Don't allow multiple registrations of a protocol in dissector tables.

The target here is the Decode As dialog where protocols have multiple registrations into a dissector table and that shows up as multiple entries in the Decode As dialog list with the same name so users are unsure which "dissector" they are choosing.

The "default" behavior (done in this commit) is to not allow duplicates for a dissector table, whether its part of Decode As or not.  It's just ENFORCED for Decode As.

Bug: 3949
Change-Id: Ibe14fa61aaeca0881f9cc39b78799e314b5e8127
Reviewed-on: https://code.wireshark.org/review/11405
Petri-Dish: Michael Mann <mmann78@netscape.net>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 29 insertions, 2 deletions

diff --git a/epan/packet.c b/epan/packet.c
index 465229016c..efd13b8135 100644
--- a/epan/packet.c
+++ b/epan/packet.c
@@ -95,6 +95,7 @@ struct dissector_table {
 	ftenum_t	type;
 	int		param;
 	GHashFunc hash_func;
+	dissector_table_allow_e allow_dup_proto; /* XXX - Could be converted to a flag-like field */
 };
 
 static GHashTable *dissector_tables = NULL;
@@ -1711,6 +1712,7 @@ dissector_add_for_decode_as(const char *name, dissector_handle_t handle)
 {
 	dissector_table_t  sub_dissectors = find_dissector_table( name);
 	GSList            *entry;
+	dissector_handle_t dup_handle;
 
 	/*
 	 * Make sure the dissector table exists.
@@ -1734,6 +1736,22 @@ dissector_add_for_decode_as(const char *name, dissector_handle_t handle)
 		return;
 	}
 
+	/* Ensure the protocol is unique.  This prevents confusion when using Decode As
+	   with duplicative entires */
+	if (sub_dissectors->allow_dup_proto == DISSECTOR_TABLE_NOT_ALLOW_DUPLICATE)
+	{
+		for (entry = sub_dissectors->dissector_handles; entry != NULL; entry = g_slist_next(entry))
+		{
+			dup_handle = (dissector_handle_t)entry->data;
+			if (dup_handle->protocol == handle->protocol)
+			{
+				fprintf(stderr, "Duplicative protocol %s in %s\n", proto_get_protocol_short_name(handle->protocol), name);
+				if (getenv("WIRESHARK_ABORT_ON_DISSECTOR_BUG") != NULL)
+					abort();
+			}
+		}
+	}
+
 	/* Add it to the list. */
 	sub_dissectors->dissector_handles =
 		g_slist_insert_sorted(sub_dissectors->dissector_handles, (gpointer)handle, (GCompareFunc)dissector_compare_filter_name);
@@ -1757,6 +1775,13 @@ dissector_table_get_type(dissector_table_t dissector_table) {
 	return dissector_table->type;
 }
 
+dissector_table_allow_e
+dissector_table_get_proto_allowed(dissector_table_t dissector_table)
+{
+	if (!dissector_table) return DISSECTOR_TABLE_NOT_ALLOW_DUPLICATE;
+	return dissector_table->allow_dup_proto;
+}
+
 static gint
 uuid_equal(gconstpointer k1, gconstpointer k2)
 {
@@ -2015,7 +2040,7 @@ dissector_all_tables_foreach_table (DATFunc_table func,
 
 dissector_table_t
 register_dissector_table(const char *name, const char *ui_name, const ftenum_t type,
-			 const int param)
+			 const int param, dissector_table_allow_e allow_dup)
 {
 	dissector_table_t	sub_dissectors;
 
@@ -2066,12 +2091,13 @@ register_dissector_table(const char *name, const char *ui_name, const ftenum_t t
 	sub_dissectors->ui_name = ui_name;
 	sub_dissectors->type    = type;
 	sub_dissectors->param   = param;
+	sub_dissectors->allow_dup_proto   = allow_dup;
 	g_hash_table_insert( dissector_tables, (gpointer)name, (gpointer) sub_dissectors );
 	return sub_dissectors;
 }
 
 dissector_table_t register_custom_dissector_table(const char *name,
-    const char *ui_name, GHashFunc hash_func, GEqualFunc key_equal_func)
+	const char *ui_name, GHashFunc hash_func, GEqualFunc key_equal_func, dissector_table_allow_e allow_dup)
 {
 	dissector_table_t	sub_dissectors;
 
@@ -2093,6 +2119,7 @@ dissector_table_t register_custom_dissector_table(const char *name,
 	sub_dissectors->ui_name = ui_name;
 	sub_dissectors->type    = FT_BYTES; /* Consider key a "blob" of data, no need to really create new type */
 	sub_dissectors->param   = BASE_NONE;
+	sub_dissectors->allow_dup_proto   = allow_dup;
 	g_hash_table_insert( dissector_tables, (gpointer)name, (gpointer) sub_dissectors );
 	return sub_dissectors;
 }