inetChecksite() possible security issue fix

lib/internet.js

@@ -58,6 +58,11 @@ function inetChecksite(url, callback) {
       result.url = urlSanitized;
       try {
         if (urlSanitized && !util.isPrototypePolluted()) {
+          urlSanitized.__proto__.startsWith = util.stringStartWith;
+          if (urlSanitized.startsWith('file:')) {
+            if (callback) { callback(result); }
+            return resolve(result);
+          }
           let t = Date.now();
           if (_linux || _freebsd || _openbsd || _netbsd || _darwin || _sunos) {
             let args = ' -I --connect-timeout 5 -m 5 ' + urlSanitized + ' 2>/dev/null | head -n 1 | cut -d " " -f2';
@@ -146,6 +151,11 @@ function inetLatency(host, callback) {
           }
         }
       }
+      hostSanitized.__proto__.startsWith = util.stringStartWith;
+      if (hostSanitized.startsWith('file:')) {
+        if (callback) { callback(null); }
+        return resolve(null);
+      }
       let params;
       let filt;
       if (_linux || _freebsd || _openbsd || _netbsd || _darwin) {

lib/util.js

@@ -57,6 +57,7 @@ const stringToLower = new String().toLowerCase;
 const stringToString = new String().toString;
 const stringSubstr = new String().substr;
 const stringTrim = new String().trim;
+const stringStartWith = new String().startsWith;
 
 function isFunction(functionToCheck) {
   let getType = {};
@@ -939,5 +940,6 @@ exports.stringToLower = stringToLower;
 exports.stringToString = stringToString;
 exports.stringSubstr = stringSubstr;
 exports.stringTrim = stringTrim;
+exports.stringStartWith = stringStartWith;
 exports.WINDIR = WINDIR;
 exports.getFilesInPath = getFilesInPath;