/******************************************************************************
 * Icinga 2                                                                   *
 * Copyright (C) 2012 Icinga Development Team (http://www.icinga.org/)        *
 *                                                                            *
 * This program 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             *
 * of the License, or (at your option) any later version.                     *
 *                                                                            *
 * This program 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 this program; if not, write to the Free Software Foundation     *
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ******************************************************************************/

#include "i2-base.h"

using namespace icinga;

int I2_EXPORT TlsClient::m_SSLIndex;
bool I2_EXPORT TlsClient::m_SSLIndexInitialized = false;

/**
 * Constructor for the TlsClient class.
 *
 * @param role The role of the client.
 * @param sslContext The SSL context for the client.
 */
TlsClient::TlsClient(TcpClientRole role, shared_ptr<SSL_CTX> sslContext)
	: TcpClient(role), m_SSLContext(sslContext),
	  m_BlockRead(false), m_BlockWrite(false)
{ }

void TlsClient::Start(void)
{
	m_SSL = shared_ptr<SSL>(SSL_new(m_SSLContext.get()), SSL_free);

	m_SSLContext.reset();

	if (!m_SSL)
		throw_exception(OpenSSLException("SSL_new failed", ERR_get_error()));

	if (!GetClientCertificate())
		throw_exception(logic_error("No X509 client certificate was specified."));

	if (!m_SSLIndexInitialized) {
		m_SSLIndex = SSL_get_ex_new_index(0, (void *)"TlsClient", NULL, NULL, NULL);
		m_SSLIndexInitialized = true;
	}

	SSL_set_ex_data(m_SSL.get(), m_SSLIndex, this);

	SSL_set_verify(m_SSL.get(), SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, NULL);

	SSL_set_fd(m_SSL.get(), GetFD());

	if (GetRole() == RoleInbound)
		SSL_set_accept_state(m_SSL.get());
	else
		SSL_set_connect_state(m_SSL.get());

	int rc = SSL_do_handshake(m_SSL.get());

	if (rc == 1) {
		SetConnected(true);
		OnConnected(GetSelf());
	}

	Socket::Start();
}

/**
 * Takes a certificate as an argument. Does nothing.
 *
 * @param certificate An X509 certificate.
 */
void TlsClient::NullCertificateDeleter(X509 *certificate)
{
	/* Nothing to do here. */
}

/**
 * Retrieves the X509 certficate for this client.
 *
 * @returns The X509 certificate.
 */
shared_ptr<X509> TlsClient::GetClientCertificate(void) const
{
	mutex::scoped_lock lock(GetMutex());

	return shared_ptr<X509>(SSL_get_certificate(m_SSL.get()), &TlsClient::NullCertificateDeleter);
}

/**
 * Retrieves the X509 certficate for the peer.
 *
 * @returns The X509 certificate.
 */
shared_ptr<X509> TlsClient::GetPeerCertificate(void) const
{
	mutex::scoped_lock lock(GetMutex());

	return shared_ptr<X509>(SSL_get_peer_certificate(m_SSL.get()), X509_free);
}

/**
 * Processes data that is available for this socket.
 */
void TlsClient::HandleReadable(void)
{
	int result;

	m_BlockRead = false;
	m_BlockWrite = false;

	result = 0;

	for (;;) {
		char data[1024];
		int rc;

		if (IsConnected()) {
			rc = SSL_read(m_SSL.get(), data, sizeof(data));
		} else {
			rc = SSL_do_handshake(m_SSL.get());

			if (rc == 1) {
				SetConnected(true);
				Event::Post(boost::bind(boost::cref(OnConnected), GetSelf()));
				return;
			}
		}

		if (rc <= 0) {
			switch (SSL_get_error(m_SSL.get(), rc)) {
				case SSL_ERROR_WANT_WRITE:
					m_BlockRead = true;
					/* fall through */
				case SSL_ERROR_WANT_READ:
					goto post_event;
				case SSL_ERROR_ZERO_RETURN:
					CloseInternal(false);
					goto post_event;
				default:
					throw_exception(OpenSSLException("SSL_read failed", ERR_get_error()));
			}
		}

		if (IsConnected())
			m_RecvQueue->Write(data, rc);
	}

post_event:
	Event::Post(boost::bind(boost::ref(OnDataAvailable), GetSelf()));
}

/**
 * Processes data that can be written for this socket.
 */
void TlsClient::HandleWritable(void)
{
	m_BlockRead = false;
	m_BlockWrite = false;

	char data[1024];
	size_t count;

	for (;;) {
		int rc;

		if (IsConnected()) {
			count = m_SendQueue->GetAvailableBytes();

			if (count == 0)
				break;

			if (count > sizeof(data))
				count = sizeof(data);

			m_SendQueue->Peek(data, count);

			rc = SSL_write(m_SSL.get(), (const char *)data, count);
		} else {
			rc = SSL_do_handshake(m_SSL.get());

			if (rc == 1) {
				SetConnected(true);
				Event::Post(boost::bind(boost::cref(OnConnected), GetSelf()));
				return;
			}
		}

		if (rc <= 0) {
			switch (SSL_get_error(m_SSL.get(), rc)) {
				case SSL_ERROR_WANT_READ:
					m_BlockWrite = true;
					/* fall through */
				case SSL_ERROR_WANT_WRITE:
					return;
				case SSL_ERROR_ZERO_RETURN:
					CloseInternal(false);
					return;
				default:
					throw_exception(OpenSSLException("SSL_write failed", ERR_get_error()));
			}
		}

		if (IsConnected())
			m_SendQueue->Read(NULL, rc);
	}
}

/**
 * Checks whether data should be read for this socket.
 *
 * @returns true if data should be read, false otherwise.
 */
bool TlsClient::WantsToRead(void) const
{
	if (SSL_want_read(m_SSL.get()))
		return true;

	if (m_BlockRead)
		return false;

	return TcpClient::WantsToRead();
}

/**
 * Checks whether data should be written for this socket.
 *
 * @returns true if data should be written, false otherwise.
 */
bool TlsClient::WantsToWrite(void) const
{
	if (SSL_want_write(m_SSL.get()))
		return true;

	if (m_BlockWrite)
		return false;

	return TcpClient::WantsToWrite();
}

/**
 * Closes the socket.
 *
 * @param from_dtor Whether this method was invoked from the destructor.
 */
void TlsClient::CloseInternal(bool from_dtor)
{
	if (m_SSL)
		SSL_shutdown(m_SSL.get());

	TcpClient::CloseInternal(from_dtor);
}

/**
 * Factory function for the TlsClient class.
 *
 * @param role The role of the TLS socket.
 * @param sslContext The SSL context for the socket.
 * @returns A new TLS socket.
 */
TcpClient::Ptr icinga::TlsClientFactory(TcpClientRole role, shared_ptr<SSL_CTX> sslContext)
{
	return boost::make_shared<TlsClient>(role, sslContext);
}