Fix subdomain middleware

src/Middleware/InitializeTenancyBySubdomain.php

@@ -5,15 +5,13 @@ declare(strict_types=1);
 namespace Stancl\Tenancy\Middleware;
 
 use Closure;
+use Exception;
 use Illuminate\Http\Response;
 use Illuminate\Support\Str;
 use Stancl\Tenancy\Exceptions\NotASubdomainException;
 
 class InitializeTenancyBySubdomain extends InitializeTenancyByDomain
 {
-    /** @var callable|null */
-    public static $onInvalidSubdomain;
-
     /**
      * The index of the subdomain fragment in the hostname
      * split by `.`. 0 for first fragment, 1 if you prefix
@@ -37,19 +35,27 @@ class InitializeTenancyBySubdomain extends InitializeTenancyByDomain
     {
         $subdomain = $this->makeSubdomain($request->getHost());
 
-        // If a non-string, like a Response instance was returned
-        // from makeSubdomain() - due to NotASubDomainException
-        // being thrown, we abort by returning the value now.
-        if (! is_string($subdomain)) {
+        if (is_object($subdomain) && $subdomain instanceof Exception) {
+            $onFail = static::$onFail ?? function ($e) {
+                throw $e;
+            };
+
+            return $onFail($subdomain, $request, $next);
+        }
+
+        // If a Response instance was returned, we return it immediately.
+        if (is_object($subdomain) && $subdomain instanceof Response) {
             return $subdomain;
         }
 
         return $this->initializeTenancy(
-            $request, $next, $subdomain
+            $request,
+            $next,
+            $subdomain
         );
     }
 
-    /** @return string|Response|mixed */
+    /** @return string|Response|Exception|mixed */
     protected function makeSubdomain(string $hostname)
     {
         $parts = explode('.', $hostname);
@@ -58,15 +64,12 @@ class InitializeTenancyBySubdomain extends InitializeTenancyByDomain
         $isIpAddress = count(array_filter($parts, 'is_numeric')) === count($parts);
 
         // If we're on localhost or an IP address, then we're not visiting a subdomain.
+        $isACentralDomain = in_array($hostname, config('tenancy.central_domains'), true);
         $notADomain = $isLocalhost || $isIpAddress;
-        $thirdPartyDomain = ! Str::endsWith($hostname, config('tenancy.central_domains'));
+        $thirdPartyDomain = !Str::endsWith($hostname, config('tenancy.central_domains'));
 
-        if ($notADomain || $thirdPartyDomain) {
-            $handle = static::$onInvalidSubdomain ?? function ($e) {
-                throw $e;
-            };
-
-            return $handle(new NotASubdomainException($hostname));
+        if ($isACentralDomain || $notADomain || $thirdPartyDomain) {
+            return new NotASubdomainException($hostname);
         }
 
         return $parts[static::$subdomainIndex];

tests/SubdomainTest.php

@@ -17,7 +17,7 @@ class SubdomainTest extends TestCase
         parent::setUp();
 
         // Global state cleanup after some tests
-        InitializeTenancyBySubdomain::$onInvalidSubdomain = null;
+        InitializeTenancyBySubdomain::$onFail = null;
 
         Route::group([
             'middleware' => InitializeTenancyBySubdomain::class,
@@ -88,8 +88,12 @@ class SubdomainTest extends TestCase
     {
         // in this case, we need to return a response instance
         // since a string would be treated as the subdomain
-        InitializeTenancyBySubdomain::$onInvalidSubdomain = function () {
+        InitializeTenancyBySubdomain::$onFail = function ($e) {
+            if ($e instanceof NotASubdomainException) {
                 return response('foo custom invalid subdomain handler');
+            }
+
+            throw $e;
         };
 
         $this
@@ -120,6 +124,28 @@ class SubdomainTest extends TestCase
             ->withoutExceptionHandling()
             ->get('http://foo.localhost/foo/abc/xyz');
     }
+
+    /** @test */
+    public function central_domain_is_not_a_subdomain()
+    {
+        config(['tenancy.central_domains' => [
+            'localhost',
+        ]]);
+
+        $tenant = SubdomainTenant::create([
+            'id' => 'acme',
+        ]);
+
+        $tenant->domains()->create([
+            'domain' => 'acme',
+        ]);
+
+        $this->expectException(NotASubdomainException::class);
+
+        $this
+            ->withoutExceptionHandling()
+            ->get('http://localhost/foo/abc/xyz');
+    }
 }
 
 class SubdomainTenant extends Models\Tenant