rbd: add kmip encryption type

The Key Management Interoperability Protocol (KMIP)
is an extensible communication protocol
that defines message formats for the manipulation
of cryptographic keys on a key management server.
Ceph-CSI can now be configured to connect to
various KMS using KMIP for encrypting RBD volumes.

https://en.wikipedia.org/wiki/Key_Management_Interoperability_Protocol

Signed-off-by: Rakshith R <rar@redhat.com>

internal/kms/kms_util.go

@@ -0,0 +1,43 @@
+/*
+Copyright 2022 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kms
+
+import "fmt"
+
+// setConfigInt fetches a value from a configuration map and converts it to
+// a integer.
+//
+// If the value is not available, *option is not adjusted and
+// errConfigOptionMissing is returned.
+// In case the value is available, but can not be converted to a string,
+// errConfigOptionInvalid is returned.
+func setConfigInt(option *int, config map[string]interface{}, key string) error {
+	value, ok := config[key]
+	if !ok {
+		return fmt.Errorf("%w: %s", errConfigOptionMissing, key)
+	}
+
+	s, ok := value.(float64)
+	if !ok {
+		return fmt.Errorf("%w: expected float64 for %q, but got %T",
+			errConfigOptionInvalid, key, value)
+	}
+
+	*option = int(s)
+
+	return nil
+}