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-rw-r--r--net/sctp/tsnmap.c417
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diff --git a/net/sctp/tsnmap.c b/net/sctp/tsnmap.c
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+/* 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;
+}
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