zeek/src/TCP.h

// See the file "COPYING" in the main distribution directory for copyright.

#ifndef TCP_H
#define TCP_H

#include "analyzer/Analyzer.h"
#include "TCP.h"
#include "PacketDumper.h"
#include "IPAddr.h"
#include "TCP_Endpoint.h"
#include "Conn.h"

// We define two classes here:
// - TCP_Analyzer is the analyzer for the TCP protocol itself.
// - TCP_ApplicationAnalyzer is an abstract base class for analyzers for a
//   protocol running on top of TCP.

class PIA_TCP;
class TCP_ApplicationAnalyzer;
class TCP_Reassembler;
class TCP_Endpoint;

class TCP_Flags {
public:
	TCP_Flags(const struct tcphdr* tp)	{ flags = tp->th_flags; }

	bool SYN()	{ return flags & TH_SYN; }
	bool FIN()	{ return flags & TH_FIN; }
	bool RST()	{ return flags & TH_RST; }
	bool ACK()	{ return flags & TH_ACK; }
	bool URG()	{ return flags & TH_URG; }
	bool PUSH()	{ return flags & TH_PUSH; }

protected:
	u_char flags;
};

class TCP_Analyzer : public analyzer::TransportLayerAnalyzer {
public:
	TCP_Analyzer(Connection* conn);
	virtual ~TCP_Analyzer();

	void EnableReassembly();

	// Add a child analyzer that will always get the packets,
	// independently of whether we do any reassembly.
	void AddChildPacketAnalyzer(analyzer::Analyzer* a)
		{ packet_children.push_back(a); a->SetParent(this); }

	// True if the connection has closed in some sense, false otherwise.
	int IsClosed() const	{ return orig->did_close || resp->did_close; }
	int BothClosed() const	{ return orig->did_close && resp->did_close; }

	int IsPartial() const	{ return is_partial; }

	bool HadGap(bool orig) const;

	TCP_Endpoint* Orig() const	{ return orig; }
	TCP_Endpoint* Resp() const	{ return resp; }
	int OrigState() const	{ return orig->state; }
	int RespState() const	{ return resp->state; }
	int OrigPrevState() const	{ return orig->prev_state; }
	int RespPrevState() const	{ return resp->prev_state; }
	uint32 OrigSeq() const	{ return orig->LastSeq(); }
	uint32 RespSeq() const	{ return resp->LastSeq(); }

	// True if either endpoint still has pending data.  closing_endp
	// is an endpoint that has indicated it is closing (i.e., for
	// which we have seen a FIN) - for it, data is pending unless
	// everything's been delivered up to the FIN.  For its peer,
	// the test is whether it has any outstanding, un-acked data.
	int DataPending(TCP_Endpoint* closing_endp);

	virtual void SetContentsFile(unsigned int direction, BroFile* f);
	virtual BroFile* GetContentsFile(unsigned int direction) const;

	// Callback to process a TCP option.
	typedef int (*proc_tcp_option_t)(unsigned int opt, unsigned int optlen,
			const u_char* option, TCP_Analyzer* analyzer,
			bool is_orig, void* cookie);

	// From Analyzer.h
	virtual void UpdateConnVal(RecordVal *conn_val);

	// Needs to be static because it's passed as a pointer-to-function
	// rather than pointer-to-member-function.
	static int ParseTCPOptions(const struct tcphdr* tcp,
			proc_tcp_option_t proc, TCP_Analyzer* analyzer,
			bool is_orig, void* cookie);

	static analyzer::Analyzer* InstantiateAnalyzer(Connection* conn)
		{ return new TCP_Analyzer(conn); }

	static bool Available()	{ return true; }

protected:
	friend class TCP_ApplicationAnalyzer;
	friend class TCP_Reassembler;
	friend class PIA_TCP;

	// Analyzer interface.
	virtual void Init();
	virtual void Done();
	virtual void DeliverPacket(int len, const u_char* data, bool orig, int seq, const IP_Hdr* ip, int caplen);
	virtual void DeliverStream(int len, const u_char* data, bool orig);
	virtual void Undelivered(int seq, int len, bool orig);
	virtual void FlipRoles();
	virtual bool IsReuse(double t, const u_char* pkt);

	// Returns the TCP header pointed to by data (which we assume is
	// aligned), updating data, len & caplen.  Returns nil if the header
	// isn't fully present.
	const struct tcphdr* ExtractTCP_Header(const u_char*& data, int& len,
						int& caplen);

	// Returns true if the checksum is valid, false if not (and in which
	// case also updates the status history of the endpoint).
	bool ValidateChecksum(const struct tcphdr* tp, TCP_Endpoint* endpoint,
				int len, int caplen);

