[strongswan.git] / src / charon / sa / ike_sa.c

/**
 * @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);
        
        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;
}