Add an API to let a postdissector specify fields whose values it needs.

Currently, this is only used to determine whether a protocol tree needs
to be built on the first pass or not - if there are postdissectors that
need fields, it does - but eventually we should be able to use it to
prime the dissection to deliver those fields in cases where we don't
need the *entire* protocol tree (rather than using a hack such as
cooking up a fake tap with a fake filter to do that).

Update MATE and TRANSUM to use it.

Clean up code to check whether we need a protocol tree, and add comments
before that code indicating, in each case, what the criteria are.

The array of postdissectors includes a length, so we don't need to
separately keep track of the number of postdissectors.

Clean up indentation while we're at it.

Change-Id: I71d4025848206d144bc54cc82941089a50e80ab7
Reviewed-on: https://code.wireshark.org/review/21029
Reviewed-by: Guy Harris <guy@alum.mit.edu>

2 files changed, 22 insertions, 0 deletions

diff --git a/ui/gtk/packet_list_store.c b/ui/gtk/packet_list_store.c
index 76ffb8e6ec..2ea5d00a81 100644
--- a/ui/gtk/packet_list_store.c
+++ b/ui/gtk/packet_list_store.c
@@ -1148,6 +1148,16 @@ packet_list_dissect_and_cache_record(PacketList *packet_list, PacketListRecord *
 		return;	/* error reading the record */
 	}
 
+	/*
+	 * Determine whether we need to create a protocol tree.
+	 * We do if:
+	 *
+	 *    we're going to apply a color filter to this packet;
+	 *
+	 *    we're need to fill in the columns and we have custom columns
+	 *    (which require field values, which currently requires that
+	 *    we build a protocol tree).
+	 */
 	create_proto_tree = (dissect_color && color_filters_used()) ||
 						(dissect_columns && have_custom_cols(cinfo));
 
diff --git a/ui/qt/packet_list_record.cpp b/ui/qt/packet_list_record.cpp
index 26a444e02b..bf6f866702 100644
--- a/ui/qt/packet_list_record.cpp
+++ b/ui/qt/packet_list_record.cpp
@@ -153,6 +153,18 @@ void PacketListRecord::dissect(capture_file *cap_file, bool dissect_color)
         return;    /* error reading the record */
     }
 
+    /*
+     * Determine whether we need to create a protocol tree.
+     * We do if:
+     *
+     *    we're going to apply a color filter to this packet;
+     *
+     *    we're need to fill in the columns and we have custom columns
+     *    (which require field values, which currently requires that
+     *    we build a protocol tree).
+     *
+     *    XXX - field extractors?  (Not done for GTK+....)
+     */
     create_proto_tree = ((dissect_color && color_filters_used()) ||
                          (dissect_columns && (have_custom_cols(cinfo) ||
                                               have_field_extractors())));