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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* SCTP kernel implementation
* (C) Copyright IBM Corp. 2001, 2004
* Copyright (c) 1999-2000 Cisco, Inc.
* Copyright (c) 1999-2001 Motorola, Inc.
* Copyright (c) 2001 Intel Corp.
* This file is part of the SCTP kernel implementation
* These are the definitions needed for the tsnmap type. The tsnmap is used
* to track out of order TSNs received.
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <>
* Written or modified by:
* Jon Grimm <>
* La Monte H.P. Yarroll <>
* Karl Knutson <>
* Sridhar Samudrala <>
#include <net/sctp/constants.h>
#ifndef __sctp_tsnmap_h__
#define __sctp_tsnmap_h__
/* RFC 2960 12.2 Parameters necessary per association (i.e. the TCB)
* Mapping An array of bits or bytes indicating which out of
* Array order TSN's have been received (relative to the
* Last Rcvd TSN). If no gaps exist, i.e. no out of
* order packets have been received, this array
* will be set to all zero. This structure may be
* in the form of a circular buffer or bit array.
struct sctp_tsnmap {
/* This array counts the number of chunks with each TSN.
* It points at one of the two buffers with which we will
* ping-pong between.
unsigned long *tsn_map;
/* This is the TSN at tsn_map[0]. */
__u32 base_tsn;
/* Last Rcvd : This is the last TSN received in
* TSN : sequence. This value is set initially by
* : taking the peer's Initial TSN, received in
* : the INIT or INIT ACK chunk, and subtracting
* : one from it.
* Throughout most of the specification this is called the
* "Cumulative TSN ACK Point". In this case, we
* ignore the advice in 12.2 in favour of the term
* used in the bulk of the text.
__u32 cumulative_tsn_ack_point;
/* This is the highest TSN we've marked. */
__u32 max_tsn_seen;
/* This is the minimum number of TSNs we can track. This corresponds
* to the size of tsn_map. Note: the overflow_map allows us to
* potentially track more than this quantity.
__u16 len;
/* Data chunks pending receipt. used by SCTP_STATUS sockopt */
__u16 pending_data;
/* Record duplicate TSNs here. We clear this after
* every SACK. Store up to SCTP_MAX_DUP_TSNS worth of
* information.
__u16 num_dup_tsns;
__be32 dup_tsns[SCTP_MAX_DUP_TSNS];
struct sctp_tsnmap_iter {
__u32 start;
/* Initialize a block of memory as a tsnmap. */
struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *, __u16 len,
__u32 initial_tsn, gfp_t gfp);
void sctp_tsnmap_free(struct sctp_tsnmap *map);
/* Test the tracking state of this TSN.
* Returns:
* 0 if the TSN has not yet been seen
* >0 if the TSN has been seen (duplicate)
* <0 if the TSN is invalid (too large to track)
int sctp_tsnmap_check(const struct sctp_tsnmap *, __u32 tsn);
/* Mark this TSN as seen. */
int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn,
struct sctp_transport *trans);
/* Mark this TSN and all lower as seen. */
void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn);
/* Retrieve the Cumulative TSN ACK Point. */
static inline __u32 sctp_tsnmap_get_ctsn(const struct sctp_tsnmap *map)
return map->cumulative_tsn_ack_point;
/* Retrieve the highest TSN we've seen. */
static inline __u32 sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap *map)
return map->max_tsn_seen;
/* How many duplicate TSNs are stored? */
static inline __u16 sctp_tsnmap_num_dups(struct sctp_tsnmap *map)
return map->num_dup_tsns;
/* Return pointer to duplicate tsn array as needed by SACK. */
static inline __be32 *sctp_tsnmap_get_dups(struct sctp_tsnmap *map)
map->num_dup_tsns = 0;
return map->dup_tsns;
/* How many gap ack blocks do we have recorded? */
__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
struct sctp_gap_ack_block *gabs);
/* Refresh the count on pending data. */
__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map);
/* Is there a gap in the TSN map? */
static inline int sctp_tsnmap_has_gap(const struct sctp_tsnmap *map)
return map->cumulative_tsn_ack_point != map->max_tsn_seen;
/* Mark a duplicate TSN. Note: limit the storage of duplicate TSN
* information.
static inline void sctp_tsnmap_mark_dup(struct sctp_tsnmap *map, __u32 tsn)
if (map->num_dup_tsns < SCTP_MAX_DUP_TSNS)
map->dup_tsns[map->num_dup_tsns++] = htonl(tsn);
/* Renege a TSN that was seen. */
void sctp_tsnmap_renege(struct sctp_tsnmap *, __u32 tsn);
/* Is there a gap in the TSN map? */
int sctp_tsnmap_has_gap(const struct sctp_tsnmap *);
#endif /* __sctp_tsnmap_h__ */