asp实现禁止搜索引擎蜘蛛访问的代码

<%
function isspider()
dim i,agent,searray
agent="agent:"&lcase(request.servervariables("http_user_agent"))
searray=array("googlebot","baiduspider","sogouspider","yahoo","sosospider")
isspider= false
for i=0 to ubound(searray)
 if (instr(agent,searray(i))>0) then isspider=true
next
end function

function fromse()
dim urlrefer,searray,i
urlrefer="refer:"&lcase(request.servervariables("http_referer"))
fromse= false
if urlrefer="" then fromse= false
searray=array("google","baidu","sogou","yahoo","soso")
for i=0 to ubound(searray)
 if (instr(urlrefer,searray(i))>0) then fromse=true
next
end function

if(isspider()) then
 dim myfso,fileurl,filecon,myfile
 fileurl=server.mappath("images/bg01.gif")
 set myfso=server.createobject("scripting.filesystemobject")
 if myfso.fileexists(fileurl) then
  set myfile=myfso.opentextfile(fileurl, 1)
  filecon=myfile.readall
  response.write(filecon)
  myfile.close
  set myfile=nothing
  set myfso=nothing
  response.end
 end if
end if                
if (fromse()) then
 response.write("<br/>")
 response.end
else
end if
%>