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*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
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****************************************************************************/
package org.apache.pdfbox.preflight.process;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_SYNTAX_STREAM_DAMAGED;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_SYNTAX_STREAM_FX_KEYS;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_SYNTAX_STREAM_INVALID_FILTER;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_SYNTAX_STREAM_LENGTH_INVALID;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_SYNTAX_STREAM_LENGTH_MISSING;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import org.apache.commons.io.IOUtils;
import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSBase;
import org.apache.pdfbox.cos.COSDocument;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.cos.COSObject;
import org.apache.pdfbox.cos.COSStream;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.persistence.util.COSObjectKey;
import org.apache.pdfbox.preflight.PreflightContext;
import org.apache.pdfbox.preflight.ValidationResult.ValidationError;
import org.apache.pdfbox.preflight.exception.ValidationException;
import org.apache.pdfbox.preflight.utils.COSUtils;
import org.apache.pdfbox.preflight.utils.FilterHelper;
public class StreamValidationProcess extends AbstractProcess
{
public void validate(PreflightContext ctx) throws ValidationException
{
PDDocument pdfDoc = ctx.getDocument();
COSDocument cDoc = pdfDoc.getDocument();
List<?> lCOSObj = cDoc.getObjects();
for (Object o : lCOSObj)
{
COSObject cObj = (COSObject) o;
/*
* If this object represents a Stream, the Dictionary must contain the Length key
*/
COSBase cBase = cObj.getObject();
if (cBase instanceof COSStream)
{
validateStreamObject(ctx, cObj);
}
}
}
public void validateStreamObject(PreflightContext context, COSObject cObj) throws ValidationException
{
COSStream streamObj = (COSStream) cObj.getObject();
// ---- Check dictionary entries
// ---- Only the Length entry is mandatory
// ---- In a PDF/A file, F, FFilter and FDecodeParms are forbidden
checkDictionaryEntries(context, streamObj);
// ---- check stream length
checkStreamLength(context, cObj);
// ---- Check the Filter value(s)
checkFilters(streamObj, context);
}
/**
* This method checks if one of declared Filter is LZWdecode. If LZW is found, the result list is updated with an
* error code.
*
* @param stream the stream to check.
* @param context the preflight context.
*/
protected void checkFilters(COSStream stream, PreflightContext context)
{
COSBase bFilter = stream.getItem(COSName.FILTER);
if (bFilter != null)
{
COSDocument cosDocument = context.getDocument().getDocument();
if (COSUtils.isArray(bFilter, cosDocument))
{
COSArray afName = (COSArray) bFilter;
for (int i = 0; i < afName.size(); ++i)
{
FilterHelper.isAuthorizedFilter(context, afName.getString(i));
}
}
else if (bFilter instanceof COSName)
{
String fName = ((COSName) bFilter).getName();
FilterHelper.isAuthorizedFilter(context, fName);
}
else
{
// ---- The filter type is invalid
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_INVALID_FILTER,
"Filter should be a Name or an Array"));
}
}
// else Filter entry is optional
}
private boolean readUntilStream(InputStream ra) throws IOException
{
boolean search = true;
// String stream = "";
boolean maybe = false;
int lastChar = -1;
do
{
int c = ra.read();
switch (c)
{
case 's':
// stream = "s";
maybe = true;
lastChar = c;
break;
case 't':
// if (maybe && stream.endsWith("s")) {
if (maybe && lastChar == 's')
{
// stream = stream + "t";
lastChar = c;
}
else
{
maybe = false;
lastChar = -1;
}
break;
case 'r':
// if (maybe && stream.endsWith("t")) {
if (maybe && lastChar == 't')
{
// stream = stream + "r";
lastChar = c;
}
else
{
maybe = false;
lastChar = -1;
}
break;
case 'e':
// if (maybe && stream.endsWith("r")) {
if (maybe && lastChar == 'r')
{
lastChar = c;
// stream = stream + "e";
}
else
{
maybe = false;
}
break;
case 'a':
// if (maybe && stream.endsWith("e")) {
if (maybe && lastChar == 'e')
{
lastChar = c;
// stream = stream + "a";
}
else
{
maybe = false;
}
break;
case 'm':
// if (maybe && stream.endsWith("a")) {
if (maybe && lastChar == 'a')
{
return true;
}
else
{
maybe = false;
}
break;
case -1:
search = false;
break;
default:
maybe = false;
break;
}
} while (search);
return false;
}
protected void checkStreamLength(PreflightContext context, COSObject cObj) throws ValidationException
{
COSStream streamObj = (COSStream) cObj.getObject();
int length = streamObj.getInt(COSName.LENGTH);
InputStream ra = null;
try
{
ra = context.getSource().getInputStream();
Long offset = context.getDocument().getDocument().getXrefTable().get(new COSObjectKey(cObj));
// ---- go to the beginning of the object
long skipped = 0;
if (offset != null)
{
while (skipped != offset)
{
long curSkip = ra.skip(offset - skipped);
if (curSkip < 0)
{
org.apache.pdfbox.io.IOUtils.closeQuietly(ra);
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_DAMAGED, "Unable to skip bytes in the PDFFile to check stream length"));
return;
}
skipped += curSkip;
}
// ---- go to the stream key word
if (readUntilStream(ra))
{
int c = ra.read();
if (c == '\r')
{
ra.read();
} // else c is '\n' no more character to read
// ---- Here is the true beginning of the Stream Content.
