Handle the case of multiple LDP PDUs per TCP segment. (Still needs to

handle the case of more than one TCP segment per LDP PDU....)

Fix the handling of some of the length fields.

svn path=/trunk/; revision=4276

1 files changed, 87 insertions, 31 deletions

diff --git a/packet-ldp.c b/packet-ldp.c
index 18bc99e4ae..87070889d4 100644
--- a/packet-ldp.c
+++ b/packet-ldp.c
@@ -1,7 +1,7 @@
 /* packet-ldp.c
  * Routines for ldp packet disassembly
  *
- * $Id: packet-ldp.c,v 1.19 2001/07/21 10:27:12 guy Exp $
+ * $Id: packet-ldp.c,v 1.20 2001/11/27 04:59:01 guy Exp $
  * 
  * Copyright (c) November 2000 by Richard Sharpe <rsharpe@ns.aus.com>
  *
@@ -546,55 +546,73 @@ dissect_ldp_label_abort_request(tvbuff_t *tvb, guint offset, packet_info *pinfo,
 
 }
 
-static void
-dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+static int
+dissect_ldp_pdu(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree)
 {
-  proto_tree     *ldp_tree = NULL, 
-                 *ti = NULL,
-                 *hdr_tree = NULL, *ldpid_tree = NULL;
-  int	         offset = 0, msg_cnt = 0;
+  proto_tree     *ldp_tree = NULL, *hdr_tree = NULL, *ldpid_tree = NULL;
+  proto_item     *ldp_item = NULL, *hdr_item = NULL, *ldpid_item = NULL;
+  int	         msg_cnt = 0;
   guint16        ldp_message = 0;
+  guint          pdu_len;
 
-  if (check_col(pinfo->fd, COL_PROTOCOL))
-    col_add_str(pinfo->fd, COL_PROTOCOL, "LDP");
   if (check_col(pinfo->fd, COL_INFO))
     col_clear(pinfo->fd, COL_INFO);
 
   if (tree) {  /* Build the tree info ..., this is wrong! FIXME */
 
-    ti = proto_tree_add_item(tree, proto_ldp, tvb, offset,
-			     tvb_length_remaining(tvb, offset), FALSE);
-    ldp_tree = proto_item_add_subtree(ti, ett_ldp);
+    ldp_item = proto_tree_add_item(tree, proto_ldp, tvb, offset,
+				   tvb_length_remaining(tvb, offset), FALSE);
+    ldp_tree = proto_item_add_subtree(ldp_item, ett_ldp);
 
-    ti = proto_tree_add_text(ldp_tree, tvb, 0, 10, "Header");
+  }
+
+  /* Dissect LDP Header */
 
-    hdr_tree = proto_item_add_subtree(ti, ett_ldp_header);
+  hdr_item = proto_tree_add_text(ldp_tree, tvb, offset, 10, "Header");
 
-    proto_tree_add_item(hdr_tree, hf_ldp_version, tvb, offset, 2, FALSE);
+  hdr_tree = proto_item_add_subtree(hdr_item, ett_ldp_header);
 
-    offset += 2;
+  proto_tree_add_item(hdr_tree, hf_ldp_version, tvb, offset, 2, FALSE);
 
-    proto_tree_add_item(hdr_tree, hf_ldp_pdu_len, tvb, offset, 2, FALSE);
+  offset += 2;
 
-    offset += 2;
+  proto_tree_add_item(hdr_tree, hf_ldp_pdu_len, tvb, offset, 2, FALSE);
+  pdu_len = tvb_get_ntohs(tvb, offset);
+  proto_item_set_len(ldp_item, pdu_len + 2);
 
-    ti = proto_tree_add_text(hdr_tree, tvb, offset, 6, "LDP Identifier");
+  /*
+   * XXX - do TCP reassembly, to handle LDP PDUs that cross TCP segment
+   * boundaries.
+   */
 
-    ldpid_tree = proto_item_add_subtree(ti, ett_ldp_ldpid);
+  offset += 2;
 
-    proto_tree_add_item(ldpid_tree, hf_ldp_lsr, tvb, offset, 4, FALSE);
+  if (pdu_len < 6) {
+    /*
+     * PDU is too short to hold the LDP identifier.
+     */
+    proto_tree_add_text(hdr_tree, tvb, offset, pdu_len,
+        "PDU too short (%u bytes, should be at least 6) for LDP Identifier",
+        pdu_len);
+    offset += pdu_len;
+    return offset;
+  }
 
