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/*
     This file is part of GNUnet.
     (C) 2001 - 2011 Christian Grothoff (and other contributing authors)

     GNUnet 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 3, or (at your
     option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file mesh/gnunet-service-mesh.c
 * @brief GNUnet MESH service
 * @author Bartlomiej Polot
 *
 * STRUCTURE:
 * - DATA STRUCTURES
 * - GLOBAL VARIABLES
 * - MESH NETWORK HANDLES
 * - MESH LOCAL HANDLES
 * - MAIN FUNCTIONS (main & run)
 * 
 * TODO:
 * - soft stateing (keep-alive (CHANGE?) / timeout / disconnect) -- not a message issue
 * - error reporting (CREATE/CHANGE/ADD/DEL?) -- new message!
 * - partial disconnect reporting -- same as error reporting?
 * - add vs create? change vs. keep-alive? same msg or different ones? -- thinking...
 * - speed requirement specification (change?) in mesh API -- API call
 */

#include "platform.h"
#include "gnunet_common.h"
#include "gnunet_util_lib.h"
#include "gnunet_peer_lib.h"
#include "gnunet_core_service.h"
#include "gnunet_protocols.h"

#include "mesh.h"
#include "mesh_protocol.h"
#include "gnunet_dht_service.h"


/******************************************************************************/
/************************      DATA STRUCTURES     ****************************/
/******************************************************************************/

/**
 * All the states a peer participating in a tunnel can be in.
 */
enum PeerState
{
    /**
     * Path to the peer not known yet
     */
    MESH_PEER_SEARCHING,

    /**
     * Request sent, not yet answered.
     */
    MESH_PEER_WAITING,

    /**
     * Peer connected and ready to accept data
     */
    MESH_PEER_READY,

    /**
     * Peer connected previosly but not responding
     */
    MESH_PEER_RECONNECTING
};

/**
 * Struct containing all information regarding a given peer
 */
struct PeerInfo
{
    /**
     * Double linked list
     */
    struct PeerInfo             *next;
    struct PeerInfo             *prev;

    /**
     * ID of the peer
     */
    GNUNET_PEER_Id              id;

    /**
     * Tunnel this peer belongs to
     */
    struct MESH_tunnel          *t;

    /**
     * Is the peer reachable? Is the peer even connected?
     */
    enum PeerState              state;

    /**
     * When to try to establish contact again?
     */
    struct GNUNET_TIME_Absolute next_reconnect_attempt;

    /**
     * Who to send the data to --- FIXME what about multiple (alternate) paths?
     */
    GNUNET_PEER_Id              first_hop;

    /**
     * Max data rate to this peer
     */
    uint32_t                    max_speed;

    /**
     * Handle to stop the DHT search for a path to this peer
     */
    struct GNUNET_DHT_GetHandle        *dhtget;
};


typedef uint32_t MESH_PathID;


/**
 * Information regarding a path
 */
struct Path
{
    /**
     * Double linked list
     */
    struct Path                 *next;
    struct Path                 *prev;

    /**
     * Id of the path, in case it's needed
     */
    MESH_PathID                 id;

    /**
     * Whether the path is serving traffic in a tunnel or is a backup
     */
    int                         in_use;

    /**
     * List of all the peers that form the path from origin to target
     */
    GNUNET_PEER_Id              *peers;
    int                         length;
};

/**
 * Data scheduled to transmit (to local client or remote peer)
 */
struct MESH_queue
{
    /**
     * Double linked list
     */
    struct MESH_queue          *next;
    struct MESH_queue          *prev;

    /**
     * Size of the message to transmit
     */
    unsigned int                size;

    /**
     * How old is the data?
     */
    struct GNUNET_TIME_Absolute timestamp;

    /**
     * Data itself
     */
    struct GNUNET_MessageHeader *data;
};


struct Client; /* FWD declaration */
/**
 * Struct containing all information regarding a tunnel
 * For an intermediate node the improtant info used will be:
 * - OID        \ To identify
 * - TID        / the tunnel
 * - paths[0]   | To know where to send it next
 * - metainfo: ready, speeds, accounting
 * For an end node more fields will be needed (client-handling)
 */
struct MESH_tunnel
{

    /**
     * Double linked list
     */
    struct MESH_tunnel          *next;
    struct MESH_tunnel          *prev;

    /**
     * Origin ID: Node that created the tunnel
     */
    GNUNET_PEER_Id              oid;

    /**
     * Tunnel number (unique for a given oid)
     */
    MESH_TunnelID               tid;

