001/* 002 * Copyright 2002-2019 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.web.cors.reactive; 018 019import reactor.core.publisher.Mono; 020 021import org.springframework.http.server.reactive.ServerHttpRequest; 022import org.springframework.util.Assert; 023import org.springframework.web.cors.CorsConfiguration; 024import org.springframework.web.server.ServerWebExchange; 025import org.springframework.web.server.WebFilter; 026import org.springframework.web.server.WebFilterChain; 027 028 029/** 030 * {@link WebFilter} that handles CORS preflight requests and intercepts 031 * CORS simple and actual requests thanks to a {@link CorsProcessor} implementation 032 * ({@link DefaultCorsProcessor} by default) in order to add the relevant CORS 033 * response headers (like {@code Access-Control-Allow-Origin}) using the provided 034 * {@link CorsConfigurationSource} (for example an {@link UrlBasedCorsConfigurationSource} 035 * instance. 036 * 037 * <p>This is an alternative to Spring WebFlux Java config CORS configuration, 038 * mostly useful for applications using the functional API. 039 * 040 * @author Sebastien Deleuze 041 * @since 5.0 042 * @see <a href="https://www.w3.org/TR/cors/">CORS W3C recommendation</a> 043 */ 044public class CorsWebFilter implements WebFilter { 045 046 private final CorsConfigurationSource configSource; 047 048 private final CorsProcessor processor; 049 050 051 /** 052 * Constructor accepting a {@link CorsConfigurationSource} used by the filter 053 * to find the {@link CorsConfiguration} to use for each incoming request. 054 * @see UrlBasedCorsConfigurationSource 055 */ 056 public CorsWebFilter(CorsConfigurationSource configSource) { 057 this(configSource, new DefaultCorsProcessor()); 058 } 059 060 /** 061 * Constructor accepting a {@link CorsConfigurationSource} used by the filter 062 * to find the {@link CorsConfiguration} to use for each incoming request and a 063 * custom {@link CorsProcessor} to use to apply the matched 064 * {@link CorsConfiguration} for a request. 065 * @see UrlBasedCorsConfigurationSource 066 */ 067 public CorsWebFilter(CorsConfigurationSource configSource, CorsProcessor processor) { 068 Assert.notNull(configSource, "CorsConfigurationSource must not be null"); 069 Assert.notNull(processor, "CorsProcessor must not be null"); 070 this.configSource = configSource; 071 this.processor = processor; 072 } 073 074 075 @Override 076 public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) { 077 ServerHttpRequest request = exchange.getRequest(); 078 CorsConfiguration corsConfiguration = this.configSource.getCorsConfiguration(exchange); 079 boolean isValid = this.processor.process(corsConfiguration, exchange); 080 if (!isValid || CorsUtils.isPreFlightRequest(request)) { 081 return Mono.empty(); 082 } 083 return chain.filter(exchange); 084 } 085 086}