Prevent JWT login token reuse

management/server/auth/session.go

@@ -0,0 +1,61 @@
+package auth
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/eko/gocache/lib/v4/cache"
+	"github.com/eko/gocache/lib/v4/store"
+)
+
+const (
+	usedTokenKeyPrefix = "jwt-used:"
+	usedTokenMarker    = "1"
+)
+
+var (
+	ErrTokenAlreadyUsed = errors.New("JWT already used")
+	ErrTokenExpired     = errors.New("JWT expired")
+)
+
+type SessionStore struct {
+	cache *cache.Cache[string]
+}
+
+func NewSessionStore(cacheStore store.StoreInterface) *SessionStore {
+	return &SessionStore{cache: cache.New[string](cacheStore)}
+}
+
+// RegisterToken records a JWT until its exp time and rejects reuse.
+func (s *SessionStore) RegisterToken(ctx context.Context, token string, expiresAt time.Time) error {
+	ttl := time.Until(expiresAt)
+	if ttl <= 0 {
+		return ErrTokenExpired
+	}
+
+	key := usedTokenKeyPrefix + hashToken(token)
+	_, err := s.cache.Get(ctx, key)
+	if err == nil {
+		return ErrTokenAlreadyUsed
+	}
+
+	var notFound *store.NotFound
+	if !errors.As(err, &notFound) {
+		return fmt.Errorf("failed to lookup used token entry: %w", err)
+	}
+
+	if err := s.cache.Set(ctx, key, usedTokenMarker, store.WithExpiration(ttl)); err != nil {
+		return fmt.Errorf("failed to store used token entry: %w", err)
+	}
+
+	return nil
+}
+
+func hashToken(token string) string {
+	sum := sha256.Sum256([]byte(token))
+	return hex.EncodeToString(sum[:])
+}