patch-2.4.23 linux-2.4.23/net/sctp/tsnmap.c

• Lines: 407
• Date: 2003-11-28 10:26:21.000000000 -0800
• Orig file: linux-2.4.22/net/sctp/tsnmap.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.22/net/sctp/tsnmap.c linux-2.4.23/net/sctp/tsnmap.c
@@ -0,0 +1,406 @@
+/* SCTP kernel reference Implementation
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001 International Business Machines, Corp.
+ * 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>
+ *
+ * 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_update_pending_data(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);
+
+/* Create a new sctp_tsnmap.
+ * Allocate room to store at least 'len' contiguous TSNs.
+ */
+struct sctp_tsnmap *sctp_tsnmap_new(__u16 len, __u32 initial_tsn, int gfp)
+{
+	struct sctp_tsnmap *retval;
+
+	retval = kmalloc(sizeof(struct sctp_tsnmap) +
+			 sctp_tsnmap_storage_size(len), gfp);
+	if (!retval)
+		goto fail;
+
+	if (!sctp_tsnmap_init(retval, len, initial_tsn))
+		goto fail_map;
+	retval->malloced = 1;
+	return retval;
+
+fail_map:
+	kfree(retval);
+fail:
+	return NULL;
+}
+
+/* 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->pending_data = 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;
+}
+
+/* Is there a gap in the TSN map?  */
+int sctp_tsnmap_has_gap(const struct sctp_tsnmap *map)
+{
+	int has_gap;
+
+	has_gap = (map->cumulative_tsn_ack_point != map->max_tsn_seen);
+	return has_gap;
+}
+
+/* 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);
+}
+
+void sctp_tsnmap_report_dup(struct sctp_tsnmap *map, __u32 tsn)
+{
+}
+
+/* Retrieve the Cumulative TSN Ack Point. */
+__u32 sctp_tsnmap_get_ctsn(const struct sctp_tsnmap *map)
+{
+	return map->cumulative_tsn_ack_point;
+}
+
+/* Retrieve the highest TSN we've seen.  */
+__u32 sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap *map)
+{
+	return map->max_tsn_seen;
+}
+
+/* Dispose of a tsnmap.  */
+void sctp_tsnmap_free(struct sctp_tsnmap *map)
+{
+	if (map->malloced)
+		kfree(map);
+}
+
+/* Initialize a Gap Ack Block iterator from memory being provided.  */
+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.
+ */
+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;
+
+	/* 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;
+}
+
+/********************************************************************
+ * 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. */
+	sctp_tsnmap_update_pending_data(map);
+}
+
+static void sctp_tsnmap_update_pending_data(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:
+	map->pending_data = 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.
+	 */
+
+	/* 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;
+}