From Tobias Erichsen:

RTP-MIDI - dissector for transmission of MIDI-commands via RTP (RFC 4695).

https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5451

svn path=/trunk/; revision=41200

1 files changed, 136 insertions, 37 deletions

diff --git a/epan/dissectors/packet-applemidi.c b/epan/dissectors/packet-applemidi.c
index e212d9aa3e..edf355546c 100644
--- a/epan/dissectors/packet-applemidi.c
+++ b/epan/dissectors/packet-applemidi.c
@@ -1,6 +1,6 @@
 /* packet-applemidi.c
  * Routines for dissection of Apple network-midi session establishment.
- * Copyright 2006-2010, Tobias Erichsen <t.erichsen@gmx.de>
+ * Copyright 2006-2012, Tobias Erichsen <t.erichsen@gmx.de>
  *
  * $Id$
  *
@@ -25,17 +25,27 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  *
  *
- * Apple network-midi session establishment is a lightweight protocol for providing
- * a simple session establishment for MIDI-data sent in the form of RTP-MIDI (RFC 4695)
- * Peers recognize each other using the Apple Bonjour scheme with the service-name
- * "_apple-midi._udp", establish a connection using AppleMIDI (no official name, just
- * an abbreviation) and then send payload using RTP-MIDI.  The implementation of
- * this dissector is based on the Apple implementation summary from May 6th, 2005.
+ * Apple network-midi session establishment is a lightweight protocol for
+ * providing a simple session establishment for MIDI-data sent in the form
+ * of RTP-MIDI (RFC 4695 / 6295).  Peers recognize each other using the
+ * Apple Bonjour scheme with the service-name "_apple-midi._udp", establish
+ * a connection using AppleMIDI (no official name, just an abbreviation)
+ * and then send payload using RTP-MIDI.  The implementation of this
+ * dissector is based on the Apple implementation summary from May 6th, 2005
+ * and the extension from August 13th, 2010.
+ *
+ * 2010-11-29
+ * - initial version of dissector
+ * 2012-02-24
+ * - implemented dynamic payloadtype support to automatically punt
+ *   the decoding to the RTP-MIDI dissector via the RTP dissector
+ * - added new bitrate receive limit feature
  *
  * Here are some links:
  *
  * http://www.cs.berkeley.edu/~lazzaro/rtpmidi/
  * http://www.faqs.org/rfcs/rfc4695.html
+ * http://www.faqs.org/rfcs/rfc6295.html
  */
 
 #ifdef HAVE_CONFIG_H
@@ -46,22 +56,24 @@
 #include <epan/packet.h>
 #include <epan/conversation.h>
 
+#include "packet-rtp.h"
+
 /* Definitions for protocol name during dissector-register */
 #define APPLEMIDI_DISSECTOR_NAME			"Apple Network-MIDI Session Protocol"
-#define APPLEMIDI_DISSECTOR_SHORTNAME		"AppleMIDI"
-#define APPLEMIDI_DISSECTOR_ABBREVIATION	"applemidi"
+#define APPLEMIDI_DISSECTOR_SHORTNAME			"AppleMIDI"
+#define APPLEMIDI_DISSECTOR_ABBREVIATION		"applemidi"
 
 /* Signature "Magic Value" for Apple network MIDI session establishment */
 #define APPLEMIDI_PROTOCOL_SIGNATURE			0xffff
 
 /* Apple network MIDI valid commands */
 #define APPLEMIDI_COMMAND_INVITATION			0x494e		/*   "IN"   */
-#define APPLEMIDI_COMMAND_INVITATION_REJECTED	0x4e4f		/*   "NO"   */
-#define APLLEMIDI_COMMAND_INVITATION_ACCEPTED	0x4f4b		/*   "OK"   */
+#define APPLEMIDI_COMMAND_INVITATION_REJECTED		0x4e4f		/*   "NO"   */
+#define APLLEMIDI_COMMAND_INVITATION_ACCEPTED		0x4f4b		/*   "OK"   */
 #define APPLEMIDI_COMMAND_ENDSESSION			0x4259		/*   "BY"   */
 #define APPLEMIDI_COMMAND_SYNCHRONIZATION		0x434b		/*   "CK"   */
 #define APPLEMIDI_COMMAND_RECEIVER_FEEDBACK		0x5253		/*   "RS"   */
-
+#define APPLEMIDI_COMMAND_BITRATE_RECEIVE_LIMIT		0x524c		/*   "RL"   */
 
 static int	hf_applemidi_signature			= -1;
 static int	hf_applemidi_command			= -1;
@@ -76,6 +88,8 @@ static int	hf_applemidi_timestamp2			= -1;
 static int	hf_applemidi_timestamp3			= -1;
 static int	hf_applemidi_sequence_num		= -1;
 static int	hf_applemidi_rtp_sequence_num		= -1;
+static int	hf_applemidi_rtp_bitrate_limit		= -1;
+static int	hf_applemidi_unknown_data		= -1;
 
