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152 lines
3.5 KiB
152 lines
3.5 KiB
/*
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* Copyright (C) 2004 Tomasz Kojm <tkojm@clamav.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#if HAVE_CONFIG_H
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#include "clamav-config.h"
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#endif
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#include <stdio.h>
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#include "dns.h"
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#ifdef HAVE_RESOLV_H
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#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>
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#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
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#define PACKETSZ 512
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#endif
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char *txtquery(const char *domain, unsigned int *ttl)
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{
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unsigned char answer[PACKETSZ], *answend, *pt;
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char *txt, host[128];
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int len, type, qtype;
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unsigned int cttl, size, txtlen = 0;
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*ttl = 0;
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if(res_init() < 0) {
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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);
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qtype = T_TXT;
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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
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* handle a TXT-query, but it can resolve an ANY-query to a
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* TXT-record, so we try an ANY-query now. The thing we try
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* to resolve normally only has a TXT-record anyway.
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*/
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memset(answer, 0, PACKETSZ);
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qtype=T_ANY;
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if((len = res_query(domain, C_IN, qtype, answer, PACKETSZ)) < 0) {
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logg("^Can't query %s\n", domain);
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return NULL;
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}
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#else
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logg("^Can't query %s\n", domain);
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return NULL;
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#endif
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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) {
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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) {
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logg("^Bad (too short) DNS reply\n");
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return NULL;
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}
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GETSHORT(type, pt);
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if(type != qtype) {
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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) {
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logg("^second 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-10) {
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logg("^Bad (too short) DNS reply\n");
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return NULL;
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}
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GETSHORT(type, pt);
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pt += INT16SZ; /* class */
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GETLONG(cttl, pt);
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GETSHORT(size, pt);
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if(pt + size < answer || pt + size > answend) {
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logg("^DNS rr overflow\n");
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return NULL;
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}
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} while(type == T_CNAME);
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if(type != T_TXT) {
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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) {
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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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*ttl = cttl;
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return txt;
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}
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#else
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char *txtquery(const char *domain, unsigned int *ttl)
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{
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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;
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}
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#endif
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