diff options
Diffstat (limited to 'drivers/staging/batman-adv/bitarray.c')
| -rw-r--r-- | drivers/staging/batman-adv/bitarray.c | 76 |
1 files changed, 52 insertions, 24 deletions
diff --git a/drivers/staging/batman-adv/bitarray.c b/drivers/staging/batman-adv/bitarray.c index 212eef93afe4..2fef6e35f8c3 100644 --- a/drivers/staging/batman-adv/bitarray.c +++ b/drivers/staging/batman-adv/bitarray.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2006-2009 B.A.T.M.A.N. contributors: + * Copyright (C) 2006-2010 B.A.T.M.A.N. contributors: * * Simon Wunderlich, Marek Lindner * @@ -68,7 +68,7 @@ void bit_shift(TYPE_OF_WORD *seq_bits, int32_t n) int32_t word_offset, word_num; int32_t i; - if (n <= 0) + if (n <= 0 || n >= TQ_LOCAL_WINDOW_SIZE) return; word_offset = n % WORD_BIT_SIZE;/* shift how much inside each word */ @@ -111,48 +111,76 @@ void bit_shift(TYPE_OF_WORD *seq_bits, int32_t n) seq_bits[i] = 0; } +static void bit_reset_window(TYPE_OF_WORD *seq_bits) +{ + int i; + for (i = 0; i < NUM_WORDS; i++) + seq_bits[i] = 0; +} + -/* receive and process one packet, returns 1 if received seq_num is considered - * new, 0 if old */ +/* 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. + */ char bit_get_packet(TYPE_OF_WORD *seq_bits, int16_t seq_num_diff, int8_t set_mark) { - int i; + /* sequence number is slightly older. We already got a sequence number + * higher than this one, so we just mark it. */ - /* we already got a sequence number higher than this one, so we just - * mark it. this should wrap around the integer just fine */ - if ((seq_num_diff < 0) && (seq_num_diff >= -TQ_LOCAL_WINDOW_SIZE)) { + if ((seq_num_diff <= 0) && (seq_num_diff > -TQ_LOCAL_WINDOW_SIZE)) { if (set_mark) bit_mark(seq_bits, -seq_num_diff); return 0; } - /* it seems we missed a lot of packets or the other host restarted */ - if ((seq_num_diff > TQ_LOCAL_WINDOW_SIZE) || - (seq_num_diff < -TQ_LOCAL_WINDOW_SIZE)) { + /* sequence number is slightly newer, so we shift the window and + * set the mark if required */ - if (seq_num_diff > TQ_LOCAL_WINDOW_SIZE) - bat_dbg(DBG_BATMAN, - "We missed a lot of packets (%i) !\n", - seq_num_diff-1); + if ((seq_num_diff > 0) && (seq_num_diff < TQ_LOCAL_WINDOW_SIZE)) { + bit_shift(seq_bits, seq_num_diff); - if (-seq_num_diff > TQ_LOCAL_WINDOW_SIZE) - bat_dbg(DBG_BATMAN, - "Other host probably restarted !\n"); + if (set_mark) + bit_mark(seq_bits, 0); + return 1; + } - for (i = 0; i < NUM_WORDS; i++) - seq_bits[i] = 0; + /* sequence number is much newer, probably missed a lot of packets */ + if ((seq_num_diff >= TQ_LOCAL_WINDOW_SIZE) + || (seq_num_diff < EXPECTED_SEQNO_RANGE)) { + bat_dbg(DBG_BATMAN, + "We missed a lot of packets (%i) !\n", + seq_num_diff - 1); + bit_reset_window(seq_bits); if (set_mark) - seq_bits[0] = 1; /* we only have the latest packet */ - } else { - bit_shift(seq_bits, seq_num_diff); + bit_mark(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. */ + + if ((seq_num_diff <= -TQ_LOCAL_WINDOW_SIZE) + || (seq_num_diff >= EXPECTED_SEQNO_RANGE)) { + bat_dbg(DBG_BATMAN, + "Other host probably restarted!\n"); + + bit_reset_window(seq_bits); if (set_mark) bit_mark(seq_bits, 0); + + return 1; } - return 1; + /* never reached */ + return 0; } /* count the hamming weight, how many good packets did we receive? just count |