    /**
     * Minimal speed for this tunnel in kb/s
     */
    uint32_t                    speed_min;

    /**
     * Maximal speed for this tunnel in kb/s
     */
    uint32_t                    speed_max;

    /**
     * Last time the tunnel was used
     */
    struct GNUNET_TIME_Absolute timestamp;

    /**
     * Peers in the tunnel, for future optimizations
     */
    struct PeerInfo             *peers_head;
    struct PeerInfo             *peers_tail;

    /**
     * Number of peers that are connected and potentially ready to receive data
     */
    unsigned int                peers_ready;

    /**
     * Number of peers that have been added to the tunnel
     */
    unsigned int                peers_total;

    /**
     * Paths (used and backup)
     */
    struct Path                 *paths_head;
    struct Path                 *paths_tail;

    /**
     * If this tunnel was created by a local client, what's its handle?
     */
    struct Client               *client;

    /**
     * Messages ready to transmit
     */
    struct MESH_queue           *out_head;
    struct MESH_queue           *out_tail;

    /**
     * Messages received and not processed
     */
    struct MESH_queue           *in_head;
    struct MESH_queue           *in_tail;

};

/**
 * Struct containing information about a client of the service
 */
struct Client
{
    /**
     * Double linked list
     */
    struct Client               *next;
    struct Client               *prev;

    /**
     * Tunnels that belong to this client, for convenience on disconnect
     */
    struct MESH_tunnel          *tunnels_head;
    struct MESH_tunnel          *tunnels_tail;

    /**
     * Handle to communicate with the client
     */
    struct GNUNET_SERVER_Client *handle;

    /**
     * Messages that this client has declared interest in
     */
    GNUNET_MESH_ApplicationType *messages_subscribed;
    unsigned int                subscription_counter;

};

/******************************************************************************/
/***********************      GLOBAL VARIABLES     ****************************/
/******************************************************************************/

/**
 * All the clients
 */
static struct Client                    *clients_head;
static struct Client                    *clients_tail;

/**
 * Tunnels not owned by this node
 */
// static struct MESH_Tunnel               *tunnels_head;
// static struct MESH_Tunnel               *tunnels_tail;

/**
 * Handle to communicate with core
 */
static struct GNUNET_CORE_Handle        *core_handle;

/**
 * Handle to use DHT
 */
static struct GNUNET_DHT_Handle         *dht_handle;

/**
 * Local peer own ID (memory efficient handle)
 */
static GNUNET_PEER_Id                   myid;

/******************************************************************************/
/******************      GENERAL HELPER FUNCTIONS      ************************/
/******************************************************************************/

/**
 * Check if client has registered with the service and has not disconnected
 * @param client the client to check
 * @return non-NULL if client exists in the global DLL
 */
static struct Client *
retrieve_client (struct GNUNET_SERVER_Client *client) {
    struct Client       *c;
    c = clients_head; 
    while(NULL != c) {
        if(c->handle == client) return c;
        c = c->next;
    }
    return NULL;
}

/**
 * Destroy the path and free any allocated resources linked to it
 * @param t tunnel the path belongs to
 * @param p the path to destroy
 * @return GNUNET_OK on success
 */
static int
destroy_path(struct MESH_tunnel *t, struct Path *p) {
    GNUNET_PEER_decrement_rcs(p->peers, p->length);
    GNUNET_free(p->peers);
    GNUNET_CONTAINER_DLL_remove(t->paths_head, t->paths_tail, p);
    GNUNET_free(p);
    return GNUNET_OK;
}

/**
 * Destroy the peer_info and free any allocated resources linked to it
 * @param t tunnel the path belongs to
 * @param pi the peer_info to destroy
 * @return GNUNET_OK on success
 */
static int
destroy_peer_info(struct MESH_tunnel *t, struct PeerInfo *pi) {
    GNUNET_PEER_change_rc(pi->id, -1);
    GNUNET_CONTAINER_DLL_remove(t->peers_head, t->peers_tail, pi);
    GNUNET_free(pi);
    return GNUNET_OK;
}

/**
 * Destroy the tunnel and free any allocated resources linked to it
 * @param c client the tunnel belongs to
 * @param t the tunnel to destroy
 * @return GNUNET_OK on success
 */
static int
destroy_tunnel(struct Client *c, struct MESH_tunnel *t) {
    struct PeerInfo     *pi;
    struct Path         *path;

    for(pi = t->peers_head; pi != NULL; pi = t->peers_head) {
        destroy_peer_info(t, pi);
    }

    for(path = t->paths_head; path != NULL; path = t->paths_head) {
        destroy_path(t, path);
    }

