ClientInfoFilter.java

/**
 * Copyright (c) Codice Foundation
 * <p>
 * This is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser
 * General Public License as published by the Free Software Foundation, either version 3 of the
 * License, or any later version.
 * <p>
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details. A copy of the GNU Lesser General Public License
 * is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 */
package org.codice.ddf.platform.filter.clientinfo;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.apache.shiro.util.ThreadContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This servlet filter extracts client-specific information and places it in the shiro {@link ThreadContext}
 * so it can be forwarded to useful areas of interest. Also contains the constants for working with
 * the client info map.
 * <p>
 * The information currently all comes from the servlet API; specifically a select few getters
 * within {@link javax.servlet.ServletRequest}. The format of the keys follows the format of java
 * beans. The keys are camel-cased names without the preceeding 'get' found in the method name.
 * <p>
 * For example, the key associated with {@link javax.servlet.ServletRequest#getRemoteAddr()} would
 * be the string {@code remoteAddr}.
 * <p>
 * The only exception to this rule, {@link ClientInfoFilter#CLIENT_INFO_KEY}, which holds a value string
 * of {@code client-info}, is the key used to access the entire client information map. It may contain
 * different kinds of data that does not necessarily correlate to the servlet API.
 */
public class ClientInfoFilter implements Filter {

    private static final Logger LOGGER = LoggerFactory.getLogger(ClientInfoFilter.class);

    public static final String CLIENT_INFO_KEY = "client-info";

    public static final String SERVLET_REMOTE_ADDR = "remoteAddr";

    public static final String SERVLET_REMOTE_HOST = "remoteHost";

    public static final String SERVLET_SCHEME = "scheme";

    public static final String SERVLET_CONTEXT_PATH = "contextPath";

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

    @Override
    public void destroy() {
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
            FilterChain filterChain) throws IOException, ServletException {
        ThreadContext.put(CLIENT_INFO_KEY, createClientInfoMap(servletRequest));
        try {
            filterChain.doFilter(servletRequest, servletResponse);
        } finally {
            ThreadContext.remove(CLIENT_INFO_KEY);
        }
    }

    private Map<String, String> createClientInfoMap(ServletRequest request) {
        Map<String, String> clientInfoMap = new HashMap<>();
        clientInfoMap.put(SERVLET_REMOTE_ADDR, request.getRemoteAddr());
        clientInfoMap.put(SERVLET_REMOTE_HOST, request.getRemoteHost());
        clientInfoMap.put(SERVLET_SCHEME, request.getScheme());
        ServletContext servletContext = request.getServletContext();
        if (servletContext != null) {
            clientInfoMap.put(SERVLET_CONTEXT_PATH, servletContext.getContextPath());
        }
        LOGGER.debug("Creating client info map with the following pairs, {}",
                clientInfoMap.toString());
        return clientInfoMap;
    }
}