/**
 * @file ike_sa.c
 *
 * @brief Implementation of ike_sa_t.
 *
 */

/*
 * Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger
 * Copyright (C) 2005-2006 Martin Willi
 * Copyright (C) 2005 Jan Hutter
 * 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 <sys/time.h>
#include <string.h>

#include "ike_sa.h"

#include <types.h>
#include <daemon.h>
#include <definitions.h>
#include <utils/linked_list.h>
#include <utils/logger_manager.h>
#include <crypto/diffie_hellman.h>
#include <crypto/prf_plus.h>
#include <crypto/crypters/crypter.h>
#include <crypto/hashers/hasher.h>
#include <encoding/payloads/sa_payload.h>
#include <encoding/payloads/nonce_payload.h>
#include <encoding/payloads/ke_payload.h>
#include <encoding/payloads/delete_payload.h>
#include <encoding/payloads/transform_substructure.h>
#include <encoding/payloads/transform_attribute.h>
#include <encoding/payloads/ts_payload.h>
#include <sa/transactions/transaction.h>
#include <sa/transactions/ike_sa_init.h>
#include <sa/transactions/delete_ike_sa.h>
#include <sa/transactions/create_child_sa.h>
#include <sa/transactions/delete_child_sa.h>
#include <sa/transactions/dead_peer_detection.h>
#include <queues/jobs/retransmit_request_job.h>
#include <queues/jobs/delete_established_ike_sa_job.h>
#include <queues/jobs/delete_half_open_ike_sa_job.h>
#include <queues/jobs/send_dpd_job.h>
#include <queues/jobs/send_keepalive_job.h>


/**
 * String mappings for ike_sa_state_t.
 */
mapping_t ike_sa_state_m[] = {
	{IKE_CREATED, "CREATED"},
	{IKE_CONNECTING, "CONNECTING"},
	{IKE_ESTABLISHED, "ESTABLISHED"},
	{IKE_DELETING, "DELETING"},
	{MAPPING_END, NULL}
};


typedef struct private_ike_sa_t private_ike_sa_t;

/**
 * Private data of an ike_sa_t object.
 */
struct private_ike_sa_t {

	/**
	 * Public members
	 */
	ike_sa_t public;

	/**
	 * Identifier for the current IKE_SA.
	 */
	ike_sa_id_t *ike_sa_id;
	
	/**
	 * Linked List containing the child sa's of the current IKE_SA.
	 */
	linked_list_t *child_sas;
	
	/**
	 * Current state of the IKE_SA
	 */
	ike_sa_state_t state;
	
	/**
	 * Connection definition used for this IKE_SA
	 */
	connection_t *connection;
	
	/**
	 * Policy definition used for this IKE_SA
	 */
	policy_t *policy;
	
	/**
	 * crypter for inbound traffic
	 */
	crypter_t *crypter_in;
	
	/**
	 * crypter for outbound traffic
	 */
	crypter_t *crypter_out;
	
	/**
	 * Signer for inbound traffic
	 */
	signer_t *signer_in;
	
	/**
	 * Signer for outbound traffic
	 */
	signer_t *signer_out;
	
	/**
	 * Multi purpose prf, set key, use it, forget it
	 */
	prf_t *prf;
	
	/**
	 * Prf function for derivating keymat child SAs
	 */
	prf_t *child_prf;
	
	/**
	 * PRF, with key set to pi_key, used for authentication
	 */
	prf_t *prf_auth_i;

	/**
	 * PRF, with key set to pr_key, used for authentication
	 */
	prf_t *prf_auth_r;
	
	/**
	 * A logger for this IKE_SA.
	 */
	logger_t *logger;
	
	/**
	 * NAT hasher.
	 */
	hasher_t *nat_hasher;
	
	/**
	 * NAT status of local host.
	 */
	bool nat_here;
	
	/**
	 * NAT status of remote host.
	 */
	bool nat_there;
	
	/**
	 * message ID for next outgoung request
	 */
	u_int32_t message_id_out;

	/**
	 * Timestamp of last IKE message received on this SA
	 */
	time_t time_inbound;

	/**
	 * Timestamp of last IKE message sent on this SA
	 */
	time_t time_outbound;
	
	/**
	 * List of queued transactions to process
	 */
	linked_list_t *transaction_queue;
	
	/**
	 * Transaction currently initiated
	 * (only one supported yet, window size = 1)
	 */
	transaction_t *transaction_out;
	
	/**
	 * last transaction initiated by peer processed.
	 * (only one supported yet, window size = 1)
	 * Stored for retransmission.
	 */
	transaction_t *transaction_in;
	
	/**
	 * Next incoming transaction expected. Used to
	 * do multi transaction operations.
	 */
	transaction_t *transaction_in_next;
};

/**
 * get the time of the latest traffic processed by the kernel
 */
static time_t get_esp_time(private_ike_sa_t* this, bool inbound)
{
	iterator_t *iterator;
	child_sa_t *child_sa;
	time_t latest = 0, use_time;
	
	iterator = this->child_sas->create_iterator(this->child_sas, TRUE);
	while (iterator->iterate(iterator, (void**)&child_sa))
	{
		if (child_sa->get_use_time(child_sa, inbound, &use_time) == SUCCESS)
		{
			latest = max(latest, use_time);
		}
	}
	iterator->destroy(iterator);
	
	return latest;
}

/**
 * get the time of the latest received traffice
 */
static time_t get_time_inbound(private_ike_sa_t *this)
{
	return max(this->time_inbound, get_esp_time(this, TRUE));
}

/**
 * get the time of the latest sent traffic
 */
static time_t get_time_outbound(private_ike_sa_t *this)
{
	return max(this->time_outbound, get_esp_time(this, FALSE));
}


