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/*

 * Copyright 2008, 2009 Electronic Business Systems Ltd.

 *

 * This file is part of GSS.

 *

 * GSS is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * GSS 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with GSS.  If not, see <http://www.gnu.org/licenses/>.

 */

package gr.ebs.gss.server;

import static gr.ebs.gss.server.configuration.GSSConfigurationFactory.getConfiguration;

import gr.ebs.gss.client.exceptions.DuplicateNameException;

import gr.ebs.gss.client.exceptions.ObjectNotFoundException;

import gr.ebs.gss.client.exceptions.RpcException;

import gr.ebs.gss.server.domain.Nonce;

import gr.ebs.gss.server.domain.User;

import gr.ebs.gss.server.ejb.ExternalAPI;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.UnsupportedEncodingException;

import java.net.URI;

import java.net.URISyntaxException;

import java.net.URLEncoder;

import java.util.Formatter;

import javax.naming.Context;

import javax.naming.InitialContext;

import javax.naming.NamingException;

import javax.rmi.PortableRemoteObject;

import javax.servlet.http.Cookie;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.codec.binary.Base64;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

/**

 * The servlet that handles user logins.

 *

 * @author past

 */

public class Login extends HttpServlet {

        /**

         * The request parameter name for the nonce.

         */

        private static final String NONCE_PARAM = "nonce";

        /**

         * The request parameter name for the URL to redirect

         * to after authentication.

         */

        private static final String NEXT_URL_PARAM = "next";

        /**

         * The serial version UID of the class.

         */

        private static final long serialVersionUID = 1L;

        /**

         * The name of the authentication cookie.

         */

        private static final String AUTH_COOKIE = "_gss_a";

        /**

         * The separator character for the authentication cookie.

         */

        private static final char COOKIE_SEPARATOR = '|';

        /**

         * The name of the the webdav cookie.

         */

        public static final String WEBDAV_COOKIE = "_gss_wd";

        /**

         * The logger.

         */

        private static Log logger = LogFactory.getLog(Login.class);

        /**

         * A helper method that retrieves a reference to the ExternalAPI bean and

         * stores it for future use.

         *

         * @return an ExternalAPI instance

         * @throws RpcException in case an error occurs

         */

        private ExternalAPI getService() throws RpcException {

                try {

                        final Context ctx = new InitialContext();

                        final Object ref = ctx.lookup(getConfiguration().getString("externalApiPath"));

                        return (ExternalAPI) PortableRemoteObject.narrow(ref, ExternalAPI.class);

                } catch (final NamingException e) {

                        logger.error("Unable to retrieve the ExternalAPI EJB", e);

                        throw new RpcException("An error occurred while contacting the naming service");

                }

        }

        /**

         * Return the name of the service.

         */

        private String getServiceName() {

                return getConfiguration().getString("serviceName", "GSS");

        }

        @Override

        public void service(HttpServletRequest request, HttpServletResponse response) throws IOException {

                // Fetch the next URL to display, if any.

                String nextUrl = request.getParameter(NEXT_URL_PARAM);

                // Fetch the supplied nonce, if any.

                String nonce = request.getParameter(NONCE_PARAM);

                String[] attrs = new String[] {"REMOTE_USER", "HTTP_SHIB_INETORGPERSON_DISPLAYNAME",

                                        "HTTP_SHIB_INETORGPERSON_GIVENNAME", "HTTP_SHIB_PERSON_COMMONNAME",

                                        "HTTP_SHIB_PERSON_SURNAME", "HTTP_SHIB_INETORGPERSON_MAIL",

                                        "HTTP_SHIB_EP_UNSCOPEDAFFILIATION"};

                StringBuilder buf = new StringBuilder("Shibboleth Attributes\n");

                for (String attr: attrs)

                        buf.append(attr+": ").append(request.getAttribute(attr)).append('\n');

                logger.info(buf);

                if (logger.isDebugEnabled()) {

                        buf = new StringBuilder("Shibboleth Attributes as bytes\n");

                        for (String attr: attrs)

                                if (request.getAttribute(attr) != null)

                                        buf.append(attr+": ").append(getHexString(request.getAttribute(attr).toString().getBytes("UTF-8"))).append('\n');

                        logger.debug(buf);

                }

                User user = null;

                response.setContentType("text/html");

                Object usernameAttr = request.getAttribute("REMOTE_USER");

                Object nameAttr = request.getAttribute("HTTP_SHIB_INETORGPERSON_DISPLAYNAME");

                Object givennameAttr = request.getAttribute("HTTP_SHIB_INETORGPERSON_GIVENNAME"); // Multi-valued

                Object cnAttr = request.getAttribute("HTTP_SHIB_PERSON_COMMONNAME"); // Multi-valued

