func Run(listenAddr string) {
	uaddr, _ := net.ResolveUDPAddr("udp", listenAddr)
	conn, _ := net.ListenUDP("udp", uaddr)
	fds, _ := conn.File()
	defer fds.Close()
	fd := int(fds.Fd())
	syscall.SetsockoptInt(fd, syscall.SOL_IP, syscall.IP_TRANSPARENT, 1)
	syscall.SetsockoptInt(fd, syscall.SOL_IP, syscall.IP_RECVORIGDSTADDR, 1)
	for {
		buf := make([]byte, 4096)
		scmBuf := make([]byte, 4096)
		n, scmn, _, src, err := conn.ReadMsgUDP(buf, scmBuf)
		if err != nil {
			log.Printf("[TProxy] Read packet from UDP error: %v\n", err)
			continue
		}
		go handleTProxyUDPPacket(src, n, buf, scmBuf[0:scmn])
	}
}

func handleTProxyUDPPacket(src *net.UDPAddr, n int, buf []byte, scm []byte) {
	msgs, err := syscall.ParseSocketControlMessage(scm)
	...
}

func TestParseSocketControlMessage(t *testing.T) {
        for _, tc := range [][]byte{
                {1, 31, 65, 55, 214, 142, 234, 242, 235, 176, 145, 153, 234, 178, 2, 177, 238, 111, 87, 28, 84, 157, 20, 223, 14, 118, 21, 61, 176, 39, 113, 172},
                {1, 2, 11, 46, 119, 211, 135, 230, 134, 164, 122, 177, 135, 166, 111, 165, 131, 123, 58, 8, 57, 137, 121, 203, 99, 98, 120, 41, 221, 51, 28, 184},
                {1, 15, 176, 48, 199, 181, 23, 145, 22, 211, 111, 200, 23, 209, 255, 210, 19, 12, 170, 127, 169, 254, 233, 188, 243, 21, 232, 94, 77, 68, 140, 207},
                {1, 43, 111, 48, 214, 55, 188, 180, 189, 246, 163, 107, 188, 244, 84, 247, 184, 41, 1, 90, 2, 219, 66, 153, 88, 48, 67, 123, 230, 97, 39, 234},
                {1, 33, 185, 7, 158, 109, 173, 219, 172, 153, 161, 4, 173, 155, 69, 152, 169, 70, 16, 53, 19, 180, 83, 246, 73, 95, 82, 20, 247, 14, 54, 133},
                {1, 62, 215, 26, 79, 218, 126, 130, 127, 192, 142, 142, 126, 194, 150, 193, 122, 31, 195, 108, 192, 237, 128, 175, 154, 6, 129, 77, 36, 87, 229, 220},
                {1, 2, 166, 7, 6, 238, 42, 207, 43, 141, 12, 220, 42, 143, 194, 140, 46, 82, 151, 33, 148, 160, 212, 226, 206, 75, 213, 0, 112, 26, 177, 145},
                {1, 16, 130, 36, 213, 6, 159, 238, 158, 172, 179, 79, 159, 174, 119, 173, 155, 115, 34, 0, 33, 129, 97, 195, 123, 106, 96, 33, 197, 59, 4, 176},
                {1, 12, 50, 4, 187, 36, 199, 216, 198, 154, 141, 105, 199, 152, 47, 155, 195, 69, 122, 54, 121, 183, 57, 245, 35, 92, 56, 23, 157, 13, 92, 134},
        } {
                _, err := syscall.ParseSocketControlMessage(tc)
                if err != nil && err != syscall.EINVAL {
                        t.Errorf("ParseSocketControlMessage: %v", err)
                }
        }
}