Add support for Feature-Policy security header

web/src/main/java/org/springframework/security/web/header/writers/FeaturePolicyHeaderWriter.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.web.header.writers;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.springframework.security.web.header.HeaderWriter;
+import org.springframework.util.Assert;
+
+/**
+ * Provides support for <a href="https://wicg.github.io/feature-policy/">Feature
+ * Policy</a>.
+ * <p>
+ * Feature Policy allows web developers to selectively enable, disable, and modify the
+ * behavior of certain APIs and web features in the browser.
+ * <p>
+ * A declaration of a feature policy contains a set of security policy directives, each
+ * responsible for declaring the restrictions for a particular feature type.
+ *
+ * @author Vedran Pavic
+ * @since 5.1
+ */
+public final class FeaturePolicyHeaderWriter implements HeaderWriter {
+
+	private static final String FEATURE_POLICY_HEADER = "Feature-Policy";
+
+	private String policyDirectives;
+
+	/**
+	 * Create a new instance of {@link FeaturePolicyHeaderWriter} with supplied security
+	 * policy directive(s).
+	 *
+	 * @param policyDirectives the security policy directive(s)
+	 * @throws IllegalArgumentException if policyDirectives is {@code null} or empty
+	 */
+	public FeaturePolicyHeaderWriter(String policyDirectives) {
+		setPolicyDirectives(policyDirectives);
+	}
+
+	@Override
+	public void writeHeaders(HttpServletRequest request, HttpServletResponse response) {
+		response.setHeader(FEATURE_POLICY_HEADER, this.policyDirectives);
+	}
+
+	/**
+	 * Set the security policy directive(s) to be used in the response header.
+	 *
+	 * @param policyDirectives the security policy directive(s)
+	 * @throws IllegalArgumentException if policyDirectives is {@code null} or empty
+	 */
+	public void setPolicyDirectives(String policyDirectives) {
+		Assert.hasLength(policyDirectives, "policyDirectives must not be null or empty");
+		this.policyDirectives = policyDirectives;
+	}
+
+	@Override
+	public String toString() {
+		return getClass().getName() + " [policyDirectives=" + this.policyDirectives + "]";
+	}
+
+}