all: Implement suture v4-api (#6947)

cmd/strelaysrv/main.go

@@ -3,6 +3,7 @@
 package main
 
 import (
+	"context"
 	"crypto/tls"
 	"flag"
 	"fmt"
@@ -194,7 +195,9 @@ func main() {
 	mapping := mapping{natSvc.NewMapping(nat.TCP, addr.IP, addr.Port)}
 
 	if natEnabled {
-		go natSvc.Serve()
+		ctx, cancel := context.WithCancel(context.Background())
+		go natSvc.Serve(ctx)
+		defer cancel()
 		found := make(chan struct{})
 		mapping.OnChanged(func(_ *nat.Mapping, _, _ []nat.Address) {
 			select {