    GNUNET_CONTAINER_DLL_remove(c->tunnels_head, c->tunnels_tail, t);
    GNUNET_free(t);
    return GNUNET_OK;
}

/******************************************************************************/
/********************      MESH NETWORK HANDLERS     **************************/
/******************************************************************************/

/**
 * Function called to notify a client about the socket
 * being ready to queue more data.  "buf" will be
 * NULL and "size" zero if the socket was closed for
 * writing in the meantime.
 *
 * @param cls closure
 * @param size number of bytes available in buf
 * @param buf where the callee should write the message
 * @return number of bytes written to buf
 */
static size_t
send_core_create_path_for_peer (void *cls, size_t size, void *buf) {
    size_t                              size_needed;
    struct PeerInfo                     *peer_info;
    struct GNUNET_MESH_ManipulatePath   *msg;
    struct Path                         *p;
    struct GNUNET_PeerIdentity          peer_id;
    struct GNUNET_PeerIdentity          *peer_ptr;
    int                                 i;

    if(0 == size && NULL == buf) {
        // TODO retry? cancel?
        return 0;
    }
    peer_info = (struct PeerInfo *)cls;
    peer_info->dhtget = NULL;
    p = peer_info->t->paths_head;
    while(NULL != p) {
        if(p->peers[p->length-1] == peer_info->id) {
            break;
        }
        p = p->next;
    }
    if(p == NULL) return 0; // TODO Notify ERROR Path not found

    size_needed = sizeof(struct GNUNET_MESH_ManipulatePath)
                  + p->length * sizeof(struct GNUNET_PeerIdentity);
    if(size < size_needed) {
        // TODO retry? cancel?
        return 0;
    }

    msg = (struct GNUNET_MESH_ManipulatePath *) buf;
    msg->header.size = htons(sizeof(struct GNUNET_MESH_ManipulatePath));
    msg->header.type = htons(GNUNET_MESSAGE_TYPE_MESH_PATH_CREATE);
    msg->speed_min = 0;

    peer_ptr = (struct GNUNET_PeerIdentity *) &msg[1];
    for(i = 0; i < p->length; i++) {
        GNUNET_PEER_resolve(p->peers[i], &peer_id);
        memcpy(&peer_ptr[i], &peer_id, sizeof(struct GNUNET_PeerIdentity));
    }

    peer_info->state = MESH_PEER_WAITING;

    return size_needed;
}


/**
 * Core handler for path creation
 * struct GNUNET_CORE_MessageHandler
 *
 * @param cls closure
 * @param message message
 * @param peer peer identity this notification is about
 * @param atsi performance data
 * @return GNUNET_OK to keep the connection open,
 *         GNUNET_SYSERR to close it (signal serious error)
 *
 */
static int
handle_mesh_path_create (void *cls,
                              const struct GNUNET_PeerIdentity *peer,
                              const struct GNUNET_MessageHeader *message,
                              const struct GNUNET_TRANSPORT_ATS_Information
                              *atsi)
{
    /* Extract path */
    /* Find origin & self */
    /* Search for origin in local tunnels */
    /* Create tunnel / add path */
    /* Retransmit to next link in chain, if any (core_notify + callback) */
    return GNUNET_OK;
}

/**
 * Core handler for mesh network traffic
 *
 * @param cls closure
 * @param message message
 * @param peer peer identity this notification is about
 * @param atsi performance data
 * @return GNUNET_OK to keep the connection open,
 *         GNUNET_SYSERR to close it (signal serious error)
 */
static int
handle_mesh_network_traffic (void *cls,
                             const struct GNUNET_PeerIdentity *peer,
                             const struct GNUNET_MessageHeader *message,
                             const struct GNUNET_TRANSPORT_ATS_Information
                             *atsi)
{
    if(GNUNET_MESSAGE_TYPE_MESH_DATA_GO == ntohs(message->type)) {
        /* Retransmit to next in path of tunnel identified by message */
        return GNUNET_OK;
    } else { /* GNUNET_MESSAGE_TYPE_MESH_DATA_BACK */
        /* Retransmit to previous in path of tunnel identified by message */
        return GNUNET_OK;
    }
}

