dedecms添加登录管理认证码的方法

<script language="javascript">
<!--
var closestr=0;
function SetFocus() {
var df = document.form1;
if(df.userid.value == '')
df.userid.focus();
else
df.userid.select();
}
function CheckForm() {
var df = document.form1;
if(df.userid.value == '') {
alert('请输入用户名！');
df.userid.focus();
return false;
}
if(df.pwd.value == '') {
alert('请输入密码！');
df.pwd.focus();
return false;
}
if (df.validate.value == '') {
alert ('请输入您的验证码！');
df.validate.focus();
return(false);
}
if (df.vacodes.value == '') {
alert ('请输入您的认证码！');
df.vacodes.focus();
return(false);
}
}
//-->
</script>

<form name="form1" id="form1" method="post" action="login.php" onsubmit='return CheckForm();'>
<input type="hidden" name="gotopage" value="<?php if(!empty($gotopage)) echo $gotopage;?>" />
<input type="hidden" name="dopost" value="login"/>
<ul>
<li><span>用户名：</span>
<input type="text" name="userid" class="input_out" maxlength="20" style="width:148px;" onfocus="this.className='input_on';this.onmouseout=''" onblur="this.className='input_off';this.onmouseout=function(){this.className='input_out'};" onmousemove="this.className='input_move'" onmouseout="this.className='input_out'"/>
</li>
<li><span>密&nbsp;&nbsp;码：</span>
<input type="password" name="pwd" class="input_out" maxlength="20" style="width:148px;" onfocus="this.className='input_on';this.onmouseout=''" onblur="this.className='input_off';this.onmouseout=function(){this.className='input_out'};" onmousemove="this.className='input_move'" onmouseout="this.className='input_out'"/>
</li>
<li><span>认证码：</span>
<input type="password" name="vacodes" class="input_out" maxlength="20" style="width:148px;" onfocus="this.className='input_on';this.onmouseout=''" onblur="this.className='input_off';this.onmouseout=function(){this.className='input_out'};" onmousemove="this.className='input_move'" onmouseout="this.className='input_out'"/>
</li>
<li><span>验证码：</span>
<input name="validate" type="text" id="vdcode" style="width:50px;text-transform:uppercase;" onfocus="this.className='input_on';this.onmouseout=''" onblur="this.className='input_off';this.onmouseout=function(){this.className='input_out'};" onmousemove="this.className='input_move'" onmouseout="this.className='input_out'" class="input_out"/>
<img id="vdimgck" src="../include/vdimgck.php" alt="看不清？点击更换" align="absmiddle" style="cursor:pointer" onclick="this.src=this.src+'?'"/></li>
<span>&nbsp;</span>
<input name='Submit' type='image' style='width:60px; HEIGHT: 25px;' src='img/submit.gif' width='60' height='27'/>
</li>
</ul>
</form>

if (!emptyempty($userid) && !emptyempty($pwd)) {
$res = $cuserLogin->checkUser($userid, $pwd);
//success
if ($res == 1) {
//里，如下。
if (!emptyempty($userid) && !emptyempty($pwd)) {
$res = $cuserLogin->checkUser($userid, $pwd);
//success
if ($res == 1) { //嵌套到这里面！
$uservacodes = $_POST['vacodes']; //取出vacodes内容放入另一个变量
if ($uservacodes != '认证码自定义') { //自行修改认证码自定义内容！
ResetVdValue();
ShowMsg('认证码不正确!', 'login.php', 0, 1000); //不等于跑这里
die;
} else { //等于就跑这里
$cuserLogin->keepUser();
if (!emptyempty($gotopage)) {
ShowMsg('成功登录，正在转向管理管理主页！', $gotopage);
die;
} else {
$uservacodes = $_POST['vacodes'];
ShowMsg('成功登录，正在转向管理管理主页！', 'index.php');
die;
}
}