Recompile dfilter for all tap listeners when fields changed

When fields have changed the compiled display filter may be invalid
or need a recompile to be valid.

Filters which are not valid after a recompile is set to a filter
matching no packets (frame.number == 0) to indicate that this does
no longer match anything.  We should probably have a better filter
matching no packet for this purpose.

Change-Id: Id27efa9f46e77e20df50d7366f26d5cada186f93
Reviewed-on: https://code.wireshark.org/review/10123
Petri-Dish: Stig Bjørlykke <stig@bjorlykke.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Stig Bjørlykke <stig@bjorlykke.org>

3 files changed, 34 insertions, 0 deletions

diff --git a/epan/tap.c b/epan/tap.c
index c0b7f92c2f..d1e68fd73e 100644
--- a/epan/tap.c
+++ b/epan/tap.c
@@ -93,6 +93,7 @@ typedef struct _tap_listener_t {
 	int tap_id;
 	gboolean needs_redraw;
 	guint flags;
+	gchar *fstring;
 	dfilter_t *code;
 	void *tapdata;
 	tap_reset_cb reset;
@@ -529,6 +530,7 @@ register_tap_listener(const char *tapname, void *tapdata, const char *fstring,
 			return error_string;
 		}
 	}
+	tl->fstring=g_strdup(fstring);
 
 	tl->tap_id=tap_id;
 	tl->tapdata=tapdata;
@@ -573,8 +575,10 @@ set_tap_dfilter(void *tapdata, const char *fstring)
 			tl->code=NULL;
 		}
 		tl->needs_redraw=TRUE;
+		g_free(tl->fstring);
 		if(fstring){
 			if(!dfilter_compile(fstring, &tl->code, &err_msg)){
+				tl->fstring=NULL;
 				error_string = g_string_new("");
 				g_string_printf(error_string,
 						 "Filter \"%s\" is invalid - %s",
@@ -583,11 +587,36 @@ set_tap_dfilter(void *tapdata, const char *fstring)
 				return error_string;
 			}
 		}
+		tl->fstring=g_strdup(fstring);
 	}
 
 	return NULL;
 }
 
+/* this function recompiles dfilter for all registered tap listeners
+ */
+void
+tap_listeners_dfilter_recompile(void)
+{
+	tap_listener_t *tl;
+	gchar *err_msg;
+
+	for(tl=(tap_listener_t *)tap_listener_queue;tl;tl=tl->next){
+		if(tl->code){
+			dfilter_free(tl->code);
+			tl->code=NULL;
+		}
+		tl->needs_redraw=TRUE;
+		if(tl->fstring){
+			if(!dfilter_compile(tl->fstring, &tl->code, &err_msg)){
+				g_free(err_msg);
+				/* Not valid, make a dfilter matching no packets */
+				dfilter_compile("frame.number == 0", &tl->code, &err_msg);
+			}
+		}
+	}
+}
+
 /* this function removes a tap listener
  */
 void
@@ -617,6 +646,7 @@ remove_tap_listener(void *tapdata)
 		if(tl->code){
 			dfilter_free(tl->code);
 		}
+		g_free(tl->fstring);
 		g_free(tl);
 	}
 
diff --git a/epan/tap.h b/epan/tap.h
index 7f2002af17..c3b427f008 100644
--- a/epan/tap.h
+++ b/epan/tap.h
@@ -218,6 +218,9 @@ WS_DLL_PUBLIC GString *register_tap_listener(const char *tapname, void *tapdata,
 /** This function sets a new dfilter to a tap listener */
 WS_DLL_PUBLIC GString *set_tap_dfilter(void *tapdata, const char *fstring);
 
+/** This function recompiles dfilter for all registered tap listeners */
+WS_DLL_PUBLIC void tap_listeners_dfilter_recompile(void);
+
 /** this function removes a tap listener */
 WS_DLL_PUBLIC void remove_tap_listener(void *tapdata);
 
diff --git a/ui/qt/main_window_slots.cpp b/ui/qt/main_window_slots.cpp
index a98a84cba9..fd7a1817ac 100644
--- a/ui/qt/main_window_slots.cpp
+++ b/ui/qt/main_window_slots.cpp
@@ -1308,6 +1308,7 @@ void MainWindow::redissectPackets()
 void MainWindow::fieldsChanged()
 {
     color_filters_reload();
+    tap_listeners_dfilter_recompile();
 
     if (!df_combo_box_->checkDisplayFilter()) {
         g_free(CaptureFile::globalCapFile()->dfilter);