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DTRACE_SCTP(4)		    Kernel Interfaces Manual		DTRACE_SCTP(4)

NAME
       dtrace_sctp  --	a  DTrace  provider  for tracing events	related	to the
       sctp(4) protocol

SYNOPSIS
       sctp:cwnd::init(uint32_t, uint32_t, uintptr_t, int, int);

       sctp:cwnd::ack(uint32_t,	uint32_t, uintptr_t, int, int);

       sctp:cwnd::rttvar(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t);

       sctp:cwnd::rttstep(uint64_t, uint64_t, uint64_t,	uint64_t, uint64_t);

       sctp:cwnd::fr(uint32_t, uint32_t, uintptr_t, int, int);

       sctp:cwnd::to(uint32_t, uint32_t, uintptr_t, int, int);

       sctp:cwnd::bl(uint32_t, uint32_t, uintptr_t, int, int);

       sctp:cwnd::ecn(uint32_t,	uint32_t, uintptr_t, int, int);

       sctp:cwnd::pd(uint32_t, uint32_t, uintptr_t, int, int);

       sctp:rwnd:assoc:val(uint32_t, uint32_t, int, int);

       sctp:flightsize:net:val(uint32_t, uint32_t, uintptr_t, int, int);

       sctp:flightsize:assoc:val(uint32_t, uint32_t, int, int);

       sctp:::receive(pktinfo_t	*, csinfo_t  *,	 ipinfo_t  *,  sctpsinfo_t  *,
	   sctpinfo_t *);

       sctp:::send(pktinfo_t   *,  csinfo_t  *,	 ipinfo_t  *,  sctpsinfo_t  *,
	   sctpinfo_t *);

       sctp:::state-change(void	*, csinfo_t *, void *, sctpsinfo_t *, void  *,
	   sctplsinfo_t	*);

DESCRIPTION
       The  DTrace  sctp  provider allows users	to trace events	in the sctp(4)
       protocol	implementation.	 This provider is similar to the  dtrace_ip(4)
       and  dtrace_udp(4)  providers,  but additionally	contains probes	corre-
       sponding	to protocol events at a	level higher than packet reception and
       transmission.

       The sctp:cwnd::() probes	track changes in the congestion	 window	 on  a
       netp.   The  sctp:rwnd::()  probes track	changes	in the receiver	window
       for an assoc.  The sctp:flightsize:net:val() probe  tracks  changes  in
       the  flight  size on a net or assoc and the sctp:flightsize:assoc:val()
       probe provides the total	flight version.

       The arguments of	all  sctp  probes  except  for	sctp:cwnd::rtt*()  and
       sctp::assoc:val() are the Vtag for this end, the	port number of the lo-
       cal  side,  the pointer to struct sctp_nets *changing, the old value of
       the cwnd, and the new value of the cwnd.

       The arguments of	sctp:::val() are  similar  to  the  above  except  the
       fourth argument is the up/down amount.

       The  sctp:cwnd::rtt*()  probe  arguments	 are  a	bitmap of Vtag << 32 |
       localport << 16 | remoteport, a bitmap of obw | nbw, a bitmap of	 bwrtt
       |  newrtt,  flight,  and	 a  bitmap  of	(cwnd  <<  32) | point << 16 |
       retval(0/1).

       The sctp:cwnd::init() probe fires when a	remotely-initiated active SCTP
       open succeeds.  At this point the new connection	is in the  ESTABLISHED
       state,  and  the	probe arguments	expose the headers associated with the
       final ACK of the	four-way handshake.

       The sctp:::send() and sctp:::receive() probes fire when the host	 sends
       or  receives  an	 SCTP packet, respectively.  As	with the dtrace_udp(4)
       provider, sctp probes fire only for packets sent	by  or	to  the	 local
       host;  forwarded	packets	are handled in the IP layer and	are only visi-
       ble to the dtrace_ip(4) provider.

       The sctp:::state-change() probe fires upon local	SCTP association state
       transitions.  Its first,	third and fifth	arguments are currently	always
       NULL.  Its last argument	describes the from-state  in  the  transition,
       and the to-state	can be obtained	from args[3]->sctps_state.

FILES
       /usr/lib/dtrace/sctp.d  DTrace  type and	translator definitions for the
			       sctp provider.

EXAMPLES
       A script	that logs SCTP packets in real time:

	     #pragma D option quiet
	     #pragma D option switchrate=10hz

	     dtrace:::BEGIN
	     {
		     printf(" %3s %15s:%-5s	 %15s:%-5s\n", "CPU",
			 "LADDR", "LPORT", "RADDR", "RPORT");
	     }

	     sctp:::send
	     {
		     printf(" %3d %16s:%-5d -> %16s:%-5d\n", cpu,
			 args[2]->ip_saddr, args[4]->sctp_sport,
			 args[2]->ip_daddr, args[4]->sctp_dport);
	     }

	     sctp:::receive
	     {
		     printf(" %3d %16s:%-5d <- %16s:%-5d\n", cpu,
			 args[2]->ip_daddr, args[4]->sctp_dport,
			 args[2]->ip_saddr, args[4]->sctp_sport);
	     }
       A script	that logs SCTP association state changes as they occur:

	     #pragma D option quiet
	     #pragma D option switchrate=10

	     int last[int];

	     dtrace:::BEGIN
	     {
		     printf(" %3s %12s	%-25s	 %-25s\n",
			 "CPU",	"DELTA(us)", "OLD", "NEW");
	     }

	     sctp:::state-change
	     / last[args[1]->cs_cid] /
	     {
		     this->elapsed = (timestamp	- last[args[1]->cs_cid]) / 1000;
		     printf(" %3d %12d	%-25s -> %-25s\n", cpu,	this->elapsed,
			 sctp_state_string[args[5]->sctps_state],
			 sctp_state_string[args[3]->sctps_state]);
		     last[args[1]->cs_cid] = timestamp;
	     }

	     sctp:::state-change
	     / last[args[1]->cs_cid] ==	0 /
	     {
		     printf(" %3d %12s	%-25s -> %-25s\n", cpu,	"-",
			 sctp_state_string[args[5]->sctps_state],
			 sctp_state_string[args[3]->sctps_state]);
		     last[args[1]->cs_cid] = timestamp;
	     }

COMPATIBILITY
       The sctp:::send(), sctp:::receive(), and	 sctp:::state-change()	probes
       are compatible with the sctp provider in	Solaris.  All other probes are
       only available in FreeBSD.

SEE ALSO
       dtrace(1),  dtrace_ip(4),  dtrace_udp(4),  dtrace_udplite(4),  sctp(4),
       SDT(9)

AUTHORS
       This manual page	was written by Devin Teske <dteske@FreeBSD.org>.

FreeBSD	14.3			 June 29, 2023			DTRACE_SCTP(4)

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