Catch the ReportedBoundsError exception in the DNS and TPKT dissectors

when dissecting messages over TCP, so that an error in one message
doesn't stop us from dissecting the next message in the segment, if any.

Put an XXX comment before the code that constructs the tvbuff for each
message inside a TCP segment, noting that we really want tvbuffs to have
three lengths and to have a new type of exception thrown if you go past
the second length but not past the reported length.

svn path=/trunk/; revision=4782

1 files changed, 33 insertions, 2 deletions

diff --git a/packet-dns.c b/packet-dns.c
index 6b8ec359f0..d123829315 100644
--- a/packet-dns.c
+++ b/packet-dns.c
@@ -1,7 +1,7 @@
 /* packet-dns.c
  * Routines for DNS packet disassembly
  *
- * $Id: packet-dns.c,v 1.81 2002/02/22 08:45:02 guy Exp $
+ * $Id: packet-dns.c,v 1.82 2002/02/22 11:28:03 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -39,6 +39,7 @@
 #include "ipproto.h"
 #include <epan/resolv.h>
 #include "packet-dns.h"
+#include "packet-frame.h"
 #include "prefs.h"
 
 static int proto_dns = -1;
@@ -2012,6 +2013,18 @@ dissect_dns_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 		 * Construct a tvbuff containing the amount of the payload
 		 * we have available.  Make its reported length the
 		 * amount of data in the DNS-over-TCP packet.
+		 *
+		 * XXX - if reassembly isn't enabled. the subdissector
+		 * will throw a BoundsError exception, rather than a
+		 * ReportedBoundsError exception.  We really want
+		 * a tvbuff where the length is "length", the reported
+		 * length is "plen + 2", and the "if the snapshot length
+		 * were infinite" length were the minimum of the
+		 * reported length of the tvbuff handed to us and "plen+2",
+		 * with a new type of exception thrown if the offset is
+		 * within the reported length but beyond that third length,
+		 * with that exception getting the "Unreassembled Packet"
+		 * error.
 		 */
 		length = length_remaining;
 		if (length > plen + 2)
@@ -2020,8 +2033,26 @@ dissect_dns_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 
 		/*
 		 * Dissect the DNS-over-TCP packet.
+		 *
+		 * Catch the ReportedBoundsError exception; if this
+		 * particular message happens to get a ReportedBoundsError
+		 * exception, that doesn't mean that we should stop
+		 * dissecting COPS messages within this frame or chunk
+		 * of reassembled data.
+		 *
+		 * If it gets a BoundsError, we can stop, as there's nothing
+		 * more to see, so we just re-throw it.
 		 */
-		dissect_dns_common(next_tvb, plen, pinfo, tree, TRUE);
+		TRY {
+			dissect_dns_common(next_tvb, plen, pinfo, tree, TRUE);
+		}
+		CATCH(BoundsError) {
+			RETHROW;
+		}
+		CATCH(ReportedBoundsError) {
+			show_reported_bounds_error(tvb, pinfo, tree);
+		}
+		ENDTRY;
 
 		/*
 		 * Skip the DNS-over-TCP header and the payload.