fix register with invalid from and to header (#84)

lib/middleware.js

@@ -24,6 +24,12 @@ const checkCache = async(req, res, next) => {
   const {logger} = req.locals;
   const registration = req.registration;
   const uri = parseUri(registration.aor);
+  // if cannot parse uri, then we cannot proceed
+  if (!uri) {
+    return res.send(403, {headers: {
+      'X-Reason': 'Invalid address of record'
+    }});
+  }
   const aor = `${uri.user}@${uri.host}`;
   req.locals.realm = uri.host;