ftp help in C

int
main(int argc, char *argv[])
{
    int c_sockfd;   // socket file descriptor for control connection
    int d_sockfd;   // socket file descriptor for data connection
    char *f_ext;    // file extension
    int d_depth;    // directory depth
    char *s_addr;   // server address
    char *l_dir;    // local directory
    char *s_dir;    // server dirctory

    char *command;    // command
    char *echoString;  // string to send to echo server
    char echo_buffer[32];     // buffer for echo string
    int bytes_received, total_bytes_received;   // bytes read in single recv(), and total bytes read


    if (argc < 5)
    {
        usage_prompt();
        exit(0);
    }


    // get input parameters
    f_ext  = (char*) (malloc(sizeof(char)*32));
    s_addr = (char*) (malloc(sizeof(char)*32));
    l_dir  = (char*) (malloc(sizeof(char)*32));
    s_dir  = (char*) (malloc(sizeof(char)*32));


    strcpy(f_ext, argv[1]);
    d_depth = 3;
    strcpy(s_addr, argv[3]);
    strcpy(l_dir, argv[4]);
    strcpy(s_dir, "/");


    if (argc > 5)
    {
        strcpy(s_dir, argv[5]);
    }


    // create control connection
    c_sockfd = create_control_connection(s_addr);

    
    command  = (char*) (malloc(sizeof(char)*32));

    strcpy(command,"USER anonymous\r\n");
    send(c_sockfd, command, strlen(command), 0);

    strcpy(command,"PASS URL\r\n");
    send(c_sockfd, command, strlen(command), 0);

    strcpy(command,"MODE S\r\n");
    send(c_sockfd, command, strlen(command), 0);

    strcpy(command,"TYPE A\r\n");
    send(c_sockfd, command, strlen(command), 0);

    // create data connection
    d_sockfd = create_data_connection(c_sockfd, s_addr, command);


    // temporary output display
    while (1)
    {
        if ((bytes_received = recv(c_sockfd, echo_buffer, 32 - 1, 0)) <= 0)
        {
            fprintf(stderr, "\nError: FTP server not available!\n");
	        exit(1);
        }
        total_bytes_received += bytes_received;
        echo_buffer[bytes_received] = '\0';
        printf(echo_buffer);
    }

    close(c_sockfd);
    exit(0);
}




int
create_control_connection(char *host_ip)
{
    int csock_fd;   // socket file descriptor
    char *server_name;
    unsigned long	server_inaddr;
    struct hostent *hp; // struct used to get address of the server
    struct sockaddr_in cli_addr, serv_addr;   // structs for client and server ip address

    // allocate memory for name of host
    server_name = (char*) (malloc(sizeof(char)*32));

    if (!server_name)
    {
	    fprintf(stderr, "\nError: Failed to allocate memory!\n");
	    exit(1);
    }

    strcpy(server_name, host_ip);

    // printf("%s\n", server_name);

    // set server details
    memset(&serv_addr, 0, sizeof(serv_addr));
	serv_addr.sin_family = AF_INET;

    // determine wheteher the host address is given as dot-notation or word-form
    if ( (server_inaddr = inet_addr(server_name)) != INADDR_NONE )
    {
        // by dot-notation
        serv_addr.sin_addr.s_addr = server_inaddr;
    }
    else
    {
        // by name
        if ( (hp = gethostbyname(server_name)) == NULL)
        {
            fprintf(stderr, "ERROR: failed to resolve host name: %s\n ", server_name);
            usage_prompt();
            exit(1);
        }
        bcopy( hp->h_addr, (char *) &serv_addr.sin_addr, hp->h_length);
    }

    serv_addr.sin_port = htons(SERV_COMMAND_PORT);


    // create the socket
    if ((csock_fd = socket(AF_INET, SOCK_STREAM, 0)) <0)
    {
	    printf("errno = %d\n", errno);
	    printf("client: can't open stream socket\n");
	    exit(1);
    }

