1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.shiro.authc.pam;
20
21 import org.apache.shiro.authc.AuthenticationException;
22 import org.apache.shiro.authc.AuthenticationInfo;
23 import org.apache.shiro.authc.AuthenticationToken;
24 import org.apache.shiro.realm.Realm;
25 import org.apache.shiro.subject.PrincipalCollection;
26
27 import java.util.Collection;
28
29 /**
30 * {@link AuthenticationStrategy} implementation that only accepts the account data from
31 * the first successfully consulted Realm and ignores all subsequent realms. This is slightly
32 * different behavior than {@link AtLeastOneSuccessfulStrategy}, so please review both to see
33 * which one meets your needs better.
34 *
35 * @see AtLeastOneSuccessfulStrategy AtLeastOneSuccessfulAuthenticationStrategy
36 * @since 0.9
37 */
38 public class FirstSuccessfulStrategy extends AbstractAuthenticationStrategy {
39
40 /**
41 * Returns {@code null} immediately, relying on this class's {@link #merge merge} implementation to return
42 * only the first {@code info} object it encounters, ignoring all subsequent ones.
43 */
44 public AuthenticationInfo beforeAllAttempts(Collection<? extends Realm> realms, AuthenticationToken token) throws AuthenticationException {
45 return null;
46 }
47
48 private static boolean isEmpty(PrincipalCollection pc) {
49 return pc == null || pc.isEmpty();
50 }
51
52 /**
53 * Returns the specified {@code aggregate} instance if is non null and valid (that is, has principals and they are
54 * not empty) immediately, or, if it is null or not valid, the {@code info} argument is returned instead.
55 * <p/>
56 * This logic ensures that the first valid info encountered is the one retained and all subsequent ones are ignored,
57 * since this strategy mandates that only the info from the first successfully authenticated realm be used.
58 */
59 protected AuthenticationInfo merge(AuthenticationInfo info, AuthenticationInfo aggregate) {
60 if (aggregate != null && !isEmpty(aggregate.getPrincipals())) {
61 return aggregate;
62 }
63 return info != null ? info : aggregate;
64 }
65 }