-    offset += 4;
+  ldpid_item = proto_tree_add_text(hdr_tree, tvb, offset, 6, "LDP Identifier");
 
-    proto_tree_add_item(ldpid_tree, hf_ldp_ls_id, tvb, offset, 2, FALSE);
+  ldpid_tree = proto_item_add_subtree(ldpid_item, ett_ldp_ldpid);
 
-    offset += 2;
+  proto_tree_add_item(ldpid_tree, hf_ldp_lsr, tvb, offset, 4, FALSE);
 
-  }
+  offset += 4;
+  pdu_len -= 4;
 
-  offset = 10;
+  proto_tree_add_item(ldpid_tree, hf_ldp_ls_id, tvb, offset, 2, FALSE);
 
-  while (tvb_length_remaining(tvb, offset) > 0) { /* Dissect a message */
+  offset += 2;
+  pdu_len -= 2;
+
+  while (pdu_len > 0) { /* Dissect LDP TLV */
 
     guint msg_len;
 
@@ -610,7 +628,7 @@ dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
       else
 	col_add_fstr(pinfo->fd, COL_INFO, "%s", 
 		     val_to_str(ldp_message, ldp_message_types, "Unknown Message (0x%04X)"));
-
+	
     }
 
     msg_cnt++;
@@ -625,13 +643,25 @@ dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 			       val_to_str(ldp_message, ldp_message_types, "Unknown Message (0x%04X)"));
 
       msg_tree = proto_item_add_subtree(ti, ett_ldp_message);
-
+	
       proto_tree_add_item(msg_tree, hf_ldp_msg_type, tvb, offset, 2, FALSE);
 
       proto_tree_add_item(msg_tree, hf_ldp_msg_len, tvb, offset + 2, 2, FALSE);
 
+      if (msg_len < 4) {
+	proto_tree_add_text(msg_tree, tvb, offset + 4, msg_len,
+	    "Message too short (%u bytes, should be at least 4) for Message ID",
+	    msg_len);
+	goto next;
+      }
+
       proto_tree_add_item(msg_tree, hf_ldp_msg_id, tvb, offset + 4, 4, FALSE);
 
+      if (msg_len == 4) {
+      	/* Nothing past the message ID */
+      	goto next;
+      }
+
       switch (ldp_message) {
 
       case LDP_NOTIFICATION:
@@ -655,7 +685,7 @@ dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
       case LDP_KEEPALIVE:
 
 	dissect_ldp_keepalive(tvb, offset + 8, pinfo, msg_tree, msg_len - 4);
-
+	  
 	break;
 
       case LDP_ADDRESS:
@@ -703,6 +733,8 @@ dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
       default:
 
 	/* Some sort of unknown message, treat as undissected data */
+	proto_tree_add_text(msg_tree, tvb, offset + 8, msg_len - 4,
+			    "Message data"); 
 
 	break;
 
@@ -710,9 +742,33 @@ dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
     
     }
 
+next:
     offset += msg_len + 4;
+    pdu_len -= msg_len + 4;
 
   }
+  return offset;
+}
+
+static void
+dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+  if (check_col(pinfo->fd, COL_PROTOCOL))
+    col_add_str(pinfo->fd, COL_PROTOCOL, "LDP");
+
+  dissect_ldp_pdu(tvb, 0, pinfo, tree);
+}
+
+static void
+dissect_ldp_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+  int	         offset = 0;
+
+  if (check_col(pinfo->fd, COL_PROTOCOL))
+    col_add_str(pinfo->fd, COL_PROTOCOL, "LDP");
+
+  while (tvb_reported_length_remaining(tvb, offset) > 0) /* Dissect LDP PDUs */
+    offset = dissect_ldp_pdu(tvb, offset, pinfo, tree);
 }
 
 /* Register all the bits needed with the filtering engine */
@@ -845,7 +901,7 @@ proto_reg_handoff_ldp(void)
   tcp_port = global_ldp_tcp_port;
   udp_port = global_ldp_udp_port;
 
-  dissector_add("tcp.port", global_ldp_tcp_port, dissect_ldp, proto_ldp);
+  dissector_add("tcp.port", global_ldp_tcp_port, dissect_ldp_tcp, proto_ldp);
   dissector_add("udp.port", global_ldp_udp_port, dissect_ldp, proto_ldp);
 
 }