用Asp隱藏檔案路徑實現防盜鏈

如果我們知道一個靜態檔案的實際路徑如： http://www.xx.com/download/51windows.pdf ，如果伺服器沒有特別的限制設置，我們就可以毫不費力的把它下載下來！當網站提供51windows.pdf下載時，怎麼樣才能讓下載者無法得到他的實際路徑呢！本文就來介紹如何使用Asp來隱藏檔案的實際下載路徑。

我們在管理網站檔案時，可以把副檔名相同的檔案放在同一個目錄下，取一個比較特別名字，例如放pdf檔目錄為the_pdf_file_s，把下面程式碼另存為down.asp，他的網路路徑為http ://www.xx.com/down.asp，我們就可以用http://www.xx.com/down.asp?FileName=51windows.pdf來下載這個文件了，而且下載者無法看到這個文件實際下載路徑的！在down.asp中我們也可以設定下載檔案是否需要登陸，判斷下載的來源頁是否為外部網站，因此可以做到防止檔案被盜鏈。

範例程式碼：

<% From_url = Cstr(Request.ServerVariables("HTTP_REFERER")) Serv_url = Cstr(Request.ServerVariables("SERVER_NAME")) if mid(From_url,8,len(Serv_url)) <> Serresponse then rite "非法連結！" '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 "無效檔名！" Response.End End if FileExt = MidStrName, In Response. (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/*" '對圖片檔案不出現下載對話框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 '設定pdf類型檔案目錄TrueFileName = "/ the_pdf_file_s/"&FileName end if if lcase(right(FileName,3))="doc" then '設定DOC類型檔案目錄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 '設定影像檔案目錄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 %>