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A library for performing fast, configurable cleansing of HTML coming from untrusted sources.
/*
* Copyright (c) 2007-2011, Arshan Dabirsiaghi, Jason Li
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of OWASP nor the names of its contributors may be used to
* endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.owasp.validator.css;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.ResourceBundle;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpContentTooLargeException;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpConnectionManagerParams;
import org.owasp.validator.html.InternalPolicy;
import org.owasp.validator.html.Policy;
import org.owasp.validator.html.ScanException;
import org.owasp.validator.html.util.ErrorMessageUtil;
import org.owasp.validator.html.util.HTMLEntityEncoder;
import org.w3c.css.sac.InputSource;
public class ExternalCssScanner extends CssScanner {
public ExternalCssScanner(InternalPolicy policy, ResourceBundle messages) {
super(policy, messages);
}
/**
* Parses through a LinkedList of imported stylesheet
* URIs, this method parses through those stylesheets and validates them
*
* @param stylesheets
* the LinkedList of stylesheet URIs to
* parse
* @param handler
* the CssHandler to use for parsing
* @param errorMessages
* the list of error messages to append to
* @param sizeLimit
* the limit on the total size in bites of any imported
* stylesheets
* @throws ScanException
* if an error occurs during scanning
*/
protected void parseImportedStylesheets(LinkedList stylesheets, CssHandler handler,
ArrayList errorMessages, int sizeLimit) throws ScanException {
int importedStylesheets = 0;
// if stylesheets were imported by the inline style declaration,
// continue parsing the nested styles. Note this only happens
// if CSS importing was enabled in the policy file
if (!stylesheets.isEmpty()) {
HttpClient httpClient = new HttpClient();
// Ensure that we have appropriate timeout values so we don't
// get DoSed waiting for returns
HttpConnectionManagerParams params = httpClient
.getHttpConnectionManager().getParams();
int timeout = DEFAULT_TIMEOUT;
try {
timeout = Integer.parseInt(policy
.getDirective(Policy.CONNECTION_TIMEOUT));
} catch (NumberFormatException nfe) {
}
params.setConnectionTimeout(timeout);
params.setSoTimeout(timeout);
httpClient.getHttpConnectionManager().setParams(params);
int allowedImports = Policy.DEFAULT_MAX_STYLESHEET_IMPORTS;
try {
allowedImports = Integer.parseInt(policy
.getDirective("maxStyleSheetImports"));
} catch (NumberFormatException nfe) {
}
while (!stylesheets.isEmpty()) {
URI stylesheetUri = (URI) stylesheets.removeFirst();
if (++importedStylesheets > allowedImports) {
errorMessages.add(ErrorMessageUtil.getMessage(
messages,
ErrorMessageUtil.ERROR_CSS_IMPORT_EXCEEDED,
new Object[] {
HTMLEntityEncoder
.htmlEntityEncode(stylesheetUri
.toString()),
String.valueOf(allowedImports) }));
continue;
}
GetMethod stylesheetRequest = new GetMethod(stylesheetUri
.toString());
byte[] stylesheet = null;
try {
// pull down stylesheet, observing size limit
httpClient.executeMethod(stylesheetRequest);
stylesheet = stylesheetRequest.getResponseBody(sizeLimit);
} catch (HttpContentTooLargeException hctle) {
errorMessages
.add(ErrorMessageUtil
.getMessage(
messages,
ErrorMessageUtil.ERROR_CSS_IMPORT_INPUT_SIZE,
new Object[] {
HTMLEntityEncoder
.htmlEntityEncode(stylesheetUri
.toString()),
String.valueOf(policy
.getMaxInputSize()) }));
} catch (IOException ioe) {
errorMessages.add(ErrorMessageUtil
.getMessage(
messages,
ErrorMessageUtil.ERROR_CSS_IMPORT_FAILURE,
new Object[] { HTMLEntityEncoder
.htmlEntityEncode(stylesheetUri
.toString()) }));
} finally {
stylesheetRequest.releaseConnection();
}
if (stylesheet != null) {
// decrease the size limit based on the
sizeLimit -= stylesheet.length;
try {
InputSource nextStyleSheet = new InputSource(
new InputStreamReader(new ByteArrayInputStream(
stylesheet)));
parser.parseStyleSheet(nextStyleSheet);
} catch (IOException ioe) {
throw new ScanException(ioe);
}
}
}
}
}
}