web系统安全运营之基础- 基于DFA算法的高性能的敏感词，脏词的检测过滤算法类(c#).

【概述】做好一个web系统的安全运维，除了常规的防注入，防入侵等，还有一个检测并过滤敏感词，脏词.. 这件事做得不好，轻则导致一场投诉或纠纷，重则导致产品被勒令关闭停运。

废话少说，先看下代码,可以拿过去直接使用。

  1 using Microsoft.VisualBasic;
  2 using System;
  3 using System.Collections.Generic;
  4 using System.IO;
  5 using System.Linq;
  6 using System.Text;
  7 
  8 namespace OpenCore.ContentSecurity
  9 {
 10     /// <summary>
 11     /// 功能简介：基于DFA算法的高效率非法关键词检测过滤类(杜绝违法内容)..之所以高效，因为本算法对主输入的字符串，只循环了一次。 无需对词库的每个词进行replace的低效率处理。
 12     /// 开发前参考内容：https://blog.csdn.net/u011966339/article/details/72832197
 13     /// 更新日志：
 14     ///          2020-4-15：加载字典的处理采用静态构造方法中处理，避免频繁加载，提升性能.
 15     ///                          支持多词库文件加载.
 16     ///                          优化了算法的细节，提高健壮性。
 17     /// </summary>
 18     public class SensitiveWordFilter
 19     {
 20         private static string[] dictionaryPathList = null;
 21         /// <summary>
 22         /// 内存词典
 23         /// </summary>
 24         private static WordGroup[] MEMORYLEXICON = new WordGroup[(int)char.MaxValue];
 25         private static object lockObj = new object();
 26         public static void Init(string[] sDictionaryFileName)
 27         {
 28             dictionaryPathList = sDictionaryFileName;
 29             LoadDictionary();
 30         }
 31         public SensitiveWordFilter()
 32         {
 33 
 34         }
 35         private string sourctText = string.Empty;
 36         /// <summary>
 37         /// 检测源
 38         /// </summary>
 39         private string SourctText
 40         {
 41             get { return sourctText; }
 42             set { sourctText = value; }
 43         }
 44         /// <summary>
 45         /// 检测源游标
 46         /// </summary>
 47         private int cursor = 0;
 48         /// <summary>
 49         /// 匹配成功后偏移量
 50         /// </summary>
 51         private int wordlenght = 0;
 52         /// <summary>
 53         /// 检测词游标
 54         /// </summary>
 55         private int nextCursor = 0;
 56         private List<string> illegalWords = new List<string>();
 57         /// <summary>
 58         /// 检测到的非法词集
 59         /// </summary>
 60         public List<string> IllegalWords
 61         {
 62             get { return illegalWords; }
 63         }
 64         /// <summary>
 65         /// 判断是否是中文
 66         /// </summary>
 67         /// <param name="character"></param>
 68         /// <returns></returns>
 69         private bool isCHS(char character)
 70         {
 71             //  中文表意字符的范围 4E00-9FA5
 72             int charVal = (int)character;
 73             return (charVal >= 0x4e00 && charVal <= 0x9fa5);
 74         }
 75         /// <summary>
 76         /// 判断是否是数字
 77         /// </summary>
 78         /// <param name="character"></param>
 79         /// <returns></returns>
 80         private bool isNum(char character)
 81         {
 82             int charVal = (int)character;
 83             return (charVal >= 48 && charVal <= 57);
 84         }
 85         /// <summary>
 86         /// 判断是否是字母
 87         /// </summary>
 88         /// <param name="character"></param>
 89         /// <returns></returns>
 90         private bool isAlphabet(char character)
 91         {
 92             int charVal = (int)character;
 93             return ((charVal >= 97 && charVal <= 122) || (charVal >= 65 && charVal <= 90));
 94         }
 95         /// <summary>
 96         /// 转半角小写的函数(DBC case)
 97         /// </summary>
 98         /// <param name="input">任意字符串</param>
 99         /// <returns>半角字符串</returns>
100         ///<remarks>
101         ///全角空格为12288，半角空格为32
102         ///其他字符半角(33-126)与全角(65281-65374)的对应关系是：均相差65248
103         ///</remarks>
104         private static string ToDBC(string input)
105         {
106             char[] c = input.ToCharArray();
107             for (int i = 0; i < c.Length; i++)
108             {
109                 if (c[i] == 12288)
110                 {
111                     c[i] = (char)32;
112                     continue;
113                 }
114                 if (c[i] > 65280 && c[i] < 65375)
115                     c[i] = (char)(c[i] - 65248);
116             }
117             return new string(c).ToLower();
118         }
119         /// <summary>
120         /// 转换为简体中文
121         /// </summary>
122         /// <param name="sInput"></param>
123         /// <returns></returns>
124         private static string ToSimplifiedChiniese(string sInput)
125         {
126             if (string.IsNullOrEmpty(sInput))
127             {
128                 return string.Empty;
129             }
130             try
131             {
132                 return Strings.StrConv(sInput, VbStrConv.SimplifiedChinese, 0);
133             }
134             catch (Exception ex)
135             {
136 
137             }
138             return sInput;
139         }
140         /// <summary>
141         /// 写入日志(非跨程序域的场景)
142         /// </summary>
143         /// <param name="Msg"></param>
144         private static void SaveLog(string Msg)
145         {
146             string sPath = Path.Combine(AppDomain.CurrentDomain.SetupInformation.ApplicationBase, "SecurityLog");
147             if (!Directory.Exists(sPath))
148             {
149                 Directory.CreateDirectory(sPath);
150             }
151             sPath = string.Format("{0}\{1}", sPath, DateTime.Now.ToString("yyyyMMdd") + ".log");
152             try
153             {
154                 File.AppendAllText(sPath, "[" + DateTime.Now.ToString() + "]" + Msg + "
");
155             }
156             catch
157             {
158             }
159         }
160         /// <summary>
161         /// 加载内存词库
162         /// </summary>
163         private static void LoadDictionary()
164         {
165             if (dictionaryPathList == null || dictionaryPathList.Length == 0)
166             {
167                 SaveLog($"SensitiveWordFilter.LoadDictionary.字典路径配置为空");
168                 return;
169             }
170             foreach (string sFileName in dictionaryPathList)
171             {
172                 if (File.Exists(sFileName) == false)
173                 {
174                     SaveLog($"SensitiveWordFilter.LoadDictionary.路径:{sFileName}不是一个有效的文件");
175                     return;
176                 }
177             }
178             List<string> wordList = new List<string>();
179             Array.Clear(MEMORYLEXICON, 0, MEMORYLEXICON.Length);
180             foreach (string sDictionaryFile in dictionaryPathList)
181             {
182                 string[] words = System.IO.File.ReadAllLines(sDictionaryFile, System.Text.Encoding.Default);
183                 foreach (string word in words)
184                 {
185                     if (string.IsNullOrEmpty(word))
186                         continue;
