xref: /freebsd/sys/netinet/tcp_log_buf.h (revision 69c7c81190580ade16e608c6edaaa9f63dcd9052)

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2016-2020 Netflix, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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 AUTHOR 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 AUTHOR 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.
 *
 * $FreeBSD$
 */

#ifndef __tcp_log_buf_h__
#define __tcp_log_buf_h__

#define	TCP_LOG_REASON_LEN	32
#define	TCP_LOG_TAG_LEN		32
#define	TCP_LOG_BUF_VER		(9)

/*
 * Because the (struct tcp_log_buffer) includes 8-byte uint64_t's, it requires
 * 8-byte alignment to work properly on all platforms. Therefore, we will
 * enforce 8-byte alignment for all the structures that may appear by
 * themselves (instead of being embedded in another structure) in a data
 * stream.
 */
#define	ALIGN_TCP_LOG		__aligned(8)

/* Information about the socketbuffer state. */
struct tcp_log_sockbuf
{
	uint32_t	tls_sb_acc;	/* available chars (sb->sb_acc) */
	uint32_t	tls_sb_ccc;	/* claimed chars (sb->sb_ccc) */
	uint32_t	tls_sb_spare;	/* spare */
};

/* Optional, verbose information that may be appended to an event log. */
struct tcp_log_verbose
{
#define	TCP_FUNC_LEN	32
	char		tlv_snd_frm[TCP_FUNC_LEN]; /* tcp_output() caller */
	char		tlv_trace_func[TCP_FUNC_LEN]; /* Function that
							 generated trace */
	uint32_t	tlv_trace_line;	/* Line number that generated trace */
	uint8_t		_pad[4];
} ALIGN_TCP_LOG;

/* Internal RACK state variables. */
struct tcp_log_rack
{
	uint32_t	tlr_rack_rtt;		/* rc_rack_rtt */
	uint8_t		tlr_state;		/* Internal RACK state */
	uint8_t		_pad[3];		/* Padding */
};

struct tcp_log_bbr {
	uint64_t cur_del_rate;
	uint64_t delRate;
	uint64_t rttProp;
	uint64_t bw_inuse;
	uint32_t inflight;
	uint32_t applimited;
	uint32_t delivered;
	uint32_t timeStamp;
	uint32_t epoch;
	uint32_t lt_epoch;
	uint32_t pkts_out;
	uint32_t flex1;
	uint32_t flex2;
	uint32_t flex3;
	uint32_t flex4;
	uint32_t flex5;
	uint32_t flex6;
	uint32_t lost;
	uint16_t pacing_gain;
	uint16_t cwnd_gain;
	uint16_t flex7;
	uint8_t bbr_state;
	uint8_t bbr_substate;
	uint8_t inhpts;
	uint8_t __spare;
	uint8_t use_lt_bw;
	uint8_t flex8;
	uint32_t pkt_epoch;
};

/* shadows tcp_log_bbr struct element sizes */
struct tcp_log_raw {
	uint64_t u64_flex[4];
	uint32_t u32_flex[14];
	uint16_t u16_flex[3];
	uint8_t u8_flex[6];
	uint32_t u32_flex2[1];
};

struct tcp_log_uint64 {
	uint64_t u64_flex[13];
};

struct tcp_log_sendfile {
	uint64_t offset;
	uint64_t length;
	uint32_t flags;
};

/*
 * tcp_log_stackspecific is currently being used as "event specific" log
 * info by all stacks (i.e. struct tcp_log_bbr is used for generic event
 * logging). Until this is cleaned up more generically and throughout,
 * allow events to use the same space in the union.
 */
union tcp_log_stackspecific
{
	struct tcp_log_rack u_rack;
	struct tcp_log_bbr u_bbr;
	struct tcp_log_sendfile u_sf;
	struct tcp_log_raw u_raw;	/* "raw" log access */
	struct tcp_log_uint64 u64_raw;	/* just u64's - used by process info */
};

typedef union tcp_log_stackspecific tcp_log_eventspecific_t;