/**
 * Functions to handle messages from core
 */
static struct GNUNET_CORE_MessageHandler core_handlers[] = {
  {&handle_mesh_path_create, GNUNET_MESSAGE_TYPE_MESH_PATH_CREATE, 0},
  {&handle_mesh_network_traffic, GNUNET_MESSAGE_TYPE_MESH_DATA_GO, 0},
  {&handle_mesh_network_traffic, GNUNET_MESSAGE_TYPE_MESH_DATA_BACK, 0},
  {NULL, 0, 0}
};



/******************************************************************************/
/*********************       MESH LOCAL HANDLES      **************************/
/******************************************************************************/

/**
 * notify_client_connection_failure: notify a client that the connection to the
 * requested remote peer is not possible (for instance, no route found)
 * Function called when the socket is ready to queue more data."buf" will be
 * NULL and "size" zero if the socket was closed for writing in the meantime.
 *
 * @param cls closure
 * @param size number of bytes available in buf
 * @param buf where the callee should write the message
 * @return number of bytes written to buf
 */
static size_t
notify_client_connection_failure (void *cls, size_t size, void *buf) {
    int                                 size_needed;
    struct PeerInfo                     *peer_info;
    struct GNUNET_MESH_PeerControl      *msg;
    struct GNUNET_PeerIdentity          id;

    if(0 == size && NULL == buf) {
        // TODO retry? cancel?
        return 0;
    }

    size_needed = sizeof(struct GNUNET_MESH_PeerControl);
    peer_info = (struct PeerInfo *) cls;
    msg = (struct GNUNET_MESH_PeerControl *) buf;
    msg->header.size = htons(sizeof(struct GNUNET_MESH_PeerControl));
    msg->header.type = htons(GNUNET_MESSAGE_TYPE_MESH_LOCAL_PEER_DISCONNECTED);
    msg->tunnel_id = htonl(peer_info->t->tid);
    GNUNET_PEER_resolve(peer_info->id, &id);
    memcpy(&msg->peer, &id, sizeof(struct GNUNET_PeerIdentity));

    return size_needed;
}


/**
 * Function to process paths received for a new peer addition. The recorded
 * paths form the initial tunnel, which can be optimized later.
 * Called on each result obtained for the DHT search.
 *
 * @param cls closure
 * @param exp when will this value expire
 * @param key key of the result
 * @param get_path NULL-terminated array of pointers
 *                 to the peers on reverse GET path (or NULL if not recorded)
 * @param put_path NULL-terminated array of pointers
 *                 to the peers on the PUT path (or NULL if not recorded)
 * @param type type of the result
 * @param size number of bytes in data
 * @param data pointer to the result data
 */
static void
dht_get_response_handler(void *cls,
                        struct GNUNET_TIME_Absolute exp,
                        const GNUNET_HashCode * key,
                        const struct GNUNET_PeerIdentity * const *get_path,
                        const struct GNUNET_PeerIdentity * const *put_path,
                        enum GNUNET_BLOCK_Type type,
                        size_t size,
                        const void *data)
{
    struct PeerInfo             *peer_info;
    struct MESH_tunnel          *t;
    struct Path                 *p;
    int                         i;

    peer_info = (struct PeerInfo *)cls;
    t = peer_info->t;

    if(NULL == get_path || NULL == put_path) {
        // TODO: find ourselves some alternate initial path to the destination
        GNUNET_SERVER_notify_transmit_ready(
            t->client->handle,
            sizeof(struct GNUNET_MESH_PeerControl),
            GNUNET_TIME_relative_get_forever(),
            &notify_client_connection_failure,
            peer_info
        );
    }

    p = GNUNET_malloc(sizeof(struct Path));
    GNUNET_CONTAINER_DLL_insert(t->paths_head, t->paths_tail, p);
    for(i = 0; get_path[i] != NULL; i++);
    for(i--; i >= 0; i--) {
        p->peers = GNUNET_realloc(p->peers,
                                   sizeof(GNUNET_PEER_Id) * (p->length + 1));
        p->peers[p->length] = GNUNET_PEER_intern(get_path[i]);
        p->length++;
    }
    for(i = 0; put_path[i] != NULL; i++);
    for(i--; i >= 0; i--) {
        p->peers = GNUNET_realloc(p->peers,
                                  sizeof(GNUNET_PEER_Id) * (p->length + 1));
        p->peers[p->length] = GNUNET_PEER_intern(put_path[i]);
        p->length++;
    }
    // p->id = 0; // FIXME generate ID or remove field
    p->in_use = 0;
    // peer_info->first_hop = p->peers[1]; // FIXME do this on path completion
    GNUNET_CORE_notify_transmit_ready(core_handle,
                                      0,
                                      0,
                                      GNUNET_TIME_relative_get_forever(),
                                      get_path[1],
                                      sizeof(struct GNUNET_MESH_ManipulatePath)
                                        + (p->length
                                        * sizeof (struct GNUNET_PeerIdentity)),
                                      &send_core_create_path_for_peer,
                                      peer_info
                                     );
    return;
}

