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net/batman-adv/bitarray.c
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/* Copyright (C) 2006-2014 B.A.T.M.A.N. contributors: |
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* * Simon Wunderlich, Marek Lindner * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. * * This program 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 |
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* along with this program; if not, see <http://www.gnu.org/licenses/>. |
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*/ #include "main.h" #include "bitarray.h" #include <linux/bitops.h> |
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/* shift the packet array by n places. */ |
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static void batadv_bitmap_shift_left(unsigned long *seq_bits, int32_t n) |
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{ |
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if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) |
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return; |
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bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE); |
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} |
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/* receive and process one packet within the sequence number window. * * returns: * 1 if the window was moved (either new or very old) * 0 if the window was not moved/shifted. */ |
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int batadv_bit_get_packet(void *priv, unsigned long *seq_bits, int32_t seq_num_diff, int set_mark) |
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{ |
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struct batadv_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 > -BATADV_TQ_LOCAL_WINDOW_SIZE) { |
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if (set_mark) |
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batadv_set_bit(seq_bits, -seq_num_diff); |
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return 0; } /* 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 < BATADV_TQ_LOCAL_WINDOW_SIZE) { |
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batadv_bitmap_shift_left(seq_bits, seq_num_diff); |
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if (set_mark) |
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batadv_set_bit(seq_bits, 0); |
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return 1; } /* sequence number is much newer, probably missed a lot of packets */ |
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if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { |
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batadv_dbg(BATADV_DBG_BATMAN, bat_priv, |
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"We missed a lot of packets (%i) ! ", seq_num_diff - 1); |
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bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); |
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if (set_mark) |
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batadv_set_bit(seq_bits, 0); |
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return 1; } /* received a much older packet. The other host either restarted * or the old packet got delayed somewhere in the network. The * packet should be dropped without calling this function if the |
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* seqno window is protected. |
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* * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE * or * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE |
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*/ |
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batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Other host probably restarted! "); |
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bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); if (set_mark) batadv_set_bit(seq_bits, 0); |
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return 1; |
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} |