PeerStreamer

/*

 *          Policy Management

 *

 *          NEC Europe Ltd. PROPRIETARY INFORMATION

 *

 * This software is supplied under the terms of a license agreement

 * or nondisclosure agreement with NEC Europe Ltd. and may not be

 * copied or disclosed except in accordance with the terms of that

 * agreement.

 *

 *      Copyright (c) 2009 NEC Europe Ltd. All Rights Reserved.

 *

 * Authors: Kristian Beckers  <beckers@nw.neclab.eu>

 *          Sebastian Kiesel  <kiesel@nw.neclab.eu>

 *          

 *

 * NEC Europe Ltd. DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED,

 * INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY

 * AND FITNESS FOR A PARTICULAR PURPOSE AND THE WARRANTY AGAINST LATENT

 * DEFECTS, WITH RESPECT TO THE PROGRAM AND THE ACCOMPANYING

 * DOCUMENTATION.

 *

 * No Liability For Consequential Damages IN NO EVENT SHALL NEC Europe

 * Ltd., NEC Corporation OR ANY OF ITS SUBSIDIARIES BE LIABLE FOR ANY

 * DAMAGES WHATSOEVER (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS

 * OF BUSINESS PROFITS, BUSINESS INTERRUPTION, LOSS OF INFORMATION, OR

 * OTHER PECUNIARY LOSS AND INDIRECT, CONSEQUENTIAL, INCIDENTAL,

 * ECONOMIC OR PUNITIVE DAMAGES) ARISING OUT OF THE USE OF OR INABILITY

 * TO USE THIS PROGRAM, EVEN IF NEC Europe Ltd. HAS BEEN ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGES.

 *

 *     THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.

 */

#include <arpa/inet.h>

#ifndef WIN32

#include <netinet/in.h>

#include <sys/socket.h>

#endif

#include <fcntl.h>

#include <event2/event.h>

#include <stdlib.h>

#include <unistd.h>

#include <stdio.h>

#include <stddef.h>

#include <stdint.h>

#include <string.h>

#include <sys/types.h>

#include <arpa/inet.h>

#include <netdb.h>

#include <errno.h>

#include <time.h>

#include <math.h>

#include <assert.h>

#include "msg_types.h"

#include "util/udpSocket.h"

#include "util/stun.h"

#include "transmissionHandler.h"

#define LOG_MODULE "[ml] "

#include "ml_log.h"

/**************************** START OF INTERNALS ***********************/

/*

 * a pointer to a libevent instance

 */

struct event_base *base;

/*

 * define the nr of connections the messaging layer can handle

 */

#define CONNECTBUFSIZE 10000

/*

 * define the nr of data that can be received parallel

 */

#define RECVDATABUFSIZE 10000

/*

 * define an array for message multiplexing

 */

#define MSGMULTIPLEXSIZE 127

/*

 * timeout before thinking that the STUN server can't be connected

 */

#define NAT_TRAVERSAL_TIMEOUT { 1, 0 }

/*

 * timeout before thinking of an mtu problem (check MAX_TRIALS as well)

 */

#define PMTU_TIMEOUT { 0, 500000 }

/*

 * retry sending connection messages this many times before reducing pmtu

 */

#define MAX_TRIALS 3

/*

 * default timeout value between the first and the last received packet of a message

 */

#define RECV_TIMEOUT_DEFAULT { 2, 0 }

/*

 * global variables

 */

/*

 * define a buffer of pointers to connect structures

 */

connect_data *connectbuf[CONNECTBUFSIZE];

/*

 * define a pointer buffer with pointers to recv_data structures

 */

recvdata *recvdatabuf[RECVDATABUFSIZE];

/*

 * define a pointer buffer for message multiplexing

 */

receive_data_cb recvcbbuf[MSGMULTIPLEXSIZE];

/*

 * stun server address

 */

struct sockaddr_in stun_server;

/*

 * receive timeout

 */

static struct timeval recv_timeout = RECV_TIMEOUT_DEFAULT;

/*

 * boolean NAT traversal successful if true

 */

boolean NAT_traversal;

/*

 * file descriptor for local socket

 */

evutil_socket_t socketfd;

/*

 * local socketID

 */

socket_ID local_socketID;

socketID_handle loc_socketID = &local_socketID;