struct tcp_log_buffer
{
	/* Event basics */
	struct timeval	tlb_tv;		/* Timestamp of trace */
	uint32_t	tlb_ticks;	/* Timestamp of trace */
	uint32_t	tlb_sn;		/* Serial number */
	uint8_t		tlb_stackid;	/* Stack ID */
	uint8_t		tlb_eventid;	/* Event ID */
	uint16_t	tlb_eventflags;	/* Flags for the record */
#define	TLB_FLAG_RXBUF		0x0001	/* Includes receive buffer info */
#define	TLB_FLAG_TXBUF		0x0002	/* Includes send buffer info */
#define	TLB_FLAG_HDR		0x0004	/* Includes a TCP header */
#define	TLB_FLAG_VERBOSE	0x0008	/* Includes function/line numbers */
#define	TLB_FLAG_STACKINFO	0x0010	/* Includes stack-specific info */
	int		tlb_errno;	/* Event error (if any) */

	/* Internal session state */
	struct tcp_log_sockbuf tlb_rxbuf; /* Receive buffer */
	struct tcp_log_sockbuf tlb_txbuf; /* Send buffer */

	int		tlb_state;	/* TCPCB t_state */
	uint32_t	tlb_starttime;	/* TCPCB t_starttime */
	uint32_t	tlb_iss;	/* TCPCB iss */
	uint32_t	tlb_flags;	/* TCPCB flags */
	uint32_t	tlb_snd_una;	/* TCPCB snd_una */
	uint32_t	tlb_snd_max;	/* TCPCB snd_max */
	uint32_t	tlb_snd_cwnd;	/* TCPCB snd_cwnd */
	uint32_t	tlb_snd_nxt;	/* TCPCB snd_nxt */
	uint32_t	tlb_snd_recover;/* TCPCB snd_recover */
	uint32_t	tlb_snd_wnd;	/* TCPCB snd_wnd */
	uint32_t	tlb_snd_ssthresh; /* TCPCB snd_ssthresh */
	uint32_t	tlb_srtt;	/* TCPCB t_srtt */
	uint32_t	tlb_rttvar;	/* TCPCB t_rttvar */
	uint32_t	tlb_rcv_up;	/* TCPCB rcv_up */
	uint32_t	tlb_rcv_adv;	/* TCPCB rcv_adv */
	uint32_t	tlb_flags2;	/* TCPCB t_flags2 */
	uint32_t	tlb_rcv_nxt;	/* TCPCB rcv_nxt */
	uint32_t	tlb_rcv_wnd;	/* TCPCB rcv_wnd */
	uint32_t	tlb_dupacks;	/* TCPCB t_dupacks */
	int		tlb_segqlen;	/* TCPCB segqlen */
	int		tlb_snd_numholes; /* TCPCB snd_numholes */
	uint32_t	tlb_flex1;	/* Event specific information */
	uint32_t	tlb_flex2;	/* Event specific information */
	uint32_t	tlb_fbyte_in;	/* TCPCB first byte in time */
	uint32_t	tlb_fbyte_out;	/* TCPCB first byte out time */
	uint8_t		tlb_snd_scale:4, /* TCPCB snd_scale */
			tlb_rcv_scale:4; /* TCPCB rcv_scale */
	uint8_t		_pad[3];	/* Padding */
	/* Per-stack info */
	union tcp_log_stackspecific tlb_stackinfo;
#define	tlb_rack	tlb_stackinfo.u_rack

	/* The packet */
	uint32_t	tlb_len;	/* The packet's data length */
	struct tcphdr	tlb_th;		/* The TCP header */
	uint8_t		tlb_opts[TCP_MAXOLEN]; /* The TCP options */

	/* Verbose information (optional) */
	struct tcp_log_verbose tlb_verbose[0];
} ALIGN_TCP_LOG;

