Ecore_Con - DNS lookup

This is a very simple example that shows how to make a simple DNS lookup using ecore_con_lookup().

It's possible to see in the beginning of the main function that we are using the arguments passed via command line. This is the address that we are going to make the DNS lookup on.

The next step is to initialize the libraries, and just call ecore_con_lookup(). This function will get the string that contains the address to be resolved as first parameter, then a callback that will be called when the resolve stage is done, and finally a data pointer that will be passed to the callback.

This function is asynchronous, and the callback will be called only on success. If there was an error during the resolve stage, there's no way to know about that. It's only possible to know about errors when setting up the lookup, by looking at the return code of the ecore_con_lookup() function.

The callback _lookup_done_cb passed as argument to ecore_con_lookup() just prints the resolved canonical name, IP, address of the sockaddr structure, and the length of the socket address (in bytes).

Finally, we start the main loop, and after that we finalize the libraries and exit.

This is the code for this simple example:

//Compile with:
// gcc -o ecore_con_lookup_example ecore_con_lookup_example.c `pkg-config --libs --cflags ecore ecore-con`
 
#include <stdio.h>
#include <Ecore.h>
#include <Ecore_Con.h>
 
static void
_lookup_done_cb(const char *canonname, const char *ip, struct sockaddr *addr, int addrlen EINA_UNUSED, void *data EINA_UNUSED)
{
   printf("canonname = %s\n", canonname);
   printf("ip = %s\n", ip);
   printf("addr = %p\n", addr);
   ecore_main_loop_quit();
}
 
int
main(int argc, const char *argv[])
{
   if (argc < 2)
     {
        printf("need one parameter: <address>\n");
        return -1;
     }
 
   ecore_con_init();
 
   if (!ecore_con_lookup(argv[1], _lookup_done_cb, NULL))
     {
        printf("error when trying to start lookup for %s\n", argv[1]);
        goto end;
     }
 
   ecore_main_loop_begin();
 
end:
   ecore_con_shutdown();
 
   return 0;
}