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, 9 insertions, 3 deletions

diff --git a/packet-rtsp.c b/packet-rtsp.c
index d0699262c9..869672e02b 100644
--- a/packet-rtsp.c
+++ b/packet-rtsp.c
@@ -4,7 +4,7 @@
  * Jason Lango <jal@netapp.com>
  * Liberally copied from packet-http.c, by Guy Harris <guy@alum.mit.edu>
  *
- * $Id: packet-rtsp.c,v 1.25 2000/11/13 08:58:10 guy Exp $
+ * $Id: packet-rtsp.c,v 1.26 2000/11/15 07:07:43 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@zing.org>
@@ -39,7 +39,6 @@
 
 #include <glib.h>
 #include "packet.h"
-#include "packet-sdp.h"
 #include "packet-rtp.h"
 #include "packet-rtcp.h"
 #include "conversation.h"
@@ -74,6 +73,8 @@ static const char *rtsp_methods[] = {
 
 #define RTSP_NMETHODS	(sizeof rtsp_methods / sizeof rtsp_methods[0])
 
+static dissector_handle_t sdp_handle;
+
 static rtsp_type_t
 is_rtsp_request_or_reply(const u_char *line, int linelen)
 {
@@ -359,7 +360,7 @@ dissect_rtsp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 			 * dissect it.
 			 */
 			new_tvb = tvb_new_subset(tvb, offset, -1, -1);
-			dissect_sdp(new_tvb, pinfo, tree);
+			call_dissector(sdp_handle, new_tvb, pinfo, tree);
 		}
 	} else {
 		if (datalen > 0) {
@@ -463,4 +464,9 @@ void
 proto_reg_handoff_rtsp(void)
 {
 	dissector_add("tcp.port", TCP_PORT_RTSP, dissect_rtsp);
+
+	/*
+	 * Get a handle for the SDP dissector.
+	 */
+	sdp_handle = find_dissector("sdp");
 }