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node_modules/xss/lib/cli.js

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+/**
+ * command line tool
+ *
+ * @author Zongmin Lei<leizongmin@gmail.com>
+ */
+
+var xss = require("./");
+var readline = require("readline");
+
+var rl = readline.createInterface({
+  input: process.stdin,
+  output: process.stdout,
+});
+
+console.log('Enter a blank line to do xss(), enter "@quit" to exit.\n');
+
+function take(c, n) {
+  var ret = "";
+  for (var i = 0; i < n; i++) {
+    ret += c;
+  }
+  return ret;
+}
+
+function setPrompt(line) {
+  line = line.toString();
+  rl.setPrompt("[" + line + "]" + take(" ", 5 - line.length));
+  rl.prompt();
+}
+
+setPrompt(1);
+
+var html = [];
+rl.on("line", function (line) {
+  if (line === "@quit") return process.exit();
+  if (line === "") {
+    console.log("");
+    console.log(xss(html.join("\r\n")));
+    console.log("");
+    html = [];
+  } else {
+    html.push(line);
+  }
+  setPrompt(html.length + 1);
+});

node_modules/xss/lib/default.js

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+/**
+ * default settings
+ *
+ * @author Zongmin Lei<leizongmin@gmail.com>
+ */
+
+var FilterCSS = require("cssfilter").FilterCSS;
+var getDefaultCSSWhiteList = require("cssfilter").getDefaultWhiteList;
+var _ = require("./util");
+
+function getDefaultWhiteList() {
+  return {
+    a: ["target", "href", "title"],
+    abbr: ["title"],
+    address: [],
+    area: ["shape", "coords", "href", "alt"],
+    article: [],
+    aside: [],
+    audio: [
+      "autoplay",
+      "controls",
+      "crossorigin",
+      "loop",
+      "muted",
+      "preload",
+      "src",
+    ],
+    b: [],
+    bdi: ["dir"],
+    bdo: ["dir"],
+    big: [],
+    blockquote: ["cite"],
+    br: [],
+    caption: [],
+    center: [],
+    cite: [],
+    code: [],
+    col: ["align", "valign", "span", "width"],
+    colgroup: ["align", "valign", "span", "width"],
+    dd: [],
+    del: ["datetime"],
+    details: ["open"],
+    div: [],
+    dl: [],
+    dt: [],
+    em: [],
+    figcaption: [],
+    figure: [],
+    font: ["color", "size", "face"],
+    footer: [],
+    h1: [],
+    h2: [],
+    h3: [],
+    h4: [],
+    h5: [],
+    h6: [],
+    header: [],
+    hr: [],
+    i: [],
+    img: ["src", "alt", "title", "width", "height", "loading"],
+    ins: ["datetime"],
+    kbd: [],
+    li: [],
+    mark: [],
+    nav: [],
+    ol: [],
+    p: [],
+    pre: [],
+    s: [],
+    section: [],
+    small: [],
+    span: [],
+    sub: [],
+    summary: [],
+    sup: [],
+    strong: [],
+    strike: [],
+    table: ["width", "border", "align", "valign"],
+    tbody: ["align", "valign"],
+    td: ["width", "rowspan", "colspan", "align", "valign"],
+    tfoot: ["align", "valign"],
+    th: ["width", "rowspan", "colspan", "align", "valign"],
+    thead: ["align", "valign"],
+    tr: ["rowspan", "align", "valign"],
+    tt: [],
+    u: [],
+    ul: [],
+    video: [
+      "autoplay",
+      "controls",
+      "crossorigin",
+      "loop",
+      "muted",
+      "playsinline",
+      "poster",
+      "preload",
+      "src",
+      "height",
+      "width",
+    ],
+  };
+}
+
+var defaultCSSFilter = new FilterCSS();
+
+/**
+ * default onTag function
+ *
+ * @param {String} tag
+ * @param {String} html
+ * @param {Object} options
