[#1002] morph: Add UserAllowed method to subnetwork client

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

pkg/morph/client/subnet/clients.go

@@ -0,0 +1,58 @@
+package morphsubnet
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neofs-node/pkg/morph/client"
+)
+
+// UserAllowedPrm groups parameters of UserAllowed method of Subnet contract.
+type UserAllowedPrm struct {
+	args [2]interface{}
+}
+
+// SetID sets identifier of the subnet in a binary NeoFS API protocol format.
+func (x *UserAllowedPrm) SetID(id []byte) {
+	x.args[0] = id
+}
+
+// SetClient sets owner ID of the client that is being checked in a binary NeoFS API protocol format.
+func (x *UserAllowedPrm) SetClient(id []byte) {
+	x.args[1] = id
+}
+
+// UserAllowedRes groups resulting values of UserAllowed method of Subnet contract.
+type UserAllowedRes struct {
+	result bool
+}
+
+// Allowed returns true iff the client is allowed to create containers in the subnet.
+func (x UserAllowedRes) Allowed() bool {
+	return x.result
+}
+
+// UserAllowed checks if the user has access to the subnetwork.
+func (x *Client) UserAllowed(prm UserAllowedPrm) (*UserAllowedRes, error) {
+	args := client.TestInvokePrm{}
+
+	args.SetMethod("userAllowed")
+	args.SetArgs(prm.args[:]...)
+
+	res, err := x.client.TestInvoke(args)
+	if err != nil {
+		return nil, fmt.Errorf("could not make test invoke: %w", err)
+	}
+
+	if len(res) == 0 {
+		return nil, errEmptyResponse
+	}
+
+	result, err := client.BoolFromStackItem(res[0])
+	if err != nil {
+		return nil, err
+	}
+
+	return &UserAllowedRes{
+		result: result,
+	}, nil
+}