From f8269fe365a77c6c3c3e3750d9f8cae9065154b5 Mon Sep 17 00:00:00 2001
From: Myles Borins <mborins@us.ibm.com>
Date: Wed, 3 Feb 2016 16:07:44 -0800
Subject: [PATCH] querystring: check that maxKeys is finite

There was a very subtle change in behavior introduced with 27def4f

In the past if querystring.parse was given Infinity for maxKeys,
everything worked as expected.

Check to see is maxKeys is Infinity before forwarding the value to
String.prototype.split which causes this regression

PR-URL: https://github.com/nodejs/node/pull/5066
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
---
 lib/querystring.js                            |  2 +-
 .../test-querystring-maxKeys-non-finite.js    | 55 +++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 test/parallel/test-querystring-maxKeys-non-finite.js

diff --git a/lib/querystring.js b/lib/querystring.js
index d5d4f175b6bebf..4244d8c18b8122 100644
--- a/lib/querystring.js
+++ b/lib/querystring.js
@@ -215,7 +215,7 @@ QueryString.parse = QueryString.decode = function(qs, sep, eq, options) {
   }
 
   // maxKeys <= 0 means that we should not limit keys count
-  if (maxKeys > 0) {
+  if (maxKeys > 0 && isFinite(maxKeys)) {
     qs = qs.split(sep, maxKeys);
   } else {
     qs = qs.split(sep);
diff --git a/test/parallel/test-querystring-maxKeys-non-finite.js b/test/parallel/test-querystring-maxKeys-non-finite.js
new file mode 100644
index 00000000000000..aab7c45f1b6bed
--- /dev/null
+++ b/test/parallel/test-querystring-maxKeys-non-finite.js
@@ -0,0 +1,55 @@
+'use strict';
+// This test was originally written to test a regression
+// that was introduced by
+// https://github.com/nodejs/node/pull/2288#issuecomment-179543894
+require('../common');
+
+const assert = require('assert');
+const parse = require('querystring').parse;
+
+/*
+taken from express-js/body-parser
+https://github.com/expressjs/body-parser/
+blob/ed25264fb494cf0c8bc992b8257092cd4f694d5e/test/urlencoded.js#L636-L651
+*/
+function createManyParams(count) {
+  var str = '';
+
+  if (count === 0) {
+    return str;
+  }
+
+  str += '0=0';
+
+  for (var i = 1; i < count; i++) {
+    var n = i.toString(36);
+    str += '&' + n + '=' + n;
+  }
+
+  return str;
+}
+
+const count = 10000;
+const originalMaxLength = 1000;
+const params = createManyParams(count);
+
+// thealphanerd
+// 27def4f introduced a change to parse that would cause Inifity
+// to be passed to String.prototype.split as an argument for limit
+// In this instance split will always return an empty array
+// this test confirms that the output of parse is the expected length
+// when passed Infinity as the argument for maxKeys
+const resultInfinity = parse(params, undefined, undefined, {maxKeys: Infinity});
+const resultNaN = parse(params, undefined, undefined, {maxKeys: NaN});
+const resultInfinityString = parse(params, undefined, undefined, {
+  maxKeys: 'Infinity'
+});
+const resultNaNString = parse(params, undefined, undefined, {maxKeys: 'NaN'});
+
+// Non Finite maxKeys should return the length of input
+assert.equal(Object.keys(resultInfinity).length, count);
+assert.equal(Object.keys(resultNaN).length, count);
+// Strings maxKeys should return the maxLength
+// defined by parses internals
+assert.equal(Object.keys(resultInfinityString).length, originalMaxLength);
+assert.equal(Object.keys(resultNaNString).length, originalMaxLength);