+ * @return {String}
+ */
+function onTag(tag, html, options) {
+  // do nothing
+}
+
+/**
+ * default onIgnoreTag function
+ *
+ * @param {String} tag
+ * @param {String} html
+ * @param {Object} options
+ * @return {String}
+ */
+function onIgnoreTag(tag, html, options) {
+  // do nothing
+}
+
+/**
+ * default onTagAttr function
+ *
+ * @param {String} tag
+ * @param {String} name
+ * @param {String} value
+ * @return {String}
+ */
+function onTagAttr(tag, name, value) {
+  // do nothing
+}
+
+/**
+ * default onIgnoreTagAttr function
+ *
+ * @param {String} tag
+ * @param {String} name
+ * @param {String} value
+ * @return {String}
+ */
+function onIgnoreTagAttr(tag, name, value) {
+  // do nothing
+}
+
+/**
+ * default escapeHtml function
+ *
+ * @param {String} html
+ */
+function escapeHtml(html) {
+  return html.replace(REGEXP_LT, "&lt;").replace(REGEXP_GT, "&gt;");
+}
+
+/**
+ * default safeAttrValue function
+ *
+ * @param {String} tag
+ * @param {String} name
+ * @param {String} value
+ * @param {Object} cssFilter
+ * @return {String}
+ */
+function safeAttrValue(tag, name, value, cssFilter) {
+  // unescape attribute value firstly
+  value = friendlyAttrValue(value);
+
+  if (name === "href" || name === "src") {
+    // filter `href` and `src` attribute
+    // only allow the value that starts with `http://` | `https://` | `mailto:` | `/` | `#`
+    value = _.trim(value);
+    if (value === "#") return "#";
+    if (
+      !(
+        value.substr(0, 7) === "http://" ||
+        value.substr(0, 8) === "https://" ||
+        value.substr(0, 7) === "mailto:" ||
+        value.substr(0, 4) === "tel:" ||
+        value.substr(0, 11) === "data:image/" ||
+        value.substr(0, 6) === "ftp://" ||
+        value.substr(0, 2) === "./" ||
+        value.substr(0, 3) === "../" ||
+        value[0] === "#" ||
+        value[0] === "/"
+      )
+    ) {
+      return "";
+    }
+  } else if (name === "background") {
+    // filter `background` attribute (maybe no use)
+    // `javascript:`
+    REGEXP_DEFAULT_ON_TAG_ATTR_4.lastIndex = 0;
+    if (REGEXP_DEFAULT_ON_TAG_ATTR_4.test(value)) {
+      return "";
+    }
+  } else if (name === "style") {
+    // `expression()`
+    REGEXP_DEFAULT_ON_TAG_ATTR_7.lastIndex = 0;
+    if (REGEXP_DEFAULT_ON_TAG_ATTR_7.test(value)) {
+      return "";
+    }
+    // `url()`
+    REGEXP_DEFAULT_ON_TAG_ATTR_8.lastIndex = 0;
+    if (REGEXP_DEFAULT_ON_TAG_ATTR_8.test(value)) {
+      REGEXP_DEFAULT_ON_TAG_ATTR_4.lastIndex = 0;
+      if (REGEXP_DEFAULT_ON_TAG_ATTR_4.test(value)) {
+        return "";
+      }
+    }
+    if (cssFilter !== false) {
+      cssFilter = cssFilter || defaultCSSFilter;
+      value = cssFilter.process(value);
+    }
+  }
+
+  // escape `<>"` before returns
+  value = escapeAttrValue(value);
+  return value;
+}
+
+// RegExp list
+var REGEXP_LT = /</g;
+var REGEXP_GT = />/g;
+var REGEXP_QUOTE = /"/g;
+var REGEXP_QUOTE_2 = /&quot;/g;
+var REGEXP_ATTR_VALUE_1 = /&#([a-zA-Z0-9]*);?/gim;
+var REGEXP_ATTR_VALUE_COLON = /&colon;?/gim;
+var REGEXP_ATTR_VALUE_NEWLINE = /&newline;?/gim;
+// var REGEXP_DEFAULT_ON_TAG_ATTR_3 = /\/\*|\*\//gm;
+var REGEXP_DEFAULT_ON_TAG_ATTR_4 =
+  /((j\s*a\s*v\s*a|v\s*b|l\s*i\s*v\s*e)\s*s\s*c\s*r\s*i\s*p\s*t\s*|m\s*o\s*c\s*h\s*a):/gi;
+// var REGEXP_DEFAULT_ON_TAG_ATTR_5 = /^[\s"'`]*(d\s*a\s*t\s*a\s*)\:/gi;
