KEYCLOAK-1391: Return an HTTP 401 for API requests

Non browser HTTP requests shouldn't redirect to the Keycloak login
page. Instead, return an HTTP 401 with a proper WWW-Authenticate
header.

integration/spring-security/src/main/java/org/keycloak/adapters/springsecurity/authentication/HttpHeaderInspectingApiRequestMatcher.java

@@ -0,0 +1,38 @@
+package org.keycloak.adapters.springsecurity.authentication;
+
+import org.apache.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.security.web.util.matcher.RequestMatcher;
+
+import javax.servlet.http.HttpServletRequest;
+
+/**
+ * {@link RequestMatcher} that determines if a given request is an API request or an
+ * interactive login request.
+ *
+ * @author <a href="mailto:srossillo@smartling.com">Scott Rossillo</a>
+ * @see RequestMatcher
+ */
+public class HttpHeaderInspectingApiRequestMatcher implements RequestMatcher {
+
+    protected static final String X_REQUESTED_WITH_HEADER = "X-Requested-With";
+    protected static final String X_REQUESTED_WITH_HEADER_AJAX_VALUE = "XMLHttpRequest";
+
+    /**
+     * Returns true if the given request is an API request or false if it's an interactive
+     * login request.
+     *
+     * @param request the <code>HttpServletRequest</code>
+     * @return <code>true</code> if the given <code>request</code> is an API request;
+     * <code>false</code> otherwise
+     */
+    @Override
+    public boolean matches(HttpServletRequest request) {
+        boolean ajax = X_REQUESTED_WITH_HEADER_AJAX_VALUE.equals(request.getHeader(X_REQUESTED_WITH_HEADER));
+        boolean html = request.getHeader(HttpHeaders.ACCEPT) != null && request.getHeader(HttpHeaders.ACCEPT).contains(
+                MediaType.TEXT_HTML_VALUE);
+
+        return ajax || !html;
+    }
+
+}

integration/spring-security/src/main/java/org/keycloak/adapters/springsecurity/authentication/KeycloakAuthenticationEntryPoint.java

@@ -1,9 +1,12 @@
 package org.keycloak.adapters.springsecurity.authentication;
 
+import org.apache.http.HttpHeaders;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpStatus;
 import org.springframework.security.core.AuthenticationException;
 import org.springframework.security.web.AuthenticationEntryPoint;
+import org.springframework.security.web.util.matcher.RequestMatcher;
 import org.springframework.util.Assert;
 
 import javax.servlet.ServletException;
@@ -12,10 +15,15 @@ import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
 
 /**
- * Provides a Keycloak {@link AuthenticationEntryPoint authentication entry point}.
+ * Provides a Keycloak {@link AuthenticationEntryPoint authentication entry point}. Uses a
+ * {@link RequestMatcher} to determine if the request is an interactive login request or a
+ * API request, which should not be redirected to an interactive login page. By default,
+ * this entry point uses a {@link HttpHeaderInspectingApiRequestMatcher} but can be overridden using in the
+ * constructor.
  *
  * @author <a href="mailto:srossillo@smartling.com">Scott Rossillo</a>
- * @version $Revision: 1 $
+ *
+ * @see HttpHeaderInspectingApiRequestMatcher
  */
 public class KeycloakAuthenticationEntryPoint implements AuthenticationEntryPoint {
 
@@ -23,23 +31,62 @@ public class KeycloakAuthenticationEntryPoint implements AuthenticationEntryPoin
      * Default Keycloak authentication login URI
      */
     public static final String DEFAULT_LOGIN_URI = "/sso/login";
+    private static final String DEFAULT_REALM = "Unknown";
+    private static final RequestMatcher DEFAULT_API_REQUEST_MATCHER = new HttpHeaderInspectingApiRequestMatcher();
 
     private final static Logger log = LoggerFactory.getLogger(KeycloakAuthenticationEntryPoint.class);
 
+    private final RequestMatcher apiRequestMatcher;
     private String loginUri = DEFAULT_LOGIN_URI;
+    private String realm = DEFAULT_REALM;
+
+    /**
+     * Creates a new Keycloak authentication entry point.
+     */
+    public KeycloakAuthenticationEntryPoint() {
+        this(DEFAULT_API_REQUEST_MATCHER);
+    }
+
+    /**
+     * Creates a new Keycloak authentication entry point using the given request
+     * matcher to determine if the current request is an API request or a browser request.
+     *
+     * @param apiRequestMatcher the <code>RequestMatcher</code> to use to determine
+     * if the current request is an API request or a browser request (required)
+     */
+    public KeycloakAuthenticationEntryPoint(RequestMatcher apiRequestMatcher) {
+        Assert.notNull(apiRequestMatcher, "apiRequestMatcher required");
+        this.apiRequestMatcher = apiRequestMatcher;
+    }
 
     @Override
-    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException)
-            throws IOException, ServletException {
+    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException
+    {
+        if (apiRequestMatcher.matches(request)) {
+            commenceUnauthorizedResponse(request, response);
+        } else {
+            commenceLoginRedirect(request, response);
+        }
+    }
 
