Add a mechanism by which a dissector can be registered by name, another

dissector can get a "handle" for that dissector by name and then call
that dissector through the handle.

This allows dissectors that can't be called through a port table or a
heuristic table to be called from other dissectors without directly
referring to the dissector function - dynamically-loaded modules, under
Windows, cannot directly call functions in the main program, and
non-plugin dissectors are in the main program and thus cannot be called
from plugin dissectors unless either

	1) a pointer to the dissector is put in the Big Transfer Vector

or

	2) some other mechanism for getting a pointer to the dissector
	   is provided.

This mechanism could also support registering old-style dissectors and
calling them from new-style dissectors without the new-style dissector
having to do the argument translation itself (I didn't add support for
registering old-style dissectors because I'd prefer to have people
tvbuffify their code if they have to register a dissector...).

It could also, in the future, perhaps support

	disabling of protocols;

	setting "pinfo->current_proto";

inside "call_dissector()" - and inside "{old_}dissector_try_port()" and
"{old_"dissector_try_heuristic()" - allowing a pile of stuff that
currently has to be done in every dissector be done by common code.
(I have some ideas about how to do this, by

	having "proto_register_protocol()" take an abbreviation - of the
	sort that would be put in, for example, "pinfo->current_proto" -
	as an argument;

	having the calls to register dissectors take an index returned
	by "proto_register_protocol()" as an argument.

The abbreviation could be used elsewhere as well, e.g. in the "Decoding"
tab of the "Edit->Protocols" dialog box, and in a GUI for constructing
protocol filters.  Watch this space.)

Make "dissect_sdp()" the first client of this mechanism; it's now static
to "packet-sdp.c", and all dissectors that call it - including the MGCP
plugin - now call it through a dissector handle fetched by
"find_dissector()".  (Next step - see if Ethereal can now compile on
Windows as a result of this.)

svn path=/trunk/; revision=2647

1 files changed, 6 insertions, 1 deletions

diff --git a/plugins/plugin_api.h b/plugins/plugin_api.h
index c93d4606ef..d2125a66de 100644
--- a/plugins/plugin_api.h
+++ b/plugins/plugin_api.h
@@ -1,7 +1,7 @@
 /* plugin_api.h
  * Routines for Ethereal plugins.
  *
- * $Id: plugin_api.h,v 1.11 2000/11/14 10:38:13 guy Exp $
+ * $Id: plugin_api.h,v 1.12 2000/11/15 07:07:50 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * Copyright 2000 by Gilbert Ramirez <gram@xiexie.org>
@@ -57,6 +57,11 @@
 
 #define	heur_dissector_add		(*p_heur_dissector_add)
 
+#define register_dissector		(*p_register_dissector)
+#define find_dissector			(*p_find_dissector)
+#define old_call_dissector		(*p_old_call_dissector)
+#define call_dissector			(*p_call_dissector)
+
 #define dissect_data			(*p_dissect_data)
 #define old_dissect_data		(*p_old_dissect_data)