/*

 * callback function pointers

 */

/*

 * monitoring module callbacks

 */

get_recv_pkt_inf_cb get_Recv_pkt_inf_cb = NULL;

get_send_pkt_inf_cb get_Send_pkt_inf_cb = NULL;

set_monitoring_header_pkt_cb set_Monitoring_header_pkt_cb = NULL;

get_recv_data_inf_cb get_Recv_data_inf_cb = NULL;

get_send_data_inf_cb get_Send_data_inf_cb = NULL;

set_monitoring_header_data_cb set_Monitoring_header_data_cb = NULL;

/*

 * connection callbacks

 */

receive_connection_cb receive_Connection_cb = NULL;

connection_failed_cb failed_Connection_cb = NULL;

/*

 * local socketID callback

 */

receive_localsocketID_cb receive_SocketID_cb;

/*

 * boolean that defines if received data is transmitted to the upper layer

 * via callback or via upper layer polling

 */

boolean recv_data_callback;

/*

 * helper function to get rid of a warning

 */

int min(int a, int b) {

        if (a > b) return b;

        return a;

}

/*

 * convert a socketID to a string. It uses a static buffer, so either strdup is needed, or the string will get lost!

 */

const char *conid_to_string(int con_id)

{

        static char s[INET_ADDRSTRLEN+1+5+1+INET_ADDRSTRLEN+1+5+1];

        mlSocketIDToString(&connectbuf[con_id]->external_socketID, s, sizeof(s));

        return s;

}

void register_recv_localsocketID_cb(receive_localsocketID_cb local_socketID_cb)

{

        if (local_socketID_cb == NULL)

                error("ML : Register receive_localsocketID_cb: NULL ptr \n");

        else

        receive_SocketID_cb = local_socketID_cb;

}

//void keep_connection_alive(const int connectionID)

//{

//

//    // to be done with the NAT traversal

//    // send a message over the wire

//    printf("\n");

//

//}

void unsetStunServer()

{

        stun_server.sin_addr.s_addr = INADDR_NONE;

}

bool isStunDefined()

{

        return stun_server.sin_addr.s_addr != INADDR_NONE;

}

void send_msg(int con_id, int msg_type, char* msg, int msg_len, bool truncable, send_params * sParams) {

        socketaddrgen udpgen;

        bool retry;

        int pkt_len, offset;

        struct iovec iov[4];

        char h_pkt[MON_PKT_HEADER_SPACE];

        char h_data[MON_DATA_HEADER_SPACE];

        struct msg_header msg_h;

        debug("ML: send_msg to %s conID:%d extID:%d\n", conid_to_string(con_id), con_id, connectbuf[con_id]->external_connectionID);

        iov[0].iov_base = &msg_h;

        iov[0].iov_len = MSG_HEADER_SIZE;

        msg_h.local_con_id = con_id;

        msg_h.remote_con_id = connectbuf[con_id]->external_connectionID;

        msg_h.msg_type = msg_type;

        msg_h.msg_seq_num = connectbuf[con_id]->seqnr++;

        iov[1].iov_len = iov[2].iov_len = 0;

        iov[1].iov_base = h_pkt;

        iov[2].iov_base = h_data;

        if (connectbuf[con_id]->internal_connect)

                udpgen = connectbuf[con_id]->external_socketID.internal_addr;

        else

                udpgen = connectbuf[con_id]->external_socketID.external_addr;

        do{

                offset = 0;

                retry = false;

                // Monitoring layer hook

                if(set_Monitoring_header_data_cb != NULL) {

                        iov[2].iov_len = ((set_Monitoring_header_data_cb) (&(connectbuf[con_id]->external_socketID), msg_type));

                }

                msg_h.len_mon_data_hdr = iov[2].iov_len;

                if(get_Send_data_inf_cb != NULL && iov[2].iov_len != 0) {

                        mon_data_inf sd_data_inf;

                        memset(h_data, 0, MON_DATA_HEADER_SPACE);

                        sd_data_inf.remote_socketID = &(connectbuf[con_id]->external_socketID);

                        sd_data_inf.buffer = msg;

                        sd_data_inf.bufSize = msg_len;

                        sd_data_inf.msgtype = msg_type;

                        sd_data_inf.monitoringDataHeader = iov[2].iov_base;

                        sd_data_inf.monitoringDataHeaderLen = iov[2].iov_len;

                        sd_data_inf.priority = sParams->priority;