/**
 * Update connection host, as addresses may change (NAT)
 */
static void update_hosts(private_ike_sa_t *this, host_t *me, host_t *other)
{
	/*
	 * Quoting RFC 4306:
	 *
	 * 2.11.  Address and Port Agility
	 * 
	 *    IKE runs over UDP ports 500 and 4500, and implicitly sets up ESP and
	 *    AH associations for the same IP addresses it runs over.  The IP
	 *    addresses and ports in the outer header are, however, not themselves
	 *    cryptographically protected, and IKE is designed to work even through
	 *    Network Address Translation (NAT) boxes.  An implementation MUST
	 *    accept incoming requests even if the source port is not 500 or 4500,
	 *    and MUST respond to the address and port from which the request was
	 *    received.  It MUST specify the address and port at which the request
	 *    was received as the source address and port in the response.  IKE
	 *    functions identically over IPv4 or IPv6.
	 *
	 *    [...]
	 *
	 *    There are cases where a NAT box decides to remove mappings that
	 *    are still alive (for example, the keepalive interval is too long,
	 *    or the NAT box is rebooted).  To recover in these cases, hosts
	 *    that are not behind a NAT SHOULD send all packets (including
	 *    retransmission packets) to the IP address and port from the last
	 *    valid authenticated packet from the other end (i.e., dynamically
	 *    update the address).  A host behind a NAT SHOULD NOT do this
	 *    because it opens a DoS attack possibility.  Any authenticated IKE
	 *    packet or any authenticated UDP-encapsulated ESP packet can be
	 *    used to detect that the IP address or the port has changed.
	 */
	host_t *old_other = NULL;
	iterator_t *iterator = NULL;
	child_sa_t *child_sa = NULL;
	int my_changes, other_changes;

	my_changes = me->get_differences(me, this->connection->get_my_host(this->connection));

	old_other = this->connection->get_other_host(this->connection);
	other_changes = other->get_differences(other, old_other);

	if (!my_changes && !other_changes) 
	{
		return;
	}
	
	if (my_changes)
	{
		this->connection->update_my_host(this->connection, me->clone(me));
	}
	
	if (!this->nat_here)
	{
		/* update without restrictions if we are not NATted */
		if (other_changes)
		{
			this->connection->update_other_host(this->connection, other->clone(other));
		}
	}
	else
	{
		/* if we are natted, only port may change */
		if (other_changes & HOST_DIFF_ADDR)
		{
			return;
		}
		else if (other_changes & HOST_DIFF_PORT)
		{
			old_other->set_port(old_other, other->get_port(other));
		}
	}
	iterator = this->child_sas->create_iterator(this->child_sas, TRUE);
	while (iterator->iterate(iterator, (void**)&child_sa))
	{
		child_sa->update_hosts(child_sa,
							   this->connection->get_my_host(this->connection),
							   this->connection->get_other_host(this->connection),
							   my_changes, other_changes);
		/* TODO: what to do if update fails? Delete CHILD_SA? */
	}
	iterator->destroy(iterator);
}

/**
 * send a request and schedule retransmission
 */
static status_t transmit_request(private_ike_sa_t *this)
{
	message_t *request;
	packet_t *packet;
	status_t status;
	retransmit_request_job_t *job;
	u_int32_t transmitted;
	u_int32_t timeout;
	transaction_t *transaction = this->transaction_out;
	u_int32_t message_id = transaction->get_message_id(transaction);
	
	transmitted = transaction->requested(transaction);
	timeout = charon->configuration->get_retransmit_timeout(charon->configuration,
															transmitted);
	if (timeout == 0)
	{
		this->logger->log(this->logger, ERROR,
						  "giving up after %d retransmits, deleting IKE_SA",
						  transmitted - 1);
		return DESTROY_ME;
	}
	
	status = transaction->get_request(transaction, &request);
	if (status != SUCCESS)
	{
		return status;
	}
	/* if we retransmit, the request is already generated */
	if (transmitted == 0)
	{
		status = request->generate(request, this->crypter_out, this->signer_out, &packet);
		if (status != SUCCESS)
		{
			return FAILED;
		}
	}
	else
	{
		this->logger->log(this->logger, CONTROL, 
						  "sending retransmit %d for %s request with message ID %d",
						  transmitted,
						  mapping_find(exchange_type_m, request->get_exchange_type(request)),
						  message_id);
		packet = request->get_packet(request);
	}
	/* finally send */
	charon->send_queue->add(charon->send_queue, packet);
	this->time_outbound = time(NULL);
	
	/* schedule retransmission job */
	job = retransmit_request_job_create(message_id, this->ike_sa_id);
	charon->event_queue->add_relative(charon->event_queue, (job_t*)job, timeout);
	return SUCCESS;
}

/**
 * Implementation of ike_sa.retransmit_request.
 */
static status_t retransmit_request(private_ike_sa_t *this, u_int32_t message_id)
{
	if (this->transaction_out == NULL ||
		this->transaction_out->get_message_id(this->transaction_out) != message_id)
	{
		/* no retransmit necessary, transaction did already complete */
		return SUCCESS;
	}
	return transmit_request(this);
}

/**
 * Check for transactions in the queue and initiate the first transaction found.
 */
static status_t process_transaction_queue(private_ike_sa_t *this)
{
	if (this->transaction_out)
	{
		/* already a transaction in progress */
		return SUCCESS;
	}
	
	while (TRUE)
	{
		if (this->transaction_queue->remove_first(this->transaction_queue,
			(void**)&this->transaction_out) != SUCCESS)
		{
			/* transaction queue empty */
			return SUCCESS;
		}
		switch (transmit_request(this))
		{
			case SUCCESS:
				return SUCCESS;
			case DESTROY_ME:
				/* critical, IKE_SA unusable, destroy immediately */
				this->logger->log(this->logger, ERROR, 
								  "transaction initiaton failed, deleting IKE_SA");
				return DESTROY_ME;
			default:
				/* discard transaction, process next one */
				this->logger->log(this->logger, ERROR, 
								  "transaction initiation failed, discarded");
				this->transaction_out->destroy(this->transaction_out);
				this->transaction_out = NULL;
				/* handle next transaction */
				continue;
		}
	}
}

