/* Copyright (C) 2006-2014 B.A.T.M.A.N. contributors: | |

* | |

* Simon Wunderlich, Marek Lindner | |

* | |

* This program is free software; you can redistribute it and/or | |

* modify it under the terms of version 2 of the GNU General Public | |

* License as published by the Free Software Foundation. | |

* | |

* This program is distributed in the hope that it will be useful, but | |

* WITHOUT ANY WARRANTY; without even the implied warranty of | |

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |

* General Public License for more details. | |

* | |

* You should have received a copy of the GNU General Public License | |

* along with this program; if not, see <http://www.gnu.org/licenses/>. | |

*/ | |

#include "main.h" | |

#include "bitarray.h" | |

#include <linux/bitops.h> | |

/* shift the packet array by n places. */ | |

static void batadv_bitmap_shift_left(unsigned long *seq_bits, int32_t n) | |

{ | |

if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) | |

return; | |

bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE); | |

} | |

/* receive and process one packet within the sequence number window. | |

* | |

* returns: | |

* 1 if the window was moved (either new or very old) | |

* 0 if the window was not moved/shifted. | |

*/ | |

int batadv_bit_get_packet(void *priv, unsigned long *seq_bits, | |

int32_t 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 0; | |

} | |

/* 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 1; | |

} | |

/* 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 1; | |

} | |

/* 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 1; | |

} |