We use `g_socket_new` to open a socket and create a `GIOChannel` objct.
```c
#include <gio/gio.h>
#include <glib.h>

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define BLOCK_SIZE 1024

#define GG g_print("line %d\n",__LINE__)

static gboolean
gio_read_socket (GIOChannel     *channel,
                 GIOCondition    condition,
                 gpointer        data)
{
    static int r = 0;
    r++;
    printf("r=%d\n",r);

    char buf[1024];
    gsize bytes_read;
    GError *error = NULL;
    g_print("gio_read_socket\n");

    if (condition & G_IO_HUP) return FALSE; /* this channel is done */
    GG;
    g_print("channel not done\n");

    // g_io_channel_read (channel, buf, sizeof (buf), &bytes_read);
    g_io_channel_read_chars (channel, buf, sizeof (buf), &bytes_read, &error);
    g_print("g_io_channel_read_chars\n");
    g_print("%ld bytes read\n",bytes_read);
    
    g_assert (error == NULL);


    GG;
    buf[bytes_read] = '\0';

    g_print ("%s", buf);
    int i=0,l=32;
    for(int i=0; i<bytes_read && i<sizeof(buf); i++) {
      printf("%02x ",buf[i]);
      if( (i+1) % l == 0 ) {
        printf("\n");
      }
    }
    if( (i % l) != 0 ) {
      printf("\n");
    }

    int *a = data;
    *a = *a + 1;

    return TRUE;
}

gboolean
idleCpt (gpointer user_data){

   int *a = user_data;
   g_print("hello\n");
   g_print("%d\n", *a);
   usleep(10000);

   return TRUE;
}
int
main (int argc, char **argv)
{

  GSocket * s_udp;
  GError *err = NULL;
  int idIdle = -1, dataI = 0;
  guint16 udp_port = 4001;
  GSocketAddress * gsockAddr = G_SOCKET_ADDRESS(g_inet_socket_address_new(g_inet_address_new_any(G_SOCKET_FAMILY_IPV4), udp_port));
  s_udp = g_socket_new(G_SOCKET_FAMILY_IPV4,
                    G_SOCKET_TYPE_DATAGRAM,
                    G_SOCKET_PROTOCOL_UDP,
                    &err);
  g_assert(err == NULL);

  if (s_udp == NULL) {
    g_print("ERREUR");
    exit(1);
  }


  if (g_socket_bind (s_udp, gsockAddr, TRUE, NULL) == FALSE){

   g_print("Erreur bind\n");
   exit(1);

  }

  g_assert(err == NULL);

  int fd = g_socket_get_fd(s_udp);

  GIOChannel* channel = g_io_channel_unix_new(fd);
  g_io_channel_set_encoding ( channel, NULL , &err );

  g_assert(err == NULL);

  guint source = g_io_add_watch(channel, G_IO_IN,
                              (GIOFunc) gio_read_socket, &dataI);

  g_io_channel_unref(channel);


   GMainLoop *loop = g_main_loop_new(NULL, FALSE);
   idIdle = g_idle_add(idleCpt, &dataI);
   g_main_loop_run(loop);
}
```