Qt: Add check for field extractors

The proto tree is needed in several cases when using Lua field extractors,
because they fetch values from the tree.  Without a valid field extractor
a Lua plugin may misbehave and display wrong column info.

This fixes column issues when:
- Calling resetColumns() in Qt.  This involves adding a display filter,
  change time display format, change name resolution and other changes
  in UI which requires column updates.
- Print summary lines.
- Export as CSV and PSML.

Change-Id: Ieed6f8578cdf2759f1f836cd8413a4529b7bbd80
Reviewed-on: https://code.wireshark.org/review/13708
Petri-Dish: Stig Bjørlykke <stig@bjorlykke.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

debian/libwireshark0.symbols

@@ -768,6 +768,7 @@ libwireshark.so.0 libwireshark0 #MINVER#
  has_heur_dissector_list@Base 1.12.0~rc1
  have_custom_cols@Base 1.9.1
  have_filtering_tap_listeners@Base 1.9.1
+ have_field_extractors@Base 2.0.2
  have_tap_listener@Base 1.12.0~rc1
  heur_dissector_add@Base 1.9.1
  heur_dissector_delete@Base 1.9.1

epan/column-utils.c

@@ -43,6 +43,10 @@
 #include <epan/dfilter/dfilter.h>
 #include <wsutil/utf8_entities.h>
 
+#ifdef HAVE_LUA
+#include <epan/wslua/wslua.h>
+#endif
+
 /* Allocate all the data structures for constructing column data, given
    the number of columns. */
 void
@@ -292,6 +296,16 @@ have_custom_cols(column_info *cinfo)
   return HAVE_CUSTOM_COLS(cinfo);
 }
 
+gboolean
+have_field_extractors(void)
+{
+#ifdef HAVE_LUA
+    return wslua_has_field_extractors();
+#else
+    return FALSE;
+#endif
+}
+
 /* search in edt tree custom fields */
 void col_custom_set_edt(epan_dissect_t *edt, column_info *cinfo)
 {

epan/column-utils.h

@@ -241,6 +241,11 @@ void col_custom_prime_edt(struct epan_dissect *edt, column_info *cinfo);
 /** For internal Wireshark use only.  Not to be called from dissectors. */
 WS_DLL_PUBLIC
 gboolean have_custom_cols(column_info *cinfo);
+
+/** For internal Wireshark use only.  Not to be called from dissectors. */
+WS_DLL_PUBLIC
+gboolean have_field_extractors(void);
+
 /** For internal Wireshark use only.  Not to be called from dissectors. */
 WS_DLL_PUBLIC
 gboolean col_has_time_fmt(column_info *cinfo, const gint col);

epan/dfilter/dfilter.c

@@ -415,6 +415,12 @@ dfilter_prime_proto_tree(const dfilter_t *df, proto_tree *tree)
 	}
 }
 
+gboolean
+dfilter_has_interesting_fields(const dfilter_t *df)
+{
+	return (df->num_interesting_fields > 0);
+}
+
 GPtrArray *
 dfilter_deprecated_tokens(dfilter_t *df) {
 	if (df->deprecated && df->deprecated->len > 0) {

epan/dfilter/dfilter.h

@@ -80,6 +80,10 @@ dfilter_apply(dfilter_t *df, proto_tree *tree);
 void
 dfilter_prime_proto_tree(const dfilter_t *df, proto_tree *tree);
 
+/* Check if dfilter has interesting fields */
+gboolean
+dfilter_has_interesting_fields(const dfilter_t *df);
+
 WS_DLL_PUBLIC
 GPtrArray *
 dfilter_deprecated_tokens(dfilter_t *df);

epan/wslua/wslua.h

@@ -710,6 +710,7 @@ extern void wslua_prefs_changed(void);
 extern void proto_register_lua(void);
 extern GString* lua_register_all_taps(void);
 extern void wslua_prime_dfilter(epan_dissect_t *edt);
+extern gboolean wslua_has_field_extractors(void);
 extern void lua_prime_all_fields(proto_tree* tree);
 
 extern int Proto_commit(lua_State* L);

epan/wslua/wslua_field.c

@@ -551,6 +551,11 @@ void wslua_prime_dfilter(epan_dissect_t *edt) {
     }
 }
 
+/* Check if we have any registered field extractors. */
+gboolean wslua_has_field_extractors(void) {
+    return (wslua_dfilter && dfilter_has_interesting_fields(wslua_dfilter));
+}
+
 /*
  * field extractor registration is tricky, In order to allow
  * the user to define them in the body of the script we will

file.c

@@ -2469,7 +2469,7 @@ cf_print_packets(capture_file *cf, print_args_t *print_args)
   proto_tree_needed =
       callback_args.print_args->print_dissections != print_dissections_none ||
       callback_args.print_args->print_hex ||
-      have_custom_cols(&cf->cinfo);
+      have_custom_cols(&cf->cinfo) || have_field_extractors();
   epan_dissect_init(&callback_args.edt, cf->epan, proto_tree_needed, proto_tree_needed);
 
   /* Iterate through the list of packets, printing the packets we were
@@ -2641,8 +2641,8 @@ cf_write_psml_packets(capture_file *cf, print_args_t *print_args)
   callback_args.fh = fh;
 
   /* Fill in the column information, only create the protocol tree
-     if having custom columns. */
-  proto_tree_needed = have_custom_cols(&cf->cinfo);
+     if having custom columns or field extractors. */
+  proto_tree_needed = have_custom_cols(&cf->cinfo) || have_field_extractors();
   epan_dissect_init(&callback_args.edt, cf->epan, proto_tree_needed, proto_tree_needed);
 
   /* Iterate through the list of packets, printing the packets we were
@@ -2721,8 +2721,8 @@ cf_write_csv_packets(capture_file *cf, print_args_t *print_args)
 
   callback_args.fh = fh;
 
-  /* only create the protocol tree if having custom columns. */
-  proto_tree_needed = have_custom_cols(&cf->cinfo);
+  /* only create the protocol tree if having custom columns or field extractors. */
+  proto_tree_needed = have_custom_cols(&cf->cinfo) || have_field_extractors();
   epan_dissect_init(&callback_args.edt, cf->epan, proto_tree_needed, proto_tree_needed);
 
   /* Iterate through the list of packets, printing the packets we were

ui/qt/packet_list_record.cpp

@@ -133,8 +133,9 @@ void PacketListRecord::dissect(capture_file *cap_file, bool dissect_color)
         return;    /* error reading the record */
     }
 
-    create_proto_tree = (dissect_color && color_filters_used()) ||
-                        (dissect_columns && have_custom_cols(cinfo));
+    create_proto_tree = ((dissect_color && color_filters_used()) ||
+                         (dissect_columns && (have_custom_cols(cinfo) ||
+                                              have_field_extractors())));
 
     epan_dissect_init(&edt, cap_file->epan,
                       create_proto_tree,