	// Update analysis based on flag combinations.  The endpoint, base_seq
	// and len are needed for tracking various history information.
	// dst_port is needed for trimming of FIN packets.
	void CheckFlagCombos(TCP_Flags flags, TCP_Endpoint* endpoint,
				uint32 base_seq, int len, int dst_port);

	void UpdateWindow(TCP_Endpoint* endpoint, unsigned int window,
					uint32 base_seq, uint32 ack_seq,
					TCP_Flags flags);

	void ProcessSYN(const IP_Hdr* ip, const struct tcphdr* tp,
			uint32 tcp_hdr_len, int& seq_len,
			TCP_Endpoint* endpoint, TCP_Endpoint* peer,
			uint32 base_seq, uint32 ack_seq,
			const IPAddr& orig_addr,
			int is_orig, TCP_Flags flags);

	void ProcessFIN(double t, TCP_Endpoint* endpoint, int& seq_len,
			uint32 base_seq);

	void ProcessRST(double t, TCP_Endpoint* endpoint, const IP_Hdr* ip,
			uint32 base_seq, int len, int& seq_len);

	void ProcessACK(TCP_Endpoint* endpoint, TCP_Endpoint* peer,
			uint32 ack_seq, int is_orig, TCP_Flags flags);

	void ProcessFlags(double t, const IP_Hdr* ip, const struct tcphdr* tp,
			uint32 tcp_hdr_len, int len, int& seq_len,
			TCP_Endpoint* endpoint, TCP_Endpoint* peer,
			uint32 base_seq, uint32 ack_seq,
			const IPAddr& orig_addr,
			int is_orig, TCP_Flags flags);

	void TransitionFromInactive(double t, TCP_Endpoint* endpoint,
					uint32 base_seq, uint32 last_seq,
					int SYN);

	// Update the state machine of the TCPs based on the activity.  This
	// includes our pseudo-states such as TCP_ENDPOINT_PARTIAL.
	//
	// On return, do_close is true if we should consider the connection
	// as closed, and gen_event if we shouuld generate an event about
	// this fact.
	void UpdateStateMachine(double t,
			TCP_Endpoint* endpoint, TCP_Endpoint* peer,
			uint32 base_seq, uint32 ack_seq, uint32 last_seq,
			int len, int delta_last, int is_orig, TCP_Flags flags,
			int& do_close, int& gen_event);

	void UpdateInactiveState(double t,
				TCP_Endpoint* endpoint, TCP_Endpoint* peer,
				uint32 base_seq, uint32 ack_seq,
				int len, int is_orig, TCP_Flags flags,
				int& do_close, int& gen_event);

	void UpdateSYN_SentState(double t,
				TCP_Endpoint* endpoint, TCP_Endpoint* peer,
				uint32 base_seq, uint32 last_seq,
				int len, int is_orig, TCP_Flags flags,
				int& do_close, int& gen_event);

	void UpdateEstablishedState(double t,
				TCP_Endpoint* endpoint, TCP_Endpoint* peer,
				uint32 base_seq, uint32 last_seq,
				int is_orig, TCP_Flags flags,
				int& do_close, int& gen_event);

	void UpdateClosedState(double t, TCP_Endpoint* endpoint,
				int delta_last, TCP_Flags flags,
				int& do_close);

	void UpdateResetState(int len, TCP_Flags flags, TCP_Endpoint* endpoint,
				uint32 base_seq, uint32 last_seq);

	void GeneratePacketEvent(TCP_Endpoint* endpoint, TCP_Endpoint* peer,
					uint32 base_seq, uint32 ack_seq,
					const u_char* data, int len, int caplen,
					int is_orig, TCP_Flags flags);

	int DeliverData(double t, const u_char* data, int len, int caplen,
			const IP_Hdr* ip, const struct tcphdr* tp,
			TCP_Endpoint* endpoint, uint32 base_seq,
			int is_orig, TCP_Flags flags);

	void CheckRecording(int need_contents, TCP_Flags flags);
	void CheckPIA_FirstPacket(int is_orig, const IP_Hdr* ip);

	// Returns the difference between last_seq and the last sequence
	// seen by the endpoint (may be negative).
	int UpdateLastSeq(TCP_Endpoint* endpoint, uint32 last_seq,
				TCP_Flags flags);

	friend class ConnectionTimer;
	void AttemptTimer(double t);
	void PartialCloseTimer(double t);
	void ExpireTimer(double t);
	void ResetTimer(double t);
	void DeleteTimer(double t);
	void ConnDeleteTimer(double t);

	void EndpointEOF(TCP_Reassembler* endp);
	void ConnectionClosed(TCP_Endpoint* endpoint,
					TCP_Endpoint* peer, int gen_event);
	void ConnectionFinished(int half_finished);
	void ConnectionReset();
	void PacketWithRST();

	void SetReassembler(TCP_Reassembler* rorig, TCP_Reassembler* rresp);

	Val* BuildSYNPacketVal(int is_orig,
				const IP_Hdr* ip, const struct tcphdr* tcp);

	RecordVal* BuildOSVal(int is_orig, const IP_Hdr* ip,
				const struct tcphdr* tcp, uint32 tcp_hdr_len);

