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, 23 insertions, 80 deletions

diff --git a/packet-eth.c b/packet-eth.c
index 4fab51b777..5e1e34e064 100644
--- a/packet-eth.c
+++ b/packet-eth.c
@@ -1,7 +1,7 @@
 /* packet-eth.c
  * Routines for ethernet packet disassembly
  *
- * $Id: packet-eth.c,v 1.59 2001/01/21 22:10:22 guy Exp $
+ * $Id: packet-eth.c,v 1.60 2001/02/08 07:08:05 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@zing.org>
@@ -36,6 +36,7 @@
 #include "etypes.h"
 #include "resolv.h"
 #include "packet-eth.h"
+#include "packet-ieee8023.h"
 #include "packet-ipx.h"
 #include "packet-isl.h"
 #include "packet-llc.h"
@@ -55,8 +56,6 @@ static gint ett_ieee8023 = -1;
 static gint ett_ether2 = -1;
 
 static dissector_handle_t isl_handle;
-static dissector_handle_t ipx_handle;
-static dissector_handle_t llc_handle;
 
 #define ETH_HEADER_SIZE	14
 
@@ -151,11 +150,9 @@ dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   const guint8		*pd;
 
   guint16		etype;
-  volatile int		ethhdr_type;	/* the type of Ethernet frame */
+  volatile gboolean	is_802_2;
   int			eth_offset;
   volatile guint16  	length;
-  tvbuff_t		*volatile next_tvb;
-  tvbuff_t		*volatile trailer_tvb;
   proto_tree		*volatile fh_tree = NULL;
 
   tvb_compat(tvb, &pd, (int*)&eth_offset);
@@ -178,16 +175,29 @@ dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   if (etype <= IEEE_802_3_MAX_LEN) {
     length = etype;
 
+    /* Oh, yuck.  Cisco ISL frames require special interpretation of the
+       destination address field; fortunately, they can be recognized by
+       checking the first 5 octets of the destination address, which are
+       01-00-0C-00-00 for ISL frames. */
+    if (	tvb_get_guint8(tvb, 0) == 0x01 &&
+		tvb_get_guint8(tvb, 1) == 0x00 &&
+		tvb_get_guint8(tvb, 2) == 0x0C &&
+		tvb_get_guint8(tvb, 3) == 0x00 &&
+		tvb_get_guint8(tvb, 4) == 0x00 ) {
+      call_dissector(isl_handle, tvb, pinfo, tree);
+      return;
+    }
+
     /* Is there an 802.2 layer? I can tell by looking at the first 2
        bytes after the 802.3 header. If they are 0xffff, then what
        follows the 802.3 header is an IPX payload, meaning no 802.2.
        (IPX/SPX is they only thing that can be contained inside a
        straight 802.3 packet). A non-0xffff value means that there's an
        802.2 layer inside the 802.3 layer */
-    ethhdr_type = ETHERNET_802_2;
+    is_802_2 = TRUE;
     TRY {
 	    if (tvb_get_ntohs(tvb, 14) == 0xffff) {
-	      ethhdr_type = ETHERNET_802_3;
+	      is_802_2 = FALSE;
 	    }
     }
     CATCH2(BoundsError, ReportedBoundsError) {
@@ -196,26 +206,13 @@ dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
     }
     ENDTRY;
 