enum tcp_log_events {
	TCP_LOG_IN = 1,		/* Incoming packet                   1 */
	TCP_LOG_OUT,		/* Transmit (without other event)    2 */
	TCP_LOG_RTO,		/* Retransmit timeout                3 */
	TCP_LOG_SB_WAKE,	/* Awaken socket buffer              4 */
	TCP_LOG_BAD_RETRAN,	/* Detected bad retransmission       5 */
	TCP_LOG_PRR,		/* Doing PRR                         6 */
	TCP_LOG_REORDER,	/* Detected reorder                  7 */
	TCP_LOG_HPTS,		/* Hpts sending a packet             8 */
	BBR_LOG_BBRUPD,		/* We updated BBR info               9 */
	BBR_LOG_BBRSND,		/* We did a slot calculation and sending is done 10 */
	BBR_LOG_ACKCLEAR,	/* A ack clears all outstanding     11 */
	BBR_LOG_INQUEUE,	/* The tcb had a packet input to it 12 */
	BBR_LOG_TIMERSTAR,	/* Start a timer                    13 */
	BBR_LOG_TIMERCANC,	/* Cancel a timer                   14 */
	BBR_LOG_ENTREC,		/* Entered recovery                 15 */
	BBR_LOG_EXITREC,	/* Exited recovery                  16 */
	BBR_LOG_CWND,		/* Cwnd change                      17 */
	BBR_LOG_BWSAMP,		/* LT B/W sample has been made      18 */
	BBR_LOG_MSGSIZE,	/* We received a EMSGSIZE error     19 */
	BBR_LOG_BBRRTT,		/* BBR RTT is updated               20 */
	BBR_LOG_JUSTRET,	/* We just returned out of output   21 */
	BBR_LOG_STATE,		/* A BBR state change occurred      22 */
	BBR_LOG_PKT_EPOCH,      /* A BBR packet epoch occurred      23 */
	BBR_LOG_PERSIST,        /* BBR changed to/from a persists   24 */
	TCP_LOG_FLOWEND,        /* End of a flow                    25 */
	BBR_LOG_RTO,            /* BBR's timeout includes BBR info  26 */
	BBR_LOG_DOSEG_DONE,     /* hpts do_segment completes        27 */
	BBR_LOG_EXIT_GAIN,      /* hpts do_segment completes        28 */
	BBR_LOG_THRESH_CALC,    /* Doing threshold calculation      29 */
	TCP_LOG_MAPCHG,		/* Map Changes to the sendmap       30 */
	TCP_LOG_USERSEND, 	/* User level sends data            31 */
	BBR_RSM_CLEARED,	/* RSM cleared of ACK flags         32 */
	BBR_LOG_STATE_TARGET, 	/* Log of target at state           33 */
	BBR_LOG_TIME_EPOCH, 	/* A timed based Epoch occurred     34 */
	BBR_LOG_TO_PROCESS,	/* A to was processed               35 */
	BBR_LOG_BBRTSO,		/* TSO update                       36 */
	BBR_LOG_HPTSDIAG,	/* Hpts diag insert                 37 */
	BBR_LOG_LOWGAIN,	/* Low gain accounting              38 */
	BBR_LOG_PROGRESS,	/* Progress timer event             39 */
	TCP_LOG_SOCKET_OPT,	/* A socket option is set           40 */
	BBR_LOG_TIMERPREP,	/* A BBR var to debug out TLP issues  41 */
	BBR_LOG_ENOBUF_JMP,	/* We had a enobuf jump             42 */
	BBR_LOG_HPTSI_CALC,	/* calc the hptsi time              43 */
	BBR_LOG_RTT_SHRINKS,	/* We had a log reduction of rttProp 44 */
	BBR_LOG_BW_RED_EV,	/* B/W reduction events             45 */
	BBR_LOG_REDUCE,		/* old bbr log reduce for 4.1 and earlier 46*/
	TCP_LOG_RTT,		/* A rtt (in useconds) is being sampled and applied to the srtt algo 47 */
	BBR_LOG_SETTINGS_CHG,	/* Settings changed for loss response 48 */
	BBR_LOG_SRTT_GAIN_EVENT, /* SRTT gaining -- now not used    49 */
	TCP_LOG_REASS,		/* Reassembly buffer logging        50 */
	TCP_HDWR_PACE_SIZE,	/*  TCP pacing size set (rl and rack uses this)  51 */
	BBR_LOG_HDWR_PACE,	/* TCP Hardware pacing log          52 */
	BBR_LOG_TSTMP_VAL,	/* Temp debug timestamp validation  53 */
	TCP_LOG_CONNEND,	/* End of connection                54 */
	TCP_LOG_LRO,		/* LRO entry                        55 */
	TCP_SACK_FILTER_RES,	/* Results of SACK Filter           56 */
	TCP_SAD_DETECTION,	/* Sack Attack Detection            57 */
	TCP_TIMELY_WORK,	/* Logs regarding Timely CC tweaks  58 */
	TCP_LOG_USER_EVENT,	/* User space event data            59 */
	TCP_LOG_SENDFILE,	/* sendfile() logging for TCP connections 60 */
	TCP_LOG_HTTP_T,		/* logging of http request tracking 61 */
	TCP_LOG_ACCOUNTING,	/* Log of TCP Accounting data 62 */
	TCP_LOG_FSB,		/* FSB information 63 */
	RACK_DSACK_HANDLING,	/* Handling of DSACK in rack for reordering window 64 */
	TCP_HYSTART,		/* TCP Hystart logging 65 */
	TCP_CHG_QUERY,		/* Change query during fnc_init() 66 */
	TCP_RACK_LOG_COLLAPSE,	/* Window collapse by peer 67 */
	TCP_RACK_TP_TRIGGERED,	/* A rack tracepoint is triggered 68 */
	TCP_HYBRID_PACING_LOG,	/* Hybrid pacing log 69 */
	TCP_LOG_PRU,		/* TCP protocol user request        70 */
	TCP_LOG_END		/* End (keep at end)                71 */
};

