return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
		}
	} else if err := setKeepAliveIdleAndInterval(c.fd, config.Idle, config.Interval); err != nil {
		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	if err := setKeepAliveCount(c.fd, config.Count); err != nil {

			return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
		}
		if err := setKeepAliveCount(c.fd, config.Count); err != nil {
			return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
		}
	} else if err := setKeepAliveIdleAndIntervalAndCount(c.fd, config.Idle, config.Interval, config.Count); err != nil {

	if index <= 0 {
		return nil, &OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: errInvalidInterfaceIndex}
	}
	ift, err := interfaceTable(index)
	if err != nil {
		return nil, &OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
	}
	ifi, err := interfaceByIndex(ift, index)
	if err != nil {
		err = &OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
	}

		{&OpError{Op: "op", Err: syscall.EADDRNOTAVAIL}, true},
		{&OpError{Op: "op", Err: &os.SyscallError{Syscall: "syscall", Err: syscall.EADDRNOTAVAIL}}, true},

		{syscall.EINVAL, false},
		{&os.SyscallError{Syscall: "syscall", Err: syscall.EINVAL}, false},
		{&OpError{Op: "op", Err: syscall.EINVAL}, false},

	if err != nil {
		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return
}

// WriteToUDP acts like WriteTo but takes a UDPAddr.
func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.writeTo(b, addr)
	if err != nil {

	if err != nil && err != io.EOF {
		err = &OpError{Op: "readfrom", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return n, err
}

// WriteTo implements the io.WriterTo WriteTo method.
func (c *TCPConn) WriteTo(w io.Writer) (int64, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.writeTo(w)
	if err != nil && err != io.EOF {

}

// DialContext connects to the provided address on the provided
// network.
//
// The returned error value may be a net.OpError. When the Op field of
// net.OpError contains "socks", the Source field contains a proxy
// server address and the Addr field contains a command target
// address.
//
// See func Dial of the net package of standard library for a

	var operr error
	err := c.Write(func(s uintptr) bool {
		var written uint32
		var buf syscall.WSABuf
		buf.Buf = &b[0]
		buf.Len = uint32(len(b))
		operr = syscall.WSASend(syscall.Handle(s), &buf, 1, &written, 0, nil, nil)
		return true
	})
	if err != nil {
		return err
	}
	return operr
}

func controlRawConn(c syscall.RawConn, addr Addr) error {
	var operr error
	fn := func(s uintptr) {

	if err != nil {
		t.Fatal(err)
	}

	var operr error
	err = wconn.Write(func(s uintptr) bool {
		_, operr = syscall.Write(syscallDescriptor(s), []byte{'b'})
		return operr != syscall.EAGAIN
	})
	if err != nil {
		t.Fatal(err)
	}
	if operr != nil {
		t.Fatal(err)
	}

	var n int
	buf := make([]byte, 1)
	err = rconn.Read(func(s uintptr) bool {
		n, operr = syscall.Read(syscallDescriptor(s), buf)

// It is the caller's responsibility to close f when finished.
// Closing c does not affect f, and closing f does not affect c.
func FileConn(f *os.File) (c Conn, err error) {
	c, err = fileConn(f)
	if err != nil {
		err = &OpError{Op: "file", Net: "file+net", Source: nil, Addr: fileAddr(f.Name()), Err: err}
	}
	return
}

// FileListener returns a copy of the network listener corresponding
// to the open file f.