关于使用Request.ServerVariables("HTTP_REFERER")来防止非正常途径访问的问题？

[99dz31]

我在页面中使用HttpAddress=Request.ServerVariables("HTTP_REFERER")和
HttpServerName=Cstr(Request.ServerVariables("SERVER_NAME"))来验证是否从本站来访问
例如:
dim HttpAddress,HttpServerName
HttpAddress=Request.ServerVariables("HTTP_REFERER")
HttpServerName=Cstr(Request.ServerVariables("SERVER_NAME"))

if mid(HttpAddress,8,len(HttpServerName))<>HttpServerName then
response.write "<script language=Javascript>"
response.write "alert('非正常途径访问，请重新登录!')"
response.write "</script>"
response.write "<script language=Javascript>"
response.write "location='UnloadtoLogin.asp';"
response.write "</script>"
response.end
end if


但问题就来了如果我的页面中想使用JAVASCRIPT来跳转的话就不行啊!如我使用:]
if PeonoDBSearch="" then
response.write "<script language=Javascript>"
response.write "alert('自助终端号不能为空,请重试!')"
response.write "</script>"
response.write "<script language=Javascript>"
response.write "location='a.asp';"
response.write "</script>"
response.end
end if

而a页面中就用来第一段的代码所以当我用response.write "location='a.asp';"就会说我非正常进去哦?!!请问我应该怎样来修改啊?