                Object snAttr = request.getAttribute("HTTP_SHIB_PERSON_SURNAME"); // Multi-valued

                Object mailAttr = request.getAttribute("HTTP_SHIB_INETORGPERSON_MAIL"); // Multi-valued

                Object userclassAttr = request.getAttribute("HTTP_SHIB_EP_UNSCOPEDAFFILIATION"); // Multi-valued

                // Use a configured test username if found, as a shortcut for development deployments.

                if (getConfiguration().getString("testUsername") != null)

                        usernameAttr = getConfiguration().getString("testUsername");

                if (usernameAttr == null) {

                        String authErrorUrl = "authenticationError.jsp";

                        authErrorUrl += "?name=" + (nameAttr==null? "-": nameAttr.toString());

                        authErrorUrl += "&givenname=" + (givennameAttr==null? "-": givennameAttr.toString());

                        authErrorUrl += "&sn=" + (snAttr==null? "-": snAttr.toString());

                        authErrorUrl += "&cn=" + (cnAttr==null? "-": cnAttr.toString());

                        authErrorUrl += "&mail=" + (mailAttr==null? "-": mailAttr.toString());

                        authErrorUrl += "&userclass=" + (userclassAttr==null? "-": userclassAttr.toString());

                        response.sendRedirect(authErrorUrl);

                        return;

                }

                String username = decodeAttribute(usernameAttr);

                String name;

                if (nameAttr != null && !nameAttr.toString().isEmpty())

                        name = decodeAttribute(nameAttr);

                else if (cnAttr != null && !cnAttr.toString().isEmpty()) {

                        name = decodeAttribute(cnAttr);

                        if (name.indexOf(';') != -1)

                                name = name.substring(0, name.indexOf(';'));

                } else if (givennameAttr != null && snAttr != null && !givennameAttr.toString().isEmpty() && !snAttr.toString().isEmpty()) {

                        String givenname = decodeAttribute(givennameAttr);

                        if (givenname.indexOf(';') != -1)

                                givenname = givenname.substring(0, givenname.indexOf(';'));

                        String sn = decodeAttribute(snAttr);

                        if (sn.indexOf(';') != -1)

                                sn = sn.substring(0, sn.indexOf(';'));

                        name = givenname + ' ' + sn;

                } else if (givennameAttr == null && snAttr != null && !snAttr.toString().isEmpty()) {

                        name = decodeAttribute(snAttr);

                        if (name.indexOf(';') != -1)

                                name = name.substring(0, name.indexOf(';'));

                } else

                        name = username;

                String mail = mailAttr != null ? mailAttr.toString() : username;

                if (mail.indexOf(';') != -1)

                        mail = mail.substring(0, mail.indexOf(';'));

                // XXX we are not using the user class currently

                String userclass = userclassAttr != null ? userclassAttr.toString() : "";

                if (userclass.indexOf(';') != -1)

                        userclass = userclass.substring(0, userclass.indexOf(';'));

                try {

                        user = getService().findUser(username);

                        if (user == null)

                                user = getService().createUser(username, name, mail);

                        if (!user.hasAcceptedPolicy()) {

                                String policyUrl = "policy.jsp";

                                if (request.getQueryString() != null)

                                        policyUrl += "?user=" + username + "&" + request.getQueryString();

                                response.sendRedirect(policyUrl);

                                return;

                        }

                        // Update the user name and e-mail if modified.

                        boolean update = false;

                        if (!user.getName().equals(name)) {

                                user.setName(name);

                                update = true;

                        }

                        if (!user.getEmail().equals(mail)) {

                                user.setEmail(mail);

                                update = true;

                        }

                        if (user.getAuthToken() == null)

                                user = getService().updateUserToken(user.getId());

                        // Set WebDAV password to token if it's never been set.

                        if (user.getWebDAVPassword()==null || user.getWebDAVPassword().length()==0) {

                                String tokenEncoded = new String(Base64.encodeBase64(user.getAuthToken()), "US-ASCII");

                                user.setWebDAVPassword(tokenEncoded);

                                update = true;

                        }

                        if (update)

                                getService().updateUser(user);

                } catch (RpcException e) {

                        String error = "An error occurred while communicating with the service";

                        logger.error(error, e);

                        response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, error);

                        return;

                } catch (DuplicateNameException e) {

                        String error = "User with username " + username + " already exists";

                        logger.error(error, e);

                        response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, error);

                        return;

                } catch (ObjectNotFoundException e) {

                        String error = "No username was provided";

                        logger.error(error, e);

                        response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, error);

                        return;

                }

                String tokenEncoded = new String(Base64.encodeBase64(user.getAuthToken()), "US-ASCII");