/**
 * Handler for client disconnection
 *
 * @param cls closure
 * @param client identification of the client; NULL
 *        for the last call when the server is destroyed
 */
static void
handle_client_disconnect (void *cls, struct GNUNET_SERVER_Client *client)
{
    struct Client       *c, *next;
    struct MESH_tunnel  *t;

    c = clients_head;
    while(NULL != c) {
        if (c->handle == client) {
            GNUNET_CONTAINER_DLL_remove (clients_head, clients_tail, c);
            while (NULL != (t = c->tunnels_head)) {
                destroy_tunnel(c, t);
            }
            GNUNET_free (c->messages_subscribed);
            next = c->next;
            GNUNET_free (c);
            c = next;
        } else {
            c = c->next;
        }
    }
    return;
}

/**
 * Handler for new clients
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message, which includes messages the client wants
 */
static void
handle_local_new_client (void *cls,
                         struct GNUNET_SERVER_Client *client,
                         const struct GNUNET_MessageHeader *message)
{
    struct Client               *c;
    unsigned int                payload_size;

    /* Check data sanity */
    payload_size = message->size - sizeof(struct GNUNET_MessageHeader);
    if (0 != payload_size % sizeof(GNUNET_MESH_ApplicationType)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Create new client structure */
    c = GNUNET_malloc(sizeof(struct Client));
    c->handle = client;
    c->tunnels_head = NULL;
    c->tunnels_tail = NULL;
    if(payload_size != 0) {
        c->messages_subscribed = GNUNET_malloc(payload_size);
        memcpy(c->messages_subscribed, &message[1], payload_size);
    } else {
        c->messages_subscribed = NULL;
    }
    c->subscription_counter = payload_size/sizeof(GNUNET_MESH_ApplicationType);

    /* Insert new client in DLL */
    GNUNET_CONTAINER_DLL_insert (clients_head, clients_tail, c);

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
}

/**
 * Handler for requests of new tunnels
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_local_tunnel_create (void *cls,
                            struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *message)
{
    struct GNUNET_MESH_TunnelMessage    *tunnel_msg;
    struct MESH_tunnel                  *t;
    struct Client                       *c;

    /* Sanity check for client registration */
    if(NULL == (c = retrieve_client(client))) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Message sanity check */
    if(sizeof(struct GNUNET_MESH_TunnelMessage) != ntohs(message->size)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    tunnel_msg = (struct GNUNET_MESH_TunnelMessage *) message;
    /* Sanity check for tunnel numbering */
    if(0 == (ntohl(tunnel_msg->tunnel_id) & 0x80000000)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }
    /* Sanity check for duplicate tunnel IDs */
    t = c->tunnels_head;
    while(NULL != t) {
        if(t->tid == ntohl(tunnel_msg->tunnel_id)) {
            GNUNET_break(0);
            GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
            return;
        }
        t = t->next;
    }
    /* FIXME: calloc? Is NULL != 0 on any platform? */
    t = GNUNET_malloc(sizeof(struct MESH_tunnel));
    t->tid = ntohl(tunnel_msg->tunnel_id);
    t->oid = myid;
    t->peers_ready = 0;
    t->peers_total = 0;
    t->peers_head = NULL;
    t->peers_tail = NULL;
    t->paths_head = NULL;
    t->paths_tail = NULL;
    t->in_head = NULL;
    t->in_tail = NULL;
    t->out_head = NULL;
    t->out_tail = NULL;
    t->client = c;

    GNUNET_CONTAINER_DLL_insert(c->tunnels_head, c->tunnels_tail, t);

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
    return;
}

/**
 * Handler for requests of deleting tunnels
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_local_tunnel_destroy (void *cls,
                             struct GNUNET_SERVER_Client *client,
                             const struct GNUNET_MessageHeader *message)
{
    struct GNUNET_MESH_TunnelMessage    *tunnel_msg;
    struct Client                       *c;
    struct MESH_tunnel                  *t;
    MESH_TunnelID                       tid;

