net: strict checking for internal/net isLegalPort

Add stricter testing for the isLegalPort method in internal/net.
This ensures that odd inputs such as isLegalPort(true) and
isLegalPort([1]) aren't acceptable as valid port inputs.

PR-URL: #5733
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

lib/internal/net.js

@@ -5,7 +5,8 @@ module.exports = { isLegalPort };
 // Check that the port number is not NaN when coerced to a number,
 // is an integer and that it falls within the legal range of port numbers.
 function isLegalPort(port) {
-  if (typeof port === 'string' && port.trim() === '')
+  if ((typeof port !== 'number' && typeof port !== 'string') ||
+      (typeof port === 'string' && port.trim().length === 0))
     return false;
-  return +port === (port >>> 0) && port >= 0 && port <= 0xFFFF;
+  return +port === (+port >>> 0) && port <= 0xFFFF;
 }

test/parallel/test-net-internal.js

@@ -4,12 +4,17 @@
 
 require('../common');
 const assert = require('assert');
-const net = require('internal/net');
-
-assert.strictEqual(net.isLegalPort(''), false);
-assert.strictEqual(net.isLegalPort('0'), true);
-assert.strictEqual(net.isLegalPort(0), true);
-assert.strictEqual(net.isLegalPort(65536), false);
-assert.strictEqual(net.isLegalPort('65535'), true);
-assert.strictEqual(net.isLegalPort(undefined), false);
-assert.strictEqual(net.isLegalPort(null), true);
+const isLegalPort = require('internal/net').isLegalPort;
+
+for (var n = 0; n <= 0xFFFF; n++) {
+  assert(isLegalPort(n));
+  assert(isLegalPort('' + n));
+  assert(`0x${n.toString(16)}`);
+  assert(`0o${n.toString(8)}`);
+  assert(`0b${n.toString(2)}`);
+}
+
+const bad = [-1, 'a', {}, [], false, true, 0xFFFF + 1, Infinity,
+             -Infinity, NaN, undefined, null, '', ' ', 1.1, '0x',
+             '-0x1', '-0o1', '-0b1', '0o', '0b'];
+bad.forEach((i) => assert(!isLegalPort(i)));