path: root/epan/dissectors/packet-tcp.h

/* packet-tcp.h
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef __PACKET_TCP_H__
#define __PACKET_TCP_H__

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

#include "ws_symbol_export.h"

#include <epan/conversation.h>
#include <epan/wmem/wmem.h>

/* TCP flags */
#define TH_FIN  0x0001
#define TH_SYN  0x0002
#define TH_RST  0x0004
#define TH_PUSH 0x0008
#define TH_ACK  0x0010
#define TH_URG  0x0020
#define TH_ECN  0x0040
#define TH_CWR  0x0080
#define TH_NS   0x0100
#define TH_RES  0x0E00 /* 3 reserved bits */
#define TH_MASK 0x0FFF

/* Idea for gt: either x > y, or y is much bigger (assume wrap) */
#define GT_SEQ(x, y) ((gint32)((y) - (x)) < 0)
#define LT_SEQ(x, y) ((gint32)((x) - (y)) < 0)
#define GE_SEQ(x, y) ((gint32)((y) - (x)) <= 0)
#define LE_SEQ(x, y) ((gint32)((x) - (y)) <= 0)
#define EQ_SEQ(x, y) (x) == (y)

/* the tcp header structure, passed to tap listeners */
typedef struct tcpheader {
	guint32 th_seq;
	guint32 th_ack;
	gboolean th_have_seglen;	/* TRUE if th_seglen is valid */
	guint32 th_seglen;
	guint32 th_win;   /* make it 32 bits so we can handle some scaling */
	guint16 th_sport;
	guint16 th_dport;
	guint8  th_hlen;
	guint16 th_flags;
	guint32 th_stream; /* this stream index field is included to help differentiate when address/port pairs are reused */
	address ip_src;
	address ip_dst;

	/* This is the absolute maximum we could find in TCP options (RFC2018, section 3) */
	#define MAX_TCP_SACK_RANGES 4
	guint8  num_sack_ranges;
	guint32 sack_left_edge[MAX_TCP_SACK_RANGES];
	guint32 sack_right_edge[MAX_TCP_SACK_RANGES];
} tcp_info_t;

/*
 * Private data passed from the TCP dissector to subdissectors.
 */
struct tcpinfo {
	guint32 seq;             /* Sequence number of first byte in the data */
	guint32 nxtseq;          /* Sequence number of first byte after data */
	guint32 lastackseq;      /* Sequence number of last ack */
	gboolean is_reassembled; /* This is reassembled data. */
	gboolean urgent;         /* TRUE if "urgent_pointer" is valid */
	guint16	urgent_pointer;  /* Urgent pointer value for the current packet. */
};

/*
 * Loop for dissecting PDUs within a TCP stream; assumes that a PDU
 * consists of a fixed-length chunk of data that contains enough information
 * to determine the length of the PDU, followed by rest of the PDU.
 *
 * The first three arguments are the arguments passed to the dissector
 * that calls this routine.
 *
 * "proto_desegment" is the dissector's flag controlling whether it should
 * desegment PDUs that cross TCP segment boundaries.
 *
 * "fixed_len" is the length of the fixed-length part of the PDU.
 *
 * "get_pdu_len()" is a routine called to get the length of the PDU from
 * the fixed-length part of the PDU; it's passed "pinfo", "tvb" and "offset".
 *
 * "dissect_pdu()" is the routine to dissect a PDU.
 */
WS_DLL_PUBLIC void
tcp_dissect_pdus(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
		 gboolean proto_desegment, guint fixed_len,
		 guint (*get_pdu_len)(packet_info *, tvbuff_t *, int, void*),
		 new_dissector_t dissect_pdu, void* dissector_data);

extern struct tcp_multisegment_pdu *
pdu_store_sequencenumber_of_next_pdu(packet_info *pinfo, guint32 seq, guint32 nxtpdu, wmem_tree_t *multisegment_pdus);

typedef struct _tcp_unacked_t {
	struct _tcp_unacked_t *next;
	guint32 frame;
	guint32	seq;
	guint32	nextseq;
	nstime_t ts;
} tcp_unacked_t;

struct tcp_acked {
	guint32 frame_acked;
	nstime_t ts;

	guint32  rto_frame;
	nstime_t rto_ts;	/* Time since previous packet for
				   retransmissions. */
	guint16 flags; /* see TCP_A_* in packet-tcp.c */
	guint32 dupack_num;	/* dup ack number */
	guint32 dupack_frame;	/* dup ack to frame # */
	guint32 bytes_in_flight; /* number of bytes in flight */
};

/* One instance of this structure is created for each pdu that spans across
 * multiple tcp segments.
 */
struct tcp_multisegment_pdu {
	guint32 seq;
	guint32 nxtpdu;
	guint32 first_frame;
	guint32 last_frame;
	nstime_t last_frame_time;
	guint32 flags;
#define MSP_FLAGS_REASSEMBLE_ENTIRE_SEGMENT	0x00000001
};

