Add safesearch test for dnsforward

dnsfilter/dnsfilter.go

@@ -637,6 +637,7 @@ func (d *Dnsfilter) checkSafeSearch(host string) (Result, error) {
 		return Result{}, err
 	}
 
+	res.IP = addrs[0]
 	// The next bug may occurs: LookupIP returns DNS64 mapped ipv4 address with zero-prefix
 	for _, i := range addrs {
 		if ipv4 := i.To4(); ipv4 != nil && len(i) == net.IPv6len {
@@ -645,10 +646,6 @@ func (d *Dnsfilter) checkSafeSearch(host string) (Result, error) {
 		}
 	}
 
-	if res.IP == nil || len(res.IP) == 0 {
-		res.IP = addrs[0]
-	}
-
 	// Cache result
 	err = safeSearchCache.Set(host, res)
 	if err != nil {