enum tcp_log_states {
	TCP_LOG_STATE_RATIO_OFF = -2,	/* Log ratio evaluation yielded an OFF
					   result. Only used for tlb_logstate */
	TCP_LOG_STATE_CLEAR = -1,	/* Deactivate and clear tracing. Passed
					   to tcp_log_state_change() but never
					   stored in any logstate variable */
	TCP_LOG_STATE_OFF = 0,		/* Pause */

	/* Positively numbered states represent active logging modes */
	TCP_LOG_STATE_TAIL=1,		/* Keep the trailing events */
	TCP_LOG_STATE_HEAD=2,		/* Keep the leading events */
	TCP_LOG_STATE_HEAD_AUTO=3,	/* Keep the leading events, and
					   automatically dump them to the
					   device  */
	TCP_LOG_STATE_CONTINUAL=4,	/* Continually dump the data when full */
	TCP_LOG_STATE_TAIL_AUTO=5,	/* Keep the trailing events, and
					   automatically dump them when the
					   session ends */
	TCP_LOG_VIA_BBPOINTS=6		/* Log only if the BB point has been configured */
};

/* Use this if we don't know whether the operation succeeded. */
#define	ERRNO_UNK	(-1)

/*
 * If the user included dev/tcp_log/tcp_log_dev.h, then include our private
 * headers. Otherwise, there is no reason to pollute all the files with an
 * additional include.
 *
 * This structure is aligned to an 8-byte boundary to match the alignment
 * requirements of (struct tcp_log_buffer).
 */
#ifdef __tcp_log_dev_h__
struct tcp_log_header {
	struct tcp_log_common_header tlh_common;
#define	tlh_version	tlh_common.tlch_version
#define	tlh_type	tlh_common.tlch_type
#define	tlh_length	tlh_common.tlch_length
	struct in_endpoints	tlh_ie;
	struct timeval		tlh_offset;	/* Uptime -> UTC offset */
	char			tlh_id[TCP_LOG_ID_LEN];
	char			tlh_reason[TCP_LOG_REASON_LEN];
	char			tlh_tag[TCP_LOG_TAG_LEN];
	uint8_t		tlh_af;
	uint8_t		_pad[7];
} ALIGN_TCP_LOG;

#ifdef _KERNEL
struct tcp_log_dev_log_queue {
	struct tcp_log_dev_queue tldl_common;
	char			tldl_id[TCP_LOG_ID_LEN];
	char			tldl_reason[TCP_LOG_REASON_LEN];
	char			tldl_tag[TCP_LOG_TAG_LEN];
	struct in_endpoints	tldl_ie;
	struct tcp_log_stailq	tldl_entries;
	int			tldl_count;
	uint8_t			tldl_af;
};
#endif /* _KERNEL */
#endif /* __tcp_log_dev_h__ */

