102 lines
2.8 KiB
C
102 lines
2.8 KiB
C
/*
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* Copyright (C) 2006-2012 B.A.T.M.A.N. contributors:
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*
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* Simon Wunderlich, Marek Lindner
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*
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*/
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#include "main.h"
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#include "bitarray.h"
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#include <linux/bitops.h>
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/* shift the packet array by n places. */
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static void bat_bitmap_shift_left(unsigned long *seq_bits, int32_t n)
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{
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if (n <= 0 || n >= TQ_LOCAL_WINDOW_SIZE)
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return;
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bitmap_shift_left(seq_bits, seq_bits, n, TQ_LOCAL_WINDOW_SIZE);
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}
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/* receive and process one packet within the sequence number window.
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*
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* returns:
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* 1 if the window was moved (either new or very old)
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* 0 if the window was not moved/shifted.
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*/
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int bit_get_packet(void *priv, unsigned long *seq_bits,
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int32_t seq_num_diff, int set_mark)
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{
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struct bat_priv *bat_priv = priv;
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/* sequence number is slightly older. We already got a sequence number
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* higher than this one, so we just mark it. */
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if ((seq_num_diff <= 0) && (seq_num_diff > -TQ_LOCAL_WINDOW_SIZE)) {
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if (set_mark)
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bat_set_bit(seq_bits, -seq_num_diff);
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return 0;
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}
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/* sequence number is slightly newer, so we shift the window and
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* set the mark if required */
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if ((seq_num_diff > 0) && (seq_num_diff < TQ_LOCAL_WINDOW_SIZE)) {
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bat_bitmap_shift_left(seq_bits, seq_num_diff);
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if (set_mark)
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bat_set_bit(seq_bits, 0);
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return 1;
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}
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/* sequence number is much newer, probably missed a lot of packets */
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if ((seq_num_diff >= TQ_LOCAL_WINDOW_SIZE) &&
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(seq_num_diff < EXPECTED_SEQNO_RANGE)) {
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bat_dbg(DBG_BATMAN, bat_priv,
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"We missed a lot of packets (%i) !\n",
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seq_num_diff - 1);
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bitmap_zero(seq_bits, TQ_LOCAL_WINDOW_SIZE);
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if (set_mark)
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bat_set_bit(seq_bits, 0);
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return 1;
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}
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/* received a much older packet. The other host either restarted
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* or the old packet got delayed somewhere in the network. The
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* packet should be dropped without calling this function if the
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* seqno window is protected. */
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if ((seq_num_diff <= -TQ_LOCAL_WINDOW_SIZE) ||
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(seq_num_diff >= EXPECTED_SEQNO_RANGE)) {
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bat_dbg(DBG_BATMAN, bat_priv,
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"Other host probably restarted!\n");
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bitmap_zero(seq_bits, TQ_LOCAL_WINDOW_SIZE);
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if (set_mark)
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bat_set_bit(seq_bits, 0);
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return 1;
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}
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/* never reached */
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return 0;
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}
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