feat: Add ent-based sqlite3 storage

Signed-off-by: m.nabokikh <maksim.nabokikh@flant.com>

storage/ent/client/utils.go

@@ -0,0 +1,44 @@
+package client
+
+import (
+	"fmt"
+	"hash"
+
+	"github.com/pkg/errors"
+
+	"github.com/dexidp/dex/storage"
+	"github.com/dexidp/dex/storage/ent/db"
+)
+
+func rollback(tx *db.Tx, t string, err error) error {
+	rerr := tx.Rollback()
+	err = convertDBError(t, err)
+
+	if rerr == nil {
+		return err
+	}
+	return errors.Wrapf(err, "rolling back transaction: %v", rerr)
+}
+
+func convertDBError(t string, err error) error {
+	if db.IsNotFound(err) {
+		return storage.ErrNotFound
+	}
+
+	if db.IsConstraintError(err) {
+		return storage.ErrAlreadyExists
+	}
+
+	return fmt.Errorf(t, err)
+}
+
+// compose hashed id from user and connection id to use it as primary key
+// ent doesn't support multi-key primary yet
+// https://github.com/facebook/ent/issues/400
+func offlineSessionID(userID string, connID string, hasher func() hash.Hash) string {
+	h := hasher()
+
+	h.Write([]byte(userID))
+	h.Write([]byte(connID))
+	return fmt.Sprintf("%x", h.Sum(nil))
+}