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package m4p
import (
"log"
"net"
)
// Discoverer magic4pc servers.
type Discoverer struct {
ln *net.UDPConn
device chan DeviceInfo
}
// NewDiscover returns a new Discoverer that listens on the broadcast port.
func NewDiscoverer(broadcastPort int) (*Discoverer, error) {
addr := net.UDPAddr{
Port: broadcastPort,
IP: net.ParseIP("0.0.0.0"),
}
ln, err := net.ListenUDP("udp", &addr)
if err != nil {
panic(err)
}
d := &Discoverer{
ln: ln,
device: make(chan DeviceInfo), // Unbuffered, discard when nobody is listening.
}
go d.discover()
return d, nil
}
func (d *Discoverer) discover() {
var buf [1024]byte
for {
n, addr, err := d.ln.ReadFromUDP(buf[:])
if err != nil {
log.Printf("m4p: Discoverer: discover: read udp packet failed: %v", err)
continue
}
m, err := decode(buf[:n])
if err != nil {
log.Printf("m4p: Discoverer: discover: decode failed: %v", err)
}
switch m.Type {
case Magic4PCAdMessage:
dev := m.DeviceInfo
dev.IPAddr = addr.IP.String()
log.Printf("m4p: Discoverer: discover: found device: %#v", dev)
select {
case d.device <- *dev:
default:
}
default:
log.Printf("m4p: Discoverer: discover: unknown message: %s", m.Type)
}
}
}
// NextDevice returns a newly discovered magic4pc server.
func (d *Discoverer) NextDevice() <-chan DeviceInfo {
return d.device
}
// Close the Discoverer and stop listening for broadcasts.
func (d *Discoverer) Close() error {
return d.ln.Close()
}
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