Fixed ReDoS (Regex Denial of Service)

lib/dns-sync.js

@@ -3,10 +3,11 @@
 var util = require('util'),
     path = require('path'),
     shell = require('shelljs'),
+    RE2 = require('re2'),
     debug = require('debug')('dns-sync');
 
 //source - http://stackoverflow.com/questions/106179/regular-expression-to-match-dns-hostname-or-ip-address
-var ValidHostnameRegex = new RegExp("^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$");
+var ValidHostnameRegex = new RE2("^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$");
 
 // https://nodejs.org/api/dns.html#dns_dns_resolve_hostname_rrtype_callback
 var RRecordTypes = [

package.json

@@ -22,6 +22,7 @@
   "readmeFilename": "README.md",
   "dependencies": {
     "debug": "^4",
+    "re2": "^1.15.4",
     "shelljs": "~0.8"
   },
   "devDependencies": {