handle usbpcap traces

1 files changed, 13 insertions, 7 deletions

diff --git a/usb/ncr-dispenser.lua b/usb/ncr-dispenser.lua
index c81b085..8494b11 100644
--- a/usb/ncr-dispenser.lua
+++ b/usb/ncr-dispenser.lua
@@ -1,4 +1,5 @@
 -- declare some Fields to be read
+usb_hl_f = Field.new("usb.usbpcap_header_len")
 usb_tt_f = Field.new("usb.transfer_type")
 usb_dl_f = Field.new("usb.data_len")
 
@@ -31,18 +32,23 @@ dispenser_proto.fields = {
 -- create a function to "postdissect" each frame
 function dispenser_proto.dissector(buffer,pinfo,tree)
     -- obtain the current values the protocol fields
+    local usb_hl = usb_hl_f()
     local usb_tt = usb_tt_f()
     local usb_dl = usb_dl_f()
     if usb_tt.value == 0x01 and usb_dl.value >= 63 then
-        local magic = buffer(64 +  8,2)
+        local off = 64
+	if usb_hl then
+	    off = usb_hl.value
+	end
+        local magic = buffer(off +  8,2)
         if magic:le_uint() == 0xbeef then
             local subtree = tree:add(dispenser_proto, "NCR S1 Dispenser")
-            subtree:add(u00_00_F, buffer(64 +  0x00,1))
-            subtree:add(u01_07_F, buffer(64 +  0x01,7))
-            subtree:add_le( magic_F, magic)
-            subtree:add(u0a_0f_F, buffer(64 +  0x0a,6))
-            subtree:add(u10_17_F, buffer(64 +  0x10,8))
-            subtree:add(u18_1f_F, buffer(64 +  0x18,8))
+            subtree:add(u00_00_F, buffer(off + 0x00,1))
+            subtree:add(u01_07_F, buffer(off + 0x01,7))
+            subtree:add_le(magic_F, magic)
+            subtree:add(u0a_0f_F, buffer(off + 0x0a,6))
+            subtree:add(u10_17_F, buffer(off + 0x10,8))
+            subtree:add(u18_1f_F, buffer(off + 0x18,8))
         end
     end
 end