    /* Sanity check for client registration */
    if(NULL == (c = retrieve_client(client))) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }
    /* Message sanity check */
    if(sizeof(struct GNUNET_MESH_TunnelMessage) != ntohs(message->size)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    tunnel_msg = (struct GNUNET_MESH_TunnelMessage *) message;

    /* Tunnel exists? */
    tid = ntohl(tunnel_msg->tunnel_id);
    if(NULL == (t = c->tunnels_head)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }
    while(NULL != t) {
        if(t->tid == tid) {
            break;
        }
        if(t == c->tunnels_tail) {
            GNUNET_break(0);
            GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
            return;
        }
        t = t->next;
    }

    destroy_tunnel(c, t);

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
    return;
}

/**
 * Handler for connection requests to new peers
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message (PeerControl)
 */
static void
handle_local_connect_add (void *cls,
                          struct GNUNET_SERVER_Client *client,
                          const struct GNUNET_MessageHeader *message)
{
    struct GNUNET_MESH_PeerControl      *peer_msg;
    struct Client                       *c;
    struct MESH_tunnel                  *t;
    MESH_TunnelID                       tid;
    struct PeerInfo                     *peer_info;

    GNUNET_HashCode                     key;


    /* Sanity check for client registration */
    if(NULL == (c = retrieve_client(client))) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    peer_msg = (struct GNUNET_MESH_PeerControl *)message;
    /* Sanity check for message size */
    if(sizeof(struct GNUNET_MESH_PeerControl) != ntohs(peer_msg->header.size)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Tunnel exists? */
    tid = ntohl(peer_msg->tunnel_id);
    t = c->tunnels_head;
    while(NULL != t) {
        if(t->tid == tid) {
            break;
        }
        t = t->next;
    }
    if(NULL == t) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Does client own tunnel? */
    if(t->client->handle != client) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Ok, add peer to tunnel */
    peer_info = (struct PeerInfo *) GNUNET_malloc(sizeof(struct PeerInfo));
    peer_info->id = GNUNET_PEER_intern(&peer_msg->peer);
    peer_info->state = MESH_PEER_SEARCHING;
    peer_info->t = t;
    t->peers_total++;
    GNUNET_CONTAINER_DLL_insert(t->peers_head, t->peers_tail, peer_info);
    /* Start DHT search */
    GNUNET_CRYPTO_hash (&peer_msg->peer,
                        sizeof(struct GNUNET_PeerIdentity),
                        &key);
    peer_info->dhtget = GNUNET_DHT_get_start(dht_handle,
                                            GNUNET_TIME_relative_get_forever(),
                                            GNUNET_BLOCK_TYPE_ANY,
                                            &key,
                                            4,    /* replication level */
                                            GNUNET_DHT_RO_RECORD_ROUTE,
                                            NULL, /* bloom filter */
                                            0,    /* mutator */
                                            NULL, /* xquery */
                                            0,    /* xquery bits */
                                            dht_get_response_handler,
                                            (void *)peer_info);

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
    return;
}


/**
 * Handler for disconnection requests of peers in a tunnel
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message (PeerControl)
 */
static void
handle_local_connect_del (void *cls,
                          struct GNUNET_SERVER_Client *client,
                          const struct GNUNET_MessageHeader *message)
{
    struct GNUNET_MESH_PeerControl      *peer_msg;
    struct Client                       *c;
    struct MESH_tunnel                  *t;
    struct Path                         *p;
    struct Path                         *aux_path;
    MESH_TunnelID                       tid;
    GNUNET_PEER_Id                      peer_id;
    struct PeerInfo                     *peer_info;
    struct PeerInfo                     *aux_peer_info;

    /* Sanity check for client registration */
    if(NULL == (c = retrieve_client(client))) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }
    peer_msg = (struct GNUNET_MESH_PeerControl *)message;
    /* Sanity check for message size */
    if(sizeof(struct GNUNET_MESH_PeerControl) != ntohs(peer_msg->header.size)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Tunnel exists? */
    tid = ntohl(peer_msg->tunnel_id);
    if(NULL == (t = c->tunnels_head)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }
    while(NULL != t) {
        if(t->tid == tid) {
            break;
        }
        if(t == c->tunnels_tail) {
            GNUNET_break(0);
            GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
            return;
        }
        t = t->next;
    }
    if(NULL == t) {
            GNUNET_break(0);
            GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
            return;
        }

    /* Does client own tunnel? */
    if(t->client->handle != client) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Ok, delete peer from tunnel */
    peer_id = GNUNET_PEER_intern(&peer_msg->peer);

