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/*
* Code in examine_result() is taken from official libunbound examples:
* https://nlnetlabs.nl/documentation/unbound/libunbound-tutorial-3/
* The rest of this file is
* Copyright (C) 2020 by Wojtek Kosior <echo a3dvanR1c0Bwcm90b25tYWlsLmNvbQo= | base64 --decode>
* Permission to use, copy, modify, and/or distribute this software
* for any purpose with or without fee is hereby granted.
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is a simple helper program for testing our resolver.
*/
#include <stdio.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unbound.h>
/* examine the result structure in detail */
void examine_result(const char *query, struct ub_result *result)
{
int i;
int num;
printf("The query is for: %s\n", query);
printf("The result has:\n");
printf("qname: %s\n", result->qname);
printf("qtype: %d\n", result->qtype);
printf("qclass: %d\n", result->qclass);
if(result->canonname)
printf("canonical name: %s\n",
result->canonname);
else printf("canonical name: <none>\n");
if(result->havedata)
printf("has data\n");
else printf("has no data\n");
if(result->nxdomain)
printf("nxdomain (name does not exist)\n");
else printf("not an nxdomain (name exists)\n");
if(result->secure)
printf("validated to be secure\n");
else printf("not validated as secure\n");
if(result->bogus)
printf("a security failure! (bogus)\n");
else printf("not a security failure (not bogus)\n");
printf("DNS rcode: %d\n", result->rcode);
if(!result->havedata)
return;
num = 0;
for(i=0; result->data[i]; i++) {
printf("result data element %d has length %d\n",
i, result->len[i]);
printf("result data element %d is: %s\n",
i, inet_ntoa(*(struct in_addr*)result->data[i]));
num++;
}
printf("result has %d data element(s)\n", num);
}
struct ub_ctx *create_ub_context(char *forwarder_addr, int debuglevel)
{
int rc;
struct ub_ctx* ctx;
char *error_message_format;
ctx = ub_ctx_create();
if (!ctx) {
fprintf(stderr, "Couldn't create libunbound context.\n");
return NULL;
}
error_message_format = "Couldn't set forwarder: %s\n";
rc = ub_ctx_set_fwd(ctx, forwarder_addr);
if (rc)
goto out;
error_message_format = "Couldn't set debuglevel: %s\n";
rc = ub_ctx_debuglevel(ctx, debuglevel);
out:
if (rc) {
fprintf(stderr, error_message_format, ub_strerror(rc));
ub_ctx_delete(ctx);
return NULL;
}
return ctx;
}
void ztdns_try_resolve(struct ub_ctx *ctx, const char *name)
{
struct ub_result* result;
int rc;
rc = ub_resolve(ctx, name,
1 /* TYPE A (IPv4 address) */,
1 /* CLASS IN (internet) */, &result);
if(rc)
printf("resolve error: %s\n", ub_strerror(rc));
else {
examine_result(name, result);
ub_resolve_free(result);
}
}
int main(int argc, char** argv)
{
struct ub_ctx *ctx;
if (argc != 3) {
printf("Usage: %s DNS_SERVER DOMAINNAME\n", argv[0]);
return EXIT_FAILURE;
}
ctx = create_ub_context(argv[1], 3);
if (!ctx)
return EXIT_FAILURE;
ztdns_try_resolve(ctx, argv[2]);
ub_ctx_delete(ctx);
return EXIT_SUCCESS;
}
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