1 /* Copyright (C) 2006-2016 B.A.T.M.A.N. contributors: 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 15 * along with this program; if not, see <http://www.gnu.org/licenses/>. 16 */ 17 18 #include "bitarray.h" 19 #include "main.h" 20 21 #include <linux/bitmap.h> 22 23 /* shift the packet array by n places. */ 24 static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n) 25 { 26 if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) 27 return; 28 29 bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE); 30 } 31 32 /** 33 * batadv_bit_get_packet - receive and process one packet within the sequence 34 * number window 35 * @priv: the bat priv with all the soft interface information 36 * @seq_bits: pointer to the sequence number receive packet 37 * @seq_num_diff: difference between the current/received sequence number and 38 * the last sequence number 39 * @set_mark: whether this packet should be marked in seq_bits 40 * 41 * Return: 1 if the window was moved (either new or very old), 42 * 0 if the window was not moved/shifted. 43 */ 44 int batadv_bit_get_packet(void *priv, unsigned long *seq_bits, s32 seq_num_diff, 45 int set_mark) 46 { 47 struct batadv_priv *bat_priv = priv; 48 49 /* sequence number is slightly older. We already got a sequence number 50 * higher than this one, so we just mark it. 51 */ 52 if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) { 53 if (set_mark) 54 batadv_set_bit(seq_bits, -seq_num_diff); 55 return 0; 56 } 57 58 /* sequence number is slightly newer, so we shift the window and 59 * set the mark if required 60 */ 61 if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) { 62 batadv_bitmap_shift_left(seq_bits, seq_num_diff); 63 64 if (set_mark) 65 batadv_set_bit(seq_bits, 0); 66 return 1; 67 } 68 69 /* sequence number is much newer, probably missed a lot of packets */ 70 if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && 71 seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { 72 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 73 "We missed a lot of packets (%i) !\n", 74 seq_num_diff - 1); 75 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 76 if (set_mark) 77 batadv_set_bit(seq_bits, 0); 78 return 1; 79 } 80 81 /* received a much older packet. The other host either restarted 82 * or the old packet got delayed somewhere in the network. The 83 * packet should be dropped without calling this function if the 84 * seqno window is protected. 85 * 86 * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE 87 * or 88 * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE 89 */ 90 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 91 "Other host probably restarted!\n"); 92 93 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 94 if (set_mark) 95 batadv_set_bit(seq_bits, 0); 96 97 return 1; 98 } 99