Avoid rejecting same-origin requests detected as CORS requests

Browsers like Chrome or Safari include an Origin header for same-origin
POST/PUT/DELETE requests, not only for cross-origin requests.

Before this commit, these same-origin requests would have been detected
as potential cross-origin requests, and rejected if the same-origin domain
is not part of the configured allowedOrigins.

This commit avoid to reject same-origin requests by reusing the logic
introduced in Spring 4.1 for detecting reliably Websocket/SockJS
same-origin requests with the WebUtils.isValidOrigin() method. This
logic has been extracted in a new WebUtils.isSameOrigin() method.

Issue: SPR-13206

spring-web/src/main/java/org/springframework/web/cors/DefaultCorsProcessor.java

@@ -35,6 +35,7 @@ import org.springframework.http.server.ServerHttpResponse;
 import org.springframework.http.server.ServletServerHttpRequest;
 import org.springframework.http.server.ServletServerHttpResponse;
 import org.springframework.util.CollectionUtils;
+import org.springframework.web.util.WebUtils;
 
 /**
  * Default implementation of {@link CorsProcessor}, as defined by the
@@ -42,7 +43,9 @@ import org.springframework.util.CollectionUtils;
  *
  * <p>Note that when input {@link CorsConfiguration} is {@code null}, this
  * implementation does not reject simple or actual requests outright but simply
- * avoid adding CORS headers to the response.
+ * avoid adding CORS headers to the response. CORS processing is also skipped
+ * if the response already contains CORS headers, or if the request is detected
+ * as a same-origin one.
  *
  * @author Sebastien Deleuze
  * @author Rossen Stoyanhcev
@@ -66,12 +69,16 @@ public class DefaultCorsProcessor implements CorsProcessor {
 		ServletServerHttpResponse serverResponse = new ServletServerHttpResponse(response);
 		ServletServerHttpRequest serverRequest = new ServletServerHttpRequest(request);
 
+		if (WebUtils.isSameOrigin(serverRequest)) {
+			logger.debug("Skip CORS processing, request is a same-origin one");
+			return true;
+		}
 		if (responseHasCors(serverResponse)) {
+			logger.debug("Skip CORS processing, response already contains \"Access-Control-Allow-Origin\" header");
 			return true;
 		}
 
 		boolean preFlightRequest = CorsUtils.isPreFlightRequest(request);
-
 		if (config == null) {
 			if (preFlightRequest) {
 				rejectRequest(serverResponse);
@@ -93,9 +100,6 @@ public class DefaultCorsProcessor implements CorsProcessor {
 		catch (NullPointerException npe) {
 			// SPR-11919 and https://issues.jboss.org/browse/WFLY-3474
 		}
-		if (hasAllowOrigin) {
-			logger.debug("Skip adding CORS headers, response already contains \"Access-Control-Allow-Origin\"");
-		}
 		return hasAllowOrigin;
 	}
 

spring-web/src/main/java/org/springframework/web/util/WebUtils.java

@@ -789,15 +789,30 @@ public abstract class WebUtils {
 			return true;
 		}
 		else if (CollectionUtils.isEmpty(allowedOrigins)) {
-			UriComponents actualUrl = UriComponentsBuilder.fromHttpRequest(request).build();
-			UriComponents originUrl = UriComponentsBuilder.fromOriginHeader(origin).build();
-			return (actualUrl.getHost().equals(originUrl.getHost()) && getPort(actualUrl) == getPort(originUrl));
+			return isSameOrigin(request);
 		}
 		else {
 			return allowedOrigins.contains(origin);
 		}
 	}
 
+	/**
+	 * Check if the request is a same-origin one, based on {@code Origin}, {@code Host},
+	 * {@code Forwarded} and {@code X-Forwarded-Host} headers.
+	 * @return {@code true} if the request is a same-origin one, {@code false} in case
+	 * of cross-origin request.
+	 * @since 4.2
+	 */
+	public static boolean isSameOrigin(HttpRequest request) {
+		String origin = request.getHeaders().getOrigin();
+		if (origin == null) {
+			return true;
+		}
+		UriComponents actualUrl = UriComponentsBuilder.fromHttpRequest(request).build();
+		UriComponents originUrl = UriComponentsBuilder.fromOriginHeader(origin).build();
+		return (actualUrl.getHost().equals(originUrl.getHost()) && getPort(actualUrl) == getPort(originUrl));
+	}
+
 	private static int getPort(UriComponents component) {
 		int port = component.getPort();
 		if (port == -1) {

