save (#4251)

cmd/downloader/downloader/torrentcfg/torrentcfg.go

 package torrentcfg
 
 import (
+	"fmt"
+	"net"
+	"strings"
 	"time"
 
 	lg "github.com/anacrolix/log"
@@ -57,28 +60,51 @@ func New(snapDir string, verbosity lg.Level, natif nat.Interface, downloadRate,
 	torrentConfig.TorrentPeersHighWater = 500 // default: 500
 	torrentConfig.TorrentPeersLowWater = 50   // default: 50
 
-	torrentConfig.ListenPort = port
 	torrentConfig.Seed = true
 	torrentConfig.DataDir = snapDir
 	torrentConfig.UpnpID = torrentConfig.UpnpID + "leecher"
 
+	torrentConfig.ListenPort = port
+	// check if ipv6 is enabled
+	torrentConfig.DisableIPv6 = true
+	l, err := net.Listen("tcp6", fmt.Sprintf(":%d", port))
+	if err != nil {
+		isDisabled := strings.Contains(err.Error(), "cannot assign requested address") || strings.Contains(err.Error(), "address family not supported by protocol")
+		if !isDisabled {
+			log.Warn("can't enable ipv6", "err", err)
+		}
+	} else {
+		l.Close()
+		torrentConfig.DisableIPv6 = false
+	}
+
 	switch natif.(type) {
 	case nil:
 		// No NAT interface, do nothing.
 	case nat.ExtIP:
 		// ExtIP doesn't block, set the IP right away.
 		ip, _ := natif.ExternalIP()
-		torrentConfig.PublicIp4 = ip
-		log.Info("[torrent] Public IP", "ip", torrentConfig.PublicIp4)
-		// how to set ipv6?
-		//torrentConfig.PublicIp6 = net.ParseIP(ip)
+		if ip != nil {
+			if ip.To4() != nil {
+				torrentConfig.PublicIp4 = ip
+			} else {
+				torrentConfig.PublicIp6 = ip
+			}
+		}
+		log.Info("[torrent] Public IP", "ip", ip)
 
 	default:
 		// Ask the router about the IP. This takes a while and blocks startup,
 		// do it in the background.
 		if ip, err := natif.ExternalIP(); err == nil {
-			torrentConfig.PublicIp4 = ip
-			log.Info("[torrent] Public IP", "ip", torrentConfig.PublicIp4)
+			if ip != nil {
+				if ip.To4() != nil {
+					torrentConfig.PublicIp4 = ip
+				} else {
+					torrentConfig.PublicIp6 = ip
+				}
+			}
+			log.Info("[torrent] Public IP", "ip", ip)
 		}
 	}
 	// rates are divided by 2 - I don't know why it works, maybe bug inside torrent lib accounting