	// Needs to be static because it's passed as a pointer-to-function
	// rather than pointer-to-member-function.
	static int TCPOptionEvent(unsigned int opt, unsigned int optlen,
				const u_char* option, TCP_Analyzer* analyzer,
				  bool is_orig, void* cookie);

private:
	TCP_Endpoint* orig;
	TCP_Endpoint* resp;

	typedef list<analyzer::Analyzer*> analyzer_list;
	analyzer_list packet_children;

	unsigned int first_packet_seen: 2;
	unsigned int reassembling: 1;
	unsigned int is_partial: 1;
	unsigned int is_active: 1;
	unsigned int finished: 1;

	// Whether we're waiting on final data delivery before closing
	// this connection.
	unsigned int close_deferred: 1;

	// Whether to generate an event when we finally do close it.
	unsigned int deferred_gen_event: 1;

	// Whether we have seen the first ACK from the originator.
	unsigned int seen_first_ACK: 1;
};

class TCP_ApplicationAnalyzer : public analyzer::Analyzer {
public:
	TCP_ApplicationAnalyzer(const char* name, Connection* conn)
	: Analyzer(name, conn)
		{ tcp = 0; }

	virtual ~TCP_ApplicationAnalyzer()	{ }

	// This may be nil if we are not directly associated with a TCP
	// analyzer (e.g., we're part of a tunnel decapsulation pipeline).
	TCP_Analyzer* TCP()
		{
		return tcp ?
			tcp :
			static_cast<TCP_Analyzer*>(Conn()->FindAnalyzer("TCP"));
		}

	void SetTCP(TCP_Analyzer* arg_tcp)	{ tcp = arg_tcp; }

	// The given endpoint's data delivery is complete.
	virtual void EndpointEOF(bool is_orig);

	// Called whenever an end enters TCP_ENDPOINT_CLOSED or
	// TCP_ENDPOINT_RESET.  If gen_event is true and the connection
	// is now fully closed, a connection_finished event will be
	// generated; otherwise not.
	virtual void ConnectionClosed(TCP_Endpoint* endpoint,
					TCP_Endpoint* peer, int gen_event);
	virtual void ConnectionFinished(int half_finished);
	virtual void ConnectionReset();

	// Called whenever a RST packet is seen - sometimes the invocation
	// of ConnectionReset is delayed.
	virtual void PacketWithRST();

	virtual void DeliverPacket(int len, const u_char* data, bool orig,
					int seq, const IP_Hdr* ip, int caplen);
	virtual void Init();

	// This suppresses violations if the TCP connection wasn't
	// fully established.
	virtual void ProtocolViolation(const char* reason,
					const char* data = 0, int len = 0);

	// "name" and "val" both now belong to this object, which needs to
	//  delete them when done with them.
	virtual void SetEnv(bool orig, char* name, char* val);

private:
	TCP_Analyzer* tcp;
};

class TCP_SupportAnalyzer : public analyzer::SupportAnalyzer {
public:
	TCP_SupportAnalyzer(const char* name, Connection* conn, bool arg_orig)
		: analyzer::SupportAnalyzer(name, conn, arg_orig)	{ }

	virtual ~TCP_SupportAnalyzer() {}

	// These are passed on from TCP_Analyzer.
	virtual void EndpointEOF(bool is_orig)	{ }
	virtual void ConnectionClosed(TCP_Endpoint* endpoint,
					TCP_Endpoint* peer, int gen_event) 	{ }
	virtual void ConnectionFinished(int half_finished)	{ }
	virtual void ConnectionReset()	{ }
	virtual void PacketWithRST()	{ }
};


class TCPStats_Endpoint {
public:
	TCPStats_Endpoint(TCP_Endpoint* endp);

	int DataSent(double t, int seq, int len, int caplen, const u_char* data,
			const IP_Hdr* ip, const struct tcphdr* tp);

	RecordVal* BuildStats();

protected:
	TCP_Endpoint* endp;
	int num_pkts;
	int num_rxmit;
	int num_rxmit_bytes;
	int num_in_order;
	int num_OO;
	int num_repl;
	int max_top_seq;
	int last_id;
	int endian_type;
};

class TCPStats_Analyzer : public TCP_ApplicationAnalyzer {
public:
	TCPStats_Analyzer(Connection* c);
	~TCPStats_Analyzer();

	virtual void Init();
	virtual void Done();

	static analyzer::Analyzer* InstantiateAnalyzer(Connection* conn)
		{ return new TCPStats_Analyzer(conn); }

	static bool Available()	{ return conn_stats || tcp_rexmit; }

protected:
	virtual void DeliverPacket(int len, const u_char* data, bool is_orig,
					int seq, const IP_Hdr* ip, int caplen);

	TCPStats_Endpoint* orig_stats;
	TCPStats_Endpoint* resp_stats;
};

#endif