+    protected void commenceLoginRedirect(HttpServletRequest request, HttpServletResponse response) throws IOException {
         String contextAwareLoginUri = request.getContextPath() + loginUri;
-
         log.debug("Redirecting to login URI {}", contextAwareLoginUri);
         response.sendRedirect(contextAwareLoginUri);
     }
 
+    protected void commenceUnauthorizedResponse(HttpServletRequest request, HttpServletResponse response) throws IOException {
+        response.addHeader(HttpHeaders.WWW_AUTHENTICATE, String.format("Bearer realm=\"%s\"", realm));
+        response.sendError(HttpStatus.UNAUTHORIZED.value(), HttpStatus.UNAUTHORIZED.getReasonPhrase());
+    }
+
     public void setLoginUri(String loginUri) {
         Assert.notNull(loginUri, "loginUri cannot be null");
         this.loginUri = loginUri;
     }
+
+    public void setRealm(String realm) {
+        Assert.notNull(realm, "realm cannot be null");
+        this.realm = realm;
+    }
 }

integration/spring-security/src/test/java/org/keycloak/adapters/springsecurity/authentication/HttpHeaderInspectingApiRequestMatcherTest.java

@@ -0,0 +1,43 @@
+package org.keycloak.adapters.springsecurity.authentication;
+
+import org.apache.http.HttpHeaders;
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.security.web.util.matcher.RequestMatcher;
+
+import static org.junit.Assert.*;
+
+/**
+ * HTTP header inspecting API request matcher tests.
+ */
+public class HttpHeaderInspectingApiRequestMatcherTest {
+
+    private RequestMatcher apiRequestMatcher = new HttpHeaderInspectingApiRequestMatcher();
+    private MockHttpServletRequest request;
+
+    @Before
+    public void setUp() throws Exception {
+        request = new MockHttpServletRequest();
+    }
+
+    @Test
+    public void testMatches() throws Exception {
+        assertTrue(apiRequestMatcher.matches(request));
+    }
+
+    @Test
+    public void testMatchesBrowserRequest() throws Exception {
+        request.addHeader(HttpHeaders.ACCEPT, "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
+        assertFalse(apiRequestMatcher.matches(request));
+    }
+
+    @Test
+    public void testMatchesRequestedWith() throws Exception {
+        request.addHeader(
+                HttpHeaderInspectingApiRequestMatcher.X_REQUESTED_WITH_HEADER,
+                HttpHeaderInspectingApiRequestMatcher.X_REQUESTED_WITH_HEADER_AJAX_VALUE);
+        assertTrue(apiRequestMatcher.matches(request));
+    }
+
+}

integration/spring-security/src/test/java/org/keycloak/adapters/springsecurity/authentication/KeycloakAuthenticationEntryPointTest.java

@@ -1,5 +1,6 @@
 package org.keycloak.adapters.springsecurity.authentication;
 
+import org.apache.http.HttpHeaders;
 import org.junit.Before;
 import org.junit.Test;
 import org.springframework.http.HttpStatus;
@@ -25,14 +26,16 @@ public class KeycloakAuthenticationEntryPointTest {
     }
 
     @Test
-    public void testCommence() throws Exception {
+    public void testCommenceWithRedirect() throws Exception {
+        configureBrowserRequest();
         authenticationEntryPoint.commence(request, response, null);
         assertEquals(HttpStatus.FOUND.value(), response.getStatus());
         assertEquals(KeycloakAuthenticationEntryPoint.DEFAULT_LOGIN_URI, response.getHeader("Location"));
     }
 
     @Test
-    public void testCommenceNotRootContext() throws Exception {
+    public void testCommenceWithRedirectNotRootContext() throws Exception {
+        configureBrowserRequest();
         String contextPath = "/foo";
         request.setContextPath(contextPath);
         authenticationEntryPoint.commence(request, response, null);
@@ -40,12 +43,25 @@ public class KeycloakAuthenticationEntryPointTest {
         assertEquals(contextPath + KeycloakAuthenticationEntryPoint.DEFAULT_LOGIN_URI, response.getHeader("Location"));
     }
 
+    @Test
+    public void testCommenceWithUnauthorizedWithAccept() throws Exception {
+        request.addHeader(HttpHeaders.ACCEPT, "application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
+        authenticationEntryPoint.commence(request, response, null);
+        assertEquals(HttpStatus.UNAUTHORIZED.value(), response.getStatus());
+        assertNotNull(response.getHeader(HttpHeaders.WWW_AUTHENTICATE));
+    }
+
     @Test
     public void testSetLoginUri() throws Exception {
+        configureBrowserRequest();
         final String logoutUri = "/foo";
         authenticationEntryPoint.setLoginUri(logoutUri);
         authenticationEntryPoint.commence(request, response, null);
         assertEquals(HttpStatus.FOUND.value(), response.getStatus());
         assertEquals(logoutUri, response.getHeader("Location"));
     }
+
+    private void configureBrowserRequest() {
+        request.addHeader(HttpHeaders.ACCEPT, "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
+    }
 }