llsec: Disable duplicate detection when the LLSEC driver provides replay protection anyway.

core/net/mac/contikimac/contikimac.c

@@ -971,6 +971,7 @@ input_packet(void)
         ctimer_stop(&ct);
       }
 
+#if RDC_WITH_DUPLICATE_DETECTION
       /* Check for duplicate packet. */
       if(mac_sequence_is_duplicate()) {
         /* Drop the packet. */
@@ -978,6 +979,7 @@ input_packet(void)
         return;
       }
       mac_sequence_register_seqno();
+#endif /* RDC_WITH_DUPLICATE_DETECTION */
 
 #if CONTIKIMAC_CONF_COMPOWER
       /* Accumulate the power consumption for the packet reception. */

core/net/mac/nullrdc.c

@@ -298,6 +298,7 @@ packet_input(void)
     int duplicate = 0;
 
 #if NULLRDC_802154_AUTOACK || NULLRDC_802154_AUTOACK_HW
+#if RDC_WITH_DUPLICATE_DETECTION
     /* Check for duplicate packet. */
     duplicate = mac_sequence_is_duplicate();
     if(duplicate) {
@@ -307,8 +308,10 @@ packet_input(void)
     } else {
       mac_sequence_register_seqno();
     }
+#endif /* RDC_WITH_DUPLICATE_DETECTION */
 #endif /* NULLRDC_802154_AUTOACK */
 
+/* TODO We may want to acknowledge only authentic frames */ 
 #if NULLRDC_SEND_802154_ACK
     {
       frame802154_t info154;

core/net/mac/rdc.h

@@ -44,6 +44,16 @@
 #include "contiki-conf.h"
 #include "net/mac/mac.h"
 
+#ifdef RDC_CONF_WITH_DUPLICATE_DETECTION
+#define RDC_WITH_DUPLICATE_DETECTION RDC_CONF_WITH_DUPLICATE_DETECTION
+#else /* RDC_CONF_WITH_DUPLICATE_DETECTION */
+/* As frames can be spoofed, the RDC layer should not discard a
+   frame because it has seen its sequence number already. Replay
+   protection should be implemented at the LLSEC layer where the
+   authenticity of frames is verified. */
+#define RDC_WITH_DUPLICATE_DETECTION !LLSEC802154_CONF_SECURITY_LEVEL
+#endif /* RDC_CONF_WITH_DUPLICATE_DETECTION */
+
 /* List of packets to be sent by RDC layer */
 struct rdc_buf_list {
   struct rdc_buf_list *next;