Added support for Tomcat Remote IP Filter

CHANGELOG.md

@@ -10,6 +10,7 @@
 * [HELM] Improved method for setting extra env variables on HTTP and MQTT pods.
 * [HELM] Add database connection to Keycloak provider.
 * Added setting for sessionCookiePath.
+* Added support for [Tomcat Remote IP Filter](https://tomcat.apache.org/tomcat-9.0-doc/config/filter.html#Remote_IP_Filter).
 
 **Internal changes & Bugfixes**
 * Improved generated queries when fetching entities over a one-to-many relation.

FROST-Server.HTTP.Common/src/main/java/de/fraunhofer/iosb/ilt/frostserver/http/common/AbstractContextListener.java

@@ -93,6 +93,8 @@ public void contextInitialized(ServletContextEvent sce) {
                 initCoreSettings(context);
                 context.setAttribute(TAG_CORE_SETTINGS, coreSettings);
 
+                IpFilterHelper.setupRemoteIpFilter(context, coreSettings);
+
                 setUpCorsFilter(context, coreSettings);
 
                 PersistenceManagerFactory.init(coreSettings);

FROST-Server.HTTP.Common/src/main/java/de/fraunhofer/iosb/ilt/frostserver/http/common/IpFilterHelper.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2024 Fraunhofer Institut IOSB, Fraunhoferstr. 1, D 76131
+ * Karlsruhe, Germany.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package de.fraunhofer.iosb.ilt.frostserver.http.common;
+
+import de.fraunhofer.iosb.ilt.frostserver.settings.ConfigProvider;
+import de.fraunhofer.iosb.ilt.frostserver.settings.CoreSettings;
+import de.fraunhofer.iosb.ilt.frostserver.settings.Settings;
+import de.fraunhofer.iosb.ilt.frostserver.settings.annotation.DefaultValueBoolean;
+import de.fraunhofer.iosb.ilt.frostserver.util.StringHelper;
+import java.util.EnumSet;
+import javax.servlet.DispatcherType;
+import javax.servlet.FilterRegistration;
+import javax.servlet.ServletContext;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Helper class for setting up the tomcat Remote-IP-Filter.
+ *
+ * @see
+ * https://tomcat.apache.org/tomcat-9.0-doc/config/filter.html#Remote_IP_Filter
+ */
+public class IpFilterHelper extends ConfigProvider<IpFilterHelper> {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(IpFilterHelper.class.getName());
+
+    public static final String PREFIX_REMOTE_IP_FILTER = "remoteIpFilter.";
+    public static final String NAME_REMOTE_IP_FILTER = "RemoteIpFilter";
+    public static final String NAME_CLASS_REMOTE_IP_FILTER = "org.apache.catalina.filters.RemoteIpFilter";
+
+    @DefaultValueBoolean(false)
+    public static final String TAG_ENABLE = "enable";
+
+    public IpFilterHelper(Settings settings) {
+        super(settings);
+    }
+
+    public static void setupRemoteIpFilter(ServletContext servletContext, CoreSettings coreSettings) {
+        Settings httpSettings = coreSettings.getHttpSettings();
+        new IpFilterHelper(httpSettings.getSubSettings(PREFIX_REMOTE_IP_FILTER))
+                .setupFilter(servletContext);
+
+    }
+
+    private void setupFilter(ServletContext servletContext) {
+        if (!getBoolean(TAG_ENABLE)) {
+            return;
+        }
+        try {
+            FilterRegistration.Dynamic ripFilter = servletContext.addFilter(NAME_REMOTE_IP_FILTER, NAME_CLASS_REMOTE_IP_FILTER);
+            ripFilter.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD), true, "/*");
+            setInitParameter(ripFilter, "enableLookups");
+            setInitParameter(ripFilter, "remoteIpHeader");
+            setInitParameter(ripFilter, "internalProxies");
+            setInitParameter(ripFilter, "proxiesHeader");
+            setInitParameter(ripFilter, "requestAttributesEnabled");
+            setInitParameter(ripFilter, "trustedProxies");
+            setInitParameter(ripFilter, "protocolHeader");
+            setInitParameter(ripFilter, "hostHeader");
+            setInitParameter(ripFilter, "hostHeader");
+            setInitParameter(ripFilter, "protocolHeaderHttpsValue");
+            setInitParameter(ripFilter, "httpServerPort");
+            setInitParameter(ripFilter, "httpsServerPort");
+            setInitParameter(ripFilter, "changeLocalName");
+            setInitParameter(ripFilter, "changeLocalPort");
+        } catch (Exception exc) {
+            LOGGER.error("Failed to initialise RemoteIpFilter.", exc);
+        }
+    }
+
+    private void setInitParameter(FilterRegistration.Dynamic filter, String pramName) {
+        String value = getSettings().get(pramName, "");
+        if (!StringHelper.isNullOrEmpty(value)) {
+            filter.setInitParameter(pramName, value);
+        }
+    }
+
+    @Override
+    public IpFilterHelper getThis() {
+        return this;
+    }
+
+}