/*
 * Copyright (C) 2011 Sansar Choinyambuu
 * HSR Hochschule fuer Technik Rapperswil
 *
 * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * 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.
 */

#include "imc_attestation_state.h"
#include "imc_attestation_process.h"

#include <imc/imc_agent.h>
#include <pa_tnc/pa_tnc_msg.h>
#include <ietf/ietf_attr.h>
#include <ietf/ietf_attr_pa_tnc_error.h>
#include <ietf/ietf_attr_product_info.h>

#include <libpts.h>

#include <pts/pts_error.h>

#include <tcg/tcg_pts_attr_proto_caps.h>
#include <tcg/tcg_pts_attr_meas_algo.h>
#include <tncif_pa_subtypes.h>

#include <pen/pen.h>
#include <debug.h>
#include <utils/linked_list.h>

/* IMC definitions */

static const char imc_name[] = "Attestation";

#define IMC_VENDOR_ID				PEN_TCG
#define IMC_SUBTYPE					PA_SUBTYPE_TCG_PTS

static imc_agent_t *imc_attestation;

/**
 * Supported PTS measurement algorithms
 */
static pts_meas_algorithms_t supported_algorithms = PTS_MEAS_ALGO_NONE;

/**
 * Supported PTS Diffie Hellman Groups
 */
static pts_dh_group_t supported_dh_groups = PTS_DH_GROUP_NONE;

/**
 * List of buffered Simple Component Evidences
 * To be sent on reception of Generate Attestation Evidence attribute
 */
static linked_list_t *evidences = NULL;

/**
 * Supported PTS Diffie Hellman Groups
 */
static pts_dh_group_t supported_dh_groups = 0;

/**
 * Supported PTS Diffie Hellman Groups
 */
static pts_dh_group_t supported_dh_groups = PTS_DH_GROUP_NONE;

/**
 * List of buffered Simple Component Evidences
 * To be sent on reception of Generate Attestation Evidence attribute
 */
static linked_list_t *evidences = NULL;

/**
 * see section 3.7.1 of TCG TNC IF-IMC Specification 1.2
 */
TNC_Result TNC_IMC_Initialize(TNC_IMCID imc_id,
							  TNC_Version min_version,
							  TNC_Version max_version,
							  TNC_Version *actual_version)
{
	if (imc_attestation)
	{
		DBG1(DBG_IMC, "IMC \"%s\" has already been initialized", imc_name);
		return TNC_RESULT_ALREADY_INITIALIZED;
	}
	if (!pts_meas_algo_probe(&supported_algorithms) ||
		!pts_dh_group_probe(&supported_dh_groups))
	{
		return TNC_RESULT_FATAL;
	}
	imc_attestation = imc_agent_create(imc_name, IMC_VENDOR_ID, IMC_SUBTYPE,
									   imc_id, actual_version);
	if (!imc_attestation)
	{
		return TNC_RESULT_FATAL;
	}

	libpts_init();
	
	if (min_version > TNC_IFIMC_VERSION_1 || max_version < TNC_IFIMC_VERSION_1)
	{
		DBG1(DBG_IMC, "no common IF-IMC version");
		return TNC_RESULT_NO_COMMON_VERSION;
	}
	return TNC_RESULT_SUCCESS;
}

/**
 * see section 3.7.2 of TCG TNC IF-IMC Specification 1.2
 */
TNC_Result TNC_IMC_NotifyConnectionChange(TNC_IMCID imc_id,
										  TNC_ConnectionID connection_id,
										  TNC_ConnectionState new_state)
{
	imc_state_t *state;

	if (!imc_attestation)
	{
		DBG1(DBG_IMC, "IMC \"%s\" has not been initialized", imc_name);
		return TNC_RESULT_NOT_INITIALIZED;
	}
	switch (new_state)
	{
		case TNC_CONNECTION_STATE_CREATE:
			state = imc_attestation_state_create(connection_id);
			return imc_attestation->create_state(imc_attestation, state);
		case TNC_CONNECTION_STATE_DELETE:
			return imc_attestation->delete_state(imc_attestation, connection_id);
		case TNC_CONNECTION_STATE_HANDSHAKE:
		case TNC_CONNECTION_STATE_ACCESS_ISOLATED:
		case TNC_CONNECTION_STATE_ACCESS_NONE:
		default:
			return imc_attestation->change_state(imc_attestation, connection_id,
												  new_state, NULL);
	}
}


