Add Reactive Messaging AuthenticationPrincipalArgumentResolver

Fixes gh-7363

Author: rwinch

messaging/spring-security-messaging.gradle

@@ -10,6 +10,7 @@ dependencies {
 
 	optional project(':spring-security-web')
 	optional 'org.springframework:spring-websocket'
+	optional 'io.projectreactor:reactor-core'
 	optional 'javax.servlet:javax.servlet-api'
 
 	testCompile project(path: ':spring-security-core', configuration: 'tests')

messaging/src/main/java/org/springframework/security/messaging/handler/invocation/reactive/AuthenticationPrincipalArgumentResolver.java

@@ -0,0 +1,210 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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 org.springframework.security.messaging.handler.invocation.reactive;
+
+import org.reactivestreams.Publisher;
+import org.springframework.core.MethodParameter;
+import org.springframework.core.ReactiveAdapter;
+import org.springframework.core.ReactiveAdapterRegistry;
+import org.springframework.core.ResolvableType;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.expression.BeanResolver;
+import org.springframework.expression.Expression;
+import org.springframework.expression.ExpressionParser;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.handler.invocation.reactive.HandlerMethodArgumentResolver;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.security.core.context.ReactiveSecurityContextHolder;
+import org.springframework.security.core.context.SecurityContext;
+import org.springframework.stereotype.Controller;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+import reactor.core.publisher.Mono;
+
+import java.lang.annotation.Annotation;
+
+/**
+ * Allows resolving the {@link Authentication#getPrincipal()} using the
+ * {@link AuthenticationPrincipal} annotation. For example, the following
+ * {@link Controller}:
+ *
+ * <pre>
+ * &#64;Controller
+ * public class MyController {
+ *     &#64;MessageMapping("/im")
+ *     public void im(@AuthenticationPrincipal CustomUser customUser) {
+ *         // do something with CustomUser
+ *     }
+ * }
+ * </pre>
+ *
+ * <p>
+ * Will resolve the CustomUser argument using {@link Authentication#getPrincipal()} from
+ * the {@link ReactiveSecurityContextHolder}. If the {@link Authentication} or
+ * {@link Authentication#getPrincipal()} is null, it will return null. If the types do not
+ * match, null will be returned unless
+ * {@link AuthenticationPrincipal#errorOnInvalidType()} is true in which case a
+ * {@link ClassCastException} will be thrown.
+ *
+ * <p>
+ * Alternatively, users can create a custom meta annotation as shown below:
+ *
+ * <pre>
+ * &#064;Target({ ElementType.PARAMETER })
+ * &#064;Retention(RetentionPolicy.RUNTIME)
+ * &#064;AuthenticationPrincipal
+ * public @interface CurrentUser {
+ * }
+ * </pre>
+ *
+ * <p>
+ * The custom annotation can then be used instead. For example:
+ *
+ * <pre>
+ * &#64;Controller
+ * public class MyController {
+ *     &#64;MessageMapping("/im")
+ *     public void im(@CurrentUser CustomUser customUser) {
+ *         // do something with CustomUser
+ *     }
+ * }
+ * </pre>
+ * @author Rob Winch
+ * @since 5.2
+ */
+public class AuthenticationPrincipalArgumentResolver
+		implements HandlerMethodArgumentResolver {
+
+	private ExpressionParser parser = new SpelExpressionParser();
+
+	private BeanResolver beanResolver;
+
+	private ReactiveAdapterRegistry adapterRegistry = ReactiveAdapterRegistry
+			.getSharedInstance();
+
+	/**
+	 * Sets the {@link BeanResolver} to be used on the expressions
+	 * @param beanResolver the {@link BeanResolver} to use
+	 */
+	public void setBeanResolver(BeanResolver beanResolver) {
