From Colin O'Flynn:

The idea is that there is now some hardware that can put 802.15.4 frames over
Ethernet. To do so, the 802.15.4 frames are wrapped in an Ethernet frame, with
the Ethertype set to a value indicating the payload is 802.15.4.

Since there is no official ETHTYPE designated by the IEEE, the number 0x809A
is used in this code. However a preference is added to the "IEEE 802.15.4" type
in the preference dialog allowing you to change this ethtype to something else.

The hardware for those interested is the Atmel Raven USB Stick.

svn path=/trunk/; revision=26352

1 files changed, 33 insertions, 5 deletions

diff --git a/epan/dissectors/packet-ieee802154.c b/epan/dissectors/packet-ieee802154.c
index 5b604e1196..d92b0ec000 100644
--- a/epan/dissectors/packet-ieee802154.c
+++ b/epan/dissectors/packet-ieee802154.c
@@ -77,6 +77,7 @@
 #include <epan/crc16.h>
 #include <epan/expert.h>
 #include <epan/addr_resolv.h>
+#include <epan/prefs.h>
 
 #include "packet-ieee802154.h"
 #include "packet-frame.h"   /* For Exception Handling */
@@ -85,6 +86,9 @@
 #define DISSECT_IEEE802154_OPTION_CC24xx    0x00000001  /* FCS field contains a TI CC24xx style FCS. */
 #define DISSECT_IEEE802154_OPTION_LINUX     0x00000002  /* Addressing fields are padded DLT_IEEE802_15_4_LINUX, not implemented. */
 
+/* ethertype for 802.15.4 tag - encapsulating an Ethernet packet */
+static unsigned int ieee802154_ethertype = 0x809A;
+
 /*  Function declarations */
 /* Register Functions. Loads the dissector into Wireshark. */
 void proto_reg_handoff_ieee802154   (void);
@@ -1662,6 +1666,8 @@ void proto_register_ieee802154(void)
         &ett_ieee802154_bcn_pending
     };
 
+    module_t *ieee802154_module;
+
     /*  Register Protocol name and description. */
     proto_ieee802154 = proto_register_protocol("IEEE 802.15.4 Low-Rate Wireless PAN", "IEEE 802.15.4", "wpan");
 
@@ -1669,6 +1675,14 @@ void proto_register_ieee802154(void)
     proto_register_field_array(proto_ieee802154, hf, array_length(hf));
     proto_register_subtree_array(ett, array_length(ett));
 
+    /* add a user preference to set the 802.15.4 ethertype */
+    ieee802154_module = prefs_register_protocol(proto_ieee802154, 
+						proto_reg_handoff_ieee802154);
+    prefs_register_uint_preference(ieee802154_module, "802154_ethertype",
+				   "802.15.4 (Hex) Ethertype",
+				   "(Hexadecimal) Ethertype used to indicate IEEE 802.15.4 frame.",
+				   16, &ieee802154_ethertype);
+
     /* Register the subdissector list */
     register_heur_dissector_list("wpan", &ieee802154_heur_subdissector_list);
 
@@ -1684,6 +1698,7 @@ void proto_register_ieee802154(void)
  *  DESCRIPTION
  *      Registers the zigbee dissector with Wireshark.
  *      Will be called every time 'apply' is pressed in the preferences menu.
+ *       as well as during Wireshark initialization
  *  PARAMETERS
  *      none
  *  RETURNS
@@ -1692,13 +1707,26 @@ void proto_register_ieee802154(void)
  */
 void proto_reg_handoff_ieee802154(void)
 {
-    dissector_handle_t  ieee802154_handle;
+    static gboolean prefs_initialized = FALSE;
+    static dissector_handle_t  ieee802154_handle;
+    static unsigned int old_ieee802154_ethertype;
+
+    if (!prefs_initialized){
+        /* Get the dissector handles. */
+        ieee802154_handle   = find_dissector("wpan");
+        data_handle         = find_dissector("data");
 
-    /* Get the dissector handles. */
-    ieee802154_handle   = find_dissector("wpan");
-    data_handle         = find_dissector("data");
+        dissector_add("wtap_encap", WTAP_ENCAP_IEEE802_15_4, ieee802154_handle);
 
+        prefs_initialized = TRUE;
+    } else {
+        dissector_delete("ethertype", old_ieee802154_ethertype, ieee802154_handle);	
+    }
+
+    old_ieee802154_ethertype = ieee802154_ethertype;
+	
     /* Register dissector handles. */
-    dissector_add("wtap_encap", WTAP_ENCAP_IEEE802_15_4, ieee802154_handle);
+    dissector_add("ethertype", ieee802154_ethertype, ieee802154_handle);
+
 } /* proto_reg_handoff_ieee802154 */