85 lines
2.4 KiB
C++
85 lines
2.4 KiB
C++
/*
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*
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* Copyright (c) 2011-2016 The University of Waikato, Hamilton, New Zealand.
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* All rights reserved.
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*
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* This file is part of libprotoident.
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*
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* This code has been developed by the University of Waikato WAND
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* research group. For further information please see http://www.wand.net.nz/
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*
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* libprotoident is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* libprotoident 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#include <string.h>
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#include "libprotoident.h"
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#include "proto_manager.h"
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#include "proto_common.h"
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static inline bool match_reordered_dns(lpi_data_t *data) {
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/* Unfortunately, UDP can get reordered so if there are multiple
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* queries in a flow we cannot guarantee that the first response
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* will have the same ID as the first query.
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*/
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/* Just try and match common request / response flag arrangements */
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if (MATCH(data->payload[0], ANY, ANY, 0x01, 0x00)) {
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if (MATCH(data->payload[1], ANY, ANY, 0x81, 0x80))
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return true;
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}
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if (MATCH(data->payload[1], ANY, ANY, 0x01, 0x00)) {
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if (MATCH(data->payload[0], ANY, ANY, 0x81, 0x80))
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return true;
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}
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return false;
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}
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static inline bool match_dns_udp(lpi_data_t *data, lpi_module_t *mod UNUSED) {
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/* As loath as I am to do this, we probably shouldn't allow any DNS
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* on ports other than 53 */
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if (data->server_port != 53 && data->client_port != 53)
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return false;
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if (match_dns(data))
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return true;
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if (match_reordered_dns(data))
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return true;
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return false;
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}
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static lpi_module_t lpi_dns_udp = {
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LPI_PROTO_UDP_DNS,
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LPI_CATEGORY_SERVICES,
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"DNS",
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10, /* Not a high certainty */
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match_dns_udp
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};
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void register_dns_udp(LPIModuleMap *mod_map) {
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register_protocol(&lpi_dns_udp, mod_map);
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}
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