 
 static gint	ett_applemidi				= -1;
@@ -83,22 +97,33 @@ static gint	ett_applemidi_seq_num			= -1;
 
 
 static const value_string applemidi_commands[] = {
-	{ APPLEMIDI_COMMAND_INVITATION,				"Invitation" },
+	{ APPLEMIDI_COMMAND_INVITATION,			"Invitation" },
 	{ APPLEMIDI_COMMAND_INVITATION_REJECTED,	"Invitation Rejected" },
 	{ APLLEMIDI_COMMAND_INVITATION_ACCEPTED,	"Invitation Accepted" },
-	{ APPLEMIDI_COMMAND_ENDSESSION,				"End Session" },
+	{ APPLEMIDI_COMMAND_ENDSESSION,			"End Session" },
 	{ APPLEMIDI_COMMAND_SYNCHRONIZATION,		"Synchronization" },
 	{ APPLEMIDI_COMMAND_RECEIVER_FEEDBACK,		"Receiver Feedback" },
+	{ APPLEMIDI_COMMAND_BITRATE_RECEIVE_LIMIT,	"Bitrate Receive Limit" },
 	{ 0,						NULL },
 };
 
 
-static int			proto_applemidi			= -1;
+static int			proto_applemidi		= -1;
 
 static dissector_handle_t	applemidi_handle;
 static dissector_handle_t	rtp_handle;
 
+static const char applemidi_unknown_command[]		= "unknown command: 0x%04x";
+
+
+static void free_encoding_name_str (void *ptr)
+{
+  encoding_name_and_rate_t *encoding_name_and_rate = (encoding_name_and_rate_t *)ptr;
 
+  if (encoding_name_and_rate->encoding_name) {
+    g_free(encoding_name_and_rate->encoding_name);
+  }
+}
 
 static void
 dissect_applemidi_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint16 command ) {
@@ -106,7 +131,9 @@ dissect_applemidi_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, g
 	guint16		 seq_num;
 	guint8		 count;
 	guint8		*name;
-	unsigned int	 offset			= 0;
+	gint		 offset			= 0;
+	gint		 len;
+	gint		 string_size;
 	proto_tree	*applemidi_tree;
 	proto_tree	*applemidi_tree_seq_num;
 
@@ -116,17 +143,17 @@ dissect_applemidi_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, g
 	/* Clear out stuff in the info column */
 	col_clear( pinfo->cinfo, COL_INFO );
 
-	col_add_fstr( pinfo->cinfo, COL_INFO, "%s", val_to_str( command, applemidi_commands, "Unknown Command: 0x%04x" ) );
+	col_add_fstr( pinfo->cinfo, COL_INFO, "%s", val_to_str( command, applemidi_commands, applemidi_unknown_command ) );
 
 	if ( tree ) {
 		proto_item *ti;
-		ti = proto_tree_add_item( tree, proto_applemidi, tvb, 0, -1, ENC_NA );
+		ti = proto_tree_add_item( tree, proto_applemidi, tvb, 0, -1, ENC_NA  );
 		applemidi_tree = proto_item_add_subtree( ti, ett_applemidi );
 
-		proto_tree_add_item( applemidi_tree, hf_applemidi_signature, tvb, offset, 2, ENC_BIG_ENDIAN );
+		proto_tree_add_item( applemidi_tree, hf_applemidi_signature, tvb, offset, 2, ENC_BIG_ENDIAN  );
 		offset += 2;
 
-		proto_tree_add_item( applemidi_tree, hf_applemidi_command, tvb, offset, 2, ENC_BIG_ENDIAN );
+		proto_tree_add_item( applemidi_tree, hf_applemidi_command, tvb, offset, 2, ENC_BIG_ENDIAN  );
 		offset += 2;
 
 		/* the format of packets for "IN", "NO", "OK" and "BY" is identical and contains
@@ -134,15 +161,14 @@ dissect_applemidi_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, g
 		 * the SSRC that is used by the respective sides RTP-entity and optionally the
 		 * name of the participant */
 		if ( ( APPLEMIDI_COMMAND_INVITATION == command ) || ( APPLEMIDI_COMMAND_INVITATION_REJECTED == command ) || ( APLLEMIDI_COMMAND_INVITATION_ACCEPTED == command ) || ( APPLEMIDI_COMMAND_ENDSESSION == command ) ) {
-			int len;
 
-			proto_tree_add_item( applemidi_tree, hf_applemidi_protocol_version, tvb, offset, 4, ENC_BIG_ENDIAN );
+			proto_tree_add_item( applemidi_tree, hf_applemidi_protocol_version, tvb, offset, 4, ENC_BIG_ENDIAN  );
 			offset += 4;
 
