func deviceLoop(dev *device.Device) {
p := fastping.NewPinger()
p.MaxRTT = 5 * time.Second
p.Network("udp")
// resolve IP
// TODO: ipv6 support
ra, err := net.ResolveIPAddr("ip4:icmp", dev.Info.AddrString)
if err != nil {
dev.Warn("ping couldn't resolve the IP address")
return
}
p.AddIPAddr(ra)
// on receive, update last receive time
lastTime := time.Now()
p.OnRecv = func(addr *net.IPAddr, rtt time.Duration) {
dev.Debug("received ICMP packet: addr=%v, rtt=%v", addr, rtt)
if !dev.Online {
dev.Log("now online")
dev.Online = true
}
lastTime = time.Now()
}
// on idle, check if it's been a while
p.OnIdle = func() {
dev.Debug("ICMP idle")
// it's been less than 10 seconds; no big deal
if time.Since(lastTime) < 10*time.Second {
return
}
if dev.Online {
dev.Log("now offline")
dev.Online = false
}
}
// do this continuously
// TODO: if the device is removed or ping is disabled, stop the loop.
dev.Debug("starting ICMP loop")
p.RunLoop()
}
