xref: /linux/include/net/sctp/tsnmap.h (revision 2da68a77) 
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  */
36 struct 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 
79 struct sctp_tsnmap_iter {
80 	__u32 start;
81 };
82 
83 /* Initialize a block of memory as a tsnmap.  */
84 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *, __u16 len,
85 				     __u32 initial_tsn, gfp_t gfp);
86 
87 void 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  */
95 int sctp_tsnmap_check(const struct sctp_tsnmap *, __u32 tsn);
96 
97 /* Mark this TSN as seen.  */
98 int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn,
99 		     struct sctp_transport *trans);
100 
101 /* Mark this TSN and all lower as seen. */
102 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn);
103 
104 /* Retrieve the Cumulative TSN ACK Point.  */
105 static 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.  */
111 static 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? */
117 static 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. */
123 static 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?  */
137 static 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  */
145 static 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.  */
152 void sctp_tsnmap_renege(struct sctp_tsnmap *, __u32 tsn);
153 
154 /* Is there a gap in the TSN map? */
155 int sctp_tsnmap_has_gap(const struct sctp_tsnmap *);
156 
157 #endif /* __sctp_tsnmap_h__ */
158