[#344] netmap: Support `ExternalAddr` well-known attribute

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

netmap/node_info.go

@@ -371,8 +371,32 @@ const (
 	// attrCapacity is a key to the node attribute that indicates the
 	// total available disk space in Gigabytes.
 	attrCapacity = "Capacity"
+
+	// attrExternalAddr is a key for the attribute storing node external addresses.
+	attrExternalAddr = "ExternalAddr"
+	// sepExternalAddr is a separator for multi-value ExternalAddr attribute.
+	sepExternalAddr = ","
 )
 
+// SetExternalAddresses sets multi-addresses to use
+// to connect to this node from outside.
+//
+// Panics if addr is an empty list.
+func (x *NodeInfo) SetExternalAddresses(addr ...string) {
+	x.SetAttribute(attrExternalAddr, strings.Join(addr, sepExternalAddr))
+}
+
+// ExternalAddresses returns list of multi-addresses to use
+// to connect to this node from outside.
+func (x NodeInfo) ExternalAddresses() []string {
+	a := x.Attribute(attrExternalAddr)
+	if len(a) == 0 {
+		return nil
+	}
+
+	return strings.Split(a, sepExternalAddr)
+}
+
 // NumberOfAttributes returns number of attributes announced by the node.
 //
 // See also SetAttribute.

netmap/node_info_test.go

@@ -45,3 +45,17 @@ func TestNodeInfo_Status(t *testing.T) {
 	require.False(t, n.IsOnline())
 	require.False(t, n.IsOffline())
 }
+
+func TestNodeInfo_ExternalAddr(t *testing.T) {
+	var n NodeInfo
+
+	require.Empty(t, n.ExternalAddresses())
+	require.Panics(t, func() { n.SetExternalAddresses() })
+
+	addr := []string{"1", "2", "3"}
+	n.SetExternalAddresses(addr[0])
+	require.Equal(t, addr[:1], n.ExternalAddresses())
+
+	n.SetExternalAddresses(addr[1:]...)
+	require.Equal(t, addr[1:], n.ExternalAddresses())
+}