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package org.autoplot.servlet;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.regex.Pattern;
import javax.servlet.http.HttpServletRequest;

/**
 *
 * @author jbf
 */
public class SecurityUtil {
    
    /**
     * check that the person has access to this resource
     * @param request
     * @throws IOException, SecurityException
     */
    public static void checkAllowed( HttpServletRequest request ) throws IOException {
        String who= request.getRemoteAddr();
            if ( who.equals("0:0:0:0:0:0:0:1") ) who= "localhost";
            if ( who.equals("127.0.0.1") ) who= "localhost";
            
        String home= System.getProperty( "AUTOPLOT_SERVLET_HOME" );
            if ( home==null ) home= "/tmp/autoplotservlet/";

            home= new File(home).getCanonicalPath();

            home= home + File.separator; 

            new File(home).mkdirs();

            File hostsallow= new File( home + "allowhosts" );

            if ( !hostsallow.exists() ) {
                PrintWriter write= new PrintWriter( new FileWriter( hostsallow ) );
                write.println("# Initially, only clients from the localhost can connect.  List the allowed clients, one per line.");
                write.println("# Globs like 192.168.0.* may be used.");
                write.println("localhost");
                write.close();
            }

            if ( hostsallow.exists() ) {
                boolean reject= true;
                BufferedReader r= new BufferedReader( new FileReader( hostsallow ) );
                String h= r.readLine();
                while ( h!=null ) {
                    int i= h.indexOf("#");
                    if (i>-1 ) h= h.substring(0,i);
                    if ( h.trim().length()==0 ) {
                        h= r.readLine();
                        continue;
                    }
                    h= h.replaceAll("\\*","\\.\\*");

                    if ( Pattern.matches( h, who ) ) {
                        reject= false;
                    }

                    h= r.readLine();
                }

                if ( reject ) {
                    throw new SecurityException( hostsallow + " does not permit host=\""+who+"\"" );
                }
            } else {
                throw new SecurityException( hostsallow + " file does not exist: "+hostsallow );
            }
    }
    
}