/*
 * Copyright 2002-2005 The Apache Software Foundation.
 *
 * Licensed 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.
 */

/*
 * XSEC
 *
 * OpenSSLCryptoHashHMAC := OpenSSL Implementation of HMAC
 *
 * Author(s): Berin Lautenbach
 *
 * $Id$
 *
 */

#include <xsec/framework/XSECDefs.hpp>
#if defined (HAVE_OPENSSL)


#include <xsec/enc/OpenSSL/OpenSSLCryptoHashHMAC.hpp>
#include <xsec/enc/XSECCryptoException.hpp>
#include <xsec/enc/XSECCryptoKeyHMAC.hpp>

#include <memory.h>

// Constructors/Destructors

OpenSSLCryptoHashHMAC::OpenSSLCryptoHashHMAC(HashType alg) {

	// Initialise the digest

	switch (alg) {

	case (XSECCryptoHash::HASH_SHA1) :
	
		mp_md = EVP_get_digestbyname("SHA1");
		break;

	case (XSECCryptoHash::HASH_MD5) :
	
		mp_md = EVP_get_digestbyname("MD5");
		break;

	case (XSECCryptoHash::HASH_SHA224) :
	
		mp_md = EVP_get_digestbyname("SHA224");
		if (mp_md == NULL) {
			throw XSECCryptoException(XSECCryptoException::MDError,
			"OpenSSL:Hash - SHA224 not supported by this version of OpenSSL"); 
		}

		break;

	case (XSECCryptoHash::HASH_SHA256) :
	
		mp_md = EVP_get_digestbyname("SHA256");
		if (mp_md == NULL) {
			throw XSECCryptoException(XSECCryptoException::MDError,
			"OpenSSL:Hash - SHA256 not supported by this version of OpenSSL"); 
		}

		break;

	case (XSECCryptoHash::HASH_SHA384) :
	
		mp_md = EVP_get_digestbyname("SHA384");
		if (mp_md == NULL) {
			throw XSECCryptoException(XSECCryptoException::MDError,
			"OpenSSL:Hash - SHA384 not supported by this version of OpenSSL"); 
		}

		break;

	case (XSECCryptoHash::HASH_SHA512) :
	
		mp_md = EVP_get_digestbyname("SHA512");
		if (mp_md == NULL) {
			throw XSECCryptoException(XSECCryptoException::MDError,
			"OpenSSL:Hash - SHA512 not supported by this version of OpenSSL"); 
		}

		break;

	default :

		mp_md = NULL;

	}

	if(!mp_md) {

		throw XSECCryptoException(XSECCryptoException::MDError,
			"OpenSSL:HashHMAC - Error loading Message Digest"); 
	}

	m_initialised = false;
	m_hashType = alg;

}

void OpenSSLCryptoHashHMAC::setKey(XSECCryptoKey *key) {

	// Use this to initialise the HMAC Context

	if (key->getKeyType() != XSECCryptoKey::KEY_HMAC) {

		throw XSECCryptoException(XSECCryptoException::MDError,
			"OpenSSL:HashHMAC - Non HMAC Key passed to OpenSSLHashHMAC");

	}

	m_keyLen = ((XSECCryptoKeyHMAC *) key)->getKey(m_keyBuf);


	HMAC_Init(&m_hctx, 
		m_keyBuf.rawBuffer(),
		m_keyLen,
		mp_md);

	m_initialised = true;

}

OpenSSLCryptoHashHMAC::~OpenSSLCryptoHashHMAC() {

	if (m_initialised)
		HMAC_CTX_cleanup(&m_hctx);

}


// Hashing Activities

void OpenSSLCryptoHashHMAC::reset(void) {

	if (m_initialised) {

		HMAC_CTX_cleanup(&m_hctx);

		HMAC_Init(&m_hctx, 
			m_keyBuf.rawBuffer(),
			m_keyLen,
			mp_md);

	}

}

void OpenSSLCryptoHashHMAC::hash(unsigned char * data, 
								 unsigned int length) {

	if (!m_initialised)
		throw XSECCryptoException(XSECCryptoException::MDError,
			"OpenSSL:HashHMAC - hash called prior to setKey");


	HMAC_Update(&m_hctx, data, (int) length);

}

unsigned int OpenSSLCryptoHashHMAC::finish(unsigned char * hash,
									   unsigned int maxLength) {

	unsigned int retLen;

	// Finish up and copy out hash, returning the length

	HMAC_Final(&m_hctx, m_mdValue, &m_mdLen);

	// Copy to output buffer
	
	retLen = (maxLength > m_mdLen ? m_mdLen : maxLength);
	memcpy(hash, m_mdValue, retLen);

	return retLen;

}

// Get information

XSECCryptoHash::HashType OpenSSLCryptoHashHMAC::getHashType(void) {

	return m_hashType;			// This could be any kind of hash

}

#endif /* HAVE_OPENSSL */