When dissecting an ICMP datagram that contains part of an IP datagram,

hand the (possibly-partial) IP datagram to the IP dissector, as we do
for IPv6 datagrams inside ICMPv6 and CLNP datagrams inside CLNP ER PDUs.

When dissecting IPv6 datagrams inside ICMPv6 and CLNP datagrams inside
CLNP ER PDUs, catch the ReportedLengthError exception and ignore it, as
they don't guarantee that all of the original PDU is present.

svn path=/trunk/; revision=3960

1 files changed, 57 insertions, 5 deletions

diff --git a/packet-ip.c b/packet-ip.c
index dc36acaf10..88e13f9cc6 100644
--- a/packet-ip.c
+++ b/packet-ip.c
@@ -1,7 +1,7 @@
 /* packet-ip.c
  * Routines for IP and miscellaneous IP protocol packet disassembly
  *
- * $Id: packet-ip.c,v 1.140 2001/07/20 07:11:56 guy Exp $
+ * $Id: packet-ip.c,v 1.141 2001/09/27 10:35:40 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -116,6 +116,8 @@ static gint ett_ip_fragment  = -1;
 /* Used by IPv6 as well, so not static */
 dissector_table_t ip_dissector_table;
 
+static dissector_handle_t ip_handle;
+
 static int proto_icmp = -1;
 static int hf_icmp_type = -1;
 static int hf_icmp_code = -1;
@@ -814,7 +816,12 @@ dissect_ip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   iph.ip_off = ntohs(iph.ip_off);
   iph.ip_sum = ntohs(iph.ip_sum);
 
-  /* Length of IP datagram. */
+  /* Length of IP datagram.
+     XXX - what if this is greater than the reported length of the
+     tvbuff?  This could happen, for example, in an IP datagram
+     inside an ICMP datagram; we need to somehow let the
+     dissector we call know that, as it might want to avoid
+     doing its checksumming. */
   len = iph.ip_len;
 
   /* Adjust the length of this tvbuff to include only the IP datagram. */
@@ -1161,6 +1168,13 @@ dissect_icmp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   guint8     num_addrs = 0;
   guint8     addr_entry_size = 0;
   int        i;
+  address    save_dl_src;
+  address    save_dl_dst;
+  address    save_net_src;
+  address    save_net_dst;
+  address    save_src;
+  address    save_dst;
+  tvbuff_t   *next_tvb;
 
   if (check_col(pinfo->fd, COL_PROTOCOL))
     col_set_str(pinfo->fd, COL_PROTOCOL, "ICMP");
@@ -1338,9 +1352,42 @@ dissect_icmp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 	/* Decode the IP header and first 64 bits of data from the
 	   original datagram.
 
-	   XXX - for now, just display it as data; not all dissection
-	   routines can handle a short packet without exploding. */
-	dissect_data(tvb, 8, pinfo, icmp_tree);
+	   Set the columns non-writable, so that the packet list
+	   shows this as an ICMP packet, not as the type of packet
+	   for which the ICMP packet was generated. */
+	col_set_writable(pinfo->fd, FALSE);
+
+	/* Also, save the current values of the addresses, and restore
+	   them when we're finished dissecting the contained packet, so
+	   that the address columns in the summary don't reflect the
+	   contained packet, but reflect this packet instead. */
+	save_dl_src = pinfo->dl_src;
+	save_dl_dst = pinfo->dl_dst;
+	save_net_src = pinfo->net_src;
+	save_net_dst = pinfo->net_dst;
+	save_src = pinfo->src;
+	save_dst = pinfo->dst;
+
+	/* 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. */
+	next_tvb = tvb_new_subset(tvb, 8, -1, -1);
+	TRY {
+	  call_dissector(ip_handle, next_tvb, pinfo, icmp_tree);
+	}
+	CATCH(ReportedBoundsError) {
+	  ; /* do nothing */
+	}
+	ENDTRY;
+
+	/* Restore the addresses. */
+	pinfo->dl_src = save_dl_src;
+	pinfo->dl_dst = save_dl_dst;
+	pinfo->net_src = save_net_src;
+	pinfo->net_dst = save_net_dst;
+	pinfo->src = save_src;
+	pinfo->dst = save_dst;
 	break;
 
       case ICMP_ECHOREPLY:
@@ -1610,5 +1657,10 @@ proto_register_icmp(void)
 void
 proto_reg_handoff_icmp(void)
 {
+  /*
+   * Get handle for the IP dissector.
+   */
+  ip_handle = find_dissector("ip");
+
   dissector_add("ip.proto", IP_PROTO_ICMP, dissect_icmp, proto_icmp);
 }