Add support for configuring remaining Undertow server options

This commit adds support for configuring Undertow's server options that were previously
not configurable via application properties. The additions are the following:

- allow-encoded-slash
- always-set-keep-alive
- decode-url
- max-cookies
- max-headers
- max-parameters,
- url-charset

See gh-16278

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

@@ -58,6 +58,8 @@ import org.springframework.util.unit.DataSize;
  * @author Chentao Qu
  * @author Artsiom Yudovin
  * @author Andrew McGhie
+ * @author Rafiullah Hamedy
+ *
  */
 @ConfigurationProperties(prefix = "server", ignoreUnknownFields = true)
 public class ServerProperties {
@@ -1114,6 +1116,49 @@ public class ServerProperties {
 		 */
 		private boolean eagerFilterInit = true;
 
+		/**
+		 * The maximum number of query or path parameters that are allowed. This limit
+		 * exists to prevent hash collision based DOS attacks.
+		 */
+		private Integer maxParameters;
+
+		/**
+		 * The maximum number of headers that are allowed. This limit exists to prevent
+		 * hash collision based DOS attacks.
+		 */
+		private Integer maxHeaders;
+
+		/**
+		 * The maximum number of cookies that are allowed. This limit exists to prevent
+		 * hash collision based DOS attacks.
+		 */
+		private Integer maxCookies;
+
+		/**
+		 * Set this to true if you want the server to decode percent encoded slash
+		 * characters. This is probably a bad idea, as it can have security implications,
+		 * due to different servers interpreting the slash differently. Only enable this
+		 * if you have a legacy application that requires it.
+		 */
+		private Boolean allowEncodedSlash;
+
+		/**
+		 * If the URL should be decoded. If this is not set to true then percent encoded
+		 * characters in the URL will be left as is.
+		 */
+		private Boolean decodeUrl;
+
+		/**
+		 * The charset to decode the URL to.
+		 */
+		private String urlCharset;
+
+		/**
+		 * If the 'Connection: keep-alive' header should be added to all responses, even
+		 * if not required by spec.
+		 */
+		private Boolean alwaysSetKeepAlive;
+
 		private final Accesslog accesslog = new Accesslog();
 
 		public DataSize getMaxHttpPostSize() {
@@ -1164,6 +1209,62 @@ public class ServerProperties {
 			this.eagerFilterInit = eagerFilterInit;
 		}
 
+		public Integer getMaxParameters() {
+			return this.maxParameters;
+		}
+
+		public void setMaxParameters(Integer maxParameters) {
+			this.maxParameters = maxParameters;
+		}
+
+		public Integer getMaxHeaders() {
+			return this.maxHeaders;
+		}
+
+		public void setMaxHeaders(Integer maxHeaders) {
+			this.maxHeaders = maxHeaders;
+		}
+
+		public Integer getMaxCookies() {
+			return this.maxCookies;
+		}
+
+		public void setMaxCookies(Integer maxCookies) {
+			this.maxCookies = maxCookies;
+		}
+
+		public Boolean isAllowEncodedSlash() {
+			return this.allowEncodedSlash;
+		}
+
+		public void setAllowEncodedSlash(Boolean allowEncodedSlash) {
+			this.allowEncodedSlash = allowEncodedSlash;
+		}
+
+		public Boolean isDecodeUrl() {
+			return this.decodeUrl;
+		}
+
+		public void setDecodeUrl(Boolean decodeUrl) {
+			this.decodeUrl = decodeUrl;
+		}
+
+		public String getUrlCharset() {
+			return this.urlCharset;
+		}
+
+		public void setUrlCharset(String urlCharset) {
+			this.urlCharset = urlCharset;
+		}
+
+		public Boolean isAlwaysSetKeepAlive() {
+			return this.alwaysSetKeepAlive;
+		}
+
+		public void setAlwaysSetKeepAlive(Boolean alwaysSetKeepAlive) {
+			this.alwaysSetKeepAlive = alwaysSetKeepAlive;
+		}
+
 		public Accesslog getAccesslog() {
 			return this.accesslog;
 		}

