add documentation

Author: jdeniau

Diff for: Controller/IntrospectionController.php

@@ -70,21 +70,7 @@ public function __construct(
 
     public function introspectAction(Request $request): JsonResponse
     {
-        $clientToken = $this->tokenStorage->getToken(); // → use in security
-
-        if (!$clientToken instanceof OAuthToken) {
-            throw new AccessDeniedException('The introspect endpoint must be behind a secure firewall.');
-        }
-
-        $callerToken = $this->accessTokenManager->findTokenByToken($clientToken->getToken());
-
-        if (!$callerToken) {
-            throw new AccessDeniedException('The access token must have a valid token.');
-        }
-
-        if (!in_array($callerToken->getClientId(), $this->allowedIntrospectionClients)) {
-            throw new AccessDeniedException('This access token is not autorised to do introspection.');
-        }
+        $this->denyAccessIfNotAuthorizedClient();
 
         $token = $this->getToken($request);
 
@@ -106,6 +92,28 @@ public function introspectAction(Request $request): JsonResponse
         ]);
     }
 
+    /**
+     * Check that the caller has a token generated by an allowed client
+     */
+    private function denyAccessIfNotAuthorizedClient(): void
+    {
+        $clientToken = $this->tokenStorage->getToken();
+
+        if (!$clientToken instanceof OAuthToken) {
+            throw new AccessDeniedException('The introspect endpoint must be behind a secure firewall.');
+        }
+
+        $callerToken = $this->accessTokenManager->findTokenByToken($clientToken->getToken());
+
+        if (!$callerToken) {
+            throw new AccessDeniedException('The access token must have a valid token.');
+        }
+
+        if (!in_array($callerToken->getClientId(), $this->allowedIntrospectionClients)) {
+            throw new AccessDeniedException('This access token is not autorised to do introspection.');
+        }
+    }
+
     /**
      * @return TokenInterface|null
      */

Diff for: Resources/doc/index.md

@@ -624,3 +624,5 @@ The `authorize` endpoint is at `/oauth/v2/auth` by default (see `Resources/confi
 [Adding Grant Extensions](adding_grant_extensions.md)
 
 [Custom DB Driver](custom_db_driver.md)
+
+[Introspection endpoint](introspection_endpoint.md)

Diff for: Resources/doc/introspection_endpoint.md

@@ -0,0 +1,76 @@
+Introspection endpoint
+=========================================
+
+The OAuth 2.0 Token Introspection extension defines a protocol that returns information about an access token, intended to be used by resource servers or other internal servers.
+
+For more information, see [this explaination](https://www.oauth.com/oauth2-servers/token-introspection-endpoint/) or [the RFC 7662](https://tools.ietf.org/html/rfc7662).
+
+## Configuration
+
+Import the routing.yml configuration file in `app/config/routing.yml`:
+
+```yaml
+# app/config/routing.yml
+
+fos_oauth_server_introspection:
+    resource: "@FOSOAuthServerBundle/Resources/config/routing/introspection.xml"
+```
+
+Add FOSOAuthServerBundle settings in `app/config/config.yml`:
+
+```yaml
+fos_oauth_server:
+      introspection:
+          allowed_clients:
+              - 1_wUS0gjHdHyC2qeBL3u7RuIrIXClt6irL # an oauth client used only for token introspection. 
+```
+
+The allowed clients MUST be clients as defined [here](index.md#creating-a-client) and SHOULD be used only for token introspection (otherwise a endpoint client might call the introspection endpoint with its valid token).
+
+
+The introspection endpoint must be behind a firewall defined like this:
+
+```yaml
+# app/config/security.yml
+security:
+    firewalls:
+         oauth_introspect:
+              host: "%domain.oauth2%"
+              pattern: ^/oauth/v2/introspect
+              fos_oauth: true
+              stateless: true
+              anonymous: false
+```
+
+### Usage
+
+Then you can call the introspection endpoint like this:
+
+```
+POST /token_info
+Host: authorization-server.com
+Authorization: Bearer KvIu5v90GqgDctofFXP8npjC5DzMUkci
+ 
+token=SON4N82oVuRFykExk0iGTghihgOcI6bm
+```
+
+The JSON response will look like this if the token is inactive:
+
+```json
+{
+  "active": false
+}
+```
+
+If the token is active, the response will look like this:
+
+```json
+{
+  "active": true,
+  "scope": "scope1 scope2",
+  "client_id": "2_HC1KF0UrawHx05AxgNEeKJF10giBUOHZ",
+  "username": "foobar",
+  "token_type": "access_token",
+  "exp": 1534921182
+}
+```