/**
 * Queue a new transaction and execute the next outstanding transaction
 */
static status_t queue_transaction(private_ike_sa_t *this, transaction_t *transaction, bool prefer)
{
	/* inject next transaction */
	if (transaction)
	{
		if (prefer)
		{
			this->transaction_queue->insert_first(this->transaction_queue, transaction);
		}
		else
		{
			this->transaction_queue->insert_last(this->transaction_queue, transaction);
		}
	}
	/* process a transaction */
	return process_transaction_queue(this);
}

/**
 * process an incoming request.
 */
static status_t process_request(private_ike_sa_t *this, message_t *request)
{
	transaction_t *last, *current = NULL;
	message_t *response;
	packet_t *packet;
	u_int32_t request_mid;
	status_t status;
	
	request_mid = request->get_message_id(request);
	last = this->transaction_in;
	
	/* check if message ID is correct */
	if (last)
	{
		u_int32_t last_mid = last->get_message_id(last);
		
		if (last_mid == request_mid)
		{
			/* retransmit detected */
			this->logger->log(this->logger, ERROR,
							  "received retransmitted request for message ID %d, retransmitting response",
							  request_mid);
			last->get_response(last, request, &response, &this->transaction_in_next);
			packet = response->get_packet(response);
			charon->send_queue->add(charon->send_queue, packet);
			this->time_outbound = time(NULL);
			return SUCCESS;
		}
		
		if (last_mid > request_mid)
		{
			/* something seriously wrong here, message id may not decrease */
			this->logger->log(this->logger, ERROR,
							  "received request with message ID %d, excepted %d, ingored",
							  request_mid, last_mid + 1);
			return FAILED;
		}
		/* we allow jumps in message IDs, as long as they are incremental */
		if (last_mid + 1 < request_mid)
		{
			this->logger->log(this->logger, ERROR,
							  "received request with message ID %d, excepted %d",
							  request_mid, last_mid + 1);
		}
	}
	else
	{
		if (request_mid != 0)
		{
			/* warn, but allow it */
			this->logger->log(this->logger, CONTROL,
							  "first received request has message ID %d, excepted 0", 
							  request_mid);
		}
	}
	
	/* check if we already have a pre-created transaction for this request */
	if (this->transaction_in_next)
	{
		current = this->transaction_in_next;
		this->transaction_in_next = NULL;
	}
	else
	{
		current = transaction_create(&this->public, request);
		if (current == NULL)
		{
			this->logger->log(this->logger, ERROR, 
							  "no idea how to handle received message (%d), ignored",
							  request->get_exchange_type(request));
			return FAILED;
		}
	}
	
	/* send message. get_request() always gives a valid response */
	status = current->get_response(current, request, &response, &this->transaction_in_next);
	if (response->generate(response, this->crypter_out, this->signer_out, &packet) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, 
						  "response generation failed, discarding transaction");
		current->destroy(current);
		return FAILED;
	}
	
	charon->send_queue->add(charon->send_queue, packet);
	this->time_outbound = time(NULL);
	/* act depending on transaction result */
	switch (status)
	{
		case DESTROY_ME:
			/* transactions says we should destroy the IKE_SA, so do it */
			current->destroy(current);
			return DESTROY_ME;
		default:
			/* store for retransmission, destroy old transaction */
			this->transaction_in = current;
			if (last)
			{
				last->destroy(last);
			}
			return SUCCESS;
	}
}

/**
 * process an incoming response
 */
static status_t process_response(private_ike_sa_t *this, message_t *response)
{
	transaction_t *current, *new = NULL;
	
	current = this->transaction_out;
	/* check if message ID is that of our currently active transaction */
	if (current == NULL ||
		current->get_message_id(current) !=
		   response->get_message_id(response))
	{
		this->logger->log(this->logger, ERROR, 
						  "received response with message ID %d not requested, ignored");
		return FAILED;
	}
	
	switch (current->conclude(current, response, &new))
	{
		case DESTROY_ME:
			/* state requested to destroy IKE_SA */
			return DESTROY_ME;
		default:
			/* discard transaction, process next one */
			break;
	}
	/* transaction comleted, remove */
	current->destroy(current);
	this->transaction_out = NULL;
	
	/* queue new transaction */
	return queue_transaction(this, new, TRUE);
}

/**
 * send a notify back to the sender
 */
static void send_notify_response(private_ike_sa_t *this,
								 message_t *request,
								 notify_type_t type)
{
	notify_payload_t *notify;
	message_t *response;
	host_t *src, *dst;
	packet_t *packet;
	
	response = message_create();
	dst = request->get_source(request);
	src = request->get_destination(request);
	response->set_source(response, src->clone(src));
	response->set_destination(response, dst->clone(dst));
	response->set_exchange_type(response, request->get_exchange_type(request));
	response->set_request(response, FALSE);
	response->set_message_id(response, request->get_message_id(request));
	response->set_ike_sa_id(response, this->ike_sa_id);
	notify = notify_payload_create_from_protocol_and_type(PROTO_NONE, type);
	response->add_payload(response, (payload_t *)notify);
	if (response->generate(response, this->crypter_out, this->signer_out, &packet) != SUCCESS)
	{
		response->destroy(response);
		return;
	}
	charon->send_queue->add(charon->send_queue, packet);
	this->time_outbound = time(NULL);
	response->destroy(response);
	return;
}


