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418 lines
10 KiB
418 lines
10 KiB
/* SCTP kernel implementation
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* (C) Copyright IBM Corp. 2001, 2004
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* Copyright (c) 1999-2000 Cisco, Inc.
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* Copyright (c) 1999-2001 Motorola, Inc.
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* Copyright (c) 2001 Intel Corp.
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*
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* This file is part of the SCTP kernel implementation
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*
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* These functions manipulate sctp tsn mapping array.
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*
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* This SCTP implementation is free software;
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* you can redistribute it and/or modify it under the terms of
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* the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This SCTP implementation is distributed in the hope that it
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* will be useful, but WITHOUT ANY WARRANTY; without even the implied
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* ************************
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU CC; see the file COPYING. If not, write to
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* the Free Software Foundation, 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*
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* Please send any bug reports or fixes you make to the
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* email address(es):
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* lksctp developers <lksctp-developers@lists.sourceforge.net>
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*
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* Or submit a bug report through the following website:
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* http://www.sf.net/projects/lksctp
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*
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* Written or modified by:
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* La Monte H.P. Yarroll <piggy@acm.org>
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* Jon Grimm <jgrimm@us.ibm.com>
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* Karl Knutson <karl@athena.chicago.il.us>
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* Sridhar Samudrala <sri@us.ibm.com>
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*
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* Any bugs reported given to us we will try to fix... any fixes shared will
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* be incorporated into the next SCTP release.
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*/
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#include <linux/types.h>
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#include <net/sctp/sctp.h>
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#include <net/sctp/sm.h>
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static void sctp_tsnmap_update(struct sctp_tsnmap *map);
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static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
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__u16 len, __u16 base,
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int *started, __u16 *start,
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int *ended, __u16 *end);
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/* Initialize a block of memory as a tsnmap. */
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struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
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__u32 initial_tsn)
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{
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map->tsn_map = map->raw_map;
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map->overflow_map = map->tsn_map + len;
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map->len = len;
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/* Clear out a TSN ack status. */
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memset(map->tsn_map, 0x00, map->len + map->len);
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/* Keep track of TSNs represented by tsn_map. */
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map->base_tsn = initial_tsn;
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map->overflow_tsn = initial_tsn + map->len;
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map->cumulative_tsn_ack_point = initial_tsn - 1;
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map->max_tsn_seen = map->cumulative_tsn_ack_point;
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map->malloced = 0;
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map->num_dup_tsns = 0;
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return map;
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}
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/* Test the tracking state of this TSN.
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* Returns:
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* 0 if the TSN has not yet been seen
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* >0 if the TSN has been seen (duplicate)
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* <0 if the TSN is invalid (too large to track)
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*/
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int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
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{
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__s32 gap;
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int dup;
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/* Calculate the index into the mapping arrays. */
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gap = tsn - map->base_tsn;
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/* Verify that we can hold this TSN. */
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if (gap >= (/* base */ map->len + /* overflow */ map->len)) {
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dup = -1;
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goto out;
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}
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/* Honk if we've already seen this TSN.
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* We have three cases:
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* 1. The TSN is ancient or belongs to a previous tsn_map.
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* 2. The TSN is already marked in the tsn_map.
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* 3. The TSN is already marked in the tsn_map_overflow.
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*/
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if (gap < 0 ||
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(gap < map->len && map->tsn_map[gap]) ||
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(gap >= map->len && map->overflow_map[gap - map->len]))
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dup = 1;
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else
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dup = 0;
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out:
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return dup;
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}
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/* Mark this TSN as seen. */
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void sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
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{
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__s32 gap;
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/* Vacuously mark any TSN which precedes the map base or
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* exceeds the end of the map.
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*/
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if (TSN_lt(tsn, map->base_tsn))
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return;
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if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
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return;
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/* Bump the max. */
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if (TSN_lt(map->max_tsn_seen, tsn))
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map->max_tsn_seen = tsn;
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/* Assert: TSN is in range. */
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gap = tsn - map->base_tsn;
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/* Mark the TSN as received. */
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if (gap < map->len)
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map->tsn_map[gap]++;
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else
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map->overflow_map[gap - map->len]++;
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/* Go fixup any internal TSN mapping variables including
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* cumulative_tsn_ack_point.
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*/
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sctp_tsnmap_update(map);
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}
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/* Initialize a Gap Ack Block iterator from memory being provided. */
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SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
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struct sctp_tsnmap_iter *iter)
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{
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/* Only start looking one past the Cumulative TSN Ack Point. */
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iter->start = map->cumulative_tsn_ack_point + 1;
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}
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/* Get the next Gap Ack Blocks. Returns 0 if there was not another block
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* to get.
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*/
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SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
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struct sctp_tsnmap_iter *iter,
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__u16 *start, __u16 *end)
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{
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int started, ended;
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__u16 start_, end_, offset;
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/* We haven't found a gap yet. */
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started = ended = 0;
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/* If there are no more gap acks possible, get out fast. */
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if (TSN_lte(map->max_tsn_seen, iter->start))
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return 0;
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/* Search the first mapping array. */
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if (iter->start - map->base_tsn < map->len) {
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offset = iter->start - map->base_tsn;
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sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 0,
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&started, &start_, &ended, &end_);
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}
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/* Do we need to check the overflow map? */
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if (!ended) {
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/* Fix up where we'd like to start searching in the
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* overflow map.
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*/
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if (iter->start - map->base_tsn < map->len)
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offset = 0;
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else
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offset = iter->start - map->base_tsn - map->len;
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/* Search the overflow map. */
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sctp_tsnmap_find_gap_ack(map->overflow_map,
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offset,
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map->len,
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map->len,
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&started, &start_,
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&ended, &end_);
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}
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/* The Gap Ack Block happens to end at the end of the
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* overflow map.
