/*

  * Copyright 2005-2007 The Kuali Foundation

  * 

  * 

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  * 

  * 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.kuali.rice.ksb.security;

 import java.io.BufferedOutputStream;

 import java.io.ByteArrayOutputStream;

 import java.io.IOException;

 import java.io.OutputStream;

 import java.security.GeneralSecurityException;

 import javax.servlet.ServletOutputStream;

 /**

  * An OutputStream which decorates another OutputStream with a wrapper that digitally

  * signs the data when the OutputStream is closed.  Since this class does not know where

  * the resulting digital signature will reside, a DigitalSigner will be invoked to

  * execute the actual signing of the message (i.e. put it in a header).

  * 

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class SignatureSigningOutputStream extends ServletOutputStream {

         private boolean delayWrite;

         private DigitalSigner signer;

         private BufferedOutputStream bufferedDataHoldingStream;

         private ByteArrayOutputStream dataHoldingStream;

         private OutputStream wrappedOutputStream;

         /**

          * Constructs a SignatureSigningOutputStream with the given DigitalSigner and underlying OutputStream.

          * If true, the delayWrite boolean indicates that the stream should store all data internally until the

          * stream is closed, at which point it should forward all data to the wrapped OutputStream.  If delayWrite

          * is false, then the data will be forwarded immediately.

          */

         public SignatureSigningOutputStream(DigitalSigner signer, OutputStream wrappedOutputStream, boolean delayWrite) {

                 super();

                 this.delayWrite = delayWrite;

                 if (delayWrite) {

                     this.dataHoldingStream = new ByteArrayOutputStream();

                     this.bufferedDataHoldingStream = new BufferedOutputStream(this.dataHoldingStream);

                 }

                 this.wrappedOutputStream = wrappedOutputStream;

                 this.signer = signer;

         }

         public void write(int data) throws IOException {

                 if (this.delayWrite) {

                     this.bufferedDataHoldingStream.write(data);

                 } else {

                     this.wrappedOutputStream.write(data);

                 }

                 try {

                     this.signer.getSignature().update((byte)data);        

                 } catch (GeneralSecurityException e) {

                         IOException exception = new IOException("Error updating signature.");

                         exception.initCause(e);

                         throw exception;

                 }

         }

         @Override

         public void close() throws IOException {

                 // before we close, sign the message

                 try {

                     this.signer.sign();

                         if (this.delayWrite) {

                             this.bufferedDataHoldingStream.close();

                                 byte[] data = this.dataHoldingStream.toByteArray();

                                 for (int index = 0; index < data.length; index++) {

                                     this.wrappedOutputStream.write(data[index]);

                                 }

                         }

                         this.wrappedOutputStream.close();

                 } catch (Exception e) {

                         IOException exception = new IOException("Error attaching digital signature to outbound response.");

                         exception.initCause(e);

                         throw exception;

                 } finally {

                         super.close();

                 }

         }

 }