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diff --git a/netx/net/sourceforge/jnlp/util/JarFile.java b/netx/net/sourceforge/jnlp/util/JarFile.java
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+/*
+ Copyright (C) 2012 Red Hat, Inc.
+
+ This file is part of IcedTea.
+
+ IcedTea is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ IcedTea is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with IcedTea; see the file COPYING.  If not, write to the
+ Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ 02110-1301 USA.
+
+ Linking this library statically or dynamically with other modules is
+ making a combined work based on this library.  Thus, the terms and
+ conditions of the GNU General Public License cover the whole
+ combination.
+
+ As a special exception, the copyright holders of this library give you
+ permission to link this library with independent modules to produce an
+ executable, regardless of the license terms of these independent
+ modules, and to copy and distribute the resulting executable under
+ terms of your choice, provided that you also meet, for each linked
+ independent module, the terms and conditions of the license of that
+ module.  An independent module is a module which is not derived from
+ or based on this library.  If you modify this library, you may extend
+ this exception to your version of the library, but you are not
+ obligated to do so.  If you do not wish to do so, delete this
+ exception statement from your version. */
+package net.sourceforge.jnlp.util;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.ZipFile;
+import net.sourceforge.jnlp.runtime.JNLPRuntime;
+
+public class JarFile extends java.util.jar.JarFile {
+
+    public JarFile(String name) throws IOException {
+       super(name);
+       verifyZipHeader(new File(name));
+    }
+
+    /**
+     */
+    public JarFile(String name, boolean verify) throws IOException {
+        super(name, verify);
+        verifyZipHeader(new File(name));
+    }
+
+    /**
+     */
+    public JarFile(File file) throws IOException {
+        super(file);
+        verifyZipHeader(file);
+    }
+
+    /**
+     */
+    public JarFile(File file, boolean verify) throws IOException {
+        super(file, verify);
+        verifyZipHeader(file);
+    }
+
+    /*
+     */
+    public JarFile(File file, boolean verify, int mode) throws IOException {
+        super(file, verify, mode);
+         verifyZipHeader(file);
+    }
+    
+    
+    
+    
+    /**
+     * According to specification -
+     * http://www.pkware.com/documents/casestudies/APPNOTE.TXT or just google
+     * around zip header all entries in zip-compressed must start with well
+     * known "PK" which is defined as hexa x50 x4b x03 x04, which in decimal are
+     * 80 75 3 4.
+     * 
+     * Note - this is not file-header, it is item-header.
+     *
+     * Actually most of compressing formats have some n-bytes header se eg:
+     * http://www.gzip.org/zlib/rfc-gzip.html#header-trailer for ID1 and ID2 so
+     * in case that some differently compressed jars will come to play, this is
+     * the palce where to fix it.
+     *
+     */
+    private static final byte[] ZIP_LOCAL_FILE_HEADER_SIGNATURE = new byte[]{80, 75, 3, 4};
+
+    /**
+     * This method is checking first four bytes of jar-file against
+     * ZIP_LOCAL_FILE_HEADER_SIGNATURE
+     *
+     * Although zip specification allows to skip all corrupted entries, it is
+     * not safe for jars. If first four bytes of file are not zip
+     * ZIP_LOCAL_FILE_HEADER_SIGNATURE then exception is thrown
+     * 
+     * As noted, ZIP_LOCAL_FILE_HEADER_SIGNATURE is not ile-header, but is item-header.
+     * Possible attack is using the fact that entries without header are considered
+     * corrupted and so can be ignoered. However, for other they can have some meaning.
+     * 
+     * So for our purposes we must insists on first record to be valid.
+     *
+     * @param file
+     * @throws IOException, InvalidJarHeaderException
+     */
+    public static void verifyZipHeader(File file) throws IOException {
+        if (!JNLPRuntime.isIgnoreHeaders()) {
+            InputStream s = new FileInputStream(file);
+            try {
+                byte[] buffer = new byte[ZIP_LOCAL_FILE_HEADER_SIGNATURE.length];
+                /*
+                 * for case that new byte[] will accidently initialize same
+                 * sequence as zip header and during the read the buffer will not be filled
+                 */                
+                for (int i = 0; i < buffer.length; i++) {
+                    buffer[i] = 0;
+                }
+                int toRead = ZIP_LOCAL_FILE_HEADER_SIGNATURE.length;
+                int readSoFar = 0;
+                int n = 0;
+                /*
+                 * this is used instead of s.read(buffer) for case of block and
+                 * so returned not-fully-filled dbuffer
+                 */ 
+                while ((n = s.read(buffer, readSoFar, buffer.length - readSoFar)) != -1) {
+                    readSoFar += n;
+                    if (readSoFar == toRead) {
+                        break;
+                    }
+                }
+                for (int i = 0; i < buffer.length; i++) {
+                    if (buffer[i] != ZIP_LOCAL_FILE_HEADER_SIGNATURE[i]) {
+                        throw new InvalidJarHeaderException("Jar " + file.getName() + " do not heave valid header. You can skip this check by -Xignoreheaders");
+                    }
+                }
+            } finally {
+                s.close();
+            }
+        }
+    }
+}