Implement both synchronous (1-arity) and async (3-arity) Ring handler fns #54

README.md

@@ -132,6 +132,28 @@ and complete authentication of the user.
 
 [the specification]: https://tools.ietf.org/html/rfc6749#section-2.3.1
 
+### Custom error handlers
+
+You can override the default error handlers by providing the appropriate
+keys in a profile:
+```clojure
+  (wrap-oauth2
+   routes
+   {:github
+     {...
+      :no-auth-code-handler   my-no-auth-code-handler
+      :state-mismatch-handler my-state-mistmatch-handler}})
+```
+Note that your handlers must offer the correct function arity
+whether Ring and your HTTP server are being run in synchronous (1-arity)
+or asynchronous (3-arity) mode.
+
+### Synchronous and async Ring
+
+This middleware supports both synchronous mode (1-arity Ring handler
+functions) and asynchronous mode (3-arity).
+However, the implementation is currently synchronous by nature.
+
 ### PKCE
 
 Some OAuth providers require an additional step called *Proof Key for

src/ring/middleware/oauth2.clj

@@ -117,17 +117,25 @@
        basic-auth? (add-header-credentials client-id client-secret)
        (not basic-auth?) (add-form-credentials client-id client-secret)))))
 
-(defn state-mismatch-handler [_]
-  {:status 400, :headers {}, :body "State mismatch"})
+(defn- make-error-response-handler-fn [message]
+  (let [response {:status  400
+                  :headers {}
+                  :body    message}]
+    (fn
+      ([_request]                response)
+      ([_request respond _raise] (respond response)))))
 
-(defn no-auth-code-handler [_]
-  {:status 400, :headers {}, :body "No authorization code"})
+(def default-state-mismatch-handler
+  (make-error-response-handler-fn "State mismatch"))
+
+(def default-no-auth-code-handler
+  (make-error-response-handler-fn "No authorization code"))
 
 (defn- make-redirect-handler [{:keys [id landing-uri] :as profile}]
-  (let [state-mismatch-handler (:state-mismatch-handler
-                                 profile state-mismatch-handler)
-        no-auth-code-handler   (:no-auth-code-handler
-                                 profile no-auth-code-handler)]
+  (let [state-mismatch-handler (get profile :state-mismatch-handler
+                                            default-state-mismatch-handler)
+        no-auth-code-handler   (get profile :no-auth-code-handler
+                                            default-no-auth-code-handler)]
     (fn [{:keys [session] :or {session {}} :as request}]
       (cond
         (not (state-matches? request))
@@ -158,10 +166,15 @@
   {:pre [(every? valid-profile? (vals profiles))]}
   (let [profiles  (for [[k v] profiles] (assoc v :id k))
         launches  (into {} (map (juxt :launch-uri identity)) profiles)
-        redirects (into {} (map (juxt parse-redirect-url identity)) profiles)]
-    (fn [{:keys [uri] :as request}]
-      (if-let [profile (launches uri)]
-        ((make-launch-handler profile) request)
-        (if-let [profile (redirects uri)]
-          ((:redirect-handler profile (make-redirect-handler profile)) request)
-          (handler (assoc-access-tokens request)))))))
+        redirects (into {} (map (juxt parse-redirect-url identity)) profiles)
+        f         (fn [{:keys [uri] :as request}]
+                     (if-let [profile (launches uri)]
+                       ((make-launch-handler profile) request)
+                       (if-let [profile (redirects uri)]
+                         ((:redirect-handler profile 
+                                             (make-redirect-handler profile)) 
+                          request)
+                         (handler (assoc-access-tokens request)))))]
+    (fn
+      ([request]           (f request))
+      ([request respond _] (respond (f request))))))