Detect DirContextAuthenticationStrategy bean

This commit improves the LDAP auto-configuration to detect if a
DirContextAuthenticationStrategy bean is defined and, if so, associates
it with the auto-configured `LdapContextSource`.

See gh-19328

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/ldap/LdapAutoConfiguration.java

@@ -18,6 +18,7 @@ package org.springframework.boot.autoconfigure.ldap;
 
 import java.util.Collections;
 
+import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -29,6 +30,7 @@ import org.springframework.core.env.Environment;
 import org.springframework.ldap.core.ContextSource;
 import org.springframework.ldap.core.LdapOperations;
 import org.springframework.ldap.core.LdapTemplate;
+import org.springframework.ldap.core.support.DirContextAuthenticationStrategy;
 import org.springframework.ldap.core.support.LdapContextSource;
 
 /**
@@ -45,7 +47,8 @@ public class LdapAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	public LdapContextSource ldapContextSource(LdapProperties properties, Environment environment) {
+	public LdapContextSource ldapContextSource(LdapProperties properties, Environment environment,
+			ObjectProvider<DirContextAuthenticationStrategy> authenticationStrategy) {
 		LdapContextSource source = new LdapContextSource();
 		PropertyMapper propertyMapper = PropertyMapper.get().alwaysApplyingWhenNonNull();
 		propertyMapper.from(properties.getUsername()).to(source::setUserDn);
@@ -55,6 +58,8 @@ public class LdapAutoConfiguration {
 		propertyMapper.from(properties.determineUrls(environment)).to(source::setUrls);
 		propertyMapper.from(properties.getBaseEnvironment()).to(
 				(baseEnvironment) -> source.setBaseEnvironmentProperties(Collections.unmodifiableMap(baseEnvironment)));
+
+		authenticationStrategy.ifUnique(source::setAuthenticationStrategy);
 		return source;
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/ldap/LdapAutoConfigurationTests.java

@@ -16,6 +16,10 @@
 
 package org.springframework.boot.autoconfigure.ldap;
 
+import java.util.Hashtable;
+
+import javax.naming.directory.DirContext;
+
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
@@ -24,9 +28,12 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 import org.springframework.ldap.core.LdapTemplate;
+import org.springframework.ldap.core.support.DirContextAuthenticationStrategy;
 import org.springframework.ldap.core.support.LdapContextSource;
+import org.springframework.ldap.core.support.SimpleDirContextAuthenticationStrategy;
 import org.springframework.ldap.pool2.factory.PoolConfig;
 import org.springframework.ldap.pool2.factory.PooledContextSource;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -90,11 +97,14 @@ class LdapAutoConfigurationTests {
 	@Test
 	void contextSourceWithNoCustomization() {
 		this.contextRunner.run((context) -> {
+			assertThat(context).doesNotHaveBean(DirContextAuthenticationStrategy.class);
 			LdapContextSource contextSource = context.getBean(LdapContextSource.class);
 			assertThat(contextSource.getUserDn()).isEqualTo("");
 			assertThat(contextSource.getPassword()).isEqualTo("");
 			assertThat(contextSource.isAnonymousReadOnly()).isFalse();
 			assertThat(contextSource.getBaseLdapPathAsString()).isEqualTo("");
+			assertThat(ReflectionTestUtils.getField(contextSource, "authenticationStrategy"))
+					.isInstanceOf(SimpleDirContextAuthenticationStrategy.class);
 		});
 	}
 
@@ -113,6 +123,35 @@ class LdapAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void contextSourceWithCustomUniqueDirContextAuthenticationStrategy() {
+		this.contextRunner.withUserConfiguration(CustomDirContextAuthenticationStrategy.class).run((context) -> {
+			assertThat(context).hasSingleBean(DirContextAuthenticationStrategy.class);
+			LdapContextSource contextSource = context.getBean(LdapContextSource.class);
+			assertThat(ReflectionTestUtils.getField(contextSource, "authenticationStrategy"))
+					.isEqualTo(context.getBean(DirContextAuthenticationStrategy.class));
+		});
+	}
+
+	@Test
+	void contextSourceWithCustomNonUniqueDirContextAuthenticationStrategy() {
+		this.contextRunner.withUserConfiguration(CustomDirContextAuthenticationStrategy.class,
+				AnotherCustomDirContextAuthenticationStrategy.class).run((context) -> {
+					assertThat(context).hasBean("customDirContextAuthenticationStrategy")
+							.hasBean("anotherCustomDirContextAuthenticationStrategy");
+					TestDirContextAuthenticationStrategy customDirContextAuthenticationStrategy = context.getBean(
+							"customDirContextAuthenticationStrategy", TestDirContextAuthenticationStrategy.class);
+					TestDirContextAuthenticationStrategy anotherCustomDirContextAuthenticationStrategy = context
+							.getBean("anotherCustomDirContextAuthenticationStrategy",
+									TestDirContextAuthenticationStrategy.class);
+					LdapContextSource contextSource = context.getBean(LdapContextSource.class);
+					assertThat(ReflectionTestUtils.getField(contextSource, "authenticationStrategy"))
+							.isNotEqualTo(customDirContextAuthenticationStrategy)
+							.isNotEqualTo(anotherCustomDirContextAuthenticationStrategy)
+							.isInstanceOf(SimpleDirContextAuthenticationStrategy.class);
+				});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class PooledContextSourceConfig {
 
@@ -126,4 +165,38 @@ class LdapAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class CustomDirContextAuthenticationStrategy {
+
+		@Bean
+		DirContextAuthenticationStrategy customDirContextAuthenticationStrategy() {
+			return new TestDirContextAuthenticationStrategy();
+		}
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class AnotherCustomDirContextAuthenticationStrategy {
+
+		@Bean
+		DirContextAuthenticationStrategy anotherCustomDirContextAuthenticationStrategy() {
+			return new TestDirContextAuthenticationStrategy();
+		}
+
+	}
+
+	static class TestDirContextAuthenticationStrategy implements DirContextAuthenticationStrategy {
+
+		@Override
+		public void setupEnvironment(Hashtable<String, Object> env, String userDn, String password) {
+
+		}
+
+		@Override
+		public DirContext processContextAfterCreation(DirContext ctx, String userDn, String password) {
+			return ctx;
+		}
+
+	}
+
 }