1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/* SCTP kernel implementation
3 * (C) Copyright IBM Corp. 2001, 2004
4 * Copyright (c) 1999-2000 Cisco, Inc.
5 * Copyright (c) 1999-2001 Motorola, Inc.
6 * Copyright (c) 2001 Intel Corp.
7 *
8 * This file is part of the SCTP kernel implementation
9 *
10 * These are the definitions needed for the tsnmap type.  The tsnmap is used
11 * to track out of order TSNs received.
12 *
13 * Please send any bug reports or fixes you make to the
14 * email address(es):
15 *    lksctp developers <linux-sctp@vger.kernel.org>
16 *
17 * Written or modified by:
18 *   Jon Grimm             <jgrimm@us.ibm.com>
19 *   La Monte H.P. Yarroll <piggy@acm.org>
20 *   Karl Knutson          <karl@athena.chicago.il.us>
21 *   Sridhar Samudrala     <sri@us.ibm.com>
22 */
23#include <net/sctp/constants.h>
24
25#ifndef __sctp_tsnmap_h__
26#define __sctp_tsnmap_h__
27
28/* RFC 2960 12.2 Parameters necessary per association (i.e. the TCB)
29 * Mapping  An array of bits or bytes indicating which out of
30 * Array    order TSN's have been received (relative to the
31 *          Last Rcvd TSN). If no gaps exist, i.e. no out of
32 *          order packets have been received, this array
33 *          will be set to all zero. This structure may be
34 *          in the form of a circular buffer or bit array.
35 */
36struct sctp_tsnmap {
37	/* This array counts the number of chunks with each TSN.
38	 * It points at one of the two buffers with which we will
39	 * ping-pong between.
40	 */
41	unsigned long *tsn_map;
42
43	/* This is the TSN at tsn_map[0].  */
44	__u32 base_tsn;
45
46	/* Last Rcvd   : This is the last TSN received in
47	 * TSN	       : sequence. This value is set initially by
48	 *             : taking the peer's Initial TSN, received in
49	 *             : the INIT or INIT ACK chunk, and subtracting
50	 *             : one from it.
51	 *
52	 * Throughout most of the specification this is called the
53	 * "Cumulative TSN ACK Point".  In this case, we
54	 * ignore the advice in 12.2 in favour of the term
55	 * used in the bulk of the text.
56	 */
57	__u32 cumulative_tsn_ack_point;
58
59	/* This is the highest TSN we've marked.  */
60	__u32 max_tsn_seen;
61
62	/* This is the minimum number of TSNs we can track.  This corresponds
63	 * to the size of tsn_map.   Note: the overflow_map allows us to
64	 * potentially track more than this quantity.
65	 */
66	__u16 len;
67
68	/* Data chunks pending receipt. used by SCTP_STATUS sockopt */
69	__u16 pending_data;
70
71	/* Record duplicate TSNs here.  We clear this after
72	 * every SACK.  Store up to SCTP_MAX_DUP_TSNS worth of
73	 * information.
74	 */
75	__u16 num_dup_tsns;
76	__be32 dup_tsns[SCTP_MAX_DUP_TSNS];
77};
78
79struct sctp_tsnmap_iter {
80	__u32 start;
81};
82
83/* Initialize a block of memory as a tsnmap.  */
84struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *, __u16 len,
85				     __u32 initial_tsn, gfp_t gfp);
86
87void sctp_tsnmap_free(struct sctp_tsnmap *map);
88
89/* Test the tracking state of this TSN.
90 * Returns:
91 *   0 if the TSN has not yet been seen
92 *  >0 if the TSN has been seen (duplicate)
93 *  <0 if the TSN is invalid (too large to track)
94 */
95int sctp_tsnmap_check(const struct sctp_tsnmap *, __u32 tsn);
96
97/* Mark this TSN as seen.  */
98int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn,
99		     struct sctp_transport *trans);
100
101/* Mark this TSN and all lower as seen. */
102void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn);
103
104/* Retrieve the Cumulative TSN ACK Point.  */
105static inline __u32 sctp_tsnmap_get_ctsn(const struct sctp_tsnmap *map)
106{
107	return map->cumulative_tsn_ack_point;
108}
109
110/* Retrieve the highest TSN we've seen.  */
111static inline __u32 sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap *map)
112{
113	return map->max_tsn_seen;
114}
115
116/* How many duplicate TSNs are stored? */
117static inline __u16 sctp_tsnmap_num_dups(struct sctp_tsnmap *map)
118{
119	return map->num_dup_tsns;
120}
121
122/* Return pointer to duplicate tsn array as needed by SACK. */
123static inline __be32 *sctp_tsnmap_get_dups(struct sctp_tsnmap *map)
124{
125	map->num_dup_tsns = 0;
126	return map->dup_tsns;
127}
128
129/* How many gap ack blocks do we have recorded? */
130__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
131			   struct sctp_gap_ack_block *gabs);
132
133/* Refresh the count on pending data. */
134__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map);
135
136/* Is there a gap in the TSN map?  */
137static inline int sctp_tsnmap_has_gap(const struct sctp_tsnmap *map)
138{
139	return map->cumulative_tsn_ack_point != map->max_tsn_seen;
140}
141
142/* Mark a duplicate TSN.  Note:  limit the storage of duplicate TSN
143 * information.
144 */
145static inline void sctp_tsnmap_mark_dup(struct sctp_tsnmap *map, __u32 tsn)
146{
147	if (map->num_dup_tsns < SCTP_MAX_DUP_TSNS)
148		map->dup_tsns[map->num_dup_tsns++] = htonl(tsn);
149}
150
151/* Renege a TSN that was seen.  */
152void sctp_tsnmap_renege(struct sctp_tsnmap *, __u32 tsn);
153
154/* Is there a gap in the TSN map? */
155int sctp_tsnmap_has_gap(const struct sctp_tsnmap *);
156
157#endif /* __sctp_tsnmap_h__ */
158