/**
 * see section 3.7.3 of TCG TNC IF-IMC Specification 1.2
 */
TNC_Result TNC_IMC_BeginHandshake(TNC_IMCID imc_id,
								  TNC_ConnectionID connection_id)
{
	imc_state_t *state;
	imc_attestation_state_t *attestation_state;
	pts_t *pts;
	char *platform_info;
	TNC_Result result = TNC_RESULT_SUCCESS;

	if (!imc_attestation)
	{
		DBG1(DBG_IMC, "IMC \"%s\" has not been initialized", imc_name);
		return TNC_RESULT_NOT_INITIALIZED;
	}

	/* get current IMC state */
	if (!imc_attestation->get_state(imc_attestation, connection_id, &state))
	{
		return TNC_RESULT_FATAL;
	}
	attestation_state = (imc_attestation_state_t*)state;
	pts = attestation_state->get_pts(attestation_state);

	platform_info = pts->get_platform_info(pts);
	if (platform_info)
	{
		pa_tnc_msg_t *pa_tnc_msg;
		pa_tnc_attr_t *attr;

		pa_tnc_msg = pa_tnc_msg_create();
		attr = ietf_attr_product_info_create(0, 0, platform_info);
		pa_tnc_msg->add_attribute(pa_tnc_msg, attr);
		pa_tnc_msg->build(pa_tnc_msg);
		result = imc_attestation->send_message(imc_attestation, connection_id,
									pa_tnc_msg->get_encoding(pa_tnc_msg));
		pa_tnc_msg->destroy(pa_tnc_msg);
	}

	return result;
}

/**
 * see section 3.7.4 of TCG TNC IF-IMC Specification 1.2
 */
TNC_Result TNC_IMC_ReceiveMessage(TNC_IMCID imc_id,
								  TNC_ConnectionID connection_id,
								  TNC_BufferReference msg,
								  TNC_UInt32 msg_len,
								  TNC_MessageType msg_type)
{
	pa_tnc_msg_t *pa_tnc_msg;
	pa_tnc_attr_t *attr;
	linked_list_t *attr_list;
	imc_state_t *state;
	imc_attestation_state_t *attestation_state;
	enumerator_t *enumerator;
	TNC_Result result;

	if (!imc_attestation)
	{
		DBG1(DBG_IMC, "IMC \"%s\" has not been initialized", imc_name);
		return TNC_RESULT_NOT_INITIALIZED;
	}

	/* get current IMC state */
	if (!imc_attestation->get_state(imc_attestation, connection_id, &state))
	{
		return TNC_RESULT_FATAL;
	}
	attestation_state = (imc_attestation_state_t*)state;

	/* parse received PA-TNC message and automatically handle any errors */
	result = imc_attestation->receive_message(imc_attestation, connection_id,
									   chunk_create(msg, msg_len), msg_type,
									   &pa_tnc_msg);

	/* no parsed PA-TNC attributes available if an error occurred */
	if (!pa_tnc_msg)
	{
		return result;
	}
	
	attr_list = linked_list_create();
	result = TNC_RESULT_SUCCESS;

