From f0e31227928566a27c8a0a14d27f1c411c7dfce2 Mon Sep 17 00:00:00 2001
From: stianst <stianst@gmail.com>
Date: Fri, 14 Feb 2020 10:52:36 +0100
Subject: [PATCH] KEYCLOAK-12953 Ignore empty realm frontendUrl

---
 .../keycloak/url/DefaultHostnameProvider.java |  2 +-
 .../testsuite/url/DefaultHostnameTest.java    | 21 +++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/services/src/main/java/org/keycloak/url/DefaultHostnameProvider.java b/services/src/main/java/org/keycloak/url/DefaultHostnameProvider.java
index 1472a10dd9..9f01d84957 100644
--- a/services/src/main/java/org/keycloak/url/DefaultHostnameProvider.java
+++ b/services/src/main/java/org/keycloak/url/DefaultHostnameProvider.java
@@ -97,7 +97,7 @@ public class DefaultHostnameProvider implements HostnameProvider {
             realmUri = null;
 
             String realmFrontendUrl = session.getContext().getRealm().getAttribute("frontendUrl");
-            if (realmFrontendUrl != null) {
+            if (realmFrontendUrl != null && !realmFrontendUrl.isEmpty()) {
                 try {
                     realmUri = new URI(realmFrontendUrl);
                 } catch (URISyntaxException e) {
diff --git a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/url/DefaultHostnameTest.java b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/url/DefaultHostnameTest.java
index 2114ff21b1..2398e1cc77 100644
--- a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/url/DefaultHostnameTest.java
+++ b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/url/DefaultHostnameTest.java
@@ -9,6 +9,7 @@ import org.jboss.arquillian.test.api.ArquillianResource;
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.keycloak.admin.client.Keycloak;
+import org.keycloak.admin.client.resource.RealmResource;
 import org.keycloak.broker.provider.util.SimpleHttp;
 import org.keycloak.client.registration.Auth;
 import org.keycloak.client.registration.ClientRegistration;
@@ -99,6 +100,26 @@ public class DefaultHostnameTest extends AbstractHostnameTest {
         }
     }
 
+    // KEYCLOAK-12953
+    @Test
+    public void emptyRealmFrontendUrl() throws URISyntaxException {
+        expectedBackendUrl = AUTH_SERVER_ROOT;
+        oauth.clientId("direct-grant");
+
+        RealmResource realmResource = realmsResouce().realm("frontendUrl");
+        RealmRepresentation rep = realmResource.toRepresentation();
+
+        try {
+            rep.getAttributes().put("frontendUrl", "");
+            realmResource.update(rep);
+
+            assertWellKnown("frontendUrl", AUTH_SERVER_ROOT);
+        } finally {
+            rep.getAttributes().put("frontendUrl", realmFrontEndUrl);
+            realmResource.update(rep);
+        }
+    }
+
     @Test
     public void fixedAdminUrl() throws Exception {
         expectedBackendUrl = AUTH_SERVER_ROOT;