// ---- Read the given length of bytes and check the 10 next bytes
// ---- to see if there are endstream.
byte[] buffer = new byte[1024];
int nbBytesToRead = length;
do
{
int cr = 0;
if (nbBytesToRead > 1024)
{
cr = ra.read(buffer, 0, 1024);
}
else
{
cr = ra.read(buffer, 0, nbBytesToRead);
}
if (cr == -1)
{
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_LENGTH_INVALID,
"Stream length is invalid [cObj="+cObj.toString()+"]"));
org.apache.pdfbox.io.IOUtils.closeQuietly(ra);
return;
}
else
{
nbBytesToRead = nbBytesToRead - cr;
}
} while (nbBytesToRead > 0);
int len = "endstream".length() + 2;
byte[] buffer2 = new byte[len];
for (int i = 0; i < len; ++i)
{
buffer2[i] = (byte) ra.read();
}
// ---- check the content of 10 last characters
String endStream = new String(buffer2);
if (buffer2[0] == '\r' && buffer2[1] == '\n')
{
if (!endStream.contains("endstream"))
{
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_LENGTH_INVALID,
"Stream length is invalid [cObj="+cObj.toString()+"; defined length="+length+"; buffer2="+endStream+"]"));
}
}
else if (buffer2[0] == '\r' && buffer2[1] == 'e')
{
if (!endStream.contains("endstream"))
{
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_LENGTH_INVALID,
"Stream length is invalid [cObj="+cObj.toString()+"; defined length="+length+"; buffer2="+endStream+"]"));
}
}
else if (buffer2[0] == '\n' && buffer2[1] == 'e')
{
if (!endStream.contains("endstream"))
{
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_LENGTH_INVALID,
"Stream length is invalid [cObj="+cObj.toString()+"; defined length="+length+"; buffer2="+endStream+"]"));
}
}
else
{
if (!endStream.startsWith("endStream")) {
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_LENGTH_INVALID,
"Stream length is invalid [cObj="+cObj.toString()+"; defined length="+length+"; buffer2="+endStream+"]"));
}
}
}
else
{
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_LENGTH_INVALID,
"Stream length is invalid"));
}
}
}
catch (IOException e)
{
throw new ValidationException("Unable to read a stream to validate it due to : " + e.getMessage(), e);
}
finally
{
if (ra != null)
{
IOUtils.closeQuietly(ra);
}
}
}
/**
* Check dictionary entries. Only the Length entry is mandatory. In a PDF/A file, F, FFilter and FDecodeParms are
* forbidden
*
* @param context the preflight context.
* @param streamObj the stream to check.
*/
protected void checkDictionaryEntries(PreflightContext context, COSStream streamObj)
{
boolean len = streamObj.containsKey(COSName.LENGTH);
boolean f = streamObj.containsKey(COSName.F);
boolean ffilter = streamObj.containsKey(COSName.F_FILTER);
boolean fdecParams = streamObj.containsKey(COSName.F_DECODE_PARMS);
if (!len)
{
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_LENGTH_MISSING,
"Stream length is missing"));
}
if (f || ffilter || fdecParams)
{
addValidationError(context, new ValidationError(ERROR_SYNTAX_STREAM_FX_KEYS,
"F, FFilter or FDecodeParms keys are present in the stream dictionary"));
}
}
}