1/* SCTP kernel implementation
2 * (C) Copyright IBM Corp. 2001, 2004
3 * Copyright (c) 1999-2000 Cisco, Inc.
4 * Copyright (c) 1999-2001 Motorola, Inc.
5 * Copyright (c) 2001 Intel Corp.
6 *
7 * This file is part of the SCTP kernel implementation
8 *
9 * These are the definitions needed for the tsnmap type.  The tsnmap is used
10 * to track out of order TSNs received.
11 *
12 * This SCTP implementation is free software;
13 * you can redistribute it and/or modify it under the terms of
14 * the GNU General Public License as published by
15 * the Free Software Foundation; either version 2, or (at your option)
16 * any later version.
17 *
18 * This SCTP implementation is distributed in the hope that it
19 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
20 *                 ************************
21 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22 * See the GNU General Public License for more details.
23 *
24 * You should have received a copy of the GNU General Public License
25 * along with GNU CC; see the file COPYING.  If not, see
26 * <http://www.gnu.org/licenses/>.
27 *
28 * Please send any bug reports or fixes you make to the
29 * email address(es):
30 *    lksctp developers <linux-sctp@vger.kernel.org>
31 *
32 * Written or modified by:
33 *   Jon Grimm             <jgrimm@us.ibm.com>
34 *   La Monte H.P. Yarroll <piggy@acm.org>
35 *   Karl Knutson          <karl@athena.chicago.il.us>
36 *   Sridhar Samudrala     <sri@us.ibm.com>
37 */
38#include <net/sctp/constants.h>
39
40#ifndef __sctp_tsnmap_h__
41#define __sctp_tsnmap_h__
42
43/* RFC 2960 12.2 Parameters necessary per association (i.e. the TCB)
44 * Mapping  An array of bits or bytes indicating which out of
45 * Array    order TSN's have been received (relative to the
46 *          Last Rcvd TSN). If no gaps exist, i.e. no out of
47 *          order packets have been received, this array
48 *          will be set to all zero. This structure may be
49 *          in the form of a circular buffer or bit array.
50 */
51struct sctp_tsnmap {
52	/* This array counts the number of chunks with each TSN.
53	 * It points at one of the two buffers with which we will
54	 * ping-pong between.
55	 */
56	unsigned long *tsn_map;
57
58	/* This is the TSN at tsn_map[0].  */
59	__u32 base_tsn;
60
61	/* Last Rcvd   : This is the last TSN received in
62	 * TSN	       : sequence. This value is set initially by
63	 *             : taking the peer's Initial TSN, received in
64	 *             : the INIT or INIT ACK chunk, and subtracting
65	 *             : one from it.
66	 *
67	 * Throughout most of the specification this is called the
68	 * "Cumulative TSN ACK Point".  In this case, we
69	 * ignore the advice in 12.2 in favour of the term
70	 * used in the bulk of the text.
71	 */
72	__u32 cumulative_tsn_ack_point;
73
74	/* This is the highest TSN we've marked.  */
75	__u32 max_tsn_seen;
76
77	/* This is the minimum number of TSNs we can track.  This corresponds
78	 * to the size of tsn_map.   Note: the overflow_map allows us to
79	 * potentially track more than this quantity.
80	 */
81	__u16 len;
82
83	/* Data chunks pending receipt. used by SCTP_STATUS sockopt */
84	__u16 pending_data;
85
86	/* Record duplicate TSNs here.  We clear this after
87	 * every SACK.  Store up to SCTP_MAX_DUP_TSNS worth of
88	 * information.
89	 */
90	__u16 num_dup_tsns;
91	__be32 dup_tsns[SCTP_MAX_DUP_TSNS];
92};
93
94struct sctp_tsnmap_iter {
95	__u32 start;
96};
97
98/* Initialize a block of memory as a tsnmap.  */
99struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *, __u16 len,
100				     __u32 initial_tsn, gfp_t gfp);
101
102void sctp_tsnmap_free(struct sctp_tsnmap *map);
103
104/* Test the tracking state of this TSN.
105 * Returns:
106 *   0 if the TSN has not yet been seen
107 *  >0 if the TSN has been seen (duplicate)
108 *  <0 if the TSN is invalid (too large to track)
109 */
110int sctp_tsnmap_check(const struct sctp_tsnmap *, __u32 tsn);
111
112/* Mark this TSN as seen.  */
113int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn,
114		     struct sctp_transport *trans);
115
116/* Mark this TSN and all lower as seen. */
117void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn);
118
119/* Retrieve the Cumulative TSN ACK Point.  */
120static inline __u32 sctp_tsnmap_get_ctsn(const struct sctp_tsnmap *map)
121{
122	return map->cumulative_tsn_ack_point;
123}
124
125/* Retrieve the highest TSN we've seen.  */
126static inline __u32 sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap *map)
127{
128	return map->max_tsn_seen;
129}
130
131/* How many duplicate TSNs are stored? */
132static inline __u16 sctp_tsnmap_num_dups(struct sctp_tsnmap *map)
133{
134	return map->num_dup_tsns;
135}
136
137/* Return pointer to duplicate tsn array as needed by SACK. */
138static inline __be32 *sctp_tsnmap_get_dups(struct sctp_tsnmap *map)
139{
140	map->num_dup_tsns = 0;
141	return map->dup_tsns;
142}
143
144/* How many gap ack blocks do we have recorded? */
145__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
146			   struct sctp_gap_ack_block *gabs);
147
148/* Refresh the count on pending data. */
149__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map);
150
151/* Is there a gap in the TSN map?  */
152static inline int sctp_tsnmap_has_gap(const struct sctp_tsnmap *map)
153{
154	return map->cumulative_tsn_ack_point != map->max_tsn_seen;
155}
156
157/* Mark a duplicate TSN.  Note:  limit the storage of duplicate TSN
158 * information.
159 */
160static inline void sctp_tsnmap_mark_dup(struct sctp_tsnmap *map, __u32 tsn)
161{
162	if (map->num_dup_tsns < SCTP_MAX_DUP_TSNS)
163		map->dup_tsns[map->num_dup_tsns++] = htonl(tsn);
164}
165
166/* Renege a TSN that was seen.  */
167void sctp_tsnmap_renege(struct sctp_tsnmap *, __u32 tsn);
168
169/* Is there a gap in the TSN map? */
170int sctp_tsnmap_has_gap(const struct sctp_tsnmap *);
171
172#endif /* __sctp_tsnmap_h__ */
173