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

@@ -16,9 +16,8 @@
 
 package org.springframework.boot.autoconfigure.web.embedded;
 
-import java.time.Duration;
-
 import io.undertow.UndertowOptions;
+import org.xnio.Option;
 
 import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.cloud.CloudPlatform;
@@ -38,6 +37,7 @@ import org.springframework.util.unit.DataSize;
  * @author Stephane Nicoll
  * @author Phillip Webb
  * @author Arstiom Yudovin
+ * @author Rafiullah Hamedy
  * @since 2.0.0
  */
 public class UndertowWebServerFactoryCustomizer implements
@@ -86,17 +86,50 @@ public class UndertowWebServerFactoryCustomizer implements
 				.to(factory::setAccessLogRotate);
 		propertyMapper.from(this::getOrDeduceUseForwardHeaders)
 				.to(factory::setUseForwardHeaders);
+
 		propertyMapper.from(properties::getMaxHttpHeaderSize).whenNonNull()
 				.asInt(DataSize::toBytes).when(this::isPositive)
-				.to((maxHttpHeaderSize) -> customizeMaxHttpHeaderSize(factory,
-						maxHttpHeaderSize));
+				.to((maxHttpHeaderSize) -> customizeProperties(factory,
+						UndertowOptions.MAX_HEADER_SIZE, maxHttpHeaderSize));
+
 		propertyMapper.from(undertowProperties::getMaxHttpPostSize)
 				.asInt(DataSize::toBytes).when(this::isPositive)
-				.to((maxHttpPostSize) -> customizeMaxHttpPostSize(factory,
-						maxHttpPostSize));
+				.to((maxHttpPostSize) -> customizeProperties(factory,
+						UndertowOptions.MAX_HEADER_SIZE, maxHttpPostSize));
+
 		propertyMapper.from(properties::getConnectionTimeout)
-				.to((connectionTimeout) -> customizeConnectionTimeout(factory,
-						connectionTimeout));
+				.to((connectionTimeout) -> customizeProperties(factory,
+						UndertowOptions.NO_REQUEST_TIMEOUT,
+						(int) connectionTimeout.toMillis()));
+
+		propertyMapper.from(undertowProperties::getMaxParameters)
+				.to((maxParameters) -> customizeProperties(factory,
+						UndertowOptions.MAX_PARAMETERS, maxParameters));
+
+		propertyMapper.from(undertowProperties::getMaxHeaders)
+				.to((maxHeaders) -> customizeProperties(factory,
+						UndertowOptions.MAX_HEADERS, maxHeaders));
+
+		propertyMapper.from(undertowProperties::getMaxCookies)
+				.to((maxCookies) -> customizeProperties(factory,
+						UndertowOptions.MAX_COOKIES, maxCookies));
+
+		propertyMapper.from(undertowProperties::isAllowEncodedSlash)
+				.to((allowEncodedSlash) -> customizeProperties(factory,
+						UndertowOptions.ALLOW_ENCODED_SLASH, allowEncodedSlash));
+
+		propertyMapper.from(undertowProperties::isDecodeUrl)
+				.to((isDecodeUrl) -> customizeProperties(factory,
+						UndertowOptions.DECODE_URL, isDecodeUrl));
+
+		propertyMapper.from(undertowProperties::getUrlCharset)
+				.to((urlCharset) -> customizeProperties(factory,
+						UndertowOptions.URL_CHARSET, urlCharset));
+
+		propertyMapper.from(undertowProperties::isAlwaysSetKeepAlive)
+				.to((alwaysSetKeepAlive) -> customizeProperties(factory,
+						UndertowOptions.ALWAYS_SET_KEEP_ALIVE, alwaysSetKeepAlive));
+
 		factory.addDeploymentInfoCustomizers((deploymentInfo) -> deploymentInfo
 				.setEagerFilterInit(undertowProperties.isEagerFilterInit()));
 	}
@@ -105,22 +138,10 @@ public class UndertowWebServerFactoryCustomizer implements
 		return value.longValue() > 0;
 	}
 