/**
 * Implementation of ike_sa_t.process_message.
 */
static status_t process_message(private_ike_sa_t *this, message_t *message)
{
	status_t status;
	bool is_request;
	
	is_request = message->get_request(message);
	
	status = message->parse_body(message, this->crypter_in, this->signer_in);
	if (status != SUCCESS)
	{
		switch (status)
		{
			case NOT_SUPPORTED:
				this->logger->log(this->logger, ERROR,
								  "ciritcal unknown payloads found");
				if (is_request)
				{
					send_notify_response(this, message, UNSUPPORTED_CRITICAL_PAYLOAD);
				}
				break;
			case PARSE_ERROR:
				this->logger->log(this->logger, ERROR,
								  "message parsing failed");
				if (is_request)
				{
					send_notify_response(this, message, INVALID_SYNTAX);
				}
				break;
			case VERIFY_ERROR:
				this->logger->log(this->logger, ERROR,
								  "message verification failed");
				if (is_request)
				{
					send_notify_response(this, message, INVALID_SYNTAX);
				}
				break;
			case FAILED:
				this->logger->log(this->logger, ERROR,
								  "integrity check failed");
				/* ignored */
				break;
			case INVALID_STATE:
				this->logger->log(this->logger, ERROR,
								  "found encrypted message, but no keys available");
				if (is_request)
				{
					send_notify_response(this, message, INVALID_SYNTAX);
				}
			default:
				break;
		}
		this->logger->log(this->logger, ERROR,
						  "%s %s with message ID %d processing failed",
						  mapping_find(exchange_type_m, message->get_exchange_type(message)),
						  message->get_request(message) ? "request" : "response",
						  message->get_message_id(message));
	}
	else
	{
		/* check if message is trustworthy, and update connection information */
		if ((this->state == IKE_CREATED && this->connection) ||
			message->get_exchange_type(message) != IKE_SA_INIT)
		{
			update_hosts(this, message->get_destination(message),
							   message->get_source(message));
			this->time_inbound = time(NULL);
		}
		if (is_request)
		{
			status = process_request(this, message);
		}
		else
		{
			status = process_response(this, message);
		}
	}
	return status;
}

/**
 * Implementation of ike_sa_t.initiate.
 */
static status_t initiate(private_ike_sa_t *this, connection_t *connection)
{
	ike_sa_init_t *ike_sa_init;
	
	/* set connection and policy */
	this->connection = connection;
	this->policy = charon->policies->get_policy_by_name(charon->policies,
			this->connection->get_name(this->connection));
	if (this->policy == NULL)
	{
		this->logger->log(this->logger, ERROR,
						  "no policy found for connection %s, aborting",
						  connection->get_name(connection));
		return DESTROY_ME;
	}
	this->message_id_out = 1;
	ike_sa_init = ike_sa_init_create(&this->public);
	return queue_transaction(this, (transaction_t*)ike_sa_init, TRUE);
}

/**
 * Implementation of ike_sa_t.send_dpd
 */
static status_t send_dpd(private_ike_sa_t *this)
{
	send_dpd_job_t *job;
	time_t diff, interval;
	status_t status = SUCCESS;
	
	interval = charon->configuration->get_dpd_interval(charon->configuration);
	
	if (this->transaction_out)
	{
		/* there is a transaction in progress. Come back later */
		diff = 0;
	}
	else
	{
		/* check if there was any inbound traffic */
		time_t last_in, now;
		last_in = get_time_inbound(this);
		now = time(NULL);
		diff = now - last_in;
		if (diff >= interval)
		{
			/* to long ago, initiate dead peer detection */
			dead_peer_detection_t *dpd;
			this->logger->log(this->logger, CONTROL, "sending DPD request");
			dpd = dead_peer_detection_create(&this->public);
			status = queue_transaction(this, (transaction_t*)dpd, FALSE);
			diff = 0;
		}
	}
	/* recheck in "interval" seconds */
	job = send_dpd_job_create(this->ike_sa_id);
	charon->event_queue->add_relative(charon->event_queue, (job_t*)job,
									  (interval - diff) * 1000);
	return SUCCESS;
}

/**
 * Implementation of ike_sa_t.send_keepalive
 */
static void send_keepalive(private_ike_sa_t *this)
{
	send_keepalive_job_t *job;
	time_t last_out, now, diff, interval;
	
	last_out = get_time_outbound(this);
	now = time(NULL);
	
	diff = now - last_out;
	interval = charon->configuration->get_keepalive_interval(charon->configuration);
	
	if (diff >= interval)
	{
		host_t *me, *other;
		packet_t *packet;
		chunk_t data;
		
		packet = packet_create();
		me = this->connection->get_my_host(this->connection);
		other = this->connection->get_other_host(this->connection);
		packet->set_source(packet, me->clone(me));
		packet->set_destination(packet, other->clone(other));
		data.ptr = malloc(1);
		data.ptr[0] = 0xFF;
		data.len = 1;
		packet->set_data(packet, data);
		charon->send_queue->add(charon->send_queue, packet);
		this->logger->log(this->logger, CONTROL, "sending keep alive");
		diff = 0;
	}
	job = send_keepalive_job_create(this->ike_sa_id);
	charon->event_queue->add_relative(charon->event_queue, (job_t*)job,
									  (interval - diff) * 1000);
}

/**
 * Implementation of ike_sa_t.get_state.
 */
static ike_sa_state_t get_state(private_ike_sa_t *this)
{
	return this->state;
}