+// var REGEXP_DEFAULT_ON_TAG_ATTR_6 = /^[\s"'`]*(d\s*a\s*t\s*a\s*)\:\s*image\//gi;
+var REGEXP_DEFAULT_ON_TAG_ATTR_7 =
+  /e\s*x\s*p\s*r\s*e\s*s\s*s\s*i\s*o\s*n\s*\(.*/gi;
+var REGEXP_DEFAULT_ON_TAG_ATTR_8 = /u\s*r\s*l\s*\(.*/gi;
+
+/**
+ * escape double quote
+ *
+ * @param {String} str
+ * @return {String} str
+ */
+function escapeQuote(str) {
+  return str.replace(REGEXP_QUOTE, "&quot;");
+}
+
+/**
+ * unescape double quote
+ *
+ * @param {String} str
+ * @return {String} str
+ */
+function unescapeQuote(str) {
+  return str.replace(REGEXP_QUOTE_2, '"');
+}
+
+/**
+ * escape html entities
+ *
+ * @param {String} str
+ * @return {String}
+ */
+function escapeHtmlEntities(str) {
+  return str.replace(REGEXP_ATTR_VALUE_1, function replaceUnicode(str, code) {
+    return code[0] === "x" || code[0] === "X"
+      ? String.fromCharCode(parseInt(code.substr(1), 16))
+      : String.fromCharCode(parseInt(code, 10));
+  });
+}
+
+/**
+ * escape html5 new danger entities
+ *
+ * @param {String} str
+ * @return {String}
+ */
+function escapeDangerHtml5Entities(str) {
+  return str
+    .replace(REGEXP_ATTR_VALUE_COLON, ":")
+    .replace(REGEXP_ATTR_VALUE_NEWLINE, " ");
+}
+
+/**
+ * clear nonprintable characters
+ *
+ * @param {String} str
+ * @return {String}
+ */
+function clearNonPrintableCharacter(str) {
+  var str2 = "";
+  for (var i = 0, len = str.length; i < len; i++) {
+    str2 += str.charCodeAt(i) < 32 ? " " : str.charAt(i);
+  }
+  return _.trim(str2);
+}
+
+/**
+ * get friendly attribute value
+ *
+ * @param {String} str
+ * @return {String}
+ */
+function friendlyAttrValue(str) {
+  str = unescapeQuote(str);
+  str = escapeHtmlEntities(str);
+  str = escapeDangerHtml5Entities(str);
+  str = clearNonPrintableCharacter(str);
+  return str;
+}
+
+/**
+ * unescape attribute value
+ *
+ * @param {String} str
+ * @return {String}
+ */
+function escapeAttrValue(str) {
+  str = escapeQuote(str);
+  str = escapeHtml(str);
+  return str;
+}
+
+/**
+ * `onIgnoreTag` function for removing all the tags that are not in whitelist
+ */
+function onIgnoreTagStripAll() {
+  return "";
+}
+
+/**
+ * remove tag body
+ * specify a `tags` list, if the tag is not in the `tags` list then process by the specify function (optional)
+ *
+ * @param {array} tags
+ * @param {function} next
+ */
+function StripTagBody(tags, next) {
+  if (typeof next !== "function") {
+    next = function () {};
+  }
+
+  var isRemoveAllTag = !Array.isArray(tags);
+  function isRemoveTag(tag) {
+    if (isRemoveAllTag) return true;
+    return _.indexOf(tags, tag) !== -1;
+  }
+
+  var removeList = [];
+  var posStart = false;
+
+  return {
+    onIgnoreTag: function (tag, html, options) {
+      if (isRemoveTag(tag)) {
+        if (options.isClosing) {
+          var ret = "[/removed]";
+          var end = options.position + ret.length;
+          removeList.push([
+            posStart !== false ? posStart : options.position,
+            end,
+          ]);
+          posStart = false;
+          return ret;
+        } else {
+          if (!posStart) {
+            posStart = options.position;
+          }
+          return "[removed]";
+        }
+      } else {
+        return next(tag, html, options);
+      }
+    },
+    remove: function (html) {
+      var rethtml = "";
+      var lastPos = 0;
+      _.forEach(removeList, function (pos) {
