84 lines
2.4 KiB
C++
84 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_openvpn_handshake(uint32_t payload, uint32_t len) {
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uint16_t pktlen = ntohs((uint16_t)payload);
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/* First two bytes are the length of the packet (not including the
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* length) */
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if ((uint32_t)(pktlen + 2) != len)
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return false;
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/* Handshake packets have opcodes of either 7 or 8 and key IDs of
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* zero, so the third byte is either 0x38 or 0x40 */
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/* Ref: http://tinyurl.com/37tt3xe */
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if (MATCH(payload, ANY, ANY, 0x38, ANY))
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return true;
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if (MATCH(payload, ANY, ANY, 0x40, ANY))
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return true;
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return false;
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}
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static inline bool match_openvpn(lpi_data_t *data, lpi_module_t *mod UNUSED) {
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if (data->server_port == 53 || data->client_port == 53) {
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return false;
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}
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if (data->payload_len[0] != 0 && !match_openvpn_handshake(data->payload[0], data->payload_len[0]))
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return false;
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if (data->payload_len[1] != 0 && !match_openvpn_handshake(data->payload[1], data->payload_len[1]))
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return false;
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return true;
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}
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static lpi_module_t lpi_openvpn = {
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LPI_PROTO_OPENVPN,
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LPI_CATEGORY_TUNNELLING,
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"OpenVPN",
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4, /* Most of this rule is based on a length field in the header */
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match_openvpn
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};
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void register_openvpn(LPIModuleMap *mod_map) {
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register_protocol(&lpi_openvpn, mod_map);
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}
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