Add AuthenticationPrincipalArgumentResolver

Closes gh-272

Author: rwinch

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/AnnotatedControllerConfigurer.java

@@ -36,6 +36,8 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.dataloader.DataLoader;
+import org.springframework.context.expression.BeanFactoryResolver;
+import org.springframework.expression.BeanResolver;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
@@ -166,6 +168,8 @@ public void afterPropertiesSet() {
 		this.argumentResolvers.addResolver(new DataLoaderMethodArgumentResolver());
 		if (springSecurityPresent) {
 			this.argumentResolvers.addResolver(new PrincipalMethodArgumentResolver());
+			BeanResolver beanResolver = new BeanFactoryResolver(obtainApplicationContext());
+			this.argumentResolvers.addResolver(new AuthenticationPrincipalArgumentResolver(beanResolver));
 		}
 		if (KotlinDetector.isKotlinPresent()) {
 			this.argumentResolvers.addResolver(new ContinuationHandlerMethodArgumentResolver());

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/AuthenticationPrincipalArgumentResolver.java

@@ -0,0 +1,153 @@
+/*
+ * Copyright 2002-2022 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.graphql.data.method.annotation.support;
+
+import graphql.schema.DataFetchingEnvironment;
+import org.reactivestreams.Publisher;
+import org.springframework.core.MethodParameter;
+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.graphql.data.method.HandlerMethodArgumentResolver;
+import org.springframework.lang.Nullable;
+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.security.core.context.SecurityContextHolder;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
+import reactor.core.publisher.Mono;
+
+import java.lang.annotation.Annotation;
+
+/**
+ * Resolver to obtain {@link Authentication#getPrincipal()} from Spring Security context via
+ * {@link SecurityContext#getAuthentication()} for parameters annotated with {@link AuthenticationPrincipal}.
+ *
+ * <p>The resolver checks both ThreadLocal context via {@link SecurityContextHolder}
+ * for Spring MVC applications, and {@link ReactiveSecurityContextHolder} for
+ * Spring WebFlux applications.
+ *
+ * @author Rob Winch
+ * @since 1.0.0
+ */
+public class AuthenticationPrincipalArgumentResolver implements HandlerMethodArgumentResolver {
+
+	private ExpressionParser parser = new SpelExpressionParser();
+
+	private final BeanResolver beanResolver;
+
+	/**
+	 * Creates a new instance.
+	 * @param beanResolver the {@link BeanResolver} used for resolving beans in SpEL expressions. Cannot be null.
+	 */
+	public AuthenticationPrincipalArgumentResolver(BeanResolver beanResolver) {
+		Assert.notNull(beanResolver, "BeanResolver is required");
+		this.beanResolver = beanResolver;
+	}
+
+	@Override
+	public boolean supportsParameter(MethodParameter parameter) {
+		return findMethodAnnotation(AuthenticationPrincipal.class, parameter) != null;
+	}
+
+	@Override
+	public Object resolveArgument(MethodParameter parameter, DataFetchingEnvironment environment) throws Exception {
+		return getCurrentAuthentication().map(Authentication::getPrincipal)
+				.flatMap((principal) -> Mono.justOrEmpty(resolvePrincipal(parameter, principal)))
+				.transform((argument) -> {
+					boolean isParameterPublisher = isParameterMonoAssignable(parameter);
+					return  isParameterPublisher ? Mono.just(argument) : argument;
+				});
+	}
+
+	private Mono<Authentication> getCurrentAuthentication() {
+		SecurityContext securityContext = SecurityContextHolder.getContext();
+		return Mono.justOrEmpty(securityContext.getAuthentication())
+				.switchIfEmpty(ReactiveSecurityContextHolder.getContext().map(SecurityContext::getAuthentication));
+	}
+
+	@Nullable
+	private Object resolvePrincipal(MethodParameter parameter, Object principal) {
+		AuthenticationPrincipal annotation = findMethodAnnotation(AuthenticationPrincipal.class, parameter);
+		String expressionToParse = annotation.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 (annotation.errorOnInvalidType()) {
+				throw new ClassCastException(principal + " is not assignable to " + parameter.getParameterType());
+			}
+			return null;
+		}
+		return principal;
+	}
+
+	private boolean isInvalidType(MethodParameter parameter, @Nullable Object principal) {
+		if (principal == null) {
+			return false;
+		}
+		Class<?> typeToCheck = parameter.getParameterType();
+		if (isParameterMonoAssignable(parameter)) {
+			ResolvableType resolvableType = ResolvableType.forMethodParameter(parameter);
+			Class<?> genericType = resolvableType.resolveGeneric(0);
+			if (genericType == null) {
+				return false;
+			}
+			typeToCheck = genericType;
+		}
+		return !ClassUtils.isAssignable(typeToCheck, principal.getClass());
+	}
+
+	private boolean isParameterMonoAssignable(MethodParameter parameter) {
+		return Publisher.class.equals(parameter.getParameterType()) ||
+				Mono.class.equals(parameter.getParameterType());
+	}
+
+	/**
+	 * 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.
+	 */
+	@Nullable
+	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;
+	}
+}