Encapsulate CORS checking within CorsConfiguration

CorsConfiguration now provides methods to check and determine the
allowed origin, method, and headers according to its own configuration.

This simplifies significantly the work that needs to be done from
DefaultCorsProcessor. However an alternative CorsProcessor can still
access the raw CorsConfiguration and perform its own checks.

Issue: SPR-12885

spring-web/src/test/java/org/springframework/web/cors/CorsConfigurationTests.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2002-2015 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.web.cors;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.http.HttpMethod;
+
+/**
+ * Test case for {@link CorsConfiguration}.
+ *
+ * @author Sebastien Deleuze
+ */
+public class CorsConfigurationTests {
+
+	private CorsConfiguration config;
+
+	@Before
+	public void setup() {
+		config = new CorsConfiguration();
+	}
+
+	@Test
+	public void checkOriginAllowed() {
+		config.setAllowedOrigins(Arrays.asList("*"));
+		assertEquals("*", config.checkOrigin("http://domain.com"));
+		config.setAllowCredentials(true);
+		assertEquals("http://domain.com", config.checkOrigin("http://domain.com"));
+		config.setAllowedOrigins(Arrays.asList("http://domain.com"));
+		assertEquals("http://domain.com", config.checkOrigin("http://domain.com"));
+		config.setAllowCredentials(false);
+		assertEquals("http://domain.com", config.checkOrigin("http://domain.com"));
+	}
+
+	@Test
+	public void checkOriginNotAllowed() {
+		assertNull(config.checkOrigin(null));
+		assertNull(config.checkOrigin("http://domain.com"));
+		config.addAllowedOrigin("*");
+		assertNull(config.checkOrigin(null));
+		config.setAllowedOrigins(Arrays.asList("http://domain1.com"));
+		assertNull(config.checkOrigin("http://domain2.com"));
+		config.setAllowedOrigins(new ArrayList<>());
+		assertNull(config.checkOrigin("http://domain.com"));
+	}
+
+	@Test
+	public void checkMethodAllowed() {
+		assertEquals(Arrays.asList(HttpMethod.GET), config.checkHttpMethod(HttpMethod.GET));
+		config.addAllowedMethod("GET");
+		assertEquals(Arrays.asList(HttpMethod.GET), config.checkHttpMethod(HttpMethod.GET));
+		config.addAllowedMethod("POST");
+		assertEquals(Arrays.asList(HttpMethod.GET, HttpMethod.POST), config.checkHttpMethod(HttpMethod.GET));
+		assertEquals(Arrays.asList(HttpMethod.GET, HttpMethod.POST), config.checkHttpMethod(HttpMethod.POST));
+	}
+
+	@Test
+	public void checkMethodNotAllowed() {
+		assertNull(config.checkHttpMethod(null));
+		assertNull(config.checkHttpMethod(HttpMethod.DELETE));
+		config.setAllowedMethods(new ArrayList<>());
+		assertNull(config.checkHttpMethod(HttpMethod.HEAD));
+	}
+
+	@Test
+	public void checkHeadersAllowed() {
+		assertEquals(Collections.emptyList(), config.checkHeaders(Collections.emptyList()));
+		config.addAllowedHeader("header1");
+		config.addAllowedHeader("header2");
+		assertEquals(Arrays.asList("header1"), config.checkHeaders(Arrays.asList("header1")));
+		assertEquals(Arrays.asList("header1", "header2"), config.checkHeaders(Arrays.asList("header1", "header2")));
+		assertEquals(Arrays.asList("header1", "header2"), config.checkHeaders(Arrays.asList("header1", "header2", "header3")));
+	}
+
+	@Test
+	public void checkHeadersNotAllowed() {
+		assertNull(config.checkHeaders(null));
+		assertNull(config.checkHeaders(Arrays.asList("header1")));
+		config.addAllowedHeader("header2");
+		assertNull(config.checkHeaders(Arrays.asList("header1")));
+		config.setAllowedHeaders(new ArrayList<>());
+		assertNull(config.checkHeaders(Arrays.asList("header1")));
+	}
+
+}

spring-web/src/test/java/org/springframework/web/cors/DefaultCorsProcessorTests.java

@@ -243,7 +243,7 @@ public class DefaultCorsProcessorTests {
 	}
 
 	@Test
-	public void preflightRequestCrendentialsWithOriginWildcard() throws Exception {
+	public void preflightRequestCredentialsWithOriginWildcard() throws Exception {
 		this.request.setMethod(HttpMethod.OPTIONS.name());
 		this.request.addHeader(HttpHeaders.ORIGIN, "http://domain2.com/test.html");
 		this.request.addHeader(HttpHeaders.ACCESS_CONTROL_REQUEST_HEADERS, "Header1");