A minimalist telnet-like client
- From: Vinicio Flores <vfloreshdz@xxxxxxxxx>
- Date: Mon, 04 Jul 2011 18:40:56 -0600
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!!!!
PS2: That's all that I want!!!! Thank you !!!
.
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