Registers socket to receive multicast messages sent to group.
socket must be a gio.types.SocketType.Datagram socket, and must have
been bound to an appropriate interface and port with
gio.socket.Socket.bind.
If iface is null, the system will automatically pick an interface
to bind to based on group.
If source_specific is true, source-specific multicast as defined
in RFC 4604 is used. Note that on older platforms this may fail
with a gio.types.IOErrorEnum.NotSupported error.
Registers socket to receive multicast messages sent to group. socket must be a gio.types.SocketType.Datagram socket, and must have been bound to an appropriate interface and port with gio.socket.Socket.bind.
If iface is null, the system will automatically pick an interface to bind to based on group.
If source_specific is true, source-specific multicast as defined in RFC 4604 is used. Note that on older platforms this may fail with a gio.types.IOErrorEnum.NotSupported error.
To bind to a given source-specific multicast address, use gio.socket.Socket.joinMulticastGroupSsm instead.