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/**
* 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;
}
/**
* FilterXSS class
*
* @param {Object} options
* whiteList, 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;
}
options.whiteList = options.whiteList || DEFAULT.whiteList;
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 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) {
var 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: whiteList.hasOwnProperty(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 + '="' + value + '"';
} else {
return name;
}
} else {
// call `onIgnoreTagAttr()`
var ret = onIgnoreTagAttr(tag, name, value, isWhiteAttr);
if (!isNull(ret)) return ret;
return;
}
});
// build new tag html
var html = "<" + tag;
if (attrsHtml) html += " " + attrsHtml;
if (attrs.closing) html += " /";
html += ">";
return html;
} else {
// call `onIgnoreTag()`
var 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;
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