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/*
* Copyright (c) 2017, Matias Fontanini
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifndef TINS_OFFLINE_PACKET_FILTER_H
#define TINS_OFFLINE_PACKET_FILTER_H
#include <string>
#include <stdint.h>
#include <tins/macros.h>
#ifdef TINS_HAVE_PCAP
#include <tins/data_link_type.h>
namespace Tins {
class PDU;
/**
* \class OfflinePacketFilter
*
* \brief Wraps a pcap filter and matches it against a packet or buffer.
*
* This is a thin wrapper over <i>pcap_offline_filter</i>. You can use
* it to perform packet filtering outside of Sniffer instances.
*
* A potential use case would be if you are capturing packets that are
* sent from another host over UDP. You would recieve UDP packets, then
* parse their content, and apply the OfflinePacketFilter over the
* wrapped packet. For example:
*
* \code
* // Assume we get an UDP packet from somewhere.
* // Inside the payload, there will be a complete packet
* // including its link layer protocol.
* UDP udp = get_packet();
*
* // Create the filter. We'll be expecting Ethernet packets.
* OfflinePacketFilter filter("ip and port 80", DataLinkType<EthernetII>());
*
* // We can use this directly over the inner PDU (assuming it has one)
* // See the notes on the efficiency of doing it this way.
* if(filter.matches_filter(*udp.inner_pdu())) {
* // Matches!
* }
*
* // We can also use the payload. This version it faster and should
* // be preferred over the one above
* const RawPDU& raw = udp.rfind_pdu<RawPDU>();
* const auto& payload = raw.payload();
* if(filter.matches_filter(payload.data(), payload.size())) {
* // Matches!
* }
* \endcode
*/
class TINS_API OfflinePacketFilter {
public:
/**
* Constructs an OfflinePacketFilter object.
*
* \param filter The pcap filter to use.
* \param lt The link layer type to use.
* \param snap_len The snapshot length to use.
*/
template<typename T>
OfflinePacketFilter(const std::string& filter,
const DataLinkType<T>& lt,
unsigned int snap_len = 65535)
: string_filter_(filter) {
init(filter, lt.get_type(), snap_len);
}
/**
* \brief Copy constructor.
*
* Note that during copy construction the pcap filter is
* recompiled. Therefore, it might be somehow expensive to
* copy OfflinePacketFilters.
*
* \param other The filter to be copied.
*/
OfflinePacketFilter(const OfflinePacketFilter& other);
/**
* \brief Copy assignment operator.
*
* \param other The filter to be copied.
*
* \sa OfflinePacketFilter
*/
OfflinePacketFilter& operator=(const OfflinePacketFilter& other);
/**
* Releases the compiled pcap filter and handle.
*/
~OfflinePacketFilter();
/**
* \brief Applies the compiled filter on the provided buffer.
*
* This method uses <i>pcap_offline_filter</i> on the provided buffer
* and returns a bool indicating if the packet pointed by the buffer
* matches the filter.
*
* \param buffer A pointer to a buffer which holds a raw packet.
* \param total_sz The length of the buffer pointed by buffer.
* \return true iff the packet matches the filter.
*/
bool matches_filter(const uint8_t* buffer, uint32_t total_sz) const;
/**
* \brief Applies the compiled filter on the provided packet.
*
* This method checks whether the provided packet matches the filter.
* Since this uses pcap filters and they work over a raw data buffer,
* this method serialices the packet and then applies the filter.
* Therefore, this can be quite expensive to use. If you have access
* to the packet before constructing a PDU from it, it is recommended
* to use the other overload over the raw buffer.
*
* \param pdu The packet to be matched against the filter.
* \return true iff the packet matches the filter.
*/
bool matches_filter(PDU& pdu) const;
private:
void init(const std::string& pcap_filter, int link_type,
unsigned int snap_len);
pcap_t* handle_;
mutable bpf_program filter_;
std::string string_filter_;
};
} // Tins
#endif // TINS_HAVE_PCAP
#endif // TINS_OFFLINE_PACKET_FILTER_H
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