Merge pull request #18 from metosin/EatYourOwn

Match is injected into request

README.md

@@ -179,7 +179,7 @@ Path-based routing:
 
 On match, route meta-data is returned and can interpreted by the  application.
 
-Routers also support meta-data compilation enabling things like fast [Ring](https://github.com/ring-clojure/ring) or [Pedestal](http://pedestal.io/) -style handlers. Compilation results are found under `:handler` in the match. See [configuring routers](configuring-routers) for details.
+Routers also support meta-data compilation enabling things like fast [Ring](https://github.com/ring-clojure/ring) or [Pedestal](http://pedestal.io/) -style handlers. Compilation results are found under `:handler` in the match. See [configuring routers](#configuring-routers) for details.
 
 ## Ring
 
@@ -281,6 +281,59 @@ Nested middleware works too:
 
 Ring-router supports also 3-arity [Async Ring](https://www.booleanknot.com/blog/2016/07/15/asynchronous-ring.html), so it can be used on [Node.js](https://nodejs.org/en/) too.
 
+### Meta-data based extensions
+
+The routing `Match` is injected into a request and can be extracted with `reitit.ring/get-match` helper. It can be used to build dynamic extensions to the system.
+
+A middleware to guard routes:
+
+```clj
+(require '[clojure.set :as set])
+
+(defn wrap-enforce-roles [handler]
+  (fn [{:keys [::roles] :as request}]
+    (let [required (some-> request (ring/get-match) :meta ::roles)]
+      (if (and (seq required) (not (set/intersection required roles)))
+        {:status 403, :body "forbidden"}
+        (handler request)))))
+```
+
+Mounted to an app via router meta-data (effecting all routes):
+
+```clj
+(def handler (constantly {:status 200, :body "ok"}))
+
+(def app
+  (ring/ring-handler
+    (ring/router
+      [["/api"
+        ["/ping" handler]
+        ["/admin" {::roles #{:admin}}
+         ["/ping" handler]]]]
+      {:meta {:middleware [wrap-enforce-roles]}})))
+```
+
+Anonymous access to public route:
+
+```clj
+(app {:request-method :get, :uri "/api/ping"})
+; {:status 200, :body "ok"}
+```
+
+Anonymous access to guarded route:
+
+```clj
+(app {:request-method :get, :uri "/api/admin/ping"})
+; {:status 403, :body "forbidden"}
+```
+
+Authorized access to guarded route:
+
+```clj
+(app {:request-method :get, :uri "/api/admin/ping", ::roles #{:admin}})
+; {:status 200, :body "ok"}
+```
+
 ## Validating route-tree
 
 **TODO**
@@ -297,10 +350,6 @@ Ring-router supports also 3-arity [Async Ring](https://www.booleanknot.com/blog/
 
 **TODO**
 
-## Custom extensions
-
-**TODO**
-
 ## Configuring Routers
 
 Routers can be configured via options to do things like custom coercion and compilatin of meta-data. These can be used to do things like [`clojure.spec`](https://clojure.org/about/spec) validation of meta-data and fast, compiled [Ring](https://github.com/ring-clojure/ring/wiki/Concepts) or [Pedestal](http://pedestal.io/) -style handlers.

src/reitit/middleware.cljc

@@ -1,5 +1,6 @@
 (ns reitit.middleware
-  (:require [reitit.core :as reitit]))
+  (:require [meta-merge.core :refer [meta-merge]]
+            [reitit.core :as reitit]))
 
 (defprotocol ExpandMiddleware
   (expand-middleware [this]))
@@ -40,5 +41,9 @@
    (ensure-handler! path meta scope)
    ((compose-middleware middleware) handler)))
 
-(defn router [data]
-  (reitit/router data {:compile compile-handler}))
+(defn router
+  ([data]
+   (router data nil))
+  ([data opts]
+   (let [opts (meta-merge {:compile compile-handler} opts)]
+     (reitit/router data opts))))

src/reitit/ring.cljc

@@ -18,15 +18,18 @@
     (fn
       ([request]
        (if-let [match (reitit/match-by-path router (:uri request))]
-         ((:handler match) request)))
+         ((:handler match) (assoc request ::match match))))
       ([request respond raise]
        (if-let [match (reitit/match-by-path router (:uri request))]
-         ((:handler match) request respond raise))))
+         ((:handler match) (assoc request ::match match) respond raise))))
     {::router router}))
 
 (defn get-router [handler]
   (some-> handler meta ::router))
 
+(defn get-match [request]
+  (::match request))
+
 (defn coerce-handler [[path meta] {:keys [expand]}]
   [path (reduce
           (fn [acc method]
@@ -53,6 +56,10 @@
            (if-let [handler (resolved-handler (:request-method request))]
              (handler request respond raise))))))))
 
-(defn router [data]
-  (reitit/router data {:coerce coerce-handler
-                       :compile compile-handler}))
+(defn router
+  ([data]
+   (router data nil))
+  ([data opts]
+   (let [opts (meta-merge {:coerce coerce-handler
+                           :compile compile-handler} opts)]
+     (reitit/router data opts))))

test/cljc/reitit/ring_test.cljc

@@ -1,7 +1,8 @@
 (ns reitit.ring-test
   (:require [clojure.test :refer [deftest testing is]]
             [reitit.middleware :as middleware]
-            [reitit.ring :as ring])
+            [reitit.ring :as ring]
+            [clojure.set :as set])
   #?(:clj
      (:import (clojure.lang ExceptionInfo))))
 
@@ -122,3 +123,35 @@
           (app {:uri "/api/users" :request-method :post} respond raise)
           (is (= {:status 200, :body [:api :users :post :ok :post :users :api]}
                  @result)))))))
+
+(defn wrap-enforce-roles [handler]
+  (fn [{:keys [::roles] :as request}]
+    (let [required (some-> request (ring/get-match) :meta ::roles)]
+      (if (and (seq required) (not (set/intersection required roles)))
+        {:status 403, :body "forbidden"}
+        (handler request)))))
+
+(deftest enforcing-meta-data-rules-at-runtime-test
+  (let [handler (constantly {:status 200, :body "ok"})
+        app (ring/ring-handler
+              (ring/router
+                [["/api"
+                  ["/ping" handler]
+                  ["/admin" {::roles #{:admin}}
+                   ["/ping" handler]]]]
+                {:meta {:middleware [wrap-enforce-roles]}}))]
+
+    (testing "public handler"
+      (is (= {:status 200, :body "ok"}
+             (app {:uri "/api/ping" :request-method :get}))))
+
+    (testing "runtime-enforced handler"
+      (testing "without needed roles"
+        (is (= {:status 403 :body "forbidden"}
+               (app {:uri "/api/admin/ping"
+                     :request-method :get}))))
+      (testing "with needed roles"
+        (is (= {:status 200, :body "ok"}
+               (app {:uri "/api/admin/ping"
+                     :request-method :get
+                     ::roles #{:admin}})))))))