/**
 * Implementation of ike_sa_t.set_state.
 */
static void set_state(private_ike_sa_t *this, ike_sa_state_t state)
{
	this->logger->log(this->logger, CONTROL, "state change: %s => %s",
					  mapping_find(ike_sa_state_m, this->state),
					  mapping_find(ike_sa_state_m, state));
	if (state == IKE_ESTABLISHED)
	{
		host_t *my_host, *other_host;
		identification_t *my_id, *other_id;
		my_host = this->connection->get_my_host(this->connection);
		other_host = this->connection->get_other_host(this->connection);
		my_id = this->policy->get_my_id(this->policy);
		other_id = this->policy->get_other_id(this->policy);
		this->logger->log(this->logger, AUDIT, "IKE_SA established: %s[%s]...%s[%s]",
						  my_host->get_address(my_host),
						  my_id->get_string(my_id),
						  other_host->get_address(other_host),
						  other_id->get_string(other_id));
		
		send_dpd(this);
	}
	this->state = state;
}

/**
 * Implementation of protected_ike_sa_t.get_connection.
 */
static connection_t *get_connection(private_ike_sa_t *this)
{
	return this->connection;
}

/**
 * Implementation of protected_ike_sa_t.set_connection.
 */
static void set_connection(private_ike_sa_t *this,connection_t * connection)
{
	this->connection = connection;
}

/**
 * Implementation of protected_ike_sa_t.get_policy.
 */
static policy_t *get_policy(private_ike_sa_t *this)
{
	return this->policy;
}

/**
 * Implementation of protected_ike_sa_t.set_policy.
 */
static void set_policy(private_ike_sa_t *this,policy_t * policy)
{
	this->policy = policy;
}

/**
 * Implementation of protected_ike_sa_t.get_prf.
 */
static prf_t *get_prf(private_ike_sa_t *this)
{
	return this->prf;
}

/**
 * Implementation of protected_ike_sa_t.get_prf.
 */
static prf_t *get_child_prf(private_ike_sa_t *this)
{
	return this->child_prf;
}

/**
 * Implementation of protected_ike_sa_t.get_prf_auth_i.
 */
static prf_t *get_prf_auth_i(private_ike_sa_t *this)
{
	return this->prf_auth_i;
}

/**
 * Implementation of protected_ike_sa_t.get_prf_auth_r.
 */
static prf_t *get_prf_auth_r(private_ike_sa_t *this)
{
	return this->prf_auth_r;
}
/**
 * Implementation of ike_sa_t.get_id.
 */
static ike_sa_id_t* get_id(private_ike_sa_t *this)
{
	return this->ike_sa_id;
}

/**
 * Implementation of protected_ike_sa_t.build_transforms.
 */
static status_t build_transforms(private_ike_sa_t *this, proposal_t *proposal, 
								 diffie_hellman_t *dh, chunk_t nonce_i, chunk_t nonce_r,
								 bool initiator)
{
	chunk_t nonces, nonces_spis, skeyseed, key, secret;
	u_int64_t spi_i, spi_r;
	prf_plus_t *prf_plus;
	algorithm_t *algo;
	size_t key_size;
	crypter_t *crypter_i, *crypter_r;
	signer_t *signer_i, *signer_r;
	
	/* Build the PRF+ instance for deriving keys */
	if (!proposal->get_algorithm(proposal, PSEUDO_RANDOM_FUNCTION, &algo))
	{
		this->logger->log(this->logger, ERROR, "no PSEUDO_RANDOM_FUNCTION selected!");
		return FAILED;
	}
	this->prf = prf_create(algo->algorithm);
	if (this->prf == NULL)
	{
		this->logger->log(this->logger, ERROR, "PSEUDO_RANDOM_FUNCTION %s not supported!",
						  mapping_find(pseudo_random_function_m, algo->algorithm));
		return FAILED;
	}
	
	/* nonces =  nonce_i | nonce_r */
	nonces = chunk_alloc(nonce_i.len + nonce_r.len);
	memcpy(nonces.ptr, nonce_i.ptr, nonce_i.len);
	memcpy(nonces.ptr + nonce_i.len, nonce_r.ptr, nonce_r.len);

	/* prf_seed = nonce_i | nonce_r | spi_i | spi_r */
	nonces_spis = chunk_alloc(nonces.len + 16);
	memcpy(nonces_spis.ptr, nonces.ptr, nonces.len);
	spi_i = this->ike_sa_id->get_initiator_spi(this->ike_sa_id);
	spi_r = this->ike_sa_id->get_responder_spi(this->ike_sa_id);
	memcpy(nonces_spis.ptr + nonces.len, &spi_i, 8);
	memcpy(nonces_spis.ptr + nonces.len + 8, &spi_r, 8);
	
	/* SKEYSEED = prf(Ni | Nr, g^ir) */
	dh->get_shared_secret(dh, &secret);
	this->logger->log_chunk(this->logger, PRIVATE, "shared Diffie Hellman secret", secret);
	this->prf->set_key(this->prf, nonces);
	this->prf->allocate_bytes(this->prf, secret, &skeyseed);
	this->logger->log_chunk(this->logger, PRIVATE|LEVEL1, "SKEYSEED", skeyseed);
	chunk_free(&secret);

	/* prf+ (SKEYSEED, Ni | Nr | SPIi | SPIr )
	 *     = SK_d | SK_ai | SK_ar | SK_ei | SK_er | SK_pi | SK_pr
	 */
	this->prf->set_key(this->prf, skeyseed);
	prf_plus = prf_plus_create(this->prf, nonces_spis);
	
	/* clean up unused stuff */
	chunk_free(&nonces);
	chunk_free(&nonces_spis);
	chunk_free(&skeyseed);
	
	/* SK_d used for prf+ to derive keys for child SAs */
	this->child_prf = prf_create(algo->algorithm);
	key_size = this->child_prf->get_key_size(this->child_prf);
	prf_plus->allocate_bytes(prf_plus, key_size, &key);
	this->logger->log_chunk(this->logger, PRIVATE, "Sk_d secret", key);
	this->child_prf->set_key(this->child_prf, key);
	chunk_free(&key);
	
