feat: generate a nonce to validate the OAuth callback

3 files changed, 31 insertions, 7 deletions

diff --git a/app/controllers/sessions/controller.go b/app/controllers/sessions/controller.go
index 7e706e7..7549dc7 100644
--- a/app/controllers/sessions/controller.go
+++ b/app/controllers/sessions/controller.go
@@ -3,9 +3,11 @@ package sessions
 import (
 	"context"
 	"net/http"
+	"time"
 
 	"github.com/xlgmokha/x/pkg/log"
 	"gitlab.com/gitlab-org/software-supply-chain-security/authorization/sparkled/pkg/oidc"
+	"gitlab.com/gitlab-org/software-supply-chain-security/authorization/sparkled/pkg/pls"
 	"gitlab.com/gitlab-org/software-supply-chain-security/authorization/sparkled/pkg/web/cookie"
 	"golang.org/x/oauth2"
 )
@@ -29,8 +31,9 @@ func (c *Controller) MountTo(mux *http.ServeMux) {
 }
 
 func (c *Controller) New(w http.ResponseWriter, r *http.Request) {
-	// TODO:: Generate and store nonce and use as state param to compare as a CSRF token
-	url := c.cfg.Config.AuthCodeURL("todo-csrf-token", oauth2.SetAuthURLParam("audience", "todo"))
+	nonce := pls.GenerateNonce(32)
+	url := c.cfg.Config.AuthCodeURL(nonce, oauth2.SetAuthURLParam("audience", c.cfg.Config.ClientID))
+	http.SetCookie(w, cookie.New("oauth_state", nonce, time.Now().Add(10*time.Minute)))
 	http.Redirect(w, r, url, http.StatusFound)
 }
 
diff --git a/app/controllers/sessions/controller_test.go b/app/controllers/sessions/controller_test.go
index e325afc..64c9fc1 100644
--- a/app/controllers/sessions/controller_test.go
+++ b/app/controllers/sessions/controller_test.go
@@ -37,11 +37,11 @@ func TestSessions(t *testing.T) {
 
 	t.Run("GET /session/new", func(t *testing.T) {
 		t.Run("without an authenticated session", func(t *testing.T) {
-			t.Run("redirect to the OIDC Provider", func(t *testing.T) {
-				r, w := test.RequestResponse("GET", "/session/new")
+			r, w := test.RequestResponse("GET", "/session/new")
 
-				mux.ServeHTTP(w, r)
+			mux.ServeHTTP(w, r)
 
+			t.Run("redirect to the OIDC Provider", func(t *testing.T) {
 				require.Equal(t, http.StatusFound, w.Code)
 				require.NotEmpty(t, w.Header().Get("Location"))
 				redirectURL, err := url.Parse(w.Header().Get("Location"))
@@ -50,12 +50,22 @@ func TestSessions(t *testing.T) {
 				assert.NotEmpty(t, redirectURL.Query().Get("state"))
 				assert.Equal(t, srv.MockOIDC.Config().ClientID, redirectURL.Query().Get("client_id"))
 				assert.Equal(t, "openid profile email", redirectURL.Query().Get("scope"))
-				assert.Equal(t, "todo", redirectURL.Query().Get("audience"))
+				assert.Equal(t, cfg.Config.ClientID, redirectURL.Query().Get("audience"))
 				assert.Equal(t, cfg.Config.RedirectURL, redirectURL.Query().Get("redirect_uri"))
 				assert.Equal(t, "code", redirectURL.Query().Get("response_type"))
 			})
 
-			t.Run("generates a CSRF token", func(t *testing.T) {})
+			t.Run("generates a CSRF token", func(t *testing.T) {
+				cookieHeader := w.Header().Get("Set-Cookie")
+				require.NotEmpty(t, cookieHeader)
+
+				cookies, err := http.ParseCookie(cookieHeader)
+				require.NoError(t, err)
+				cookie := x.Find(cookies, func(item *http.Cookie) bool {
+					return item.Name == "oauth_state"
+				})
+				require.NotZero(t, cookie)
+			})
 		})
 
 		t.Run("with an active authenicated session", func(t *testing.T) {})
diff --git a/pkg/pls/nonce.go b/pkg/pls/nonce.go
new file mode 100644
index 0000000..aeab640
--- /dev/null
+++ b/pkg/pls/nonce.go
@@ -0,0 +1,11 @@
+package pls
+
+import (
+	"crypto/rand"
+)
+
+func GenerateNonce(size int) string {
+	nonceBytes := make([]byte, size)
+	rand.Read(nonceBytes)
+	return string(nonceBytes)
+}