[#30] add object name resolving

Signed-off-by: Pavel Pogodaev <p.pogodaev@yadro.com>

internal/frostfs/services/tree_client_grpc_signature.go

@@ -0,0 +1,29 @@
+/*REMOVE THIS AFTER SIGNATURE WILL BE AVAILABLE IN TREE CLIENT FROM FROSTFS NODE*/
+package services
+
+import (
+	crypto "git.frostfs.info/TrueCloudLab/frostfs-crypto"
+	"google.golang.org/protobuf/proto"
+)
+
+func (c *ServiceClientGRPC) signData(buf []byte, f func(key, sign []byte)) error {
+	// crypto package should not be used outside of API libraries (see neofs-node#491).
+	// For now tree service does not include into SDK Client nor SDK Pool, so there is no choice.
+	// When SDK library adopts Tree service client, this should be dropped.
+	sign, err := crypto.Sign(&c.key.PrivateKey, buf)
+	if err != nil {
+		return err
+	}
+
+	f(c.key.PublicKey().Bytes(), sign)
+	return nil
+}
+
+func (c *ServiceClientGRPC) signRequest(requestBody proto.Message, f func(key, sign []byte)) error {
+	buf, err := proto.Marshal(requestBody)
+	if err != nil {
+		return err
+	}
+
+	return c.signData(buf, f)
+}