[B.A.T.M.A.N.] [RFC 3/3] batman-adv: seqnumber is wrap around safe
From: Edo Monticelli <hidden>
Date: 2012-08-09 12:15:26
Subsystem:
the rest · Maintainer:
Linus Torvalds
Sequence number in packet header is 16 bit and is made wrap around safe. Two 32 bit counters, window_first and total_to_send are locally kept in the struct bw_vars. On packet or acks arrival batadv_seq_before()/after() are used to check seqno against 16bit version of these counters. BATADV_BW_FIRST_SEQ is the sequence number of the first packet. It is set to 65530 to generate a wrap-around. *Both sides must agree on this value* Signed-off-by: Edo Monticelli <redacted> --- bw_meter.c | 56 +++++++++++++++++++++++++++++++------------------------- types.h | 4 ++-- 2 files changed, 33 insertions(+), 27 deletions(-)
diff --git a/bw_meter.c b/bw_meter.c
index b582ab0..c636c53 100644
--- a/bw_meter.c
+++ b/bw_meter.c@@ -16,6 +16,7 @@ #define BATADV_BW_RECV_TIMEOUT 1000 #define BATADV_BW_TOTAL_TO_SEND 5000 #define BATADV_BW_MAX_RETRY 3 +#define BATADV_BW_FIRST_SEQ 65530 static int batadv_bw_queue_sender_worker(struct batadv_bw_vars *bw_vars); static int batadv_bw_queue_receiver_worker(struct batadv_bw_vars *bw_vars);
@@ -158,7 +159,7 @@ void batadv_bw_meter_received(struct batadv_priv *bat_priv, struct sk_buff *skb) struct batadv_bw_vars *bw_vars; struct batadv_icmp_packet *icmp_packet; struct batadv_socket_client *socket_client; - uint16_t seqno; + uint16_t seqno, window_first_16; socket_client = container_of(&bat_priv, struct batadv_socket_client, bat_priv);
@@ -169,7 +170,7 @@ void batadv_bw_meter_received(struct batadv_priv *bat_priv, struct sk_buff *skb) seqno = ntohs(icmp_packet->seqno); bw_vars = batadv_bw_list_find(bat_priv, &icmp_packet->dst); if (!bw_vars) { - if (seqno != 0) { + if (seqno != BATADV_BW_FIRST_SEQ) { spin_unlock_bh(&bat_priv->bw_list_lock); batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Meter: seq != 0 cannot initiate connection\n");
@@ -184,7 +185,7 @@ void batadv_bw_meter_received(struct batadv_priv *bat_priv, struct sk_buff *skb) } memcpy(&bw_vars->other_end, &icmp_packet->dst, ETH_ALEN); bw_vars->status = RECEIVER; - bw_vars->window_first = 0; + bw_vars->window_first = BATADV_BW_FIRST_SEQ; bw_vars->bat_priv = bat_priv; spin_lock_init(&bw_vars->bw_vars_lock); list_add(&bw_vars->list, &bat_priv->bw_list);
@@ -199,18 +200,20 @@ void batadv_bw_meter_received(struct batadv_priv *bat_priv, struct sk_buff *skb) "Meter: dropping packet: connection is not expecting any\n"); goto out; } + window_first_16 = (uint16_t) bw_vars->window_first; spin_unlock_bh(&bat_priv->bw_list_lock); /* check if the packet belongs to window */ spin_lock_bh(&bw_vars->bw_vars_lock); - if (seqno < bw_vars->window_first) { + if (batadv_seq_before(seqno, window_first_16)) { spin_unlock_bh(&bw_vars->bw_vars_lock); batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Meter: %d < window_first\n", icmp_packet->seqno); goto out; /* TODO send an ack! */ } - if (seqno > bw_vars->window_first + BATADV_BW_WINDOW_SIZE) { + if (batadv_seq_after(seqno, (uint16_t) (window_first_16 + + BATADV_BW_WINDOW_SIZE))) { spin_unlock_bh(&bw_vars->bw_vars_lock); batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Meter: unexpected packet received\n");
@@ -218,7 +221,7 @@ void batadv_bw_meter_received(struct batadv_priv *bat_priv, struct sk_buff *skb) } /* packet does belong to the window */ - if (seqno == bw_vars->window_first) { + if (seqno == window_first_16) { bw_vars->window_first++; bw_vars->last_sent_time = jiffies; spin_unlock_bh(&bw_vars->bw_vars_lock);
@@ -253,7 +256,7 @@ static int batadv_bw_multiple_send(struct batadv_priv *bat_priv, struct batadv_icmp_packet *icmp_to_send; struct batadv_socket_client *socket_client; int ret, bw_packet_len; - uint16_t window_default_end, window_end, next_to_send; + uint16_t window_end, next_to_send; ret = -1; bw_packet_len = BATADV_BW_PACKET_LEN;
@@ -265,9 +268,8 @@ static int batadv_bw_multiple_send(struct batadv_priv *bat_priv, while (1) { spin_lock_bh(&bw_vars->bw_window_first_lock); - window_default_end = bw_vars->window_first + - BATADV_BW_WINDOW_SIZE; - window_end = min(window_default_end, bw_vars->total_to_send); + window_end = min(bw_vars->window_first + BATADV_BW_WINDOW_SIZE, + bw_vars->total_to_send); if (!batadv_seq_before(bw_vars->next_to_send, window_end)) { spin_unlock_bh(&bw_vars->bw_send_lock);