/*
 * Defined BBPOINTS that can be used
 * with TCP_LOG_VIA_BBPOINTS.
 */
#define TCP_BBPOINT_NONE		0
#define TCP_BBPOINT_REQ_LEVEL_LOGGING	1

/*********************/
/* TCP Trace points */
/*********************/
/*
 * TCP trace points are interesting points within
 * the TCP code that the author/debugger may want
 * to have BB logging enabled if we hit that point.
 * In order to enable a trace point you set the
 * sysctl var net.inet.tcp.bb.tp.number to
 * one of the numbers listed below. You also
 * must make sure net.inet.tcp.bb.tp.bbmode is
 * non-zero, the default is 4 for continuous tracing.
 * You also set in the number of connections you want
 * have get BB logs in net.inet.tcp.bb.tp.count.
 *
 * Count will decrement every time BB logging is assigned
 * to a connection that hit your tracepoint.
 *
 * You can enable all trace points by setting the number
 * to 0xffffffff. You can disable all trace points by
 * setting number to zero (or count to 0).
 *
 * Below are the enumerated list of tracepoints that
 * have currently been defined in the code. Add more
 * as you add a call to rack_trace_point(rack, <name>);
 * where <name> is defined below.
 */
#define TCP_TP_HWENOBUF		0x00000001	/* When we are doing hardware pacing and hit enobufs */
#define TCP_TP_ENOBUF		0x00000002	/* When we hit enobufs with software pacing */
#define TCP_TP_COLLAPSED_WND	0x00000003	/* When a peer to collapses its rwnd on us */
#define TCP_TP_COLLAPSED_RXT	0x00000004	/* When we actually retransmit a collapsed window rsm */
#define TCP_TP_HTTP_LOG_FAIL	0x00000005	/* We tried to allocate a HTTP log but had no space */
#define TCP_TP_RESET_RCV	0x00000006	/* Triggers when we receive a RST */
#define TCP_TP_EXCESS_RXT	0x00000007	/* When we get excess RXT's clamping the cwnd */
#define TCP_TP_SAD_TRIGGERED	0x00000008	/* Sack Attack Detection triggers */

#define TCP_TP_SAD_SUSPECT	0x0000000a	/* A sack has supicious information in it */

#ifdef _KERNEL

extern uint32_t tcp_trace_point_config;
extern uint32_t tcp_trace_point_bb_mode;
extern int32_t tcp_trace_point_count;

/*
 * Returns true if any sort of BB logging is enabled,
 * commonly used throughout the codebase.
 */
static inline int
tcp_bblogging_on(struct tcpcb *tp)
{
	if (tp->_t_logstate <= TCP_LOG_STATE_OFF)
		return (0);
	if (tp->_t_logstate == TCP_LOG_VIA_BBPOINTS)
		return (0);
	return (1);
}

/*
 * Returns true if we match a specific bbpoint when
 * in TCP_LOG_VIA_BBPOINTS, but also returns true
 * for all the other logging states.
 */
static inline int
tcp_bblogging_point_on(struct tcpcb *tp, uint8_t bbpoint)
{
	if (tp->_t_logstate <= TCP_LOG_STATE_OFF)
		return (0);
	if ((tp->_t_logstate == TCP_LOG_VIA_BBPOINTS) &&
	    (tp->_t_logpoint == bbpoint))
		return (1);
	else if (tp->_t_logstate == TCP_LOG_VIA_BBPOINTS)
		return (0);
	return (1);
}

static inline void
tcp_set_bblog_state(struct tcpcb *tp, uint8_t ls, uint8_t bbpoint)
{
	if ((ls == TCP_LOG_VIA_BBPOINTS) &&
	    (tp->_t_logstate <= TCP_LOG_STATE_OFF)){
		/*
		 * We don't allow a BBPOINTS set to override
		 * other types of BB logging set by other means such
		 * as the bb_ratio/bb_state URL parameters. In other
		 * words BBlogging must be *off* in order to turn on
		 * a BBpoint.
		 */
		tp->_t_logpoint = bbpoint;
		tp->_t_logstate = ls;
	} else if (ls != TCP_LOG_VIA_BBPOINTS) {
		tp->_t_logpoint = 0;
		if ((ls >= TCP_LOG_STATE_OFF) &&
		    (ls < TCP_LOG_VIA_BBPOINTS))
			tp->_t_logstate = ls;
	}
}

