1 /* Copyright (C) 2006-2015 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 /* receive and process one packet within the sequence number window. 33 * 34 * returns: 35 * 1 if the window was moved (either new or very old) 36 * 0 if the window was not moved/shifted. 37 */ 38 int batadv_bit_get_packet(void *priv, unsigned long *seq_bits, s32 seq_num_diff, 39 int set_mark) 40 { 41 struct batadv_priv *bat_priv = priv; 42 43 /* sequence number is slightly older. We already got a sequence number 44 * higher than this one, so we just mark it. 45 */ 46 if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) { 47 if (set_mark) 48 batadv_set_bit(seq_bits, -seq_num_diff); 49 return 0; 50 } 51 52 /* sequence number is slightly newer, so we shift the window and 53 * set the mark if required 54 */ 55 if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) { 56 batadv_bitmap_shift_left(seq_bits, seq_num_diff); 57 58 if (set_mark) 59 batadv_set_bit(seq_bits, 0); 60 return 1; 61 } 62 63 /* sequence number is much newer, probably missed a lot of packets */ 64 if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && 65 seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { 66 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 67 "We missed a lot of packets (%i) !\n", 68 seq_num_diff - 1); 69 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 70 if (set_mark) 71 batadv_set_bit(seq_bits, 0); 72 return 1; 73 } 74 75 /* received a much older packet. The other host either restarted 76 * or the old packet got delayed somewhere in the network. The 77 * packet should be dropped without calling this function if the 78 * seqno window is protected. 79 * 80 * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE 81 * or 82 * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE 83 */ 84 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 85 "Other host probably restarted!\n"); 86 87 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 88 if (set_mark) 89 batadv_set_bit(seq_bits, 0); 90 91 return 1; 92 } 93