libev example

main.c

#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <ev.h>
#include <strings.h>

#define PORT_NO 3033
#define BUFFER_SIZE 1024

void accept_cb(struct ev_loop *loop, struct ev_io *watcher, int revents);
void read_cb(struct ev_loop *loop, struct ev_io *watcher, int revents);

int main()
{
  struct ev_loop *loop = ev_default_loop(0);
  int sd;
  struct sockaddr_in addr;
  int addr_len = sizeof(addr);
  struct ev_io w_accept;

  // Create server socket
  if( (sd = socket(PF_INET, SOCK_STREAM, 0)) < 0 )
  {
    perror("socket error");
    return -1;
  }

  bzero(&addr, sizeof(addr));
  addr.sin_family = AF_INET;
  addr.sin_port = htons(PORT_NO);
  addr.sin_addr.s_addr = INADDR_ANY;

  // Bind socket to address
  if (bind(sd, (struct sockaddr*) &addr, sizeof(addr)) != 0)
  {
    perror("bind error");
  }

  // Start listing on the socket
  if (listen(sd, 2) < 0)
  {
    perror("listen error");
    return -1;
  }

  // Initialize and start a watcher to accepts client requests
  ev_io_init(&w_accept, accept_cb, sd, EV_READ);
  ev_io_start(loop, &w_accept);

  // Start infinite loop
  while (1)
  {
    ev_loop(loop, 0);
  }

  return 0;
}

void accept_cb(struct ev_loop *loop, struct ev_io *watcher, int revents)
{
  struct sockaddr_in client_addr;
  socklen_t client_len = sizeof(client_addr);
  int client_sd;
  struct ev_io *w_client = (struct ev_io*) malloc (sizeof(struct ev_io));

  if(EV_ERROR & revents)
  {
    perror("got invalid event");
    return;
  }

  // Accept client request
  client_sd = accept(watcher->fd, (struct sockaddr *)&client_addr, &client_len);

  if (client_sd < 0)
  {
    perror("accept error");
    return;
  }

  // Initialize and start watcher to read client requests
  ev_io_init(w_client, read_cb, client_sd, EV_READ);
  ev_io_start(loop, w_client);
}

/* Read client message */
void read_cb(struct ev_loop *loop, struct ev_io *watcher, int revents){
  char buffer[BUFFER_SIZE];
  ssize_t read;

  if(EV_ERROR & revents)
  {
    perror("got invalid event");
    return;
  }

  // Receive message from client socket
  read = recv(watcher->fd, buffer, BUFFER_SIZE, 0);

  if(read < 0)
  {
    perror("read error");
    return;
  }

  if(read == 0)
  {
    // Stop and free watchet if client socket is closing
    ev_io_stop(loop,watcher);
    free(watcher);
    perror("peer might closing");
    return;
  }
  else
  {
    printf("message:%s",buffer);
  }

  // Send message bach to the client
  /* send(watcher->fd, buffer, read, 0); */
  bzero(buffer, read);
}