-    /* Oh, yuck.  Cisco ISL frames require special interpretation of the
-       destination address field; fortunately, they can be recognized by
-       checking the first 5 octets of the destination address, which are
-       01-00-0C-00-00 for ISL frames. */
-    if (	tvb_get_guint8(tvb, 0) == 0x01 &&
-		tvb_get_guint8(tvb, 1) == 0x00 &&
-		tvb_get_guint8(tvb, 2) == 0x0C &&
-		tvb_get_guint8(tvb, 3) == 0x00 &&
-		tvb_get_guint8(tvb, 4) == 0x00 ) {
-      call_dissector(isl_handle, tvb, pinfo, tree);
-      return;
-    }
-
     if (check_col(pinfo->fd, COL_INFO)) {
       col_add_fstr(pinfo->fd, COL_INFO, "IEEE 802.3 %s",
-		(ethhdr_type == ETHERNET_802_3 ? "Raw " : ""));
+		(is_802_2 ? "" : "Raw "));
     }
     if (tree) {
       ti = proto_tree_add_protocol_format(tree, proto_eth, tvb, 0, ETH_HEADER_SIZE,
-		"IEEE 802.3 %s", (ethhdr_type == ETHERNET_802_3 ? "Raw " : ""));
+		"IEEE 802.3 %s", (is_802_2 ? "" : "Raw "));
 
       fh_tree = proto_item_add_subtree(ti, ett_ieee8023);
 
@@ -225,8 +222,6 @@ dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 /* add items for eth.addr filter */
       proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 0, 6, dst);
       proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src);
-
-      proto_tree_add_uint(fh_tree, hf_eth_len, tvb, 12, 2, length);
     }
 
     /* Convert the LLC length from the 802.3 header to a total
@@ -243,56 +238,9 @@ dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
     if (pinfo->captured_len > length)
       pinfo->captured_len = length;
 
-    /* Give the next dissector only 'length' number of bytes */
-    TRY {
-      next_tvb = tvb_new_subset(tvb, ETH_HEADER_SIZE, etype, etype);
-      trailer_tvb = tvb_new_subset(tvb, ETH_HEADER_SIZE + etype, -1, -1);
-    }
-    CATCH2(BoundsError, ReportedBoundsError) {
-      /* Either:
-
-	    the packet doesn't have "etype" bytes worth of
-	    captured data left in it - or it may not even have
-	    "etype" bytes worth of data in it, period -
-	    so the "tvb_new_subset()" creating "next_tvb"
-	    threw an exception
-
-	 or
-
-	    the packet has exactly "etype" 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, ETH_HEADER_SIZE, -1, etype);
-      trailer_tvb = NULL;
-    }
-    ENDTRY;
-
-    /* Dissect the payload either as IPX or as an LLC frame. */
-    switch (ethhdr_type) {
-      case ETHERNET_802_3:
-        call_dissector(ipx_handle, next_tvb, pinfo, tree);
-        break;
-      case ETHERNET_802_2:
-        call_dissector(llc_handle, next_tvb, pinfo, tree);
-        break;
-    }
-
-    /* If there's some bytes left over, mark them. */
-    if (trailer_tvb && tree) {
-      guint trailer_length;
-
-      trailer_length = tvb_length(trailer_tvb);
-      if (trailer_length != 0) {
-	proto_tree_add_item(fh_tree, hf_eth_trailer, trailer_tvb, 0,
-			    trailer_length, FALSE);
-      }
-    }
+    dissect_802_3(etype, is_802_2, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree,
+		  hf_eth_len, hf_eth_trailer);
   } else {
-    ethhdr_type = ETHERNET_II;
     if (check_col(pinfo->fd, COL_INFO))
       col_set_str(pinfo->fd, COL_INFO, "Ethernet II");
     if (tree) {
@@ -308,9 +256,6 @@ dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
       proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src);
     }
 
-    next_tvb = NULL;	/* "ethertype()" will create the next tvb for us */
-    trailer_tvb = NULL;	/* we don't know how big the trailer is */
-
     ethertype(etype, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree, hf_eth_type,
           hf_eth_trailer);
   }
@@ -362,11 +307,9 @@ void
 proto_reg_handoff_eth(void)
 {
 	/*
-	 * Get handles for the ISL, IPX, and LLC dissectors.
+	 * Get a handle for the ISL dissector.
 	 */
 	isl_handle = find_dissector("isl");
-	ipx_handle = find_dissector("ipx");
-	llc_handle = find_dissector("llc");
 
 	dissector_add("wtap_encap", WTAP_ENCAP_ETHERNET, dissect_eth,
 	    proto_eth);