                        sd_data_inf.padding = sParams->padding;

                        sd_data_inf.confirmation = sParams->confirmation;

                        sd_data_inf.reliable = sParams->reliable;

                        memset(&sd_data_inf.arrival_time, 0, sizeof(struct timeval));

                        (get_Send_data_inf_cb) ((void *) &sd_data_inf);

                }

                do {

                        if(set_Monitoring_header_pkt_cb != NULL) {

                                iov[1].iov_len = (set_Monitoring_header_pkt_cb) (&(connectbuf[con_id]->external_socketID), msg_type);

                        }

                        pkt_len = min(connectbuf[con_id]->pmtusize - iov[2].iov_len - iov[1].iov_len - iov[0].iov_len, msg_len - offset) ;

                        iov[3].iov_len = pkt_len;

                        iov[3].iov_base = msg + offset;

                        //fill header

                        msg_h.len_mon_packet_hdr = iov[1].iov_len;

                        msg_h.offset = offset;

                        msg_h.msg_length = truncable ? pkt_len : msg_len;

                        //monitoring layer hook

                        if(get_Send_pkt_inf_cb != NULL && iov[1].iov_len) {

                                mon_pkt_inf pkt_info;

                                memset(h_pkt,0,MON_PKT_HEADER_SPACE);

                                pkt_info.remote_socketID = &(connectbuf[con_id]->external_socketID);

                                pkt_info.buffer = msg + offset;

                                pkt_info.bufSize = pkt_len;

                                pkt_info.msgtype = msg_type;

                                pkt_info.dataID = connectbuf[con_id]->seqnr;

                                pkt_info.offset = offset;

                                pkt_info.datasize = msg_len;

                                pkt_info.monitoringHeaderLen = iov[1].iov_len;

                                pkt_info.monitoringHeader = iov[1].iov_base;

                                pkt_info.ttl = -1;

                                memset(&(pkt_info.arrival_time),0,sizeof(struct timeval));

                                (get_Send_pkt_inf_cb) ((void *) &pkt_info);

                        }

                        debug("ML: sending packet to %s with rconID:%d lconID:%d\n", conid_to_string(con_id), msg_h.remote_con_id, msg_h.local_con_id);

                        switch(sendPacket(socketfd, iov, 4, &udpgen.udpaddr)) {

                                case MSGLEN:

                                        info("ML: sending message failed, reducing MTU from %d to %d (to:%s conID:%d lconID:%d msgsize:%d offset:%d)\n", connectbuf[con_id]->pmtusize, pmtu_decrement(connectbuf[con_id]->pmtusize), conid_to_string(con_id), msg_h.remote_con_id, msg_h.local_con_id, msg_len, offset);

                                        // TODO: pmtu decremented here, but not in the "truncable" packet. That is currently resent without changing the claimed pmtu. Might need to be changed.

                                        connectbuf[con_id]->pmtusize = pmtu_decrement(connectbuf[con_id]->pmtusize);

                                        if (connectbuf[con_id]->pmtusize > 0) {

                                                connectbuf[con_id]->delay = true;

                                                retry = true;

                                        }

                                        offset = msg_len; // exit the while

                                        break;

                                case FAILURE:

                                        info("ML: sending message failed (to:%s conID:%d lconID:%d msgsize:%d offset:%d)\n", conid_to_string(con_id), msg_h.remote_con_id, msg_h.local_con_id, msg_len, offset);

                                        offset = msg_len; // exit the while

                                        break;

                                case OK:

                                        //update

                                        offset += pkt_len;

                                        //transmit data header only in the first packet

                                        iov[2].iov_len = 0;

                                        break;

                        }

                } while(offset != msg_len && !truncable);

        } while(retry);

}

void pmtu_timeout_cb(int fd, short event, void *arg);

void reschedule_conn_msg(int con_id)

{

        if (connectbuf[con_id]->timeout_event) {

                /* delete old timout */        

                event_del(connectbuf[con_id]->timeout_event);

                event_free(connectbuf[con_id]->timeout_event);

        }

        connectbuf[con_id]->timeout_event = event_new(base, -1, EV_TIMEOUT, &pmtu_timeout_cb, (void *) (long)con_id);

        evtimer_add(connectbuf[con_id]->timeout_event, &connectbuf[con_id]->timeout_value);

}

void send_conn_msg(int con_id, int buf_size, int command_type)

