/*
 * Copyright 2012-2021 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
 *
 *      https://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.boot.web.servlet.filter;

import java.io.IOException;

import javax.servlet.DispatcherType;
import javax.servlet.FilterChain;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContext;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.access.WebInvocationPrivilegeEvaluator;

/**
 * {@link HttpFilter} that intercepts error dispatches to ensure authorized access to the
 * error page.
 *
 * @author Madhura Bhave
 * @author Andy Wilkinson
 * @since 2.6.0
 */
public class ErrorPageSecurityFilter extends HttpFilter {

	private static final WebInvocationPrivilegeEvaluator ALWAYS = new AlwaysAllowWebInvocationPrivilegeEvaluator();

	private final ApplicationContext context;

	private volatile WebInvocationPrivilegeEvaluator privilegeEvaluator;

	public ErrorPageSecurityFilter(ApplicationContext context) {
		this.context = context;
	}

	@Override
	public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		if (DispatcherType.ERROR.equals(request.getDispatcherType())) {
			Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
			if (!getPrivilegeEvaluator().isAllowed(request.getRequestURI(), authentication)) {
				sendError(request, response);
				return;
			}
		}
		chain.doFilter(request, response);
	}

	private WebInvocationPrivilegeEvaluator getPrivilegeEvaluator() {
		WebInvocationPrivilegeEvaluator privilegeEvaluator = this.privilegeEvaluator;
		if (privilegeEvaluator == null) {
			privilegeEvaluator = getPrivilegeEvaluatorBean();
			this.privilegeEvaluator = privilegeEvaluator;
		}
		return privilegeEvaluator;
	}

	private WebInvocationPrivilegeEvaluator getPrivilegeEvaluatorBean() {
		try {
			return this.context.getBean(WebInvocationPrivilegeEvaluator.class);
		}
		catch (NoSuchBeanDefinitionException ex) {
			return ALWAYS;
		}
	}

	private void sendError(HttpServletRequest request, HttpServletResponse response) throws IOException {
		Integer errorCode = (Integer) request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE);
		response.sendError((errorCode != null) ? errorCode : 401);
	}

	/**
	 * {@link WebInvocationPrivilegeEvaluator} that always allows access.
	 */
	private static class AlwaysAllowWebInvocationPrivilegeEvaluator implements WebInvocationPrivilegeEvaluator {

		@Override
		public boolean isAllowed(String uri, Authentication authentication) {
			return true;
		}

		@Override
		public boolean isAllowed(String contextPath, String uri, String method, Authentication authentication) {
			return true;
		}

	}

}

@@ -736,16 +736,45 @@
 erType;%0A
+import javax.servlet.Filter;%0A
 import j
@@ -903,23 +903,60 @@
 let.
-http.HttpFilter
+ServletRequest;%0Aimport javax.servlet.ServletResponse
 ;%0Aim
@@ -1398,20 +1398,16 @@
  %7B@link 
-Http
 Filter%7D 
@@ -1604,20 +1604,19 @@
 ter 
-extend
+implement
 s 
-Http
 Filt
@@ -1979,194 +1979,621 @@
 ter(
-HttpServletRequest request, HttpServletResponse response, FilterChain chain)%0A%09%09%09throws IOException, ServletException %7B%0A%09%09if (DispatcherType.ERROR.equals(request.getDispatcherType())) %7B%0A%09
+ServletRequest request, ServletResponse response, FilterChain chain)%0A%09%09%09throws IOException, ServletException %7B%0A%09%09doFilter((HttpServletRequest) request, (HttpServletResponse) response, chain);%0A%09%7D%0A%0A%09private void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)%0A%09%09%09throws IOException, ServletException %7B%0A%09%09if (DispatcherType.ERROR.equals(request.getDispatcherType()) && !isAllowed(request)) %7B%0A%09%09%09sendError(request, response);%0A%09%09%09return;%0A%09%09%7D%0A%09%09chain.doFilter(request, response);%0A%09%7D%0A%0A%09private boolean isAllowed(HttpServletRequest request) %7B%0A%09%09String uri = request.getRequestURI();%0A
 %09%09Au
@@ -2684,14 +2684,15 @@
 ;%0A%09%09
-%09if (!
+return 
 getP
@@ -2725,141 +2725,27 @@
 wed(
-request.getRequestURI(), authentication)) %7B%0A%09%09%09%09sendError(request, response);%0A%09%09%09%09return;%0A%09%09%09%7D%0A%09%09%7D%0A%09%09chain.doFilter(request, response
+uri, authentication
 );%0A%09

Make ErrorPageSecurityFilter Servlet 3.1 compatible