From 722a27bfefb278dec879505e0f067bbdc6482c2c Mon Sep 17 00:00:00 2001
From: Neel Goyal <ngoyal@verisign.com>
Date: Fri, 10 Jan 2014 10:28:28 -0500
Subject: [PATCH] fix for issue #49

---
 src/general.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/general.c b/src/general.c
index 58b632d7..5ea272bb 100644
--- a/src/general.c
+++ b/src/general.c
@@ -10,7 +10,7 @@
 /*
  * Copyright (c) 2013, Versign, Inc.
  * All rights reserved.
- * 
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  * * Redistributions of source code must retain the above copyright
@@ -196,7 +196,7 @@ ub_resolve_callback(void *arg, int err, ldns_buffer * result, int sec,
 	 */
 	if (netreq->state == NET_REQ_NOT_SENT) {
 		/* just do a very short timer since this was called immediately.
-		 * we can make this less hacky, but it gets interesting when multiple 
+		 * we can make this less hacky, but it gets interesting when multiple
 		 * netreqs need to be issued and some resolve immediately vs. not.
 		 */
 		struct timeval tv;
@@ -329,13 +329,18 @@ getdns_general(struct getdns_context *context,
 {
 	int extcheck = GETDNS_RETURN_GOOD;
 
-	if (!context || !context->event_base_async || callback == NULL) {
+	if (!context || !context->event_base_async) {
 		/* Can't do async without an event loop
 		 * or callback
 		 */
 		return GETDNS_RETURN_BAD_CONTEXT;
 	}
 
+    /* ensure callback is not NULL */
+    if (!callback) {
+         return GETDNS_RETURN_INVALID_PARAMETER;
+    }
+
 	extcheck = validate_extensions(extensions);
 	if (extcheck != GETDNS_RETURN_GOOD)
 		return extcheck;