{

        if (buf_size < sizeof(struct conn_msg)) {

                error("ML: requested connection message size is too small\n");

                return;

        }

        if(connectbuf[con_id]->ctrl_msg_buf == NULL) {

                connectbuf[con_id]->ctrl_msg_buf = malloc(buf_size);

                memset(connectbuf[con_id]->ctrl_msg_buf, 0, buf_size);

        }

        if(connectbuf[con_id]->ctrl_msg_buf == NULL) {

                error("ML: can not allocate memory for connection message\n");

                return;

        }

        struct conn_msg *msg_header = (struct conn_msg*) connectbuf[con_id]->ctrl_msg_buf;

        msg_header->comand_type = command_type;

        msg_header->pmtu_size = connectbuf[con_id]->pmtusize;

        memcpy(&(msg_header->sock_id), loc_socketID, sizeof(socket_ID));

        send_msg(con_id, ML_CON_MSG, connectbuf[con_id]->ctrl_msg_buf, buf_size, true, &(connectbuf[con_id]->defaultSendParams));

}

void send_conn_msg_with_pmtu_discovery(int con_id, int buf_size, int command_type)

{

        struct timeval tout = PMTU_TIMEOUT;

        connectbuf[con_id]->timeout_value = tout;

        connectbuf[con_id]->trials = 1;

        send_conn_msg(con_id, buf_size, command_type);

        reschedule_conn_msg(con_id);

}

void resend_conn_msg(int con_id)

{

        connectbuf[con_id]->trials++;

        send_conn_msg(con_id, connectbuf[con_id]->pmtusize, connectbuf[con_id]->status);

        reschedule_conn_msg(con_id);

}

void recv_conn_msg(struct msg_header *msg_h, char *msgbuf, int msg_size, struct sockaddr_in *recv_addr)

{

        struct conn_msg *con_msg;

        int free_con_id, con_id;

        time_t now = time(NULL);

        double timediff = 0.0;

        char sock_id_str[1000];

        msgbuf += msg_h->len_mon_data_hdr;

        msg_size -= msg_h->len_mon_data_hdr;

        con_msg = (struct conn_msg *)msgbuf;

        //verify message validity

        if (msg_size < sizeof(struct conn_msg)) {

                char recv_addr_str[INET_ADDRSTRLEN];

                inet_ntop(AF_INET, &(recv_addr->sin_addr.s_addr), recv_addr_str, INET_ADDRSTRLEN);

                info("Invalid conn_msg received from %s\n", recv_addr_str);

                return;

        }

        //decode sock_id for debug messages

        mlSocketIDToString(&con_msg->sock_id,sock_id_str,999);

        if (con_msg->sock_id.internal_addr.udpaddr.sin_addr.s_addr != recv_addr->sin_addr.s_addr &&

            con_msg->sock_id.external_addr.udpaddr.sin_addr.s_addr != recv_addr->sin_addr.s_addr   ) {

                char recv_addr_str[INET_ADDRSTRLEN];

                inet_ntop(AF_INET, &(recv_addr->sin_addr.s_addr), recv_addr_str, INET_ADDRSTRLEN);

                info("Conn msg received from %s, but claims to be from %s", recv_addr_str, sock_id_str);

                return;

        }

        // Monitoring layer hook

        if(get_Recv_data_inf_cb != NULL) {

                // update pointer to the real data

                mon_data_inf recv_data_inf;

                recv_data_inf.remote_socketID = &(con_msg->sock_id);

                recv_data_inf.buffer = msgbuf;

                recv_data_inf.bufSize = msg_size;

                recv_data_inf.msgtype = msg_h->msg_type;

                recv_data_inf.monitoringDataHeaderLen = msg_h->len_mon_data_hdr;

                recv_data_inf.monitoringDataHeader = msg_h->len_mon_data_hdr ? msgbuf : NULL;

                gettimeofday(&recv_data_inf.arrival_time, NULL);

                recv_data_inf.firstPacketArrived = true;

                recv_data_inf.recvFragments = 1;

                recv_data_inf.priority = false;

                recv_data_inf.padding = false;

                recv_data_inf.confirmation = false;

                recv_data_inf.reliable = false;

                // send data recv callback to monitoring module

                (get_Recv_data_inf_cb) ((void *) &recv_data_inf);

