com.assignment4.security.SaltFilter.java Source code

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Here is the source code for com.assignment4.security.SaltFilter.java

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/*
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package com.assignment4.security;

/**
 *
 * @author Jai Kiran
 */

import datameer.com.google.common.cache.Cache;
import datameer.com.google.common.cache.CacheBuilder;
import java.io.IOException;
import java.security.SecureRandom;
import java.util.concurrent.TimeUnit;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.lang.RandomStringUtils;

public class SaltFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {

        // Assume its HTTP
        HttpServletRequest httpReq = (HttpServletRequest) request;

        // Check the user session for the salt cache, if none is present we create one
        Cache<String, Boolean> csrfPreventionSaltCache = (Cache<String, Boolean>) httpReq.getSession()
                .getAttribute("csrfPreventionSaltCache");

        if (csrfPreventionSaltCache == null) {
            csrfPreventionSaltCache = CacheBuilder.newBuilder().maximumSize(5000)
                    .expireAfterWrite(20, TimeUnit.MINUTES).build();

            httpReq.getSession().setAttribute("csrfPreventionSaltCache", csrfPreventionSaltCache);
        }

        // Generate the salt and store it in the users cache
        String salt = RandomStringUtils.random(20, 0, 0, true, true, null, new SecureRandom());
        csrfPreventionSaltCache.put(salt, Boolean.TRUE);

        // Add the salt to the current request so it can be used
        // by the page rendered in this request
        httpReq.setAttribute("randId", salt);

        chain.doFilter(request, response);
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void destroy() {
    }
}