[oidc] consider returnTo URL

Author: AlexTugarev

components/public-api-server/pkg/oidc/router.go

@@ -42,8 +42,13 @@ func (s *Service) getStartHandler() http.HandlerFunc {
 			return
 		}
 
+		returnToURL := r.URL.Query().Get("returnTo")
+		if returnToURL == "" {
+			returnToURL = "/"
+		}
+
 		redirectURL := getCallbackURL(r.Host)
-		startParams, err := s.GetStartParams(config, redirectURL)
+		startParams, err := s.GetStartParams(config, redirectURL, returnToURL)
 		if err != nil {
 			http.Error(rw, "failed to start auth flow", http.StatusInternalServerError)
 			return

components/public-api-server/pkg/oidc/service.go

@@ -69,14 +69,12 @@ func NewService(sessionServiceAddress string, dbConn *gorm.DB, cipher db.Cipher,
 	}
 }
 
-func (s *Service) GetStartParams(config *ClientConfig, redirectURL string) (*StartParams, error) {
+func (s *Service) GetStartParams(config *ClientConfig, redirectURL string, returnToURL string) (*StartParams, error) {
 	// state is supposed to a) be present on client request as cookie header
 	// and b) to be mirrored by the IdP on callback requests.
 	stateParam := StateParam{
 		ClientConfigID: config.ID,
-
-		// TODO(at) read a relative URL from `returnTo` query param of the start request
-		ReturnToURL: "/",
+		ReturnToURL:    returnToURL,
 	}
 	state, err := s.encodeStateParam(stateParam)
 	if err != nil {

components/public-api-server/pkg/oidc/service_test.go

@@ -43,7 +43,7 @@ func TestGetStartParams(t *testing.T) {
 		},
 	}
 
-	params, err := service.GetStartParams(config, redirectURL)
+	params, err := service.GetStartParams(config, redirectURL, "/")
 
 	require.NoError(t, err)
 	require.NotNil(t, params.Nonce)