-	private void customizeConnectionTimeout(ConfigurableUndertowWebServerFactory factory,
-			Duration connectionTimeout) {
-		factory.addBuilderCustomizers((builder) -> builder.setServerOption(
-				UndertowOptions.NO_REQUEST_TIMEOUT, (int) connectionTimeout.toMillis()));
-	}
-
-	private void customizeMaxHttpHeaderSize(ConfigurableUndertowWebServerFactory factory,
-			int maxHttpHeaderSize) {
-		factory.addBuilderCustomizers((builder) -> builder
-				.setServerOption(UndertowOptions.MAX_HEADER_SIZE, maxHttpHeaderSize));
-	}
-
-	private void customizeMaxHttpPostSize(ConfigurableUndertowWebServerFactory factory,
-			long maxHttpPostSize) {
-		factory.addBuilderCustomizers((builder) -> builder
-				.setServerOption(UndertowOptions.MAX_ENTITY_SIZE, maxHttpPostSize));
+	private <T> void customizeProperties(ConfigurableUndertowWebServerFactory factory,
+			Option<T> propType, T prop) {
+		factory.addBuilderCustomizers(
+				(builder) -> builder.setServerOption(propType, prop));
 	}
 
 	private boolean getOrDeduceUseForwardHeaders() {

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

@@ -48,6 +48,8 @@ import static org.mockito.Mockito.verify;
  * @author Brian Clozel
  * @author Phillip Webb
  * @author Artsiom Yudovin
+ * @author Rafiullah Hamedy
+ *
  */
 public class UndertowWebServerFactoryCustomizerTests {
 
@@ -85,6 +87,40 @@ public class UndertowWebServerFactoryCustomizerTests {
 		verify(factory).setAccessLogRotate(false);
 	}
 
+	@Test
+	public void customizeUndertowConnectionCommonSettings() {
+		bind("server.undertow.maxParameters=50", "server.undertow.maxHeaders=60",
+				"server.undertow.maxCookies=70", "server.undertow.allowEncodedSlash=true",
+				"server.undertow.decodeUrl=true", "server.undertow.urlCharset=UTF-8",
+				"server.undertow.alwaysSetKeepAlive=true");
+		Builder builder = Undertow.builder();
+		ConfigurableUndertowWebServerFactory factory = mockFactory(builder);
+		this.customizer.customize(factory);
+		OptionMap map = ((OptionMap.Builder) ReflectionTestUtils.getField(builder,
+				"serverOptions")).getMap();
+		assertThat(map.get(UndertowOptions.MAX_PARAMETERS)).isEqualTo(50);
+		assertThat(map.get(UndertowOptions.MAX_HEADERS)).isEqualTo(60);
+		assertThat(map.get(UndertowOptions.MAX_COOKIES)).isEqualTo(70);
+		assertThat(map.get(UndertowOptions.ALLOW_ENCODED_SLASH)).isTrue();
+		assertThat(map.get(UndertowOptions.DECODE_URL)).isTrue();
+		assertThat(map.get(UndertowOptions.URL_CHARSET)).isEqualTo("UTF-8");
+		assertThat(map.get(UndertowOptions.ALWAYS_SET_KEEP_ALIVE)).isTrue();
+	}
+
+	@Test
+	public void customizeUndertowCommonConnectionCommonBoolSettings() {
+		bind("server.undertow.allowEncodedSlash=false", "server.undertow.decodeUrl=false",
+				"server.undertow.alwaysSetKeepAlive=false");
+		Builder builder = Undertow.builder();
+		ConfigurableUndertowWebServerFactory factory = mockFactory(builder);
+		this.customizer.customize(factory);
+		OptionMap map = ((OptionMap.Builder) ReflectionTestUtils.getField(builder,
+				"serverOptions")).getMap();
+		assertThat(map.get(UndertowOptions.ALLOW_ENCODED_SLASH)).isFalse();
+		assertThat(map.get(UndertowOptions.DECODE_URL)).isFalse();
+		assertThat(map.get(UndertowOptions.ALWAYS_SET_KEEP_ALIVE)).isFalse();
+	}
+
 	@Test
 	public void deduceUseForwardHeaders() {
 		this.environment.setProperty("DYNO", "-");