1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Copyright (C) B.A.T.M.A.N. contributors: |
3 | * |
4 | * Simon Wunderlich, Marek Lindner |
5 | */ |
6 | |
7 | #include "bitarray.h" |
8 | #include "main.h" |
9 | |
10 | #include <linux/bitmap.h> |
11 | |
12 | #include "log.h" |
13 | |
14 | /* shift the packet array by n places. */ |
15 | static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n) |
16 | { |
17 | if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) |
18 | return; |
19 | |
20 | bitmap_shift_left(dst: seq_bits, src: seq_bits, shift: n, BATADV_TQ_LOCAL_WINDOW_SIZE); |
21 | } |
22 | |
23 | /** |
24 | * batadv_bit_get_packet() - receive and process one packet within the sequence |
25 | * number window |
26 | * @priv: the bat priv with all the soft interface information |
27 | * @seq_bits: pointer to the sequence number receive packet |
28 | * @seq_num_diff: difference between the current/received sequence number and |
29 | * the last sequence number |
30 | * @set_mark: whether this packet should be marked in seq_bits |
31 | * |
32 | * Return: true if the window was moved (either new or very old), |
33 | * false if the window was not moved/shifted. |
34 | */ |
35 | bool batadv_bit_get_packet(void *priv, unsigned long *seq_bits, |
36 | s32 seq_num_diff, int set_mark) |
37 | { |
38 | struct batadv_priv *bat_priv = priv; |
39 | |
40 | /* sequence number is slightly older. We already got a sequence number |
41 | * higher than this one, so we just mark it. |
42 | */ |
43 | if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) { |
44 | if (set_mark) |
45 | batadv_set_bit(seq_bits, n: -seq_num_diff); |
46 | return false; |
47 | } |
48 | |
49 | /* sequence number is slightly newer, so we shift the window and |
50 | * set the mark if required |
51 | */ |
52 | if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) { |
53 | batadv_bitmap_shift_left(seq_bits, n: seq_num_diff); |
54 | |
55 | if (set_mark) |
56 | batadv_set_bit(seq_bits, n: 0); |
57 | return true; |
58 | } |
59 | |
60 | /* sequence number is much newer, probably missed a lot of packets */ |
61 | if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && |
62 | seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { |
63 | batadv_dbg(BATADV_DBG_BATMAN, bat_priv, |
64 | "We missed a lot of packets (%i) !\n" , |
65 | seq_num_diff - 1); |
66 | bitmap_zero(dst: seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); |
67 | if (set_mark) |
68 | batadv_set_bit(seq_bits, n: 0); |
69 | return true; |
70 | } |
71 | |
72 | /* received a much older packet. The other host either restarted |
73 | * or the old packet got delayed somewhere in the network. The |
74 | * packet should be dropped without calling this function if the |
75 | * seqno window is protected. |
76 | * |
77 | * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE |
78 | * or |
79 | * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE |
80 | */ |
81 | batadv_dbg(BATADV_DBG_BATMAN, bat_priv, |
82 | "Other host probably restarted!\n" ); |
83 | |
84 | bitmap_zero(dst: seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); |
85 | if (set_mark) |
86 | batadv_set_bit(seq_bits, n: 0); |
87 | |
88 | return true; |
89 | } |
90 | |