content: package com.ruoyi.common.utils.html;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * HTML过滤器，用于去除XSS漏洞隐患。
   *
   * @author ruoyi
   */
  public final class HTMLFilter
  {
      /**
       * regex flag union representing /si modifiers in php
       **/
      private static final int REGEX_FLAGS_SI = Pattern.CASE_INSENSITIVE | Pattern.DOTALL;
      private static final Pattern P_COMMENTS = Pattern.compile("<!--(.*?)-->", Pattern.DOTALL);
      private static final Pattern P_COMMENT = Pattern.compile("^!--(.*)--$", REGEX_FLAGS_SI);
      private static final Pattern P_TAGS = Pattern.compile("<(.*?)>", Pattern.DOTALL);
      private static final Pattern P_END_TAG = Pattern.compile("^/([a-z0-9]+)", REGEX_FLAGS_SI);
      private static final Pattern P_START_TAG = Pattern.compile("^([a-z0-9]+)(.*?)(/?)$", REGEX_FLAGS_SI);
      private static final Pattern P_QUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)=([\"'])(.*?)\\2", REGEX_FLAGS_SI);
      private static final Pattern P_UNQUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)(=)([^\"\\s']+)", REGEX_FLAGS_SI);
      private static final Pattern P_PROTOCOL = Pattern.compile("^([^:]+):", REGEX_FLAGS_SI);
      private static final Pattern P_ENTITY = Pattern.compile("&#(\\d+);?");
      private static final Pattern P_ENTITY_UNICODE = Pattern.compile("&#x([0-9a-f]+);?");
      private static final Pattern P_ENCODE = Pattern.compile("%([0-9a-f]{2});?");
      private static final Pattern P_VALID_ENTITIES = Pattern.compile("&([^&;]*)(?=(;|&|$))");
      private static final Pattern P_VALID_QUOTES = Pattern.compile("(>|^)([^<]+?)(<|$)", Pattern.DOTALL);
      private static final Pattern P_END_ARROW = Pattern.compile("^>");
      private static final Pattern P_BODY_TO_END = Pattern.compile("<([^>]*?)(?=<|$)");
      private static final Pattern P_XML_CONTENT = Pattern.compile("(^|>)([^<]*?)(?=>)");
      private static final Pattern P_STRAY_LEFT_ARROW = Pattern.compile("<([^>]*?)(?=<|$)");
      private static final Pattern P_STRAY_RIGHT_ARROW = Pattern.compile("(^|>)([^<]*?)(?=>)");
      private static final Pattern P_AMP = Pattern.compile("&");
      private static final Pattern P_QUOTE = Pattern.compile("\"");
      private static final Pattern P_LEFT_ARROW = Pattern.compile("<");
      private static final Pattern P_RIGHT_ARROW = Pattern.compile(">");
      private static final Pattern P_BOTH_ARROWS = Pattern.compile("<>");
  
      // @xxx could grow large... maybe use sesat's ReferenceMap
      private static final ConcurrentMap<String, Pattern> P_REMOVE_PAIR_BLANKS = new ConcurrentHashMap<>();
      private static final ConcurrentMap<String, Pattern> P_REMOVE_SELF_BLANKS = new ConcurrentHashMap<>();
  
      /**
       * set of allowed html elements, along with allowed attributes for each element
       **/
      private final Map<String, List<String>> vAllowed;
      /**
       * counts of open tags for each (allowable) html element
       **/
      private final Map<String, Integer> vTagCounts = new HashMap<>();
  
      /**
       * html elements which must always be self-closing (e.g. "<img />")
       **/
      private final String[] vSelfClosingTags;
      /**
       * html elements which must always have separate opening and closing tags (e.g. "<b></b>")
       **/
      private final String[] vNeedClosingTags;
      /**
       * set of disallowed html elements
       **/
      private final String[] vDisallowed;
      /**
       * attributes which should be checked for valid protocols
       **/
      private final String[] vProtocolAtts;
      /**
       * allowed protocols
       **/
      private final String[] vAllowedProtocols;
      /**
       * tags which should be removed if they contain no content (e.g. "<b></b>" or "<b />")
       **/
      private final String[] vRemoveBlanks;
      /**
       * entities allowed within html markup
       **/
      private final String[] vAllowedEntities;
      /**
       * flag determining whether comments are allowed in input String.
       */
      private final boolean stripComment;
      private final boolean encodeQuotes;
      /**
       * flag determining whether to try to make tags when presented with "unbalanced" angle brackets (e.g. "<b text </b>"
       * becomes "<b> text </b>"). If set to false, unbalanced angle brackets will be html escaped.
       */
      private final boolean alwaysMakeTags;
  
