Disable Save-to-server when storage off, fix QR port 0 (#6473)

app/core/src/main/java/stirling/software/SPDF/controller/api/misc/ConfigController.java

@@ -119,11 +119,30 @@ public class ConfigController {
         String localIp = GeneralUtils.getLocalNetworkIp();
         if (localIp != null) {
             String scheme = appConfig.getBackendUrl().startsWith("https") ? "https" : "http";
-            return scheme + "://" + localIp + ":" + appConfig.getServerPort();
+            return scheme + "://" + localIp + ":" + resolveEffectiveServerPort(appConfig);
         }
         return "";
     }
 
+    /**
+     * The port the embedded server is actually listening on. With {@code server.port=0} (an
+     * ephemeral port, which the desktop bundle uses to dodge port clashes) the configured value
+     * stays {@code "0"} while Spring publishes the real bound port as {@code local.server.port}
+     * once the server is up. Advertised URLs (the mobile-scanner QR, share links) must carry the
+     * real port - a literal {@code :0} is unreachable and browsers reject it as ERR_UNSAFE_PORT.
+     */
+    // visible for testing
+    String resolveEffectiveServerPort(AppConfig appConfig) {
+        String configured = appConfig.getServerPort();
+        if (configured == null || "0".equals(configured.trim())) {
+            String actual = applicationContext.getEnvironment().getProperty("local.server.port");
+            if (actual != null && !actual.isBlank()) {
+                return actual;
+            }
+        }
+        return configured;
+    }
+
     private static boolean isLoopbackHost(String host) {
         return "localhost".equalsIgnoreCase(host)
                 || "127.0.0.1".equals(host)
@@ -161,7 +180,7 @@ public class ConfigController {
             // Note: Frontend expects "baseUrl" field name for compatibility
             configData.put("baseUrl", appConfig.getBackendUrl());
             configData.put("contextPath", appConfig.getContextPath());
-            configData.put("serverPort", appConfig.getServerPort());
+            configData.put("serverPort", resolveEffectiveServerPort(appConfig));
 
             String frontendUrl = applicationProperties.getSystem().getFrontendUrl();
             configData.put("frontendUrl", resolveFrontendUrl(request, appConfig));

app/core/src/test/java/stirling/software/SPDF/controller/api/misc/ConfigControllerTest.java

@@ -244,4 +244,52 @@ class ConfigControllerTest {
         assertNotNull(result);
         assertFalse(result.contains("localhost"));
     }
+
+    @Test
+    void resolveFrontendUrl_usesActualPortWhenServerPortIsEphemeral() {
+        System sys = mock(System.class);
+        when(applicationProperties.getSystem()).thenReturn(sys);
+        when(sys.getFrontendUrl()).thenReturn(null);
+
+        // Loopback host forces the detected-LAN-IP branch, which is where an
+        // ephemeral server.port=0 would otherwise leak through as ":0".
+        HttpServletRequest req = mock(HttpServletRequest.class);
+        when(req.getServerName()).thenReturn("localhost");
+
+        AppConfig appConfig = mock(AppConfig.class);
+        when(appConfig.getBackendUrl()).thenReturn("http://localhost");
+        when(appConfig.getServerPort()).thenReturn("0");
+
+        org.springframework.core.env.Environment environment =
+                mock(org.springframework.core.env.Environment.class);
+        when(applicationContext.getEnvironment()).thenReturn(environment);
+        when(environment.getProperty("local.server.port")).thenReturn("54321");
+
+        String result = configController.resolveFrontendUrl(req, appConfig);
+        assertNotNull(result);
+        assertTrue(result.endsWith(":54321"));
+        assertFalse(result.contains(":0"));
+    }
+
+    @Test
+    void resolveEffectiveServerPort_prefersActualBoundPortWhenConfiguredZero() {
+        AppConfig appConfig = mock(AppConfig.class);
+        when(appConfig.getServerPort()).thenReturn("0");
+
+        org.springframework.core.env.Environment environment =
+                mock(org.springframework.core.env.Environment.class);
+        when(applicationContext.getEnvironment()).thenReturn(environment);
+        when(environment.getProperty("local.server.port")).thenReturn("54321");
+
+        assertEquals("54321", configController.resolveEffectiveServerPort(appConfig));
+    }
+
+    @Test
+    void resolveEffectiveServerPort_keepsConfiguredNonZeroPort() {
+        AppConfig appConfig = mock(AppConfig.class);
+        when(appConfig.getServerPort()).thenReturn("8080");
+
+        // Non-zero configured port is authoritative; the runtime env is never consulted.
+        assertEquals("8080", configController.resolveEffectiveServerPort(appConfig));
+    }
 }