Combine Decode As and port preferences for tcp.port dissector table.

This patch introduces new APIs to allow dissectors to have a preference for
a (TCP) port, but the underlying data is actually part of Decode As functionality.
For now the APIs are intentionally separate from the regular APIs that register a
dissector within a dissector table.  It may be possible to eventually combine the
two so that all dissectors that register with a dissector table have an opportunity
to "automatically" have a preference to adjust the "table value" through the
preferences dialog.

The tcp.port dissector table was used as the guinea pig.  This will eventually be
expanded to other dissector tables as well (most notably UDP ports).  Some
dissectors that "shared" a TCP/UDP port preference were also converted. It also
removed the need for some preference callback functions (mostly when the callback
function was the proto_reg_handoff function) so there is cleanup around that.

Dissectors that has a port preference whose default was 0 were switched to using
the dissector_add_for_decode_as_with_preference API rather than dissector_add_uint_with_preference

Also added comments for TCP ports used that aren't IANA registered.

Change-Id: I99604f95d426ad345f4b494598d94178b886eb67
Reviewed-on: https://code.wireshark.org/review/17724
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 154 insertions, 5 deletions

diff --git a/epan/packet.c b/epan/packet.c
index ad3ef1d9c2..4a248821bf 100644
--- a/epan/packet.c
+++ b/epan/packet.c
@@ -47,6 +47,7 @@
 #include <epan/reassemble.h>
 #include <epan/stream.h>
 #include <epan/expert.h>
+#include <epan/prefs.h>
 #include <epan/range.h>
 #include <epan/asm_utils.h>
 
@@ -987,12 +988,112 @@ void dissector_add_uint_range(const char *abbrev, range_t *range,
 	guint32 i, j;
 
 	if (range) {
-		for (i = 0; i < range->nranges; i++) {
-			for (j = range->ranges[i].low; j < range->ranges[i].high; j++)
-				dissector_add_uint(abbrev, j, handle);
-			dissector_add_uint(abbrev, range->ranges[i].high, handle);
+		if (range->nranges == 0) {
+			/* Even an empty range would want a chance for Decode As */
+			dissector_add_for_decode_as(abbrev, handle);
+		}
+		else {
+			for (i = 0; i < range->nranges; i++) {
+				for (j = range->ranges[i].low; j < range->ranges[i].high; j++)
+					dissector_add_uint(abbrev, j, handle);
+				dissector_add_uint(abbrev, range->ranges[i].high, handle);
+			}
+		}
+	}
+}
+
+static void
+dissector_add_preference(const char *name, dissector_handle_t handle, guint init_value)
+{
+	guint* uint_var;
+	module_t *module;
+	gchar *description, *title;
+	dissector_table_t  pref_dissector_table = find_dissector_table( name);
+	int proto_id = proto_get_id(handle->protocol);
+
+	uint_var = wmem_new(wmem_epan_scope(), guint);
+	*uint_var = init_value;
+
+	/* If the dissector already has a preference module, use it */
+	module = prefs_find_module(proto_get_protocol_filter_name(proto_id));
+	if (module == NULL)
+	{
+		/* Otherwise create a new one */
+		module = prefs_register_protocol(proto_id, NULL);
+	}
+
+	description = wmem_strdup_printf(wmem_epan_scope(), "Set the %s for %s (if other than the default of %u)",
+									pref_dissector_table->ui_name, proto_get_protocol_short_name(handle->protocol), *uint_var);
+	title = wmem_strdup_printf(wmem_epan_scope(), "%s %s", proto_get_protocol_short_name(handle->protocol),
+									pref_dissector_table->ui_name);
+
+	prefs_register_decode_as_preference(module, name, title, description, uint_var);
+}
+
+void dissector_add_uint_with_preference(const char *name, const guint32 pattern,
+    dissector_handle_t handle)
+{
+	dissector_add_preference(name, handle, pattern);
+	dissector_add_uint(name, pattern, handle);
+}
+
+void dissector_add_uint_range_with_preference(const char *abbrev, const char* range_str,
+    dissector_handle_t handle)
+{
+	range_t** range;
+	module_t *module;
+	gchar *description, *title;
+	dissector_table_t  pref_dissector_table = find_dissector_table( abbrev);
+	int proto_id = proto_get_id(handle->protocol);
+	guint32 max_value = 0;
+
+	/* If a dissector is added for Decode As only, it's dissector
+		table value would default to 0.
+		Set up a preference value with that information
+	 */
+	range = wmem_new(wmem_epan_scope(), range_t*);
+	*range = range_empty();
+
+	/* If the dissector already has a preference module, use it */
+	module = prefs_find_module(proto_get_protocol_filter_name(proto_id));
+	if (module == NULL) {
+		/* Otherwise create a new one */
+		module = prefs_register_protocol(proto_id, NULL);
+	}
+	/* Some preference callback functions use the proto_reg_handoff_
+		routine to apply preferences, which could duplicate the
+		registration of a preference.  Check for that here */
+	else if (prefs_find_preference(module, abbrev) == NULL) {
+		description = wmem_strdup_printf(wmem_epan_scope(), "%s %s(s)",
+									    proto_get_protocol_short_name(handle->protocol), pref_dissector_table->ui_name);
+		title = wmem_strdup_printf(wmem_epan_scope(), "%s(s)", pref_dissector_table->ui_name);
+
+		/* Max value is based on datatype of dissector table */
+		switch (pref_dissector_table->type) {
+
+		case FT_UINT8:
+			max_value = 0xFF;
+			break;
+		case FT_UINT16:
+			max_value = 0xFFFF;
+			break;
+		case FT_UINT24:
+			max_value = 0xFFFFFF;
+			break;
+		case FT_UINT32:
+			max_value = 0xFFFFFFFF;
+			break;
+
+		default:
+			g_error("The dissector table %s (%s) is not an integer type - are you using a buggy plugin?", abbrev, pref_dissector_table->ui_name);
+			g_assert_not_reached();
 		}
+
+		range_convert_str(range, range_str, max_value);
+		prefs_register_decode_as_range_preference(module, abbrev, title, description, range, max_value);
 	}
+
+	dissector_add_uint_range(abbrev, *range, handle);
 }
 