    /* Delete paths */
    p = t->paths_head;
    while(p != NULL) {
        if(p->peers[p->length-1] == peer_id) { /* one path per destination */
            GNUNET_CONTAINER_DLL_remove(t->paths_head, t->paths_tail, p);
            GNUNET_PEER_decrement_rcs(p->peers, p->length);
            aux_path = p;
            p = p->next;
            GNUNET_free(aux_path);
        } else {
            p = p->next;
        }
    }

    /*Delete peer info */
    peer_info = t->peers_head;
    while(peer_info != NULL) {
        if(peer_info->id == peer_id) {
            GNUNET_CONTAINER_DLL_remove(t->peers_head,
                                        t->peers_tail,
                                        peer_info);
            aux_peer_info = peer_info;
            peer_info = peer_info->next;
            GNUNET_free(aux_peer_info);
        } else {
            peer_info = peer_info->next;
        }
    }

    GNUNET_PEER_change_rc(peer_id, -1);

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
    return;
}


/**
 * Handler for connection requests to new peers by type
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message (ConnectPeerByType)
 */
static void
handle_local_connect_by_type (void *cls,
                              struct GNUNET_SERVER_Client *client,
                              const struct GNUNET_MessageHeader *message)
{
    struct GNUNET_MESH_ConnectPeerByType        *connect_msg;
    MESH_TunnelID                               tid;
    GNUNET_MESH_ApplicationType                 application;
    struct Client                               *c;
    struct MESH_tunnel                          *t;

    /* Sanity check for client registration */
    if(NULL == (c = retrieve_client(client))) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    connect_msg = (struct GNUNET_MESH_ConnectPeerByType *)message;
    /* Sanity check for message size */
    if(sizeof(struct GNUNET_MESH_PeerControl) != ntohs(connect_msg->header.size)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Tunnel exists? */
    tid = ntohl(connect_msg->tunnel_id);
    t = c->tunnels_head;
    while(NULL != t) {
        if(t->tid == tid) {
            break;
        }
        t = t->next;
    }
    if(NULL == t) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Does client own tunnel? */
    if(t->client->handle != client) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Ok, lets find a peer offering the service */
    application = ntohl(connect_msg->type);
    application++; // FIXME silence warnings

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
    return;
}


/**
 * Handler for client traffic directed to one peer
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_local_network_traffic (void *cls,
                         struct GNUNET_SERVER_Client *client,
                         const struct GNUNET_MessageHeader *message)
{
    struct Client                               *c;
    struct MESH_tunnel                          *t;
    struct GNUNET_MESH_Data                     *data_msg;
    MESH_TunnelID                               tid;

    /* Sanity check for client registration */
    if(NULL == (c = retrieve_client(client))) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }
    data_msg = (struct GNUNET_MESH_Data *)message;
    /* Sanity check for message size */
    if(sizeof(struct GNUNET_MESH_PeerControl) != ntohs(data_msg->header.size)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Tunnel exists? */
    tid = ntohl(data_msg->tunnel_id);
    t = c->tunnels_head;
    while(NULL != t) {
        if(t->tid == tid) {
            break;
        }
        t = t->next;
    }
    if(NULL == t) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Does client own tunnel? */
    if(t->client->handle != client) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* TODO */

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
    return;
}

/**
 * Handler for client traffic directed to all peers in a tunnel
 * 
 * @param cls closure
 * @param client identification of the client
 * @param message the actual message
 */
static void
handle_local_network_traffic_bcast (void *cls,
                                    struct GNUNET_SERVER_Client *client,
                                    const struct GNUNET_MessageHeader *message)
{
    struct Client                               *c;
    struct MESH_tunnel                          *t;
    struct GNUNET_MESH_DataBroadcast            *data_msg;
    MESH_TunnelID                               tid;

    /* Sanity check for client registration */
    if(NULL == (c = retrieve_client(client))) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }
    data_msg = (struct GNUNET_MESH_DataBroadcast *)message;
    /* Sanity check for message size */
    if(sizeof(struct GNUNET_MESH_PeerControl) != ntohs(data_msg->header.size)) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Tunnel exists? */
    tid = ntohl(data_msg->tunnel_id);
    t = c->tunnels_head;
    while(NULL != t) {
        if(t->tid == tid) {
            break;
        }
        t = t->next;
    }
    if(NULL == t) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /* Does client own tunnel? */
    if(t->client->handle != client) {
        GNUNET_break(0);
        GNUNET_SERVER_receive_done(client, GNUNET_SYSERR);
        return;
    }