	/* analyze PA-TNC attributes */
	enumerator = pa_tnc_msg->create_attribute_enumerator(pa_tnc_msg);
	while (enumerator->enumerate(enumerator, &attr))
	{
		if (attr->get_vendor_id(attr) == PEN_IETF &&
			attr->get_type(attr) == IETF_ATTR_PA_TNC_ERROR)
		{
			ietf_attr_pa_tnc_error_t *error_attr;
			pa_tnc_error_code_t error_code;
			chunk_t msg_info, attr_info;
			u_int32_t offset;

			error_attr = (ietf_attr_pa_tnc_error_t*)attr;
			error_code = error_attr->get_error_code(error_attr);
			msg_info = error_attr->get_msg_info(error_attr);

			DBG1(DBG_IMC, "received PA-TNC error '%N' concerning message %#B",
				 pa_tnc_error_code_names, error_code, &msg_info);
			switch (error_code)
			{
				case PA_ERROR_INVALID_PARAMETER:
					offset = error_attr->get_offset(error_attr);
					DBG1(DBG_IMC, "  occurred at offset of %u bytes", offset);
					break;
				case PA_ERROR_ATTR_TYPE_NOT_SUPPORTED:
					attr_info = error_attr->get_attr_info(error_attr);
					DBG1(DBG_IMC, "  unsupported attribute %#B", &attr_info);
					break;
				default:
					break;
			}
			result = TNC_RESULT_FATAL;
		}
		else if (attr->get_vendor_id(attr) == PEN_TCG)
		{
			if (!imc_attestation_process(attr, attr_list, attestation_state,
				supported_algorithms, supported_dh_groups))
			{
				result = TNC_RESULT_FATAL;
			}
		}
	}
	enumerator->destroy(enumerator);
	pa_tnc_msg->destroy(pa_tnc_msg);

	if (result == TNC_RESULT_SUCCESS && attr_list->get_count(attr_list))
	{
		pa_tnc_msg = pa_tnc_msg_create();

		enumerator = attr_list->create_enumerator(attr_list);
		while (enumerator->enumerate(enumerator, &attr))
		{
			pa_tnc_msg->add_attribute(pa_tnc_msg, attr);
		}
		enumerator->destroy(enumerator);

		pa_tnc_msg->build(pa_tnc_msg);
		result = imc_attestation->send_message(imc_attestation, connection_id,
							pa_tnc_msg->get_encoding(pa_tnc_msg));
		pa_tnc_msg->destroy(pa_tnc_msg);
	}

	attr_list->destroy(attr_list);
	return result;
}

/**
 * see section 3.7.5 of TCG TNC IF-IMC Specification 1.2
 */
TNC_Result TNC_IMC_BatchEnding(TNC_IMCID imc_id,
							   TNC_ConnectionID connection_id)
{
	if (!imc_attestation)
	{
		DBG1(DBG_IMC, "IMC \"%s\" has not been initialized", imc_name);
		return TNC_RESULT_NOT_INITIALIZED;
	}
	return TNC_RESULT_SUCCESS;
}

/**
 * see section 3.7.6 of TCG TNC IF-IMC Specification 1.2
 */
TNC_Result TNC_IMC_Terminate(TNC_IMCID imc_id)
{
	if (!imc_attestation)
	{
		DBG1(DBG_IMC, "IMC \"%s\" has not been initialized", imc_name);
		return TNC_RESULT_NOT_INITIALIZED;
	}

	libpts_deinit();

	imc_attestation->destroy(imc_attestation);
	imc_attestation = NULL;

	return TNC_RESULT_SUCCESS;
}

/**
 * see section 4.2.8.1 of TCG TNC IF-IMC Specification 1.2
 */
TNC_Result TNC_IMC_ProvideBindFunction(TNC_IMCID imc_id,
								TNC_TNCC_BindFunctionPointer bind_function)
{
	if (!imc_attestation)
	{
		DBG1(DBG_IMC, "IMC \"%s\" has not been initialized", imc_name);
		return TNC_RESULT_NOT_INITIALIZED;
	}
	return imc_attestation->bind_functions(imc_attestation, bind_function);
}