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9f6446c7 | 1 | /* Copyright (C) 2006-2015 B.A.T.M.A.N. contributors: |
c6c8fea2 SE |
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 | |
ebf38fb7 | 15 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
c6c8fea2 SE |
16 | */ |
17 | ||
18 | #include "main.h" | |
19 | #include "bitarray.h" | |
20 | ||
21 | #include <linux/bitops.h> | |
22 | ||
c6c8fea2 | 23 | /* shift the packet array by n places. */ |
0f5f9322 | 24 | static void batadv_bitmap_shift_left(unsigned long *seq_bits, int32_t n) |
c6c8fea2 | 25 | { |
42d0b044 | 26 | if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) |
c6c8fea2 SE |
27 | return; |
28 | ||
42d0b044 | 29 | bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE); |
c6c8fea2 SE |
30 | } |
31 | ||
c6c8fea2 SE |
32 | /* receive and process one packet within the sequence number window. |
33 | * | |
34 | * returns: | |
35 | * 1 if the window was moved (either new or very old) | |
36 | * 0 if the window was not moved/shifted. | |
37 | */ | |
0f5f9322 SE |
38 | int batadv_bit_get_packet(void *priv, unsigned long *seq_bits, |
39 | int32_t seq_num_diff, int set_mark) | |
c6c8fea2 | 40 | { |
56303d34 | 41 | struct batadv_priv *bat_priv = priv; |
c6c8fea2 SE |
42 | |
43 | /* sequence number is slightly older. We already got a sequence number | |
9cfc7bd6 SE |
44 | * higher than this one, so we just mark it. |
45 | */ | |
42d0b044 | 46 | if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) { |
c6c8fea2 | 47 | if (set_mark) |
9b4a1159 | 48 | batadv_set_bit(seq_bits, -seq_num_diff); |
c6c8fea2 SE |
49 | return 0; |
50 | } | |
51 | ||
52 | /* sequence number is slightly newer, so we shift the window and | |
9cfc7bd6 SE |
53 | * set the mark if required |
54 | */ | |
42d0b044 | 55 | if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) { |
0f5f9322 | 56 | batadv_bitmap_shift_left(seq_bits, seq_num_diff); |
c6c8fea2 SE |
57 | |
58 | if (set_mark) | |
9b4a1159 | 59 | batadv_set_bit(seq_bits, 0); |
c6c8fea2 SE |
60 | return 1; |
61 | } | |
62 | ||
63 | /* sequence number is much newer, probably missed a lot of packets */ | |
42d0b044 SE |
64 | if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && |
65 | seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { | |
39c75a51 | 66 | batadv_dbg(BATADV_DBG_BATMAN, bat_priv, |
1eda58bf SE |
67 | "We missed a lot of packets (%i) !\n", |
68 | seq_num_diff - 1); | |
42d0b044 | 69 | bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); |
c6c8fea2 | 70 | if (set_mark) |
9b4a1159 | 71 | batadv_set_bit(seq_bits, 0); |
c6c8fea2 SE |
72 | return 1; |
73 | } | |
74 | ||
75 | /* received a much older packet. The other host either restarted | |
76 | * or the old packet got delayed somewhere in the network. The | |
77 | * packet should be dropped without calling this function if the | |
9cfc7bd6 | 78 | * seqno window is protected. |
8e7c15d6 SE |
79 | * |
80 | * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE | |
81 | * or | |
82 | * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE | |
9cfc7bd6 | 83 | */ |
8e7c15d6 SE |
84 | batadv_dbg(BATADV_DBG_BATMAN, bat_priv, |
85 | "Other host probably restarted!\n"); | |
c6c8fea2 | 86 | |
8e7c15d6 SE |
87 | bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); |
88 | if (set_mark) | |
89 | batadv_set_bit(seq_bits, 0); | |
c6c8fea2 | 90 | |
8e7c15d6 | 91 | return 1; |
c6c8fea2 | 92 | } |