Feature: can set custom interface for dns nameserver (#2126)

config/config.go

@@ -477,6 +477,10 @@ func parseNameServer(servers []string) ([]dns.NameServer, error) {
 			return nil, fmt.Errorf("DNS NameServer[%d] format error: %s", idx, err.Error())
 		}
 
+		// parse with specific interface
+		// .e.g 10.0.0.1#en0
+		interfaceName := u.Fragment
+
 		var addr, dnsNetType string
 		switch u.Scheme {
 		case "udp":
@@ -506,8 +510,9 @@ func parseNameServer(servers []string) ([]dns.NameServer, error) {
 		nameservers = append(
 			nameservers,
 			dns.NameServer{
-				Net:  dnsNetType,
-				Addr: addr,
+				Net:       dnsNetType,
+				Addr:      addr,
+				Interface: interfaceName,
 			},
 		)
 	}