/* 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 <linux/bitmap.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(unsigned long *map, __u16 off, __u16 len, __u16 *start, __u16 *end); static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap); /* Initialize a block of memory as a tsnmap. */ struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len, __u32 initial_tsn, gfp_t gfp) { if (!map->tsn_map) { map->tsn_map = kzalloc(len>>3, gfp); if (map->tsn_map == NULL) return NULL; map->len = len; } else { bitmap_zero(map->tsn_map, map->len); } /* Keep track of TSNs represented by tsn_map. */ map->base_tsn = initial_tsn; map->cumulative_tsn_ack_point = initial_tsn - 1; map->max_tsn_seen = map->cumulative_tsn_ack_point; map->num_dup_tsns = 0; return map; } void sctp_tsnmap_free(struct sctp_tsnmap *map) { map->len = 0; kfree(map->tsn_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) { u32 gap; /* Check to see if this is an old TSN */ if (TSN_lte(tsn, map->cumulative_tsn_ack_point)) return 1; /* Verify that we can hold this TSN and that it will not * overlfow our map */ if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) return -1; /* Calculate the index into the mapping arrays. */ gap = tsn - map->base_tsn; /* Check to see if TSN has already been recorded. */ if (gap < map->len && test_bit(gap, map->tsn_map)) return 1; else return 0; } /* Mark this TSN as seen. */ int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn) { u16 gap; if (TSN_lt(tsn, map->base_tsn)) return 0; gap = tsn - map->base_tsn; if (gap >= map->len && !sctp_tsnmap_grow(map, gap)) return -ENOMEM; if (!sctp_tsnmap_has_gap(map) && gap == 0) { /* In this case the map has no gaps and the tsn we are * recording is the next expected tsn. We don't touch * the map but simply bump the values. */ map->max_tsn_seen++; map->cumulative_tsn_ack_point++; map->base_tsn++; } else { /* Either we already have a gap, or about to record a gap, so * have work to do. * * Bump the max. */ if (TSN_lt(map->max_tsn_seen, tsn)) map->max_tsn_seen = tsn; /* Mark the TSN as received. */ set_bit(gap, map->tsn_map); /* Go fixup any internal TSN mapping variables including * cumulative_tsn_ack_point. */ sctp_tsnmap_update(map); } return 0; } /* 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 ended = 0; __u16 start_ = 0, end_ = 0, offset; /* If there are no more gap acks possible, get out fast. */ if (TSN_lte(map->max_tsn_seen, iter->start)) return 0; offset = iter->start - map->base_tsn; sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, &start_, &end_); /* The Gap Ack Block happens to end at the end of the map. */ if (start_ && !end_) end_ = map->len - 1; /* If we found a Gap Ack Block, return the start and end and * bump the iterator forward. */ if (end_) { /* Fix up the start and end based on the * Cumulative TSN Ack which is always 1 behind base. */ *start = start_ + 1; *end = end_ + 1; /* Move the iterator forward. */ iter->start = map->cumulative_tsn_ack_point + *end + 1; ended = 1; } return ended; } /* Mark this and any lower TSN as seen. */ void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn) { u32 gap; if (TSN_lt(tsn, map->base_tsn)) return; if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) return; /* Bump the max. */ if (TSN_lt(map->max_tsn_seen, tsn)) map->max_tsn_seen = tsn; gap = tsn - map->base_tsn + 1; map->base_tsn += gap; map->cumulative_tsn_ack_point += gap; if (gap >= map->len) { /* If our gap is larger then the map size, just * zero out the map. */ bitmap_zero(map->tsn_map, map->len); } else { /* If the gap is smaller than the map size, * shift the map by 'gap' bits and update further. */ bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len); 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) { u16 len; unsigned long zero_bit; len = map->max_tsn_seen - map->cumulative_tsn_ack_point; zero_bit = find_first_zero_bit(map->tsn_map, len); if (!zero_bit) return; /* The first 0-bit is bit 0. nothing to do */ map->base_tsn += zero_bit; map->cumulative_tsn_ack_point += zero_bit; bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len); } /* 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; u32 gap, i; pending_data = max_tsn - cum_tsn; gap = max_tsn - base_tsn; if (gap == 0 || gap >= map->len) goto out; for (i = 0; i < gap+1; i++) { if (test_bit(i, map->tsn_map)) 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(unsigned long *map, __u16 off, __u16 len, __u16 *start, __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. */ i = find_next_bit(map, len, off); if (i < len) *start = i; /* Look for the end. */ if (*start) { /* We have found the start, let's find the * end. If we find the end, break out. */ i = find_next_zero_bit(map, len, i); if (i < len) *end = i - 1; } } /* Renege that we have seen a TSN. */ void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn) { u32 gap; if (TSN_lt(tsn, map->base_tsn)) return; /* Assert: TSN is in range. */ if (!TSN_lt(tsn, map->base_tsn + map->len)) return; gap = tsn - map->base_tsn; /* Pretend we never saw the TSN. */ clear_bit(gap, map->tsn_map); } /* How many gap ack blocks do we have recorded? */ __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map, struct sctp_gap_ack_block *gabs) { struct sctp_tsnmap_iter iter; int ngaps = 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)) { gabs[ngaps].start = htons(start); gabs[ngaps].end = htons(end); ngaps++; if (ngaps >= SCTP_MAX_GABS) break; } } return ngaps; } static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap) { unsigned long *new; unsigned long inc; u16 len; if (gap >= SCTP_TSN_MAP_SIZE) return 0; inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT; len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE); new = kzalloc(len>>3, GFP_ATOMIC); if (!new) return 0; bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn); kfree(map->tsn_map); map->tsn_map = new; map->len = len; return 1; }