Mini Servidor em C

Este é um exemplo de código para um servidor mínimo, que lê um byte (letra) e envia outro byte (letra S) pela internet. As tarefas para se conseguir isso são realizadas na ordem:

1. Configuring environment... done!
2. Creating socket... done!
3. Configuring socket... done!
4. Binding... done!
5. Listening... done!
6. Accepting... done!
7. Reading... "C"done!
8. Writing "S"... done!

Abaixo o código:

/*
Program: minser.c
Author: Dr Beco
Date: 2001-04-03
Objective:
 show a minimum server program that can
 create a socket, accept a client, read a byte, write a byte, disconnect
*/

#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/un.h>

#define BUFFER 2

int main(void)
{
 printf("Configuring environment... ");

 int p = 3333; // port
 char data[BUFFER];
 struct sockaddr_in dir;
   struct sockaddr client;
   socklen_t long_client;
   int id, idReuse=1, son, aux;

   memset(&dir,0,sizeof(dir));
   dir.sin_port = p;
   dir.sin_family = AF_INET;
   dir.sin_addr.s_addr = INADDR_ANY;
 printf("done!\n");

   printf("Creating socket... ");
   id = socket(AF_INET, SOCK_STREAM, 0);
   if (id == -1)
  return -1;
 printf("done!\n");

 printf("Configuring socket... ");
 if(setsockopt(id,SOL_SOCKET,SO_REUSEADDR,&idReuse,sizeof(idReuse))==-1)
      return -1;
 printf("done!\n");

 printf("Binding... ");
   if(bind(id, (struct sockaddr *)&dir, sizeof(dir)) == -1)
   {
       close (id);
       return -1;
   }
 printf("done!\n");

 printf("Listening... ");
   if (listen(id , 1) == -1)
   {
       close(id);
       return -1;
   }
 printf("done!\n");

 printf("Accepting... ");
   long_client = sizeof (client);
   son = accept(id, &client, &long_client);
 if (son == -1)
  return -1;
 printf("done!\n");

 printf("Reading... ");
 aux = read(son, data , 1);
 if(aux!=1)
  return -1;
 printf("\"%c\" ", data[0]);
 printf("done!\n");

 printf("Writing \"S\"... ");
 aux = send(son, "S", 1, MSG_NOSIGNAL);
 if(aux < 0)
  return -1;
 printf("done!\n");

 return 0;
}