support multiple STUN servers

pkg/config/config.go

@@ -15,8 +15,8 @@ type Config struct {
 	MultiNode   bool `yaml:"multi_node"`
 	Development bool `yaml:"development"`
 
-	// Stun server
-	StunServer string `yaml:"stun_server"`
+	// STUN
+	StunServers []string `yaml:"stun_servers"`
 }
 
 func NewConfig(confString string) (*Config, error) {
@@ -26,7 +26,9 @@ func NewConfig(confString string) (*Config, error) {
 		RTCPort:       7881,
 		UDPRangeStart: 10000,
 		UDPRangeEnd:   11000,
-		StunServer:    "stun.l.google.com:19302",
+		StunServers: []string{
+			"stun.l.google.com:19302",
+		},
 	}
 	if confString != "" {
 		yaml.Unmarshal([]byte(confString), conf)

pkg/node/node.go

@@ -1,6 +1,8 @@
 package node
 
 import (
+	"errors"
+
 	"github.com/google/uuid"
 	"github.com/google/wire"
 	"github.com/pion/stun"
@@ -45,7 +47,10 @@ func NewLocalNode(conf *config.Config) (*Node, error) {
 }
 
 func (n *Node) DiscoverNetworkInfo() error {
-	c, err := stun.Dial("udp", n.config.StunServer)
+	if len(n.config.StunServers) == 0 {
+		return errors.New("STUN servers are required but not defined")
+	}
+	c, err := stun.Dial("udp", n.config.StunServers[0])
 	if err != nil {
 		return err
 	}