Set the length of the L2TP tvbuff based on the length in the L2TP

header, if present.

Don't explicitly base the length of the subset we hand to the PPP
dissector on the length in the header, as it might not be present;
instead, just use -1 for the lengths, as we set the length of our tvbuff
if there's a length in the L2TP header.

Set the length of the L2TP top-level protocol item for data packets, so
it covers the L2TP header but not the packet data.

Don't put a padding item into the tree if there's no padding.

svn path=/trunk/; revision=6922

1 files changed, 21 insertions, 13 deletions

diff --git a/packet-l2tp.c b/packet-l2tp.c
index aec2dea246..19fa62738d 100644
--- a/packet-l2tp.c
+++ b/packet-l2tp.c
@@ -7,7 +7,7 @@
  * Laurent Cazalet <laurent.cazalet@mailclub.net>
  * Thomas Parvais <thomas.parvais@advalvas.be>
  *
- * $Id: packet-l2tp.c,v 1.36 2002/12/11 19:59:08 guy Exp $
+ * $Id: packet-l2tp.c,v 1.37 2003/01/14 18:57:07 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -308,11 +308,10 @@ static void
 dissect_l2tp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 {
   proto_tree *l2tp_tree=NULL, *l2tp_avp_tree, *l2tp_lcp_avp_tree, *ctrl_tree;
-  proto_item *ti, *tf, *te;
+  proto_item *l2tp_item = NULL, *ti, *tf, *te;
   int rhcode;
   int index = 0;
   int tmp_index;
-  int proto_length = 0;
   guint16 length = 0;		/* Length field */
   guint16 tid;			/* Tunnel ID */
   guint16 cid;			/* Call ID */
@@ -405,15 +404,20 @@ dissect_l2tp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   }
 
   if (LENGTH_BIT(control)) {
-	proto_length = length;
-  }
-  else {
-	proto_length = tvb_length(tvb);
+	/*
+	 * Set the length of this tvbuff to be no longer than the length
+	 * in the header.
+	 *
+	 * XXX - complain if that length is longer than the length of
+	 * the tvbuff?  Have "set_actual_length()" return a Boolean
+	 * and have its callers check the result?
+	 */
+	set_actual_length(tvb, length);
   }
 
   if (tree) {
-        ti = proto_tree_add_item(tree,proto_l2tp, tvb, 0, proto_length, FALSE);
-	l2tp_tree = proto_item_add_subtree(ti, ett_l2tp);
+        l2tp_item = proto_tree_add_item(tree,proto_l2tp, tvb, 0, -1, FALSE);
+	l2tp_tree = proto_item_add_subtree(l2tp_item, ett_l2tp);
 
 	ti = proto_tree_add_text(l2tp_tree, tvb, 0, 2,
 			"Packet Type: %s Tunnel Id=%d Session Id=%d",
@@ -461,19 +465,23 @@ dissect_l2tp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 		    offset_size);
 	}
 	index += 2;
-	if (tree) {
-		proto_tree_add_text(l2tp_tree, tvb, index, offset_size, "Offset Padding");
+	if (offset_size != 0) {
+		if (tree) {
+			proto_tree_add_text(l2tp_tree, tvb, index, offset_size, "Offset Padding");
+		}
+		index += offset_size;
 	}
-	index += offset_size;
   }
   if (tree && (LENGTH_BIT(control))&&(length==12)) {
             proto_tree_add_text(l2tp_tree, tvb, 0, 0, "Zero Length Bit message");
   }
 
   if (!CONTROL_BIT(control)) {  /* Data Messages so we are done */
+	if (tree)
+		proto_item_set_len(l2tp_item, index);
 	/* If we have data, signified by having a length bit, dissect it */
 	if (tvb_offset_exists(tvb, index)) {
-		next_tvb = tvb_new_subset(tvb, index, -1, proto_length - index);
+		next_tvb = tvb_new_subset(tvb, index, -1, -1);
 		call_dissector(ppp_hdlc_handle, next_tvb, pinfo, tree);
 	}
 	return;