org.springframework.security.kerberos.web.authentication.SpnegoEntryPoint.java Source code

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Here is the source code for org.springframework.security.kerberos.web.authentication.SpnegoEntryPoint.java

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/*
 * Copyright 2009-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.kerberos.web.authentication;

import javax.servlet.http.HttpServletRequestWrapper;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.http.HttpMethod;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.web.AuthenticationEntryPoint;
import org.springframework.security.web.util.UrlUtils;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Sends back a request for a Negotiate Authentication to the browser.
 *
 * <p>With optional configured <code>forwardUrl</code> it is possible to use form
 * login as fallback authentication.</p>
 *
 * <p>This approach enables security configuration to use SPNEGO in combination
 * with login form as fallback for clients that do not support this kind of
 * authentication. Set Response Code 401 - unauthorized and forward to login
 * page. A useful scenario might be an environment where windows domain is
 * present but it is required to access the application also from non domain
 * client devices. One could use a combination with form based LDAP login.</p>
 *
 * <p>See <code>spnego-with-form-login.xml</code> in
 * spring-security-kerberos-sample for details</p>
 *
 *
 * @author Mike Wiesner
 * @author Andre Schaefer, Namics AG
 * @since 1.0
 * @see SpnegoAuthenticationProcessingFilter
 */
public class SpnegoEntryPoint implements AuthenticationEntryPoint {

    private static final Log LOG = LogFactory.getLog(SpnegoEntryPoint.class);

    private final String forwardUrl;

    private final HttpMethod forwardMethod;

    private final boolean forward;

    /**
     * Instantiates a new spnego entry point. Using this constructor the
     * EntryPoint will Sends back a request for a Negotiate Authentication to
     * the browser without providing a fallback mechanism for login, Use
     * constructor with forwardUrl to provide form based login.
     */
    public SpnegoEntryPoint() {
        this(null);
    }

    /**
     * Instantiates a new spnego entry point. This constructor enables security
     * configuration to use SPNEGO in combination with a fallback page (login form,
     * custom 401 page ...). The forward method will be accessed via GET HTTP
     * method regardless of the HTTP method of the original request.
     *
     * @param forwardUrl
     *            URL where the login page can be found. Should be
     *            relative to the web-app context path (include a leading
     *            {@code /}) and can't be absolute URL.
     */
    public SpnegoEntryPoint(String forwardUrl) {
        this(forwardUrl, HttpMethod.GET);
    }

    /**
     * Instantiates a new spnego entry point. This constructor enables security
     * configuration to use SPNEGO in combination a fallback page (login form,
     * custom 401 page ...). The forward URL will be accessed via provided HTTP
     * method.
     *
     * @param forwardUrl
     *            URL where the login page can be found. Should be
     *            relative to the web-app context path (include a leading
     *            {@code /}) and can't be absolute URL.
     *
     * @param forwardMethod
     *            HTTP method to use when accessing the forward URL
     */
    public SpnegoEntryPoint(String forwardUrl, HttpMethod forwardMethod) {
        if (StringUtils.hasText(forwardUrl)) {
            Assert.isTrue(UrlUtils.isValidRedirectUrl(forwardUrl),
                    "Forward url specified must be a valid forward URL");
            Assert.isTrue(!UrlUtils.isAbsoluteUrl(forwardUrl), "Forward url specified must not be absolute");
            Assert.notNull(forwardMethod, "Http method must be specified");

            this.forwardUrl = forwardUrl;
            this.forwardMethod = forwardMethod;
            this.forward = true;
        } else {
            this.forwardUrl = null;
            this.forwardMethod = null;
            this.forward = false;
        }
    }

    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException ex)
            throws IOException, ServletException {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Add header WWW-Authenticate:Negotiate to " + request.getRequestURL() + ", forward: "
                    + (forward ? forwardUrl : "no"));
        }
        response.addHeader("WWW-Authenticate", "Negotiate");
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);

        if (forward) {
            RequestDispatcher dispatcher = request.getRequestDispatcher(forwardUrl);

            dispatcher.forward(new HttpServletRequestWrapper(request) {
                @Override
                public String getMethod() {
                    return forwardMethod.name();
                }
            }, response);
        } else {
            response.flushBuffer();
        }
    }

}