用Asp隱藏文件路徑完成防盜鏈

如果我們知道一個(gè)靜態(tài)文件的實(shí)際路徑如：http://www.xx.com/download/51windows.pdf，如果服務(wù)器沒(méi)有作特別的限制設(shè)置，我們就可以毫不費(fèi)力的把它下載下來(lái)！當(dāng)網(wǎng)站提供51windows.pdf下載時(shí)，怎么樣才能讓下載者無(wú)法得到他的實(shí)際路徑呢！本文就來(lái)介紹如何使用Asp來(lái)隱藏文件的實(shí)際下載路徑。

　　我們?cè)诠芾砭W(wǎng)站文件時(shí)，可以把擴(kuò)展名一樣的文件放在同一個(gè)目錄下，起一個(gè)比較特別名字，例如放pdf文件目錄為the_pdf_file_s，把下面代碼另存為down.asp，他的網(wǎng)上路徑為http://www.xx.com/down.asp，我們就可以用http://www.xx.com/down.asp?FileName=51windows.pdf來(lái)下載這個(gè)文件了，而且下載者無(wú)法看到這個(gè)文件實(shí)際下載路徑的！在down.asp中我們還可以設(shè)置下載文件是否需要登陸，判斷下載的來(lái)源頁(yè)是否為外部網(wǎng)站，從而可以做到防止文件被盜鏈。

示例代碼：

<%
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 "非法鏈接！" '防止盜鏈
 response.end
end if

if Request.Cookies("Logined")="" then
 response.redirect "/login.asp" '需要登陸！
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 "無(wú)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 "非法操作！"
        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/*" '對(duì)圖像文件不出現(xiàn)下載對(duì)話框
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 '設(shè)置pdf類型文件目錄
 TrueFileName = "/the_pdf_file_s/"&FileName
end if
if lcase(right(FileName,3))="doc" then '設(shè)置DOC類型文件目錄
 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 '設(shè)置圖像文件目錄
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
%>