/* java -Djava.security.auth.login.config=NP.config 
 *      Readclient np
 * H:\nsf>java -Djava.security.auth.login.config=NP.config 
 *             -Djava.security.policy=NPpolicy.txt 
 *             -Djava.security.manager 
 *             Readclient np
 */

/* Authenticates and authorizes a user to read a file
 */

import java.util.Set;
import java.security.Principal;
import java.security.PrivilegedAction;
import javax.security.auth.Subject;
import javax.security.auth.login.LoginContext;
import com.sun.security.auth.NTUserPrincipal;
import javax.security.auth.login.FailedLoginException;

public class Readclient {
  public static void main(String[] args) {
    LoginContext context = null;
    try {
      context = new LoginContext("NP", new NPCallbackHandler());
      context.login();
      Subject subject = context.getSubject();
      System.out.println(subject);
      Set principals = 
          subject.getPrincipals(NamePrincipal.class);
      Object[] p = principals.toArray();
      boolean found = false;
      for (int i = 0; i < p.length; i++)
        if( ((Principal)p[i]).getName().equals(args[0]))
          found = true;
      if(found)
         System.out.println("login succeeded");
      else
         throw new FailedLoginException("Login failed");
      PrivilegedAction action = new ReadFile();
      Subject.doAsPrivileged(subject, action, null);
      context.logout();
    }catch(Exception e) {
      e.printStackTrace();
    }
   }
}