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 */
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
update_routes(orig_node, orig_node->router, hna_buff, tmp_hna_buff_len);
}
+/* checks whether the host restarted and is in the protection time.
+ * returns:
+ * 0 if the packet is to be accepted
+ * 1 if the packet is to be ignored.
+ */
+static int window_protected(int16_t seq_num_diff,
+ unsigned long *last_reset)
+{
+ if ((seq_num_diff <= -TQ_LOCAL_WINDOW_SIZE)
+ || (seq_num_diff >= EXPECTED_SEQNO_RANGE)) {
+ if (time_after(jiffies, *last_reset +
+ msecs_to_jiffies(RESET_PROTECTION_MS))) {
+
+ *last_reset = jiffies;
+ bat_dbg(DBG_BATMAN,
+ "old packet received, start protection\n");
+
+ return 0;
+ } else
+ return 1;
+ }
+ return 0;
+}
+
+/* processes a batman packet for all interfaces, adjusts the sequence number and
+ * finds out whether it is a duplicate.
+ * returns:
+ * 1 the packet is a duplicate
+ * 0 the packet has not yet been received
+ * -1 the packet is old and has been received while the seqno window
+ * was protected. Caller should drop it.
+ */
static char count_real_packets(struct ethhdr *ethhdr,
struct batman_packet *batman_packet,
struct batman_if *if_incoming)
struct orig_node *orig_node;
struct neigh_node *tmp_neigh_node;
char is_duplicate = 0;
- uint16_t seq_diff;
+ int16_t seq_diff;
+ int need_update = 0;
+ int set_mark;
orig_node = get_orig_node(batman_packet->orig);
if (orig_node == NULL)
return 0;
+ seq_diff = batman_packet->seqno - orig_node->last_real_seqno;
+
+ /* signalize caller that the packet is to be dropped. */
+ if (window_protected(seq_diff, &orig_node->batman_seqno_reset))
+ return -1;
+
list_for_each_entry(tmp_neigh_node, &orig_node->neigh_list, list) {
- if (!is_duplicate)
- is_duplicate =
- get_bit_status(tmp_neigh_node->real_bits,
+ is_duplicate |= get_bit_status(tmp_neigh_node->real_bits,
orig_node->last_real_seqno,
batman_packet->seqno);
- seq_diff = batman_packet->seqno - orig_node->last_real_seqno;
+
if (compare_orig(tmp_neigh_node->addr, ethhdr->h_source) &&
(tmp_neigh_node->if_incoming == if_incoming))
- bit_get_packet(tmp_neigh_node->real_bits, seq_diff, 1);
+ set_mark = 1;
else
- bit_get_packet(tmp_neigh_node->real_bits, seq_diff, 0);
+ set_mark = 0;
+
+ /* if the window moved, set the update flag. */
+ need_update |= bit_get_packet(tmp_neigh_node->real_bits,
+ seq_diff, set_mark);
tmp_neigh_node->real_packet_count =
bit_packet_count(tmp_neigh_node->real_bits);
}
- if (!is_duplicate) {
+ if (need_update) {
bat_dbg(DBG_BATMAN, "updating last_seqno: old %d, new %d\n",
orig_node->last_real_seqno, batman_packet->seqno);
orig_node->last_real_seqno = batman_packet->seqno;
return;
}
- if (batman_packet->tq == 0) {
- count_real_packets(ethhdr, batman_packet, if_incoming);
-
- bat_dbg(DBG_BATMAN, "Drop packet: originator packet with tq equal 0\n");
- return;
- }
-
if (is_my_oldorig) {
bat_dbg(DBG_BATMAN, "Drop packet: ignoring all rebroadcast echos (sender: %pM)\n", ethhdr->h_source);
return;
}
- is_duplicate = count_real_packets(ethhdr, batman_packet, if_incoming);
-
orig_node = get_orig_node(batman_packet->orig);
if (orig_node == NULL)
return;
+ is_duplicate = count_real_packets(ethhdr, batman_packet, if_incoming);
+
+ if (is_duplicate == -1) {
+ bat_dbg(DBG_BATMAN, "Drop packet: packet within seqno protection time (sender: %pM)\n", ethhdr->h_source);
+ return;
+ }
+
+ if (batman_packet->tq == 0) {
+ bat_dbg(DBG_BATMAN, "Drop packet: originator packet with tq equal 0\n");
+ return;
+ }
+
/* avoid temporary routing loops */
if ((orig_node->router) &&
(orig_node->router->orig_node->router) &&
return ret;
}
-
int recv_bcast_packet(struct sk_buff *skb)
{
struct orig_node *orig_node;
struct bcast_packet *bcast_packet;
struct ethhdr *ethhdr;
int hdr_size = sizeof(struct bcast_packet);
+ int16_t seq_diff;
unsigned long flags;
/* drop packet if it has not necessary minimum size */
return NET_RX_DROP;
}
- /* check flood history */
+ /* check whether the packet is a duplicate */
if (get_bit_status(orig_node->bcast_bits,
orig_node->last_bcast_seqno,
ntohs(bcast_packet->seqno))) {
return NET_RX_DROP;
}
- /* mark broadcast in flood history */
- if (bit_get_packet(orig_node->bcast_bits,
- ntohs(bcast_packet->seqno) -
- orig_node->last_bcast_seqno, 1))
+ seq_diff = ntohs(bcast_packet->seqno) - orig_node->last_bcast_seqno;
+
+ /* check whether the packet is old and the host just restarted. */
+ if (window_protected(seq_diff, &orig_node->bcast_seqno_reset)) {
+ spin_unlock_irqrestore(&orig_hash_lock, flags);
+ return NET_RX_DROP;
+ }
+
+ /* mark broadcast in flood history, update window position
+ * if required. */
+ if (bit_get_packet(orig_node->bcast_bits, seq_diff, 1))
orig_node->last_bcast_seqno = ntohs(bcast_packet->seqno);
spin_unlock_irqrestore(&orig_hash_lock, flags);
-
/* rebroadcast packet */
add_bcast_packet_to_list(skb);
projects / openwrt / staging / blogic.git / commitdiff