static inline uint32_t
tcp_get_bblog_state(struct tcpcb *tp)
{
	return (tp->_t_logstate);
}

static inline void
tcp_trace_point(struct tcpcb *tp, int num)
{
	if (((tcp_trace_point_config == num)  ||
	     (tcp_trace_point_config == 0xffffffff)) &&
	    (tcp_trace_point_bb_mode != 0) &&
	    (tcp_trace_point_count > 0) &&
	    (tcp_bblogging_on(tp) == 0)) {
		int res;
		res = atomic_fetchadd_int(&tcp_trace_point_count, -1);
		if (res > 0) {
			tcp_set_bblog_state(tp, tcp_trace_point_bb_mode, TCP_BBPOINT_NONE);
		} else {
			/* Loss a race assure its zero now */
			tcp_trace_point_count = 0;
		}
	}
}

#define	TCP_LOG_BUF_DEFAULT_SESSION_LIMIT	5000
#define	TCP_LOG_BUF_DEFAULT_GLOBAL_LIMIT	5000000

/*
 * TCP_LOG_EVENT_VERBOSE: The same as TCP_LOG_EVENT, except it always
 * tries to record verbose information.
 */
#define	TCP_LOG_EVENT_VERBOSE(tp, th, rxbuf, txbuf, eventid, errornum, len, stackinfo, th_hostorder, tv) \
	do {								\
		if (tcp_bblogging_on(tp)) \
			tcp_log_event(tp, th, rxbuf, txbuf, eventid,	\
			    errornum, len, stackinfo, th_hostorder,	\
			    tp->t_output_caller, __func__, __LINE__, tv);\
	} while (0)

/*
 * TCP_LOG_EVENT: This is a macro so we can capture function/line
 * information when needed. You can use the macro when you are not
 * doing a lot of prep in the stack specific information i.e. you
 * don't add extras (stackinfo). If you are adding extras which
 * means filling out a stack variable instead use the tcp_log_event()
 * function but enclose the call to the log (and all the setup) in a
 * if (tcp_bblogging_on(tp)) {
 *   ... setup and logging call ...
 * }
 *
 * Always use the macro tcp_bblogging_on() since sometimes the defintions
 * do change.
 *
 * BBlogging also supports the concept of a BBpoint. The idea behind this
 * is that when you set a specific BBpoint on and turn the logging into
 * the BBpoint mode (TCP_LOG_VIA_BBPOINTS) you will be defining very very
 * few of these points to come out. The point is specific to a code you
 * want tied to that one BB logging. This allows you to turn on a much broader
 * scale set of limited logging on more connections without overwhelming the
 * I/O system with too much BBlogs. This of course means you need to be quite
 * careful on how many BBlogs go with each point, but you can have multiple points
 * only one of which is active at a time.
 *
 * To define a point you add it above under the define for TCP_BBPOINT_NONE (which
 * is the default i.e. no point is defined. You then, for your point use the
 * tcp_bblogging_point_on(struct tcpcb *tp, uint8_t bbpoint) inline to enclose
 * your call to tcp_log_event.  Do not use one of the TCP_LOGGING macros else
 * your point will never come out. You specify your defined point in the bbpoint
 * side of the inline. An example of this you can find in rack where the
 * TCP_BBPOINT_REQ_LEVEL_LOGGING is used. There a specific set of logs are generated
 * for each http request that rack is tracking.
 *
 * When turning on BB logging use the inline:
 * tcp_set_bblog_state(struct tcpcb *tp, uint8_t ls, uint8_t bbpoint)
 * the ls field is the logging state TCP_LOG_STATE_CONTINUAL etc. The
 * bbpoint field is ignored unless the ls field is set to TCP_LOG_VIA_BBPOINTS.
 * Currently there is only a socket option that turns on the non-BBPOINT
 * logging.
 *
 * Prototype:
 * TCP_LOG_EVENT(struct tcpcb *tp, struct tcphdr *th, struct sockbuf *rxbuf,
 *     struct sockbuf *txbuf, uint8_t eventid, int errornum,
 *     union tcp_log_stackspecific *stackinfo)
 *
 * tp is mandatory and must be write locked.
 * th is optional; if present, it will appear in the record.
 * rxbuf and txbuf are optional; if present, they will appear in the record.
 * eventid is mandatory.
 * errornum is mandatory (it indicates the success or failure of the
 *     operation associated with the event).
 * len indicates the length of the packet. If no packet, use 0.
 * stackinfo is optional; if present, it will appear in the record.
 */
struct tcpcb;
#ifdef TCP_LOG_FORCEVERBOSE
#define	TCP_LOG_EVENT	TCP_LOG_EVENT_VERBOSE
#else
#define	TCP_LOG_EVENT(tp, th, rxbuf, txbuf, eventid, errornum, len, stackinfo, th_hostorder) \
	do {								\
		if (tcp_log_verbose)					\
			TCP_LOG_EVENT_VERBOSE(tp, th, rxbuf, txbuf,	\
			    eventid, errornum, len, stackinfo,		\
			    th_hostorder, NULL);			\
		else if (tcp_bblogging_on(tp))				\
			tcp_log_event(tp, th, rxbuf, txbuf, eventid,	\
			    errornum, len, stackinfo, th_hostorder,	\
			    NULL, NULL, 0, NULL);			\
	} while (0)
#endif /* TCP_LOG_FORCEVERBOSE */
#define	TCP_LOG_EVENTP(tp, th, rxbuf, txbuf, eventid, errornum, len, stackinfo, th_hostorder, tv) \
	do {								\
		if (tcp_bblogging_on(tp))				\
			tcp_log_event(tp, th, rxbuf, txbuf, eventid,	\
			    errornum, len, stackinfo, th_hostorder,	\
			    NULL, NULL, 0, tv);				\
	} while (0)

