Pull a lot of common code for handling 802.3 frames (i.e., frames with a

length field rather than an Ethernet type field) into a
"dissect_802_3()" routine.

In that routine, catch exceptions thrown by the IPX or LLC dissector or
dissectors under them, so that the trailer information is added to the
tree even if an exception is thrown (similar to what "ethertype()"
does).

svn path=/trunk/; revision=3002

1 files changed, 134 insertions, 0 deletions

diff --git a/packet-ieee8023.c b/packet-ieee8023.c
new file mode 100644
index 0000000000..2a671860c4
--- /dev/null
+++ b/packet-ieee8023.c
@@ -0,0 +1,134 @@
+/* packet-ieee8023.c
+ * Routine for dissecting 802.3 (as opposed to D/I/X Ethernet) packets.
+ *
+ * $Id: packet-ieee8023.c,v 1.1 2001/02/08 07:08:05 guy Exp $
+ *
+ * Ethereal - Network traffic analyzer
+ * By Gerald Combs <gerald@zing.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#ifdef HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+
+#include <glib.h>
+#include "packet.h"
+#include "packet-ieee8023.h"
+
+static dissector_handle_t ipx_handle;
+static dissector_handle_t llc_handle;
+
+static void add_trailer(proto_tree *fh_tree, int trailer_id,
+    tvbuff_t *trailer_tvb);
+
+void
+dissect_802_3(int length, gboolean is_802_2, tvbuff_t *tvb,
+	      int offset_after_length, packet_info *pinfo, proto_tree *tree,
+	      proto_tree *fh_tree, int length_id, int trailer_id)
+{
+  tvbuff_t		*volatile next_tvb;
+  tvbuff_t		*volatile trailer_tvb;
+
+  if (fh_tree)
+    proto_tree_add_uint(fh_tree, length_id, tvb, offset_after_length - 2, 2,
+			length);
+
+  /* Give the next dissector only 'length' number of bytes */
+  TRY {
+    next_tvb = tvb_new_subset(tvb, offset_after_length, length, length);
+    trailer_tvb = tvb_new_subset(tvb, offset_after_length + length, -1, -1);
+  }
+  CATCH2(BoundsError, ReportedBoundsError) {
+    /* Either:
+
+	  the packet doesn't have "length" bytes worth of
+	  captured data left in it - or it may not even have
+	  "length" bytes worth of data in it, period -
+	  so the "tvb_new_subset()" creating "next_tvb"
+	  threw an exception
+
+       or
+
+	  the packet has exactly "length" bytes worth of
+	  captured data left in it, so the "tvb_new_subset()"
+	  creating "trailer_tvb" threw an exception.
+
+       In either case, this means that all the data in the frame
+       is within the length value, so we give all the data to the
+       next protocol and have no trailer. */
+    next_tvb = tvb_new_subset(tvb, offset_after_length, -1, length);
+    trailer_tvb = NULL;
+  }
+  ENDTRY;
+
+  /* Dissect the payload either as IPX or as an LLC frame.
+     Catch BoundsError and ReportedBoundsError, so that if the
+     reported length of "next_tvb" was reduced by some dissector
+     before an exception was thrown, we can still put in an item
+     for the trailer. */
+  TRY {
+    if (is_802_2)
+      call_dissector(llc_handle, next_tvb, pinfo, tree);
+    else
+      call_dissector(ipx_handle, next_tvb, pinfo, tree);
+  }
+  CATCH2(BoundsError, ReportedBoundsError) {
+    /* Well, somebody threw an exception.  Add the trailer, if appropriate. */
+    add_trailer(fh_tree, trailer_id, trailer_tvb);
+
+    /* Rethrow the exception, so the "Short Frame" or "Mangled Frame"
+       indication can be put into the tree. */
+    RETHROW;
+
+    /* XXX - RETHROW shouldn't return. */
+    g_assert_not_reached();
+  }
+  ENDTRY;
+
+  add_trailer(fh_tree, trailer_id, trailer_tvb);
+}
+
+static void
+add_trailer(proto_tree *fh_tree, int trailer_id, tvbuff_t *trailer_tvb)
+{
+  /* If there's some bytes left over, mark them. */
+  if (trailer_tvb && fh_tree) {
+    guint trailer_length;
+
+    trailer_length = tvb_length(trailer_tvb);
+    if (trailer_length != 0) {
+      proto_tree_add_item(fh_tree, trailer_id, trailer_tvb, 0,
+			  trailer_length, FALSE);
+    }
+  }
+}
+
+void
+proto_reg_handoff_ieee802_3(void)
+{
+	/*
+	 * Get handles for the IPX and LLC dissectors.
+	 */
+	ipx_handle = find_dissector("ipx");
+	llc_handle = find_dissector("llc");
+}