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

/**
 * @file connect_manager.c
 *
 * @brief Implementation of connect_manager_t.
 *
 */

/*
 * Copyright (C) 2007 Tobias Brunner
 * 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 "connect_manager.h"

#include <pthread.h>
#include <math.h>

#include <daemon.h>
#include <utils/linked_list.h>
#include <crypto/hashers/hasher.h>

#include <processing/jobs/callback_job.h>
#include <processing/jobs/initiate_mediation_job.h>
#include <encoding/payloads/endpoint_notify.h>

/* base timeout
 * the sending interval is P2P_INTERVAL * active checklists (N)
 * retransmission timeout is P2P_INTERVAL * N * checks in waiting state (NW) */
#define P2P_INTERVAL 20 /* ms */
/* min retransmission timeout (RTO is P2P_INTERVAL * N * checks in waiting state) */
#define P2P_RTO_MIN 100 /* ms */
/* max number of retransmissions (+ the initial check) */
#define P2P_MAX_RETRANS 2


typedef struct private_connect_manager_t private_connect_manager_t;

/**
 * Additional private members of connect_manager_t.
 */
struct private_connect_manager_t {
        /**
         * Public interface of connect_manager_t.
         */
         connect_manager_t public;
        
         /**
          * Lock for exclusivly accessing the manager.
          */
         pthread_mutex_t mutex;
         
         /**
          * Hasher to generate signatures
          */
         hasher_t *hasher;
         
         /**
          * Linked list with initiated mediated connections
          */
         linked_list_t *initiated;
         
         /**
          * Linked list with checklists (hash table with session ID as key would be better).
          */
         linked_list_t *checklists;
};

typedef enum check_state_t check_state_t;

enum check_state_t {
        CHECK_NONE,
        CHECK_WAITING,
        CHECK_IN_PROGRESS,
        CHECK_SUCCEEDED,
        CHECK_FAILED
};

typedef struct endpoint_pair_t endpoint_pair_t;

/**
 * An entry in the check list.
 */
struct endpoint_pair_t {
        /** pair id */
        u_int32_t id;
        
        /** priority */
        u_int64_t priority;
        
        /** local endpoint */
    host_t *local;
    
    /** remote endpoint */
    host_t *remote;
    
    /** state */
    check_state_t state;
    
    /** number of retransmissions */
    u_int32_t retransmitted;
    
    /** the generated packet */
    packet_t *packet;
};

/**
 * Destroys an endpoint pair
 */
static void endpoint_pair_destroy(endpoint_pair_t *this)
{
        DESTROY_IF(this->local);
    DESTROY_IF(this->remote);
    DESTROY_IF(this->packet);
        free(this);
}

/**
 * Creates a new entry for the list.
 */
static endpoint_pair_t *endpoint_pair_create(endpoint_notify_t *initiator,
                endpoint_notify_t *responder, bool initiator_is_local)
{
        endpoint_pair_t *this = malloc_thing(endpoint_pair_t);
        
        this->id = 0;
        
        u_int32_t pi = initiator->get_priority(initiator);
        u_int32_t pr = responder->get_priority(responder);
        this->priority = pow(2, 32) * min(pi, pr) + 2 * max(pi, pr) + (pi > pr ? 1 : 0);
        
        this->local = initiator_is_local ? initiator->get_base(initiator) : responder->get_base(responder);
        this->local = this->local->clone(this->local);
        this->remote = initiator_is_local ? responder->get_host(responder) : initiator->get_host(initiator);
        this->remote = this->remote->clone(this->remote);
        
        this->state = CHECK_WAITING;
        this->retransmitted = 0;
        this->packet = NULL;
    
        return this;
}


typedef struct check_list_t check_list_t;

/**
 * An entry in the linked list.
 */
struct check_list_t {
        
        struct {
                /** initiator's id */
                identification_t *id;
                
                /** initiator's key */
                chunk_t key;
                
                /** initiator's endpoints */
                linked_list_t *endpoints;
        } initiator;
        
        struct {
                /** responder's id */
                identification_t *id;
                
                /** responder's key */
                chunk_t key;
                
                /** responder's endpoints */
                linked_list_t *endpoints;
        } responder;
        
        /** session id */
        chunk_t session_id;
        
    /** list of endpoint pairs */
    linked_list_t *pairs;
    
    /** pairs queued for triggered checks */
    linked_list_t *triggered;
    
    /** state */
    check_state_t state;
    
    /** TRUE if this is the initiator */
        bool is_initiator;
        
};

/**
 * Destroys a checklist
 */
static void check_list_destroy(check_list_t *this)
{
        DESTROY_IF(this->initiator.id);
        DESTROY_IF(this->responder.id);
        
        chunk_free(&this->session_id);
        chunk_free(&this->initiator.key);
        chunk_free(&this->responder.key);
        
        DESTROY_OFFSET_IF(this->initiator.endpoints, offsetof(endpoint_notify_t, destroy));
        DESTROY_OFFSET_IF(this->responder.endpoints, offsetof(endpoint_notify_t, destroy));
        
        DESTROY_FUNCTION_IF(this->pairs, (void*)endpoint_pair_destroy);
        /* this list contains some of the same elements as contained in this->pairs */
        DESTROY_IF(this->triggered); 
        
        free(this);
}

/**
 * Creates a new checklist
 */
static check_list_t *check_list_create(identification_t *initiator, identification_t *responder,
                chunk_t session_id, chunk_t initiator_key, linked_list_t *initiator_endpoints,
                bool is_initiator)
{
        check_list_t *this = malloc_thing(check_list_t);
        
        this->session_id = chunk_clone(session_id);
        
        this->initiator.id = initiator->clone(initiator);
        this->initiator.key = chunk_clone(initiator_key);
        this->initiator.endpoints = initiator_endpoints->clone_offset(initiator_endpoints, offsetof(endpoint_notify_t, clone));
        
        this->responder.id = responder->clone(responder);
        this->responder.key = chunk_empty;
    this->responder.endpoints = NULL;
    
    this->pairs = linked_list_create();
    this->triggered = linked_list_create();
    this->state = CHECK_NONE;
    this->is_initiator = is_initiator;
    
        return this;
}


typedef struct waiting_sa_t waiting_sa_t;

