do_not_reverse_lookup=

static VALUE
bsock_do_not_reverse_lookup_set(VALUE sock, VALUE state)
{
    rb_io_t *fptr;

    rb_secure(4);
    GetOpenFile(sock, fptr);
    if (RTEST(state)) {
        fptr->mode |= FMODE_NOREVLOOKUP;
    }
    else {
        fptr->mode &= ~FMODE_NOREVLOOKUP;
    }
    return sock;
}