org.etudes.component.app.jforum.util.html.SafeHtml.java Source code

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Here is the source code for org.etudes.component.app.jforum.util.html.SafeHtml.java

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/**********************************************************************************
 * $URL: https://source.sakaiproject.org/contrib/etudes/sakai-jforum/tags/2.9.11/jforum-impl/impl/src/java/org/etudes/component/app/jforum/util/html/SafeHtml.java $ 
 * $Id: SafeHtml.java 83559 2013-04-30 19:03:29Z murthy@etudes.org $ 
 *********************************************************************************** 
 * 
 * Copyright (c) 2008, 2009, 2010, 2011, 2012 Etudes, Inc. 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * 
 * http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 ***********************************************************************************/
package org.etudes.component.app.jforum.util.html;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class SafeHtml {
    private static final Log logger = LogFactory.getLog(SafeHtml.class);
    //private Set welcomeTags;

    private SafeHtml() {
    }

    /**
     * Replace the characters < and > with &lt; and &gt; associated with text "script"
     * 
     * @param contents
     *        string that is to be modified
     * @return modifeed string
     */
    public static String escapeJavascript(String contents) {
        if (contents == null)
            return null;

        String result = null;
        result = contents.replaceAll("<([\\/]*[sS][cC][rR][iI][pP][tT])>*?>", "&lt;$1&gt;");
        result = result.replaceAll("<([sS][cC][rR][iI][pP][tT])[\\s+][^\\<]*>*?>", "&lt;$1&gt;");

        return result;
    }

    /**
     * Replace the characters < and > with space associated with text "script"
     * 
     * @param contents
     *        string that is to be modified
     * @return modifeed string
     */
    public static String escapeScriptTagWithSpace(String contents) {
        if (contents == null)
            return null;

        String result = null;
        result = contents.replaceAll("<\\/*([sS][cC][rR][iI][pP][tT])>*?>", " $1 ");
        result = result.replaceAll("<([sS][cC][rR][iI][pP][tT])[\\s+][^\\<]*>*?>", " $1 ");

        return result;
    }

    /**
     * regular expression that tests for the existence of malicious characters and replaces them with a space.
     */
    public static String escapeWithSpace(String contents) {
        if (contents == null)
            return null;

        String filterPattern = "[<>{}\\[\\];\\&]";
        String result = contents.replaceAll(filterPattern, " ");

        return result;
    }

    /**
     * remove excess spaces from the string
     * 
     * @param contents
     *        post content
     * @return modified content
     */
    public static String removeExcessSpaces(String contents) {
        if (contents == null)
            return null;

        String filterPattern = "(&amp;nbsp;|&nbsp;){10,}+";
        String result = contents.replaceAll(filterPattern, " ");

        return result;
    }

    /**
     * removes existing target attribute in the anchor tag and adds target="_blank"
     * 
     * @param contents
     *        Post contest
     * 
     * @return Modified content with target="_blank" in anchor tags
     */
    public static String addAnchorTarget(String contents) {
        if (contents == null) {
            return null;
        }

        StringBuffer sb = new StringBuffer();

        Pattern p = Pattern.compile("<(a)([^>]+)>", Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
        Matcher m = p.matcher(contents);

        while (m.find()) {
            if (m.groupCount() == 2) {
                String group1 = m.group(1);
                String group2 = m.group(2);
                String modGroup2 = group2.replaceAll("(target\\s*=\\s*[\"\'][^\"\']*[\"\']\\s*)?", "");

                String modString = "<" + group1 + " target=\"_blank\" " + modGroup2 + ">";

                m.appendReplacement(sb, Matcher.quoteReplacement(modString));
            }
        }

        m.appendTail(sb);

        return sb.toString();
    }
}