From 92383e94cf7ac37c41c19eea67d50ce34fc0e702 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Harasimowicz?= <dev@harnash.eu>
Date: Tue, 11 Jan 2022 18:59:26 +0100
Subject: [PATCH] PLATFORM-6607| add configurable session refresh time window

---
 driver/config/config.go   |  5 +++++
 embedx/config.schema.json | 12 ++++++++++++
 session/handler.go        |  7 ++++---
 session/session.go        |  8 ++++++++
 session/session_test.go   |  9 +++++++++
 5 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/driver/config/config.go b/driver/config/config.go
index 2a23ceaacc48..b9c40dbeac63 100644
--- a/driver/config/config.go
+++ b/driver/config/config.go
@@ -96,6 +96,7 @@ const (
 	ViperKeySessionPersistentCookie                          = "session.cookie.persistent"
 	ViperKeySessionWhoAmIAAL                                 = "session.whoami.required_aal"
 	ViperKeySessionWhoAmIRefresh                             = "session.whoami.refresh"
+	ViperKeySessionRefreshTimeWindow                         = "session.refresh_time_window"
 	ViperKeyCookieSameSite                                   = "cookies.same_site"
 	ViperKeyCookieDomain                                     = "cookies.domain"
 	ViperKeyCookiePath                                       = "cookies.path"
@@ -1034,6 +1035,10 @@ func (p *Config) SessionWhoAmIRefresh() bool {
 	return p.p.Bool(ViperKeySessionWhoAmIRefresh)
 }
 
+func (p *Config) SessionRefreshTimeWindow() time.Duration {
+	return p.p.DurationF(ViperKeySessionRefreshTimeWindow, p.SessionLifespan()/2)
+}
+
 func (p *Config) SelfServiceSettingsRequiredAAL() string {
 	return p.p.String(ViperKeySelfServiceSettingsRequiredAAL)
 }
diff --git a/embedx/config.schema.json b/embedx/config.schema.json
index 24f0e3d5033d..dd9626c54087 100644
--- a/embedx/config.schema.json
+++ b/embedx/config.schema.json
@@ -2174,6 +2174,18 @@
             }
           },
           "additionalProperties": false
+        },
+        "refresh_time_window": {
+          "title": "Session refresh time window",
+          "description": "Time window when session can be refreshed to avoid excess refreshes. It is calculated as duration from the session expiration time.",
+          "type": "string",
+          "pattern": "^[0-9]+(ns|us|ms|s|m|h)$",
+          "default": "12h",
+          "examples": [
+            "1h",
+            "1m",
+            "1s"
+          ]
         }
       }
     },
diff --git a/session/handler.go b/session/handler.go
index 7f317ab52114..0929dcaa935d 100644
--- a/session/handler.go
+++ b/session/handler.go
@@ -170,7 +170,8 @@ func (h *Handler) whoami(w http.ResponseWriter, r *http.Request, ps httprouter.P
 	}
 
 	var aalErr *ErrAALNotSatisfied
-	if err := h.r.SessionManager().DoesSessionSatisfy(r, s, h.r.Config(r.Context()).SessionWhoAmIAAL()); errors.As(err, &aalErr) {
+	c := h.r.Config(r.Context())
+	if err := h.r.SessionManager().DoesSessionSatisfy(r, s, c.SessionWhoAmIAAL()); errors.As(err, &aalErr) {
 		h.r.Audit().WithRequest(r).WithError(err).Info("Session was found but AAL is not satisfied for calling this endpoint.")
 		h.r.Writer().WriteError(w, r, err)
 		return
@@ -182,8 +183,8 @@ func (h *Handler) whoami(w http.ResponseWriter, r *http.Request, ps httprouter.P
 
 	// Refresh session if param was true
 	refresh := r.URL.Query().Get("refresh")
-	if h.r.Config(r.Context()).SessionWhoAmIRefresh() && refresh == "true" {
-		if err := h.r.SessionPersister().UpsertSession(r.Context(), s.Refresh(h.r.Config(r.Context()))); err != nil {
+	if c.SessionWhoAmIRefresh() && refresh == "true" && s.CanBeRefreshed(c) {
+		if err := h.r.SessionPersister().UpsertSession(r.Context(), s.Refresh(c)); err != nil {
 			h.r.Writer().WriteError(w, r, err)
 			return
 		}
diff --git a/session/session.go b/session/session.go
index 96d9be4909c3..d842a3c7d6af 100644
--- a/session/session.go
+++ b/session/session.go
@@ -24,6 +24,10 @@ type lifespanProvider interface {
 	SessionLifespan() time.Duration
 }
 
+type refreshWindowProvider interface {
+	SessionRefreshTimeWindow() time.Duration
+}
+
 // A Session
 //
 // swagger:model session
@@ -161,6 +165,10 @@ func (s *Session) Refresh(c lifespanProvider) *Session {
 	return s
 }
 
+func (s *Session) CanBeRefreshed(c refreshWindowProvider) bool {
+	return time.Now().Add(c.SessionRefreshTimeWindow()).After(s.ExpiresAt)
+}
+
 func (s *Session) IsActive() bool {
 	return s.Active && s.ExpiresAt.After(time.Now()) && (s.Identity == nil || s.Identity.IsActive())
 }
diff --git a/session/session_test.go b/session/session_test.go
index 63bed7b20324..b5e2ee317b71 100644
--- a/session/session_test.go
+++ b/session/session_test.go
@@ -60,6 +60,15 @@ func TestSession(t *testing.T) {
 		assert.Empty(t, s.AuthenticatedAt)
 	})
 
+	t.Run("case=session refresh", func(t *testing.T) {
+		s := session.NewInactiveSession()
+		assert.False(t, s.CanBeRefreshed(conf), "fresh session is not refreshable")
+
+		s.ExpiresAt = time.Now().Add(13 * time.Hour)
+		assert.True(t, s.CanBeRefreshed(conf), "session is refreshable after 13hrs")
+
+	})
+
 	t.Run("case=aal", func(t *testing.T) {
 		for _, tc := range []struct {
 			d        string