Merge pull request #36766 from NersesAM

* pr/36766:
  Polish "Set max request header size on Netty when using HTTP/2"
  Set max request header size on Netty when using HTTP/2

Closes gh-36766

Author: mhalbritter

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/embedded/NettyWebServerFactoryCustomizer.java

@@ -66,6 +66,11 @@ public void customize(NettyReactiveWebServerFactory factory) {
 			.to((idleTimeout) -> customizeIdleTimeout(factory, idleTimeout));
 		propertyMapper.from(nettyProperties::getMaxKeepAliveRequests)
 			.to((maxKeepAliveRequests) -> customizeMaxKeepAliveRequests(factory, maxKeepAliveRequests));
+		if (this.serverProperties.getHttp2() != null && this.serverProperties.getHttp2().isEnabled()) {
+			propertyMapper.from(this.serverProperties.getMaxHttpHeaderSize())
+				.whenNonNull()
+				.to((size) -> customizeHttp2MaxHeaderSize(factory, size.toBytes()));
+		}
 		customizeRequestDecoder(factory, propertyMapper);
 	}
 
@@ -118,4 +123,9 @@ private void customizeMaxKeepAliveRequests(NettyReactiveWebServerFactory factory
 		factory.addServerCustomizers((httpServer) -> httpServer.maxKeepAliveRequests(maxKeepAliveRequests));
 	}
 
+	private void customizeHttp2MaxHeaderSize(NettyReactiveWebServerFactory factory, long size) {
+		factory.addServerCustomizers(
+				((httpServer) -> httpServer.http2Settings((settings) -> settings.maxHeaderListSize(size))));
+	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/embedded/NettyWebServerFactoryCustomizerTests.java

@@ -26,6 +26,7 @@
 import org.mockito.ArgumentCaptor;
 import org.mockito.Captor;
 import org.mockito.junit.jupiter.MockitoExtension;
+import reactor.netty.http.Http2SettingsSpec;
 import reactor.netty.http.server.HttpRequestDecoderSpec;
 import reactor.netty.http.server.HttpServer;
 
@@ -126,9 +127,20 @@ void setMaxKeepAliveRequests() {
 		verifyMaxKeepAliveRequests(factory, 100);
 	}
 
+	@Test
+	void setHttp2MaxRequestHeaderSize() {
+		DataSize headerSize = DataSize.ofKilobytes(24);
+		this.serverProperties.getHttp2().setEnabled(true);
+		this.serverProperties.setMaxHttpHeaderSize(headerSize);
+		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
+		this.customizer.customize(factory);
+		verifyHttp2MaxHeaderSize(factory, headerSize.toBytes());
+	}
+
 	@Test
 	void configureHttpRequestDecoder() {
 		ServerProperties.Netty nettyProperties = this.serverProperties.getNetty();
+		this.serverProperties.setMaxHttpHeaderSize(DataSize.ofKilobytes(24));
 		nettyProperties.setValidateHeaders(false);
 		nettyProperties.setInitialBufferSize(DataSize.ofBytes(512));
 		nettyProperties.setH2cMaxContentLength(DataSize.ofKilobytes(1));
@@ -137,10 +149,11 @@ void configureHttpRequestDecoder() {
 		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
 		this.customizer.customize(factory);
 		then(factory).should().addServerCustomizers(this.customizerCaptor.capture());
-		NettyServerCustomizer serverCustomizer = this.customizerCaptor.getValue();
+		NettyServerCustomizer serverCustomizer = this.customizerCaptor.getAllValues().get(0);
 		HttpServer httpServer = serverCustomizer.apply(HttpServer.create());
 		HttpRequestDecoderSpec decoder = httpServer.configuration().decoder();
 		assertThat(decoder.validateHeaders()).isFalse();
+		assertThat(decoder.maxHeaderSize()).isEqualTo(this.serverProperties.getMaxHttpHeaderSize().toBytes());
 		assertThat(decoder.initialBufferSize()).isEqualTo(nettyProperties.getInitialBufferSize().toBytes());
 		assertThat(decoder.h2cMaxContentLength()).isEqualTo(nettyProperties.getH2cMaxContentLength().toBytes());
 		assertThat(decoder.maxChunkSize()).isEqualTo(nettyProperties.getMaxChunkSize().toBytes());
@@ -179,4 +192,12 @@ private void verifyMaxKeepAliveRequests(NettyReactiveWebServerFactory factory, i
 		assertThat(maxKeepAliveRequests).isEqualTo(expected);
 	}
 
+	private void verifyHttp2MaxHeaderSize(NettyReactiveWebServerFactory factory, long expected) {
+		then(factory).should(times(2)).addServerCustomizers(this.customizerCaptor.capture());
+		NettyServerCustomizer serverCustomizer = this.customizerCaptor.getAllValues().get(0);
+		HttpServer httpServer = serverCustomizer.apply(HttpServer.create());
+		Http2SettingsSpec decoder = httpServer.configuration().http2SettingsSpec();
+		assertThat(decoder.maxHeaderListSize()).isEqualTo(expected);
+	}
+
 }