/**
 * For an initiator, the data stored about a waiting mediated sa
 */
struct waiting_sa_t {
        /** ike sa id */
        ike_sa_id_t *ike_sa_id;
        
        /** list of child_cfg_t */
        linked_list_t *childs;
};

/**
 * Destroys a queued mediated sa
 */
static void waiting_sa_destroy(waiting_sa_t *this)
{
        DESTROY_IF(this->ike_sa_id);
        this->childs->destroy_offset(this->childs, offsetof(child_cfg_t, destroy));
        free(this);
}

/**
 * Creates a new mediated sa object
 */
static waiting_sa_t *waiting_sa_create(ike_sa_id_t *ike_sa_id)
{
        waiting_sa_t *this = malloc_thing(waiting_sa_t);
        
        this->ike_sa_id = ike_sa_id->clone(ike_sa_id);
        this->childs = linked_list_create();
    
        return this;
}

typedef struct initiated_t initiated_t;

/**
 * For an initiator, the data stored about initiated mediation connections
 */
struct initiated_t {
        /** my id */
        identification_t *id;
        
        /** peer id */
        identification_t *peer_id;
        
        /** list of mediated sas */
        linked_list_t *mediated;
};

/**
 * Destroys a queued initiation
 */
static void initiated_destroy(initiated_t *this)
{
        DESTROY_IF(this->id);
        DESTROY_IF(this->peer_id);
        this->mediated->destroy_function(this->mediated, (void*)waiting_sa_destroy);
        free(this);
}

/**
 * Creates a queued initiation
 */
static initiated_t *initiated_create(identification_t *id, identification_t *peer_id)
{
        initiated_t *this = malloc_thing(initiated_t);
        
        this->id = id->clone(id);
        this->peer_id = peer_id->clone(peer_id);
        this->mediated = linked_list_create();
    
        return this;
}


typedef struct check_t check_t;

/**
 * Data exchanged in a connectivity check
 */
struct check_t {
        /** message id */
        u_int32_t mid;
        
        /** source of the connectivity check */
        host_t *src;
        
        /** destination of the connectivity check */
        host_t *dst;
        
        /** session id */
        chunk_t session_id;
        
        /** endpoint */
        endpoint_notify_t *endpoint;
        
        /** raw endpoint payload (to verify the signature) */
        chunk_t endpoint_raw;
        
    /** cookie */
    chunk_t cookie;
};

/**
 * Destroys a connectivity check
 */
static void check_destroy(check_t *this)
{
        chunk_free(&this->session_id);
        chunk_free(&this->endpoint_raw);
        chunk_free(&this->cookie);
        DESTROY_IF(this->endpoint);
        free(this);
}

/**
 * Creates a new connectivity check
 */
static check_t *check_create()
{
        check_t *this = malloc_thing(check_t);
        
        this->session_id = chunk_empty;
        this->cookie = chunk_empty;
        this->endpoint_raw = chunk_empty;
        this->endpoint = NULL;
        
        this->mid = 0;
        
        return this;
}

typedef struct sender_data_t sender_data_t;

/**
 * Data required by the sender
 */
struct sender_data_t {
        /** connect manager */
        private_connect_manager_t *connect_manager;
        
        /** session id */
        chunk_t session_id;
};

/**
 * Destroys a sender data object
 */
static void sender_data_destroy(sender_data_t *this)
{
        chunk_free(&this->session_id);
        free(this);
}

/**
 * Creates a new sender data object
 */
static sender_data_t *sender_data_create(private_connect_manager_t *connect_manager, chunk_t session_id)
{
        sender_data_t *this = malloc_thing(sender_data_t);      
        this->connect_manager = connect_manager;
        this->session_id = session_id;
        return this;
}

typedef struct retransmit_data_t retransmit_data_t;

/**
 * Data required by the retransmission job
 */
struct retransmit_data_t {
        /** connect manager */
        private_connect_manager_t *connect_manager;
        
        /** session id */
        chunk_t session_id;
        
        /** message (pair) id */
        u_int32_t mid;
};

/**
 * Destroys a retransmission data object
 */
static void retransmit_data_destroy(retransmit_data_t *this)
{
        chunk_free(&this->session_id);
        free(this);
}

/**
 * Creates a new retransmission data object
 */
static retransmit_data_t *retransmit_data_create(private_connect_manager_t *connect_manager,
                chunk_t session_id, u_int32_t mid)
{
        retransmit_data_t *this = malloc_thing(retransmit_data_t);
        
        this->connect_manager = connect_manager;
        this->session_id = session_id;
        this->mid = mid;

        return this;
}

typedef struct initiate_data_t initiate_data_t;

/**
 * Data required by the initiate mediated
 */
struct initiate_data_t {
        /** checklist */
        check_list_t *checklist;
        
        /** waiting mediated connections */
        initiated_t *initiated;
};

/**
 * Destroys a initiate data object
 */
static void initiate_data_destroy(initiate_data_t *this)
{
        check_list_destroy(this->checklist);
        initiated_destroy(this->initiated);
        free(this);
}

