add keepAlive option for udp Listener

common/net/udp/udp.go

@@ -0,0 +1,41 @@
+package udp
+
+import (
+	"io"
+	"net"
+	"syscall"
+)
+
+type Conn interface {
+	net.PacketConn
+	io.Reader
+	io.Writer
+	readUDP
+	writeUDP
+	setBuffer
+	syscallConn
+	remoteAddr
+}
+
+type setBuffer interface {
+	SetReadBuffer(bytes int) error
+	SetWriteBuffer(bytes int) error
+}
+
+type readUDP interface {
+	ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error)
+	ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *net.UDPAddr, err error)
+}
+
+type writeUDP interface {
+	WriteToUDP(b []byte, addr *net.UDPAddr) (int, error)
+	WriteMsgUDP(b, oob []byte, addr *net.UDPAddr) (n, oobn int, err error)
+}
+
+type syscallConn interface {
+	SyscallConn() (syscall.RawConn, error)
+}
+
+type remoteAddr interface {
+	RemoteAddr() net.Addr
+}