1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2006-2018 B.A.T.M.A.N. contributors:
3 *
4 * Simon Wunderlich, Marek Lindner
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of version 2 of the GNU General Public
8 * License as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19 #include "bitarray.h"
20 #include "main.h"
21
22 #include <linux/bitmap.h>
23
24 #include "log.h"
25
26 /* shift the packet array by n places. */
batadv_bitmap_shift_left(unsigned long * seq_bits,s32 n)27 static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n)
28 {
29 if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE)
30 return;
31
32 bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE);
33 }
34
35 /**
36 * batadv_bit_get_packet() - receive and process one packet within the sequence
37 * number window
38 * @priv: the bat priv with all the soft interface information
39 * @seq_bits: pointer to the sequence number receive packet
40 * @seq_num_diff: difference between the current/received sequence number and
41 * the last sequence number
42 * @set_mark: whether this packet should be marked in seq_bits
43 *
44 * Return: true if the window was moved (either new or very old),
45 * false if the window was not moved/shifted.
46 */
batadv_bit_get_packet(void * priv,unsigned long * seq_bits,s32 seq_num_diff,int set_mark)47 bool batadv_bit_get_packet(void *priv, unsigned long *seq_bits,
48 s32 seq_num_diff, int set_mark)
49 {
50 struct batadv_priv *bat_priv = priv;
51
52 /* sequence number is slightly older. We already got a sequence number
53 * higher than this one, so we just mark it.
54 */
55 if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) {
56 if (set_mark)
57 batadv_set_bit(seq_bits, -seq_num_diff);
58 return false;
59 }
60
61 /* sequence number is slightly newer, so we shift the window and
62 * set the mark if required
63 */
64 if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) {
65 batadv_bitmap_shift_left(seq_bits, seq_num_diff);
66
67 if (set_mark)
68 batadv_set_bit(seq_bits, 0);
69 return true;
70 }
71
72 /* sequence number is much newer, probably missed a lot of packets */
73 if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE &&
74 seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) {
75 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
76 "We missed a lot of packets (%i) !\n",
77 seq_num_diff - 1);
78 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);
79 if (set_mark)
80 batadv_set_bit(seq_bits, 0);
81 return true;
82 }
83
84 /* received a much older packet. The other host either restarted
85 * or the old packet got delayed somewhere in the network. The
86 * packet should be dropped without calling this function if the
87 * seqno window is protected.
88 *
89 * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE
90 * or
91 * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE
92 */
93 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
94 "Other host probably restarted!\n");
95
96 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);
97 if (set_mark)
98 batadv_set_bit(seq_bits, 0);
99
100 return true;
101 }
102