/**
 * Creates a new initiate data object
 */
static initiate_data_t *initiate_data_create(check_list_t *checklist, initiated_t *initiated)
{
        initiate_data_t *this = malloc_thing(initiate_data_t);
        
        this->checklist = checklist;
        this->initiated = initiated;

        return this;
}

/**
 * Find an initiated connection by the peers' ids
 */
static status_t get_initiated_by_ids(private_connect_manager_t *this,
                identification_t *id, identification_t *peer_id, initiated_t **initiated)
{
        iterator_t *iterator;
        initiated_t *current;
        status_t status = NOT_FOUND;
        
        iterator = this->initiated->create_iterator(this->initiated, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (id->equals(id, current->id) && peer_id->equals(peer_id, current->peer_id))
                {
                        if (initiated)
                        {
                                *initiated = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);

        return status;
}

/**
 * Removes data about initiated connections
 */
static void remove_initiated(private_connect_manager_t *this, initiated_t *initiated)
{
        iterator_t *iterator;
        initiated_t *current;
        
        iterator = this->initiated->create_iterator(this->initiated, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (current == initiated)
                {
                        iterator->remove(iterator);
                        break;
                }
        }
        iterator->destroy(iterator);
}

/**
 * Finds a waiting sa
 */
static status_t get_waiting_sa(initiated_t *initiated, ike_sa_id_t *ike_sa_id, waiting_sa_t **waiting_sa)
{
        iterator_t *iterator;
        waiting_sa_t *current;
        status_t status = NOT_FOUND;
        
        iterator = initiated->mediated->create_iterator(initiated->mediated, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (ike_sa_id->equals(ike_sa_id, current->ike_sa_id))
                {
                        if (waiting_sa)
                        {
                                *waiting_sa = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);

        return status;
}

/**
 * Find the checklist with a specific session ID
 */
static status_t get_checklist_by_id(private_connect_manager_t *this,
                chunk_t session_id, check_list_t **check_list)
{
        iterator_t *iterator;
        check_list_t *current;
        status_t status = NOT_FOUND;
        
        iterator = this->checklists->create_iterator(this->checklists, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (chunk_equals(session_id, current->session_id))
                {
                        if (check_list)
                        {
                                *check_list = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);

        return status;
}

/**
 * Removes a checklist
 */
static void remove_checklist(private_connect_manager_t *this, check_list_t *checklist)
{
        iterator_t *iterator;
        check_list_t *current;
        
        iterator = this->checklists->create_iterator(this->checklists, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (current == checklist)
                {
                        iterator->remove(iterator);
                        break;
                }
        }
        iterator->destroy(iterator);
}

/**
 * Checks if a list of endpoint_notify_t contains a certain host_t
 */
static status_t endpoints_contain(linked_list_t *endpoints, host_t *host, endpoint_notify_t **endpoint)
{
        iterator_t *iterator;
        endpoint_notify_t *current;
        status_t status = NOT_FOUND;
        
        iterator = endpoints->create_iterator(endpoints, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (host->equals(host, current->get_host(current)))
                {
                        if (endpoint)
                        {
                                *endpoint = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);
        
        return status;
}

/**
 * Updates the state of the whole checklist
 */
static void update_checklist_state(check_list_t *checklist)
{
        iterator_t *iterator;
        endpoint_pair_t *current;
        bool in_progress = FALSE, succeeded = FALSE;

        iterator = checklist->pairs->create_iterator(checklist->pairs, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                switch(current->state)
                {
                        case CHECK_WAITING:
                                /* at least one is still waiting -> checklist remains
                                 * in waiting state */
                                iterator->destroy(iterator);
                                return;
                        case CHECK_IN_PROGRESS:
                                in_progress = TRUE;
                                break;
                        case CHECK_SUCCEEDED:
                                succeeded = TRUE;
                                break;
                        default:
                                break;
                }
        }
        iterator->destroy(iterator);
        
        if (in_progress)
        {
                checklist->state = CHECK_IN_PROGRESS;
        }
        else if (succeeded)
        {
                checklist->state = CHECK_SUCCEEDED;
        }
        else
        {
                checklist->state = CHECK_FAILED;
        }
}

/**
 * Inserts an endpoint pair into the list of pairs ordered by priority (high to low)
 */
static void insert_pair_by_priority(linked_list_t *pairs, endpoint_pair_t *pair)
{
        iterator_t *iterator;
        endpoint_pair_t *current;
        bool inserted = FALSE;
        
        iterator = pairs->create_iterator(pairs, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (current->priority < pair->priority)
                {
                        iterator->insert_before(iterator, pair);
                        inserted = TRUE;
                        break;
                }
        }
        iterator->destroy(iterator);
        
        if (!inserted)
        {
                pairs->insert_last(pairs, pair);
        }
}

/**
 * Searches a list of endpoint_pair_t for a pair with specific host_ts
 */
static status_t get_pair_by_hosts(linked_list_t *pairs, host_t *local, host_t *remote, endpoint_pair_t **pair)
{
        iterator_t *iterator;
        endpoint_pair_t *current;
        status_t status = NOT_FOUND;
        
        iterator = pairs->create_iterator(pairs, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (local->equals(local, current->local) &&
                                remote->equals(remote, current->remote))
                {
                        if (pair)
                        {
                                *pair = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);
        
        return status;
}

/**
 * Searches for a pair with a specific id
 */
static status_t get_pair_by_id(check_list_t *checklist, u_int32_t id, endpoint_pair_t **pair)
{
        iterator_t *iterator;
        endpoint_pair_t *current;
        status_t status = NOT_FOUND;
        
        iterator = checklist->pairs->create_iterator(checklist->pairs, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (current->id == id)
                {
                        if (pair)
                        {
                                *pair = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);
        
