kms: rename kms to keyservice

In the light of extending our eKMS support it will be helpful
to have a tighter use of the word "KMS".
KMS should refer to the actual component that manages keys.
The keyservice, also called KMS in the constellation code,
does not manage keys itself. It talks to a KMS backend,
which in turn does the actual key management.

keyservice/internal/server/server_test.go

@@ -0,0 +1,71 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package server
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/edgelesssys/constellation/v2/internal/logger"
+	"github.com/edgelesssys/constellation/v2/keyservice/keyserviceproto"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/goleak"
+)
+
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}
+
+func TestGetDataKey(t *testing.T) {
+	assert := assert.New(t)
+	require := require.New(t)
+
+	log := logger.NewTest(t)
+
+	kms := &stubKMS{derivedKey: []byte{0x0, 0x1, 0x2, 0x3, 0x4, 0x5}}
+	api := New(log, kms)
+
+	res, err := api.GetDataKey(context.Background(), &keyserviceproto.GetDataKeyRequest{DataKeyId: "1", Length: 32})
+	require.NoError(err)
+	assert.Equal(kms.derivedKey, res.DataKey)
+
+	// Test no data key id
+	res, err = api.GetDataKey(context.Background(), &keyserviceproto.GetDataKeyRequest{Length: 32})
+	require.Error(err)
+	assert.Nil(res)
+
+	// Test no / zero key length
+	res, err = api.GetDataKey(context.Background(), &keyserviceproto.GetDataKeyRequest{DataKeyId: "1"})
+	require.Error(err)
+	assert.Nil(res)
+
+	// Test derive key error
+	api = New(log, &stubKMS{deriveKeyErr: errors.New("error")})
+	res, err = api.GetDataKey(context.Background(), &keyserviceproto.GetDataKeyRequest{DataKeyId: "1", Length: 32})
+	assert.Error(err)
+	assert.Nil(res)
+}
+
+type stubKMS struct {
+	masterKey    []byte
+	derivedKey   []byte
+	deriveKeyErr error
+}
+
+func (c *stubKMS) CreateKEK(ctx context.Context, keyID string, kek []byte) error {
+	c.masterKey = kek
+	return nil
+}
+
+func (c *stubKMS) GetDEK(ctx context.Context, kekID string, dekID string, dekSize int) ([]byte, error) {
+	if c.deriveKeyErr != nil {
+		return nil, c.deriveKeyErr
+	}
+	return c.derivedKey, nil
+}