                String userEncoded = URLEncoder.encode(user.getUsername(), "US-ASCII");

                if (logger.isDebugEnabled())

                        logger.debug("user: "+userEncoded+" token: "+tokenEncoded);

                if (nextUrl != null && !nextUrl.isEmpty()) {

                        URI next;

                        try {

                                next = new URI(nextUrl);

                        } catch (URISyntaxException e) {

                                response.sendError(HttpServletResponse.SC_BAD_REQUEST, e.getMessage());

                                return;

                        }

                        String domain = next.getHost();

                        String path = next.getPath();

                        Cookie cookie = new Cookie(AUTH_COOKIE, userEncoded + COOKIE_SEPARATOR +

                                                tokenEncoded);

                        cookie.setMaxAge(-1);

                        cookie.setDomain(domain);

                        cookie.setPath(path);

                    response.addCookie(cookie);

                    cookie = new Cookie(WEBDAV_COOKIE, user.getWebDAVPassword());

                        cookie.setMaxAge(-1);

                        cookie.setDomain(domain);

                        cookie.setPath(path);

                    response.addCookie(cookie);

                    response.sendRedirect(nextUrl);

                } else if (nonce != null) {

                        nonce = URLEncoder.encode(nonce, "US-ASCII");

                        Nonce n = null;

                        try {

                                if (logger.isDebugEnabled())

                                        logger.debug("user: "+user.getId()+" nonce: "+nonce);

                                n = getService().getNonce(nonce, user.getId());

                        } catch (ObjectNotFoundException e) {

                            PrintWriter out = response.getWriter();

                            out.println("<HTML>");

                            out.println("<HEAD><TITLE>" + getServiceName() + " Authentication</TITLE>" +

                                            "<LINK TYPE='text/css' REL='stylesheet' HREF='gss.css'></HEAD>");

                            out.println("<BODY><CENTER><P>");

                            out.println("The supplied nonce could not be found!");

                            out.println("</CENTER></BODY></HTML>");

                            return;

                        } catch (RpcException e) {

                                String error = "An error occurred while communicating with the service";

                                logger.error(error, e);

                                response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, error);

                                return;

                        }

                        try {

                                getService().activateUserNonce(user.getId(), nonce, n.getNonceExpiryDate());

                        } catch (ObjectNotFoundException e) {

                                String error = "Unable to find user";

                                logger.error(error, e);

                                response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, error);

                                return;

                        } catch (RpcException e) {

                                String error = "An error occurred while communicating with the service";

                                logger.error(error, e);

                                response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, error);

                                return;

                        }

                        try {

                                getService().removeNonce(n.getId());

                        } catch (ObjectNotFoundException e) {

                                logger.info("Nonce already removed!", e);

                        } catch (RpcException e) {

                                logger.warn("Could not remove nonce from data store", e);

                        }

                    PrintWriter out = response.getWriter();

                    out.println("<HTML>");

                    out.println("<HEAD><TITLE>" + getServiceName() + " Authentication</TITLE>" +

                                    "<LINK TYPE='text/css' REL='stylesheet' HREF='gss.css'></HEAD>");

                    out.println("<BODY><CENTER><P>");

                    out.println("You can now close this browser window and return to your application.");

                    out.println("</CENTER></BODY></HTML>");

                } else {

                    PrintWriter out = response.getWriter();

                    out.println("<HTML>");

                    out.println("<HEAD><TITLE>" + getServiceName() + " Authentication</TITLE>" +

                                    "<LINK TYPE='text/css' REL='stylesheet' HREF='gss.css'></HEAD>");

                    out.println("<BODY><CENTER><P>");

                    out.println("Name: " + user.getName() + "<BR>");

                    out.println("E-mail: " + user.getEmail() + "<BR><P>");

                    out.println("Username: " + user.getUsername() + "<BR>");

                    out.println("Athentication token: " + tokenEncoded + "<BR>");

                    out.println("</CENTER></BODY></HTML>");

                }

        }

        /**

         * Decode the request attribute provided by the container to a UTF-8

         * string, since GSS assumes all data to be encoded in UTF-8. The

         * servlet container's encoding can be specified in gss.properties.

         */

        private String decodeAttribute(Object attribute) throws UnsupportedEncodingException {

                return new String(attribute.toString().getBytes(getConfiguration().getString("requestAttributeEncoding")), "UTF-8");

        }

        /**

         * A helper method that converts a byte buffer to a printable list of

         * hexadecimal numbers.

         */

        private String getHexString(byte[] buffer) {

                StringBuilder sb = new StringBuilder();

                Formatter formatter = new Formatter(sb);

                for (int i=0; i<buffer.length; i++)

                        formatter.format("0x%x, ", buffer[i]);

                return sb.toString();

        }

}