tls: convertProtocols() error handling

The convertProtocols() function now throws a range error when the byte
length of a protocol is too long to fit in a Buffer.

Also added a test case in test/parallel/test-tls-basic-validations.js
to cover this.

lib/tls.js

@@ -21,7 +21,10 @@
 
 'use strict';
 
-const { ERR_TLS_CERT_ALTNAME_INVALID } = require('internal/errors').codes;
+const {
+  ERR_TLS_CERT_ALTNAME_INVALID,
+  ERR_OUT_OF_RANGE
+} = require('internal/errors').codes;
 const internalUtil = require('internal/util');
 const internalTLS = require('internal/tls');
 internalUtil.assertCrypto();
@@ -60,6 +63,9 @@ function convertProtocols(protocols) {
   const lens = new Array(protocols.length);
   const buff = Buffer.allocUnsafe(protocols.reduce((p, c, i) => {
     var len = Buffer.byteLength(c);
+    if (len > 255) {
+      throw new ERR_OUT_OF_RANGE('byte length of a protocol', '< 255', len);
+    }
     lens[i] = len;
     return p + 1 + len;
   }, 0));

test/parallel/test-tls-basic-validations.js

@@ -102,3 +102,16 @@ common.expectsError(
     assert(out.ALPNProtocols.equals(Buffer.from(expectView)));
   }
 }
+
+{
+  const protocols = [(new String('a')).repeat(500)];
+  const out = {};
+  common.expectsError(
+    () => tls.convertALPNProtocols(protocols, out),
+    {
+      code: 'ERR_OUT_OF_RANGE',
+      message: 'The value of "byte length of a protocol" is out ' +
+        'of range. It must be < 255. Received 500'
+    }
+  );
+}