 /* Delete the entry for a dissector in a uint dissector table
@@ -1831,6 +1932,18 @@ dissector_add_for_decode_as(const char *name, dissector_handle_t handle)
 		g_slist_insert_sorted(sub_dissectors->dissector_handles, (gpointer)handle, (GCompareFunc)dissector_compare_filter_name);
 }
 
+void dissector_add_for_decode_as_with_preference(const char *name,
+    dissector_handle_t handle)
+{
+	/* If a dissector is added for Decode As only, it's dissector
+	   table value would default to 0.
+	   Set up a preference value with that information
+	 */
+	dissector_add_preference(name, handle, 0);
+
+	dissector_add_for_decode_as(name, handle);
+}
+
 dissector_handle_t
 dtbl_entry_get_initial_handle (dtbl_entry_t *dtbl_entry)
 {
@@ -1839,10 +1952,46 @@ dtbl_entry_get_initial_handle (dtbl_entry_t *dtbl_entry)
 
 GSList *
 dissector_table_get_dissector_handles(dissector_table_t dissector_table) {
-	if (!dissector_table) return NULL;
+	if (!dissector_table)
+		return NULL;
+
 	return dissector_table->dissector_handles;
 }
 
+/*
+ * Data structure used as user data when iterating dissector handles
+ */
+typedef struct lookup_entry {
+	gchar*             dissector_short_name;
+	dissector_handle_t handle;
+} lookup_entry_t;
+
+/*
+ * A callback function to changed a dissector_handle if matched
+ * This is used when iterating a dissector table
+ */
+static void
+find_dissector_in_table(gpointer item, gpointer user_data)
+{
+	dissector_handle_t handle = (dissector_handle_t)item;
+	lookup_entry_t * lookup = (lookup_entry_t *)user_data;
+	const gchar *proto_short_name = dissector_handle_get_short_name(handle);
+	if (proto_short_name && strcmp(lookup->dissector_short_name, proto_short_name) == 0) {
+		lookup->handle = handle;
+	}
+}
+
+dissector_handle_t dissector_table_get_dissector_handle(dissector_table_t dissector_table, gchar* short_name)
+{
+	lookup_entry_t lookup;
+
+	lookup.dissector_short_name = short_name;
+	lookup.handle = NULL;
+
+	g_slist_foreach(dissector_table->dissector_handles, find_dissector_in_table, &lookup);
+	return lookup.handle;
+}
+
 ftenum_t
 dissector_table_get_type(dissector_table_t dissector_table) {
 	if (!dissector_table) return FT_NONE;