Have a flag in the "packet_info" structure, which indicates whether the

stuff currently being dissected is part of a packet included in an error
packet (e.g., an ICMP Unreachable packet).  Have the TCP dissector not
bother doing reassembly if the TCP segment is part of an error packet,
rather than an actual TCP transmission; other dissectors might want to
treat those packets specially as well.

Add to the "tcpinfo" structure a flag indicating whether the URG flag
was set, rather than having the zero or non-zero value of the urgent
pointer indicate that.  (Yes, at least as I read RFC 793, a zero urgent
pointer value isn't useful, as it means "the stuff before this segment
is urgent", but it's certainly possible to put onto the wire a TCP
segment with URG set and a zero urgent pointer.)

Don't dissect the TCP header by grabbing the entire header with
"tvb_memcpy()" and then pulling stuff out of it - extract stuff with
individual tvbuff calls, and put stuff into the protocol tree and the
Info column as we extract it, so that we can dissect a partial header.
This lets us, for example, get the source and destination ports from the
TCP header of the part of a TCP segment included in a minimum-length
ICMPv4 error packet.

svn path=/trunk/; revision=3986

1 files changed, 16 insertions, 2 deletions

diff --git a/packet-icmpv6.c b/packet-icmpv6.c
index dc5ee6acc1..23e736705d 100644
--- a/packet-icmpv6.c
+++ b/packet-icmpv6.c
@@ -1,7 +1,7 @@
 /* packet-icmpv6.c
  * Routines for ICMPv6 packet disassembly
  *
- * $Id: packet-icmpv6.c,v 1.52 2001/09/27 10:35:40 guy Exp $
+ * $Id: packet-icmpv6.c,v 1.53 2001/10/01 08:29:34 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -116,6 +116,7 @@ dissect_contained_icmpv6(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tr
     address save_net_dst;
     address save_src;
     address save_dst;
+    gboolean save_in_error_pkt;
 
     next_tvb = tvb_new_subset(tvb, offset, -1, -1);
 
@@ -139,10 +140,20 @@ dissect_contained_icmpv6(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tr
 	save_src = pinfo->src;
 	save_dst = pinfo->dst;
 
+	/* Save the current value of the "we're inside an error packet"
+	   flag, and set that flag; subdissectors may treat packets
+	   that are the payload of error packets differently from
+	   "real" packets. */
+	save_in_error_pkt = pinfo->in_error_pkt;
+	pinfo->in_error_pkt = TRUE;
+
 	/* Dissect the contained packet.
 	   Catch ReportedBoundsError, and do nothing if we see it,
 	   because it's not an error if the contained packet is short;
-	   there's no guarantee that all of it was included. */
+	   there's no guarantee that all of it was included.
+
+	   XXX - should catch BoundsError, and re-throw it after cleaning
+	   up. */
 	TRY {
 	    call_dissector(ipv6_handle, next_tvb, pinfo, tree);
 	}
@@ -151,6 +162,9 @@ dissect_contained_icmpv6(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tr
 	}
 	ENDTRY;
 
+	/* Restore the "we're inside an error packet" flag. */
+	pinfo->in_error_pkt = save_in_error_pkt;
+
 	/* Restore the addresses. */
 	pinfo->dl_src = save_dl_src;
 	pinfo->dl_dst = save_dl_dst;