Show the Vines Fragmentation Protocol control flags field as bitflags,

rather than as a single field.  If bits other than the two defined bits
are set in the first byte of the packet, don't dissect UDP packets as
Vines FRP, so that other dissectors get a chance to look at the packet.

svn path=/trunk/; revision=46732

1 files changed, 66 insertions, 37 deletions

diff --git a/epan/dissectors/packet-vines.c b/epan/dissectors/packet-vines.c
index 35dd831f44..4e2123cbe5 100644
--- a/epan/dissectors/packet-vines.c
+++ b/epan/dissectors/packet-vines.c
@@ -98,8 +98,13 @@
 #define UDP_PORT_VINES	573
 
 static int proto_vines_frp = -1;
+static int hf_vines_frp_flags = -1;
+static int hf_vines_frp_flags_first_fragment = -1;
+static int hf_vines_frp_flags_last_fragment = -1;
+static int hf_vines_frp_sequence_number = -1;
 
 static gint ett_vines_frp = -1;
+static gint ett_vines_frp_flags = -1;
 
 static int proto_vines_llc = -1;
 
@@ -243,6 +248,10 @@ capture_vines(packet_counts *ld)
 static dissector_handle_t vines_ip_handle;
 static dissector_handle_t data_handle;
 
+/* Control flags */
+#define VINES_FRP_FIRST_FRAGMENT	0x01
+#define VINES_FRP_LAST_FRAGMENT		0x02
+
 /* AFAIK Vines FRP (Fragmentation Protocol) is used on all media except
  * Ethernet and TR (and probably FDDI) - Fragmentation on these media types
  * is not possible
@@ -254,7 +263,7 @@ dissect_vines_frp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 	guint8   vines_frp_ctrl;
 	proto_tree *vines_frp_tree;
 	proto_item *ti;
-	gchar	*frp_flags_str="";
+	proto_tree *flags_tree;
 	tvbuff_t *next_tvb;
 
 	col_set_str(pinfo->cinfo, COL_PROTOCOL, "Vines FRP");
@@ -267,41 +276,16 @@ dissect_vines_frp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 
 		vines_frp_ctrl = tvb_get_guint8(tvb, 0);
 
-		/*
-		 * 1: first fragment of vines packet
-		 * 2: last fragment of vines packet
-		 * 4 ... 80: unused
-		 */
-		switch (vines_frp_ctrl) {
-
-		case 0:
-			frp_flags_str= "middle";
-			break;
-
-		case 1:
-			frp_flags_str= "first";
-			break;
-
-		case 2:
-			frp_flags_str= "last";
-			break;
-
-		case 3:
-			frp_flags_str= "only";
-			break;
+		ti = proto_tree_add_uint(vines_frp_tree, hf_vines_frp_flags,
+		    tvb, 0, 1, vines_frp_ctrl);
+		flags_tree = proto_item_add_subtree(ti, ett_vines_frp_flags);
+		proto_tree_add_boolean(flags_tree, hf_vines_frp_flags_first_fragment,
+		    tvb, 0, 1, vines_frp_ctrl);
+		proto_tree_add_boolean(flags_tree, hf_vines_frp_flags_last_fragment,
+		    tvb, 0, 1, vines_frp_ctrl);
 
-		default:
-			frp_flags_str= "please report: unknown";
-			break;
-		}
-
-		proto_tree_add_text(vines_frp_tree, tvb, 0, 1,
-				    "Control Flags: 0x%02x = %s fragment",
-				    vines_frp_ctrl, frp_flags_str);
-
-		proto_tree_add_text(vines_frp_tree, tvb, 1, 1,
-				    "Sequence Number: 0x%02x",
-				    tvb_get_guint8(tvb, 1));
+		proto_tree_add_item(vines_frp_tree, hf_vines_frp_sequence_number,
+		    tvb, 1, 1, ENC_LITTLE_ENDIAN);
 	}
 
 	/* Decode the "real" Vines now */
@@ -309,22 +293,65 @@ dissect_vines_frp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 	call_dissector(vines_ip_handle, next_tvb, pinfo, tree);
 }
 
+static int
+dissect_vines_frp_new(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
+    void *params _U_)
+{
+	guint8   vines_frp_ctrl;
+
+	if (!tvb_bytes_exist(tvb, 0, 1)) {
+		/* Too short to check the flags value. */
+		return 0;
+	}
+	vines_frp_ctrl = tvb_get_guint8(tvb, 0);
+	if ((vines_frp_ctrl & ~(VINES_FRP_FIRST_FRAGMENT|VINES_FRP_LAST_FRAGMENT)) != 0) {
+		/* Those are the only flags; if anything else is set, this
+		 * is presumably not Vines FRP. */
+		return 0;
+	}
+	dissect_vines_frp(tvb, pinfo, tree);
+	return tvb_length(tvb);
+}
+
 void
 proto_register_vines_frp(void)
 {
+	static hf_register_info hf[] = {
+	  { &hf_vines_frp_flags,
+	    { "Control Flags",		"vines_frp.flags",
+	      FT_UINT8,		BASE_HEX,	NULL,	0x0,
+	      NULL, HFILL }},
+
+	  { &hf_vines_frp_flags_first_fragment,
+	    { "First fragment",		"vines_frp.flags.first_fragment",
+	      FT_BOOLEAN,	8,	NULL,	VINES_FRP_FIRST_FRAGMENT,
+	      NULL, HFILL }},
+
+	  { &hf_vines_frp_flags_last_fragment,
+	    { "Last fragment",		"vines_frp.flags.last_fragment",
+	      FT_BOOLEAN,	8,	NULL,	VINES_FRP_LAST_FRAGMENT,
+	      NULL, HFILL }},
+
+	  { &hf_vines_frp_sequence_number,
+	    { "Sequence Number",	"vines_frp.sequence_number",
+	      FT_UINT8,		BASE_HEX,	NULL,	0x0,
+	      NULL, HFILL }},
+	};
 	static gint *ett[] = {
 		&ett_vines_frp,
+		&ett_vines_frp_flags
 	};
 
 	proto_vines_frp = proto_register_protocol(
 	    "Banyan Vines Fragmentation Protocol", "Vines FRP", "vines_frp");
+	proto_register_field_array(proto_vines_ip, hf, array_length(hf));
 	proto_register_subtree_array(ett, array_length(ett));
 }
 
 void
 proto_reg_handoff_vines_frp(void)
 {
-	dissector_handle_t vines_frp_handle;
+	dissector_handle_t vines_frp_handle, vines_frp_new_handle;
 
 	vines_frp_handle = create_dissector_handle(dissect_vines_frp,
 	    proto_vines_frp);
@@ -332,7 +359,9 @@ proto_reg_handoff_vines_frp(void)
 
 	/* XXX: AFAIK, src and dst port must be the same; should
 	   the dissector check for that? */
-	dissector_add_uint("udp.port", UDP_PORT_VINES, vines_frp_handle);
+	vines_frp_new_handle = new_create_dissector_handle(dissect_vines_frp_new,
+	    proto_vines_frp);
+	dissector_add_uint("udp.port", UDP_PORT_VINES, vines_frp_new_handle);
 }
 
 static dissector_table_t vines_llc_dissector_table;