Re: [Ethereal-dev] packets not desegmented if not on the default port..

[didier <dgautheron@xxxxxxxx>]

Guy Harris wrote:

> Gigabit Ethernet interfaces (or even interfaces capable of gigabit
> speeds, even if they're not running at gigabit speeds) might do TCP
> checksum offloading, and some non-gigabit interfaces might do so as
> well; if so, then outgoing TCP segments delivered to the packet capture
> mechanism might not yet have had their checksum computed, and thus might
> have bad TCP checksums.
Don't know if it's useful or the right way to do it but what about :
Index: packet-frame.c
===================================================================
RCS file: /cvsroot/ethereal/packet-frame.c,v
retrieving revision 1.34
diff -u -r1.34 packet-frame.c
--- packet-frame.c	31 Jan 2003 01:02:03 -0000	1.34
+++ packet-frame.c	12 Feb 2003 22:06:50 -0000
@@ -213,8 +213,8 @@
 		 * but it wasn't in the fragment we dissected.
 		 */
 		if (check_col(pinfo->cinfo, COL_INFO))
-			col_append_str(pinfo->cinfo, COL_INFO,
-			    "[Unreassembled Packet]");
+			col_append_fstr(pinfo->cinfo, COL_INFO,
+			    "[Unreassembled Packet%s]", pinfo->current_error?pinfo->current_error:"");
 		proto_tree_add_protocol_format(tree, proto_unreassembled,
 		    tvb, 0, 0, "[Unreassembled Packet: %s]",
 		    pinfo->current_proto);
Index: packet-tcp.c
===================================================================
RCS file: /cvsroot/ethereal/packet-tcp.c,v
retrieving revision 1.171
diff -u -r1.171 packet-tcp.c
--- packet-tcp.c	28 Jan 2003 23:56:40 -0000	1.171
+++ packet-tcp.c	12 Feb 2003 22:06:52 -0000
@@ -1961,7 +1961,7 @@
    * Assume, initially, that we can't desegment.
    */
   pinfo->can_desegment = 0;
-
+  pinfo->current_error = "";
   th_sum = tvb_get_ntohs(tvb, offset + 16);
   if (!pinfo->fragmented && len >= reported_len) {
     /* The packet isn't part of an un-reassembled fragmented datagram
@@ -2016,6 +2016,7 @@
 
         /* Checksum is invalid, so we're not willing to desegment it. */
         desegment_ok = FALSE;
+        pinfo->current_error = ", TCP bad checksum";
       }
     } else {
       proto_tree_add_uint_format(tcp_tree, hf_tcp_checksum, tvb,
Index: epan/packet_info.h
===================================================================
RCS file: /cvsroot/ethereal/epan/packet_info.h,v
retrieving revision 1.29
diff -u -r1.29 packet_info.h
--- epan/packet_info.h	22 Jan 2003 06:26:36 -0000	1.29
+++ epan/packet_info.h	12 Feb 2003 22:06:52 -0000
@@ -116,6 +116,7 @@
 
 typedef struct _packet_info {
   const char *current_proto;	/* name of protocol currently being dissected */
+  char *current_error;          /* last decoding error */
   column_info *cinfo;		/* Column formatting information */
   frame_data *fd;
   union wtap_pseudo_header *pseudo_header;