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