        }

        // check the connection command type

        switch (con_msg->comand_type) {

                /*

                * if INVITE: enter a new socket make new entry in connect array

                * send an ok

                */

                case INVITE:

                        info("ML: received INVITE from %s (size:%d)\n", sock_id_str, msg_size);

                        /*

                        * check if another connection for the external connectionID exist

                        * that was established within the last 2 seconds

                        */

                        free_con_id = -1;

                        for (con_id = 0; con_id < CONNECTBUFSIZE; con_id++) {

                                if (connectbuf[con_id] != NULL) {

                                        if (mlCompareSocketIDs(&(connectbuf[con_id]->external_socketID), &(con_msg->sock_id)) == 0) {

                                                //timediff = difftime(now, connectbuf[con_id]->starttime);        //TODO: why this timeout? Shouldn't the connection be closed instead if there is a timeout?

                                                //if (timediff < 2)

                                                //update remote connection ID

                                                if (connectbuf[con_id]->external_connectionID != msg_h->local_con_id) {

                                                        warn("ML: updating remote connection ID for %s: from %d to %d\n",sock_id_str, connectbuf[con_id]->external_connectionID, msg_h->local_con_id);

                                                        connectbuf[con_id]->external_connectionID = msg_h->local_con_id;

                                                }

                                                break;

                                        }

                                } else if(free_con_id == -1)

                                        free_con_id = con_id;

                        }

                        if (con_id == CONNECTBUFSIZE) {

                                // create an entry in the connecttrybuf

                                if(free_con_id == -1) {

                                        error("ML: no new connect_buf available\n");

                                        return;

                                }

                                connectbuf[free_con_id] = (connect_data *) malloc(sizeof(connect_data));

                                memset(connectbuf[free_con_id],0,sizeof(connect_data));

                                connectbuf[free_con_id]->connection_head = connectbuf[free_con_id]->connection_last = NULL;

                                connectbuf[free_con_id]->starttime = time(NULL);

                                memcpy(&(connectbuf[free_con_id]->external_socketID), &(con_msg->sock_id), sizeof(socket_ID));

                                connectbuf[free_con_id]->pmtusize = con_msg->pmtu_size;        // bootstrap pmtu from the other's size. Not strictly needed, but a good hint

                                connectbuf[free_con_id]->timeout_event = NULL;

                                connectbuf[free_con_id]->external_connectionID = msg_h->local_con_id;

                                connectbuf[free_con_id]->internal_connect =

                                        !compare_external_address_socketIDs(&(con_msg->sock_id), loc_socketID);

                                con_id = free_con_id;

                        }

                        //if(connectbuf[con_id]->status <= CONNECT) { //TODO: anwer anyway. Why the outher would invite otherwise?

                                //update status and send back answer

                                connectbuf[con_id]->status = CONNECT;

                                send_conn_msg_with_pmtu_discovery(con_id, con_msg->pmtu_size, CONNECT);

                        //}

                        break;

                case CONNECT:

                        info("ML: received CONNECT from %s (size:%d)\n", sock_id_str, msg_size);

                        if(msg_h->remote_con_id != -1 && connectbuf[msg_h->remote_con_id] == NULL) {

                                error("ML: received CONNECT for inexistent connection rconID:%d\n",msg_h->remote_con_id);

                                return;

                        }

                        /*

                        * check if the connection status is not already 1 or 2

                        */

                        if (connectbuf[msg_h->remote_con_id]->status == INVITE) {

                                // set the external connectionID

                                connectbuf[msg_h->remote_con_id]->external_connectionID = msg_h->local_con_id;

                                // change status con_msg the connection_data

                                connectbuf[msg_h->remote_con_id]->status = READY;

                                // change pmtusize in the connection_data: not needed. receiving a CONNECT means our INVITE went through. So why change pmtu?

