There's no need for two separate "Extension Length" fields - you can

add a 1-byte item for a FT_UINT16 field.

Don't create a separate tvbuff for the extensions, just use the tvbuff
handed to us and start dissecting at the beginning of the extensions.

Use the reported length, not the captured length, to indicate how much
to dissect, so that if the frame was cut short by the snapshot length,
we throw a "Short Frame" exception.

Use "proto_tree_add_item()", not "proto_tree_add_bytes()", to add an
item for the data in an unknown extension.

svn path=/trunk/; revision=4488

1 files changed, 11 insertions, 35 deletions

diff --git a/packet-mip.c b/packet-mip.c
index 505061407c..1c9d9b1cc3 100644
--- a/packet-mip.c
+++ b/packet-mip.c
@@ -2,7 +2,7 @@
  * Routines for Mobile IP dissection
  * Copyright 2000, Stefan Raab <sraab@cisco.com>
  *
- * $Id: packet-mip.c,v 1.24 2001/12/10 00:25:30 guy Exp $
+ * $Id: packet-mip.c,v 1.25 2002/01/05 22:09:17 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -68,7 +68,6 @@ static int hf_mip_ident = -1;
 static int hf_mip_ext_type = -1;
 static int hf_mip_ext_stype = -1;
 static int hf_mip_ext_len = -1;
-static int hf_mip_ext_len2 = -1;
 static int hf_mip_ext = -1;
 static int hf_mip_aext_spi = -1;
 static int hf_mip_aext_auth = -1;
@@ -167,7 +166,8 @@ static const value_string mip_ext_stypes[]= {
 };
 /* Code to dissect extensions */
 static void
-dissect_mip_extensions( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+dissect_mip_extensions( tvbuff_t *tvb, int offset, packet_info *pinfo,
+			proto_tree *tree)
 {
   proto_item   *ti;
   proto_tree   *exts_tree=NULL;
@@ -175,9 +175,6 @@ dissect_mip_extensions( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   size_t        ext_len;
   guint8        ext_type;
   guint8        ext_subtype=0;
-  size_t        offset = 0;
-  gchar         ext_data[256];
-  size_t        dataLength;
   size_t        hdrLen;
 
   /* None of this really matters if we don't have a tree */
@@ -185,12 +182,11 @@ dissect_mip_extensions( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 
   /* Add our tree, if we have extensions */
   ti = proto_tree_add_text(tree, tvb, offset,
-		tvb_length(tvb)-offset, "Extensions");
+		tvb_length_remaining(tvb, offset), "Extensions");
   exts_tree = proto_item_add_subtree(ti, ett_mip_exts);
 
-  /* And, handle each extensions */
-  dataLength = tvb_length(tvb);
-  while (offset < dataLength) {
+  /* And, handle each extension */
+  while (tvb_reported_length_remaining(tvb, offset) > 0) {
 
 	/* Get our extension info */
 	ext_type = tvb_get_guint8(tvb, offset);
@@ -207,14 +203,6 @@ dissect_mip_extensions( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 	  hdrLen = 2;
 	}
 	
-	/* If everything seems valid, make a tree for it, and update length */
-	if ((offset + ext_len + hdrLen) > dataLength) {
-	  /* Ut-Oh . . . we're done after this one */
-	  g_warning("Invalid MIP extension.  Length (%d) greater than remaining data (%d)",
-				ext_len, (dataLength - (offset + hdrLen)));
-	  ext_len = dataLength - (offset + hdrLen); /* Fudge it */
-	}
-
 	ti = proto_tree_add_text(exts_tree, tvb, offset, ext_len + hdrLen,
 				 "Extension: %s",
 				 val_to_str(ext_type, mip_ext_types,
@@ -250,7 +238,7 @@ dissect_mip_extensions( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 	   */
 	  proto_tree_add_uint(ext_tree, hf_mip_ext_stype, tvb, offset, 1, ext_subtype);
 	  offset++;
-	  proto_tree_add_uint(ext_tree, hf_mip_ext_len2, tvb, offset, 2, ext_len);
+	  proto_tree_add_uint(ext_tree, hf_mip_ext_len, tvb, offset, 2, ext_len);
 	  offset+=2;
 	  /* SPI */
 	  proto_tree_add_item(ext_tree, hf_mip_aext_spi, tvb, offset, 4, FALSE);
@@ -266,10 +254,8 @@ dissect_mip_extensions( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 	case MF_CHALLENGE_EXT:  /* RFC 3012 */
 	  /* The default dissector is good here.  The challenge is all hex anyway. */
 	default:
-	  tvb_memcpy(tvb, (guint8*)ext_data, offset, MIN(ext_len,
-		     (dataLength - (offset + 2))));
-	  proto_tree_add_bytes(ext_tree, hf_mip_ext, tvb, offset, ext_len,
-						   ext_data);
+	  proto_tree_add_item(ext_tree, hf_mip_ext, tvb, offset, ext_len, FALSE);
+	  break;
 	} /* ext type */
 
 	offset += ext_len;
@@ -395,13 +381,8 @@ dissect_mip( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   } /* End switch */
 
   if (tree) {
-	dataRemaining = tvb_length(tvb) - offset;
-	if (dataRemaining > 0) {
-	  extensions_tvb = tvb_new_subset(tvb, offset, dataRemaining,
-									  dataRemaining);
-	  
-	  dissect_mip_extensions(extensions_tvb, pinfo, mip_tree);
-	}
+	if (tvb_offset_exists(tvb, offset))
+	  dissect_mip_extensions(tvb, offset, pinfo, mip_tree);
   }
 } /* dissect_mip */
 
@@ -500,11 +481,6 @@ void proto_register_mip(void)
 	  },
 	  { &hf_mip_ext_len,
 		 { "Extension Length",         "mip.ext.len",
-			FT_UINT8, BASE_DEC, NULL, 0,
-			"Mobile IP Extension Length.", HFILL }
-	  },
-	  { &hf_mip_ext_len2,
-		 { "Extension Length",         "mip.ext.len2",
 			FT_UINT16, BASE_DEC, NULL, 0,
 			"Mobile IP Extension Length.", HFILL }
 	  },