container: add alias method, fix #343

container/config.yml

@@ -1,5 +1,5 @@
 name: "NeoFS Container"
-safemethods: ["count", "containersOf", "get", "owner", "list", "eACL", "getContainerSize", "listContainerSizes", "iterateContainerSizes", "iterateAllContainerSizes", "version"]
+safemethods: ["alias", "count", "containersOf", "get", "owner", "list", "eACL", "getContainerSize", "listContainerSizes", "iterateContainerSizes", "iterateAllContainerSizes", "version"]
 permissions:
   - methods: ["update", "addKey", "transferX",
               "register", "registerTLD", "addRecord", "deleteRecords"]

container/container_contract.go

@@ -417,6 +417,19 @@ func Owner(containerID []byte) []byte {
 	return owner
 }
 
+// Alias method returns a string with an alias of the container if it's set
+// (Null otherwise).
+//
+// If the container doesn't exist, it panics with NotFoundError.
+func Alias(cid []byte) string {
+	ctx := storage.GetReadOnlyContext()
+	owner := getOwnerByID(ctx, cid)
+	if owner == nil {
+		panic(NotFoundError)
+	}
+	return storage.Get(ctx, append([]byte(nnsHasAliasKey), cid...)).(string)
+}
+
 // Count method returns the number of registered containers.
 func Count() int {
 	count := 0

rpc/container/rpcbinding.go

@@ -241,6 +241,11 @@ func New(actor Actor, hash util.Uint160) *Contract {
 	return &Contract{ContractReader{actor, hash}, actor, hash}
 }
 
+// Alias invokes `alias` method of contract.
+func (c *ContractReader) Alias(cid []byte) (string, error) {
+	return unwrap.UTF8String(c.invoker.Call(c.hash, "alias", cid))
+}
+
 // ContainersOf invokes `containersOf` method of contract.
 func (c *ContractReader) ContainersOf(owner []byte) (uuid.UUID, result.Iterator, error) {
 	return unwrap.SessionIterator(c.invoker.Call(c.hash, "containersOf", owner))

tests/container_test.go

@@ -176,6 +176,7 @@ func TestContainerPut(t *testing.T) {
 	cAcc.InvokeFail(t, common.ErrAlphabetWitnessFailed, "put", putArgs...)
 
 	c.Invoke(t, stackitem.Null{}, "put", putArgs...)
+	c.Invoke(t, stackitem.Null{}, "alias", cnt.id[:])
 
 	t.Run("with nice names", func(t *testing.T) {
 		ctrNNS := neotest.CompileFile(t, c.CommitteeHash, nnsPath, path.Join(nnsPath, "config.yml"))
@@ -196,6 +197,7 @@ func TestContainerPut(t *testing.T) {
 		})
 		cNNS := c.CommitteeInvoker(nnsHash)
 		cNNS.Invoke(t, expected, "resolve", "mycnt.neofs", int64(nns.TXT))
+		c.Invoke(t, stackitem.NewByteArray([]byte("mycnt.neofs")), "alias", cnt.id[:])
 
 		t.Run("name is already taken", func(t *testing.T) {
 			c.InvokeFail(t, "name is already taken", "putNamed", putArgs...)