mirror of https://github.com/getdnsapi/getdns.git
131 lines
5.3 KiB
C
131 lines
5.3 KiB
C
/**
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* /brief demonstrate asynchronous use of the API for fetching DNS data
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*
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* Originally taken from the getdns API description pseudo implementation.
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*/
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/* The MIT License (MIT)
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* Copyright (c) 2013 Verisign, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <inttypes.h>
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#include <getdns_libevent.h>
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#define UNUSED_PARAM(x) ((void)(x))
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/* Set up the callback function, which will also do the processing of the results */
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void this_callbackfn(struct getdns_context_t *this_context,
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uint16_t this_callback_type,
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struct getdns_dict *this_response,
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void *this_userarg,
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getdns_transaction_t this_transaction_id)
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{
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UNUSED_PARAM(this_userarg); /* Not looking at the userarg for this example */
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UNUSED_PARAM(this_context); /* Not looking at the context for this example */
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getdns_return_t this_ret; /* Holder for all function returns */
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if (this_callback_type == GETDNS_CALLBACK_COMPLETE) /* This is a callback with data */
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{
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/* Be sure the search returned something */
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uint32_t * this_error = NULL;
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this_ret = getdns_dict_get_int(this_response, "status", this_error); // Ignore any error
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if (*this_error != GETDNS_RESPSTATUS_GOOD) // If the search didn't return "good"
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{
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fprintf(stderr, "The search had no results, and a return value of %d. Exiting.", *this_error);
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return;
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}
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struct getdns_list * just_the_addresses_ptr;
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this_ret = getdns_dict_get_list(this_response, "just_address_answers", &just_the_addresses_ptr);
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if (this_ret != GETDNS_RETURN_GOOD) // This check is really not needed, but prevents a compiler error under "pedantic"
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{
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fprintf(stderr, "Trying to get the answers failed: %d", this_ret);
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return;
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}
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size_t * num_addresses_ptr = NULL;
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this_ret = getdns_list_get_length(just_the_addresses_ptr, num_addresses_ptr); // Ignore any error
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/* Go through each record */
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for ( size_t rec_count = 0; rec_count <= *num_addresses_ptr; ++rec_count )
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{
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struct getdns_dict * this_address;
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this_ret = getdns_list_get_dict(just_the_addresses_ptr, rec_count, &this_address); // Ignore any error
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/* Just print the address */
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struct getdns_bindata * this_address_data;
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this_ret = getdns_dict_get_bindata(this_address, "address_data", &this_address_data); // Ignore any error
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printf("The address is %s", getdns_display_ip_address(this_address_data));
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}
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}
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else if (this_callback_type == GETDNS_CALLBACK_CANCEL)
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fprintf(stderr, "The callback with ID %"PRIu64" was cancelled. Exiting.", this_transaction_id);
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else
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fprintf(stderr, "The callback got a callback_type of %d. Exiting.", this_callback_type);
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}
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int
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main()
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{
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/* Create the DNS context for this call */
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struct getdns_context_t *this_context = NULL;
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getdns_return_t context_create_return = getdns_context_create(&this_context, true);
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if (context_create_return != GETDNS_RETURN_GOOD)
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{
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fprintf(stderr, "Trying to create the context failed: %d", context_create_return);
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return(GETDNS_RETURN_GENERIC_ERROR);
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}
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/* Create an event base and put it in the context using the unknown function name */
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struct event_base *this_event_base;
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this_event_base = event_base_new();
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if (this_event_base == NULL)
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{
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fprintf(stderr, "Trying to create the event base failed.");
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return(GETDNS_RETURN_GENERIC_ERROR);
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}
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(void)getdns_extension_set_libevent_base(this_context, this_event_base);
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/* Set up the getdns call */
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const char * this_name = "www.example.com";
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char* this_userarg = "somestring"; // Could add things here to help identify this call
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getdns_transaction_t this_transaction_id = 0;
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/* Make the call */
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getdns_return_t dns_request_return = getdns_address(this_context, this_name,
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NULL, this_userarg, &this_transaction_id, this_callbackfn);
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if (dns_request_return == GETDNS_RETURN_BAD_DOMAIN_NAME)
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{
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fprintf(stderr, "A bad domain name was used: %s. Exiting.", this_name);
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return(GETDNS_RETURN_GENERIC_ERROR);
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}
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else
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{
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/* Call the event loop */
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int dispatch_return = event_base_dispatch(this_event_base);
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UNUSED_PARAM(dispatch_return);
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// TODO: check the return value above
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}
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/* Clean up */
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getdns_context_destroy(this_context);
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/* Assuming we get here, leave gracefully */
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exit(EXIT_SUCCESS);
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} /* main */
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/* example-simple-answers.c */
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