Improve invalid Content-Type handling in WebFlux

Closes gh-29565

Author: rstoyanchev

spring-web/src/main/java/org/springframework/http/HttpHeaders.java

@@ -984,7 +984,8 @@ public void setContentType(@Nullable MediaType mediaType) {
 	/**
 	 * Return the {@linkplain MediaType media type} of the body, as specified
 	 * by the {@code Content-Type} header.
-	 * <p>Returns {@code null} when the content-type is unknown.
+	 * <p>Returns {@code null} when the {@code Content-Type} header is not set.
+	 * @throws InvalidMediaTypeException if the media type value cannot be parsed
 	 */
 	@Nullable
 	public MediaType getContentType() {

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

@@ -35,8 +35,10 @@
 import org.springframework.core.codec.Hints;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.InvalidMediaTypeException;
 import org.springframework.http.MediaType;
 import org.springframework.http.codec.HttpMessageReader;
 import org.springframework.http.server.reactive.ServerHttpRequest;
@@ -146,7 +148,16 @@ protected Mono<Object> readBody(MethodParameter bodyParam, @Nullable MethodParam
 		ServerHttpRequest request = exchange.getRequest();
 		ServerHttpResponse response = exchange.getResponse();
 
-		MediaType contentType = request.getHeaders().getContentType();
+		MediaType contentType;
+		HttpHeaders headers = request.getHeaders();
+		try {
+			contentType = headers.getContentType();
+		}
+		catch (InvalidMediaTypeException ex) {
+			throw new UnsupportedMediaTypeStatusException(
+					"Can't parse Content-Type [" + headers.getFirst("Content-Type") + "]: " + ex.getMessage());
+		}
+
 		MediaType mediaType = (contentType != null ? contentType : MediaType.APPLICATION_OCTET_STREAM);
 		Object[] hints = extractValidationHints(bodyParam);
 

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

@@ -41,12 +41,14 @@
 import org.springframework.web.reactive.BindingContext;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.ServerWebInputException;
+import org.springframework.web.server.UnsupportedMediaTypeStatusException;
 import org.springframework.web.testfixture.http.server.reactive.MockServerHttpRequest;
 import org.springframework.web.testfixture.method.ResolvableMethod;
 import org.springframework.web.testfixture.server.MockServerWebExchange;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.springframework.web.testfixture.method.MvcAnnotationPredicates.requestBody;
 
 /**
@@ -214,14 +216,26 @@ public void emptyBodyWithCompletableFuture() {
 		});
 	}
 
+	@Test // gh-29565
+	public void invalidContentType() {
+		MethodParameter parameter = this.testMethod.annot(requestBody()).arg(String.class);
+
+		ServerWebExchange exchange = MockServerWebExchange.from(
+				MockServerHttpRequest.post("/path").header("Content-Type", "invalid").build());
+
+		assertThatThrownBy(() -> this.resolver.readBody(parameter, true, new BindingContext(), exchange))
+				.isInstanceOf(UnsupportedMediaTypeStatusException.class);
+	}
+
 	@SuppressWarnings("unchecked")
 	private <T> T resolveValue(MethodParameter param, String body) {
 		ServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.post("/path").body(body));
 		Mono<Object> result = this.resolver.readBody(param, true, new BindingContext(), exchange);
 		Object value = result.block(Duration.ofSeconds(5));
 
 		assertThat(value).isNotNull();
-		assertThat(param.getParameterType().isAssignableFrom(value.getClass())).as("Unexpected return value type: " + value).isTrue();
+		assertThat(param.getParameterType().isAssignableFrom(value.getClass()))
+				.as("Unexpected return value type: " + value).isTrue();
 
 		//no inspection unchecked
 		return (T) value;
@@ -234,7 +248,8 @@ private <T> T resolveValueWithEmptyBody(MethodParameter param) {
 		Object value = result.block(Duration.ofSeconds(5));
 
 		if (value != null) {
-			assertThat(param.getParameterType().isAssignableFrom(value.getClass())).as("Unexpected parameter type: " + value).isTrue();
+			assertThat(param.getParameterType().isAssignableFrom(value.getClass()))
+					.as("Unexpected parameter type: " + value).isTrue();
 		}
 
 		//no inspection unchecked