spring-web/src/test/java/org/springframework/web/util/WebUtilsTests.java

@@ -106,37 +106,47 @@ public class WebUtilsTests {
 	}
 
 	@Test
-	public void isValidOriginSuccess() {
-
+	public void isValidOrigin() {
 		List<String> allowed = Collections.emptyList();
-		assertTrue(checkOrigin("mydomain1.com", -1, "http://mydomain1.com", allowed));
-		assertTrue(checkOrigin("mydomain1.com", -1, "http://mydomain1.com:80", allowed));
-		assertTrue(checkOrigin("mydomain1.com", 443, "https://mydomain1.com", allowed));
-		assertTrue(checkOrigin("mydomain1.com", 443, "https://mydomain1.com:443", allowed));
-		assertTrue(checkOrigin("mydomain1.com", 123, "http://mydomain1.com:123", allowed));
-		assertTrue(checkOrigin("mydomain1.com", -1, "ws://mydomain1.com", allowed));
-		assertTrue(checkOrigin("mydomain1.com", 443, "wss://mydomain1.com", allowed));
+		assertTrue(checkValidOrigin("mydomain1.com", -1, "http://mydomain1.com", allowed));
+		assertFalse(checkValidOrigin("mydomain1.com", -1, "http://mydomain2.com", allowed));
 
 		allowed = Collections.singletonList("*");
-		assertTrue(checkOrigin("mydomain1.com", -1, "http://mydomain2.com", allowed));
+		assertTrue(checkValidOrigin("mydomain1.com", -1, "http://mydomain2.com", allowed));
 
 		allowed = Collections.singletonList("http://mydomain1.com");
-		assertTrue(checkOrigin("mydomain2.com", -1, "http://mydomain1.com", allowed));
+		assertTrue(checkValidOrigin("mydomain2.com", -1, "http://mydomain1.com", allowed));
+		assertFalse(checkValidOrigin("mydomain2.com", -1, "http://mydomain3.com", allowed));
 	}
 
 	@Test
-	public void isValidOriginFailure() {
+	public void isSameOrigin() {
+		assertTrue(checkSameOrigin("mydomain1.com", -1, "http://mydomain1.com"));
+		assertTrue(checkSameOrigin("mydomain1.com", -1, "http://mydomain1.com:80"));
+		assertTrue(checkSameOrigin("mydomain1.com", 443, "https://mydomain1.com"));
+		assertTrue(checkSameOrigin("mydomain1.com", 443, "https://mydomain1.com:443"));
+		assertTrue(checkSameOrigin("mydomain1.com", 123, "http://mydomain1.com:123"));
+		assertTrue(checkSameOrigin("mydomain1.com", -1, "ws://mydomain1.com"));
+		assertTrue(checkSameOrigin("mydomain1.com", 443, "wss://mydomain1.com"));
+
+		assertFalse(checkSameOrigin("mydomain1.com", -1, "http://mydomain2.com"));
+		assertFalse(checkSameOrigin("mydomain1.com", -1, "https://mydomain1.com"));
+		assertFalse(checkSameOrigin("mydomain1.com", -1, "invalid-origin"));
+	}
 
-		List<String> allowed = Collections.emptyList();
-		assertFalse(checkOrigin("mydomain1.com", -1, "http://mydomain2.com", allowed));
-		assertFalse(checkOrigin("mydomain1.com", -1, "https://mydomain1.com", allowed));
-		assertFalse(checkOrigin("mydomain1.com", -1, "invalid-origin", allowed));
 
-		allowed = Collections.singletonList("http://mydomain1.com");
-		assertFalse(checkOrigin("mydomain2.com", -1, "http://mydomain3.com", allowed));
+	private boolean checkValidOrigin(String serverName, int port, String originHeader, List<String> allowed) {
+		MockHttpServletRequest servletRequest = new MockHttpServletRequest();
+		ServerHttpRequest request = new ServletServerHttpRequest(servletRequest);
+		servletRequest.setServerName(serverName);
+		if (port != -1) {
+			servletRequest.setServerPort(port);
+		}
+		request.getHeaders().set(HttpHeaders.ORIGIN, originHeader);
+		return WebUtils.isValidOrigin(request, allowed);
 	}
 
-	private boolean checkOrigin(String serverName, int port, String originHeader, List<String> allowed) {
+	private boolean checkSameOrigin(String serverName, int port, String originHeader) {
 		MockHttpServletRequest servletRequest = new MockHttpServletRequest();
 		ServerHttpRequest request = new ServletServerHttpRequest(servletRequest);
 		servletRequest.setServerName(serverName);
@@ -144,7 +154,7 @@ public class WebUtilsTests {
 			servletRequest.setServerPort(port);
 		}
 		request.getHeaders().set(HttpHeaders.ORIGIN, originHeader);
-		return WebUtils.isValidOrigin(request, allowed);
+		return WebUtils.isSameOrigin(request);
 	}
 
 }