Java tutorial
/* * Licensed to Jasig under one or more contributor license * agreements. See the NOTICE file distributed with this work * for additional information regarding copyright ownership. * Jasig licenses this file to you 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 the following location: * * 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.jasig.cas.client.session; import java.util.Arrays; import java.util.List; import java.util.zip.Inflater; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import org.apache.commons.codec.binary.Base64; import org.apache.commons.lang.StringUtils; import org.jasig.cas.client.util.CommonUtils; import org.jasig.cas.client.util.XmlUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Performs CAS single sign-out operations in an API-agnostic fashion. * * @author Marvin S. Addison * @version $Revision$ $Date$ * @since 3.1.12 * */ public final class SingleSignOutHandler { public final static String DEFAULT_ARTIFACT_PARAMETER_NAME = "ticket"; public final static String DEFAULT_LOGOUT_PARAMETER_NAME = "logoutRequest"; public final static String DEFAULT_FRONT_LOGOUT_PARAMETER_NAME = "SAMLRequest"; public final static String DEFAULT_RELAY_STATE_PARAMETER_NAME = "RelayState"; private final static int DECOMPRESSION_FACTOR = 10; /** Logger instance */ private final Logger logger = LoggerFactory.getLogger(getClass()); /** Mapping of token IDs and session IDs to HTTP sessions */ private SessionMappingStorage sessionMappingStorage = new HashMapBackedSessionMappingStorage(); /** The name of the artifact parameter. This is used to capture the session identifier. */ private String artifactParameterName = DEFAULT_ARTIFACT_PARAMETER_NAME; /** Parameter name that stores logout request for back channel SLO */ private String logoutParameterName = DEFAULT_LOGOUT_PARAMETER_NAME; /** Parameter name that stores logout request for front channel SLO */ private String frontLogoutParameterName = DEFAULT_FRONT_LOGOUT_PARAMETER_NAME; /** Parameter name that stores the state of the CAS server webflow for the callback */ private String relayStateParameterName = DEFAULT_RELAY_STATE_PARAMETER_NAME; /** The prefix url of the CAS server */ private String casServerUrlPrefix; private boolean artifactParameterOverPost = false; private boolean eagerlyCreateSessions = true; private List<String> safeParameters; public void setSessionMappingStorage(final SessionMappingStorage storage) { this.sessionMappingStorage = storage; } public void setArtifactParameterOverPost(final boolean artifactParameterOverPost) { this.artifactParameterOverPost = artifactParameterOverPost; } public SessionMappingStorage getSessionMappingStorage() { return this.sessionMappingStorage; } /** * @param name Name of the authentication token parameter. */ public void setArtifactParameterName(final String name) { this.artifactParameterName = name; } /** * @param name Name of parameter containing CAS logout request message for back channel SLO. */ public void setLogoutParameterName(final String name) { this.logoutParameterName = name; } /** * @param casServerUrlPrefix The prefix url of the CAS server. */ public void setCasServerUrlPrefix(final String casServerUrlPrefix) { this.casServerUrlPrefix = casServerUrlPrefix; } /** * @param name Name of parameter containing CAS logout request message for front channel SLO. */ public void setFrontLogoutParameterName(final String name) { this.frontLogoutParameterName = name; } /** * @param name Name of parameter containing the state of the CAS server webflow. */ public void setRelayStateParameterName(final String name) { this.relayStateParameterName = name; } public void setEagerlyCreateSessions(final boolean eagerlyCreateSessions) { this.eagerlyCreateSessions = eagerlyCreateSessions; } /** * Initializes the component for use. */ public void init() { CommonUtils.assertNotNull(this.artifactParameterName, "artifactParameterName cannot be null."); CommonUtils.assertNotNull(this.logoutParameterName, "logoutParameterName cannot be null."); CommonUtils.assertNotNull(this.frontLogoutParameterName, "frontLogoutParameterName cannot be null."); CommonUtils.assertNotNull(this.sessionMappingStorage, "sessionMappingStorage cannot be null."); CommonUtils.assertNotNull(this.relayStateParameterName, "relayStateParameterName cannot be null."); CommonUtils.assertNotNull(this.casServerUrlPrefix, "casServerUrlPrefix cannot be null."); if (this.artifactParameterOverPost) { this.safeParameters = Arrays.asList(this.logoutParameterName, this.artifactParameterName); } else { this.safeParameters = Arrays.asList(this.logoutParameterName); } } /** * Determines whether the given request contains an authentication token. * * @param request HTTP reqest. * * @return True if request contains authentication token, false otherwise. */ private boolean isTokenRequest(final HttpServletRequest request) { return CommonUtils .isNotBlank(CommonUtils.safeGetParameter(request, this.artifactParameterName, this.safeParameters)); } /** * Determines whether the given request is a CAS back channel logout request. * * @param request HTTP request. * * @return True if request is logout request, false otherwise. */ private boolean isBackChannelLogoutRequest(final HttpServletRequest request) { return "POST".equals(request.getMethod()) && !isMultipartRequest(request) && CommonUtils .isNotBlank(CommonUtils.safeGetParameter(request, this.logoutParameterName, this.safeParameters)); } /** * Determines whether the given request