move SFTPGo package to the internal folder

SFTPGo is a daemon and command line tool, not a library.

The public API are provided by the SDK

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/dataprovider/session.go

@@ -0,0 +1,48 @@
+// Copyright (C) 2019-2022  Nicola Murino
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package dataprovider
+
+import (
+	"errors"
+	"fmt"
+)
+
+// SessionType defines the supported session types
+type SessionType int
+
+// Supported session types
+const (
+	SessionTypeOIDCAuth SessionType = iota + 1
+	SessionTypeOIDCToken
+	SessionTypeResetCode
+)
+
+// Session defines a shared session persisted in the data provider
+type Session struct {
+	Key       string
+	Data      any
+	Type      SessionType
+	Timestamp int64
+}
+
+func (s *Session) validate() error {
+	if s.Key == "" {
+		return errors.New("unable to save a session with an empty key")
+	}
+	if s.Type < SessionTypeOIDCAuth || s.Type > SessionTypeResetCode {
+		return fmt.Errorf("invalid session type: %v", s.Type)
+	}
+	return nil
+}