	/* SK_ai/SK_ar used for integrity protection */
	if (!proposal->get_algorithm(proposal, INTEGRITY_ALGORITHM, &algo))
	{
		this->logger->log(this->logger, ERROR, "no INTEGRITY_ALGORITHM selected?!");
		return FAILED;
	}
	
	signer_i = signer_create(algo->algorithm);
	signer_r = signer_create(algo->algorithm);
	if (signer_i == NULL || signer_r == NULL)
	{
		this->logger->log(this->logger, ERROR, "INTEGRITY_ALGORITHM %s not supported!",
						  mapping_find(integrity_algorithm_m,algo->algorithm));
		return FAILED;
	}
	key_size = signer_i->get_key_size(signer_i);
	
	prf_plus->allocate_bytes(prf_plus, key_size, &key);
	this->logger->log_chunk(this->logger, CONTROL|LEVEL1, "Sk_ai secret", key);
	signer_i->set_key(signer_i, key);
	chunk_free(&key);

	prf_plus->allocate_bytes(prf_plus, key_size, &key);
	this->logger->log_chunk(this->logger, CONTROL|LEVEL1, "Sk_ar secret", key);
	signer_r->set_key(signer_r, key);
	chunk_free(&key);
	
	if (initiator)
	{
		this->signer_in = signer_r;
		this->signer_out = signer_i;
	}
	else
	{
		this->signer_in = signer_i;
		this->signer_out = signer_r;
	}
	
	/* SK_ei/SK_er used for encryption */
	if (!proposal->get_algorithm(proposal, ENCRYPTION_ALGORITHM, &algo))
	{
		this->logger->log(this->logger, ERROR, "no ENCRYPTION_ALGORITHM selected!");
		return FAILED;
	}	
	crypter_i = crypter_create(algo->algorithm, algo->key_size / 8);
	crypter_r = crypter_create(algo->algorithm, algo->key_size / 8);
	if (crypter_i == NULL || crypter_r == NULL)
	{
		this->logger->log(this->logger, ERROR, 
						  "ENCRYPTION_ALGORITHM %s (key size %d) not supported!",
						  mapping_find(encryption_algorithm_m, algo->algorithm),
						  algo->key_size);
		return FAILED;
	}
	key_size = crypter_i->get_key_size(crypter_i);
	
	prf_plus->allocate_bytes(prf_plus, key_size, &key);
	this->logger->log_chunk(this->logger, PRIVATE, "Sk_ei secret", key);
	crypter_i->set_key(crypter_i, key);
	chunk_free(&key);
	
	prf_plus->allocate_bytes(prf_plus, key_size, &key);
	this->logger->log_chunk(this->logger, PRIVATE, "Sk_er secret", key);
	crypter_r->set_key(crypter_r, key);
	chunk_free(&key);
	
	if (initiator)
	{
		this->crypter_in = crypter_r;
		this->crypter_out = crypter_i;
	}
	else
	{
		this->crypter_in = crypter_i;
		this->crypter_out = crypter_r;
	}
	
	/* SK_pi/SK_pr used for authentication */	
	proposal->get_algorithm(proposal, PSEUDO_RANDOM_FUNCTION, &algo);
	this->prf_auth_i = prf_create(algo->algorithm);
	this->prf_auth_r = prf_create(algo->algorithm);
	
	key_size = this->prf_auth_i->get_key_size(this->prf_auth_i);
	prf_plus->allocate_bytes(prf_plus, key_size, &key);
	this->logger->log_chunk(this->logger, PRIVATE, "Sk_pi secret", key);
	this->prf_auth_i->set_key(this->prf_auth_i, key);
	chunk_free(&key);
	
	prf_plus->allocate_bytes(prf_plus, key_size, &key);
	this->logger->log_chunk(this->logger, PRIVATE, "Sk_pr secret", key);
	this->prf_auth_r->set_key(this->prf_auth_r, key);
	chunk_free(&key);
	
	/* all done, prf_plus not needed anymore */
	prf_plus->destroy(prf_plus);
	
	return SUCCESS;
}

/**
 * Implementation of protected_ike_sa_t.add_child_sa.
 */
static void add_child_sa(private_ike_sa_t *this, child_sa_t *child_sa)
{
	this->child_sas->insert_last(this->child_sas, child_sa);
}

/**
 * Implementation of protected_ike_sa_t.get_child_sa.
 */
static child_sa_t* get_child_sa(private_ike_sa_t *this, protocol_id_t protocol,
								u_int32_t spi, bool inbound)
{
	iterator_t *iterator;
	child_sa_t *current, *found = NULL;
	
	iterator = this->child_sas->create_iterator(this->child_sas, FALSE);
	while (iterator->has_next(iterator))
	{
		iterator->current(iterator, (void**)&current);
		if (current->get_spi(current, inbound) == spi &&
				  current->get_protocol(current) == protocol)
		{
			found = current;
		}
	}
	iterator->destroy(iterator);
	return found;
}

/**
 * Implementation of ike_sa_t.rekey_child_sa.
 */
static status_t rekey_child_sa(private_ike_sa_t *this, protocol_id_t protocol, u_int32_t spi)
{
	create_child_sa_t *rekey;
	child_sa_t *child_sa;
	
	child_sa = get_child_sa(this, protocol, spi, TRUE);
	if (child_sa == NULL)
	{
		return NOT_FOUND;
	}
	
	rekey = create_child_sa_create(&this->public);
	rekey->rekeys_child(rekey, child_sa);
	return queue_transaction(this, (transaction_t*)rekey, FALSE);
}

/**
 * Implementation of ike_sa_t.delete_child_sa.
 */
static status_t delete_child_sa(private_ike_sa_t *this, protocol_id_t protocol, u_int32_t spi)
{
	delete_child_sa_t *del;
	child_sa_t *child_sa;
	
	child_sa = get_child_sa(this, protocol, spi, TRUE);
	if (child_sa == NULL)
	{
		return NOT_FOUND;
	}
	
	del = delete_child_sa_create(&this->public);
	del->set_child_sa(del, child_sa);
	return queue_transaction(this, (transaction_t*)del, FALSE);
}

