mirror of https://github.com/getdnsapi/getdns.git
206 lines
7.0 KiB
C
206 lines
7.0 KiB
C
/**
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*
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* \file example-simple-answers.c
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* @brief example using getdns to resolve a simple query
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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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*/
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/*
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* Copyright (c) 2013, Versign, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the <organization> nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL Verisign, Inc. BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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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 *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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getdns_return_t this_ret;
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uint32_t this_error;
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size_t num_addresses;
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struct getdns_list *just_the_addresses_ptr;
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struct getdns_dict *this_address;
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struct getdns_bindata *this_address_data;
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size_t rec_count;
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char *this_address_str;
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UNUSED_PARAM(this_userarg);
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UNUSED_PARAM(this_context);
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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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this_ret = getdns_dict_get_int(this_response, "status", &this_error);
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if (this_ret != GETDNS_RETURN_GOOD)
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{
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fprintf(stderr, "The dictionary does not contain \"status\" (this shouldn't have happened). Exiting\n");
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getdns_dict_destroy(this_response);
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return;
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}
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if (this_error != GETDNS_RESPSTATUS_GOOD)
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{
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fprintf(stderr, "The search had no results, and a return value of %d. Exiting.\n", this_error);
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getdns_dict_destroy(this_response);
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return;
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}
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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)
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{
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fprintf(stderr, "The dict does not contain \"just_address_answers\" (this shouldn't have happened), and returned %d. Exiting.\n", this_ret);
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getdns_dict_destroy(this_response);
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return;
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}
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this_ret = getdns_list_get_length(just_the_addresses_ptr, &num_addresses);
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if (this_ret != GETDNS_RETURN_GOOD)
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{
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fprintf(stderr, "The address list is invalid (this shouldn't have happened). Exiting\n");
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getdns_dict_destroy(this_response);
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return;
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}
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if (num_addresses == 0)
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fprintf(stderr, "The address list has 0 records. Exiting\n");
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/* Go through each record */
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for (rec_count = 0; rec_count < num_addresses; ++rec_count)
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{
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this_ret = getdns_list_get_dict(just_the_addresses_ptr, rec_count, &this_address);
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if(this_ret != GETDNS_RETURN_GOOD)
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{
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fprintf(stderr, "Record %d is invalid (this shouldn't have happened). skipping.\n", (int) rec_count);
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continue;
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}
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/* Just print the address */
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this_ret = getdns_dict_get_bindata(this_address, "address_data", &this_address_data);
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if(this_ret != GETDNS_RETURN_GOOD)
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{
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fprintf(stderr, "Record %d does not contain \"address_data\" (this shouldn't happen), skipping\n", (int) rec_count);
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}
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else
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{
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this_address_str = getdns_display_ip_address(this_address_data);
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printf("The address is %s\n", this_address_str);
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free(this_address_str);
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}
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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.\n", this_transaction_id);
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else
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fprintf(stderr, "The callback got a callback_type of %d. Exiting.\n", this_callback_type);
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getdns_dict_destroy(this_response);
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} /* this_callbackfn */
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/*---------------------------------------- main */
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int
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main(int argc, char *argv[])
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{
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char *this_name = "www.example.com";
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char *this_userarg = "somestring";
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int dispatch_return;
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int exitval = EXIT_SUCCESS;
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struct getdns_context *this_context = NULL;
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struct event_base *this_event_base;
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getdns_return_t dns_request_return;
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getdns_transaction_t this_transaction_id;
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getdns_return_t context_create_return;
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if(argc > 1)
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this_name = argv[1];
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printf("resolving %s\n", this_name);
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/* Create the DNS context for this call, use OS configs such as resolv.conf */
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context_create_return = getdns_context_create(&this_context, 1);
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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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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.\n");
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getdns_context_destroy(this_context);
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return(GETDNS_RETURN_GENERIC_ERROR);
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}
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getdns_extension_set_libevent_base(this_context, this_event_base);
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/* Set up the getdns call */
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this_transaction_id = 0;
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/* Make the call */
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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.\n", this_name);
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exitval = 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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dispatch_return = event_base_dispatch(this_event_base);
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if(dispatch_return < 0)
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fprintf(stderr, "event_base_dispatch() failed, returned %d\n", dispatch_return);
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}
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/* Clean up */
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event_base_free(this_event_base);
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getdns_context_destroy(this_context);
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return exitval;
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} /* main */
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/* example-simple-answers.c */
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