避免文件被盗链的小本领[Windows安全]

　　我们在管理网站文件时,可以把扩大名一样的文件放在同一个目录下,起一个对比分外名字,比方放pdf文件目录为the_pdf_file_s,把下面代码另存为down.asp,他的网上途径为http://www.xx.com/down.asp,我们便可以用http://www.xx.com/down.asp?FileName=51windows.pdf来下载这个文件了,并且下载者无法看到这个文件实际下载途径的!在down.asp中我们还可以设置下载文件能否需求登陆,判断下载的根源页能否为外部网站,从而可以做到避免文件被盗链.

示例代码:

<%
From_url = Cstr(Request.ServerVariables("HTTP_REFERER"))
Serv_url = Cstr(Request.ServerVariables("SERVER_NAME"))
if mid(From_url,8,len(Serv_url)) <> Serv_url then
response.write "不法链接!" '避免盗链
response.end
end if

if Request.Cookies("Logined")="" then
response.redirect "/login.asp" '需求登陆!
end if
Function GetFileName(longname)'/folder1/folder2/file.asp=>file.asp
while instr(longname,"/")
longname = right(longname,len(longname)-1)
wend
GetFileName = longname
End Function
Dim Stream
Dim Contents
Dim FileName
Dim TrueFileName
Dim FileExt
Const adTypeBinary = 1
FileName = Request.QueryString("FileName")
if FileName = "" Then
Response.Write "无效文件名!"
Response.End
End if
FileExt = Mid(FileName, InStrRev(FileName, ".") + 1)
Select Case UCase(FileExt)
Case "ASP", "ASA", "ASPX", "ASAX", "MDB"
Response.Write "不法操作!"
Response.End
End Select
Response.Clear
if lcase(right(FileName,3))="gif" or lcase(right(FileName,3))="jpg" or lcase(right(FileName,3))="png" then
Response.ContentType = "image/*" '对图象文件不呈现下载对话框
else
Response.ContentType = "application/ms-download"
end if
Response.AddHeader "content-disposition", "attachment; filename=" & GetFileName(Request.QueryString("FileName"))
Set Stream = server.CreateObject("ADODB.Stream")
Stream.Type = adTypeBinary
Stream.Open
if lcase(right(FileName,3))="pdf" then '设置pdf范例文件目录
TrueFileName = "/the_pdf_file_s/"&FileName
end if
if lcase(right(FileName,3))="doc" then '设置DOC范例文件目录
TrueFileName = "/my_D_O_C_file/"&FileName
end if
if lcase(right(FileName,3))="gif" or lcase(right(FileName,3))="jpg" or lcase(right(FileName,3))="png" then
TrueFileName = "/all_images_/"&FileName '设置图象文件目录
end if
Stream.LoadFromFile Server.MapPath(TrueFileName)
While Not Stream.EOS
Response.BinaryWrite Stream.Read(1024 * 64)
Wend
Stream.Close
Set Stream = Nothing
Response.Flush
Response.End
%>

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