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(seq_bits, seq_bits, 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, -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, seq_num_diff); 54 55 if (set_mark) 56 batadv_set_bit(seq_bits, 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(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 67 if (set_mark) 68 batadv_set_bit(seq_bits, 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(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 85 if (set_mark) 86 batadv_set_bit(seq_bits, 0); 87 88 return true; 89 } 90