                                //connectbuf[msg_h->remote_con_id]->pmtusize = con_msg->pmtu_size;

                                // send the READY

                                send_conn_msg_with_pmtu_discovery(msg_h->remote_con_id, con_msg->pmtu_size, READY);

                                if (receive_Connection_cb != NULL)

                                        (receive_Connection_cb) (msg_h->remote_con_id, NULL);

                                // call all registered callbacks

                                while(connectbuf[msg_h->remote_con_id]->connection_head != NULL) {

                                        struct receive_connection_cb_list *temp;

                                        temp = connectbuf[msg_h->remote_con_id]->connection_head;

                                        (temp->connection_cb) (msg_h->remote_con_id, temp->arg);

                                        connectbuf[msg_h->remote_con_id]->connection_head = temp->next;

                                        free(temp);

                                }

                                connectbuf[msg_h->remote_con_id]->connection_head =

                                        connectbuf[msg_h->remote_con_id]->connection_last = NULL;

                        } else {

                                // send the READY

                                send_conn_msg_with_pmtu_discovery(msg_h->remote_con_id, con_msg->pmtu_size, READY);

                        }

                        debug("ML: active connection established\n");

                        break;

                        /*

                        * if READY: find the entry in the connection array set the

                        * connection active change the pmtu size

                        */

                case READY:

                        info("ML: received READY from %s (size:%d)\n", sock_id_str, msg_size);

                        if(connectbuf[msg_h->remote_con_id] == NULL) {

                                error("ML: received READY for inexistent connection\n");

                                return;

                        }

                        /*

                        * checks if the connection is not already established

                        */

                        if (connectbuf[msg_h->remote_con_id]->status == CONNECT) {

                                // change status of the connection

                                connectbuf[msg_h->remote_con_id]->status = READY;

                                // change pmtusize: not needed. pmtu doesn't have to be symmetric

                                //connectbuf[msg_h->remote_con_id]->pmtusize = con_msg->pmtu_size;

                                if (receive_Connection_cb != NULL)

                                        (receive_Connection_cb) (msg_h->remote_con_id, NULL);

                                while(connectbuf[msg_h->remote_con_id]->connection_head != NULL) {

                                        struct receive_connection_cb_list *temp;

                                        temp = connectbuf[msg_h->remote_con_id]->connection_head;

                                        (temp->connection_cb) (msg_h->remote_con_id, temp->arg);

                                        connectbuf[msg_h->remote_con_id]->connection_head = temp->next;

                                        free(temp);

                                }

                                connectbuf[msg_h->remote_con_id]->connection_head =

                                        connectbuf[msg_h->remote_con_id]->connection_last = NULL;

                                debug("ML: passive connection established\n");

                        }

                        break;

        }

}

void recv_stun_msg(char *msgbuf, int recvSize)

{

        /*

        * create empty stun message struct

        */

        StunMessage resp;

        memset(&resp, 0, sizeof(StunMessage));

        /*

        * parse the message

        */

        int returnValue = 0;

        returnValue = recv_stun_message(msgbuf, recvSize, &resp);

        if (returnValue == 0) {

                /*

                * read the reflexive Address into the local_socketID

                */

                struct sockaddr_in reflexiveAddr = {0};

                reflexiveAddr.sin_family = AF_INET;

                reflexiveAddr.sin_addr.s_addr = htonl(resp.mappedAddress.ipv4.addr);

                reflexiveAddr.sin_port = htons(resp.mappedAddress.ipv4.port);

                socketaddrgen reflexiveAddres = {0};

                reflexiveAddres.udpaddr = reflexiveAddr;

                local_socketID.external_addr = reflexiveAddres;

                NAT_traversal = true;

                // callback to the upper layer indicating that the socketID is now

                // ready to use

                (receive_SocketID_cb) (&local_socketID, 0);

        }

}

//done

void recv_timeout_cb(int fd, short event, void *arg)

{

        int recv_id = (long) arg;

        debug("ML: recv_timeout_cb called. Timeout for id:%d\n",recv_id);

        if (recvdatabuf[recv_id] == NULL) {

                return;

        }

/*        if(recvdatabuf[recv_id]->status == ACTIVE) {

                //TODO make timeout at least a DEFINE

                struct timeval timeout = { 4, 0 };

                recvdatabuf[recv_id]->status = INACTIVE;

                event_base_once(base, -1, EV_TIMEOUT, recv_timeout_cb,

                        arg, &timeout);

                return;

        }

*/

        if(recvdatabuf[recv_id]->status == ACTIVE) {

                // Monitoring layer hook

                if(get_Recv_data_inf_cb != NULL) {

                        mon_data_inf recv_data_inf;

                        recv_data_inf.remote_socketID =

                                        &(connectbuf[recvdatabuf[recv_id]->connectionID]->external_socketID);

                        recv_data_inf.buffer = recvdatabuf[recv_id]->recvbuf;

                        recv_data_inf.bufSize = recvdatabuf[recv_id]->bufsize;

                        recv_data_inf.msgtype = recvdatabuf[recv_id]->msgtype;

                        recv_data_inf.monitoringDataHeaderLen = recvdatabuf[recv_id]->monitoringDataHeaderLen;

                        recv_data_inf.monitoringDataHeader = recvdatabuf[recv_id]->monitoringDataHeaderLen ?