    /*  TODO */

    GNUNET_SERVER_receive_done(client, GNUNET_OK);
    return;
}

/**
 * Functions to handle messages from clients
 */
static struct GNUNET_SERVER_MessageHandler plugin_handlers[] = {
  {&handle_local_new_client, NULL, GNUNET_MESSAGE_TYPE_MESH_LOCAL_CONNECT, 0},
  {&handle_local_tunnel_create, NULL,
   GNUNET_MESSAGE_TYPE_MESH_LOCAL_TUNNEL_CREATE,
   sizeof(struct GNUNET_MESH_TunnelMessage)},
  {&handle_local_tunnel_destroy, NULL,
   GNUNET_MESSAGE_TYPE_MESH_LOCAL_TUNNEL_DESTROY,
   sizeof(struct GNUNET_MESH_TunnelMessage)},
  {&handle_local_connect_add, NULL,
   GNUNET_MESSAGE_TYPE_MESH_LOCAL_CONNECT_PEER_ADD,
   sizeof(struct GNUNET_MESH_PeerControl)},
  {&handle_local_connect_del, NULL,
   GNUNET_MESSAGE_TYPE_MESH_LOCAL_CONNECT_PEER_DEL,
   sizeof(struct GNUNET_MESH_PeerControl)},
  {&handle_local_connect_by_type, NULL,
   GNUNET_MESSAGE_TYPE_MESH_LOCAL_CONNECT_PEER_BY_TYPE,
   sizeof(struct GNUNET_MESH_ConnectPeerByType)},
  {&handle_local_network_traffic, NULL,
   GNUNET_MESSAGE_TYPE_MESH_LOCAL_DATA, 0},
  {&handle_local_network_traffic_bcast, NULL,
   GNUNET_MESSAGE_TYPE_MESH_LOCAL_DATA_BROADCAST, 0},
  {NULL, NULL, 0, 0}
};


/**
 * To be called on core init/fail.
 *
 * @param cls service closure
 * @param server handle to the server for this service
 * @param identity the public identity of this peer
 * @param publicKey the public key of this peer
 */
static void
core_init (void *cls,
           struct GNUNET_CORE_Handle *server,
           const struct GNUNET_PeerIdentity *identity,
           const struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded *publicKey)
{
    core_handle = server;
    myid = GNUNET_PEER_intern(identity);
    return;
}

/**
 * Method called whenever a given peer connects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 * @param atsi performance data for the connection
 */
static void
core_connect (void *cls,
              const struct GNUNET_PeerIdentity *peer,
              const struct GNUNET_TRANSPORT_ATS_Information *atsi)
{
    return;
}

/**
 * Method called whenever a peer disconnects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 */
static void
core_disconnect (void *cls,
                const struct
                GNUNET_PeerIdentity *peer)
{
    return;
}

/******************************************************************************/
/************************      MAIN FUNCTIONS      ****************************/
/******************************************************************************/

/**
 * Process mesh requests.
 *
 * @param cls closure
 * @param server the initialized server
 * @param c configuration to use
 */
static void
run (void *cls,
     struct GNUNET_SERVER_Handle *server,
     const struct GNUNET_CONFIGURATION_Handle *c)
{

    GNUNET_SERVER_add_handlers (server, plugin_handlers);
    GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, NULL);
    core_handle = GNUNET_CORE_connect (c,               /* Main configuration */
                            32,                                 /* queue size */
                            NULL,         /* Closure passed to MESH functions */
                            &core_init,      /* Call core_init once connected */
                            &core_connect,                 /* Handle connects */
                            &core_disconnect,  /* remove peers on disconnects */
                            NULL,       /* Do we care about "status" updates? */
                            NULL, /* Don't notify about all incoming messages */
                            GNUNET_NO,     /* For header only in notification */
                            NULL, /* Don't notify about all outbound messages */
                            GNUNET_NO,    /* For header-only out notification */
                            core_handlers);        /* Register these handlers */

    if (core_handle == NULL) {
        GNUNET_break(0);
    }

    dht_handle = GNUNET_DHT_connect(c, 100); /* FIXME ht len correct size? */
    if (dht_handle == NULL) {
        GNUNET_break(0);
    }
}

/**
 * The main function for the mesh service.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *const *argv)
{
    int ret;

    ret = (GNUNET_OK ==
           GNUNET_SERVICE_run (argc,
                               argv,
                               "mesh",
                               GNUNET_SERVICE_OPTION_NONE,
                               &run, NULL)) ? 0 : 1;
    return ret;
    }