        return status;
}

/**
 * Returns the best pair of state CHECK_SUCCEEDED from a checklist. 
 */
static status_t get_best_valid_pair(check_list_t *checklist, endpoint_pair_t **pair)
{
        iterator_t *iterator;
        endpoint_pair_t *current;
        status_t status = NOT_FOUND;
        
        iterator = checklist->pairs->create_iterator(checklist->pairs, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                if (current->state == CHECK_SUCCEEDED)
                {
                        if (pair)
                        {
                                *pair = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);
        
        return status;
}

/**
 * Returns and removes the first triggered pair in state CHECK_WAITING. 
 */
static status_t get_triggered_pair(check_list_t *checklist, endpoint_pair_t **pair)
{
        iterator_t *iterator;
        endpoint_pair_t *current;
        status_t status = NOT_FOUND;
        
        iterator = checklist->triggered->create_iterator(checklist->triggered, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                iterator->remove(iterator);
                
                if (current->state == CHECK_WAITING)
                {
                        if (pair)
                        {
                                *pair = current;
                        }
                        status = SUCCESS;
                        break;
                }
        }
        iterator->destroy(iterator);
        
        return status;
}

/**
 * Prunes identical pairs with lower priority from the list
 * Note: this function also numbers the remaining pairs serially
 */
static void prune_pairs(linked_list_t *pairs)
{
        iterator_t *iterator, *search;
        endpoint_pair_t *current, *other;
        u_int32_t id = 0;
        
        iterator = pairs->create_iterator(pairs, TRUE);
        search = pairs->create_iterator(pairs, TRUE);
        while (iterator->iterate(iterator, (void**)&current))
        {
                current->id = ++id;
                
                while (search->iterate(search, (void**)&other))
                {
                        if (current == other)
                        {
                                continue;
                        }
                        
                        if (current->local->equals(current->local, other->local) &&
                                        current->remote->equals(current->remote, other->remote))
                        {
                                /* since the list of pairs is sorted by priority in descending
                                 * order, and we iterate the list from the beginning, we are
                                 * sure that the priority of 'other' is lower than that of
                                 * 'current', remove it */
                                DBG1(DBG_IKE, "pruning endpoint pair %H - %H with priority %d",
                                                other->local, other->remote, other->priority);
                                search->remove(search);
                                endpoint_pair_destroy(other);
                        }
                }
                search->reset(search);
        }
        search->destroy(search);
        iterator->destroy(iterator);
}

/**
 * Builds a list of endpoint pairs
 */
static void build_pairs(check_list_t *checklist)
{
        iterator_t *iterator_i, *iterator_r;
        endpoint_notify_t *initiator, *responder;
        
        iterator_i = checklist->initiator.endpoints->create_iterator(checklist->initiator.endpoints, TRUE);
        while (iterator_i->iterate(iterator_i, (void**)&initiator))
        {
                iterator_r = checklist->responder.endpoints->create_iterator(checklist->responder.endpoints, TRUE);
                while (iterator_r->iterate(iterator_r, (void**)&responder))
                {
                        if (initiator->get_family(initiator) != responder->get_family(responder))
                        {
                                continue;
                        }
                        
                        insert_pair_by_priority(checklist->pairs,
                                        endpoint_pair_create(initiator, responder, checklist->is_initiator));
                }
                iterator_r->destroy(iterator_r);
        }
        iterator_i->destroy(iterator_i);

        prune_pairs(checklist->pairs);
}

/**
 * Processes the payloads of a connectivity check and returns the extracted data
 */
static status_t process_payloads(message_t *message, check_t *check)
{
        iterator_t *iterator;
        payload_t *payload;

        iterator = message->get_payload_iterator(message);
        while (iterator->iterate(iterator, (void**)&payload))
        {
                if (payload->get_type(payload) != NOTIFY)
                {
                        DBG1(DBG_IKE, "ignoring payload of type '%N' while processing "
                                        "connectivity check", payload_type_names, payload->get_type(payload));
                        continue;
                }
                
                notify_payload_t *notify = (notify_payload_t*)payload;
                
                switch (notify->get_notify_type(notify))
                {
                        case P2P_ENDPOINT:
                        {
                                if (check->endpoint)
                                {
                                        DBG1(DBG_IKE, "connectivity check contains multiple P2P_ENDPOINT notifies");
                                        break;
                                }
                                
                                endpoint_notify_t *endpoint = endpoint_notify_create_from_payload(notify);
                                if (!endpoint)
                                {
                                        DBG1(DBG_IKE, "received invalid P2P_ENDPOINT notify");
                                        break;
                                }
                                check->endpoint = endpoint;
                                check->endpoint_raw = chunk_clone(notify->get_notification_data(notify));
                                DBG2(DBG_IKE, "received P2P_ENDPOINT notify");
                                break;
                        }
                        case P2P_SESSIONID:
                        {
                                if (check->session_id.ptr)
                                {
                                        DBG1(DBG_IKE, "connectivity check contains multiple P2P_SESSIONID notifies");
                                        break;
                                }
                                check->session_id = chunk_clone(notify->get_notification_data(notify));
                                DBG3(DBG_IKE, "received p2p_sessionid %B", &check->session_id);
                                break;
                        }
                        case COOKIE:
                        {
                                if (check->cookie.ptr)
                                {
                                        DBG1(DBG_IKE, "connectivity check contains multiple COOKIE notifies");
                                        break;
                                }
                                check->cookie = chunk_clone(notify->get_notification_data(notify));
                                DBG3(DBG_IKE, "received cookie %B", &check->cookie);
                                break;
                        }
                        default:
                                break;
                }
        }
        iterator->destroy(iterator);
        
        if (!check->session_id.ptr || !check->endpoint || !check->cookie.ptr)
        {
                DBG1(DBG_IKE, "at least one payload was missing from the connectivity check");
                return FAILED;
        }
        
        return SUCCESS;
}

/**
 * Builds the signature for a connectivity check
 */
static chunk_t build_signature(private_connect_manager_t *this, 
                check_list_t *checklist, check_t *check, bool outbound)
{
        chunk_t mid_chunk, key_chunk, sig_chunk;
        chunk_t sig_hash;
        
        mid_chunk = chunk_from_thing(check->mid);
        
        key_chunk = (checklist->is_initiator && outbound) || (!checklist->is_initiator && !outbound)
                                        ? checklist->initiator.key : checklist->responder.key;
        