#ifdef TCP_BLACKBOX
extern bool tcp_log_verbose;
void tcp_log_drain(struct tcpcb *tp);
int tcp_log_dump_tp_logbuf(struct tcpcb *tp, char *reason, int how, bool force);
void tcp_log_dump_tp_bucket_logbufs(struct tcpcb *tp, char *reason);
struct tcp_log_buffer *tcp_log_event(struct tcpcb *tp, struct tcphdr *th, struct sockbuf *rxbuf,
    struct sockbuf *txbuf, uint8_t eventid, int errornum, uint32_t len,
    union tcp_log_stackspecific *stackinfo, int th_hostorder,
    const char *output_caller, const char *func, int line, const struct timeval *tv);
size_t tcp_log_get_id(struct tcpcb *tp, char *buf);
size_t tcp_log_get_tag(struct tcpcb *tp, char *buf);
u_int tcp_log_get_id_cnt(struct tcpcb *tp);
int tcp_log_getlogbuf(struct sockopt *sopt, struct tcpcb *tp);
void tcp_log_init(void);
int tcp_log_set_id(struct tcpcb *tp, char *id);
int tcp_log_set_tag(struct tcpcb *tp, char *tag);
int tcp_log_state_change(struct tcpcb *tp, int state);
void tcp_log_tcpcbinit(struct tcpcb *tp);
void tcp_log_tcpcbfini(struct tcpcb *tp);
void tcp_log_flowend(struct tcpcb *tp);
void tcp_log_sendfile(struct socket *so, off_t offset, size_t nbytes,
    int flags);
int tcp_log_apply_ratio(struct tcpcb *tp, int ratio);
#else /* !TCP_BLACKBOX */
#define tcp_log_verbose	(false)

static inline struct tcp_log_buffer *
tcp_log_event(struct tcpcb *tp, struct tcphdr *th, struct sockbuf *rxbuf,
    struct sockbuf *txbuf, uint8_t eventid, int errornum, uint32_t len,
    union tcp_log_stackspecific *stackinfo, int th_hostorder,
    const char *output_caller, const char *func, int line,
    const struct timeval *tv)
{

	return (NULL);
}
#endif /* TCP_BLACKBOX */

#endif	/* _KERNEL */
#endif	/* __tcp_log_buf_h__ */