In this article I'll show you the code for the tcp client for the echo server.
/*+————————————————————–+
| tcp.client.c – description |
| ——————- |
| begin : 05/08/2010 20.00 |
| copyright : (C) 2010 xAppSoftware |
| author : Luigi D'Andrea |
| email : gg1 ( at ) xappsoftware dot com |
| compiling : gcc -o tcp.client tcp.client.c |
| |
| Latest version on http://www.xappsoftware.com |
+————————————————————–+
| udp client-server may be redistributed and modified under |
| certain conditions. This software is distributed on an |
| "AS IS" basis WITHOUT WARRANTY OF ANY KIND, either express or|
| implied. See the file License.txt for details. |
+————————————————————–+*/
/*+————————————————————–+
| SYSTEM INCLUDES |
+————————————————————–+*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
/*+————————————————————–+
| PROTOTYPES |
+————————————————————–+*/
int main(int argc, char **argv);
void Usage(char **argv);
Blablablabla.
Finally the main function…..
/*+————————————————————–+
| Function name : main |
| Parameters : The destination IP address |
| The port number |
| Description : The simple TCP echo client |
+————————————————————–+*/
int main(int argc, char **argv)
{
int clnt_fd;
struct sockaddr_in serv_addr;
char c;
First of all I check for the command line arguments, the client shall know the port on which it send data and the IP address of the system on which the server is running.
{
Usage(argv);
exit(EXIT_FAILURE);
}
I create a socket, if the socket() call fails then the program exits.
// create socket
clnt_fd = socket(AF_INET, SOCK_STREAM, 0);
if(clnt_fd==-1)
{
perror("Error while opening socket");
exit(EXIT_FAILURE);
}
Preparing the server address where I want to send data.
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(atoi(argv[2]));
serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
I'm trying to connect to the server.
// connect to echo server
connect(clnt_fd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
The following lines read data from the keyboard and after a "return" send them to the server, then the clients waits for the echo.
while ((c = (char) getchar()) != EOF) // read from keyboard
{
write(clnt_fd, &c, 1); // write to echo server
read(clnt_fd, &c, 1); // read from echo server
putchar((int) c); // write to monitor
}
Release the socket and exit.
return 0;
}
void Usage(char **argv)
{
printf("Usage: %s <dest_ip_address> <port_number>\n", argv[0]);
return;
}