1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /* Copyright (C) 2006-2020 B.A.T.M.A.N. contributors:
3*4882a593Smuzhiyun *
4*4882a593Smuzhiyun * Simon Wunderlich, Marek Lindner
5*4882a593Smuzhiyun */
6*4882a593Smuzhiyun
7*4882a593Smuzhiyun #include "bitarray.h"
8*4882a593Smuzhiyun #include "main.h"
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include <linux/bitmap.h>
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun #include "log.h"
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun /* shift the packet array by n places. */
batadv_bitmap_shift_left(unsigned long * seq_bits,s32 n)15*4882a593Smuzhiyun static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n)
16*4882a593Smuzhiyun {
17*4882a593Smuzhiyun if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE)
18*4882a593Smuzhiyun return;
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE);
21*4882a593Smuzhiyun }
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun /**
24*4882a593Smuzhiyun * batadv_bit_get_packet() - receive and process one packet within the sequence
25*4882a593Smuzhiyun * number window
26*4882a593Smuzhiyun * @priv: the bat priv with all the soft interface information
27*4882a593Smuzhiyun * @seq_bits: pointer to the sequence number receive packet
28*4882a593Smuzhiyun * @seq_num_diff: difference between the current/received sequence number and
29*4882a593Smuzhiyun * the last sequence number
30*4882a593Smuzhiyun * @set_mark: whether this packet should be marked in seq_bits
31*4882a593Smuzhiyun *
32*4882a593Smuzhiyun * Return: true if the window was moved (either new or very old),
33*4882a593Smuzhiyun * false if the window was not moved/shifted.
34*4882a593Smuzhiyun */
batadv_bit_get_packet(void * priv,unsigned long * seq_bits,s32 seq_num_diff,int set_mark)35*4882a593Smuzhiyun bool batadv_bit_get_packet(void *priv, unsigned long *seq_bits,
36*4882a593Smuzhiyun s32 seq_num_diff, int set_mark)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun struct batadv_priv *bat_priv = priv;
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun /* sequence number is slightly older. We already got a sequence number
41*4882a593Smuzhiyun * higher than this one, so we just mark it.
42*4882a593Smuzhiyun */
43*4882a593Smuzhiyun if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) {
44*4882a593Smuzhiyun if (set_mark)
45*4882a593Smuzhiyun batadv_set_bit(seq_bits, -seq_num_diff);
46*4882a593Smuzhiyun return false;
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun /* sequence number is slightly newer, so we shift the window and
50*4882a593Smuzhiyun * set the mark if required
51*4882a593Smuzhiyun */
52*4882a593Smuzhiyun if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) {
53*4882a593Smuzhiyun batadv_bitmap_shift_left(seq_bits, seq_num_diff);
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun if (set_mark)
56*4882a593Smuzhiyun batadv_set_bit(seq_bits, 0);
57*4882a593Smuzhiyun return true;
58*4882a593Smuzhiyun }
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun /* sequence number is much newer, probably missed a lot of packets */
61*4882a593Smuzhiyun if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE &&
62*4882a593Smuzhiyun seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) {
63*4882a593Smuzhiyun batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
64*4882a593Smuzhiyun "We missed a lot of packets (%i) !\n",
65*4882a593Smuzhiyun seq_num_diff - 1);
66*4882a593Smuzhiyun bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);
67*4882a593Smuzhiyun if (set_mark)
68*4882a593Smuzhiyun batadv_set_bit(seq_bits, 0);
69*4882a593Smuzhiyun return true;
70*4882a593Smuzhiyun }
71*4882a593Smuzhiyun
72*4882a593Smuzhiyun /* received a much older packet. The other host either restarted
73*4882a593Smuzhiyun * or the old packet got delayed somewhere in the network. The
74*4882a593Smuzhiyun * packet should be dropped without calling this function if the
75*4882a593Smuzhiyun * seqno window is protected.
76*4882a593Smuzhiyun *
77*4882a593Smuzhiyun * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE
78*4882a593Smuzhiyun * or
79*4882a593Smuzhiyun * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE
80*4882a593Smuzhiyun */
81*4882a593Smuzhiyun batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
82*4882a593Smuzhiyun "Other host probably restarted!\n");
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);
85*4882a593Smuzhiyun if (set_mark)
86*4882a593Smuzhiyun batadv_set_bit(seq_bits, 0);
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun return true;
89*4882a593Smuzhiyun }
90