refactor: checkHost (webpack#1619)

* Refactoring checkHost and adding Origin check

* Removing unnecessary header check

* Adding semicolons

Author: orenfromberg

lib/Server.js

@@ -646,7 +646,15 @@ Server.prototype.setContentHeaders = function (req, res, next) {
   next();
 };
 
-Server.prototype.checkHost = function (headers, headerToCheck) {
+Server.prototype.checkHost = function (headers) {
+  return this.checkHeaders(headers, 'host');
+};
+
+Server.prototype.checkOrigin = function (headers) {
+  return this.checkHeaders(headers, 'origin');
+};
+
+Server.prototype.checkHeaders = function (headers, headerToCheck) {
   // allow user to opt-out this security check, at own risk
   if (this.disableHostCheck) {
     return true;
@@ -748,7 +756,7 @@ Server.prototype.listen = function (port, hostname, fn) {
         return;
       }
 
-      if (!this.checkHost(connection.headers) || !this.checkHost(connection.headers, 'origin')) {
+      if (!this.checkHost(connection.headers) || !this.checkOrigin(connection.headers)) {
         this.sockWrite([ connection ], 'error', 'Invalid Host/Origin header');
 
         connection.close();

test/Validation.test.js

@@ -179,7 +179,7 @@ describe('Validation', () => {
         origin: 'https://test.host'
       };
       const server = new Server(compiler, options);
-      if (!server.checkHost(headers, 'origin')) {
+      if (!server.checkOrigin(headers)) {
         throw new Error("Validation didn't fail");
       }
     });