Function NetDialerWithTCPKeepalive

internal/tcp_keepalive_windows.go:36–54

NetDialerWithTCPKeepalive returns a net.Dialer that enables TCP keepalives on the underlying connection with OS default values for keepalive parameters. TODO: Once https://github.com/golang/go/issues/62254 lands, and the appropriate Go version becomes less than our least supported Go version, we sh

()

// appropriate Go version becomes less than our least supported Go version, we
// should look into using the new API to make things more straightforward.
func NetDialerWithTCPKeepalive() *net.Dialer {
	return &net.Dialer{
		// Setting a negative value here prevents the Go stdlib from overriding
		// the values of TCP keepalive time and interval. It also prevents the
		// Go stdlib from enabling TCP keepalives by default.
		KeepAlive: time.Duration(-1),
		// This method is called after the underlying network socket is created,
		// but before dialing the socket (or calling its connect() method). The
		// combination of unconditionally enabling TCP keepalives here, and
		// disabling the overriding of TCP keepalive parameters by setting the
		// KeepAlive field to a negative value above, results in OS defaults for
		// the TCP keepalive interval and time parameters.
		Control: func(_, _ string, c syscall.RawConn) error {
			return c.Control(func(fd uintptr) {
				windows.SetsockoptInt(windows.Handle(fd), windows.SOL_SOCKET, windows.SO_KEEPALIVE, 1)
			})
		},
	}
}