android, whitelist only needed websites

Question

I am trying to build a little android app , which can controll web traffic of the device. I want to add a list of websites to this app. this app will allow user to visit only these websites using any browser or any other application. all other network traffic will be blocked or re-routed to some default url from the device .

• This has to be implemented on client end i have no controll/access over server end.

so far i have found that VpnService class of android.net package may let me reroute traffic to some external host but is there a way to locally controll all network traffic and allow only those urls which we want ?