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, write to
26  * the Free Software Foundation, 59 Temple Place - Suite 330,
27  * Boston, MA 02111-1307, USA.
28  *
29  * Please send any bug reports or fixes you make to the
30  * email address(es):
31  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
32  *
33  * Or submit a bug report through the following website:
34  *    http://www.sf.net/projects/lksctp
35  *
36  * Written or modified by:
37  *   Jon Grimm             <jgrimm@us.ibm.com>
38  *   La Monte H.P. Yarroll <piggy@acm.org>
39  *   Karl Knutson          <karl@athena.chicago.il.us>
40  *   Sridhar Samudrala     <sri@us.ibm.com>
41  *
42  * Any bugs reported given to us we will try to fix... any fixes shared will
43  * be incorporated into the next SCTP release.
44  */
45 #include <net/sctp/constants.h>
46 
47 #ifndef __sctp_tsnmap_h__
48 #define __sctp_tsnmap_h__
49 
50 /* RFC 2960 12.2 Parameters necessary per association (i.e. the TCB)
51  * Mapping  An array of bits or bytes indicating which out of
52  * Array    order TSN's have been received (relative to the
53  *          Last Rcvd TSN). If no gaps exist, i.e. no out of
54  *          order packets have been received, this array
55  *          will be set to all zero. This structure may be
56  *          in the form of a circular buffer or bit array.
57  */
58 struct sctp_tsnmap {
59 	/* This array counts the number of chunks with each TSN.
60 	 * It points at one of the two buffers with which we will
61 	 * ping-pong between.
62 	 */
63 	unsigned long *tsn_map;
64 
65 	/* This is the TSN at tsn_map[0].  */
66 	__u32 base_tsn;
67 
68 	/* Last Rcvd   : This is the last TSN received in
69 	 * TSN	       : sequence. This value is set initially by
70 	 *             : taking the peer's Initial TSN, received in
71 	 *             : the INIT or INIT ACK chunk, and subtracting
72 	 *             : one from it.
73 	 *
74 	 * Throughout most of the specification this is called the
75 	 * "Cumulative TSN ACK Point".  In this case, we
76 	 * ignore the advice in 12.2 in favour of the term
77 	 * used in the bulk of the text.
78 	 */
79 	__u32 cumulative_tsn_ack_point;
80 
81 	/* This is the highest TSN we've marked.  */
82 	__u32 max_tsn_seen;
83 
84 	/* This is the minimum number of TSNs we can track.  This corresponds
85 	 * to the size of tsn_map.   Note: the overflow_map allows us to
86 	 * potentially track more than this quantity.
87 	 */
88 	__u16 len;
89 
90 	/* Data chunks pending receipt. used by SCTP_STATUS sockopt */
91 	__u16 pending_data;
92 
93 	/* Record duplicate TSNs here.  We clear this after
94 	 * every SACK.  Store up to SCTP_MAX_DUP_TSNS worth of
95 	 * information.
96 	 */
97 	__u16 num_dup_tsns;
98 	__be32 dup_tsns[SCTP_MAX_DUP_TSNS];
99 };
100 
101 struct sctp_tsnmap_iter {
102 	__u32 start;
103 };
104 
105 /* Initialize a block of memory as a tsnmap.  */
106 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *, __u16 len,
107 				     __u32 initial_tsn, gfp_t gfp);
108 
109 void sctp_tsnmap_free(struct sctp_tsnmap *map);
110 
111 /* Test the tracking state of this TSN.
112  * Returns:
113  *   0 if the TSN has not yet been seen
114  *  >0 if the TSN has been seen (duplicate)
115  *  <0 if the TSN is invalid (too large to track)
116  */
117 int sctp_tsnmap_check(const struct sctp_tsnmap *, __u32 tsn);
118 
119 /* Mark this TSN as seen.  */
120 int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn);
121 
122 /* Mark this TSN and all lower as seen. */
123 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn);
124 
125 /* Retrieve the Cumulative TSN ACK Point.  */
sctp_tsnmap_get_ctsn(const struct sctp_tsnmap * map)126 static inline __u32 sctp_tsnmap_get_ctsn(const struct sctp_tsnmap *map)
127 {
128 	return map->cumulative_tsn_ack_point;
129 }
130 
131 /* Retrieve the highest TSN we've seen.  */
sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap * map)132 static inline __u32 sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap *map)
133 {
134 	return map->max_tsn_seen;
135 }
136 
137 /* How many duplicate TSNs are stored? */
sctp_tsnmap_num_dups(struct sctp_tsnmap * map)138 static inline __u16 sctp_tsnmap_num_dups(struct sctp_tsnmap *map)
139 {
140 	return map->num_dup_tsns;
141 }
142 
143 /* Return pointer to duplicate tsn array as needed by SACK. */
sctp_tsnmap_get_dups(struct sctp_tsnmap * map)144 static inline __be32 *sctp_tsnmap_get_dups(struct sctp_tsnmap *map)
145 {
146 	map->num_dup_tsns = 0;
147 	return map->dup_tsns;
148 }
149 
150 /* How many gap ack blocks do we have recorded? */
151 __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
152 			   struct sctp_gap_ack_block *gabs);
153 
154 /* Refresh the count on pending data. */
155 __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map);
156 
157 /* Is there a gap in the TSN map?  */
sctp_tsnmap_has_gap(const struct sctp_tsnmap * map)158 static inline int sctp_tsnmap_has_gap(const struct sctp_tsnmap *map)
159 {
160 	return map->cumulative_tsn_ack_point != map->max_tsn_seen;
161 }
162 
163 /* Mark a duplicate TSN.  Note:  limit the storage of duplicate TSN
164  * information.
165  */
sctp_tsnmap_mark_dup(struct sctp_tsnmap * map,__u32 tsn)166 static inline void sctp_tsnmap_mark_dup(struct sctp_tsnmap *map, __u32 tsn)
167 {
168 	if (map->num_dup_tsns < SCTP_MAX_DUP_TSNS)
169 		map->dup_tsns[map->num_dup_tsns++] = htonl(tsn);
170 }
171 
172 /* Renege a TSN that was seen.  */
173 void sctp_tsnmap_renege(struct sctp_tsnmap *, __u32 tsn);
174 
175 /* Is there a gap in the TSN map? */
176 int sctp_tsnmap_has_gap(const struct sctp_tsnmap *);
177 
178 #endif /* __sctp_tsnmap_h__ */
179