/**
 * Implementation of protected_ike_sa_t.destroy_child_sa.
 */
static status_t destroy_child_sa(private_ike_sa_t *this, protocol_id_t protocol, u_int32_t spi)
{
	iterator_t *iterator;
	child_sa_t *child_sa;
	status_t status = NOT_FOUND;
	
	iterator = this->child_sas->create_iterator(this->child_sas, TRUE);
	while (iterator->iterate(iterator, (void**)&child_sa))
	{
		if (child_sa->get_protocol(child_sa) == protocol &&
			child_sa->get_spi(child_sa, TRUE) == spi)
		{
			child_sa->destroy(child_sa);
			iterator->remove(iterator);
			status = SUCCESS;
			break;
		}
	}
	iterator->destroy(iterator);
	return status;
}


/**
 * Implementation of protected_ike_sa_t.log_status.
 */
static void log_status(private_ike_sa_t *this, logger_t *logger, char *name)
{
	iterator_t *iterator;
	child_sa_t *child_sa;
	host_t *my_host, *other_host;
	identification_t *my_id = NULL, *other_id = NULL;
	
	/* only log if name == NULL or name == connection_name */
	if (name)
	{
		if (streq(this->connection->get_name(this->connection), name))
		{
			return;
		}
	}
	my_host = this->connection->get_my_host(this->connection);
	other_host = this->connection->get_other_host(this->connection);

	/* use policy information, if available */
	if (this->policy)
	{
		my_id = this->policy->get_my_id(this->policy);
		other_id = this->policy->get_other_id(this->policy);
		name = this->policy->get_name(this->policy);
	}
	else
	{
		name = this->connection->get_name(this->connection);
	}
	
	if (logger == NULL)
	{
		logger = this->logger;
	}
	logger->log(logger, CONTROL|LEVEL1, "  \"%s\": IKE_SA in state %s, SPIs: 0x%.16llx 0x%.16llx",
				name,
				mapping_find(ike_sa_state_m, this->state),
				this->ike_sa_id->get_initiator_spi(this->ike_sa_id),
				this->ike_sa_id->get_responder_spi(this->ike_sa_id));
	logger->log(logger, CONTROL, "  \"%s\": %s[%s]...%s[%s]",
				name,
				my_host->get_address(my_host),
				my_id ? my_id->get_string(my_id) : "(unknown)",
				other_host->get_address(other_host),
				other_id ? other_id->get_string(other_id) : "(unknown)");
	
	iterator = this->child_sas->create_iterator(this->child_sas, TRUE);
	while (iterator->has_next(iterator))
	{
		iterator->current(iterator, (void**)&child_sa);
		child_sa->log_status(child_sa, logger, name);
	}
	iterator->destroy(iterator);
}

/**
 * Implementation of public_ike_sa_t.delete.
 */
static status_t delete_(private_ike_sa_t *this)
{
	delete_ike_sa_t *delete_ike_sa;
	delete_ike_sa = delete_ike_sa_create(&this->public);
	
	if (this->transaction_out)
	{
		/* already a transaction in progress. As this may hang
		 * around a while, we don't inform the other peer. */
		return DESTROY_ME;
	}
	
	return queue_transaction(this, (transaction_t*)delete_ike_sa, FALSE);
}

/**
 * Implementation of ike_sa_t.get_next_message_id.
 */
static u_int32_t get_next_message_id (private_ike_sa_t *this)
{
	return this->message_id_out++;
}

/**
 * Implementation of ike_sa_t.is_natt_enabled.
 */
static bool is_natt_enabled (private_ike_sa_t *this)
{
	return this->nat_here || this->nat_there;
}

/**
 * Implementation of protected_ike_sa_t.enable_natt.
 */
static void enable_natt (private_ike_sa_t *this, bool local)
{
	if (local)
	{
		this->logger->log(this->logger, CONTROL,
						  "local host is behind NAT, using NAT-T, scheduled keep alives");
		this->nat_here = TRUE;
		send_keepalive(this);
	}
	else
	{
		this->logger->log(this->logger, CONTROL, 
						  "remote host is behind NAT, using NAT-T");
		this->nat_there = TRUE;
	}
}

/**
 * Implementation of protected_ike_sa_t.destroy.
 */
static void destroy(private_ike_sa_t *this)
{
	child_sa_t *child_sa;
	transaction_t *transaction;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "going to destroy IKE SA %llu:%llu, role %s", 
					  this->ike_sa_id->get_initiator_spi(this->ike_sa_id),
					  this->ike_sa_id->get_responder_spi(this->ike_sa_id),
					  this->ike_sa_id->is_initiator(this->ike_sa_id) ? "initiator" : "responder");
	
	if (this->state == IKE_ESTABLISHED)
	{
		this->logger->log(this->logger, ERROR, 
						  "destroying an established IKE SA without knowledge from remote peer!");
	}

	while (this->child_sas->remove_last(this->child_sas, (void**)&child_sa) == SUCCESS)
	{
		child_sa->destroy(child_sa);
	}
	this->child_sas->destroy(this->child_sas);
	
