小编典典

HTML Agility Pack条标记不在白名单中

c#

我正在尝试创建一个功能,该功能删除不在白名单中的html标签和属性。我有以下HTML:

<b>first text </b>
<b>second text here
       <a>some text here</a>
 <a>some text here</a>

 </b>
<a>some twxt here</a>

我正在使用HTML敏捷包,到目前为止,我的代码是:

static List<string> WhiteNodeList = new List<string> { "b" };
static List<string> WhiteAttrList = new List<string> { };
static HtmlNode htmlNode;
public static void RemoveNotInWhiteList(out string _output, HtmlNode pNode, List<string> pWhiteList, List<string> attrWhiteList)
{

 // remove all attributes not on white list
 foreach (var item in pNode.ChildNodes)
 {
  item.Attributes.Where(u => attrWhiteList.Contains(u.Name) == false).ToList().ForEach(u => RemoveAttribute(u));

 }

 // remove all html and their innerText and attributes if not on whitelist.
 //pNode.ChildNodes.Where(u => pWhiteList.Contains(u.Name) == false).ToList().ForEach(u => u.Remove());
 //pNode.ChildNodes.Where(u => pWhiteList.Contains(u.Name) == false).ToList().ForEach(u => u.ParentNode.ReplaceChild(ConvertHtmlToNode(u.InnerHtml),u));
 //pNode.ChildNodes.Where(u => pWhiteList.Contains(u.Name) == false).ToList().ForEach(u => u.Remove());

 for (int i = 0; i < pNode.ChildNodes.Count; i++)
 {
  if (!pWhiteList.Contains(pNode.ChildNodes[i].Name))
  {
   HtmlNode _newNode = ConvertHtmlToNode(pNode.ChildNodes[i].InnerHtml);
   pNode.ChildNodes[i].ParentNode.ReplaceChild(_newNode, pNode.ChildNodes[i]);
   if (pNode.ChildNodes[i].HasChildNodes && !string.IsNullOrEmpty(pNode.ChildNodes[i].InnerText.Trim().Replace("\r\n", "")))
   {
    HtmlNode outputNode1 = pNode.ChildNodes[i];
    for (int j = 0; j < pNode.ChildNodes[i].ChildNodes.Count; j++)
    {
     string _childNodeOutput;
     RemoveNotInWhiteList(out _childNodeOutput,
          pNode.ChildNodes[i], WhiteNodeList, WhiteAttrList);
     pNode.ChildNodes[i].ReplaceChild(ConvertHtmlToNode(_childNodeOutput), pNode.ChildNodes[i].ChildNodes[j]);
     i++;
    }
   }
  }
 }

 // Console.WriteLine(pNode.OuterHtml);
 _output = pNode.OuterHtml;
}

private static void RemoveAttribute(HtmlAttribute u)
{
 u.Value = u.Value.ToLower().Replace("javascript", "");
 u.Remove();

}

public static HtmlNode ConvertHtmlToNode(string html)
{
 HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
 doc.LoadHtml(html);
 if (doc.DocumentNode.ChildNodes.Count == 1)
  return doc.DocumentNode.ChildNodes[0];
 else return doc.DocumentNode;
}

我是tryig要实现的输出是

<b>first text </b>
<b>second text here
       some text here
 some text here

 </b>
some twxt here

这意味着我只想保留<b>标签。
我这样做的原因是因为某些用户将cpoy从MS WORD粘贴到ny WYSYWYG html编辑器中。

谢谢。!


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2020-05-19

共1个答案

小编典典

呵呵,显然我ALMOST在某人发的博客文章中找到了答案。

using System.Collections.Generic;
using System.Linq;
using HtmlAgilityPack;

namespace Wayloop.Blog.Core.Markup
{
    public static class HtmlSanitizer
    {
        private static readonly IDictionary<string, string[]> Whitelist;

        static HtmlSanitizer()
        {
            Whitelist = new Dictionary<string, string[]> {
                { "a", new[] { "href" } },
                { "strong", null },
                { "em", null },
                { "blockquote", null },
                };
        }

        public static string Sanitize(string input)
        {
            var htmlDocument = new HtmlDocument();

            htmlDocument.LoadHtml(input);
            SanitizeNode(htmlDocument.DocumentNode);

            return htmlDocument.DocumentNode.WriteTo().Trim();
        }

        private static void SanitizeChildren(HtmlNode parentNode)
        {
            for (int i = parentNode.ChildNodes.Count - 1; i >= 0; i--) {
                SanitizeNode(parentNode.ChildNodes[i]);
            }
        }