is a CAS front channel logout request. * * @param request HTTP request. * * @return True if request is logout request, false otherwise. */ private boolean isFrontChannelLogoutRequest(final HttpServletRequest request) { return "GET".equals(request.getMethod()) && CommonUtils.isNotBlank(CommonUtils.safeGetParameter(request, this.frontLogoutParameterName)); } /** * Process a request regarding the SLO process: record the session or destroy it. * * @param request the incoming HTTP request. * @param response the HTTP response. * @return if the request should continue to be processed. */ public boolean process(final HttpServletRequest request, final HttpServletResponse response) { if (isTokenRequest(request)) { logger.trace("Received a token request"); recordSession(request); return true; } else if (isBackChannelLogoutRequest(request)) { logger.trace("Received a back channel logout request"); destroySession(request); return false; } else if (isFrontChannelLogoutRequest(request)) { logger.trace("Received a front channel logout request"); destroySession(request); // redirection url to the CAS server final String redirectionUrl = computeRedirectionToServer(request); if (redirectionUrl != null) { CommonUtils.sendRedirect(response, redirectionUrl); } return false; } else { logger.trace("Ignoring URI for logout: {}", request.getRequestURI()); return true; } } /** * Associates a token request with the current HTTP session by recording the mapping * in the the configured {@link SessionMappingStorage} container. * * @param request HTTP request containing an authentication token. */ private void recordSession(final HttpServletRequest request) { final HttpSession session = request.getSession(this.eagerlyCreateSessions); if (session == null) { logger.debug( "No session currently exists (and none created). Cannot record session information for single sign out."); return; } final String token = CommonUtils.safeGetParameter(request, this.artifactParameterName, this.safeParameters); logger.debug("Recording session for token {}", token); try { this.sessionMappingStorage.removeBySessionById(session.getId()); } catch (final Exception e) { // ignore if the session is already marked as invalid. Nothing we can do! } sessionMappingStorage.addSessionById(token, session); } /** * Uncompress a logout message (base64 + deflate). * * @param originalMessage the original logout message. * @return the uncompressed logout message. */ private String uncompressLogoutMessage(final String originalMessage) { final byte[] binaryMessage = Base64.decodeBase64(originalMessage); Inflater decompresser = null; try { // decompress the bytes decompresser = new Inflater(); decompresser.setInput(binaryMessage); final byte[] result = new byte[binaryMessage.length * DECOMPRESSION_FACTOR]; final int resultLength = decompresser.inflate(result); // decode the bytes into a String return new String(result, 0, resultLength, "UTF-8"); } catch (final Exception e) { logger.error("Unable to decompress logout message", e); throw new RuntimeException(e); } finally { if (decompresser != null) { decompresser.end(); } } } /** * Destroys the current HTTP session for the given CAS logout request. * * @param request HTTP request containing a CAS logout message. */ private void destroySession(final HttpServletRequest request) { final String logoutMessage; // front channel logout -> the message needs to be base64 decoded + decompressed if (isFrontChannelLogoutRequest(request)) { logoutMessage = uncompressLogoutMessage( CommonUtils.safeGetParameter(request, this.frontLogoutParameterName)); } else { logoutMessage = CommonUtils.safeGetParameter(request, this.logoutParameterName, this.safeParameters); } logger.trace("Logout request:\n{}", logoutMessage); final String token = XmlUtils.getTextForElement(logoutMessage, "SessionIndex"); if (CommonUtils.isNotBlank(token)) { final HttpSession session = this.sessionMappingStorage.removeSessionByMappingId(token); if (session != null) { String sessionID = session.getId(); logger.debug("Invalidating session [{}] for token [{}]", sessionID, token); try { session.invalidate(); } catch (final IllegalStateException e) { logger.debug("Error invalidating session.", e); } try { request.logout(); } catch (final ServletException e) { logger.debug("Error performing request.logout."); } } } } /** * Compute the redirection url to the CAS server when it's a front channel SLO * (depending on the relay state parameter). * * @param request The HTTP request. * @return the redirection url to the CAS server. */ private String computeRedirectionToServer(final HttpServletRequest request) { final String relayStateValue = CommonUtils.safeGetParameter(request, this.relayStateParameterName); // if we have a state value -> redirect to the CAS server to continue the logout process if (StringUtils.isNotBlank(relayStateValue)) { final StringBuilder buffer = new StringBuilder(); buffer.append(casServerUrlPrefix); if (!this.casServerUrlPrefix.endsWith("/")) { buffer.append("/"); } buffer.append("logout?_eventId=next&"); buffer.append(this.relayStateParameterName); buffer.append("="); buffer.append(CommonUtils.urlEncode(relayStateValue)); final String redirectUrl = buffer.toString(); logger.debug("Redirection url to the CAS server: {}", redirectUrl); return redirectUrl; } return null; } private boolean isMultipartRequest(final HttpServletRequest request) { return request.getContentType() != null && request.getContentType().toLowerCase().startsWith("multipart"); } }