| 1 | /* Copyright (C) 2006-2016 B.A.T.M.A.N. contributors: |
| 2 | * |
| 3 | * Simon Wunderlich, Marek Lindner |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of version 2 of the GNU General Public |
| 7 | * License as published by the Free Software Foundation. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, but |
| 10 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | * General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
| 16 | */ |
| 17 | |
| 18 | #include "bitarray.h" |
| 19 | #include "main.h" |
| 20 | |
| 21 | #include <linux/bitmap.h> |
| 22 | |
| 23 | /* shift the packet array by n places. */ |
| 24 | static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n) |
| 25 | { |
| 26 | if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) |
| 27 | return; |
| 28 | |
| 29 | bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE); |
| 30 | } |
| 31 | |
| 32 | /** |
| 33 | * batadv_bit_get_packet - receive and process one packet within the sequence |
| 34 | * number window |
| 35 | * @priv: the bat priv with all the soft interface information |
| 36 | * @seq_bits: pointer to the sequence number receive packet |
| 37 | * @seq_num_diff: difference between the current/received sequence number and |
| 38 | * the last sequence number |
| 39 | * @set_mark: whether this packet should be marked in seq_bits |
| 40 | * |
| 41 | * Return: 1 if the window was moved (either new or very old), |
| 42 | * 0 if the window was not moved/shifted. |
| 43 | */ |
| 44 | int batadv_bit_get_packet(void *priv, unsigned long *seq_bits, s32 seq_num_diff, |
| 45 | int set_mark) |
| 46 | { |
| 47 | struct batadv_priv *bat_priv = priv; |
| 48 | |
| 49 | /* sequence number is slightly older. We already got a sequence number |
| 50 | * higher than this one, so we just mark it. |
| 51 | */ |
| 52 | if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) { |
| 53 | if (set_mark) |
| 54 | batadv_set_bit(seq_bits, -seq_num_diff); |
| 55 | return 0; |
| 56 | } |
| 57 | |
| 58 | /* sequence number is slightly newer, so we shift the window and |
| 59 | * set the mark if required |
| 60 | */ |
| 61 | if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) { |
| 62 | batadv_bitmap_shift_left(seq_bits, seq_num_diff); |
| 63 | |
| 64 | if (set_mark) |
| 65 | batadv_set_bit(seq_bits, 0); |
| 66 | return 1; |
| 67 | } |
| 68 | |
| 69 | /* sequence number is much newer, probably missed a lot of packets */ |
| 70 | if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && |
| 71 | seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { |
| 72 | batadv_dbg(BATADV_DBG_BATMAN, bat_priv, |
| 73 | "We missed a lot of packets (%i) !\n", |
| 74 | seq_num_diff - 1); |
| 75 | bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); |
| 76 | if (set_mark) |
| 77 | batadv_set_bit(seq_bits, 0); |
| 78 | return 1; |
| 79 | } |
| 80 | |
| 81 | /* received a much older packet. The other host either restarted |
| 82 | * or the old packet got delayed somewhere in the network. The |
| 83 | * packet should be dropped without calling this function if the |
| 84 | * seqno window is protected. |
| 85 | * |
| 86 | * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE |
| 87 | * or |
| 88 | * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE |
| 89 | */ |
| 90 | batadv_dbg(BATADV_DBG_BATMAN, bat_priv, |
| 91 | "Other host probably restarted!\n"); |
| 92 | |
| 93 | bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); |
| 94 | if (set_mark) |
| 95 | batadv_set_bit(seq_bits, 0); |
| 96 | |
| 97 | return 1; |
| 98 | } |