3e68694bdf
Socket binded to INADDR_ANY is not intended to receive unicast traffic before being fully configured, at least dhclient configured with socket-only won't do so on Linux and BSDs (https://github.com/isc-projects/dhcp/blob/v4_4_3/common/socket.c#L1201). We can sometimes receive unicast traffic before being fully configured, it's good, but not always, so we need to set the broadcast flag under some situations. Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>