中专可以直接上大专么:求动网论坛的防盗链方法～～～

就是showimg.asp
内容如下：
<%
If Dvbbs.BoardID=0 Then
Response.Write("<h1>错误: </h1>参数错误。")
Response.End
End If
Dim filename
filename=Request("filename")
filename=Replace(filename,"..","")
If Request.ServerVariables("HTTP_REFERER")="" Or InStr(Request.ServerVariables("HTTP_REFERER"),Request.ServerVariables("SERVER_NAME"))=0 Or filename="" Then
Call downloadFile(Server.MapPath(Dvbbs.Forum_Info(6)))
Else
If Dvbbs.Forum_Setting(76)="" Or Dvbbs.Forum_Setting(76)="0" Then Dvbbs.Forum_Setting(76)="UploadFile/"
If right(Dvbbs.Forum_Setting(76),1)<>"/" Then Dvbbs.Forum_Setting(76)=Dvbbs.Forum_Setting(76)&"/"
Call downloadFile(Server.MapPath(Dvbbs.Forum_Setting(76)&filename))
End If
Sub downloadFile(strFile)
On error resume next
Server.ScriptTimeOut=999999
Dim S,fso,f,intFilelength,strFilename
strFilename = strFile
Response.Clear
Set s = Server.CreateObject("ADODB.Stream")
s.Open
s.Type = 1
Set fso = Server.CreateObject("Scripting.FileSystemObject")
If Not fso.FileExists(strFilename) Then
Call downloadFile(Server.MapPath(Dvbbs.Forum_Info(6)))
Exit Sub
End If
Set f = fso.GetFile(strFilename)
intFilelength = f.size
s.LoadFromFile(strFilename)
If err Then
Response.Write("<h1>错误: </h1>" & err.Description & "<p>")
Response.End
End If
Set fso=Nothing
Dim Data
Data=s.Read
s.Close
Set s=Nothing
If Response.IsClientConnected Then
If Not (InStr(LCase(f.name),".gif")>0 Or InStr(LCase(f.name),".jpg")>0 Or InStr(LCase(f.name),".jpeg")>0 Or InStr(LCase(f.name),".bmp")>0 )Then
Response.AddHeader "Content-Disposition", "attachment; filename=" & f.name
End If
Response.AddHeader "Content-Length", intFilelength
Response.CharSet = "UTF-8"
Response.ContentType = "application/octet-stream"
Response.BinaryWrite Data
Response.Flush
End If
End Sub
%>

求高手把有用的代码提炼出来～～
是 动网 DVBBS