        /* signature = SHA1( MID | P2P_SESSIONID | P2P_ENDPOINT | P2P_SESSIONKEY ) */
        sig_chunk = chunk_cat("cccc", mid_chunk, check->session_id, check->endpoint_raw, key_chunk);
        this->hasher->allocate_hash(this->hasher, sig_chunk, &sig_hash);
        DBG3(DBG_IKE, "sig_chunk %B", &sig_chunk);
        DBG3(DBG_IKE, "sig_hash %B", &sig_hash);
        
        chunk_free(&sig_chunk);
        return sig_hash;
}

static void queue_retransmission(private_connect_manager_t *this, chunk_t session_id, u_int32_t mid);
static void schedule_checks(private_connect_manager_t *this, check_list_t *checklist, u_int32_t time);
static void finish_checks(private_connect_manager_t *this, check_list_t *checklist);

/**
 * This function is triggered for each sent check after a specific timeout
 */
static job_requeue_t retransmit(retransmit_data_t *data)
{
        private_connect_manager_t *this = data->connect_manager;
        
        pthread_mutex_lock(&(this->mutex));

        check_list_t *checklist;
        if (get_checklist_by_id(this, data->session_id, &checklist) != SUCCESS)
        {
                DBG1(DBG_IKE, "checklist with id '%B' not found, can't retransmit connectivity check",
                                &data->session_id);
                pthread_mutex_unlock(&(this->mutex));
                return JOB_REQUEUE_NONE;
        }
        
        endpoint_pair_t *pair;
        if (get_pair_by_id(checklist, data->mid, &pair) != SUCCESS)
        {
                DBG1(DBG_IKE, "pair with id '%d' not found, can't retransmit connectivity check",
                                data->mid);
                goto retransmit_end;
        }
        
        if (pair->state != CHECK_IN_PROGRESS)
        {
                DBG2(DBG_IKE, "pair with id '%d' is in wrong state [%d], don't retransmit the connectivity check",
                                data->mid, pair->state);
                goto retransmit_end;
        }
        
        if (++pair->retransmitted >= P2P_MAX_RETRANS)
        {
                DBG2(DBG_IKE, "pair with id '%d' failed after %d tries",
                                data->mid, pair->retransmitted);
                pair->state = CHECK_FAILED;
                goto retransmit_end;
        }
        
        charon->sender->send(charon->sender, pair->packet->clone(pair->packet));
        
        queue_retransmission(this, checklist->session_id, pair->id);

retransmit_end:
        update_checklist_state(checklist);
        
        switch(checklist->state)
        {
                case CHECK_SUCCEEDED:
                case CHECK_FAILED:
                        finish_checks(this, checklist);
                        break;
                default:
                        break;
        }
        
        pthread_mutex_unlock(&(this->mutex));
        
        /* we reschedule it manually */
        return JOB_REQUEUE_NONE;
}

/**
 * Queues a retransmission job
 */
static void queue_retransmission(private_connect_manager_t *this, chunk_t session_id, u_int32_t mid)
{
        retransmit_data_t *data = retransmit_data_create(this, chunk_clone(session_id), mid);
        job_t *job = (job_t*)callback_job_create((callback_job_cb_t)retransmit, data, (callback_job_cleanup_t)retransmit_data_destroy, NULL);
        charon->scheduler->schedule_job(charon->scheduler, (job_t*)job, P2P_RTO_MIN);
}

/**
 * Sends a check
 */
static void send_check(private_connect_manager_t *this, check_list_t *checklist,
                check_t *check, endpoint_pair_t *pair, bool request)
{
        message_t *message = message_create();
        message->set_message_id(message, check->mid);
        message->set_exchange_type(message, INFORMATIONAL);
        message->set_request(message, request);
        message->set_destination(message, check->dst->clone(check->dst));
        message->set_source(message, check->src->clone(check->src));
        
        message->set_ike_sa_id(message, ike_sa_id_create(0, 0, request));

        message->add_notify(message, FALSE, P2P_SESSIONID, check->session_id);
        
        notify_payload_t *endpoint = check->endpoint->build_notify(check->endpoint);
        check->endpoint_raw = chunk_clone(endpoint->get_notification_data(endpoint));
        message->add_payload(message, (payload_t*)endpoint);
        
        check->cookie = build_signature(this, checklist, check, TRUE);
        message->add_notify(message, FALSE, COOKIE, check->cookie);
        
        packet_t *packet;
        if (message->generate(message, NULL, NULL, &packet) == SUCCESS)
        {
                charon->sender->send(charon->sender, packet->clone(packet));
                
                if (request)
                {
                        DESTROY_IF(pair->packet);
                        pair->packet = packet;
                        queue_retransmission(this, checklist->session_id, pair->id);
                }
                else
                {
                        packet->destroy(packet);
                }
        }
}

/**
 * Queues a triggered check
 */
static void queue_triggered_check(check_list_t *checklist, endpoint_pair_t *pair)
{
        pair->state = CHECK_WAITING;
        checklist->triggered->insert_last(checklist->triggered, pair);
}

