go.patch

diff -ru go-back/src/net/dial.go go/src/net/dial.go
--- go-back/src/net/dial.go	2020-03-14 14:55:07.506350800 +0800
+++ go/src/net/dial.go	2020-03-14 14:38:30.995350900 +0800
@@ -347,6 +347,8 @@
 	return d.DialContext(context.Background(), network, address)
 }
 
+var DialContextDialerHook func(d *Dialer)
+
 // DialContext connects to the address on the named network using
 // the provided context.
 //
@@ -366,6 +368,9 @@
 // See func Dial for a description of the network and address
 // parameters.
 func (d *Dialer) DialContext(ctx context.Context, network, address string) (Conn, error) {
+	if DialContextDialerHook != nil {
+		DialContextDialerHook(d)
+	}
 	if ctx == nil {
 		panic("nil context")
 	}
@@ -519,7 +524,6 @@
 // either the first successful connection, or the first error.
 func (sd *sysDialer) dialSerial(ctx context.Context, ras addrList) (Conn, error) {
 	var firstErr error // The error from the first address is most relevant.
-
 	for i, ra := range ras {
 		select {
 		case <-ctx.Done():
diff -ru go-back/src/net/udpsock.go go/src/net/udpsock.go
--- go-back/src/net/udpsock.go	2020-03-14 14:55:08.235708400 +0800
+++ go/src/net/udpsock.go	2020-03-14 14:36:19.476741700 +0800
@@ -219,6 +219,8 @@
 	return c, nil
 }
 
+var ListenUDPListenConfigHook func(d *ListenConfig)
+
 // ListenUDP acts like ListenPacket for UDP networks.
 //
 // The network must be a UDP network name; see func Dial for details.
@@ -238,6 +240,9 @@
 		laddr = &UDPAddr{}
 	}
 	sl := &sysListener{network: network, address: laddr.String()}
+	if ListenUDPListenConfigHook != nil {
+		ListenUDPListenConfigHook(&sl.ListenConfig)
+	}
 	c, err := sl.listenUDP(context.Background(), laddr)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}