From 91ff8574ad48be321ea6e7f73418708d47138b08 Mon Sep 17 00:00:00 2001
From: adamdunkels <adamdunkels>
Date: Thu, 8 Apr 2010 09:32:56 +0000
Subject: [PATCH] Improved handling of duplicate packets

---
 core/net/mac/contikimac.c    | 41 ++++++++++++++++++++++++------------
 core/net/mac/csma.c          |  9 +++++---
 core/net/mac/framer-802154.c |  9 ++++++--
 3 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/core/net/mac/contikimac.c b/core/net/mac/contikimac.c
index 1718edc1e..779731b54 100644
--- a/core/net/mac/contikimac.c
+++ b/core/net/mac/contikimac.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: contikimac.c,v 1.30 2010/04/06 11:57:43 adamdunkels Exp $
+ * $Id: contikimac.c,v 1.31 2010/04/08 09:32:56 adamdunkels Exp $
  */
 
 /**
@@ -192,8 +192,13 @@ static volatile rtimer_clock_t stream_until;
 #define MIN(a, b) ((a) < (b)? (a) : (b))
 #endif /* MIN */
 
-static int last_received_seqno;
-static rimeaddr_t last_received_sender;
+struct seqno {
+  rimeaddr_t sender;
+  uint8_t seqno;
+};
+
+#define MAX_SEQNOS 8
+static struct seqno received_seqnos[MAX_SEQNOS];
 
 #if CONTIKIMAC_CONF_BROADCAST_RATE_LIMIT
 static struct timer broadcast_rate_timer;
@@ -896,19 +901,27 @@ input_packet(void)
 #endif /* WITH_PHASE_OPTIMIZATION */
 
       /* Check for duplicate packet by comparing the sequence number
-         of the incoming packet with the last one we saw. */
-      if(packetbuf_attr(PACKETBUF_ATTR_PACKET_ID) == last_received_seqno &&
-         rimeaddr_cmp(packetbuf_addr(PACKETBUF_ADDR_SENDER),
-                      &last_received_sender)) {
-        /* Drop the packet. */
-        /*        printf("Drop duplicate ContikiMAC layer packet\n");*/
-        return;
+         of the incoming packet with the last few ones we saw. */
+      {
+        int i;
+        for(i = 0; i < MAX_SEQNOS; ++i) {
+          if(packetbuf_attr(PACKETBUF_ATTR_PACKET_ID) == received_seqnos[i].seqno &&
+             rimeaddr_cmp(packetbuf_addr(PACKETBUF_ADDR_SENDER),
+                          &received_seqnos[i].sender)) {
+            /* Drop the packet. */
+            /*        printf("Drop duplicate ContikiMAC layer packet\n");*/
+            return;
+          }
+        }
+        for(i = MAX_SEQNOS - 1; i > 0; --i) {
+          memcpy(&received_seqnos[i], &received_seqnos[i - 1],
+                 sizeof(struct seqno));
+        }
+        received_seqnos[0].seqno = packetbuf_attr(PACKETBUF_ATTR_PACKET_ID);
+        rimeaddr_copy(&received_seqnos[0].sender,
+                      packetbuf_addr(PACKETBUF_ADDR_SENDER));
       }
 
-
-      last_received_seqno = packetbuf_attr(PACKETBUF_ATTR_PACKET_ID);
-      rimeaddr_copy(&last_received_sender, packetbuf_addr(PACKETBUF_ADDR_SENDER));
-
 #if CONTIKIMAC_CONF_COMPOWER
       /* Accumulate the power consumption for the packet reception. */
       compower_accumulate(&current_packet);
diff --git a/core/net/mac/csma.c b/core/net/mac/csma.c
index 62d4e3714..76e059146 100644
--- a/core/net/mac/csma.c
+++ b/core/net/mac/csma.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: csma.c,v 1.15 2010/03/26 12:29:29 nifi Exp $
+ * $Id: csma.c,v 1.16 2010/04/08 09:33:37 adamdunkels Exp $
  */
 
 /**
@@ -164,7 +164,7 @@ packet_sent(void *ptr, int status, int num_transmissions)
     /* The retransmission time uses a linear backoff so that the
        interval between the transmissions increase with each
        retransmit. */
-    time = time + (random_rand() % ((q->collisions + q->transmissions) * 3 * time));
+    time = time + (random_rand() % ((q->transmissions + 1) * 3 * time));
     
     if(q->transmissions < q->max_transmissions) {
       PRINTF("csma: retransmitting with time %lu\n", time);
@@ -186,7 +186,10 @@ static void
 send_packet(mac_callback_t sent, void *ptr)
 {
   struct queued_packet *q;
-
+  static uint16_t seqno;
+  
+  packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, seqno++);
+  
   /* Remember packet for later. */
   q = memb_alloc(&packet_memb);
   if(q != NULL) {
diff --git a/core/net/mac/framer-802154.c b/core/net/mac/framer-802154.c
index 72dbc347a..686f2e2e4 100644
--- a/core/net/mac/framer-802154.c
+++ b/core/net/mac/framer-802154.c
@@ -26,7 +26,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: framer-802154.c,v 1.9 2010/04/05 19:28:07 adamdunkels Exp $
+ * $Id: framer-802154.c,v 1.10 2010/04/08 09:32:56 adamdunkels Exp $
  */
 
 /**
@@ -101,7 +101,12 @@ create(void)
   params.fcf.frame_version = FRAME802154_IEEE802154_2003;
 
   /* Increment and set the data sequence number. */
-  params.seq = mac_dsn++;
+  if(packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO)) {
+    params.seq = packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO);
+  } else {
+    params.seq = mac_dsn++;
+    packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, params.seq);
+  }
 /*   params.seq = packetbuf_attr(PACKETBUF_ATTR_PACKET_ID); */
 
   /* Complete the addressing fields. */