/**
 * This function is triggered for each checklist at a specific interval
 */
static job_requeue_t sender(sender_data_t *data)
{
        private_connect_manager_t *this = data->connect_manager;

        pthread_mutex_lock(&(this->mutex));

        check_list_t *checklist;
        if (get_checklist_by_id(this, data->session_id, &checklist) != SUCCESS)
        {
                DBG1(DBG_IKE, "checklist with id '%B' not found, can't send connectivity check",
                                &data->session_id);
                pthread_mutex_unlock(&(this->mutex));
                return JOB_REQUEUE_NONE;
        }
        
        endpoint_pair_t *pair;
        if (get_triggered_pair(checklist, &pair) != SUCCESS)
        {
                DBG1(DBG_IKE, "no triggered check queued, sending an ordinary check");
                
                iterator_t *iterator;
                bool found_one = FALSE;
        
                iterator = checklist->pairs->create_iterator(checklist->pairs, TRUE);
                while (iterator->iterate(iterator, (void**)&pair))
                {
                        if (pair->state == CHECK_WAITING)
                        {
                                found_one = TRUE;
                                break;
                        }
                }
                iterator->destroy(iterator);
        
                if (!found_one)
                {
                        pthread_mutex_unlock(&(this->mutex));
                        DBG1(DBG_IKE, "no pairs in waiting state, aborting");
                        return JOB_REQUEUE_NONE;
                }
        }
        else
        {
                DBG1(DBG_IKE, "triggered check found");
        }

        check_t *check = check_create();
        check->mid = pair->id;
        check->src = pair->local->clone(pair->local);
        check->dst = pair->remote->clone(pair->remote);
        check->session_id = chunk_clone(checklist->session_id);
        check->endpoint = endpoint_notify_create();
        
        pair->state = CHECK_IN_PROGRESS;
        
        send_check(this, checklist, check, pair, TRUE);
        
        check_destroy(check);
        
        /* schedule this job again */
        u_int32_t N = this->checklists->get_count(this->checklists);
        schedule_checks(this, checklist, P2P_INTERVAL * N);
        
        pthread_mutex_unlock(&(this->mutex));
        
        /* we reschedule it manually */
        return JOB_REQUEUE_NONE;
}

/**
 * Schedules checks for a checklist (time in ms)
 */
static void schedule_checks(private_connect_manager_t *this, check_list_t *checklist, u_int32_t time)
{
        chunk_t session_id = chunk_clone(checklist->session_id);
        sender_data_t *data = sender_data_create(this, session_id);
        job_t *job = (job_t*)callback_job_create((callback_job_cb_t)sender, data, (callback_job_cleanup_t)sender_data_destroy, NULL);
        charon->scheduler->schedule_job(charon->scheduler, job, time);
}

/**
 * Initiates waiting mediated connections
 */
static job_requeue_t initiate_mediated(initiate_data_t *data)
{
        check_list_t *checklist = data->checklist;
        initiated_t *initiated = data->initiated;
        
        endpoint_pair_t *pair;
        if (get_best_valid_pair(checklist, &pair) == SUCCESS)
        {
                waiting_sa_t *waiting_sa;
                iterator_t *iterator = initiated->mediated->create_iterator(initiated->mediated, TRUE);
                while (iterator->iterate(iterator, (void**)&waiting_sa))
                {
                        ike_sa_t *sa = charon->ike_sa_manager->checkout(charon->ike_sa_manager, waiting_sa->ike_sa_id);
                        if (sa->initiate_mediated(sa, pair->local, pair->remote, waiting_sa->childs) != SUCCESS)
                        {
                                SIG(IKE_UP_FAILED, "establishing the mediated connection failed");
                                charon->ike_sa_manager->checkin_and_destroy(charon->ike_sa_manager, sa);
                        }
                        charon->ike_sa_manager->checkin(charon->ike_sa_manager, sa);
                }
                iterator->destroy(iterator);
        }
        else
        {
                /* this should (can?) not happen */
        }
        
        return JOB_REQUEUE_NONE;
}

/**
 * Finishes checks for a checklist
 */
static void finish_checks(private_connect_manager_t *this, check_list_t *checklist)
{
        if (checklist->is_initiator)
        {
                initiated_t *initiated;
                if (get_initiated_by_ids(this, checklist->initiator.id,
                                checklist->responder.id, &initiated) == SUCCESS)
                {
                        remove_checklist(this, checklist);
                        remove_initiated(this, initiated);
                        
                        initiate_data_t *data = initiate_data_create(checklist, initiated);
                        job_t *job = (job_t*)callback_job_create((callback_job_cb_t)initiate_mediated, data, (callback_job_cleanup_t)initiate_data_destroy, NULL);
                        charon->processor->queue_job(charon->processor, job);
                        return;
                }
                else
                {
                        DBG1(DBG_IKE, "there is no mediated connection waiting between '%D' "
                                        "and '%D'", checklist->initiator.id, checklist->responder.id);
                }
        }
        
        /* remove_checklist(this, checklist);
         * check_list_destroy(checklist);
         * FIXME: we should do this ^^^ after a specific timeout on the 
         * responder side */
}

