1 files changed, 417 insertions, 0 deletions

diff --git a/net/sctp/tsnmap.c b/net/sctp/tsnmap.c
new file mode 100644
index 000000000000..ac4fae161bc7
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+++ 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;
+}