status-go/vendor/github.com/koron/go-ssdp/internal/multicast/udp.go

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2023-05-19 20:23:55 +00:00
package multicast
import (
"net"
"sync"
)
type PacketHandler func(net.Addr, []byte) error
type AddrResolver struct {
Addr string
mu sync.RWMutex
udp *net.UDPAddr
err error
}
func (r *AddrResolver) setAddress(addr string) {
r.mu.Lock()
r.Addr = addr
r.udp = nil
r.err = nil
r.mu.Unlock()
}
func (r *AddrResolver) resolve() (*net.UDPAddr, error) {
r.mu.RLock()
if err := r.err; err != nil {
r.mu.RUnlock()
return nil, err
}
if udp := r.udp; udp != nil {
r.mu.RUnlock()
return udp, nil
}
r.mu.RUnlock()
r.mu.Lock()
defer r.mu.Unlock()
r.udp, r.err = net.ResolveUDPAddr("udp4", r.Addr)
return r.udp, r.err
}
var RecvAddrResolver = &AddrResolver{Addr: "224.0.0.1:1900"}
// SetRecvAddrIPv4 updates multicast address where to receive packets.
// This never fail now.
func SetRecvAddrIPv4(addr string) error {
RecvAddrResolver.setAddress(addr)
return nil
}
var sendAddrResolver = &AddrResolver{Addr: "239.255.255.250:1900"}
// SendAddr returns an address to send multicast UDP package.
func SendAddr() (*net.UDPAddr, error) {
return sendAddrResolver.resolve()
}
// SetSendAddrIPv4 updates a UDP address to send multicast packets.
// This never fail now.
func SetSendAddrIPv4(addr string) error {
sendAddrResolver.setAddress(addr)
return nil
}