typedef struct _tcp_flow_t {
	gboolean base_seq_set; /* true if base seq set */
	guint32 base_seq;	/* base seq number (used by relative sequence numbers)*/
	tcp_unacked_t *segments;
	guint32 fin;		/* frame number of the final FIN */
	guint32 lastack;	/* last seen ack */
	nstime_t lastacktime;	/* Time of the last ack packet */
	guint32 lastnondupack;	/* frame number of last seen non dupack */
	guint32 dupacknum;	/* dupack number */
	guint32 nextseq;	/* highest seen nextseq */
	guint32 maxseqtobeacked;/* highest seen continuous seq number (without hole in the stream) from the fwd party,
				 * this is the maximum seq number that can be acked by the rev party in normal case.
				 * If the rev party sends an ACK beyond this seq number it indicates TCP_A_ACK_LOST_PACKET contition */
	guint32 nextseqframe;	/* frame number for segment with highest
				 * sequence number
				 */
	nstime_t nextseqtime;	/* Time of the nextseq packet so we can
				 * distinguish between retransmission,
				 * fast retransmissions and outoforder
				 */
	guint32 window;		/* last seen window */
	gint16	win_scale;	/* -1 is we don't know, -2 is window scaling is not used */
	gint16  scps_capable;   /* flow advertised scps capabilities */
	guint16 maxsizeacked;   /* 0 if not yet known */
	gboolean valid_bif;     /* if lost pkts, disable BiF until ACK is recvd */

/* This tcp flow/session contains only one single PDU and should
 * be reassembled until the final FIN segment.
 */
#define TCP_FLOW_REASSEMBLE_UNTIL_FIN	0x0001
	guint16 flags;

	/* see TCP_A_* in packet-tcp.c */
	guint32 lastsegmentflags;

	/* This tree is indexed by sequence number and keeps track of all
	 * all pdus spanning multiple segments for this flow.
	 */
	wmem_tree_t *multisegment_pdus;

	/* Process info, currently discovered via IPFIX */
	guint32 process_uid;    /* UID of local process */
	guint32 process_pid;    /* PID of local process */
	gchar *username;	/* Username of the local process */
	gchar *command;         /* Local process name + path + args */
} tcp_flow_t;


struct tcp_analysis {
	/* These two structs are managed based on comparing the source
	 * and destination addresses and, if they're equal, comparing
	 * the source and destination ports.
	 *
	 * If the source is greater than the destination, then stuff
	 * sent from src is in ual1.
	 *
	 * If the source is less than the destination, then stuff
	 * sent from src is in ual2.
	 *
	 * XXX - if the addresses and ports are equal, we don't guarantee
	 * the behavior.
	 */
	tcp_flow_t	flow1;
	tcp_flow_t	flow2;

	/* These pointers are set by get_tcp_conversation_data()
	 * fwd point in the same direction as the current packet
	 * and rev in the reverse direction
	 */
	tcp_flow_t	*fwd;
	tcp_flow_t	*rev;

	/* This pointer is NULL   or points to a tcp_acked struct if this
	 * packet has "interesting" properties such as being a KeepAlive or
	 * similar
	 */
	struct tcp_acked *ta;
	/* This structure contains a tree containing all the various ta's
	 * keyed by frame number.
	 */
	wmem_tree_t	*acked_table;

	/* Remember the timestamp of the first frame seen in this tcp
	 * conversation to be able to calculate a relative time compared
	 * to the start of this conversation
	 */
	nstime_t	ts_first;

        /* Remember the timestamp of the most recent SYN in this conversation in
         * order to calculate the first_rtt below. Not necessarily ts_first, if
         * the SYN is retransmitted. */
	nstime_t	ts_mru_syn;

        /* If we have the handshake, remember the RTT between the initial SYN
         * and ACK for use detecting out-of-order segments. */
	nstime_t	ts_first_rtt;

	/* Remember the timestamp of the frame that was last seen in this
	 * tcp conversation to be able to calculate a delta time compared
	 * to previous frame in this conversation
	 */
	nstime_t	ts_prev;

	/* Keep track of tcp stream numbers instead of using the conversation
	 * index (as how it was done before). This prevents gaps in the
	 * stream index numbering
	 */
	guint32         stream;

	/* Remembers the server port on the SYN (or SYN|ACK) packet to
	 * help determine which dissector to call
	 */
	guint16 server_port;
};

/* Structure that keeps per packet data. First used to be able
 * to calculate the time_delta from the last seen frame in this
 * TCP conversation. Can be extended for future use.
 */
struct tcp_per_packet_data_t {
	nstime_t	ts_del;
};


WS_DLL_PUBLIC void dissect_tcp_payload(tvbuff_t *tvb, packet_info *pinfo, int offset,
				guint32 seq, guint32 nxtseq, guint32 sport,
				guint32 dport, proto_tree *tree,
				proto_tree *tcp_tree,
				struct tcp_analysis *tcpd, struct tcpinfo *tcpinfo);

WS_DLL_PUBLIC struct tcp_analysis *get_tcp_conversation_data(conversation_t *conv,
                                packet_info *pinfo);

WS_DLL_PUBLIC gboolean decode_tcp_ports(tvbuff_t *, int, packet_info *, proto_tree *, int, int, struct tcp_analysis *, struct tcpinfo *);

/** Associate process information with a given flow
 *
 * @param frame_num The frame number
 * @param local_addr The local IPv4 or IPv6 address of the process
 * @param remote_addr The remote IPv4 or IPv6 address of the process
 * @param local_port The local TCP port of the process
 * @param remote_port The remote TCP port of the process
 * @param uid The numeric user ID of the process
 * @param pid The numeric PID of the process
 * @param username Ephemeral string containing the full or partial process name
 * @param command Ephemeral string containing the full or partial process name
 */
extern void add_tcp_process_info(guint32 frame_num, address *local_addr, address *remote_addr, guint16 local_port, guint16 remote_port, guint32 uid, guint32 pid, gchar *username, gchar *command);

/** Get the current number of TCP streams
 *
 * @return The number of TCP streams
 */
WS_DLL_PUBLIC guint32 get_tcp_stream_count(void);

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif