dgram: prefer strict equality, type validation

- Enforces strict comparisons in dgram - bindState should
always be strictly equal to one of the defined constant states,
and newHandle type is a string.

- Check that the argument `type` in createSocket is not null
when it is of type 'object', before using its `type` property.

- Adds a test to check dgram.createSocket is properly
validating its `type` argument.

PR-URL: https://github.com/nodejs/node/pull/8011
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yorkie Liu <yorkiefixer@gmail.com>
Reviewed-By: Jackson Tian <shvyo1987@gmail.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/test/parallel/test-dgram-createSocket-type.js b/test/parallel/test-dgram-createSocket-type.js
new file mode 100644
index 0000000000..1d269ddeda
--- /dev/null
+++ b/test/parallel/test-dgram-createSocket-type.js
@@ -0,0 +1,36 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const dgram = require('dgram');
+const invalidTypes = [
+  'test',
+  ['udp4'],
+  new String('udp4'),
+  1,
+  {},
+  true,
+  false,
+  null,
+  undefined
+];
+const validTypes = [
+  'udp4',
+  'udp6',
+  { type: 'udp4' },
+  { type: 'udp6' }
+];
+
+// Error must be thrown with invalid types
+invalidTypes.forEach((invalidType) => {
+  assert.throws(() => {
+    dgram.createSocket(invalidType);
+  }, /Bad socket type specified/);
+});
+
+// Error must not be thrown with valid types
+validTypes.forEach((validType) => {
+  assert.doesNotThrow(() => {
+    const socket = dgram.createSocket(validType);
+    socket.close();
+  });
+});