Function netstack3_ip::device::join_ip_multicast

pub fn join_ip_multicast<I: IpDeviceIpExt, BC: IpDeviceBindingsContext<I, CC::DeviceId>, CC: IpDeviceConfigurationContext<I, BC>>(
    core_ctx: &mut CC,
    bindings_ctx: &mut BC,
    device_id: &CC::DeviceId,
    multicast_addr: MulticastAddr<I::Addr>,
)

Adds device_id to a multicast group multicast_addr.

Calling join_ip_multicast multiple times is completely safe. A counter will be kept for the number of times join_ip_multicast has been called with the same device_id and multicast_addr pair. To completely leave a multicast group, leave_ip_multicast must be called the same number of times join_ip_multicast has been called for the same device_id and multicast_addr pair. The first time join_ip_multicast is called for a new device and multicast_addr pair, the device will actually join the multicast group.