      /**
       * Default constructor.
       */
      public HTMLFilter()
      {
          vAllowed = new HashMap<>();
  
          final ArrayList<String> a_atts = new ArrayList<>();
          a_atts.add("href");
          a_atts.add("target");
          vAllowed.put("a", a_atts);
  
          final ArrayList<String> img_atts = new ArrayList<>();
          img_atts.add("src");
          img_atts.add("width");
          img_atts.add("height");
          img_atts.add("alt");
          vAllowed.put("img", img_atts);
  
          final ArrayList<String> no_atts = new ArrayList<>();
          vAllowed.put("b", no_atts);
          vAllowed.put("strong", no_atts);
          vAllowed.put("i", no_atts);
          vAllowed.put("em", no_atts);
  
          vSelfClosingTags = new String[] { "img" };
          vNeedClosingTags = new String[] { "a", "b", "strong", "i", "em" };
          vDisallowed = new String[] {};
          vAllowedProtocols = new String[] { "http", "mailto", "https" }; // no ftp.
          vProtocolAtts = new String[] { "src", "href" };
          vRemoveBlanks = new String[] { "a", "b", "strong", "i", "em" };
          vAllowedEntities = new String[] { "amp", "gt", "lt", "quot" };
          stripComment = true;
          encodeQuotes = true;
          alwaysMakeTags = false;
      }
  
      /**
       * Map-parameter configurable constructor.
       *
       * @param conf map containing configuration. keys match field names.
       */
      @SuppressWarnings("unchecked")
      public HTMLFilter(final Map<String, Object> conf)
      {
  
          assert conf.containsKey("vAllowed") : "configuration requires vAllowed";
          assert conf.containsKey("vSelfClosingTags") : "configuration requires vSelfClosingTags";
          assert conf.containsKey("vNeedClosingTags") : "configuration requires vNeedClosingTags";
          assert conf.containsKey("vDisallowed") : "configuration requires vDisallowed";
          assert conf.containsKey("vAllowedProtocols") : "configuration requires vAllowedProtocols";
          assert conf.containsKey("vProtocolAtts") : "configuration requires vProtocolAtts";
          assert conf.containsKey("vRemoveBlanks") : "configuration requires vRemoveBlanks";
          assert conf.containsKey("vAllowedEntities") : "configuration requires vAllowedEntities";
  
          vAllowed = Collections.unmodifiableMap((HashMap<String, List<String>>) conf.get("vAllowed"));
          vSelfClosingTags = (String[]) conf.get("vSelfClosingTags");
          vNeedClosingTags = (String[]) conf.get("vNeedClosingTags");
          vDisallowed = (String[]) conf.get("vDisallowed");
          vAllowedProtocols = (String[]) conf.get("vAllowedProtocols");
          vProtocolAtts = (String[]) conf.get("vProtocolAtts");
          vRemoveBlanks = (String[]) conf.get("vRemoveBlanks");
          vAllowedEntities = (String[]) conf.get("vAllowedEntities");
          stripComment = conf.containsKey("stripComment") ? (Boolean) conf.get("stripComment") : true;
          encodeQuotes = conf.containsKey("encodeQuotes") ? (Boolean) conf.get("encodeQuotes") : true;
          alwaysMakeTags = conf.containsKey("alwaysMakeTags") ? (Boolean) conf.get("alwaysMakeTags") : true;
      }
  
      private void reset()
      {
          vTagCounts.clear();
      }
  
      // ---------------------------------------------------------------
      // my versions of some PHP library functions
      public static String chr(final int decimal)
      {
          return String.valueOf((char) decimal);
      }
  
      public static String htmlSpecialChars(final String s)
      {
          String result = s;
          result = regexReplace(P_AMP, "&amp;", result);
          result = regexReplace(P_QUOTE, "&quot;", result);
          result = regexReplace(P_LEFT_ARROW, "&lt;", result);
          result = regexReplace(P_RIGHT_ARROW, "&gt;", result);
          return result;
      }
  
      // ---------------------------------------------------------------
  
      /**
       * given a user submitted input String, filter out any invalid or restricted html.
       *
       * @param input text (i.e. submitted by a user) than may contain html
       * @return "clean" version of input, with only valid, whitelisted html elements allowed
       */
      public String filter(final String input)
      {
          reset();
          String s = input;
  
          s = escapeComments(s);
  
          s = balanceHTML(s);
  
          s = checkTags(s);
  
          s = processRemoveBlanks(s);
  
