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  • ASP.NET 防盗链源码

    /*
    *
    * 防盗链IHttpHandler
    *
    *
    * 增加了对文件关键字的选择(即仅对文件名存在某些关键字或不存在某些关键字进行过滤)
    * 设置web.config中<appSettings>节以下值
    * string eWebapp_NoLink 如果文件名符合该正确表态式将进行过滤(不设置对所有进行过滤)
    * string eWebapp_AllowLink 如果文件名符合该正确表态式将不进行过滤(优先权高于AllowLink,不设置则服从AllowLink)
    * bool eWebapp_ AllowOnlyFile 如果为False,(默认true)则不允许用户直接对该文件进行访问建议为true
    *
    *
    * :)以下设置均可省略,设置只是为了增加灵活性与体验
    * eWebapp_NoLink_Message 错误信息提示:默认为Link From:域名
    * eWebapp_Error_Width 错误信息提示图片宽
    * eWebapp_Error_Height 错误信息提示图片高
    *
    *
    *
    * 垃圾猪 2005-9-11 创建
    * http://ewebapp.net
    */
    using System;
    using System.Web;
    using System.Drawing;
    using System.Drawing.Imaging;
    using System.IO;
    using System.Configuration;
    using System.Text.RegularExpressions;
    namespace eWebapp
    {
    /// <summary>
        /// 防盗链IHttpHandler
        /// 参考http://www.softat.org/archiver/tid-52114.html
        /// 垃圾猪 2005-9-12 修正
        /// </summary>
        public class NoLink : IHttpHandler
    {
    private string eWebapp_NoLink = string.Empty;
    private string eWebapp_AllowLink = string.Empty;
    private bool eWebapp_AllowOnlyFile = true;
    private string eWebapp_NoLink_Message = string.Empty;
    private bool error = false;
    public NoLink()
    {
    //
                // TODO: 在此处添加构造函数逻辑
                //
            }
    public void ProcessRequest(HttpContext context)
    {
    eWebapp_NoLink_Message = ConfigurationSettings.AppSettings["eWebapp_NoLink_Message"];
    string myDomain = string.Empty;
    error = errorLink(context, out myDomain);
    if (Empty(eWebapp_NoLink_Message))
    {
    eWebapp_NoLink_Message = "Link from :" + myDomain;
    }
    if (error)
    {
    //Jpg(context.Response,eWebapp_NoLink_Message);
                    Jpg(context.Response, eWebapp_NoLink_Message);
    }
    else
    {
    Real(context.Response, context.Request);
    }
    }
    public bool IsReusable
    {
    get
    {
    return true;
    }
    }
    /// <summary>
            /// 输出错误信息
            /// </summary>
            /// <param name="Response"></param>
            /// <param name="_word"></param>
            private void Jpg(HttpResponse Response, string _word)
    {
    int myErrorWidth = _word.Length * 15;
    int myErrorHeight = 16;
    try
    {
    int _myErrorWidth = Convert.ToInt32(ConfigurationSettings.AppSettings["eWebapp_Error_Width"]);
    if (_myErrorWidth > 0)
    {
    myErrorWidth = _myErrorWidth;
    }
    }
    catch
    {
    }
    try
    {
    int _myErrorHeight = Convert.ToInt32(ConfigurationSettings.AppSettings["eWebapp_Error_Height"]);
    if (_myErrorHeight > 0)
    {
    myErrorHeight = _myErrorHeight;
    }
    }
    catch
    {
    }
    Bitmap Img = null;
    Graphics g = null;
    MemoryStream ms = null;
    Img = new Bitmap(myErrorWidth, myErrorHeight);
    g = Graphics.FromImage(Img);
    g.Clear(Color.White);
    Font f = new Font("Arial", 9);
    SolidBrush s = new SolidBrush(Color.Red);
    g.DrawString(_word, f, s, 3, 3);
    ms = new MemoryStream();
    Img.Save(ms, ImageFormat.Jpeg);
    Response.ClearContent();
    Response.ContentType = "image/Gif";
    Response.BinaryWrite(ms.ToArray());
    g.Dispose();
    Img.Dispose();
    Response.End();
    }
    /// <summary>
            /// 输出真实文件
            /// </summary>
            /// <param name="response"></param>
            /// <param name="context"></param>
            private void Real(HttpResponse response, HttpRequest request)
    {
    FileInfo file = new System.IO.FileInfo(request.PhysicalPath);
    response.Clear();
    response.AddHeader("Content-Disposition", "filename=" + file.Name);
    response.AddHeader("Content-Length", file.Length.ToString());
    string fileExtension = file.Extension.ToLower();
    //这里选择输出的文件格式
                //可以参考http://ewebapp.cnblogs.com/articles/234756.html增加对更多文件格式的支持.
