In the heuristic dissector, check to make sure the data being looked at

is available before looking at it, so we don't throw an exception before
we conclude whether the packet is, or isn't, one of ours.

svn path=/trunk/; revision=5424

1 files changed, 15 insertions, 3 deletions

diff --git a/packet-sip.c b/packet-sip.c
index 4f3e2f063b..2fca273ba8 100644
--- a/packet-sip.c
+++ b/packet-sip.c
@@ -15,7 +15,7 @@
  * Copyright 2000, Heikki Vatiainen <hessu@cs.tut.fi>
  * Copyright 2001, Jean-Francois Mule <jfm@clarent.com>
  *
- * $Id: packet-sip.c,v 1.27 2002/05/08 20:29:46 guy Exp $
+ * $Id: packet-sip.c,v 1.28 2002/05/09 07:42:07 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -187,11 +187,23 @@ dissect_sip_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
          * So we first check if the frame is really meant for us.
          */
 
-        /* check for a request */
+        /*
+         * Check for a request.
+         * First, make sure we have enough data to do the check.
+         */
+        if (!tvb_bytes_exist(tvb, 0, SIP2_HDR_LEN)) {
+                /*
+                 * We don't.
+                 */
+                return FALSE;
+        }
 
+        /*
+         * Now see if we have a request header.
+         */
         if (tvb_strneql(tvb, 0, SIP2_HDR, SIP2_HDR_LEN) != 0)  {
                 /*
-                 * Not a request; check for a response.
+                 * We don't, so this isn't a request; check for a response.
                  */
                 eol = tvb_find_line_end(tvb, 0, -1, &next_offset);
                 if ((eol > (gint)SIP2_HDR_LEN) &&