getdns/spec/example/example-simple-answers.c

109 lines
4.3 KiB
C

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <getdns_libevent.h>
#define UNUSED_PARAM(x) ((void)(x))
/* Set up the callback function, which will also do the processing of the results */
void this_callbackfn(getdns_context *this_context,
getdns_callback_type_t this_callback_type,
getdns_dict *this_response,
void *this_userarg,
getdns_transaction_t this_transaction_id)
{
UNUSED_PARAM(this_userarg); /* Not looking at the userarg for this example */
UNUSED_PARAM(this_context); /* Not looking at the context for this example */
getdns_return_t this_ret; /* Holder for all function returns */
if (this_callback_type == GETDNS_CALLBACK_COMPLETE) /* This is a callback with data */
{
/* Be sure the search returned something */
uint32_t this_error;
this_ret = getdns_dict_get_int(this_response, "status", &this_error); // Ignore any error
if (this_error != GETDNS_RESPSTATUS_GOOD) // If the search didn't return "good"
{
fprintf(stderr, "The search had no results, and a return value of %d. Exiting.\n", this_error);
getdns_dict_destroy(this_response);
return;
}
getdns_list * just_the_addresses_ptr;
this_ret = getdns_dict_get_list(this_response, "just_address_answers", &just_the_addresses_ptr);
if (this_ret != GETDNS_RETURN_GOOD) // This check is really not needed, but prevents a compiler error under "pedantic"
{
fprintf(stderr, "Trying to get the answers failed: %d\n", this_ret);
getdns_dict_destroy(this_response);
return;
}
size_t num_addresses;
this_ret = getdns_list_get_length(just_the_addresses_ptr, &num_addresses); // Ignore any error
/* Go through each record */
for ( size_t rec_count = 0; rec_count < num_addresses; ++rec_count )
{
getdns_dict * this_address;
this_ret = getdns_list_get_dict(just_the_addresses_ptr, rec_count, &this_address); // Ignore any error
/* Just print the address */
getdns_bindata * this_address_data;
this_ret = getdns_dict_get_bindata(this_address, "address_data", &this_address_data); // Ignore any error
char *this_address_str = getdns_display_ip_address(this_address_data);
printf("The address is %s\n", this_address_str);
free(this_address_str);
}
}
else if (this_callback_type == GETDNS_CALLBACK_CANCEL)
fprintf(stderr, "The callback with ID %"PRIu64" was cancelled. Exiting.\n", this_transaction_id);
else
fprintf(stderr, "The callback got a callback_type of %d. Exiting.\n", this_callback_type);
getdns_dict_destroy(this_response);
}
int main()
{
/* Create the DNS context for this call */
getdns_context *this_context = NULL;
getdns_return_t context_create_return = getdns_context_create(&this_context, 1);
if (context_create_return != GETDNS_RETURN_GOOD)
{
fprintf(stderr, "Trying to create the context failed: %d", context_create_return);
return(GETDNS_RETURN_GENERIC_ERROR);
}
/* Create an event base and put it in the context using the unknown function name */
struct event_base *this_event_base;
this_event_base = event_base_new();
if (this_event_base == NULL)
{
fprintf(stderr, "Trying to create the event base failed.\n");
getdns_context_destroy(this_context);
return(GETDNS_RETURN_GENERIC_ERROR);
}
(void)getdns_extension_set_libevent_base(this_context, this_event_base);
/* Set up the getdns call */
const char * this_name = "www.example.com";
char* this_userarg = "somestring"; // Could add things here to help identify this call
getdns_transaction_t this_transaction_id = 0;
/* Make the call */
getdns_return_t dns_request_return = getdns_address(this_context, this_name,
NULL, this_userarg, &this_transaction_id, this_callbackfn);
if (dns_request_return == GETDNS_RETURN_BAD_DOMAIN_NAME)
{
fprintf(stderr, "A bad domain name was used: %s. Exiting.\n", this_name);
event_base_free(this_event_base);
getdns_context_destroy(this_context);
return(GETDNS_RETURN_GENERIC_ERROR);
}
else
{
/* Call the event loop */
int dispatch_return = event_base_dispatch(this_event_base);
UNUSED_PARAM(dispatch_return);
// TODO: check the return value above
}
/* Clean up */
event_base_free(this_event_base);
getdns_context_destroy(this_context);
/* Assuming we get here, leave gracefully */
exit(EXIT_SUCCESS);
}