1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2009-2010
5 * 	Swinburne University of Technology, Melbourne, Australia
6 * Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
7 * All rights reserved.
8 *
9 * This software was developed at the Centre for Advanced Internet
10 * Architectures, Swinburne University of Technology, by David Hayes, made
11 * possible in part by a grant from the Cisco University Research Program Fund
12 * at Community Foundation Silicon Valley.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * $FreeBSD$
36 */
37
38/*
39 * The ERTT (Enhanced Round Trip Time) Khelp module calculates an estimate of
40 * the instantaneous TCP RTT which, for example, is used by delay-based
41 * congestion control schemes. When the module is loaded, ERTT data is
42 * calculated for each active TCP connection and encapsulated within a
43 * "struct ertt".
44 *
45 * This software was first released in 2010 by David Hayes and Lawrence Stewart
46 * whilst working on the NewTCP research project at Swinburne University of
47 * Technology's Centre for Advanced Internet Architectures, Melbourne,
48 * Australia, which was made possible in part by a grant from the Cisco
49 * University Research Program Fund at Community Foundation Silicon Valley.
50 * Testing and development was further assisted by a grant from the FreeBSD
51 * Foundation. More details are available at:
52 *   http://caia.swin.edu.au/urp/newtcp/
53 */
54
55#ifndef	_NETINET_KHELP_H_ERTT_
56#define	_NETINET_KHELP_H_ERTT_
57
58struct txseginfo;
59
60/* Structure used as the ertt data block. */
61struct ertt {
62	/* Information about transmitted segments to aid in RTT calculation. */
63	TAILQ_HEAD(txseginfo_head, txseginfo) txsegi_q;
64	/* Bytes TX so far in marked RTT. */
65	long		bytes_tx_in_rtt;
66	/* Final version of above. */
67	long		bytes_tx_in_marked_rtt;
68	/* cwnd for marked RTT. */
69	unsigned long	marked_snd_cwnd;
70	/* Per-packet measured RTT. */
71	int		rtt;
72	/* Maximum RTT measured. */
73	int		maxrtt;
74	/* Minimum RTT measured. */
75	int		minrtt;
76	/* Guess if the receiver is using delayed ack. */
77	int		dlyack_rx;
78	/* Keep track of inconsistencies in packet timestamps. */
79	int		timestamp_errors;
80	/* RTT for a marked packet. */
81	int		markedpkt_rtt;
82	/* Flags to signal conditions between hook function calls. */
83	uint32_t	flags;
84};
85
86/* Flags for struct ertt. */
87#define	ERTT_NEW_MEASUREMENT		0x01
88#define	ERTT_MEASUREMENT_IN_PROGRESS	0x02
89#define	ERTT_TSO_DISABLED		0x04
90
91#endif /* _NETINET_KHELP_H_ERTT_ */
92