Java tutorial
/** * Licensed to Cloudera, Inc. under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. Cloudera, Inc. 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 * * 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 com.cloudera.alfredo.client; import com.sun.security.auth.module.Krb5LoginModule; import org.apache.commons.codec.binary.Base64; import org.ietf.jgss.GSSContext; import org.ietf.jgss.GSSManager; import org.ietf.jgss.GSSName; import sun.security.jgss.GSSUtil; import javax.security.auth.Subject; import javax.security.auth.login.AppConfigurationEntry; import javax.security.auth.login.Configuration; import javax.security.auth.login.LoginContext; import javax.security.auth.login.LoginException; import java.io.IOException; import java.net.HttpURLConnection; import java.net.URL; import java.security.AccessControlContext; import java.security.AccessController; import java.security.PrivilegedActionException; import java.security.PrivilegedExceptionAction; import java.util.HashMap; import java.util.Map; /** * The <code>KerberosAuthenticator</code> implements the Kerberos SPNEGO authentication sequence. * <p/> * It uses the default principal for the Kerberos cache (normally set via kinit). * <p/> * It falls back to the {@link PseudoAuthenticator} if the HTTP endpoint does not trigger an SPNEGO authentication * sequence. */ public class KerberosAuthenticator implements Authenticator { /** * HTTP header used by the SPNEGO server endpoint during an authentication sequence. */ public static String WWW_AUTHENTICATE = "WWW-Authenticate"; /** * HTTP header used by the SPNEGO client endpoint during an authentication sequence. */ public static String AUTHORIZATION = "Authorization"; /** * HTTP header prefix used by the SPNEGO client/server endpoints during an authentication sequence. */ public static String NEGOTIATE = "Negotiate"; private static final String AUTH_HTTP_METHOD = "OPTIONS"; /* * Defines the Kerberos configuration that will be used to obtain the kerberos principal from the * Kerberos cache. */ private static class KerberosConfiguration extends Configuration { private static final String OS_LOGIN_MODULE_NAME; private static final boolean windows = System.getProperty("os.name").startsWith("Windows"); static { if (windows) { OS_LOGIN_MODULE_NAME = "com.sun.security.auth.module.NTLoginModule"; } else { OS_LOGIN_MODULE_NAME = "com.sun.security.auth.module.UnixLoginModule"; } } private static final AppConfigurationEntry OS_SPECIFIC_LOGIN = new AppConfigurationEntry( OS_LOGIN_MODULE_NAME, AppConfigurationEntry.LoginModuleControlFlag.REQUIRED, new HashMap<String, String>()); private static final Map<String, String> USER_KERBEROS_OPTIONS = new HashMap<String, String>(); static { USER_KERBEROS_OPTIONS.put("doNotPrompt", "true"); USER_KERBEROS_OPTIONS.put("useTicketCache", "true"); USER_KERBEROS_OPTIONS.put("renewTGT", "true"); String ticketCache = System.getenv("KRB5CCNAME"); if (ticketCache != null) { USER_KERBEROS_OPTIONS.put("ticketCache", ticketCache); } } private static final AppConfigurationEntry USER_KERBEROS_LOGIN = new AppConfigurationEntry( Krb5LoginModule.class.getName(), AppConfigurationEntry.LoginModuleControlFlag.OPTIONAL, USER_KERBEROS_OPTIONS); private static final AppConfigurationEntry[] USER_KERBEROS_CONF = new AppConfigurationEntry[] { OS_SPECIFIC_LOGIN, USER_KERBEROS_LOGIN }; @Override public AppConfigurationEntry[] getAppConfigurationEntry(String appName) { return USER_KERBEROS_CONF; } } static { javax.security.auth.login.Configuration.setConfiguration(new KerberosConfiguration()); } private URL url; private HttpURLConnection conn; private Base64 base64; /** * Performs SPNEGO authentication against the specified URL. * <p/> * If a token is given if does a NOP and returns the given token. * <p/> * If no token is given, it will perform the SPNEGO authentication sequency using a * HTTP <code>OPTIONS</code> request. * * @param url the URl to authenticate against. * @param token the authencation token being used for the user. * @throws IOException if an IO error occurred. * @throws