/**

  * Copyright 2005-2011 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.ByteArrayInputStream;

 import java.io.IOException;

 import java.security.Signature;

 import java.security.cert.CertificateFactory;

 import javax.servlet.ServletInputStream;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletRequestWrapper;

 import org.apache.commons.codec.binary.Base64;

 import org.apache.commons.lang.StringUtils;

 import org.kuali.rice.ksb.service.KSBServiceLocator;

 import org.kuali.rice.ksb.util.KSBConstants;

 /**

  * An HttpServletRequestWrapper which will wraps the underlying request's InputStream in a 

  * SignatureVerifyingInputStream which will verify the digital signature of the request after 

  * all of the data has been read from the input stream.

  * 

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

  */

 public class SignatureVerifyingRequestWrapper extends HttpServletRequestWrapper {

         private byte[] digitalSignature;

         private Signature signature;

         public SignatureVerifyingRequestWrapper(HttpServletRequest request) {

                 super(request);

                 String encodedSignature = request.getHeader(KSBConstants.DIGITAL_SIGNATURE_HEADER);

                 if (StringUtils.isEmpty(encodedSignature)) {

                         throw new RuntimeException("A digital signature was required on the request but none was found.");

                 }

                 String verificationAlias = request.getHeader(KSBConstants.KEYSTORE_ALIAS_HEADER);

                 String encodedCertificate = request.getHeader(KSBConstants.KEYSTORE_CERTIFICATE_HEADER);

                 if ( (StringUtils.isEmpty(verificationAlias)) && (StringUtils.isEmpty(encodedCertificate)) ) {

             throw new RuntimeException("A verification alias or certificate was required on the request but neither was found.");

                 }

                 try {

             this.digitalSignature = Base64.decodeBase64(encodedSignature.getBytes("UTF-8"));

             if (StringUtils.isNotBlank(encodedCertificate)) {

                 byte[] certificate = Base64.decodeBase64(encodedCertificate.getBytes("UTF-8"));

                 CertificateFactory cf = CertificateFactory.getInstance("X.509");

                 this.signature = KSBServiceLocator.getDigitalSignatureService().getSignatureForVerification(cf.generateCertificate(new ByteArrayInputStream(certificate)));

             } else if (StringUtils.isNotBlank(verificationAlias)) {

                 this.signature = KSBServiceLocator.getDigitalSignatureService().getSignatureForVerification(verificationAlias);

             }

                 } catch (Exception e) {

                         throw new RuntimeException("Failed to initialize digital signature verification.", e);

                 }

         }

         @Override

         public ServletInputStream getInputStream() throws IOException {

                 return new SignatureVerifyingInputStream(this.digitalSignature, this.signature, super.getInputStream());

         }

 }