Merge pull request #197 from bramvbilsen/master

Add Opt-In Functionality for Hashed Session Token Storage

Author: alexedwards

data.go

@@ -3,6 +3,7 @@ package scs
 import (
 	"context"
 	"crypto/rand"
+	"crypto/sha256"
 	"encoding/base64"
 	"fmt"
 	"sort"
@@ -623,6 +624,11 @@ func generateToken() (string, error) {
 	return base64.RawURLEncoding.EncodeToString(b), nil
 }
 
+func hashToken(token string) string {
+	hash := sha256.Sum256([]byte(token))
+	return base64.RawURLEncoding.EncodeToString(hash[:])
+}
+
 type contextKey string
 
 var (
@@ -638,6 +644,9 @@ func generateContextKey() contextKey {
 }
 
 func (s *SessionManager) doStoreDelete(ctx context.Context, token string) (err error) {
+	if s.HashTokenInStore {
+		token = hashToken(token)
+	}
 	c, ok := s.Store.(interface {
 		DeleteCtx(context.Context, string) error
 	})
@@ -648,6 +657,9 @@ func (s *SessionManager) doStoreDelete(ctx context.Context, token string) (err e
 }
 
 func (s *SessionManager) doStoreFind(ctx context.Context, token string) (b []byte, found bool, err error) {
+	if s.HashTokenInStore {
+		token = hashToken(token)
+	}
 	c, ok := s.Store.(interface {
 		FindCtx(context.Context, string) ([]byte, bool, error)
 	})
@@ -658,6 +670,9 @@ func (s *SessionManager) doStoreFind(ctx context.Context, token string) (b []byt
 }
 
 func (s *SessionManager) doStoreCommit(ctx context.Context, token string, b []byte, expiry time.Time) (err error) {
+	if s.HashTokenInStore {
+		token = hashToken(token)
+	}
 	c, ok := s.Store.(interface {
 		CommitCtx(context.Context, string, []byte, time.Time) error
 	})

data_test.go

@@ -198,6 +198,50 @@ func TestSessionManager_Load(T *testing.T) {
 			t.Error("returned context is unexpectedly nil")
 		}
 	})
+
+	T.Run("with token hashing", func(t *testing.T) {
+		s := New()
+		s.HashTokenInStore = true
+		s.IdleTimeout = time.Hour * 24
+
+		expectedToken := "example"
+		expectedExpiry := time.Now().Add(time.Hour)
+
+		initialCtx := context.WithValue(context.Background(), s.contextKey, &sessionData{
+			deadline: expectedExpiry,
+			token:    expectedToken,
+			values: map[string]interface{}{
+				"blah": "blah",
+			},
+			mu: sync.Mutex{},
+		})
+
+		actualToken, actualExpiry, err := s.Commit(initialCtx)
+		if expectedToken != actualToken {
+			t.Errorf("expected token to equal %q, but received %q", expectedToken, actualToken)
+		}
+		if expectedExpiry != actualExpiry {
+			t.Errorf("expected expiry to equal %v, but received %v", expectedExpiry, actualExpiry)
+		}
+		if err != nil {
+			t.Errorf("unexpected error returned: %v", err)
+		}
+
+		retrievedCtx, err := s.Load(context.Background(), expectedToken)
+		if err != nil {
+			t.Errorf("unexpected error returned: %v", err)
+		}
+		retrievedSessionData, ok := retrievedCtx.Value(s.contextKey).(*sessionData)
+		if !ok {
+			t.Errorf("unexpected data in retrieved context")
+		} else if retrievedSessionData.token != expectedToken {
+			t.Errorf("expected token in context's session data data to equal %v, but received %v", expectedToken, retrievedSessionData.token)
+		}
+
+		if err := s.Destroy(retrievedCtx); err != nil {
+			t.Errorf("unexpected error returned: %v", err)
+		}
+	})
 }
 
 func TestSessionManager_Commit(T *testing.T) {
@@ -320,6 +364,35 @@ func TestSessionManager_Commit(T *testing.T) {
 			t.Error("expected error not returned")
 		}
 	})
+
+	T.Run("with token hashing", func(t *testing.T) {
+		s := New()
+		s.HashTokenInStore = true
+		s.IdleTimeout = time.Hour * 24
+
+		expectedToken := "example"
+		expectedExpiry := time.Now().Add(time.Hour)
+
+		ctx := context.WithValue(context.Background(), s.contextKey, &sessionData{
+			deadline: expectedExpiry,
+			token:    expectedToken,
+			values: map[string]interface{}{
+				"blah": "blah",
+			},
+			mu: sync.Mutex{},
+		})
+
+		actualToken, actualExpiry, err := s.Commit(ctx)
+		if expectedToken != actualToken {
+			t.Errorf("expected token to equal %q, but received %q", expectedToken, actualToken)
+		}
+		if expectedExpiry != actualExpiry {
+			t.Errorf("expected expiry to equal %v, but received %v", expectedExpiry, actualExpiry)
+		}
+		if err != nil {
+			t.Errorf("unexpected error returned: %v", err)
+		}
+	})
 }
 
 func TestPut(t *testing.T) {

session.go

@@ -45,6 +45,9 @@ type SessionManager struct {
 	// a function which logs the error and returns a customized HTML error page.
 	ErrorFunc func(http.ResponseWriter, *http.Request, error)
 
+	// HashTokenInStore controls whether or not to store the session token or a hashed version in the store.
+	HashTokenInStore bool
+
 	// contextKey is the key used to set and retrieve the session data from a
 	// context.Context. It's automatically generated to ensure uniqueness.
 	contextKey contextKey