// SPDX-License-Identifier: GPL-2.0 /* Copyright (C) 2006-2019 B.A.T.M.A.N. contributors: * * Simon Wunderlich, Marek Lindner */ #include "bitarray.h" #include "main.h" #include <linux/bitmap.h> #include "log.h" /* shift the packet array by n places. */ static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n) { if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) return; bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE); } /** * batadv_bit_get_packet() - receive and process one packet within the sequence * number window * @priv: the bat priv with all the soft interface information * @seq_bits: pointer to the sequence number receive packet * @seq_num_diff: difference between the current/received sequence number and * the last sequence number * @set_mark: whether this packet should be marked in seq_bits * * Return: true if the window was moved (either new or very old), * false if the window was not moved/shifted. */ bool batadv_bit_get_packet(void *priv, unsigned long *seq_bits, s32 seq_num_diff, int set_mark) { struct batadv_priv *bat_priv = priv; /* sequence number is slightly older. We already got a sequence number * higher than this one, so we just mark it. */ if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) { if (set_mark) batadv_set_bit(seq_bits, -seq_num_diff); return false; } /* sequence number is slightly newer, so we shift the window and * set the mark if required */ if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) { batadv_bitmap_shift_left(seq_bits, seq_num_diff); if (set_mark) batadv_set_bit(seq_bits, 0); return true; } /* sequence number is much newer, probably missed a lot of packets */ if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "We missed a lot of packets (%i) !\n", seq_num_diff - 1); bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); if (set_mark) batadv_set_bit(seq_bits, 0); return true; } /* received a much older packet. The other host either restarted * or the old packet got delayed somewhere in the network. The * packet should be dropped without calling this function if the * seqno window is protected. * * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE * or * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE */ batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Other host probably restarted!\n"); bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); if (set_mark) batadv_set_bit(seq_bits, 0); return true; }