-			proto_tree_add_item( applemidi_tree, hf_applemidi_token, tvb, offset, 4, ENC_BIG_ENDIAN );
+			proto_tree_add_item( applemidi_tree, hf_applemidi_token, tvb, offset, 4, ENC_BIG_ENDIAN  );
 			offset += 4;
 
-			proto_tree_add_item( applemidi_tree, hf_applemidi_ssrc, tvb, offset, 4, ENC_BIG_ENDIAN );
+			proto_tree_add_item( applemidi_tree, hf_applemidi_ssrc, tvb, offset, 4, ENC_BIG_ENDIAN  );
 			offset += 4;
 
 			len = tvb_reported_length(tvb) - offset;
@@ -150,8 +176,10 @@ dissect_applemidi_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, g
 			/* Name is optional */
 			if ( len > 0 ) {
 				name = tvb_get_ephemeral_string( tvb, offset, len );
-				proto_tree_add_item( applemidi_tree, hf_applemidi_name, tvb, offset, len, ENC_ASCII|ENC_NA );
+				string_size = (gint)( strlen( name ) + 1 );
+				proto_tree_add_item( applemidi_tree, hf_applemidi_name, tvb, offset, string_size, ENC_UTF_8|ENC_NA );
 				col_append_fstr( pinfo->cinfo, COL_INFO, ": peer = \"%s\"", name );
+				offset += string_size;
 			}
 
 		/* the synchronization packet contains three 64bit timestamps,  and a value to define how
@@ -168,7 +196,7 @@ dissect_applemidi_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, g
 			proto_tree_add_item( applemidi_tree, hf_applemidi_padding, tvb, offset, 3, ENC_BIG_ENDIAN );
 			offset += 3;
 
-			proto_tree_add_item(applemidi_tree, hf_applemidi_timestamp1, tvb, offset, 8, ENC_BIG_ENDIAN );
+			proto_tree_add_item( applemidi_tree, hf_applemidi_timestamp1, tvb, offset, 8, ENC_BIG_ENDIAN );
 			offset += 8;
 
 			proto_tree_add_item( applemidi_tree, hf_applemidi_timestamp2, tvb, offset, 8, ENC_BIG_ENDIAN );
@@ -193,12 +221,28 @@ dissect_applemidi_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, g
 			offset += 4;
 
 			col_append_fstr( pinfo->cinfo, COL_INFO, ": seq = %u", seq_num );
+		/* With the bitrate receive limit packet, the recipient can tell the sender to limit
+		   the transmission to a certain bitrate.  This is important if the peer is a gateway
+		   to a hardware-device that only supports a certain speed.  Like the MIDI 1.0 DIN-cable
+		   MIDI-implementation which is limited to 31250.  */
+		} else if ( APPLEMIDI_COMMAND_BITRATE_RECEIVE_LIMIT == command ) {
+			proto_tree_add_item( applemidi_tree, hf_applemidi_ssrc, tvb, offset, 4, ENC_BIG_ENDIAN );
+			offset += 4;
+
+			ti = proto_tree_add_item( applemidi_tree, hf_applemidi_rtp_bitrate_limit, tvb, offset, 4, ENC_BIG_ENDIAN );
+			offset += 4;
+		}
+		/* If there is any remaining data (possibly because an unknown command was encountered),
+		 * we just dump it here */
+		len = tvb_length_remaining( tvb, offset );
+		if ( len > 0 ) {
+			proto_tree_add_item( applemidi_tree, hf_applemidi_unknown_data, tvb, offset, len, ENC_NA );
 		}
 	}
 }
 
 static gboolean
-test_applemidi(tvbuff_t *tvb, guint16 *command_p) {
+test_applemidi(tvbuff_t *tvb, guint16 *command_p, gboolean conversation_established ) {
 
 	*command_p = 0xffff;
 
@@ -208,19 +252,29 @@ test_applemidi(tvbuff_t *tvb, guint16 *command_p) {
 
 	*command_p = tvb_get_ntohs( tvb, 2 );
 