/**
 * Process the response to one of our requests
 */
static void process_response(private_connect_manager_t *this, check_t *check,
                check_list_t *checklist)
{
        endpoint_pair_t *pair;
        if (get_pair_by_id(checklist, check->mid, &pair) == SUCCESS)
        {
                if (pair->local->equals(pair->local, check->dst) &&
                                pair->remote->equals(pair->remote, check->src))
                {
                        DBG1(DBG_IKE, "endpoint pair '%d' is valid: '%#H' - '%#H'", pair->id,
                                        pair->local, pair->remote);
                        pair->state = CHECK_SUCCEEDED;
                }
                
                linked_list_t *local_endpoints = checklist->is_initiator ?
                        checklist->initiator.endpoints : checklist->responder.endpoints;
                
                endpoint_notify_t *local_endpoint;
                if (endpoints_contain(local_endpoints,
                                check->endpoint->get_host(check->endpoint), &local_endpoint) != SUCCESS)
                {
                        local_endpoint = endpoint_notify_create_from_host(PEER_REFLEXIVE,
                                        check->endpoint->get_host(check->endpoint), pair->local);
                        local_endpoint->set_priority(local_endpoint, check->endpoint->get_priority(check->endpoint));
                        local_endpoints->insert_last(local_endpoints, local_endpoint);
                }
                
                update_checklist_state(checklist);
                
                switch(checklist->state)
                {
                        case CHECK_SUCCEEDED:
                        case CHECK_FAILED:
                                finish_checks(this, checklist);
                                break;
                        default:
                                break;
                }
        }
        else
        {
                DBG1(DBG_IKE, "pair with id '%d' not found", check->mid);
        }
}

static void process_request(private_connect_manager_t *this, check_t *check,
                check_list_t *checklist)
{
        linked_list_t *remote_endpoints = checklist->is_initiator ?
                                checklist->responder.endpoints : checklist->initiator.endpoints;
                
        endpoint_notify_t *peer_reflexive, *remote_endpoint;
        peer_reflexive = endpoint_notify_create_from_host(PEER_REFLEXIVE, check->src, NULL);
        peer_reflexive->set_priority(peer_reflexive, check->endpoint->get_priority(check->endpoint));
                
        if (endpoints_contain(remote_endpoints, check->src, &remote_endpoint) != SUCCESS)
        {
                remote_endpoint = peer_reflexive->clone(peer_reflexive);
                remote_endpoints->insert_last(remote_endpoints, remote_endpoint);
        }
        
        endpoint_pair_t *pair;
        if (get_pair_by_hosts(checklist->pairs, check->dst, check->src, &pair) == SUCCESS)
        {
                switch(pair->state)
                {
                        case CHECK_IN_PROGRESS:
                                /* prevent retransmissions */
                                pair->retransmitted = P2P_MAX_RETRANS; 
                                /* FIXME: we should wait to the next rto to send the triggered check
                                 * fall-through */
                        case CHECK_WAITING:
                        case CHECK_FAILED:
                                queue_triggered_check(checklist, pair);
                                break;
                        case CHECK_SUCCEEDED:
                        default:
                                break;
                }
        }
        else
        {
                endpoint_notify_t *local_endpoint = endpoint_notify_create_from_host(HOST, check->dst, NULL);
                
                endpoint_notify_t *initiator = checklist->is_initiator ? local_endpoint : remote_endpoint;
                endpoint_notify_t *responder = checklist->is_initiator ? remote_endpoint : local_endpoint;
                
                pair = endpoint_pair_create(initiator, responder, checklist->is_initiator);
                pair->id = checklist->pairs->get_count(checklist->pairs) + 1;
                
                insert_pair_by_priority(checklist->pairs, pair);
                
                queue_triggered_check(checklist, pair);
                
                local_endpoint->destroy(local_endpoint);
        }
        
        
        check_t *response = check_create();
        
        response->mid = check->mid;
        response->src = check->dst->clone(check->dst);
        response->dst = check->src->clone(check->src);
        response->session_id = chunk_clone(check->session_id);
        response->endpoint = peer_reflexive;
        
        send_check(this, checklist, response, pair, FALSE);
        
        check_destroy(response);
}

/**
 * Implementation of connect_manager_t.process_check.
 */
static void process_check(private_connect_manager_t *this, message_t *message)
{
        if (message->parse_body(message, NULL, NULL) != SUCCESS)
        {
                DBG1(DBG_IKE, "%N %s with message ID %d processing failed",
                         exchange_type_names, message->get_exchange_type(message),
                         message->get_request(message) ? "request" : "response",
                         message->get_message_id(message));
                return;
        }
        
        check_t *check = check_create();
        check->mid = message->get_message_id(message);
        check->src = message->get_source(message);
        check->dst = message->get_destination(message);
        
        if (process_payloads(message, check) != SUCCESS)
        {
                DBG1(DBG_IKE, "invalid connectivity check %s received",
                                message->get_request(message) ? "request" : "response");
                check_destroy(check);
                return;
        }
        
        pthread_mutex_lock(&(this->mutex));
        
        check_list_t *checklist;
        if (get_checklist_by_id(this, check->session_id, &checklist) != SUCCESS)
        {
                DBG1(DBG_IKE, "checklist with id '%B' not found",
                                &check->session_id);
                check_destroy(check);
                pthread_mutex_unlock(&(this->mutex));
                return;
        }
        
        chunk_t sig = build_signature(this, checklist, check, FALSE); 
        if (!chunk_equals(sig, check->cookie))
        {
                DBG1(DBG_IKE, "connectivity check verification failed");
                check_destroy(check);
                chunk_free(&sig);
                pthread_mutex_unlock(&(this->mutex));
                return;
        }
        chunk_free(&sig);
        
        if (message->get_request(message))
        {
                process_request(this, check, checklist);
        }
        else
        {
                process_response(this, check, checklist);
        }
        
        pthread_mutex_unlock(&(this->mutex));
        
        check_destroy(check);
}

/**
 * Implementation of connect_manager_t.check_and_register.
 */
static bool check_and_register(private_connect_manager_t *this,
                        identification_t *id, identification_t *peer_id,
                        ike_sa_id_t *mediated_sa, child_cfg_t *child)
{
        initiated_t *initiated;
        bool already_there = TRUE;