187                     if (word.Trim().Length == 0)
188                         continue;
189                     string key = ToDBC(word);
190                     wordList.Add(key);
191                     //适配繁体，简体.addbyww@2020-4-15
192                     string key_simple = ToSimplifiedChiniese(key);
193                     if (key_simple != key)
194                     {
195                         wordList.Add(key_simple);
196                     }
197                 }
198             }
199             Comparison<string> cmp = delegate (string key1, string key2)
200             {
201                 return key1.CompareTo(key2);
202             };
203             wordList.Sort(cmp);
204             for (int i = wordList.Count - 1; i > 0; i--)
205             {
206                 if (wordList[i].ToString() == wordList[i - 1].ToString())
207                 {
208                     wordList.RemoveAt(i);
209                 }
210             }
211             foreach (var word in wordList)
212             {
213                 if (word.Length > 0)
214                 {
215                     WordGroup group = MEMORYLEXICON[(int)word[0]];
216                     if (group == null)
217                     {
218                         group = new WordGroup();
219                         MEMORYLEXICON[(int)word[0]] = group;
220                     }
221                     group.Add(word.Substring(1));
222                 }
223             }
224         }
225         /// <summary>
226         /// 检测
227         /// </summary>
228         /// <param name="blackWord"></param>
229         /// <returns></returns>
230         private bool Check(string blackWord)
231         {
232             wordlenght = 0;
233             //检测源下一位游标
234             nextCursor = cursor + 1;
235             bool found = false;
236             //遍历词的每一位做匹配
237             for (int i = 0; i < blackWord.Length; i++)
238             {
239                 //特殊字符偏移游标
240                 int offset = 0;
241                 if (nextCursor >= sourctText.Length)
242                 {
243                     break;
244                 }
245                 else
246                 {
247                     //检测下位字符如果不是汉字 数字 字符 偏移量加1
248                     for (int y = nextCursor; y < sourctText.Length; y++)
249                     {
250 
251                         if (!isCHS(sourctText[y]) && !isNum(sourctText[y]) && !isAlphabet(sourctText[y]))
252                         {
253                             offset++;
254                             //避让特殊字符，下位游标如果>=字符串长度 跳出
255                             if (nextCursor + offset >= sourctText.Length) break;
256                             wordlenght++;
257                         }
258                         else break;
259                     }
260                     if ((int)blackWord[i] == (int)sourctText[nextCursor + offset])
261                     {
262                         found = true;
263                     }
264                     else
265                     {
266                         found = false;
267                         break;
268                     }
269                 }
270                 nextCursor = nextCursor + 1 + offset;
271                 wordlenght++;
272             }
273             return found;
274         }
275         /// <summary>
276         /// 检测并替换敏感词为指定字符。之后返回
277         /// </summary>
278         /// <param name="replaceChar">比如：*</param>
279         public string getDataByFilter(string sSourceInput, char replaceChar)
280         {
281             if (string.IsNullOrEmpty(sSourceInput))
282             {
283                 return sSourceInput;
284             }
285             if (MEMORYLEXICON == null || MEMORYLEXICON.Length == 0)
286             {
287                 SaveLog($"SensitiveWordFilter.getDataByFilter.内存字典为空");
288                 return sSourceInput;
289             }
290             //初始化
291             this.cursor = 0;
292             this.wordlenght = 0;
293             this.illegalWords.Clear();
294             this.sourctText = sSourceInput;
295             if (sourctText != string.Empty)
296             {
297                 char[] tempString = sourctText.ToCharArray();
298                 for (int i = 0; i < SourctText.Length; i++)
299                 {
300                     //查询以该字为首字符的词组
301                     WordGroup group = MEMORYLEXICON[(int)ToDBC(SourctText)[i]];
302                     if (group != null)
303                     {
304                         for (int z = 0; z < group.Count(); z++)
305                         {
306                             string word = group.GetWord(z);
307                             if (word.Length == 0 || Check(word))
308                             {
309                                 string blackword = string.Empty;
310                                 for (int pos = 0; pos < wordlenght + 1; pos++)
311                                 {
312                                     blackword += tempString[pos + cursor].ToString();
313                                     tempString[pos + cursor] = replaceChar;
314                                 }
315                                 illegalWords.Add(blackword);
316                                 cursor = cursor + wordlenght;
317                                 i = i + wordlenght;
318                             }
319                         }
320                     }
321                     cursor++;
322                 }
323                 return new string(tempString);
324             }
325             else
326             {
327                 return string.Empty;
328             }
329         }
330     }
331     /// <summary>
332     /// 具有相同首字符的词组集合
333     /// </summary>
334     public class WordGroup
335     {
336         /// <summary>
337         /// 集合
338         /// </summary>
339         private List<string> groupList=new List<string>();
340         public WordGroup()
341         {
342 
343         }
344         /// <summary>
345         /// 添加词
346         /// </summary>
347         /// <param name="word"></param>
348         public void Add(string word)
349         {
350             if (groupList.Contains(word) == false)
351             {
352                 groupList.Add(word);
353             }
354         }
355         /// <summary>
356         /// 获取总数
357         /// </summary>
358         /// <returns></returns>
359         public int Count()
360         {
361             return groupList.Count;
362         }
363         /// <summary>
364         /// 根据下标获取词
365         /// </summary>
366         /// <param name="index"></param>
367         /// <returns></returns>
368         public string GetWord(int index)
369         {
370             return groupList[index];
371         }
372     }
373 }

