Honour SSL key alias when using Netty

See gh-19197

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/SslServerCustomizer.java

@@ -16,12 +16,27 @@
 
 package org.springframework.boot.web.embedded.netty;
 
+import java.net.Socket;
 import java.net.URL;
+import java.security.InvalidAlgorithmParameterException;
 import java.security.KeyStore;
+import java.security.KeyStoreException;
+import java.security.NoSuchAlgorithmException;
+import java.security.Principal;
+import java.security.PrivateKey;
+import java.security.Provider;
+import java.security.UnrecoverableKeyException;
+import java.security.cert.X509Certificate;
 import java.util.Arrays;
+import java.util.stream.Collectors;
 
+import javax.net.ssl.KeyManager;
 import javax.net.ssl.KeyManagerFactory;
+import javax.net.ssl.KeyManagerFactorySpi;
+import javax.net.ssl.ManagerFactoryParameters;
+import javax.net.ssl.SSLEngine;
 import javax.net.ssl.TrustManagerFactory;
+import javax.net.ssl.X509ExtendedKeyManager;
 
 import io.netty.handler.ssl.ClientAuth;
 import io.netty.handler.ssl.SslContextBuilder;
@@ -92,8 +107,10 @@ public class SslServerCustomizer implements NettyServerCustomizer {
 	protected KeyManagerFactory getKeyManagerFactory(Ssl ssl, SslStoreProvider sslStoreProvider) {
 		try {
 			KeyStore keyStore = getKeyStore(ssl, sslStoreProvider);
-			KeyManagerFactory keyManagerFactory = KeyManagerFactory
-					.getInstance(KeyManagerFactory.getDefaultAlgorithm());
+			KeyManagerFactory keyManagerFactory = (ssl.getKeyAlias() == null)
+					? KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm())
+					: ConfigurableAliasKeyManagerFactory.instance(ssl.getKeyAlias(),
+							KeyManagerFactory.getDefaultAlgorithm());
 			char[] keyPassword = (ssl.getKeyPassword() != null) ? ssl.getKeyPassword().toCharArray() : null;
 			if (keyPassword == null && ssl.getKeyStorePassword() != null) {
 				keyPassword = ssl.getKeyStorePassword().toCharArray();
@@ -161,4 +178,120 @@ public class SslServerCustomizer implements NettyServerCustomizer {
 
 	}
 
+	/**
+	 * A {@link KeyManagerFactory} that allows a configurable key alias to be used. Due to
+	 * the fact that the actual calls to retrieve the key by alias are done at request
+	 * time the approach is to wrap the actual key managers with a
+	 * {@link ConfigurableAliasKeyManager}. The actual SPI has to be wrapped as well due
+	 * to the fact that {@link KeyManagerFactory#getKeyManagers()} is final.
+	 */
+	private static class ConfigurableAliasKeyManagerFactory extends KeyManagerFactory {
+
+		static final ConfigurableAliasKeyManagerFactory instance(String alias, String algorithm)
+				throws NoSuchAlgorithmException {
+			KeyManagerFactory originalFactory = KeyManagerFactory.getInstance(algorithm);
+			ConfigurableAliasKeyManagerFactorySpi spi = new ConfigurableAliasKeyManagerFactorySpi(originalFactory,
+					alias);
+			return new ConfigurableAliasKeyManagerFactory(spi, originalFactory.getProvider(), algorithm);
+		}
+
+		ConfigurableAliasKeyManagerFactory(ConfigurableAliasKeyManagerFactorySpi spi, Provider provider,
+				String algorithm) {
+			super(spi, provider, algorithm);
+		}
+
+	}
+
+	private static class ConfigurableAliasKeyManagerFactorySpi extends KeyManagerFactorySpi {
+
+		private KeyManagerFactory originalFactory;
+
+		private String alias;
+
+		ConfigurableAliasKeyManagerFactorySpi(KeyManagerFactory originalFactory, String alias) {
+			this.originalFactory = originalFactory;
+			this.alias = alias;
+		}
+
+		@Override
+		protected void engineInit(KeyStore keyStore, char[] chars)
+				throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException {
+			this.originalFactory.init(keyStore, chars);
+		}
+
+		@Override
+		protected void engineInit(ManagerFactoryParameters managerFactoryParameters)
+				throws InvalidAlgorithmParameterException {
+			throw new InvalidAlgorithmParameterException("Unsupported ManagerFactoryParameters");
+		}
+
+		@Override
+		protected KeyManager[] engineGetKeyManagers() {
+			return Arrays.stream(this.originalFactory.getKeyManagers()).filter(X509ExtendedKeyManager.class::isInstance)
+					.map(X509ExtendedKeyManager.class::cast).map(this::wrapKeyManager).collect(Collectors.toList())
+					.toArray(new KeyManager[0]);
+		}
+
+		private ConfigurableAliasKeyManager wrapKeyManager(X509ExtendedKeyManager km) {
+			return new ConfigurableAliasKeyManager(km, this.alias);
+		}
+
+	}
+
+	private static class ConfigurableAliasKeyManager extends X509ExtendedKeyManager {
+
+		private final X509ExtendedKeyManager keyManager;
+
+		private final String alias;
+
+		ConfigurableAliasKeyManager(X509ExtendedKeyManager keyManager, String alias) {
+			this.keyManager = keyManager;
+			this.alias = alias;
+		}
+
+		@Override
+		public String chooseEngineClientAlias(String[] strings, Principal[] principals, SSLEngine sslEngine) {
+			return this.keyManager.chooseEngineClientAlias(strings, principals, sslEngine);
+		}
+
+		@Override
+		public String chooseEngineServerAlias(String s, Principal[] principals, SSLEngine sslEngine) {
+			if (this.alias == null) {
+				return this.keyManager.chooseEngineServerAlias(s, principals, sslEngine);
+			}
+			return this.alias;
+		}
+
+		@Override
+		public String chooseClientAlias(String[] keyType, Principal[] issuers, Socket socket) {
+			return this.keyManager.chooseClientAlias(keyType, issuers, socket);
+		}
+
+		@Override
+		public String chooseServerAlias(String keyType, Principal[] issuers, Socket socket) {
+			return this.keyManager.chooseServerAlias(keyType, issuers, socket);
+		}
+
+		@Override
+		public X509Certificate[] getCertificateChain(String alias) {
+			return this.keyManager.getCertificateChain(alias);
+		}
+
+		@Override
+		public String[] getClientAliases(String keyType, Principal[] issuers) {
+			return this.keyManager.getClientAliases(keyType, issuers);
+		}
+
+		@Override
+		public PrivateKey getPrivateKey(String alias) {
+			return this.keyManager.getPrivateKey(alias);
+		}
+
+		@Override
+		public String[] getServerAliases(String keyType, Principal[] issuers) {
+			return this.keyManager.getServerAliases(keyType, issuers);
+		}
+
+	}
+
 }