        pthread_mutex_lock(&(this->mutex));

        if (get_initiated_by_ids(this, id, peer_id, &initiated) != SUCCESS)
        {
                DBG2(DBG_IKE, "registered waiting mediated connection with '%D'", peer_id);
                initiated = initiated_create(id, peer_id);
                this->initiated->insert_last(this->initiated, initiated);
                already_there = FALSE;
        }
        
        waiting_sa_t *waiting_sa;
        if (get_waiting_sa(initiated, mediated_sa, &waiting_sa) != SUCCESS)
        {
                waiting_sa = waiting_sa_create(mediated_sa);
                initiated->mediated->insert_last(initiated->mediated, waiting_sa);
        }

        child->get_ref(child);
        waiting_sa->childs->insert_last(waiting_sa->childs, child);

        pthread_mutex_unlock(&(this->mutex));

        return already_there;
}

/**
 * Implementation of connect_manager_t.check_and_initiate.
 */
static void check_and_initiate(private_connect_manager_t *this, ike_sa_id_t *mediation_sa,
                identification_t *id, identification_t *peer_id)
{
        initiated_t *initiated;

        pthread_mutex_lock(&(this->mutex));

        if (get_initiated_by_ids(this, id, peer_id, &initiated) != SUCCESS)
        {
                DBG2(DBG_IKE, "no waiting mediated connections with '%D'", peer_id);
                pthread_mutex_unlock(&(this->mutex));
                return;
        }
        
        waiting_sa_t *waiting_sa;
        iterator_t *iterator = initiated->mediated->create_iterator(initiated->mediated, TRUE);
        while (iterator->iterate(iterator, (void**)&waiting_sa))
        {
                job_t *job = (job_t*)reinitiate_mediation_job_create(mediation_sa,
                                waiting_sa->ike_sa_id);
                charon->processor->queue_job(charon->processor, job);
        }

        pthread_mutex_unlock(&(this->mutex));
}

/**
 * Implementation of connect_manager_t.set_initiator_data.
 */
static status_t set_initiator_data(private_connect_manager_t *this,
                identification_t *initiator, identification_t *responder,
                chunk_t session_id, chunk_t key, linked_list_t *endpoints, bool is_initiator)
{
        check_list_t *checklist;
        
        pthread_mutex_lock(&(this->mutex));     
        
        if (get_checklist_by_id(this, session_id, NULL) == SUCCESS)
        {
                DBG1(DBG_IKE, "checklist with id '%B' already exists, aborting",
                                &session_id);
                pthread_mutex_unlock(&(this->mutex));
                return FAILED;
        }
        
        checklist = check_list_create(initiator, responder, session_id, key, endpoints, is_initiator);
        this->checklists->insert_last(this->checklists, checklist);
        
        pthread_mutex_unlock(&(this->mutex));
        
        return SUCCESS;
}

/**
 * Implementation of connect_manager_t.set_responder_data.
 */
static status_t set_responder_data(private_connect_manager_t *this,
                chunk_t session_id, chunk_t key, linked_list_t *endpoints)
{
        check_list_t *checklist;

        pthread_mutex_lock(&(this->mutex));
        
        if (get_checklist_by_id(this, session_id, &checklist) != SUCCESS)
        {
                DBG1(DBG_IKE, "checklist with id '%B' not found",
                                &session_id);
                pthread_mutex_unlock(&(this->mutex));
                return NOT_FOUND;
        }
        
        checklist->responder.key = chunk_clone(key);
        checklist->responder.endpoints = endpoints->clone_offset(endpoints, offsetof(endpoint_notify_t, clone));
        checklist->state = CHECK_WAITING;
        
        build_pairs(checklist);
        
        /* send the first check immediately */
        schedule_checks(this, checklist, 0);
        
        pthread_mutex_unlock(&(this->mutex));
        
        return SUCCESS;
}

/**
 * Implementation of connect_manager_t.destroy.
 */
static void destroy(private_connect_manager_t *this)
{
        pthread_mutex_lock(&(this->mutex));
        
        this->hasher->destroy(this->hasher);
        this->checklists->destroy_function(this->checklists, (void*)check_list_destroy);
        this->initiated->destroy_function(this->initiated, (void*)initiated_destroy);
        
        pthread_mutex_unlock(&(this->mutex));   
        pthread_mutex_destroy(&(this->mutex));
        free(this);
}

/*
 * Described in header.
 */
connect_manager_t *connect_manager_create()
{
        private_connect_manager_t *this = malloc_thing(private_connect_manager_t);

        this->public.destroy = (void(*)(connect_manager_t*))destroy;
        this->public.check_and_register = (bool(*)(connect_manager_t*,identification_t*,identification_t*,ike_sa_id_t*,child_cfg_t*))check_and_register;
        this->public.check_and_initiate = (void(*)(connect_manager_t*,ike_sa_id_t*,identification_t*,identification_t*))check_and_initiate;
        this->public.set_initiator_data = (status_t(*)(connect_manager_t*,identification_t*,identification_t*,chunk_t,chunk_t,linked_list_t*,bool))set_initiator_data;
        this->public.set_responder_data = (status_t(*)(connect_manager_t*,chunk_t,chunk_t,linked_list_t*))set_responder_data;
        this->public.process_check = (void(*)(connect_manager_t*,message_t*))process_check;
        
        this->hasher = hasher_create(HASH_SHA1);
        this->checklists = linked_list_create();
        this->initiated = linked_list_create();
        
        pthread_mutex_init(&(this->mutex), NULL);
        
        return (connect_manager_t*)this;
}