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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
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include "dns.h"
#ifdef HAVE_RESOLV_H
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <sys/types.h>
#include "shared/output.h"
#ifndef PACKETSZ
#define PACKETSZ 512
#endif
char *txtquery(const char *domain, unsigned int *ttl)
{
unsigned char answer[PACKETSZ], *answend, *pt;
char *txt, host[128];
int len, type, qtype;
unsigned int cttl, size, txtlen = 0;
*ttl = 0;
if(res_init() < 0) {
logg("^res_init failed\n");
return NULL;
}
logg("*Querying %s\n", domain);
memset(answer, 0, PACKETSZ);
qtype = T_TXT;
if((len = res_query(domain, C_IN, qtype, answer, PACKETSZ)) < 0 || len > PACKETSZ) {
#ifdef FRESHCLAM_DNS_FIX
/* 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);
qtype=T_ANY;
if((len = res_query(domain, C_IN, qtype, answer, PACKETSZ)) < 0) {
logg("^Can't query %s\n", domain);
return NULL;
}
#else
logg("^Can't query %s\n", domain);
return NULL;
#endif
}
answend = answer + len;
pt = answer + sizeof(HEADER);
if((len = dn_expand(answer, answend, pt, host, sizeof(host))) < 0) {
logg("^dn_expand failed\n");
return NULL;
}
pt += len;
if(pt > answend-4) {
logg("^Bad (too short) DNS reply\n");
return NULL;
}
GETSHORT(type, pt);
if(type != qtype) {
logg("^Broken DNS reply.\n");
return NULL;
}
pt += INT16SZ; /* class */
size = 0;
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;
}
if(!size || (txtlen = *pt) >= size || !txtlen) {
logg("^Broken TXT record (txtlen = %d, size = %d)\n", txtlen, size);
return NULL;
}
if(!(txt = (char *) malloc(txtlen + 1)))
return NULL;
memcpy(txt, pt+1, txtlen);
txt[txtlen] = 0;
*ttl = cttl;
return txt;
}
#elif defined(C_WINDOWS)
/*
* Note: Needs to link with dnsapi.lib.
* The dll behind this library is available from Windows 2000 onward.
* Written by Mark Pizzolato
*/
#include <winsock.h>
#include <string.h>
#include <windows.h>
#include <windns.h>
#include "shared/output.h"
char *txtquery(const char *domain, unsigned int *ttl)
{
PDNS_RECORD pDnsRecord;
char *txt = NULL;
*ttl = 0;
mprintf("*Querying %s\n", domain);
if(DnsQuery_UTF8(domain, DNS_TYPE_TEXT, DNS_QUERY_TREAT_AS_FQDN, NULL, &pDnsRecord, NULL) != 0)
return NULL;
if((pDnsRecord->Data.TXT.dwStringCount > 0) && pDnsRecord->Data.TXT.pStringArray[0]) {
txt = malloc(strlen(pDnsRecord->Data.TXT.pStringArray[0]) + 1);
if(txt)
strcpy(txt, pDnsRecord->Data.TXT.pStringArray[0]);
*ttl = pDnsRecord->dwTtl;
}
DnsRecordListFree(pDnsRecord, DnsFreeRecordList);
return txt;
}
#else
char *txtquery(const char *domain, unsigned int *ttl)
{
*ttl = 1; /* ttl of 1 combined with a NULL return distinguishes a failed lookup from DNS queries not being available */
return NULL;
}
#endif
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