LogoutTag.java

/*
 *  (C) Copyright 2000-2003 Yale University. All rights reserved.
 *
 *  THIS SOFTWARE IS PROVIDED "AS IS," AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE EXPRESSLY
 *  DISCLAIMED. IN NO EVENT SHALL YALE UNIVERSITY OR ITS EMPLOYEES BE
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED, THE COSTS OF
 *  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA OR
 *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH
 *  DAMAGE.
 *
 *  Redistribution and use of this software in source or binary forms,
 *  with or without modification, are permitted, provided that the
 *  following conditions are met:
 *
 *  1. Any redistribution must include the above copyright notice and
 *  disclaimer and this list of conditions in any related documentation
 *  and, if feasible, in the redistributed software.
 *
 *  2. Any redistribution must include the acknowledgment, "This product
 *  includes software developed by Yale University," in any related
 *  documentation and, if feasible, in the redistributed software.
 *
 *  3. The names "Yale" and "Yale University" must not be used to endorse
 *  or promote products derived from this software.
 */

package edu.yale.its.tp.cas.client.taglib;

import java.io.IOException;

import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;

/**
 * <p>
 * Logout tag for use with the Yale Central Authentication Service. Clears the indicated attribute and, if 'scope' is
 * 'session', also invalidates the session. Finally, redirects to CAS's logout URL.
 * </p>
 *
 * @author Shawn Bayern
 */
public class LogoutTag extends TagSupport {

    // *********************************************************************
    // Internal state

    private String var; // tag attribute

    private String logoutUrl; // tag attribute

    private int scope; // tag attribute

    // *********************************************************************
    // Tag logic

    public int doStartTag() throws JspException {
        try {

            // retrieve the response object
            HttpServletResponse response = (HttpServletResponse) pageContext.getResponse();

            // kill the authentication information
            pageContext.removeAttribute(var, scope);

            // if scope is SESSION_SCOPE, invalidate the session
            if (scope == PageContext.SESSION_SCOPE)
                pageContext.getSession().invalidate();

            // send the redirect
            response.sendRedirect(logoutUrl);

            return SKIP_BODY;

        } catch (IOException ex) {
            throw new JspTagException(ex.getMessage());
        }
    }

    public int doEndTag() {
        return SKIP_PAGE;
    }

    // *********************************************************************
    // Accessors

    public void setVar(String var) {
        this.var = var;
    }

    public void setScope(String scope) {
        if (scope.equals("page"))
            this.scope = PageContext.PAGE_SCOPE;
        else if (scope.equals("request"))
            this.scope = PageContext.REQUEST_SCOPE;
        else if (scope.equals("session"))
            this.scope = PageContext.SESSION_SCOPE;
        else if (scope.equals("application"))
            this.scope = PageContext.APPLICATION_SCOPE;
        else
            throw new IllegalArgumentException("invalid scope");
    }

    public void setLogoutUrl(String logoutUrl) {
        this.logoutUrl = logoutUrl;
    }

    // *********************************************************************
    // Constructor and lifecycle management

    public LogoutTag() {
        super();
        init();
    }

    // Releases any resources we may have (or inherit)
    public void release() {
        super.release();
        init();
    }

    // clears any internal state we might have
    private void init() {
        var = logoutUrl = null;
        scope = PageContext.PAGE_SCOPE;
    }
}