client.c

#include <sys/socket.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define PORT        9999
#define BUFFER_SIZE 1024

int main()
{
    int client_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (client_socket < 0)
    {
        printf("[!] Error when creating a socket!\n");
        exit(EXIT_FAILURE);
    }
    printf("[+] Socket is created\n");

    struct sockaddr_in server_address;
    server_address.sin_family      = AF_INET;
    server_address.sin_port        = htons(PORT);
    server_address.sin_addr.s_addr = inet_addr("127.0.0.1");

    if (connect(client_socket, (struct sockaddr *)&server_address, sizeof(server_address)) < 0)
    {
        printf("[!] Error when connecting!\n");
        close(client_socket);
        exit(EXIT_FAILURE);
    }
    printf("[+] Connected to the server\n");
    printf("[+] Type a message and press Enter. Type 'disconnect' to quit.\n");

    char input[BUFFER_SIZE];
    char buffer[BUFFER_SIZE];

    while (1)
    {
        printf("> ");
        fflush(stdout);

        if (fgets(input, BUFFER_SIZE, stdin) == NULL)
        {
            printf("[!] Error reading input\n");
            break;
        }

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

        if (strlen(input) == 0)
        {
            continue;
        }

        int bytes_sent = write(client_socket, input, strlen(input));
        if (bytes_sent < 0)
        {
            printf("[!] Error when sending data to the server!\n");
            break;
        }

        memset(buffer, 0, BUFFER_SIZE);
        int bytes_received = read(client_socket, buffer, BUFFER_SIZE - 1);
        if (bytes_received <= 0)
        {
            printf("[!] Server closed the connection\n");
            break;
        }

        printf("[+] Server: %s\n", buffer);

        if (strncmp(input, "disconnect", strlen("disconnect")) == 0)
        {
            printf("[+] Disconnected from server\n");
            break;
        }
    }

    close(client_socket);
    return 0;
}