From abe4c34c86ccbe06ff4ecd50774c0205009d4620 Mon Sep 17 00:00:00 2001
From: Kenan Sulayman <kenan@sly.mn>
Date: Fri, 7 Feb 2014 18:18:27 +0100
Subject: [PATCH 1/1] 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 +++-
 test/simple/test-dns.js | 10 ++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/dns.js b/lib/dns.js
index cbba372..d77159d 100644
--- a/lib/dns.js
+++ b/lib/dns.js
@@ -185,9 +185,11 @@ exports.resolve = function(hostname, type_, callback_) {
   if (util.isString(type_)) {
     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 (util.isFunction(resolver)) {
diff --git a/test/simple/test-dns.js b/test/simple/test-dns.js
index 9283bab..e7dce4b 100644
--- a/test/simple/test-dns.js
+++ b/test/simple/test-dns.js
@@ -60,3 +60,13 @@ assert.deepEqual(dns.getServers(), portsExpected);
 
 assert.doesNotThrow(function () { dns.setServers([]); });
 assert.deepEqual(dns.getServers(), []);
+
+assert.throws(
+  function() {
+    dns.resolve('test.com', [], new Function);
+  },
+  function(err) {
+    return !(err instanceof TypeError);
+  },
+  "Unexpected error"
+);
-- 
2.7.4