+        rethtml += html.slice(lastPos, pos[0]);
+        lastPos = pos[1];
+      });
+      rethtml += html.slice(lastPos);
+      return rethtml;
+    },
+  };
+}
+
+/**
+ * remove html comments
+ *
+ * @param {String} html
+ * @return {String}
+ */
+function stripCommentTag(html) {
+  var retHtml = "";
+  var lastPos = 0;
+  while (lastPos < html.length) {
+    var i = html.indexOf("<!--", lastPos);
+    if (i === -1) {
+      retHtml += html.slice(lastPos);
+      break;
+    }
+    retHtml += html.slice(lastPos, i);
+    var j = html.indexOf("-->", i);
+    if (j === -1) {
+      break;
+    }
+    lastPos = j + 3;
+  }
+  return retHtml;
+}
+
+/**
+ * remove invisible characters
+ *
+ * @param {String} html
+ * @return {String}
+ */
+function stripBlankChar(html) {
+  var chars = html.split("");
+  chars = chars.filter(function (char) {
+    var c = char.charCodeAt(0);
+    if (c === 127) return false;
+    if (c <= 31) {
+      if (c === 10 || c === 13) return true;
+      return false;
+    }
+    return true;
+  });
+  return chars.join("");
+}
+
+exports.whiteList = getDefaultWhiteList();
+exports.getDefaultWhiteList = getDefaultWhiteList;
+exports.onTag = onTag;
+exports.onIgnoreTag = onIgnoreTag;
+exports.onTagAttr = onTagAttr;
+exports.onIgnoreTagAttr = onIgnoreTagAttr;
+exports.safeAttrValue = safeAttrValue;
+exports.escapeHtml = escapeHtml;
+exports.escapeQuote = escapeQuote;
+exports.unescapeQuote = unescapeQuote;
+exports.escapeHtmlEntities = escapeHtmlEntities;
+exports.escapeDangerHtml5Entities = escapeDangerHtml5Entities;
+exports.clearNonPrintableCharacter = clearNonPrintableCharacter;
+exports.friendlyAttrValue = friendlyAttrValue;
+exports.escapeAttrValue = escapeAttrValue;
+exports.onIgnoreTagStripAll = onIgnoreTagStripAll;
+exports.StripTagBody = StripTagBody;
+exports.stripCommentTag = stripCommentTag;
+exports.stripBlankChar = stripBlankChar;
+exports.attributeWrapSign = '"';
+exports.cssFilter = defaultCSSFilter;
+exports.getDefaultCSSWhiteList = getDefaultCSSWhiteList;

node_modules/xss/lib/index.js

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+/**
+ * xss
+ *
+ * @author Zongmin Lei<leizongmin@gmail.com>
+ */
+
+var DEFAULT = require("./default");
+var parser = require("./parser");
+var FilterXSS = require("./xss");
+
+/**
+ * filter xss function
+ *
+ * @param {String} html
+ * @param {Object} options { whiteList, onTag, onTagAttr, onIgnoreTag, onIgnoreTagAttr, safeAttrValue, escapeHtml }
+ * @return {String}
+ */
+function filterXSS(html, options) {
+  var xss = new FilterXSS(options);
+  return xss.process(html);
+}
+
+exports = module.exports = filterXSS;
+exports.filterXSS = filterXSS;
+exports.FilterXSS = FilterXSS;
+
+(function () {
+  for (var i in DEFAULT) {
+    exports[i] = DEFAULT[i];
+  }
+  for (var j in parser) {
+    exports[j] = parser[j];
+  }
+})();
+
+// using `xss` on the browser, output `filterXSS` to the globals
+if (typeof window !== "undefined") {
+  window.filterXSS = module.exports;
+}
+
+// using `xss` on the WebWorker, output `filterXSS` to the globals
+function isWorkerEnv() {
+  return (
+    typeof self !== "undefined" &&
+    typeof DedicatedWorkerGlobalScope !== "undefined" &&
+    self instanceof DedicatedWorkerGlobalScope
+  );
+}
+if (isWorkerEnv()) {
+  self.filterXSS = module.exports;
+}

node_modules/xss/lib/parser.js

