#include #include #include #include #include #include #define UNUSED_PARAM(x) ((void)(x)) /* Set up the callback function, which will also do the processing of the results */ void this_callbackfn(struct getdns_context *this_context, getdns_callback_type_t this_callback_type, struct 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; } struct 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 ) { struct 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 */ struct 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 */ struct 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); }