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package ice
import (
"net"
"github.com/google/uuid"
"github.com/pion/logging"
"github.com/pion/mdns"
"golang.org/x/net/ipv4"
)
// MulticastDNSMode represents the different Multicast modes ICE can run in
type MulticastDNSMode byte
// MulticastDNSMode enum
const (
// MulticastDNSModeDisabled means remote mDNS candidates will be discarded, and local host candidates will use IPs
MulticastDNSModeDisabled MulticastDNSMode = iota + 1
// MulticastDNSModeQueryOnly means remote mDNS candidates will be accepted, and local host candidates will use IPs
MulticastDNSModeQueryOnly
// MulticastDNSModeQueryAndGather means remote mDNS candidates will be accepted, and local host candidates will use mDNS
MulticastDNSModeQueryAndGather
)
func generateMulticastDNSName() (string, error) {
// https://tools.ietf.org/id/draft-ietf-rtcweb-mdns-ice-candidates-02.html#gathering
// The unique name MUST consist of a version 4 UUID as defined in [RFC4122], followed by “.local”.
u, err := uuid.NewRandom()
return u.String() + ".local", err
}
func createMulticastDNS(mDNSMode MulticastDNSMode, mDNSName string, log logging.LeveledLogger) (*mdns.Conn, MulticastDNSMode, error) {
if mDNSMode == MulticastDNSModeDisabled {
return nil, mDNSMode, nil
}
addr, mdnsErr := net.ResolveUDPAddr("udp4", mdns.DefaultAddress)
if mdnsErr != nil {
return nil, mDNSMode, mdnsErr
}
l, mdnsErr := net.ListenUDP("udp4", addr)
if mdnsErr != nil {
// If ICE fails to start MulticastDNS server just warn the user and continue
log.Errorf("Failed to enable mDNS, continuing in mDNS disabled mode: (%s)", mdnsErr)
return nil, MulticastDNSModeDisabled, nil
}
switch mDNSMode {
case MulticastDNSModeQueryOnly:
conn, err := mdns.Server(ipv4.NewPacketConn(l), &mdns.Config{})
return conn, mDNSMode, err
case MulticastDNSModeQueryAndGather:
conn, err := mdns.Server(ipv4.NewPacketConn(l), &mdns.Config{
LocalNames: []string{mDNSName},
})
return conn, mDNSMode, err
default:
return nil, mDNSMode, nil
}
}
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