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/netty/NettyReactiveWebServerFactoryTests.java

@@ -16,15 +16,25 @@
 
 package org.springframework.boot.web.embedded.netty;
 
+import java.time.Duration;
 import java.util.Arrays;
 
+import javax.net.ssl.SSLHandshakeException;
+
 import org.junit.Test;
 import org.mockito.InOrder;
+import reactor.core.publisher.Mono;
 import reactor.netty.http.server.HttpServer;
+import reactor.test.StepVerifier;
 
 import org.springframework.boot.web.reactive.server.AbstractReactiveWebServerFactory;
 import org.springframework.boot.web.reactive.server.AbstractReactiveWebServerFactoryTests;
 import org.springframework.boot.web.server.PortInUseException;
+import org.springframework.boot.web.server.Ssl;
+import org.springframework.http.MediaType;
+import org.springframework.http.client.reactive.ReactorClientHttpConnector;
+import org.springframework.web.reactive.function.BodyInserters;
+import org.springframework.web.reactive.function.client.WebClient;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -83,4 +93,38 @@ public class NettyReactiveWebServerFactoryTests extends AbstractReactiveWebServe
 		assertForwardHeaderIsUsed(factory);
 	}
 
+	@Test
+	public void testSslWithValidAlias() {
+		Mono<String> result = testSslWithAlias("test-alias");
+		StepVerifier.setDefaultTimeout(Duration.ofSeconds(30));
+		StepVerifier.create(result).expectNext("Hello World").verifyComplete();
+	}
+
+	@Test
+	public void testSslWithInvalidAlias() {
+		Mono<String> result = testSslWithAlias("test-alias-bad");
+		StepVerifier.setDefaultTimeout(Duration.ofSeconds(30));
+		StepVerifier.create(result).expectErrorMatches((throwable) -> throwable instanceof SSLHandshakeException
+				&& throwable.getMessage().contains("HANDSHAKE_FAILURE")).verify();
+	}
+
+	protected Mono<String> testSslWithAlias(String alias) {
+		String keyStore = "classpath:test.jks";
+		String keyPassword = "password";
+		NettyReactiveWebServerFactory factory = getFactory();
+		Ssl ssl = new Ssl();
+		ssl.setKeyStore(keyStore);
+		ssl.setKeyPassword(keyPassword);
+		ssl.setKeyAlias(alias);
+		factory.setSsl(ssl);
+		this.webServer = factory.getWebServer(new EchoHandler());
+		this.webServer.start();
+		ReactorClientHttpConnector connector = buildTrustAllSslConnector();
+		WebClient client = WebClient.builder().baseUrl("https://localhost:" + this.webServer.getPort())
+				.clientConnector(connector).build();
+		return client.post().uri("/test").contentType(MediaType.TEXT_PLAIN)
+				.body(BodyInserters.fromObject("Hello World")).exchange()
+				.flatMap((response) -> response.bodyToMono(String.class));
+	}
+
 }