                                recvdatabuf[recv_id]->recvbuf : NULL;

                        gettimeofday(&recv_data_inf.arrival_time, NULL);

                        recv_data_inf.firstPacketArrived = recvdatabuf[recv_id]->firstPacketArrived;

                        recv_data_inf.recvFragments = recvdatabuf[recv_id]->recvFragments;

                        recv_data_inf.priority = false;

                        recv_data_inf.padding = false;

                        recv_data_inf.confirmation = false;

                        recv_data_inf.reliable = false;

                        // send data recv callback to monitoring module

                        (get_Recv_data_inf_cb) ((void *) &recv_data_inf);

                }

                // Get the right callback

                receive_data_cb receive_data_callback = recvcbbuf[recvdatabuf[recv_id]->msgtype];

                recv_params rParams;

                rParams.nrMissingBytes = recvdatabuf[recv_id]->bufsize - recvdatabuf[recv_id]->arrivedBytes;

                rParams.recvFragments = recvdatabuf[recv_id]->recvFragments;

                rParams.msgtype = recvdatabuf[recv_id]->msgtype;

                rParams.connectionID = recvdatabuf[recv_id]->connectionID;

                rParams.remote_socketID =

                        &(connectbuf[recvdatabuf[recv_id]->connectionID]->external_socketID);

                rParams.firstPacketArrived = recvdatabuf[recv_id]->firstPacketArrived;

                (receive_data_callback) (recvdatabuf[recv_id]->recvbuf + recvdatabuf[recv_id]->monitoringDataHeaderLen, recvdatabuf[recv_id]->bufsize - recvdatabuf[recv_id]->monitoringDataHeaderLen,

                        recvdatabuf[recv_id]->msgtype, &rParams);

                //clean up

                if (recvdatabuf[recv_id]->timeout_event) {

                        event_del(recvdatabuf[recv_id]->timeout_event);

                        event_free(recvdatabuf[recv_id]->timeout_event);

                        recvdatabuf[recv_id]->timeout_event = NULL;

                }

                free(recvdatabuf[recv_id]->recvbuf);

                free(recvdatabuf[recv_id]);

                recvdatabuf[recv_id] = NULL;

        }

}

// process a single recv data message

void recv_data_msg(struct msg_header *msg_h, char *msgbuf, int bufsize)

{

        debug("ML: received packet of size %d with rconID:%d lconID:%d type:%d offset:%d\n",bufsize,msg_h->remote_con_id,msg_h->local_con_id,msg_h->msg_type,msg_h->offset);

        int recv_id, free_recv_id = -1;

        if(connectbuf[msg_h->remote_con_id] == NULL) {

                debug("ML: Received a message not related to any opened connection!\n");

                return;

        }

        // check if a recv_data exist and enter data

        for (recv_id = 0; recv_id < RECVDATABUFSIZE; recv_id++)

                if (recvdatabuf[recv_id] != NULL) {

                        if (msg_h->remote_con_id == recvdatabuf[recv_id]->connectionID &&

                                        msg_h->msg_seq_num == recvdatabuf[recv_id]->seqnr)

                                                break;

                } else

                        if(free_recv_id == -1)

                                free_recv_id = recv_id;

        if(recv_id == RECVDATABUFSIZE) {

                //no recv_data found: create one

                recv_id = free_recv_id;

                recvdatabuf[recv_id] = (recvdata *) malloc(sizeof(recvdata));

                memset(recvdatabuf[recv_id], 0, sizeof(recvdata));

                recvdatabuf[recv_id]->connectionID = msg_h->remote_con_id;

                recvdatabuf[recv_id]->seqnr = msg_h->msg_seq_num;

                recvdatabuf[recv_id]->monitoringDataHeaderLen = msg_h->len_mon_data_hdr;

                recvdatabuf[recv_id]->bufsize = msg_h->msg_length + msg_h->len_mon_data_hdr;

                recvdatabuf[recv_id]->recvbuf = (char *) malloc(recvdatabuf[recv_id]->bufsize);

                recvdatabuf[recv_id]->arrivedBytes = 0;        //count this without the Mon headers

