1 files changed, 24 insertions, 0 deletions
diff --git a/libgo/go/net/sock_linux.go b/libgo/go/net/sock_linux.go
index 2cbc34f24b3..0743843bf28 100644
--- a/libgo/go/net/sock_linux.go
+++ b/libgo/go/net/sock_linux.go
@@ -25,3 +25,27 @@ func maxListenerBacklog() int {
 	}
 	return n
 }
+
+func listenerSockaddr(s, f int, la syscall.Sockaddr, toAddr func(syscall.Sockaddr) Addr) (syscall.Sockaddr, error) {
+	a := toAddr(la)
+	if a == nil {
+		return la, nil
+	}
+	switch v := a.(type) {
+	case *UDPAddr:
+		if v.IP.IsMulticast() {
+			err := setDefaultMulticastSockopts(s)
+			if err != nil {
+				return nil, err
+			}
+			switch f {
+			case syscall.AF_INET:
+				v.IP = IPv4zero
+			case syscall.AF_INET6:
+				v.IP = IPv6unspecified
+			}
+			return v.sockaddr(f)
+		}
+	}
+	return la, nil
+}