Allow storage proxy to work with IPv4

Storage proxy signed cookies would get assigned to wrong domain if
configured host name is IPv4 address, thus blocking display of assets.
Problem is in `psl` package which parses IPv4 addresses, thus producing
wrong domains.
Fix detects IPv4 addresses using regular expression and just returns
`null` for domain.

Author: droguljic

server/shared/storage/proxy/mw.js

@@ -7,6 +7,13 @@ const path = require('path');
 const router = require('express').Router();
 const psl = require('psl');
 
+const IPV4_REGEX = /^((25[0-5]|(2[0-4]|1[0-9]|[1-9]|)[0-9])(\.(?!$)|$)){4}$/;
+
+function getDomain() {
+  if (IPV4_REGEX.test(config.hostname)) return null;
+  return psl.parse(config.hostname).domain;
+}
+
 module.exports = (storage, proxy) => {
   function getFile(req, res, next) {
     const key = req.params[0];
@@ -24,7 +31,7 @@ module.exports = (storage, proxy) => {
     if (proxy.hasCookies(req.cookies, repositoryId)) return next();
     const maxAge = 1000 * 60 * 60; // 1 hour in ms
     const cookies = proxy.getSignedCookies(repositoryId, maxAge);
-    const { domain } = psl.parse(config.hostname);
+    const domain = getDomain();
     const cookieOptions = { domain, maxAge, httpOnly: true };
     Object.entries(cookies).forEach(([cookie, value]) => {
       res.cookie(cookie, value, cookieOptions);