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+/**
+ * Simple HTML Parser
+ *
+ * @author Zongmin Lei<leizongmin@gmail.com>
+ */
+
+var _ = require("./util");
+
+/**
+ * get tag name
+ *
+ * @param {String} html e.g. '<a hef="#">'
+ * @return {String}
+ */
+function getTagName(html) {
+  var i = _.spaceIndex(html);
+  var tagName;
+  if (i === -1) {
+    tagName = html.slice(1, -1);
+  } else {
+    tagName = html.slice(1, i + 1);
+  }
+  tagName = _.trim(tagName).toLowerCase();
+  if (tagName.slice(0, 1) === "/") tagName = tagName.slice(1);
+  if (tagName.slice(-1) === "/") tagName = tagName.slice(0, -1);
+  return tagName;
+}
+
+/**
+ * is close tag?
+ *
+ * @param {String} html 如：'<a hef="#">'
+ * @return {Boolean}
+ */
+function isClosing(html) {
+  return html.slice(0, 2) === "</";
+}
+
+/**
+ * parse input html and returns processed html
+ *
+ * @param {String} html
+ * @param {Function} onTag e.g. function (sourcePosition, position, tag, html, isClosing)
+ * @param {Function} escapeHtml
+ * @return {String}
+ */
+function parseTag(html, onTag, escapeHtml) {
+  "use strict";
+
+  var rethtml = "";
+  var lastPos = 0;
+  var tagStart = false;
+  var quoteStart = false;
+  var currentPos = 0;
+  var len = html.length;
+  var currentTagName = "";
+  var currentHtml = "";
+
+  chariterator: for (currentPos = 0; currentPos < len; currentPos++) {
+    var c = html.charAt(currentPos);
+    if (tagStart === false) {
+      if (c === "<") {
+        tagStart = currentPos;
+        continue;
+      }
+    } else {
+      if (quoteStart === false) {
+        if (c === "<") {
+          rethtml += escapeHtml(html.slice(lastPos, currentPos));
+          tagStart = currentPos;
+          lastPos = currentPos;
+          continue;
+        }
+        if (c === ">" || currentPos === len - 1) {
+          rethtml += escapeHtml(html.slice(lastPos, tagStart));
+          currentHtml = html.slice(tagStart, currentPos + 1);
+          currentTagName = getTagName(currentHtml);
+          rethtml += onTag(
+            tagStart,
+            rethtml.length,
+            currentTagName,
+            currentHtml,
+            isClosing(currentHtml)
+          );
+          lastPos = currentPos + 1;
+          tagStart = false;
+          continue;
+        }
+        if (c === '"' || c === "'") {
+          var i = 1;
+          var ic = html.charAt(currentPos - i);
+
+          while (ic.trim() === "" || ic === "=") {
+            if (ic === "=") {
+              quoteStart = c;
+              continue chariterator;
+            }
+            ic = html.charAt(currentPos - ++i);
+          }
+        }
+      } else {
+        if (c === quoteStart) {
+          quoteStart = false;
+          continue;
+        }
+      }
+    }
+  }
+  if (lastPos < len) {
+    rethtml += escapeHtml(html.substr(lastPos));
+  }
+
+  return rethtml;
+}
+
+var REGEXP_ILLEGAL_ATTR_NAME = /[^a-zA-Z0-9\\_:.-]/gim;
+
+/**
+ * parse input attributes and returns processed attributes
+ *
+ * @param {String} html e.g. `href="#" target="_blank"`
+ * @param {Function} onAttr e.g. `function (name, value)`
+ * @return {String}
+ */
+function parseAttr(html, onAttr) {
+  "use strict";
+
+  var lastPos = 0;
+  var lastMarkPos = 0;
+  var retAttrs = [];
+  var tmpName = false;
+  var len = html.length;
+
+  function addAttr(name, value) {
