webrtc: wire full NAT1To1IPs list into core config, replace single-IP workaround (issue #20)

app/webrtc/subsystem.go

@@ -67,14 +67,23 @@ func New(dataCfg config.DataWebRTC, logger log.Logger) (*Subsystem, error) {
 	coreCfg.Enabled = dataCfg.Enable
 	coreCfg.PublicIP = dataCfg.PublicIP
 
-	// If the operator configured multiple NAT1To1 IPs (e.g., dual
+	// Build the NAT1To1IPs list that Pion will use for host candidates.
-	// LAN/public), they take precedence over PublicIP. Wire them
+	// Strategy: merge PublicIP and NAT1To1IPs, deduplicating.
-	// through via PublicIP as the first entry; core/webrtc currently
+	//   - If PublicIP is set it comes first.
-	// reads a single PublicIP, so M2 joins the list with the first
+	//   - Any entries in NAT1To1IPs that differ from PublicIP are appended.
-	// entry winning. (Multi-IP NAT1To1 is an M3 enhancement.)
+	// This replaces the old single-IP workaround and allows dual-homed
-	if len(dataCfg.NAT1To1IPs) > 0 && coreCfg.PublicIP == "" {
+	// servers (e.g., a LAN IP + a public IP) to advertise host candidates
-		coreCfg.PublicIP = dataCfg.NAT1To1IPs[0]
+	// on all interfaces simultaneously.
+	nat1to1IPs := make([]string, 0, len(dataCfg.NAT1To1IPs)+1)
+	if dataCfg.PublicIP != "" {
+		nat1to1IPs = append(nat1to1IPs, dataCfg.PublicIP)
 	}
+	for _, ip := range dataCfg.NAT1To1IPs {
+		if ip != dataCfg.PublicIP {
+			nat1to1IPs = append(nat1to1IPs, ip)
+		}
+	}
+	coreCfg.NAT1To1IPs = nat1to1IPs
 
 	factory, err := corewebrtc.NewPeerFactory(coreCfg)
 	if err != nil {