+		this.beanResolver = beanResolver;
+	}
+
+	/**
+	 * Sets the {@link ReactiveAdapterRegistry} to be used.
+	 * @param adapterRegistry the {@link ReactiveAdapterRegistry} to use. Cannot be null. Default is
+	 * {@link ReactiveAdapterRegistry#getSharedInstance()}
+	 */
+	public void setAdapterRegistry(ReactiveAdapterRegistry adapterRegistry) {
+		Assert.notNull(adapterRegistry, "adapterRegistry cannot be null");
+		this.adapterRegistry = adapterRegistry;
+	}
+
+	@Override
+	public boolean supportsParameter(MethodParameter parameter) {
+		return findMethodAnnotation(AuthenticationPrincipal.class, parameter) != null;
+	}
+
+	public Mono<Object> resolveArgument(MethodParameter parameter, Message<?> message) {
+		ReactiveAdapter adapter = this.adapterRegistry
+				.getAdapter(parameter.getParameterType());
+		return ReactiveSecurityContextHolder.getContext()
+				.map(SecurityContext::getAuthentication).flatMap(a -> {
+					Object p = resolvePrincipal(parameter, a.getPrincipal());
+					Mono<Object> principal = Mono.justOrEmpty(p);
+					return adapter == null ?
+							principal :
+							Mono.just(adapter.fromPublisher(principal));
+				});
+	}
+
+	private Object resolvePrincipal(MethodParameter parameter, Object principal) {
+		AuthenticationPrincipal authPrincipal = findMethodAnnotation(
+				AuthenticationPrincipal.class, parameter);
+
+		String expressionToParse = authPrincipal.expression();
+		if (StringUtils.hasLength(expressionToParse)) {
+			StandardEvaluationContext context = new StandardEvaluationContext();
+			context.setRootObject(principal);
+			context.setVariable("this", principal);
+			context.setBeanResolver(this.beanResolver);
+
+			Expression expression = this.parser.parseExpression(expressionToParse);
+			principal = expression.getValue(context);
+		}
+
+		if (isInvalidType(parameter, principal)) {
+
+			if (authPrincipal.errorOnInvalidType()) {
+				throw new ClassCastException(
+						principal + " is not assignable to " + parameter
+								.getParameterType());
+			}
+			else {
+				return null;
+			}
+		}
+
+		return principal;
+	}
+
+	private boolean isInvalidType(MethodParameter parameter, Object principal) {
+		if (principal == null) {
+			return false;
+		}
+		Class<?> typeToCheck = parameter.getParameterType();
+		boolean isParameterPublisher = Publisher.class
+				.isAssignableFrom(parameter.getParameterType());
+		if (isParameterPublisher) {
+			ResolvableType resolvableType = ResolvableType.forMethodParameter(parameter);
+			Class<?> genericType = resolvableType.resolveGeneric(0);
+			if (genericType == null) {
+				return false;
+			}
+			typeToCheck = genericType;
+		}
+		return !typeToCheck.isAssignableFrom(principal.getClass());
+	}
+
+	/**
+	 * Obtains the specified {@link Annotation} on the specified {@link MethodParameter}.
+	 *
+	 * @param annotationClass the class of the {@link Annotation} to find on the
+	 *                        {@link MethodParameter}
+	 * @param parameter       the {@link MethodParameter} to search for an {@link Annotation}
+	 * @return the {@link Annotation} that was found or null.
+	 */
+	private <T extends Annotation> T findMethodAnnotation(Class<T> annotationClass,
+			MethodParameter parameter) {
+		T annotation = parameter.getParameterAnnotation(annotationClass);
+		if (annotation != null) {
+			return annotation;
+		}
+		Annotation[] annotationsToSearch = parameter.getParameterAnnotations();
+		for (Annotation toSearch : annotationsToSearch) {
+			annotation = AnnotationUtils
+					.findAnnotation(toSearch.annotationType(), annotationClass);
+			if (annotation != null) {
+				return annotation;
+			}
+		}
+		return null;
+	}
+}