org.apache.tika.sax
Class SecureContentHandler

java.lang.Object
  org.xml.sax.helpers.DefaultHandler
      org.apache.tika.sax.ContentHandlerDecorator
          org.apache.tika.sax.SecureContentHandler

All Implemented Interfaces:

org.xml.sax.ContentHandler, org.xml.sax.DTDHandler, org.xml.sax.EntityResolver, org.xml.sax.ErrorHandler

public class SecureContentHandler
extends ContentHandlerDecorator

Content handler decorator that attempts to prevent denial of service attacks against Tika parsers.

Currently this class simply compares the number of output characters to to the number of input bytes, and throws an exception if the output is truly excessive when compared to the input. This is a strong indication of a zip bomb.

Since:

Apache Tika 0.4

See Also:

TIKA-216

Constructor Summary

SecureContentHandler(org.xml.sax.ContentHandler handler, CountingInputStream stream)
Decorates the given content handler with zip bomb prevention based on the count of bytes read from the given counting input stream.

Method Summary

void	characters(char[] ch, int start, int length)
long	getMaximumCompressionRatio() Returns the maximum compression ratio.
long	getOutputThreshold() Returns the configured output threshold.
void	ignorableWhitespace(char[] ch, int start, int length)
void	setMaximumCompressionRatio(long ratio) Sets the ratio between output characters and input bytes.
void	setOutputThreshold(long threshold) Sets the threshold for output characters before the zip bomb prevention is activated.
void	throwIfCauseOf(org.xml.sax.SAXException e) Converts the given SAXException to a corresponding TikaException if it's caused by this instance detecting a zip bomb.

Methods inherited from class org.apache.tika.sax.ContentHandlerDecorator

endDocument, endElement, endPrefixMapping, handleException, processingInstruction, setContentHandler, setDocumentLocator, skippedEntity, startDocument, startElement, startPrefixMapping, toString

Methods inherited from class org.xml.sax.helpers.DefaultHandler

error, fatalError, notationDecl, resolveEntity, unparsedEntityDecl, warning

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

SecureContentHandler

public SecureContentHandler(org.xml.sax.ContentHandler handler,
                            CountingInputStream stream)

Decorates the given content handler with zip bomb prevention based on the count of bytes read from the given counting input stream. The resulting decorator can be passed to a Tika parser along with the given counting input stream.

Parameters:

handler - the content handler to be decorated

stream - the input stream to be parsed, wrapped into a CountingInputStream decorator

Method Detail

getOutputThreshold

public long getOutputThreshold()

Returns the configured output threshold.

Returns:

output threshold

setOutputThreshold

public void setOutputThreshold(long threshold)

Sets the threshold for output characters before the zip bomb prevention is activated. This avoids false positives in cases where an otherwise normal document for some reason starts with a highly compressible sequence of bytes.

Parameters:

threshold - new output threshold

getMaximumCompressionRatio

public long getMaximumCompressionRatio()

Returns the maximum compression ratio.

Returns:

maximum compression ratio

setMaximumCompressionRatio

public void setMaximumCompressionRatio(long ratio)

Sets the ratio between output characters and input bytes. If this ratio is exceeded (after the output threshold has been reached) then an exception gets thrown.

Parameters:

ratio - new maximum compression ratio

throwIfCauseOf

public void throwIfCauseOf(org.xml.sax.SAXException e)
                    throws TikaException

Converts the given SAXException to a corresponding TikaException if it's caused by this instance detecting a zip bomb.

Parameters:

e - SAX exception

Throws:

TikaException - zip bomb exception

characters

public void characters(char[] ch,
                       int start,
                       int length)
                throws org.xml.sax.SAXException

Specified by:

characters in interface org.xml.sax.ContentHandler

Overrides:

characters in class ContentHandlerDecorator

Throws:

org.xml.sax.SAXException

ignorableWhitespace

public void ignorableWhitespace(char[] ch,
                                int start,
                                int length)
                         throws org.xml.sax.SAXException

Specified by:

ignorableWhitespace in interface org.xml.sax.ContentHandler

Overrides:

ignorableWhitespace in class ContentHandlerDecorator

Throws:

org.xml.sax.SAXException