CFM-527_API_v2_JSON_endpoints_return_incorrect_Content-Type_text/html_instead_of_application_json

app/config/routes.php

@@ -22,6 +22,7 @@
  */
 
 use Cake\Http\Middleware\BodyParserMiddleware;
+use App\Middleware\ForceJsonIfAcceptedMiddleware;
 use Cake\Http\Middleware\CsrfProtectionMiddleware;
 use Cake\Routing\Route\DashedRoute;
 use Cake\Routing\RouteBuilder;
@@ -54,12 +55,16 @@
   // BodyParserMiddleware will automatically parse JSON bodies, but we only
   // want that for API transactions, so we only apply it to the /api scope.
   $builder->registerMiddleware('bodyparser', new BodyParserMiddleware());
+  $builder->registerMiddleware('forceJsonIfAccepted', new ForceJsonIfAcceptedMiddleware());
+
   /*
    * Apply a middleware to the current route scope.
    * Requires middleware to be registered through `Application::routes()` with `registerMiddleware()`
    */
   $builder->setExtensions(['json']);
   $builder->applyMiddleware('bodyparser');
+  $builder->applyMiddleware('forceJsonIfAccepted');
+
   // Use setPass to make parameter show up as function parameter
   // Model specific actions, which will usually have more specific URLs:
   // Note that while the UI uses dashes in URL paths, because we use {model} for the generic

app/src/Middleware/ForceJsonIfAcceptedMiddleware.php

@@ -0,0 +1,91 @@
+<?php
+/**
+ * COmanage Registry Force Json If Accepted Middleware
+ *
+ * Portions licensed to the University Corporation for Advanced Internet
+ * Development, Inc. ("UCAID") under one or more contributor license agreements.
+ * See the NOTICE file distributed with this work for additional information
+ * regarding copyright ownership.
+ *
+ * UCAID licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with the
+ * License. You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @link          https://www.internet2.edu/comanage COmanage Project
+ * @package       registry
+ * @since         COmanage Registry v5.3.0
+ * @license       Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
+ */
+
+declare(strict_types=1);
+
+namespace App\Middleware;
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+
+final class ForceJsonIfAcceptedMiddleware implements MiddlewareInterface
+{
+  /**
+   * If the client indicates it accepts JSON (via route extension or Accept header),
+   * ensure the response advertises JSON unless it is already JSON.
+   *
+   * @since  COmanage Registry v5.3.0
+   * @param  \Psr\Http\Message\ServerRequestInterface $request Request
+   * @param  \Psr\Http\Server\RequestHandlerInterface $handler Handler
+   * @return \Psr\Http\Message\ResponseInterface Response
+   */
+  public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+  {
+    $response = $handler->handle($request);
+
+    if (!$this->clientWantsJson($request)) {
+      return $response;
+    }
+
+    // If it's already JSON, leave it alone.
+    $contentType = strtolower($response->getHeaderLine('Content-Type'));
+    if ($contentType !== '' && str_contains($contentType, 'application/json')) {
+      return $response;
+    }
+
+    // Otherwise override to JSON.
+    return $response->withHeader('Content-Type', 'application/json; charset=UTF-8');
+  }
+
+  /**
+   * Determine whether the client indicates it wants JSON.
+   *
+   * Currently supports an explicit route extension of "json" and Accept headers
+   * including "application/json" and vendor-specific "+json" media types.
+   *
+   * @since  COmanage Registry v5.3.0
+   * @param  \Psr\Http\Message\ServerRequestInterface $request Request
+   * @return bool True if the client indicates JSON is acceptable/preferred
+   */
+  private function clientWantsJson(ServerRequestInterface $request): bool
+  {
+    $params = $request->getAttribute('params');
+    if (is_array($params) && (($params['_ext'] ?? null) === 'json')) {
+      return true;
+    }
+
+    $accept = strtolower($request->getHeaderLine('Accept'));
+
+    if (str_contains($accept, 'application/json')) {
+      return true;
+    }
+
+    return preg_match('/application\/[^;,+]+\+json\b/', $accept) === 1;
+  }
+}