        private static void SanitizeNode(HtmlNode node)
        {
            if (node.NodeType == HtmlNodeType.Element) {
                if (!Whitelist.ContainsKey(node.Name)) {
                    node.ParentNode.RemoveChild(node);
                    return;
                }

                if (node.HasAttributes) {
                    for (int i = node.Attributes.Count - 1; i >= 0; i--) {
                        HtmlAttribute currentAttribute = node.Attributes[i];
                        string[] allowedAttributes = Whitelist[node.Name];
                        if (!allowedAttributes.Contains(currentAttribute.Name)) {
                            node.Attributes.Remove(currentAttribute);
                        }
                    }
                }
            }

            if (node.HasChildNodes) {
                SanitizeChildren(node);
            }
        }
    }
}

我从这里得到了HtmlSanitizer 显然,它不会剥离标签,但会一起删除元素。

好的,这是以后需要它的人的解决方案。

public static class HtmlSanitizer
    {
        private static readonly IDictionary<string, string[]> Whitelist;
        private static List<string> DeletableNodesXpath = new List<string>();

        static HtmlSanitizer()
        {
            Whitelist = new Dictionary<string, string[]> {
                { "a", new[] { "href" } },
                { "strong", null },
                { "em", null },
                { "blockquote", null },
                { "b", null},
                { "p", null},
                { "ul", null},
                { "ol", null},
                { "li", null},
                { "div", new[] { "align" } },
                { "strike", null},
                { "u", null},                
                { "sub", null},
                { "sup", null},
                { "table", null },
                { "tr", null },
                { "td", null },
                { "th", null }
                };
        }

        public static string Sanitize(string input)
        {
            if (input.Trim().Length < 1)
                return string.Empty;
            var htmlDocument = new HtmlDocument();

            htmlDocument.LoadHtml(input);            
            SanitizeNode(htmlDocument.DocumentNode);
            string xPath = HtmlSanitizer.CreateXPath();

            return StripHtml(htmlDocument.DocumentNode.WriteTo().Trim(), xPath);
        }

        private static void SanitizeChildren(HtmlNode parentNode)
        {
            for (int i = parentNode.ChildNodes.Count - 1; i >= 0; i--)
            {
                SanitizeNode(parentNode.ChildNodes[i]);
            }
        }

        private static void SanitizeNode(HtmlNode node)
        {
            if (node.NodeType == HtmlNodeType.Element)
            {
                if (!Whitelist.ContainsKey(node.Name))
                {
                    if (!DeletableNodesXpath.Contains(node.Name))
                    {                       
                        //DeletableNodesXpath.Add(node.Name.Replace("?",""));
                        node.Name = "removeableNode";
                        DeletableNodesXpath.Add(node.Name);
                    }
                    if (node.HasChildNodes)
                    {
                        SanitizeChildren(node);
                    }

                    return;
                }

                if (node.HasAttributes)
                {
                    for (int i = node.Attributes.Count - 1; i >= 0; i--)
                    {
                        HtmlAttribute currentAttribute = node.Attributes[i];
                        string[] allowedAttributes = Whitelist[node.Name];
                        if (allowedAttributes != null)
                        {
                            if (!allowedAttributes.Contains(currentAttribute.Name))
                            {
                                node.Attributes.Remove(currentAttribute);
                            }
                        }
                        else
                        {
                            node.Attributes.Remove(currentAttribute);
                        }
                    }
                }
            }

            if (node.HasChildNodes)
            {
                SanitizeChildren(node);
            }
        }

        private static string StripHtml(string html, string xPath)
        {
            HtmlDocument htmlDoc = new HtmlDocument();
            htmlDoc.LoadHtml(html);
            if (xPath.Length > 0)
            {
                HtmlNodeCollection invalidNodes = htmlDoc.DocumentNode.SelectNodes(@xPath);
                foreach (HtmlNode node in invalidNodes)
                {
                    node.ParentNode.RemoveChild(node, true);
                }
            }
            return htmlDoc.DocumentNode.WriteContentTo(); ;
        }

        private static string CreateXPath()
        {
            string _xPath = string.Empty;
            for (int i = 0; i < DeletableNodesXpath.Count; i++)
            {
                if (i != DeletableNodesXpath.Count - 1)
                {
                    _xPath += string.Format("//{0}|", DeletableNodesXpath[i].ToString());
                }
                else _xPath += string.Format("//{0}", DeletableNodesXpath[i].ToString());
            }
            return _xPath;
        }
    }

我重命名了该节点,因为如果必须解析XML名称空间节点,它将在xpath解析时崩溃。

2020-05-19