+    name = _.trim(name);
+    name = name.replace(REGEXP_ILLEGAL_ATTR_NAME, "").toLowerCase();
+    if (name.length < 1) return;
+    var ret = onAttr(name, value || "");
+    if (ret) retAttrs.push(ret);
+  }
+
+  // 逐个分析字符
+  for (var i = 0; i < len; i++) {
+    var c = html.charAt(i);
+    var v, j;
+    if (tmpName === false && c === "=") {
+      tmpName = html.slice(lastPos, i);
+      lastPos = i + 1;
+      lastMarkPos = html.charAt(lastPos) === '"' || html.charAt(lastPos) === "'" ? lastPos : findNextQuotationMark(html, i + 1);
+      continue;
+    }
+    if (tmpName !== false) {
+      if (
+        i === lastMarkPos
+      ) {
+        j = html.indexOf(c, i + 1);
+        if (j === -1) {
+          break;
+        } else {
+          v = _.trim(html.slice(lastMarkPos + 1, j));
+          addAttr(tmpName, v);
+          tmpName = false;
+          i = j;
+          lastPos = i + 1;
+          continue;
+        }
+      }
+    }
+    if (/\s|\n|\t/.test(c)) {
+      html = html.replace(/\s|\n|\t/g, " ");
+      if (tmpName === false) {
+        j = findNextEqual(html, i);
+        if (j === -1) {
+          v = _.trim(html.slice(lastPos, i));
+          addAttr(v);
+          tmpName = false;
+          lastPos = i + 1;
+          continue;
+        } else {
+          i = j - 1;
+          continue;
+        }
+      } else {
+        j = findBeforeEqual(html, i - 1);
+        if (j === -1) {
+          v = _.trim(html.slice(lastPos, i));
+          v = stripQuoteWrap(v);
+          addAttr(tmpName, v);
+          tmpName = false;
+          lastPos = i + 1;
+          continue;
+        } else {
+          continue;
+        }
+      }
+    }
+  }
+
+  if (lastPos < html.length) {
+    if (tmpName === false) {
+      addAttr(html.slice(lastPos));
+    } else {
+      addAttr(tmpName, stripQuoteWrap(_.trim(html.slice(lastPos))));
+    }
+  }
+
+  return _.trim(retAttrs.join(" "));
+}
+
+function findNextEqual(str, i) {
+  for (; i < str.length; i++) {
+    var c = str[i];
+    if (c === " ") continue;
+    if (c === "=") return i;
+    return -1;
+  }
+}
+
+function findNextQuotationMark(str, i) {
+  for (; i < str.length; i++) {
+    var c = str[i];
+    if (c === " ") continue;
+    if (c === "'" || c === '"') return i;
+    return -1;
+  }
+}
+
+function findBeforeEqual(str, i) {
+  for (; i > 0; i--) {
+    var c = str[i];
+    if (c === " ") continue;
+    if (c === "=") return i;
+    return -1;
+  }
+}
+
+function isQuoteWrapString(text) {
+  if (
+    (text[0] === '"' && text[text.length - 1] === '"') ||
+    (text[0] === "'" && text[text.length - 1] === "'")
+  ) {
+    return true;
+  } else {
+    return false;
+  }
+}
+
+function stripQuoteWrap(text) {
+  if (isQuoteWrapString(text)) {
+    return text.substr(1, text.length - 2);
+  } else {
+    return text;
+  }
+}
+
+exports.parseTag = parseTag;
+exports.parseAttr = parseAttr;

node_modules/xss/lib/util.js

@@ -0,0 +1,34 @@
+module.exports = {
+  indexOf: function (arr, item) {
+    var i, j;
+    if (Array.prototype.indexOf) {
+      return arr.indexOf(item);
+    }
+    for (i = 0, j = arr.length; i < j; i++) {
+      if (arr[i] === item) {
+        return i;
+      }
+    }
+    return -1;
+  },
+  forEach: function (arr, fn, scope) {
+    var i, j;
+    if (Array.prototype.forEach) {
