🚀 go-pugleaf

Can you tell me what I have to know if I want to write a FTP Client??
And can you tell me how can I do it??

And if you have a good UNIX sockets howto to give, please give me 
one!!!!

I am working under GNU/Linux , I want to implement it using Sockets
Thank you!!!

Here I put the files:

/** MAIN FILE  -- cnet.c **/

/* 
 * A simple client to open connection
 * to servers and comunicate with
 * them.
 */

#ifndef _CNET_H
#include "cnet.h"
#endif

int main(argc, argv)
     int argc;
     char **argv;
{
  // If the user no input the needed
  // arguments
  if(argc != 3)
    handle_err(NEED_ARGC);

  // The struct where I will
  // save the socket 
  // connection data
  struct sock_client *sock = malloc ( sizeof(struct sock_client));
  // The client address struct
  struct sockaddr_in serv_addr;
  // Information about the server
  struct hostent *server;

  // The read and write streams
  // to FTP server
  FILE *cout, *cin;

  Buffer cbuff;

  // The message that
  // I will send
  String sended = "Hello World, I am connected to this server\n\r";

  // Convert the third argument 
  // to an integer number to
  // get the port number
  sock->n_port = atoi( *(argv + 2) );

  // Creates socket
  sock->sockfd = socket(AF_INET, SOCK_STREAM, 0);

  // Check if the creation of socket fails or is done...
  if(sock->sockfd == SYS_ERR)
    handle_err(OPENSOCK_ERR);

  // Initializes structs to zero
  memset(&serv_addr, 0, sizeof(serv_addr));

  // Get the host by its name
  server = gethostbyname( *(argv + 1) );

  // If cannot resolve host ...
  if(!server) 			// You can do a server == 
NULL but is more beauty to use !server and the GCC won't cry
    handle_err(GETHOST_ERR);

  // Fill the server address struct
  serv_addr.sin_addr = *((struct in_addr *)server->h_addr );
  serv_addr.sin_family = AF_INET;
  serv_addr.sin_port = htons(sock->n_port);

  // The server address length
  sock->addrlen = sizeof(serv_addr);

  // Get the remote ip address
  sock->ip = inet_ntoa(serv_addr.sin_addr);

  // Print the IP Address
  setcolor(FOREBLUE);
  cprintf("IP Address: ");

  setattr(BOLD);
  setcolor(FOREGREEN);

  cprintf("%s\033[0m\n", sock->ip);

  // Connect to the server and check if connect fails 
  if( (sock->con = connect(sock->sockfd, (struct sockaddr *)&serv_addr, 
sock->addrlen) ) == SYS_ERR)
    handle_err(CONNECT_ERR);

  /* Send a message to the server, this is so
   * trivial, only for funny!!! :-)
   */
  sock->bytes_wrote = write(sock->sockfd, sended, strlen(sended));

  // If cannot send message
  if(sock->bytes_wrote == SYS_ERR)
    handle_err(WRITE_ERR);

   // Read data from server
  sock->bytes_read = recv(sock->sockfd, sock->buffer, MAX_SIZE, 0);

  // If read fails ...
  if(sock->bytes_read == SYS_ERR)
    handle_err(READ_ERR);

  sock->buffer[sock->bytes_read] == '\0';
  // Print the server welcome message
  write(STDOUT_FILENO, sock->buffer, MAX_SIZE);

  cin = fdopen(sock->sockfd, "r");

  fgets(cbuff, MAX_SIZE, cin);
  fputs(cbuff, stdout);

  // Ask for USER
  setattr(BOLD);
  setcolor(FOREYELLOW);
  cprintf("USER: ");
  setattr(NORMAL);
  setattr(BOLD);
  fgets(sock->user, MAX_SIZE, stdin);

  // Ask for Password
  setattr(BOLD);
  setcolor(FOREYELLOW);
  cprintf("PASS: ");
  setattr(NORMAL);
  setattr(BOLD);
  fgets(sock->pass, MAX_SIZE, stdin);

  // Send USER to FTP server
  send(sock->sockfd, sock->user, MAX_SIZE, 0);
  // Send PASS to FTP Server
  send(sock->sockfd, sock->pass, MAX_SIZE, 0);

  // Close socket
  close(sock->sockfd);

