fix: subdomains should be [] if the host is an ip (#808)

Closes: #775

lib/request.js

@@ -5,6 +5,7 @@
  * Module dependencies.
  */
 
+const net = require('net');
 const contentType = require('content-type');
 const stringify = require('url').format;
 const parse = require('parseurl');
@@ -404,7 +405,9 @@ module.exports = {
 
   get subdomains() {
     const offset = this.app.subdomainOffset;
-    return (this.host || '')
+    const hostname = this.hostname;
+    if (net.isIP(hostname)) return [];
+    return hostname
       .split('.')
       .reverse()
       .slice(offset);

test/request/subdomains.js

@@ -14,8 +14,14 @@ describe('req.subdomains', () => {
     req.subdomains.should.eql(['tobi']);
   });
 
-  describe('with no host present', () => {
+  it('should work with no host present', () => {
     const req = request();
     req.subdomains.should.eql([]);
   });
+
+  it('should check if the host is an ip address, even with a port', () => {
+    const req = request();
+    req.header.host = '127.0.0.1:3000';
+    req.subdomains.should.eql([]);
+  });
 });