[GitHub] keith-turner commented on a change in pull request #300: ACCUMULO-4708 Limit RFile block size to 2GB

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keith-turner commented on a change in pull request #300: ACCUMULO-4708 Limit RFile block size to 2GB
URL: https://github.com/apache/accumulo/pull/300#discussion_r147172071
 
 

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 File path: core/src/main/java/org/apache/accumulo/core/security/crypto/RFileCipherOutputStream.java
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 @@ -0,0 +1,95 @@
+/*
+ * 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.
+ */
+package org.apache.accumulo.core.security.crypto;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+import javax.crypto.Cipher;
+import javax.crypto.CipherOutputStream;
+
+/**
+ *
+ * This class extends {@link CipherOutputStream} to include a way to track the number of bytes that have
+ * been encrypted by the stream. The write method also includes a mechanism to stop writing and
+ * throw an exception if exceeding a maximum number of bytes is attempted.
+ *
+ */
+public class RFileCipherOutputStream extends CipherOutputStream {
+
+  // This is the maximum size encrypted stream that can be written. Attempting to write anything larger
+  // will cause an exception. Given that each block in an rfile is encrypted separately, and blocks
+  // should be written such that a block cannot ever reach 16GiB, this is believed to be a safe number.
+  // If this does cause an exception, it is an issue best addressed elsewhere.
+  private final long maxOutputSize = 1L << 34; //16GiB
+
+  // the cipher engine to use to process stream data
+  private Cipher cipher;
+
+  // the underlying output stream
+  private OutputStream output;
+
+  // the buffer holding data ready to be written out
+  private byte[] obuffer;
+
+  // The total number of bytes that have been written out
+  private long count = 0;
+
+  /**
+   *
+   * Constructs a RFileCipherOutputStream
+   *
+   * @param os
+   *          the OutputStream object
+   * @param c
+   *          an initialized Cipher object
+   */
+  public RFileCipherOutputStream(OutputStream os, Cipher c) {
+    super(os, c);
+    output = os;
+    cipher = c;
+  }
+
+  /**
+   * Override of CipherOutputStream's write to count the number of bytes that have been encrypted.
+   * This method now throws an exception if an attempt to write bytes beyond a maximum is made.
+   *
+   * Writes <code>len</code> bytes from the specified byte array starting at offset <code>off</code> to this output stream.
+   *
+   * @param b
+   *          the data.
+   * @param off
+   *          the start offset in the data.
+   * @param len
+   *          the number of bytes to write.
+   * @exception IOException
+   *              if an I/O error occurs.
+   * @since JCE1.2
+   */
+  @Override
+  public void write(byte b[], int off, int len) throws IOException {
+    count += len;
+    if (count > maxOutputSize) {
+      throw new IOException("Attempt to write " + count + " bytes was made. A maximum of " + maxOutputSize + " is allowed for an encryption stream.");
+    }
+    obuffer = cipher.update(b, off, len);
 
 Review comment:
   can you call super.write here?

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