Add code to clear the pointer to an object in an OMAPI handle when the

object is freed due to a dereference.  [ISC-Bugs #21306]

4 files changed, 54 insertions, 26 deletions

diff --git a/RELNOTES b/RELNOTES
index ca32bad3..1eda9428 100644
--- a/RELNOTES
+++ b/RELNOTES
@@ -99,6 +99,9 @@ suggested fixes to <dhcp-users@isc.org>.
 - Minor compilation errors - type mismatches, extra semi-colons after macros
   [ISC-Bugs #20884] [ISC-Bugs #20953] [ISC-Bugs #20955]
 
+- Add code to clear the pointer to an object in an OMAPI handle when the
+  object is freed due to a dereference.  [ISC-Bugs #21306]
+
 			Changes since 4.0.2rc1
 
 - None
diff --git a/includes/omapip/omapip_p.h b/includes/omapip/omapip_p.h
index b82e4220..92acd91b 100644
--- a/includes/omapip/omapip_p.h
+++ b/includes/omapip/omapip_p.h
@@ -3,7 +3,8 @@
    Private master include file for the OMAPI library. */
 
 /*
- * Copyright (c) 2004,2007,2009 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2009-2010 by Internet Systems Consortium, Inc. ("ISC") 
+ * Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 1996-2003 by Internet Software Consortium
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -274,6 +275,8 @@ void trace_mr_init (void);
 OMAPI_ARRAY_TYPE_DECL(omapi_listener, omapi_listener_object_t);
 OMAPI_ARRAY_TYPE_DECL(omapi_connection, omapi_connection_object_t);
 
+isc_result_t omapi_handle_clear(omapi_handle_t);
+
 extern int log_priority;
 extern int log_perror;
 extern void (*log_cleanup) (void);
diff --git a/omapip/alloc.c b/omapip/alloc.c
index aeeb3c63..569ef9dd 100644
--- a/omapip/alloc.c
+++ b/omapip/alloc.c
@@ -684,6 +684,13 @@ isc_result_t omapi_object_dereference (omapi_object_t **h,
 /*			if (!hp -> type -> freer) */
 				rc_register (file, line, h, hp,
 					     0, 1, hp -> type -> rc_flag);
+			if (handle_reference) {
+				if (omapi_handle_clear(hp->handle) != 
+				    ISC_R_SUCCESS) {
+					log_debug("Attempt to clear null "
+						  "handle pointer");
+				}
+			}
 			if (hp -> type -> destroy)
 				(*(hp -> type -> destroy)) (hp, file, line);
 			if (hp -> type -> freer)
diff --git a/omapip/handle.c b/omapip/handle.c
index 14209eab..a5049dec 100644
--- a/omapip/handle.c
+++ b/omapip/handle.c
@@ -3,7 +3,8 @@
    Functions for maintaining handles on objects. */
 
 /*
- * Copyright (c) 2004-2007,2009 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2009-2010 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2004-2007 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 1999-2003 by Internet Software Consortium
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -63,9 +64,13 @@
 omapi_handle_table_t *omapi_handle_table;
 omapi_handle_t omapi_next_handle = 1;	/* Next handle to be assigned. */
 
+#define FIND_HAND  0
+#define CLEAR_HAND 1
+
 static isc_result_t omapi_handle_lookup_in (omapi_object_t **,
 					    omapi_handle_t,
-					    omapi_handle_table_t *);
+					    omapi_handle_table_t *,
+					    int);
 static isc_result_t omapi_object_handle_in_table (omapi_handle_t,
 						  omapi_handle_table_t *,
 						  omapi_object_t *);
@@ -239,42 +244,47 @@ static isc_result_t omapi_handle_table_enclose (omapi_handle_table_t **table)
 
 isc_result_t omapi_handle_lookup (omapi_object_t **o, omapi_handle_t h)
 {
-	return omapi_handle_lookup_in (o, h, omapi_handle_table);
+	return(omapi_handle_lookup_in(o, h, omapi_handle_table, FIND_HAND));
 }
 
 static isc_result_t omapi_handle_lookup_in (omapi_object_t **o,
 					    omapi_handle_t h,
-					    omapi_handle_table_t *table)
-
+					    omapi_handle_table_t *table,
+					    int op)
 {
 	omapi_handle_table_t *inner;
 	omapi_handle_t scale, index;
 
-	if (!table || table -> first > h || table -> limit <= h)
-		return ISC_R_NOTFOUND;
+	if (!table || table->first > h || table->limit <= h)
+		return(ISC_R_NOTFOUND);
 	
 	/* If this is a leaf table, just grab the object. */
-	if (table -> leafp) {
+	if (table->leafp) {
 		/* Not there? */
-		if (!table -> children [h - table -> first].object)
-			return ISC_R_NOTFOUND;
-		return omapi_object_reference
-			(o, table -> children [h - table -> first].object,
-			 MDL);
+		if (!table->children[h - table->first].object)
+			return(ISC_R_NOTFOUND);
+		if (op == CLEAR_HAND) {
+			table->children[h - table->first].object = NULL;
+			return(ISC_R_SUCCESS);
+		} else {
+			return(omapi_object_reference
+			       (o, table->children[h - table->first].object,
+				MDL));
+		}
 	}
 
 	/* Scale is the number of handles represented by each child of this
 	   table.   For a leaf table, scale would be 1.   For a first level
 	   of indirection, 120.   For a second, 120 * 120.   Et cetera. */
-	scale = (table -> limit - table -> first) / OMAPI_HANDLE_TABLE_SIZE;
+	scale = (table->limit - table->first) / OMAPI_HANDLE_TABLE_SIZE;
 
 	/* So the next most direct table from this one that contains the
 	   handle must be the subtable of this table whose index into this
 	   table's array of children is the handle divided by the scale. */
-	index = (h - table -> first) / scale;
-	inner = table -> children [index].table;
+	index = (h - table->first) / scale;
+	inner = table->children[index].table;
 
-	return omapi_handle_lookup_in (o, h, table -> children [index].table);
+	return(omapi_handle_lookup_in(o, h, table->children[index].table, op));
 }
 
 /* For looking up objects based on handles that have been sent on the wire. */
@@ -283,13 +293,18 @@ isc_result_t omapi_handle_td_lookup (omapi_object_t **obj,
 {
 	omapi_handle_t h;
 
-	if (handle -> type == omapi_datatype_int)
-		h = handle -> u.integer;
-	else if (handle -> type == omapi_datatype_data &&
-		 handle -> u.buffer.len == sizeof h) {
-		memcpy (&h, handle -> u.buffer.value, sizeof h);
-		h = ntohl (h);
+	if (handle->type == omapi_datatype_int)
+		h = handle->u.integer;
+	else if (handle->type == omapi_datatype_data &&
+		 handle->u.buffer.len == sizeof h) {
+		memcpy(&h, handle->u.buffer.value, sizeof h);
+		h = ntohl(h);
 	} else
-		return ISC_R_INVALIDARG;
-	return omapi_handle_lookup (obj, h);
+		return(ISC_R_INVALIDARG);
+	return(omapi_handle_lookup(obj, h));
+}
+
+isc_result_t omapi_handle_clear(omapi_handle_t h)
+{
+	return(omapi_handle_lookup_in(NULL, h, omapi_handle_table, CLEAR_HAND));
 }