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/* |
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* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2007-2013 Sourcefire, Inc.
* Copyright (C) 2004-2007 Tomasz Kojm <tkojm@clamav.net>2004 Tomasz Kojm <tkojm@clamav.net> |
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*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA. |
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*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
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#include <stdio.h>
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#include "dns.h" |
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#ifdef HAVE_RESOLV_H
#include <string.h> |
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#include <sys/types.h> |
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#ifndef _WIN32 |
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#include <netinet/in.h>
#include <arpa/nameser.h> |
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#endif |
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#include <resolv.h>
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#include "shared/output.h"
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#ifndef PACKETSZ
#define PACKETSZ 512
#endif
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char * |
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dnsquery(const char *domain, int qtype, unsigned int *ttl) |
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{ |
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unsigned char answer[PACKETSZ], *answend, *pt;
char *txt, host[128];
int len, type;
unsigned int cttl, size, txtlen = 0;
if (ttl)
*ttl = 0; |
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if (res_init() < 0) {
logg("^res_init failed\n"); |
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return NULL; |
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}
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logg("*Querying %s\n", domain); |
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memset(answer, 0, PACKETSZ);
if ((len = res_query(domain, C_IN, qtype, answer, PACKETSZ)) < 0 || len > PACKETSZ) { |
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#ifdef FRESHCLAM_DNS_FIX |
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/* The DNS server in the SpeedTouch Alcatel 510 modem can't
* handle a TXT-query, but it can resolve an ANY-query to a
* TXT-record, so we try an ANY-query now. The thing we try
* to resolve normally only has a TXT-record anyway.
*/ |
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memset(answer, 0, PACKETSZ); |
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if (qtype == T_TXT)
qtype = T_ANY; |
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if ((len = res_query(domain, C_IN, qtype, answer, PACKETSZ)) < 0) {
logg("%cCan't query %s\n",
(qtype == T_TXT || qtype == T_ANY) ? '^' : '*', domain); |
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return NULL;
} |
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#else |
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logg("%cCan't query %s\n", (qtype == T_TXT) ? '^' : '*', domain); |
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return NULL; |
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#endif |
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} |
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if (qtype != T_TXT && qtype != T_ANY) { |
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if (ttl)
*ttl = 2;
return NULL; |
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} |
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|
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answend = answer + len; |
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pt = answer + sizeof(HEADER); |
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if ((len = dn_expand(answer, answend, pt, host, sizeof(host))) < 0) {
logg("^dn_expand failed\n"); |
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return NULL; |
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}
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pt += len; |
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if (pt > answend - 4) {
logg("^Bad (too short) DNS reply\n"); |
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return NULL; |
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} |
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|
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GETSHORT(type, pt);
if (type != qtype) {
logg("^Broken DNS reply.\n"); |
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return NULL; |
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}
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pt += INT16SZ; /* class */ |
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size = 0; |
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do { /* recurse through CNAME rr's */ |
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pt += size; |
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if ((len = dn_expand(answer, answend, pt, host, sizeof(host))) < 0) {
logg("^second dn_expand failed\n"); |
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return NULL;
}
pt += len; |
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if (pt > answend - 10) {
logg("^Bad (too short) DNS reply\n"); |
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return NULL;
} |
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GETSHORT(type, pt);
pt += INT16SZ; /* class */
GETLONG(cttl, pt);
GETSHORT(size, pt);
if (pt + size < answer || pt + size > answend) {
logg("^DNS rr overflow\n"); |
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return NULL;
} |
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} while (type == T_CNAME); |
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if (type != T_TXT) {
logg("^Not a TXT record\n"); |
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return NULL; |
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}
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if (!size || (txtlen = *pt) >= size || !txtlen) {
logg("^Broken TXT record (txtlen = %d, size = %d)\n", txtlen, size); |
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return NULL; |
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}
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if (!(txt = (char *)malloc(txtlen + 1))) |
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return NULL; |
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memcpy(txt, pt + 1, txtlen); |
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txt[txtlen] = 0; |
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if (ttl)
*ttl = cttl; |
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return txt;
}
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#else
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char * |
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dnsquery(const char *domain, int qtype, unsigned int *ttl) |
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{ |
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if (ttl) |
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*ttl = 1; /* ttl of 1 combined with a NULL return distinguishes a failed lookup from DNS queries not being available */ |
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return NULL;
}
#endif |