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*/
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if (started && !ended) {
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ended++;
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end_ = map->len + map->len - 1;
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}
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/* If we found a Gap Ack Block, return the start and end and
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* bump the iterator forward.
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*/
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if (ended) {
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/* Fix up the start and end based on the
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* Cumulative TSN Ack offset into the map.
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*/
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int gap = map->cumulative_tsn_ack_point -
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map->base_tsn;
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*start = start_ - gap;
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*end = end_ - gap;
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/* Move the iterator forward. */
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iter->start = map->cumulative_tsn_ack_point + *end + 1;
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}
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return ended;
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}
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/* Mark this and any lower TSN as seen. */
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void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
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{
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__s32 gap;
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/* Vacuously mark any TSN which precedes the map base or
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* exceeds the end of the map.
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*/
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if (TSN_lt(tsn, map->base_tsn))
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return;
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if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
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return;
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/* Bump the max. */
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if (TSN_lt(map->max_tsn_seen, tsn))
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map->max_tsn_seen = tsn;
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/* Assert: TSN is in range. */
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gap = tsn - map->base_tsn + 1;
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/* Mark the TSNs as received. */
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if (gap <= map->len)
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memset(map->tsn_map, 0x01, gap);
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else {
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memset(map->tsn_map, 0x01, map->len);
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memset(map->overflow_map, 0x01, (gap - map->len));
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}
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/* Go fixup any internal TSN mapping variables including
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* cumulative_tsn_ack_point.
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*/
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sctp_tsnmap_update(map);
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}
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/********************************************************************
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* 2nd Level Abstractions
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********************************************************************/
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/* This private helper function updates the tsnmap buffers and
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* the Cumulative TSN Ack Point.
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*/
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static void sctp_tsnmap_update(struct sctp_tsnmap *map)
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{
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__u32 ctsn;
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ctsn = map->cumulative_tsn_ack_point;
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do {
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ctsn++;
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if (ctsn == map->overflow_tsn) {
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/* Now tsn_map must have been all '1's,
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* so we swap the map and check the overflow table
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*/
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__u8 *tmp = map->tsn_map;
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memset(tmp, 0, map->len);
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map->tsn_map = map->overflow_map;
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map->overflow_map = tmp;
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/* Update the tsn_map boundaries. */
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map->base_tsn += map->len;
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map->overflow_tsn += map->len;
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}
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} while (map->tsn_map[ctsn - map->base_tsn]);
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map->cumulative_tsn_ack_point = ctsn - 1; /* Back up one. */
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}
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/* How many data chunks are we missing from our peer?
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*/
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__u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
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{
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__u32 cum_tsn = map->cumulative_tsn_ack_point;
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__u32 max_tsn = map->max_tsn_seen;
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__u32 base_tsn = map->base_tsn;
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__u16 pending_data;
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__s32 gap, start, end, i;
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pending_data = max_tsn - cum_tsn;
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gap = max_tsn - base_tsn;
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if (gap <= 0 || gap >= (map->len + map->len))
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goto out;
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start = ((cum_tsn >= base_tsn) ? (cum_tsn - base_tsn + 1) : 0);
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end = ((gap > map->len ) ? map->len : gap + 1);
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for (i = start; i < end; i++) {
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if (map->tsn_map[i])
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pending_data--;
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}
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if (gap >= map->len) {
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start = 0;
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end = gap - map->len + 1;
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for (i = start; i < end; i++) {
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if (map->overflow_map[i])
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pending_data--;
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}
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}
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out:
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return pending_data;
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}
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/* This is a private helper for finding Gap Ack Blocks. It searches a
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* single array for the start and end of a Gap Ack Block.
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*
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* The flags "started" and "ended" tell is if we found the beginning
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* or (respectively) the end of a Gap Ack Block.
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*/
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static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
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__u16 len, __u16 base,
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int *started, __u16 *start,
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int *ended, __u16 *end)
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{
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int i = off;
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/* Look through the entire array, but break out
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* early if we have found the end of the Gap Ack Block.
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*/
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/* Also, stop looking past the maximum TSN seen. */
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/* Look for the start. */
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if (!(*started)) {
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for (; i < len; i++) {
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if (map[i]) {
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(*started)++;
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*start = base + i;
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break;
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}
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}
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}
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/* Look for the end. */
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if (*started) {
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/* We have found the start, let's find the
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* end. If we find the end, break out.
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*/
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for (; i < len; i++) {
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if (!map[i]) {
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(*ended)++;
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*end = base + i - 1;
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break;
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}
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}
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}
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}
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/* Renege that we have seen a TSN. */
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void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
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{
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__s32 gap;
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if (TSN_lt(tsn, map->base_tsn))
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return;
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if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
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return;
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/* Assert: TSN is in range. */
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gap = tsn - map->base_tsn;
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/* Pretend we never saw the TSN. */
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if (gap < map->len)
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map->tsn_map[gap] = 0;
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else
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map->overflow_map[gap - map->len] = 0;
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}
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/* How many gap ack blocks do we have recorded? */
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__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map)
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{
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struct sctp_tsnmap_iter iter;
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int gabs = 0;
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/* Refresh the gap ack information. */
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if (sctp_tsnmap_has_gap(map)) {
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__u16 start, end;
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sctp_tsnmap_iter_init(map, &iter);
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while (sctp_tsnmap_next_gap_ack(map, &iter,
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&start,
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&end)) {
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map->gabs[gabs].start = htons(start);
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map->gabs[gabs].end = htons(end);
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gabs++;
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if (gabs >= SCTP_MAX_GABS)
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break;
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}
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}
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return gabs;
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}
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