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;
}