    // connecting
    if (connect(csock_fd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
    {
	    printf("errno = %d\n", errno);
	    printf("client: can't connect host address\n");
        exit(3);
    }

    return csock_fd;
}




int
create_data_connection(int c_sockfd, char *host_ip, char *cmd)
{
    int dsock_fd, ndsock_fd;   // socket file descriptor
    int newdsock_fd;
    int serv_len;
    int cli_port;   // client port
    int cli_len;
    char *server_name;
    unsigned long	server_inaddr;
    struct hostent *hp; // struct used to get address of the server
    struct sockaddr_in cli_addr, serv_addr;   // structs for client and server ip address

    // allocate memory for name of host
    server_name = (char*) (malloc(sizeof(char)*32));

    if (!server_name)
    {
	    fprintf(stderr, "\nError: Failed to allocate memory!\n");
	    exit(1);
    }

    strcpy(server_name, host_ip);

    // printf("%s\n", server_name);

    // set server details
    memset(&serv_addr, 0, sizeof(serv_addr));
	serv_addr.sin_family = AF_INET;

    // determine wheteher the host address is given as dot-notation or word-form
    if ( (server_inaddr = inet_addr(server_name)) != INADDR_NONE )
    {
        // by dot-notation
        serv_addr.sin_addr.s_addr = server_inaddr;
    }
    else
    {
        // by name
        if ( (hp = gethostbyname(server_name)) == NULL)
        {
            fprintf(stderr, "ERROR: failed to resolve host name: %s\n ", server_name);
            usage_prompt();
            exit(1);
        }
        bcopy( hp->h_addr, (char *) &serv_addr.sin_addr, hp->h_length);
    }

    serv_addr.sin_port = htons(SERV_DATA_PORT);


    // create the socket
    if ((dsock_fd = socket(AF_INET, SOCK_STREAM, 0)) <0)
    {
	    printf("errno = %d\n", errno);
	    printf("client: can't open stream socket\n");
	    exit(1);
    }

    bzero((char *) &cli_addr, sizeof(cli_addr));


    // set client details
    cli_addr.sin_family = AF_INET;
    cli_addr.sin_addr.s_addr = htons(INADDR_ANY);
    cli_addr.sin_port = htons(0);

    // binding
    if (bind(dsock_fd, (struct sockaddr *) &cli_addr, sizeof(cli_addr)) < 0)
    {
	    printf("client: can't bind local address\n");
        exit(2);
    }

    // listening
    if (listen(dsock_fd, 10) < 0)
    {
        printf("client: can't listen to local address\n");
	    exit(3);
    }

    serv_len =  sizeof(serv_addr);
    cli_len =  sizeof(cli_addr);

    getsockname(dsock_fd, (struct sockaddr *) &cli_addr, &cli_len);

    cli_port = cli_addr.sin_port;
    // printf("%d\n", cli_port);
     
    sprintf(cmd, "PORT %d,%d,%d,%d,%d,%d\r\n",  (serv_addr.sin_addr.s_addr & 0x000000FF),
                                                (serv_addr.sin_addr.s_addr & 0x0000FF00) >> 8,
                                                (serv_addr.sin_addr.s_addr & 0x00FF0000) >> 16,
                                                (serv_addr.sin_addr.s_addr & 0xFF000000) >> 24,
                                                (cli_addr.sin_port & 0xFF00) >> 8,
                                                (cli_addr.sin_port & 0x00FF));
    
    // puts(cmd);
    send(c_sockfd, cmd, strlen(cmd), 0);

    strcpy(cmd, "LIST\r\n");
    newdsock_fd = send(c_sockfd, cmd, strlen(cmd), 0);

    // newdsock_fd = accept(dsock_fd, (struct sockaddr *) &serv_addr, &serv_len);
    
    return newdsock_fd;
}



void
usage_prompt()
{
    printf("Usage: ftpget [file extension] [directory depth] [server name] [local directory] [server directory (optional)]");
}