {

            puts("Invalid Login Credentials, Please Try Again!\n");
        }

    } while ( strcmp(input_id,user_id) != 0 || strcmp(input_pass,password) != 0);

    return;


}

int create_socket () {

    int my_socket = socket(AF_INET, SOCK_STREAM, 0);

    if ( my_socket == -1 ) {
        printf("Socket Error!\n");
        return -1;
    } else {
        puts("Socket creation successful!");
    }

    return my_socket;

}

connect__data bind_port ( int sock ) {

    connect__data temp;

    struct sockaddr_in address;
    int adlength = sizeof(address);

    memset(&address, 0, sizeof(address));

        address.sin_family = AF_INET;
        address.sin_addr.s_addr = INADDR_ANY;
        address.sin_port = htons(PORT_NO);

        int opt = 1;
        if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) == -1) {
            printf("Error setting socket options!\n");
            exit(0);
        }

        int bind_res = bind(sock, (struct sockaddr*)&address, sizeof(address));

        if (bind_res == -1) {
            printf("Bind Error!\n");
            exit(0);
        } else {
            puts("Bind Successful!");
        }

        temp.adres = address;
        temp.address_length = adlength;
        temp.bind_result = bind_res;

        return temp;


}

int main() {



    handle_agent_login();

   

    int i = 1;
    struct sockaddr_in address;
    int adlength;
    
    //Create a socket using socket( ) system call.

    int sock = create_socket();

    if ( sock == -1 ) {
        printf("\n*************Socket Error!*******************\n");
    }
    
    /* --------------------------------------------------------------------------------*/

    //Bind server’s address and port using bind( ) system call.
        
    connect__data result = bind_port(sock);

    address = result.adres;
    adlength = result.address_length;
    int bind_res = result.bind_result;
    /* --------------------------------------------------------------------------------*/

    //Convert the socket into a listening socket using listen( ) system call.

    if ( listen(sock, CLIENTS) < 0 ) {
        printf("Listen Error!\n");
        return 1;
    } 

   
/* --------------------------------------------------------------------------------*/

//Accept client connections using accept( ) system call.

printf("\nServer is listening on port %d....\n\n", PORT_NO);

while (1) {

    
    int new_socket = accept(sock, (struct sockaddr*)&address, (socklen_t*)&adlength);

    if (new_socket < 0) {
        printf("Accept Error!\n");
        return 1;
    }

    printf("Client-%d connected\n",i);
    i++;

    // Create a new thread to handle the client request
    pthread_t client_thread;

    if (pthread_create(&client_thread, NULL, handle_client, (void*) &new_socket) < 0) {
        printf("Error creating thread for client\n");
        return 1;
    }
}

/* --------------------------------------------------------------------------------*/

//Close the socket

close(sock);

return 0;

}