AuthenticationException if an authentication error occurred. */ @Override public void authenticate(URL url, AuthenticatedURL.Token token) throws IOException, AuthenticationException { if (!token.isSet()) { this.url = url; base64 = new Base64(0); conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod(AUTH_HTTP_METHOD); conn.connect(); if (isNegotiate()) { doSpnegoSequence(token); } else { getFallBackAuthenticator().authenticate(url, token); } } } /** * If the specified URL does not support SPNEGO authentication, a fallback {@link Authenticator} wil be used. * <p/> * This implementation returns a {@link PseudoAuthenticator}. * * @return the fallback {@link Authenticator}. */ protected Authenticator getFallBackAuthenticator() { return new PseudoAuthenticator(); } /* * Indicates if the response is starting a SPNEGO negotiation. */ private boolean isNegotiate() throws IOException { boolean negotiate = false; if (conn.getResponseCode() == HttpURLConnection.HTTP_UNAUTHORIZED) { String authHeader = conn.getHeaderField(WWW_AUTHENTICATE); negotiate = authHeader != null && authHeader.trim().startsWith(NEGOTIATE); } return negotiate; } /** * Implements the SPNEGO authentication sequence interaction using the current default principal * in the Kerberos cache (normally set via kinit). * * @param token the authencation token being used for the user. * @throws IOException if an IO error occurred. * @throws AuthenticationException if an authentication error occurred. */ private void doSpnegoSequence(AuthenticatedURL.Token token) throws IOException, AuthenticationException { try { AccessControlContext context = AccessController.getContext(); Subject subject = Subject.getSubject(context); if (subject == null) { subject = new Subject(); LoginContext login = new LoginContext("", subject); login.login(); } Subject.doAs(subject, new PrivilegedExceptionAction<Void>() { @Override public Void run() throws Exception { GSSContext gssContext = null; try { GSSManager gssManager = GSSManager.getInstance(); String servicePrincipal = "HTTP/" + KerberosAuthenticator.this.url.getHost(); GSSName serviceName = gssManager.createName(servicePrincipal, GSSUtil.NT_GSS_KRB5_PRINCIPAL); gssContext = gssManager.createContext(serviceName, GSSUtil.GSS_KRB5_MECH_OID, null, GSSContext.DEFAULT_LIFETIME); gssContext.requestCredDeleg(true); gssContext.requestMutualAuth(true); byte[] inToken = new byte[0]; byte[] outToken; boolean established = false; // Loop while the context is still not established while (!established) { outToken = gssContext.initSecContext(inToken, 0, inToken.length); if (outToken != null) { sendToken(outToken); } if (!gssContext.isEstablished()) { inToken = readToken(); } else { established = true; } } } finally { if (gssContext != null) { gssContext.dispose(); } } return null; } }); } catch (PrivilegedActionException ex) { throw new AuthenticationException(ex.getException()); } catch (LoginException ex) { throw new AuthenticationException(ex); } AuthenticatedURL.extractToken(conn, token); } /* * Sends the Kerberos token to the server. */ private void sendToken(byte[] outToken) throws IOException, AuthenticationException { String token = base64.encodeToString(outToken); conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod(AUTH_HTTP_METHOD); conn.setRequestProperty(AUTHORIZATION, NEGOTIATE + " " + token); conn.connect(); } /* * retrieves the Kerberos token returned by the server. */ private byte[] readToken() throws IOException, AuthenticationException { int status = conn.getResponseCode(); if (status == HttpURLConnection.HTTP_OK || status == HttpURLConnection.HTTP_UNAUTHORIZED) { String authHeader = conn.getHeaderField(WWW_AUTHENTICATE); if (authHeader == null || !authHeader.trim().startsWith(NEGOTIATE)) { throw new AuthenticationException( "Invalid SPNEGO sequence, '" + WWW_AUTHENTICATE + "' header incorrect: " + authHeader); } String negotiation = authHeader.trim().substring((NEGOTIATE + " ").length()).trim(); return base64.decode(negotiation); } throw new AuthenticationException("Invalid SPNEGO sequence, status code: " + status); } }