Handle DataBufferLimitException as HTTP 413 responses

Prior to this commit, `DataBufferLimitException` would be thrown by
codecs when the request body was too large for the configured buffer
limit. This exception would not be handled by the web infrastructure and
would result in an HTTP 500 server error.

This commit introduces a new `PayloadTooLargeException` type that will
result in an HTTP 413 "Payload too large" response status.

Closes spring-projectsgh-32558

spring-web/src/main/java/org/springframework/web/server/PayloadTooLargeException.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2002-2024 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.web.server;
+
+
+import org.springframework.http.HttpStatus;
+import org.springframework.lang.Nullable;
+
+/**
+ * Exception for errors that fit response status 413 (payload too large) for use in
+ * Spring Web applications.
+ *
+ * @author Kim Bosung
+ * @since 6.2
+ */
+@SuppressWarnings("serial")
+public class PayloadTooLargeException extends ResponseStatusException {
+
+	public PayloadTooLargeException(@Nullable Throwable cause) {
+		super(HttpStatus.PAYLOAD_TOO_LARGE, null, cause);
+	}
+
+}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/AbstractMessageReaderArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -34,6 +34,7 @@
 import org.springframework.core.codec.DecodingException;
 import org.springframework.core.codec.Hints;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.core.io.buffer.DataBufferLimitException;
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -51,6 +52,7 @@
 import org.springframework.web.bind.support.WebExchangeDataBinder;
 import org.springframework.web.reactive.BindingContext;
 import org.springframework.web.reactive.result.method.HandlerMethodArgumentResolverSupport;
+import org.springframework.web.server.PayloadTooLargeException;
 import org.springframework.web.server.ResponseStatusException;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.ServerWebInputException;
@@ -218,7 +220,7 @@ protected Mono<Object> readBody(MethodParameter bodyParam, @Nullable MethodParam
 		if (contentType == null && SUPPORTED_METHODS.contains(method)) {
 			Flux<DataBuffer> body = request.getBody().doOnNext(buffer -> {
 				DataBufferUtils.release(buffer);
-				// Body not empty, back toy 415..
+				// Body not empty, back to HTTP 415
 				throw new UnsupportedMediaTypeStatusException(
 						mediaType, getSupportedMediaTypes(elementType), elementType);
 			});
@@ -233,8 +235,13 @@ protected Mono<Object> readBody(MethodParameter bodyParam, @Nullable MethodParam
 	}
 
 	private Throwable handleReadError(MethodParameter parameter, Throwable ex) {
-		return (ex instanceof DecodingException ?
-				new ServerWebInputException("Failed to read HTTP message", parameter, ex) : ex);
+		if (ex instanceof DataBufferLimitException) {
+			return new PayloadTooLargeException(ex);
+		}
+		if (ex instanceof DecodingException) {
+			return new ServerWebInputException("Failed to read HTTP message", parameter, ex);
+		}
+		return ex;
 	}
 
 	private ServerWebInputException handleMissingBody(MethodParameter parameter) {

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MessageReaderArgumentResolverTests.java

@@ -52,6 +52,7 @@
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.method.HandlerMethod;
 import org.springframework.web.reactive.BindingContext;
+import org.springframework.web.server.PayloadTooLargeException;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.ServerWebInputException;
 import org.springframework.web.server.UnsupportedMediaTypeStatusException;
@@ -112,6 +113,24 @@ public void emptyBody() {
 		StepVerifier.create(result).expectError(ServerWebInputException.class).verify();
 	}
 
+	@Test @SuppressWarnings("unchecked")
+	public void tooLargeBody() {
+		StringBuilder bodyBuilder = new StringBuilder();
+		while (bodyBuilder.toString().getBytes().length < 256 * 1024) {
+			bodyBuilder.append("The default maximum input length is 256kb.");
+		}
+		String body = "{\"bar\":\"BARBAR\",\"foo\":\"" + bodyBuilder + "\"}";
+
+		MockServerHttpRequest request = post("/path").contentType(MediaType.APPLICATION_JSON).body(body);
+		ServerWebExchange exchange = MockServerWebExchange.from(request);
+		ResolvableType type = forClassWithGenerics(Mono.class, TestBean.class);
+		MethodParameter param = this.testMethod.arg(type);
+		Mono<TestBean> result = (Mono<TestBean>) this.resolver.readBody(
+				param, true, this.bindingContext, exchange).block();
+
+		StepVerifier.create(result).expectError(PayloadTooLargeException.class).verify();
+	}
+
 	@Test
 	void monoTestBean() {
 		String body = "{\"bar\":\"BARBAR\",\"foo\":\"FOOFOO\"}";