nordic_ble: Fix calculating delta time start to start

The calculation must be based on the length of the previous packet,
not the last packet selected in the list.

Also mark this entry as generated.

Change-Id: I2e0a30ce28f5824f73ffe2d90d3043ff309292dc
Reviewed-on: https://code.wireshark.org/review/23191
Petri-Dish: Stig Bjørlykke <stig@bjorlykke.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Stig Bjørlykke <stig@bjorlykke.org>

1 files changed, 23 insertions, 9 deletions

diff --git a/epan/dissectors/packet-nordic_ble.c b/epan/dissectors/packet-nordic_ble.c
index bdf5037d8e..497da3877a 100644
--- a/epan/dissectors/packet-nordic_ble.c
+++ b/epan/dissectors/packet-nordic_ble.c
@@ -117,6 +117,9 @@
 
 #include <epan/packet.h>
 #include <epan/expert.h>
+#include <epan/proto_data.h>
+
+#include <wsutil/utf8_entities.h>
 
 #include "packet-btle.h"
 
@@ -268,10 +271,18 @@ dissect_flags(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree,
 }
 
 static gint
-dissect_ble_delta_time(tvbuff_t *tvb, gint offset, proto_tree *tree, guint8 packet_len)
+dissect_ble_delta_time(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree, guint8 packet_len)
 {
     static guint8 previous_ble_packet_length = 0;
     guint32 delta_time, delta_time_ss;
+    proto_item *pi;
+
+    if (!pinfo->fd->flags.visited) {
+        /* First time visiting this packet, store previous BLE packet length */
+        p_add_proto_data(wmem_file_scope(), pinfo, proto_nordic_ble, 0, GUINT_TO_POINTER(previous_ble_packet_length));
+    } else {
+        previous_ble_packet_length = GPOINTER_TO_UINT(p_get_proto_data(wmem_file_scope(), pinfo, proto_nordic_ble, 0));
+    }
 
     /* end - start */
     delta_time = (guint32)tvb_get_letohl(tvb, offset);
@@ -279,9 +290,12 @@ dissect_ble_delta_time(tvbuff_t *tvb, gint offset, proto_tree *tree, guint8 pack
 
     /* start - start */
     delta_time_ss = BLE_METADATA_TRANFER_TIME_US + (US_PER_BYTE * previous_ble_packet_length) + delta_time;
-    proto_tree_add_uint(tree, hf_nordic_ble_delta_time_ss, tvb, offset, 4, delta_time_ss);
+    pi = proto_tree_add_uint(tree, hf_nordic_ble_delta_time_ss, tvb, offset, 4, delta_time_ss);
+    PROTO_ITEM_SET_GENERATED(pi);
 
-    previous_ble_packet_length = packet_len;
+    if (!pinfo->fd->flags.visited) {
+        previous_ble_packet_length = packet_len;
+    }
     offset += 4;
 
     return offset;
@@ -355,7 +369,7 @@ dissect_packet(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree,
     proto_tree_add_item(tree, hf_nordic_ble_event_counter, tvb, offset, 2, ENC_LITTLE_ENDIAN);
     offset += 2;
 
-    offset = dissect_ble_delta_time(tvb, offset, tree, packet_len);
+    offset = dissect_ble_delta_time(tvb, offset, pinfo, tree, packet_len);
 
     return offset;
 }
@@ -507,14 +521,14 @@ proto_register_nordic_ble(void)
                 NULL, HFILL }
         },
         { &hf_nordic_ble_delta_time,
-            { "Delta time (us end to start)", "nordic_ble.delta_time",
+            { "Delta time (" UTF8_MICRO_SIGN "s end to start)", "nordic_ble.delta_time",
                 FT_UINT32, BASE_DEC, NULL, 0x0,
-                "Delta time: us since last reported packet", HFILL }
+                UTF8_MICRO_SIGN "s since end of last reported packet", HFILL }
         },
         { &hf_nordic_ble_delta_time_ss,
-            { "Delta time (us start to start)", "nordic_ble.delta_time_ss",
+            { "Delta time (" UTF8_MICRO_SIGN "s start to start)", "nordic_ble.delta_time_ss",
                 FT_UINT32, BASE_DEC, NULL, 0x0,
-                "Delta time: us since start of last reported packet", HFILL }
+                UTF8_MICRO_SIGN "s since start of last reported packet", HFILL }
         }
     };
 
@@ -532,7 +546,7 @@ proto_register_nordic_ble(void)
 
     expert_module_t *expert_nordic_ble;
 
-    proto_nordic_ble = proto_register_protocol("Nordic BLE sniffer meta", "NORDIC_BLE", "nordic_ble");
+    proto_nordic_ble = proto_register_protocol("Nordic BLE Sniffer", "NORDIC_BLE", "nordic_ble");
 
     register_dissector("nordic_ble", dissect_nordic_ble, proto_nordic_ble);