+      return arr.forEach(fn, scope);
+    }
+    for (i = 0, j = arr.length; i < j; i++) {
+      fn.call(scope, arr[i], i, arr);
+    }
+  },
+  trim: function (str) {
+    if (String.prototype.trim) {
+      return str.trim();
+    }
+    return str.replace(/(^\s*)|(\s*$)/g, "");
+  },
+  spaceIndex: function (str) {
+    var reg = /\s|\n|\t/;
+    var match = reg.exec(str);
+    return match ? match.index : -1;
+  },
+};

node_modules/xss/lib/xss.js

@@ -0,0 +1,232 @@
+/**
+ * filter xss
+ *
+ * @author Zongmin Lei<leizongmin@gmail.com>
+ */
+
+var FilterCSS = require("cssfilter").FilterCSS;
+var DEFAULT = require("./default");
+var parser = require("./parser");
+var parseTag = parser.parseTag;
+var parseAttr = parser.parseAttr;
+var _ = require("./util");
+
+/**
+ * returns `true` if the input value is `undefined` or `null`
+ *
+ * @param {Object} obj
+ * @return {Boolean}
+ */
+function isNull(obj) {
+  return obj === undefined || obj === null;
+}
+
+/**
+ * get attributes for a tag
+ *
+ * @param {String} html
+ * @return {Object}
+ *   - {String} html
+ *   - {Boolean} closing
+ */
+function getAttrs(html) {
+  var i = _.spaceIndex(html);
+  if (i === -1) {
+    return {
+      html: "",
+      closing: html[html.length - 2] === "/",
+    };
+  }
+  html = _.trim(html.slice(i + 1, -1));
+  var isClosing = html[html.length - 1] === "/";
+  if (isClosing) html = _.trim(html.slice(0, -1));
+  return {
+    html: html,
+    closing: isClosing,
+  };
+}
+
+/**
+ * shallow copy
+ *
+ * @param {Object} obj
+ * @return {Object}
+ */
+function shallowCopyObject(obj) {
+  var ret = {};
+  for (var i in obj) {
+    ret[i] = obj[i];
+  }
+  return ret;
+}
+
+function keysToLowerCase(obj) {
+  var ret = {};
+  for (var i in obj) {
+    if (Array.isArray(obj[i])) {
+      ret[i.toLowerCase()] = obj[i].map(function (item) {
+        return item.toLowerCase();
+      });
+    } else {
+      ret[i.toLowerCase()] = obj[i];
+    }
+  }
+  return ret;
+}
+
+/**
+ * FilterXSS class
+ *
+ * @param {Object} options
+ *        whiteList (or allowList), onTag, onTagAttr, onIgnoreTag,
+ *        onIgnoreTagAttr, safeAttrValue, escapeHtml
+ *        stripIgnoreTagBody, allowCommentTag, stripBlankChar
+ *        css{whiteList, onAttr, onIgnoreAttr} `css=false` means don't use `cssfilter`
+ */
+function FilterXSS(options) {
+  options = shallowCopyObject(options || {});
+
+  if (options.stripIgnoreTag) {
+    if (options.onIgnoreTag) {
+      console.error(
+        'Notes: cannot use these two options "stripIgnoreTag" and "onIgnoreTag" at the same time'
+      );
+    }
+    options.onIgnoreTag = DEFAULT.onIgnoreTagStripAll;
+  }
+  if (options.whiteList || options.allowList) {
+    options.whiteList = keysToLowerCase(options.whiteList || options.allowList);
+  } else {
+    options.whiteList = DEFAULT.whiteList;
+  }
+
+  this.attributeWrapSign = options.singleQuotedAttributeValue === true ? "'" : DEFAULT.attributeWrapSign;
+
+  options.onTag = options.onTag || DEFAULT.onTag;
+  options.onTagAttr = options.onTagAttr || DEFAULT.onTagAttr;
+  options.onIgnoreTag = options.onIgnoreTag || DEFAULT.onIgnoreTag;
+  options.onIgnoreTagAttr = options.onIgnoreTagAttr || DEFAULT.onIgnoreTagAttr;
+  options.safeAttrValue = options.safeAttrValue || DEFAULT.safeAttrValue;
+  options.escapeHtml = options.escapeHtml || DEFAULT.escapeHtml;
