using System;
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using System.Collections;
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using System.Data;
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using System.ServiceModel;
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using System.ServiceModel.Channels;
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namespace CSFrameworkV5.Core.SystemSecurity
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{
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/// <summary>
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/// 用于检测非法攻击WCF的接口,用户连续访问的次数超过指定值抛出异常中断操作
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/// </summary>
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public static class AttackRecorder
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{
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//限制指定时间范围内，当前用户可以访问服务端的次数
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//此值不能太大，否则缓存表记录数较多，记录最后10次访问记录
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private const int LAST_VISIT_COUNT = 20;
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//与 LAST_VISIT_COUNT参数配合使用，比如限制用户3秒内只能访问30次后台的接口
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//时间间隔(秒)，大于此参数值，可能存在恶意攻击行为
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private const int LIMIT_SECONDS = 5;
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//记录访客IP信息及访问记录
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private static Hashtable _VisitorList;
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static AttackRecorder()
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{
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_VisitorList = new Hashtable();
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}
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/// <summary>
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/// 建立访问记录表
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/// </summary>
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/// <returns></returns>
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private static DataTable CreataTable()
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{
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var dt = new DataTable();
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dt.Columns.Add("IP", typeof(string)); //IP地址
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dt.Columns.Add("VisitTime", typeof(DateTime)); //访问时间
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return dt;
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}
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/// <summary>
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/// 取当前用户的IP(客户端)
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/// </summary>
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/// <returns></returns>
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public static string ClientIP
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{
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get
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{
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try
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{
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var context = OperationContext.Current;
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var properties = context.IncomingMessageProperties;
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var endpoint =
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properties[RemoteEndpointMessageProperty.Name] as
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RemoteEndpointMessageProperty;
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return endpoint.Address;
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}
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catch
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{
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return "无法获取IP";
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}
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}
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}
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private static DateTime ToDateTimeEx(object o)
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{
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if (null == o) return DateTime.MinValue;
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try
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{
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var dt = Convert.ToDateTime(o.ToStringEx());
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if (dt < DateTime.Parse("1900-01-01"))
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return DateTime.Parse("1900-01-01");
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else
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return dt;
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}
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catch
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{
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return DateTime.MinValue;
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}
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}
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/// <summary>
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/// 检查用户访问量，如有恶意攻击行为抛出异常
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/// </summary>
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public static void IsAttack()
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{
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var IP = ClientIP; //取客户端IP
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if (_VisitorList.ContainsKey(IP)) //有登记访客
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{
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var dt = _VisitorList[IP] as DataTable;
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dt.Rows.Add(new object[] { IP, DateTime.Now }); //增加访问记录
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//按时间倒序排列，取当前用户最后N次的访问记录
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var rs = dt.Select("IP='" + IP + "'", "VisitTime DESC");
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if (rs.Length >= LAST_VISIT_COUNT)
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{
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var maxTime = ToDateTimeEx(rs[0]["VisitTime"]); //最近一次访问时间
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var minTime =
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ToDateTimeEx(rs[LAST_VISIT_COUNT - 1]["VisitTime"]);
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var ts = maxTime - minTime;
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if (ts.TotalSeconds < LIMIT_SECONDS) //在指定时间内访问次数大于系统参数
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{
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throw new Exception("您的访问频率太高了，请休息下！");
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}
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else
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{
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//删除小于指定时间的访问记录
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var filter = "IP='" + IP + "' AND VisitTime<'" +
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minTime.ToString("yyyy-MM-dd HH:mm:ss") +
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"'";
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rs = dt.Select(filter);
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for (var i = 0; i <= rs.Length - 1; i++)
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dt.Rows.Remove(rs[i]);
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dt.AcceptChanges();
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}
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}
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}
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else //第一次访问服务端，记录IP及访问时间
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{
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var dt = CreataTable();
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dt.Rows.Add(new object[] { IP, DateTime.Now }); //增加访问记录
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dt.AcceptChanges();
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_VisitorList.Add(IP, dt);
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}
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}
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}
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}
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