136 lines
3.4 KiB
C
136 lines
3.4 KiB
C
/*-
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* Copyright (c) 2012 Baptiste Daroussin <bapt@FreeBSD.org>
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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
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* are met:
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* 1. 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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* without modification, immediately at the beginning of the file.
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* 2. 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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* 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
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <stdlib.h>
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#include <string.h>
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#include <netinet/in.h>
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#include <resolv.h>
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#include "dns_utils.h"
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typedef union {
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HEADER hdr;
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unsigned char buf[1024];
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} dns_query;
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struct dns_srvinfo *
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dns_getsrvinfo(const char *zone)
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{
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struct dns_srvinfo **res, *first;
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unsigned char *end, *p;
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char host[MAXHOSTNAMELEN];
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dns_query q;
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int len, qdcount, ancount, n, i;
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unsigned int type, class, ttl, priority, weight, port;
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if ((len = res_query(zone, C_IN, T_SRV, q.buf, sizeof(q.buf))) == -1 ||
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len < (int)sizeof(HEADER))
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return (NULL);
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qdcount = ntohs(q.hdr.qdcount);
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ancount = ntohs(q.hdr.ancount);
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end = q.buf + len;
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p = q.buf + sizeof(HEADER);
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while(qdcount > 0 && p < end) {
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qdcount--;
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if((len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN)) < 0)
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return (NULL);
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p += len + NS_QFIXEDSZ;
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}
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res = calloc(ancount, sizeof(struct dns_srvinfo));
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if (res == NULL)
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return (NULL);
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n = 0;
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while (ancount > 0 && p < end) {
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ancount--;
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len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN);
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if (len < 0) {
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for (i = 0; i < n; i++)
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free(res[i]);
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free(res);
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return NULL;
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}
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p += len;
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NS_GET16(type, p);
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NS_GET16(class, p);
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NS_GET32(ttl, p);
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NS_GET16(len, p);
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if (type != T_SRV) {
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p += len;
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continue;
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}
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NS_GET16(priority, p);
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NS_GET16(weight, p);
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NS_GET16(port, p);
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len = dn_expand(q.buf, end, p, host, MAXHOSTNAMELEN);
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if (len < 0) {
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for (i = 0; i < n; i++)
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free(res[i]);
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free(res);
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return (NULL);
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}
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res[n] = malloc(sizeof(struct dns_srvinfo));
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if (res[n] == NULL) {
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for (i = 0; i < n; i++)
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free(res[i]);
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free(res);
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return (NULL);
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}
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res[n]->type = type;
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res[n]->class = class;
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res[n]->ttl = ttl;
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res[n]->priority = priority;
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res[n]->weight = weight;
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res[n]->port = port;
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res[n]->next = NULL;
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strlcpy(res[n]->host, host, MAXHOSTNAMELEN);
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p += len;
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n++;
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}
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for (i = 0; i < n - 1; i++)
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res[i]->next = res[i + 1];
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first = res[0];
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free(res);
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return (first);
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}
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