+  this.options = options;
+
+  if (options.css === false) {
+    this.cssFilter = false;
+  } else {
+    options.css = options.css || {};
+    this.cssFilter = new FilterCSS(options.css);
+  }
+}
+
+/**
+ * start process and returns result
+ *
+ * @param {String} html
+ * @return {String}
+ */
+FilterXSS.prototype.process = function (html) {
+  // compatible with the input
+  html = html || "";
+  html = html.toString();
+  if (!html) return "";
+
+  var me = this;
+  var options = me.options;
+  var whiteList = options.whiteList;
+  var onTag = options.onTag;
+  var onIgnoreTag = options.onIgnoreTag;
+  var onTagAttr = options.onTagAttr;
+  var onIgnoreTagAttr = options.onIgnoreTagAttr;
+  var safeAttrValue = options.safeAttrValue;
+  var escapeHtml = options.escapeHtml;
+  var attributeWrapSign = me.attributeWrapSign;
+  var cssFilter = me.cssFilter;
+
+  // remove invisible characters
+  if (options.stripBlankChar) {
+    html = DEFAULT.stripBlankChar(html);
+  }
+
+  // remove html comments
+  if (!options.allowCommentTag) {
+    html = DEFAULT.stripCommentTag(html);
+  }
+
+  // if enable stripIgnoreTagBody
+  var stripIgnoreTagBody = false;
+  if (options.stripIgnoreTagBody) {
+    stripIgnoreTagBody = DEFAULT.StripTagBody(
+      options.stripIgnoreTagBody,
+      onIgnoreTag
+    );
+    onIgnoreTag = stripIgnoreTagBody.onIgnoreTag;
+  }
+
+  var retHtml = parseTag(
+    html,
+    function (sourcePosition, position, tag, html, isClosing) {
+      var info = {
+        sourcePosition: sourcePosition,
+        position: position,
+        isClosing: isClosing,
+        isWhite: Object.prototype.hasOwnProperty.call(whiteList, tag),
+      };
+
+      // call `onTag()`
+      var ret = onTag(tag, html, info);
+      if (!isNull(ret)) return ret;
+
+      if (info.isWhite) {
+        if (info.isClosing) {
+          return "</" + tag + ">";
+        }
+
+        var attrs = getAttrs(html);
+        var whiteAttrList = whiteList[tag];
+        var attrsHtml = parseAttr(attrs.html, function (name, value) {
+          // call `onTagAttr()`
+          var isWhiteAttr = _.indexOf(whiteAttrList, name) !== -1;
+          var ret = onTagAttr(tag, name, value, isWhiteAttr);
+          if (!isNull(ret)) return ret;
+
+          if (isWhiteAttr) {
+            // call `safeAttrValue()`
+            value = safeAttrValue(tag, name, value, cssFilter);
+            if (value) {
+              return name + '=' + attributeWrapSign + value + attributeWrapSign;
+            } else {
+              return name;
+            }
+          } else {
+            // call `onIgnoreTagAttr()`
+            ret = onIgnoreTagAttr(tag, name, value, isWhiteAttr);
+            if (!isNull(ret)) return ret;
+            return;
+          }
+        });
+
+        // build new tag html
+        html = "<" + tag;
+        if (attrsHtml) html += " " + attrsHtml;
+        if (attrs.closing) html += " /";
+        html += ">";
+        return html;
+      } else {
+        // call `onIgnoreTag()`
+        ret = onIgnoreTag(tag, html, info);
+        if (!isNull(ret)) return ret;
+        return escapeHtml(html);
+      }
+    },
+    escapeHtml
+  );
+
+  // if enable stripIgnoreTagBody
+  if (stripIgnoreTagBody) {
+    retHtml = stripIgnoreTagBody.remove(retHtml);
+  }
+
+  return retHtml;
+};
+
+module.exports = FilterXSS;