          // s = validateEntities(s);
  
          return s;
      }
  
      public boolean isAlwaysMakeTags()
      {
          return alwaysMakeTags;
      }
  
      public boolean isStripComments()
      {
          return stripComment;
      }
  
      private String escapeComments(final String s)
      {
          final Matcher m = P_COMMENTS.matcher(s);
          final StringBuffer buf = new StringBuffer();
          if (m.find())
          {
              final String match = m.group(1); // (.*?)
              m.appendReplacement(buf, Matcher.quoteReplacement("<!--" + htmlSpecialChars(match) + "-->"));
          }
          m.appendTail(buf);
  
          return buf.toString();
      }
  
      private String balanceHTML(String s)
      {
          if (alwaysMakeTags)
          {
              //
              // try and form html
              //
              s = regexReplace(P_END_ARROW, "", s);
              // 不追加结束标签
              s = regexReplace(P_BODY_TO_END, "<$1>", s);
              s = regexReplace(P_XML_CONTENT, "$1<$2", s);
  
          }
          else
          {
              //
              // escape stray brackets
              //
              s = regexReplace(P_STRAY_LEFT_ARROW, "&lt;$1", s);
              s = regexReplace(P_STRAY_RIGHT_ARROW, "$1$2&gt;<", s);
  
              //
              // the last regexp causes '<>' entities to appear
              // (we need to do a lookahead assertion so that the last bracket can
              // be used in the next pass of the regexp)
              //
              s = regexReplace(P_BOTH_ARROWS, "", s);
          }
  
          return s;
      }
  
      private String checkTags(String s)
      {
          Matcher m = P_TAGS.matcher(s);
  
          final StringBuffer buf = new StringBuffer();
          while (m.find())
          {
              String replaceStr = m.group(1);
              replaceStr = processTag(replaceStr);
              m.appendReplacement(buf, Matcher.quoteReplacement(replaceStr));
          }
          m.appendTail(buf);
  
          // these get tallied in processTag
          // (remember to reset before subsequent calls to filter method)
          final StringBuilder sBuilder = new StringBuilder(buf.toString());
          for (String key : vTagCounts.keySet())
          {
              for (int ii = 0; ii < vTagCounts.get(key); ii++)
              {
                  sBuilder.append("</").append(key).append(">");
              }
          }
          s = sBuilder.toString();
  
          return s;
      }
  
      private String processRemoveBlanks(final String s)
      {
          String result = s;
          for (String tag : vRemoveBlanks)
          {
              if (!P_REMOVE_PAIR_BLANKS.containsKey(tag))
              {
                  P_REMOVE_PAIR_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?></" + tag + ">"));
              }
              result = regexReplace(P_REMOVE_PAIR_BLANKS.get(tag), "", result);
              if (!P_REMOVE_SELF_BLANKS.containsKey(tag))
              {
                  P_REMOVE_SELF_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?/>"));
              }
              result = regexReplace(P_REMOVE_SELF_BLANKS.get(tag), "", result);
          }
  
          return result;
      }
  
      private static String regexReplace(final Pattern regex_pattern, final String replacement, final String s)
      {
          Matcher m = regex_pattern.matcher(s);
          return m.replaceAll(replacement);
      }
  
      private String processTag(final String s)
      {
          // ending tags
          Matcher m = P_END_TAG.matcher(s);
          if (m.find())
          {
              final String name = m.group(1).toLowerCase();
              if (allowed(name))
              {
                  if (false == inArray(name, vSelfClosingTags))
                  {
                      if (vTagCounts.containsKey(name))
                      {
                          vTagCounts.put(name, vTagCounts.get(name) - 1);
                          return "</" + name + ">";
                      }
                  }
              }
          }
  
          // starting tags
          m = P_START_TAG.matcher(s);
          if (m.find())
          {
              final String name = m.group(1).toLowerCase();
              final String body = m.group(2);
              String ending = m.group(3);
  
              // debug( "in a starting tag, name='" + name + "'; body='" + body + "'; ending='" + ending + "'" );
              if (allowed(name))
              {
                  final StringBuilder params = new StringBuilder();
  
                  final Matcher m2 = P_QUOTED_ATTRIBUTES.matcher(body);
                  final Matcher m3 = P_UNQUOTED_ATTRIBUTES.matcher(body);
                  final List<String> paramNames = new ArrayList<>();
                  final List<String> paramValues = new ArrayList<>();
                  while (m2.find())
                  {
                      paramNames.add(m2.group(1)); // ([a-z0-9]+)
                      paramValues.add(m2.group(3)); // (.*?)
                  }
                  while (m3.find())
                  {
                      paramNames.add(m3.group(1)); // ([a-z0-9]+)
                      paramValues.add(m3.group(3)); // ([^\"\\s']+)
                  }
  
                  String paramName, paramValue;
                  for (int ii = 0; ii < paramNames.size(); ii++)
                  {
                      paramName = paramNames.get(ii).toLowerCase();
                      paramValue = paramValues.get(ii);
  
