Rename the FieldError exception to DissectorError.

Add a DISSECTOR_ASSERT() macro, which is the usual type of assertion
macro, but throws a DissectorError exception with a message giving the
flien and line number and the failed test as a string.  Use that macro
in "alloc_field_info()".

Report that exception in the Info column and the protocol tree, as well
as logging the exception failure with g_warning().

svn path=/trunk/; revision=13078

4 files changed, 31 insertions, 17 deletions

diff --git a/epan/dissectors/packet-frame.c b/epan/dissectors/packet-frame.c
index 0716595f72..e80ce51eda 100644
--- a/epan/dissectors/packet-frame.c
+++ b/epan/dissectors/packet-frame.c
@@ -220,18 +220,23 @@ show_exception(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
 	case ReportedBoundsError:
 		show_reported_bounds_error(tvb, pinfo, tree);
 		break;
-    case FieldError:
+
+	case DissectorError:
 		if (check_col(pinfo->cinfo, COL_INFO))
-			col_append_str(pinfo->cinfo, COL_INFO, "[Dissector Bug]");
+			col_append_fstr(pinfo->cinfo, COL_INFO,
+			    "[Dissector bug, protocol %s: %s]",
+			    pinfo->current_proto, exception_message);
 		proto_tree_add_protocol_format(tree, proto_malformed, tvb, 0, 0,
-				"[FieldError: %s]", exception_message);
-        g_warning("FieldError in packet: %u (%s)", pinfo->fd->num, exception_message);
-        if(exception_message)
-            g_free( (void *) exception_message);
-        break;
-    default:
-        /* XXX - we want to know, if an unknown exception passed until here, don't we? */
-        g_assert_not_reached();
+		    "[Dissector bug, protocol %s: %s]",
+		    pinfo->current_proto, exception_message);
+		g_warning("Dissector bug, protocol %s, in packet %u: %s",
+		    pinfo->current_proto, pinfo->fd->num, exception_message);
+		g_free((void *)exception_message);
+		break;
+
+	default:
+		/* XXX - we want to know, if an unknown exception passed until here, don't we? */
+		g_assert_not_reached();
 	}
 }
 
diff --git a/epan/exceptions.h b/epan/exceptions.h
index 343794382e..f8c7388786 100644
--- a/epan/exceptions.h
+++ b/epan/exceptions.h
@@ -12,7 +12,7 @@
 #define BoundsError		1	/* Index is out of range */
 #define ReportedBoundsError	2	/* Index is beyond reported length (not cap_len) */
 #define TypeError		3	/* During dfilter parsing */
-#define FieldError		4	/* A buggy dissector tried to add a field with invalid parameters */
+#define DissectorError		4	/* A bug was detected in a dissector */
 
 /* Usage:
  *
diff --git a/epan/proto.c b/epan/proto.c
index 100e7dd138..bcc3a877ef 100644
--- a/epan/proto.c
+++ b/epan/proto.c
@@ -2002,7 +2002,6 @@ alloc_field_info(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
 {
 	header_field_info	*hfinfo;
 	field_info		*fi;
-    gchar           *error_descr;
 
 	/*
 	 * We only allow a null tvbuff if the item has a zero length,
@@ -2093,11 +2092,7 @@ alloc_field_info(proto_tree *tree, int hfindex, tvbuff_t *tvb, gint start,
 			g_assert_not_reached();
 		}
 	} else
-	    if(*length < 0) {
-          error_descr = g_strdup_printf("\"%s\" - \"%s\" invalid length: %d %s/%u", 
-              hfinfo->name, hfinfo->abbrev, *length, __FILE__, __LINE__);
-          THROW_MESSAGE(FieldError, error_descr);
-        }
+		DISSECTOR_ASSERT(*length >= 0);
 
 	FIELD_INFO_NEW(fi);
 
diff --git a/epan/proto.h b/epan/proto.h
index 31333f444b..9253450d07 100644
--- a/epan/proto.h
+++ b/epan/proto.h
@@ -78,6 +78,20 @@ typedef struct _protocol protocol_t;
 	}								\
   }
 
+/** Macro used for assertions in dissectors; it doesn't abort, it just
+ * throws a DissectorError exception, with the assertion failure
+ * message as a parameter, so that it can show up in the protocol tree.
+ */
+#define DISSECTOR_ASSERT(expression)  \
+  ((void) ((expression) ? 0 : \
+   __DISSECTOR_ASSERT (expression, __FILE__, __LINE__)))
+
+#define __DISSECTOR_ASSERT_STRINGIFY(s)	# s
+
+#define __DISSECTOR_ASSERT(expression, file, lineno)  \
+  (THROW_MESSAGE(DissectorError, \
+    g_strdup_printf("%s:%u: failed assertion \"%s\"", \
+     file, lineno, __DISSECTOR_ASSERT_STRINGIFY(expression))))
 
 /** GNUC has the ability to check format strings that follow the syntax used in printf and others.
  Hide the differences between different compilers in this GNUC_FORMAT_CHECK macro.