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/*
* Copyright (C) 2004 Tomasz Kojm <tkojm@clamav.net>
*
* 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 *
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;
if (res_init () < 0)
{
logg ("^res_init failed\n");
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.
*/
memset (answer, 0, PACKETSZ);
if (qtype == T_TXT)
qtype = T_ANY;
if ((len = res_query (domain, C_IN, qtype, answer, PACKETSZ)) < 0)
{
logg ("%cCan't query %s\n",
(qtype == T_TXT || qtype == T_ANY) ? '^' : '*', domain);
return NULL;
} |
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#else |
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logg ("%cCan't query %s\n", (qtype == T_TXT) ? '^' : '*', domain);
return NULL; |
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#endif |
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} |
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if (qtype != T_TXT && qtype != T_ANY)
{
if (ttl)
*ttl = 2;
return NULL; |
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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");
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");
return NULL; |
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} |
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GETSHORT (type, pt);
if (type != qtype)
{
logg ("^Broken DNS reply.\n");
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 */
pt += size;
if ((len = dn_expand (answer, answend, pt, host, sizeof (host))) < 0)
{
logg ("^second dn_expand failed\n");
return NULL;
}
pt += len;
if (pt > answend - 10)
{
logg ("^Bad (too short) DNS reply\n");
return NULL;
}
GETSHORT (type, pt);
pt += INT16SZ; /* class */
GETLONG (cttl, pt);
GETSHORT (size, pt);
if (pt + size < answer || pt + size > answend)
{
logg ("^DNS rr overflow\n");
return NULL;
}
}
while (type == T_CNAME);
if (type != T_TXT)
{
logg ("^Not a TXT record\n");
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);
return NULL; |
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}
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if (!(txt = (char *) malloc (txtlen + 1)))
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 *
dnsquery (const char *domain, int qtype, unsigned int *ttl) |
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{ |
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if (ttl)
*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 |