-	/* ... followed by packet-command: "IN", "NO", "OK", "BY", "CK" and "RS" */
-	if ( ( APPLEMIDI_COMMAND_INVITATION          == *command_p ) ||
-	     ( APPLEMIDI_COMMAND_INVITATION_REJECTED == *command_p ) ||
-	     ( APLLEMIDI_COMMAND_INVITATION_ACCEPTED == *command_p ) ||
-	     ( APPLEMIDI_COMMAND_ENDSESSION          == *command_p ) ||
-	     ( APPLEMIDI_COMMAND_SYNCHRONIZATION     == *command_p ) ||
-	     ( APPLEMIDI_COMMAND_RECEIVER_FEEDBACK   == *command_p ) )
+	/* If the conversation is establised (one prior packet with a valid known command)
+	 * we won't check the commands anymore - this way we still show new commands
+	 * Apple might introduct as "unknown" instead of punting to RTP-dissector */
+	if ( conversation_established ) {
+		return TRUE;
+	}
+
+
+	/* ... followed by packet-command: "IN", "NO", "OK", "BY", "CK" and "RS" and "RL" */
+	if ( ( APPLEMIDI_COMMAND_INVITATION            == *command_p ) ||
+	     ( APPLEMIDI_COMMAND_INVITATION_REJECTED   == *command_p ) ||
+	     ( APLLEMIDI_COMMAND_INVITATION_ACCEPTED   == *command_p ) ||
+	     ( APPLEMIDI_COMMAND_ENDSESSION            == *command_p ) ||
+	     ( APPLEMIDI_COMMAND_SYNCHRONIZATION       == *command_p ) ||
+	     ( APPLEMIDI_COMMAND_RECEIVER_FEEDBACK     == *command_p ) ||
+	     ( APPLEMIDI_COMMAND_BITRATE_RECEIVE_LIMIT == *command_p ) )
 		return TRUE;
 
 	return FALSE;
 }
 
 
+
 /* dissect_applemidi() is called when a packet is seen from a previously identified applemidi conversation */
 /*  If the packet isn't a valid applemidi packet, assume it's an RTP-MIDI packet.                          */
 
@@ -228,7 +282,7 @@ static void
 dissect_applemidi( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) {
 	guint16		command;
 
-	if ( test_applemidi( tvb, &command ) )
+	if ( test_applemidi( tvb, &command, TRUE ) )
 		dissect_applemidi_common( tvb, pinfo, tree, command );
 	else
 		call_dissector( rtp_handle, tvb, pinfo, tree );
@@ -239,18 +293,39 @@ dissect_applemidi_heur( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) {
 
 	guint16		 command;
 	conversation_t	*p_conv;
+	struct _rtp_conversation_info *p_conv_data = NULL;
+	encoding_name_and_rate_t *encoding_name_and_rate = NULL;
+	GHashTable *rtp_dyn_payload = NULL;
+	gint *key;
 
 	if ( tvb_length( tvb ) < 4)
 		return FALSE;  /* not enough bytes to check */
 
-	if ( !test_applemidi( tvb, &command ) ) {
+	if ( !test_applemidi( tvb, &command, FALSE ) ) {
 		return FALSE;
 	}
 
-	/* call dissect_applemidi() from now on for UDP packets on this "connection" */
+	/* set dynamic payload-type 97 which is used by Apple for their RTP-MIDI implementation for this
+	   address/port-tuple to cause RTP-dissector to call the RTP-MIDI-dissector for payload-decoding */
+
+	encoding_name_and_rate = g_malloc( sizeof( encoding_name_and_rate_t ) );
+	rtp_dyn_payload = g_hash_table_new_full( g_int_hash, g_int_equal, g_free, free_encoding_name_str );
+	encoding_name_and_rate->encoding_name = g_strdup( "rtp-midi" );
+	encoding_name_and_rate->sample_rate = 10000;
+	key = g_malloc( sizeof( gint ) );
+	*key = 97;
+	g_hash_table_insert( rtp_dyn_payload, key, encoding_name_and_rate );
+        rtp_add_address( pinfo, &pinfo->src, pinfo->srcport, 0, APPLEMIDI_DISSECTOR_SHORTNAME, pinfo->fd->num, FALSE, rtp_dyn_payload);
+
+	/* call dissect_applemidi() from now on for UDP packets on this "connection"
+	   it is important to do this step after calling rtp_add_address, otherwise
+	   all further packets will go directly to the RTP-dissector!                */
+
 	p_conv = find_or_create_conversation(pinfo);
 	conversation_set_dissector( p_conv, applemidi_handle );
 
+	/* punt to actual decoding */
+
 	dissect_applemidi_common( tvb, pinfo, tree, command );
 	return TRUE;
 
@@ -417,6 +492,30 @@ proto_register_applemidi( void )
 				NULL, HFILL
 			}
 		},
+		{
+			&hf_applemidi_rtp_bitrate_limit,
+			{
+				"Bitrate limit",
+				"applemidi.bitrate_limit",
+				FT_UINT32,
+				BASE_DEC,
+				NULL,
+				0x0,
+				NULL, HFILL
+			}
+		},
+		{
+			&hf_applemidi_unknown_data,
+			{
+				"Unknown Data",
+				"rtpmidi.unknown_data",
+				FT_BYTES,
+				BASE_NONE,
+				NULL,
+				0x00,
+				NULL, HFILL
+			}
+		},
 	};