	while (this->transaction_queue->remove_last(this->transaction_queue, (void**)&transaction) == SUCCESS)
	{
		transaction->destroy(transaction);
	}
	this->transaction_queue->destroy(this->transaction_queue);
	if (this->transaction_in)
	{
		this->transaction_in->destroy(this->transaction_in);
	}
	if (this->transaction_in_next)
	{
		this->transaction_in_next->destroy(this->transaction_in_next);
	}
	if (this->transaction_out)
	{
		this->transaction_out->destroy(this->transaction_out);
	}
	if (this->crypter_in)
	{
		this->crypter_in->destroy(this->crypter_in);
	}
	if (this->crypter_out)
	{
		this->crypter_out->destroy(this->crypter_out);
	}
	if (this->signer_in)
	{
		this->signer_in->destroy(this->signer_in);
	}
	if (this->signer_out)
	{
		this->signer_out->destroy(this->signer_out);
	}
	if (this->prf)
	{
		this->prf->destroy(this->prf);
	}
	if (this->child_prf)
	{
		this->child_prf->destroy(this->child_prf);
	}
	if (this->prf_auth_i)
	{
		this->prf_auth_i->destroy(this->prf_auth_i);
	}
	if (this->prf_auth_r)
	{
		this->prf_auth_r->destroy(this->prf_auth_r);
	}
	if (this->connection)
	{
		host_t *my_host, *other_host;
		identification_t *my_id = NULL, *other_id = NULL;
		my_host = this->connection->get_my_host(this->connection);
		other_host = this->connection->get_other_host(this->connection);
		if (this->policy)
		{
			my_id = this->policy->get_my_id(this->policy);
			other_id = this->policy->get_other_id(this->policy);
		}
		
		this->logger->log(this->logger, AUDIT, "IKE_SA deleted between %s[%s]...%s[%s]", 
						  my_host->get_address(my_host),
						  my_id ? my_id->get_string(my_id) : "(unknown)",
						  other_host->get_address(other_host),
						  other_id ? other_id->get_string(other_id) : "(unknown)");
		this->connection->destroy(this->connection);
	}
	if (this->policy)
	{
		this->policy->destroy(this->policy);
	}
	this->ike_sa_id->destroy(this->ike_sa_id);
	free(this);
}

/*
 * Described in header.
 */
ike_sa_t * ike_sa_create(ike_sa_id_t *ike_sa_id)
{
	private_ike_sa_t *this = malloc_thing(private_ike_sa_t);
	
	/* Public functions */
	this->public.get_state = (ike_sa_state_t(*)(ike_sa_t*)) get_state;
	this->public.set_state = (void(*)(ike_sa_t*,ike_sa_state_t)) set_state;
	this->public.process_message = (status_t(*)(ike_sa_t*, message_t*)) process_message;
	this->public.initiate = (status_t(*)(ike_sa_t*,connection_t*)) initiate;
	this->public.get_id = (ike_sa_id_t*(*)(ike_sa_t*)) get_id;
	this->public.get_next_message_id = (u_int32_t(*)(ike_sa_t*)) get_next_message_id;
	this->public.get_connection = (connection_t*(*)(ike_sa_t*)) get_connection;
	this->public.retransmit_request = (status_t (*) (ike_sa_t *, u_int32_t)) retransmit_request;
	this->public.log_status = (void (*) (ike_sa_t*,logger_t*,char*))log_status;
	this->public.delete = (status_t(*)(ike_sa_t*))delete_;
	this->public.destroy = (void(*)(ike_sa_t*))destroy;
	this->public.send_dpd = (status_t (*)(ike_sa_t*)) send_dpd;
	this->public.send_keepalive = (void (*)(ike_sa_t*)) send_keepalive;
	this->public.get_prf = (prf_t *(*) (ike_sa_t *)) get_prf;
	this->public.get_child_prf = (prf_t *(*) (ike_sa_t *)) get_child_prf;
	this->public.get_prf_auth_i = (prf_t *(*) (ike_sa_t *)) get_prf_auth_i;
	this->public.get_prf_auth_r = (prf_t *(*) (ike_sa_t *)) get_prf_auth_r;
	this->public.set_connection = (void (*) (ike_sa_t *,connection_t *)) set_connection;
	this->public.get_connection = (connection_t *(*) (ike_sa_t *)) get_connection;
	this->public.set_policy = (void (*) (ike_sa_t *,policy_t *)) set_policy;
	this->public.get_policy = (policy_t *(*) (ike_sa_t *)) get_policy;
	this->public.build_transforms = (status_t (*) (ike_sa_t *,proposal_t*,diffie_hellman_t*,chunk_t,chunk_t,bool)) build_transforms;
	this->public.add_child_sa = (void (*) (ike_sa_t*,child_sa_t*)) add_child_sa;
	this->public.get_child_sa = (child_sa_t* (*)(ike_sa_t*,protocol_id_t,u_int32_t,bool)) get_child_sa;
	this->public.rekey_child_sa = (status_t(*)(ike_sa_t*,protocol_id_t,u_int32_t)) rekey_child_sa;
	this->public.delete_child_sa = (status_t(*)(ike_sa_t*,protocol_id_t,u_int32_t)) delete_child_sa;
	this->public.destroy_child_sa = (status_t (*)(ike_sa_t*,protocol_id_t,u_int32_t))destroy_child_sa;
	this->public.enable_natt = (void(*)(ike_sa_t*, bool)) enable_natt;
	this->public.is_natt_enabled = (bool(*)(ike_sa_t*)) is_natt_enabled;
	
	/* initialize private fields */
	this->logger = logger_manager->get_logger(logger_manager, IKE_SA);
	this->ike_sa_id = ike_sa_id->clone(ike_sa_id);
	this->child_sas = linked_list_create();
	this->crypter_in = NULL;
	this->crypter_out = NULL;
	this->signer_in = NULL;
	this->signer_out = NULL;
	this->prf = NULL;
	this->prf_auth_i = NULL;
	this->prf_auth_r = NULL;
 	this->child_prf = NULL;
	this->connection = NULL;
	this->policy = NULL;
	this->nat_here = FALSE;
	this->nat_there = FALSE;
	this->transaction_queue = linked_list_create();
	this->transaction_in = NULL;
	this->transaction_in_next = NULL;
	this->transaction_out = NULL;
	this->state = IKE_CREATED;
	/* we start with message ID out, as ike_sa_init does not use this counter */
	this->message_id_out = 0;
	this->time_inbound = 0;
	this->time_outbound = 0;
	
	return &this->public;
}