@@ -275,12 +277,15 @@ static int batadv_bw_multiple_send(struct batadv_priv *bat_priv, break; } - next_to_send = bw_vars->next_to_send++; bw_vars->last_sent_time = jiffies; + next_to_send = bw_vars->next_to_send++; spin_unlock_bh(&bw_vars->bw_window_first_lock); - if (bw_vars->next_to_send == bw_vars->total_to_send) + if ((bw_vars->window_first + BATADV_BW_WINDOW_SIZE >= + bw_vars->total_to_send) && + bw_vars->next_to_send == (uint16_t)bw_vars->total_to_send) { bw_packet_len -= 1; + } skb = dev_alloc_skb(bw_packet_len + ETH_HLEN); if (!skb) {
@@ -320,7 +325,7 @@ void batadv_bw_ack_received(struct batadv_priv *bat_priv, { struct batadv_icmp_packet *icmp_packet; struct batadv_bw_vars *bw_vars; - uint16_t window_end, seqno; + uint16_t seqno, window_end, window_first_16; icmp_packet = (struct batadv_icmp_packet *)skb->data;
@@ -338,10 +343,11 @@ void batadv_bw_ack_received(struct batadv_priv *bat_priv, /* slide and send fresh packets */ spin_lock_bh(&bw_vars->bw_window_first_lock); seqno = ntohs(icmp_packet->seqno); - window_end = bw_vars->window_first + BATADV_BW_WINDOW_SIZE; - if (!batadv_seq_after(bw_vars->window_first, seqno) && + window_first_16 = (uint16_t) bw_vars->window_first; + window_end = window_first_16 + BATADV_BW_WINDOW_SIZE; + if (!batadv_seq_after(window_first_16, seqno) && batadv_seq_before(seqno, bw_vars->next_to_send)) { - bw_vars->window_first = seqno + 1; + bw_vars->window_first += seqno + 1 - window_first_16; } else if (bw_vars->status != ABORTING) { batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "Meter: received unespected ack\n");
@@ -393,14 +399,15 @@ static void batadv_bw_sender_worker(struct work_struct *work) if (bw_vars->window_first == bw_vars->last_resent_window) { bw_vars->retry_number += 1; if (bw_vars->retry_number > BATADV_BW_MAX_RETRY) { - bw_vars->window_first = BATADV_BW_TOTAL_TO_SEND; + bw_vars->window_first = bw_vars->total_to_send; bw_vars->status = ABORTING; } } else { bw_vars->retry_number = 0; } - pr_info("RESENDING WHOLE WINDOW %d\n", bw_vars->window_first); + pr_info("RESENDING WHOLE WINDOW %d\n", + (uint16_t)bw_vars->window_first); bw_vars->last_resent_window = bw_vars->window_first; bw_vars->next_to_send = bw_vars->window_first; batadv_bw_multiple_send(bat_priv, bw_vars);
@@ -422,9 +429,8 @@ static void batadv_bw_sender_worker(struct work_struct *work) result->total_bytes = 0; } else { result->test_time = ((long)jiffies - - (long)bw_vars->start_time) * - (1000/HZ); - result->total_bytes = bw_vars->total_to_send * + (long)bw_vars->start_time); + result->total_bytes = BATADV_BW_TOTAL_TO_SEND * BATADV_BW_PACKET_LEN; } batadv_socket_receive_packet(icmp_packet_rr,
@@ -468,7 +474,7 @@ void batadv_bw_stop(struct batadv_priv *bat_priv, } spin_unlock_bh(&bat_priv->bw_list_lock); spin_lock_bh(&bw_vars->bw_window_first_lock); - bw_vars->window_first = BATADV_BW_TOTAL_TO_SEND; + bw_vars->window_first = bw_vars->total_to_send; bw_vars->status = ABORTING; spin_unlock_bh(&bw_vars->bw_window_first_lock); }
@@ -500,9 +506,9 @@ void batadv_bw_start(struct batadv_socket_client *socket_client, /* initialize bw_vars */ memcpy(&bw_vars->other_end, &icmp_packet->dst, ETH_ALEN); - bw_vars->total_to_send = BATADV_BW_TOTAL_TO_SEND; - bw_vars->next_to_send = 0; - bw_vars->window_first = 0; + bw_vars->total_to_send = BATADV_BW_TOTAL_TO_SEND + BATADV_BW_FIRST_SEQ; + bw_vars->window_first = BATADV_BW_FIRST_SEQ; + bw_vars->next_to_send = BATADV_BW_FIRST_SEQ; bw_vars->last_resent_window = 0; bw_vars->bat_priv = bat_priv; bw_vars->socket_client = socket_client;
diff --git a/types.h b/types.h
index e5ba150..dd515e6 100644
--- a/types.h
+++ b/types.h@@ -245,10 +245,10 @@ struct batadv_bw_vars { /* protects multiple_send calls */ spinlock_t bw_send_lock; /* total data to send OR window data received */ - uint16_t total_to_send; + uint32_t total_to_send; /* offset of the first window packet */ uint16_t next_to_send; - uint16_t window_first; + uint32_t window_first; uint8_t other_end[ETH_ALEN]; uint8_t status; /* see bm_meter_status */ unsigned long start_time;
--
1.7.8.6