  // Set the original terminal's status
  setattr(NORMAL);
  normvideo();

  return 0;
}


/** cnet.h -- global header **/

/* A simple client to open connection                                          
 * to servers and comunicate with them, 
 * like telnet.                                                                 
 */

#ifndef _CNET_H
#define _CNET_H

#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>

#ifndef _TTK_H
#include <ttk.h>
#endif

#define VERSION         0.2
#define COPYLEFT        "\nCopyleft (C) Vinicio Flores\nAll rights 
reversed\n\rThis program is free software, it is licensed under the GNU 
GPL\n\rRead LICENSE for more information\n\r"
#define CRAP            "\nYou can do with it all that you want, join 
us and share the software\n"

/* The max size of a memory buffer */

#define MAX_SIZE       800

#define SYS_ERR       -1    // The error value that an UNIX system call 
returns

// Boolean types and other data types
typedef enum  { false, true } bool;

typedef char *String;
typedef char Buffer[MAX_SIZE];

typedef unsigned char byte;
typedef unsigned char octet;
typedef unsigned short word;
typedef unsigned int dword;

/* Some error values 
 * of diferent system calls
 */

#define NEED_ARGC      0x00
#define OPENSOCK_ERR   0x01 
#define CONNECT_ERR    0x02
#define GETHOST_ERR    0x03
#define READ_ERR       0x04
#define WRITE_ERR      0x05


struct sock_client
{
  int sockfd;
  int bytes_read, bytes_wrote;
  int con;
  int n_port;
  Buffer buffer;
  socklen_t addrlen;
  String ip;
  Buffer user, pass;
};

/* Routines to handle errors */

extern void handle_err(int);

#endif // _CNET_H


/** Some routines used by cnet **/

/* Some routines used by cnet */

#ifndef _CNET_H
#include "cnet.h"
#endif

/* Handle and process common errors */
void handle_err(int n_error)
{
  switch(n_error)
    {
    case OPENSOCK_ERR:
      perror("Error while opening socket");
      exit(OPENSOCK_ERR);
      break;
    case CONNECT_ERR:
      perror("Error while trying to connect to server");
      exit(CONNECT_ERR);    
      break;
    case NEED_ARGC:
      reset();
      setattr(REVERSE);
      setcolor(FORERED);
      cprintf("Cnet v%3.1f\n", VERSION);
      setattr(NORMAL);
      setattr(BOLD);
      setcolor(FORECYAN);
      cprintf("Usage: ");
      setattr(NORMAL);
      cprintf("cnet <hostname> <n_port> Example(");
      setattr(UNDERLINE);
      cprintf("cnet ftp.gnu.org 21");
      setattr(NORMAL);
      cprintf(")\n");
      normvideo();

      setattr(BOLD|REVERSE);
      cprintf("\nAbout Cnet \n");

      setattr(NORMAL);

      cprintf("\t\tCnet is a terminal-based program that connects to a 
server, like Telnet\n\r");
      cprintf("\t\tCnet aims to be an enhanced and minimalistic telnet 
program\n\r");
      cprintf("\t\tThis is an alpha release and maybe it will not work 
properly, please download the cnet source code and work on it\n\r");
      cprintf("%s%s\n\r", COPYLEFT, CRAP);

      exit(NEED_ARGC);
      break;
    case GETHOST_ERR:
      setcolor(FORERED);
      cprintf("Error, no such host\n");
      setattr(NORMAL);
      normvideo();
      exit(GETHOST_ERR);
      break;
    case READ_ERR:
      perror("Read error");
      setattr(NORMAL);
      normvideo();
      exit(READ_ERR);
      break;
    case WRITE_ERR:
      perror("Write error");
      exit(WRITE_ERR);
      break;
    }
}

// And here is the Makefile

# Makefile for cnet

CFLAGS=-O -O2 -O3 -g -Wall -lttk -DMONOLITH -fwhole-program -Ofast -
fcommon -Werror

BINARY=cnet
CC=gcc

all:
	$(CC) -c *.c
	$(CC) -o $(BINARY) *.o $(CFLAGS)

clean:
	rm *.o $(BINARY)

install:
	cp cnet /usr/bin

PS: Please tell me what can I do more here!!!!