// Provides some very limited but fast packet filter mechanisms

#pragma once

#include "IPAddr.h"
#include "PrefixTable.h"

ZEEK_FORWARD_DECLARE_NAMESPACED(IP_Hdr, zeek);
ZEEK_FORWARD_DECLARE_NAMESPACED(Val, zeek);

class PacketFilter {
public:
	explicit PacketFilter(bool arg_default);
	~PacketFilter()	{}

	// Drops all packets from a particular source (which may be given
	// as an AddrVal or a SubnetVal) which hasn't any of TCP flags set
	// (TH_*) with the given probability (from 0..MAX_PROB).
	void AddSrc(const zeek::IPAddr& src, uint32_t tcp_flags, double probability);
	void AddSrc(zeek::Val* src, uint32_t tcp_flags, double probability);
	void AddDst(const zeek::IPAddr& src, uint32_t tcp_flags, double probability);
	void AddDst(zeek::Val* src, uint32_t tcp_flags, double probability);

	// Removes the filter entry for the given src/dst
	// Returns false if filter doesn not exist.
	bool RemoveSrc(const zeek::IPAddr& src);
	bool RemoveSrc(zeek::Val* dst);
	bool RemoveDst(const zeek::IPAddr& dst);
	bool RemoveDst(zeek::Val* dst);

	// Returns true if packet matches a drop filter
	bool Match(const zeek::IP_Hdr* ip, int len, int caplen);

private:
	struct Filter {
		uint32_t tcp_flags;
		double probability;
	};

	static void DeleteFilter(void* data);

	bool MatchFilter(const Filter& f, const zeek::IP_Hdr& ip, int len, int caplen);

	bool default_match;
	PrefixTable src_filter;
	PrefixTable dst_filter;
};