From 2ee86c624ecd6b9dbaad10989143325fc64778cd Mon Sep 17 00:00:00 2001
From: Kenan Sulayman <kenan@sly.mn>
Date: Fri, 7 Feb 2014 18:18:27 +0100
Subject: [PATCH] dns: verify argument is valid function in resolve
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Don't use argument as callback if it's not a valid callback function.
Throw a valid exception instead explaining the issue. Adds to #7070
("DNS — Throw meaningful error(s)").
---
 lib/dns.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/dns.js b/lib/dns.js
index 15ee6a4362..dcf2128e28 100644
--- a/lib/dns.js
+++ b/lib/dns.js
@@ -184,9 +184,11 @@ exports.resolve = function(domain, type_, callback_) {
   if (typeof type_ == 'string') {
     resolver = resolveMap[type_];
     callback = callback_;
-  } else {
+  } else if (util.isFunction(type_)) {
     resolver = exports.resolve4;
     callback = type_;
+  } else {
+    throw new Error('Type must be a string')
   }
 
   if (typeof resolver === 'function') {