Add ice mdns config (#1311)

* Add use_mdns config

* Update config-sample.yaml

Co-authored-by: David Zhao <dz@livekit.io>

Co-authored-by: David Zhao <dz@livekit.io>

config-sample.yaml

@@ -98,6 +98,9 @@ rtc:
   #     - 10.0.0.0/16
   #   excludes:
   #     - 192.168.1.0/24
+  # # Set to true to enable mDNS name candidate. This should be left disabled for most users.
+  # # when enabled, it will impact performance since each PeerConnection will process the same mDNS message independently
+  # use_mdns: true
 
 # when enabled, LiveKit will expose prometheus metrics on :6789/metrics
 # prometheus_port: 6789

pkg/config/config.go

@@ -81,6 +81,7 @@ type RTCConfig struct {
 	Interfaces              InterfacesConfig `yaml:"interfaces"`
 	IPs                     IPsConfig        `yaml:"ips"`
 	EnableLoopbackCandidate bool             `yaml:"enable_loopback_candidate"`
+	UseMDNS                 bool             `yaml:"use_mdns"`
 
 	// Number of packets to buffer for NACK
 	PacketBufferSize int `yaml:"packet_buffer_size,omitempty"`

pkg/rtc/config.go

@@ -90,6 +90,10 @@ func NewWebRTCConfig(conf *config.Config, externalIP string) (*WebRTCConfig, err
 		s.SetIPFilter(filter)
 	}
 
+	if !rtcConf.UseMDNS {
+		s.SetICEMulticastDNSMode(ice.MulticastDNSModeDisabled)
+	}
+
 	var nat1to1IPs []string
 	// force it to the node IPs that the user has set
 	if externalIP != "" && (conf.RTC.UseExternalIP || (conf.RTC.NodeIP != "" && !conf.RTC.NodeIPAutoGenerated)) {