New Lua function TreeItem:referenced(ProtoField | Dissector).

This function returns TRUE/FALSE depending whether the specified ProtoField/Dissector
needs to be dissected. By using this function in conjunction with the TreeItem.visible
attribute, Lua dissectors can be significantly sped up by making less C interop calls
which are relatively slow in terms of dissection especially when using sub-protocols
where the dissection of an entire protocol can be skipped.

Added tests for TreeItem:referenced to protofield.lua

Change-Id: I44feacb91a2a5b0e3c28c0ccd8d6b04cccd67261
Reviewed-on: https://code.wireshark.org/review/21387
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

2 files changed, 34 insertions, 9 deletions

diff --git a/test/lua/protofield.lua b/test/lua/protofield.lua
index c4026e5cf8..6b6110ddff 100644
--- a/test/lua/protofield.lua
+++ b/test/lua/protofield.lua
@@ -30,7 +30,7 @@ local function setFailed(name)
 end
 
 -- expected number of runs
-local taptests = { [OTHER]=28 }
+local taptests = { [OTHER]=32 }
 local function getResults()
     print("\n-----------------------------\n")
     for k,v in pairs(taptests) do
@@ -70,6 +70,7 @@ end
 local test_proto = Proto.new("test", "Test Proto")
 test_proto.fields.time_field = ProtoField.uint16("test.time", "Time", base.UNIT_STRING, {" sec", " secs"})
 test_proto.fields.dist_field = ProtoField.uint16("test.dist", "Distance", base.UNIT_STRING, {" km"})
+test_proto.fields.filtered_field = ProtoField.uint16("test.filtered", "Filtered Field", base.DEC)
 
 -- Field name: empty, illegal, incompatible
 success = pcall(ProtoField.int8, nil, "empty field name 1")
@@ -155,6 +156,19 @@ function test_proto.dissector(tvb, pinfo, tree)
     test("Time: 65535 secs", ti.text == "Time: 65535 secs")
     ti = tree:add(test_proto.fields.dist_field, tvb3())
     test("Distance: 65535 km", ti.text == "Distance: 65535 km")
+
+    ti = tree:add(test_proto.fields.filtered_field, tvb2())
+    -- Note that this file should be loaded in tshark twice. Once with a visible
+    -- tree (-V) and once without a visible tree.
+    if tree.visible then
+        -- Tree is visible so both fields should be referenced
+        test("Visible tree: Time is referenced", tree:referenced(test_proto.fields.time_field) == true)
+        test("Visible tree: Filtered field is referenced", tree:referenced(test_proto.fields.filtered_field) == true)
+    else
+        -- Tree is not visible so only the field that appears in a filter should be referenced
+        test("Invisible tree: Time is NOT referenced", tree:referenced(test_proto.fields.time_field) == false)
+        test("Invisible tree: Filtered field is referenced", tree:referenced(test_proto.fields.filtered_field) == true)
+    end
 end
 
 DissectorTable.get("udp.port"):add(65333, test_proto)
diff --git a/test/suite-wslua.sh b/test/suite-wslua.sh
index c788a7d81c..20745f449a 100755
--- a/test/suite-wslua.sh
+++ b/test/suite-wslua.sh
@@ -340,14 +340,25 @@ wslua_step_protofield_test() {
 		return
 	fi
 
-    # Tshark catches lua script failures, so we have to parse the output.
-    $TSHARK -r $CAPTURE_DIR/dns_port.pcap -X lua_script:$TESTS_DIR/lua/protofield.lua -V > testout.txt 2>&1
-    if grep -q "All tests passed!" testout.txt; then
-        test_step_ok
-    else
-        cat testout.txt
-        test_step_failed "didn't find pass marker"
-    fi
+	# Tshark catches lua script failures, so we have to parse the output.
+	# Perform this twice: once with a tree, once without
+
+	# Pass 1 (visible tree)
+	$TSHARK -r $CAPTURE_DIR/dns_port.pcap -X lua_script:$TESTS_DIR/lua/protofield.lua -V -Y "test.filtered==1" > testout.txt 2>&1
+	grep -q "All tests passed!" testout.txt
+	if [ $? -ne 0 ]; then
+		cat testout.txt
+		test_step_failed "protofield_test: didn't find pass marker (pass 1)"
+	fi
+
+	# Pass 2 (invisible tree)
+	$TSHARK -r $CAPTURE_DIR/dns_port.pcap -X lua_script:$TESTS_DIR/lua/protofield.lua -Y "test.filtered==1" > testout.txt 2>&1
+	if grep -q "All tests passed!" testout.txt; then
+		test_step_ok
+	else
+		cat testout.txt
+		test_step_failed "protofield_test: didn't find pass marker (pass 2)"
+	fi
 }
 
 wslua_step_int64_test() {