ldns-mx.c

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/*
 * mx is a small program that prints out the mx records
 * for a particular domain
 * (c) NLnet Labs, 2005 - 2008
 * See the file LICENSE for the license
 */
 
#include "config.h"
 
#include <ldns/ldns.h>
 
static int
usage(FILE *fp, char *prog) {
        fprintf(fp, "%s domain\n", prog);
        fprintf(fp, "  print out the mx for domain\n");
        return 0;
}
 
int
main(int argc, char *argv[])
{
        ldns_resolver *res;
        ldns_rdf *domain;
        ldns_pkt *p;
        ldns_rr_list *mx;
        ldns_status s;
        
        p = NULL;
        mx = NULL;
        domain = NULL;
        res = NULL;
        
        if (argc != 2) {
                usage(stdout, argv[0]);
                exit(EXIT_FAILURE);
        } else {
                /* create a rdf from the command line arg */
                domain = ldns_dname_new_frm_str(argv[1]);
                if (!domain) {
                        usage(stdout, argv[0]);
                        exit(EXIT_FAILURE);
                }
                if (! ldns_dname_str_absolute(argv[1]) &&
                    ldns_dname_absolute(domain)) {
 
                        /* ldns_dname_new_frm_str makes absolute dnames always!
                         * So deabsolutify domain.
                         * TODO: Create ldns_dname_new_frm_str_relative? Yuck!
                         */
                        ldns_rdf_set_size(domain, ldns_rdf_size(domain) - 1);
                }
        }
 
        /* create a new resolver from /etc/resolv.conf */
        s = ldns_resolver_new_frm_file(&res, NULL);
 
        if (s != LDNS_STATUS_OK) {
                exit(EXIT_FAILURE);
        }
 
        /* use the resolver to send a query for the mx 
         * records of the domain given on the command line
         */
        p = ldns_resolver_search(res,
                                 domain,
                                 LDNS_RR_TYPE_MX,
                                 LDNS_RR_CLASS_IN,
                                 LDNS_RD);
 
        ldns_rdf_deep_free(domain);
        
        if (!p)  {
                exit(EXIT_FAILURE);
        } else {
                /* retrieve the MX records from the answer section of that
                 * packet
                 */
                mx = ldns_pkt_rr_list_by_type(p,
                                              LDNS_RR_TYPE_MX,
                                              LDNS_SECTION_ANSWER);
                if (!mx) {
                        fprintf(stderr, 
                                        " *** invalid answer name %s after MX query for %s\n",
                                        argv[1], argv[1]);
                        ldns_pkt_free(p);
                        ldns_resolver_deep_free(res);
                        exit(EXIT_FAILURE);
                } else {
                        ldns_rr_list_sort(mx); 
                        ldns_rr_list_print(stdout, mx);
                        ldns_rr_list_deep_free(mx);
                }
        }
        ldns_pkt_free(p);
        ldns_resolver_deep_free(res);
        return 0;
}