判断是否来自搜索引擎链接

/// <summary>
/// 判断是否来自搜索引擎链接
/// </summary>
/// <returns>是否来自搜索引擎链接</returns>
public static bool IsSearchEnginesGet()
{
if (HttpContext.Current.Request.UrlReferrer == null)
{
  return false;
}
   string[] SearchEngine = {"google", "yahoo", "msn", "baidu", "sogou", "sohu", "sina", "163", "lycos", "tom", "yisou", "iask", "soso", "gougou", "zhongsou"};
        string tmpReferrer = HttpContext.Current.Request.UrlReferrer.ToString().ToLower();
        for (int i = 0; i < SearchEngine.Length; i++)
        {
                 if (tmpReferrer.IndexOf(SearchEngine[i]) >= 0)
                 {
                           return true;
                 }
        }
        return false;
}