                      // debug( "paramName='" + paramName + "'" );
                      // debug( "paramValue='" + paramValue + "'" );
                      // debug( "allowed? " + vAllowed.get( name ).contains( paramName ) );
  
                      if (allowedAttribute(name, paramName))
                      {
                          if (inArray(paramName, vProtocolAtts))
                          {
                              paramValue = processParamProtocol(paramValue);
                          }
                          params.append(' ').append(paramName).append("=\"").append(paramValue).append("\"");
                      }
                  }
  
                  if (inArray(name, vSelfClosingTags))
                  {
                      ending = " /";
                  }
  
                  if (inArray(name, vNeedClosingTags))
                  {
                      ending = "";
                  }
  
                  if (ending == null || ending.length() < 1)
                  {
                      if (vTagCounts.containsKey(name))
                      {
                          vTagCounts.put(name, vTagCounts.get(name) + 1);
                      }
                      else
                      {
                          vTagCounts.put(name, 1);
                      }
                  }
                  else
                  {
                      ending = " /";
                  }
                  return "<" + name + params + ending + ">";
              }
              else
              {
                  return "";
              }
          }
  
          // comments
          m = P_COMMENT.matcher(s);
          if (!stripComment && m.find())
          {
              return "<" + m.group() + ">";
          }
  
          return "";
      }
  
      private String processParamProtocol(String s)
      {
          s = decodeEntities(s);
          final Matcher m = P_PROTOCOL.matcher(s);
          if (m.find())
          {
              final String protocol = m.group(1);
              if (!inArray(protocol, vAllowedProtocols))
              {
                  // bad protocol, turn into local anchor link instead
                  s = "#" + s.substring(protocol.length() + 1);
                  if (s.startsWith("#//"))
                  {
                      s = "#" + s.substring(3);
                  }
              }
          }
  
          return s;
      }
  
      private String decodeEntities(String s)
      {
          StringBuffer buf = new StringBuffer();
  
          Matcher m = P_ENTITY.matcher(s);
          while (m.find())
          {
              final String match = m.group(1);
              final int decimal = Integer.decode(match).intValue();
              m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
          }
          m.appendTail(buf);
          s = buf.toString();
  
          buf = new StringBuffer();
          m = P_ENTITY_UNICODE.matcher(s);
          while (m.find())
          {
              final String match = m.group(1);
              final int decimal = Integer.valueOf(match, 16).intValue();
              m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
          }
          m.appendTail(buf);
          s = buf.toString();
  
          buf = new StringBuffer();
          m = P_ENCODE.matcher(s);
          while (m.find())
          {
              final String match = m.group(1);
              final int decimal = Integer.valueOf(match, 16).intValue();
              m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
          }
          m.appendTail(buf);
          s = buf.toString();
  
          s = validateEntities(s);
          return s;
      }
  
      private String validateEntities(final String s)
      {
          StringBuffer buf = new StringBuffer();
  
          // validate entities throughout the string
          Matcher m = P_VALID_ENTITIES.matcher(s);
          while (m.find())
          {
              final String one = m.group(1); // ([^&;]*)
              final String two = m.group(2); // (?=(;|&|$))
              m.appendReplacement(buf, Matcher.quoteReplacement(checkEntity(one, two)));
          }
          m.appendTail(buf);
  
          return encodeQuotes(buf.toString());
      }
  
      private String encodeQuotes(final String s)
      {
          if (encodeQuotes)
          {
              StringBuffer buf = new StringBuffer();
              Matcher m = P_VALID_QUOTES.matcher(s);
              while (m.find())
              {
                  final String one = m.group(1); // (>|^)
                  final String two = m.group(2); // ([^<]+?)
                  final String three = m.group(3); // (<|$)
                  // 不替换双引号为&quot;，防止json格式无效 regexReplace(P_QUOTE, "&quot;", two)
                  m.appendReplacement(buf, Matcher.quoteReplacement(one + two + three));
              }
              m.appendTail(buf);
              return buf.toString();
          }
          else
          {
              return s;
          }
      }
  
      private String checkEntity(final String preamble, final String term)
      {
  
          return ";".equals(term) && isValidEntity(preamble) ? '&' + preamble : "&amp;" + preamble;
      }
  
      private boolean isValidEntity(final String entity)
      {
          return inArray(entity, vAllowedEntities);
      }
  
      private static boolean inArray(final String s, final String[] array)
      {
          for (String item : array)
          {
              if (item != null && item.equals(s))
              {
                  return true;
              }
          }
          return false;
      }
  
      private boolean allowed(final String name)
      {
          return (vAllowed.isEmpty() || vAllowed.containsKey(name)) && !inArray(name, vDisallowed);
      }
  
      private boolean allowedAttribute(final String name, final String paramName)
      {
          return allowed(name) && (vAllowed.isEmpty() || vAllowed.get(name).contains(paramName));
      }
  }