Make ForwardedHeadersFilter.serverPort nullable

See gh-2658

Author: spencergibb

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@@ -317,10 +317,11 @@ public SecureHeadersProperties secureHeadersProperties() {
 
 	@Bean
 	@ConditionalOnProperty(name = "spring.cloud.gateway.forwarded.enabled", matchIfMissing = true)
-	public ForwardedHeadersFilter forwardedHeadersFilter(Environment env) {
+	public ForwardedHeadersFilter forwardedHeadersFilter(Environment env, ServerProperties serverProperties) {
 		boolean forwardedByEnabled = env.getProperty("spring.cloud.gateway.forwarded.by.enabled", Boolean.class, false);
 		ForwardedHeadersFilter forwardedHeadersFilter = new ForwardedHeadersFilter();
 		forwardedHeadersFilter.setForwardedByEnabled(forwardedByEnabled);
+		forwardedHeadersFilter.setServerPort(serverProperties.getPort());
 		return forwardedHeadersFilter;
 	}
 

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/headers/ForwardedHeadersFilter.java

@@ -29,7 +29,6 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
-import org.springframework.beans.factory.annotation.Value;
 import org.springframework.core.Ordered;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.server.reactive.ServerHttpRequest;
@@ -45,8 +44,7 @@
  */
 public class ForwardedHeadersFilter implements HttpHeadersFilter, Ordered {
 
-	@Value("${server.port}")
-	private int serverPort;
+	private Integer serverPort;
 
 	private final Log logger = LogFactory.getLog(getClass());
 
@@ -104,6 +102,10 @@ public void setForwardedByEnabled(boolean forwardedByEnabled) {
 		this.forwardedByEnabled = forwardedByEnabled;
 	}
 
+	public void setServerPort(Integer serverPort) {
+		this.serverPort = serverPort;
+	}
+
 	@Override
 	public int getOrder() {
 		return 0;
@@ -179,7 +181,7 @@ private void addForwardedByHeader(Forwarded forwarded) {
 			if (localAddress instanceof Inet6Address) {
 				byValue = "[" + byValue + "]";
 			}
-			if (serverPort > 0) {
+			if (serverPort != null && serverPort > 0) {
 				byValue = byValue + ":" + serverPort;
 			}
 			forwarded.put("by", byValue);