上面是一个完整的，独立的实现类。下面给一个简单的调用示例:

 1   //全局配置,整个程序只要配置一次即可，后续无需配置
 2             SensitiveWordFilter.Init(new string[] {
 3                  @"C:UsersxDownloads网站需要过滤的敏感词mgck-master暴恐词库.txt",
 4                  @"C:UsersxDownloads网站需要过滤的敏感词mgck-master反动词库.txt",
 5                  @"C:UsersxDownloads网站需要过滤的敏感词mgck-master民生词库.txt",
 6                  @"C:UsersxDownloads网站需要过滤的敏感词mgck-master色情词库.txt",
 7                  @"C:UsersxDownloads网站需要过滤的敏感词mgck-master贪腐词库.txt",
 8                  @"C:UsersxDownloads网站需要过滤的敏感词mgck-master其他词库.txt"
 9             });//注：这里的路径一定要写正确，否则本算法无法生效。
10             //下列可以在多个地方实例化，可以并发执行
11             SensitiveWordFilter wordFilter = new SensitiveWordFilter();
12             Dictionary<string, string> dictTestData = new Dictionary<string, string>();
13             //多测几个示例，看看效果
14             dictTestData["杀^人游戏,有人找一夜q"] = "";//注意，这里本来不是"一夜q",可惜咱们博客园本身也有敏感词检测，无法发布。所以改成q。  如果有人需要测试，请在本地改为词库里的一些内容。！！
15             dictTestData["数学学习课堂"] = "";
16             dictTestData["打击法0功有，法0功毒害大众"] = "";
17             Dictionary<string, string> dictResult = new Dictionary<string, string>();
18             foreach(string sKey in dictTestData.Keys)
19             {
20                 dictResult[sKey] = $"替换后:{wordFilter.getDataByFilter(sKey,'|')},  ------------检测违禁词:{string.Join(",",(wordFilter.IllegalWords==null?new List<string>():wordFilter.IllegalWords))}";
21             }
22             string sResultJson = JsonConverter.SerializeObject(dictResult);
23             Utils.SaveLog(sResultJson);

　最后，给一下打印的结果：

"杀^人游戏,有人找一夜q": 替换后: "杀^人游戏,有人找|||", ------------检测违禁词:一夜q",
"数学学习课堂": 替换后:"数学学习课堂", ------------检测违禁词:,
"打击法0功有，法0功毒害大众": 替换后:"打击|||有，|||毒害大众", ------------检测违禁词:法0功,法0功"

-------------附

词库下载地址：https://codeload.github.com/chason777777/mgck/zip/master