kernel-ark/net/sctp/tsnmap.c
Vlad Yasevich 60c778b259 [SCTP]: Stop claiming that this is a "reference implementation"
I was notified by Randy Stewart that lksctp claims to be
"the reference implementation".  First of all, "the
refrence implementation" was the original implementation
of SCTP in usersapce written ty Randy and a few others.
Second, after looking at the definiton of 'reference implementation',
we don't really meet the requirements.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
2008-02-05 10:59:07 -05:00

419 lines
10 KiB
C

/* 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 functions manipulate sctp tsn mapping array.
*
* This SCTP 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.
*
* This SCTP 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)) {
__u16 start, end;
sctp_tsnmap_iter_init(map, &iter);
while (sctp_tsnmap_next_gap_ack(map, &iter,
&start,
&end)) {
map->gabs[gabs].start = htons(start);
map->gabs[gabs].end = htons(end);
gabs++;
if (gabs >= SCTP_MAX_GABS)
break;
}
}
return gabs;
}