图片、文件防盗链程序
关于图片盗链这个问题,毕竟是自己的劳动成功,很多人不希望别人就那么轻易地偷走了。 这个功能在很多的论坛上都具有,可能是因为盗链的行为太多了吧
反盗链的程序其实很简单,熟悉ASP.NET 应用程序生命周期的话很容易就可以写一个,运用HttpModule在BeginRequest事件中拦截请求就ok了,剩下的工作就是过滤,再过滤!
如果不熟悉HttpModule的话,可以去MSDN上查阅,介绍非常详细,地址:ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.VisualStudio.v80.chs/dv_aspnetcon/html/f1d2910f-61d0-4541-8af8-c3c108ca351f.htm。这里就不废话了
凡是有利必有害,这样做最大的缺点就是增加了系统开销,客户端的每一请求都要过滤一遍,性能自然要打折扣了。不知道哪位朋友有更好的办法,或者优化的方法,一起来探讨探讨。
反盗链的程序其实很简单,熟悉ASP.NET 应用程序生命周期的话很容易就可以写一个,运用HttpModule在BeginRequest事件中拦截请求就ok了,剩下的工作就是过滤,再过滤!
如果不熟悉HttpModule的话,可以去MSDN上查阅,介绍非常详细,地址:ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.VisualStudio.v80.chs/dv_aspnetcon/html/f1d2910f-61d0-4541-8af8-c3c108ca351f.htm。这里就不废话了
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private void Application_BeginRequest(Object source, EventArgs e)
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{
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HttpApplication application = (HttpApplication)source;
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HttpContext context = application.Context;
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bool isSafe = true; //是否合法链接
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string uri = context.Request.Url.AbsolutePath.ToLower();
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if (uri.LastIndexOf(".") > 0 && context.Request.UrlReferrer != null)
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{
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string exp = uri.Substring(uri.LastIndexOf("."));
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//这里是判断文件后缀名是否在排除的文件类型列表之内
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bool isHas = ClassLibrary.RData.RString.StrIsIncUseSC(exp, config.ImgSafeType.Split('|'));
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if (isHas)
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{
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string domainOutter = context.Request.UrlReferrer.Authority.ToLower(); //包含域名和端口
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ArrayList arry = Common.Cache.GetDomainValid();//取系统定义的合法的域名绑定列表
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isSafe = arry.Contains(domainOutter); //判断当前请求的域名是否在合法列表之内
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}
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}
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//下面就是不合法的时候的输出了,如果有默认替代图片则输出,如果没有就生成一个,格式为.gif
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if (!isSafe)
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{
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Bitmap img = null;
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Graphics g = null;
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MemoryStream ms = null;
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try
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{
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string picPath = ClassLibrary.RPath.GetFullDirectory("images/unlawful.gif");
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if (File.Exists(picPath))
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{
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img = new Bitmap(picPath, false);
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}
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else
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{
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img = new Bitmap(64, 64);
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g = Graphics.FromImage(img);
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g.Clear(Color.White);
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Font f = new Font("宋体,黑体,Arial", 9,FontStyle.Bold);
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SolidBrush s = new SolidBrush(Color.Red);
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g.DrawString(Resources.Message.LawlessLink, f, s, 1, 20);
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img.Save(picPath, ImageFormat.Gif);
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}
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ms = new MemoryStream();
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img.Save(ms, ImageFormat.Gif);
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context.Response.ClearContent();
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context.Response.ContentType = "image/Gif";
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context.Response.BinaryWrite(ms.ToArray());
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context.Response.End();
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}
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catch
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{ }
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finally
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{
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if(g != null )
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g.Dispose();
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img.Dispose();
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}
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}
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}
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凡是有利必有害,这样做最大的缺点就是增加了系统开销,客户端的每一请求都要过滤一遍,性能自然要打折扣了。不知道哪位朋友有更好的办法,或者优化的方法,一起来探讨探讨。