    
    switch (fileExtension)
    {
    case "mp3":
    response.ContentType = "audio/mpeg3";
    break;
    case "mpeg":
    response.ContentType = "video/mpeg";
    break;
    case "jpg":
    response.ContentType = "image/jpeg";
    break;
    case "bmp":
    response.ContentType = "image/bmp";
    break;
    case "gif":
    response.ContentType = "image/gif";
    break;
    case "doc":
    response.ContentType = "application/msword";
    break;
    case "css":
    response.ContentType = "text/css";
    break;
    default:
    response.ContentType = "application/octet-stream";
    break;
    }
    response.WriteFile(file.FullName);
    response.End();
    }
    /// <summary>
            /// 确认字符串是否为空
            /// </summary>
            /// <param name="_value"></param>
            /// <returns></returns>
            private bool Empty(string _value)
    {
    if (_value == null | _value == string.Empty | _value == "")
    {
    return true;
    }
    else
    {
    return false;
    }
    }
    /// <summary>
            /// 检查是否是非法链接
            /// </summary>
            /// <param name="context"></param>
            /// <param name="_myDomain"></param>
            /// <returns></returns>
            private bool errorLink(HttpContext context, out string _myDomain)
    {
    HttpResponse response = context.Response;
    string myDomain = context.Request.ServerVariables["SERVER_NAME"];
    _myDomain = myDomain;
    string myDomainIp = context.Request.UserHostAddress;
    eWebapp_NoLink = ConfigurationSettings.AppSettings["eWebapp_NoLink"];
    eWebapp_AllowLink = ConfigurationSettings.AppSettings["eWebapp_AllowLink"];
    try
    {
    eWebapp_AllowOnlyFile = Convert.ToBoolean(ConfigurationSettings.AppSettings["eWebapp_AllowOnlyFile"]);
    }
    catch
    {
    eWebapp_AllowOnlyFile = true;
    }
    if (context.Request.UrlReferrer != null)
    {
    //判定referDomain是否存在网站的IP或域名
                    string referDomain = context.Request.UrlReferrer.AbsoluteUri.Replace(context.Request.UrlReferrer.AbsolutePath, "");
    string myPath = context.Request.RawUrl;
    if (referDomain.IndexOf(myDomainIp) >= 0 | referDomain.IndexOf(myDomain) >= 0)
    {
    return false;
    }
    else
    {
    //这里使用正则表达对规则进行匹配
                        try
    {
    Regex myRegex;
    //检查允许匹配
                            if (!Empty(eWebapp_AllowLink))
    {
    myRegex = new Regex(eWebapp_AllowLink);
    if (myRegex.IsMatch(myPath))
    {
    return false;
    }
    }
    //检查禁止匹配
                            if (!Empty(eWebapp_NoLink))
    {
    myRegex = new Regex(eWebapp_NoLink);
    if (myRegex.IsMatch(myPath))
    {
    return true;
    }
    else
    {
    return false;
    }
    }
    return true;
    }
    catch
    {
    //如果匹配出错,链接错误
                            return true;
    }
    }
    }
    else
    {
    //是否允许直接访问文件
                    if (eWebapp_AllowOnlyFile)
    {
    return false;
    }
    else
    {
    return true;
    }
    }
    }
    }
    }
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  • 原文地址:https://www.cnblogs.com/zjoch/p/1422951.html
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