                /*

                * read the timeout data and set it

                */

                recvdatabuf[recv_id]->timeout_value = recv_timeout;

                recvdatabuf[recv_id]->timeout_event = NULL;

                recvdatabuf[recv_id]->recvID = recv_id;

                recvdatabuf[recv_id]->starttime = time(NULL);

                recvdatabuf[recv_id]->msgtype = msg_h->msg_type;

                // fill the buffer with zeros

                memset(recvdatabuf[recv_id]->recvbuf, 0, recvdatabuf[recv_id]->bufsize);

                debug(" new @ id:%d\n",recv_id);

        } else {        //message structure already exists, no need to create new

                debug(" found @ id:%d (arrived before this packet: bytes:%d fragments%d\n",recv_id, recvdatabuf[recv_id]->arrivedBytes, recvdatabuf[recv_id]->recvFragments);

        }

        //if first packet extract mon data header and advance pointer

        if (msg_h->offset == 0) {

                memcpy(recvdatabuf[recv_id]->recvbuf, msgbuf, msg_h->len_mon_data_hdr);

                msgbuf += msg_h->len_mon_data_hdr;

                bufsize -= msg_h->len_mon_data_hdr;

                recvdatabuf[recv_id]->firstPacketArrived = 1;

        }

        // increment fragmentnr

        recvdatabuf[recv_id]->recvFragments++;

        // increment the arrivedBytes

        recvdatabuf[recv_id]->arrivedBytes += bufsize;

        // enter the data into the buffer

        memcpy(recvdatabuf[recv_id]->recvbuf + msg_h->len_mon_data_hdr + msg_h->offset, msgbuf, bufsize);

        //TODO very basic checkif all fragments arrived: has to be reviewed

        if(recvdatabuf[recv_id]->arrivedBytes == recvdatabuf[recv_id]->bufsize - recvdatabuf[recv_id]->monitoringDataHeaderLen)

                recvdatabuf[recv_id]->status = COMPLETE; //buffer full -> msg completly arrived

        else

                recvdatabuf[recv_id]->status = ACTIVE;

        if (recv_data_callback) {

                if(recvdatabuf[recv_id]->status == COMPLETE) {

                        // Monitoring layer hook

                        if(get_Recv_data_inf_cb != NULL) {

                                mon_data_inf recv_data_inf;

                                recv_data_inf.remote_socketID =

                                         &(connectbuf[recvdatabuf[recv_id]->connectionID]->external_socketID);

                                recv_data_inf.buffer = recvdatabuf[recv_id]->recvbuf;

                                recv_data_inf.bufSize = recvdatabuf[recv_id]->bufsize;

                                recv_data_inf.msgtype = recvdatabuf[recv_id]->msgtype;

                                recv_data_inf.monitoringDataHeaderLen = recvdatabuf[recv_id]->monitoringDataHeaderLen;

                                recv_data_inf.monitoringDataHeader = recvdatabuf[recv_id]->monitoringDataHeaderLen ?

                                        recvdatabuf[recv_id]->recvbuf : NULL;

                                gettimeofday(&recv_data_inf.arrival_time, NULL);

                                recv_data_inf.firstPacketArrived = recvdatabuf[recv_id]->firstPacketArrived;

                                recv_data_inf.recvFragments = recvdatabuf[recv_id]->recvFragments;

                                recv_data_inf.priority = false;

                                recv_data_inf.padding = false;

                                recv_data_inf.confirmation = false;

                                recv_data_inf.reliable = false;

                                // send data recv callback to monitoring module

                                (get_Recv_data_inf_cb) ((void *) &recv_data_inf);

                        }

                        // Get the right callback

                        receive_data_cb receive_data_callback = recvcbbuf[msg_h->msg_type];

                        if (receive_data_callback) {

                                recv_params rParams;

                                rParams.nrMissingBytes = recvdatabuf[recv_id]->bufsize - recvdatabuf[recv_id]->monitoringDataHeaderLen - recvdatabuf[recv_id]->arrivedBytes;

                                rParams.recvFragments = recvdatabuf[recv_id]->recvFragments;

                                rParams.msgtype = recvdatabuf[recv_id]->msgtype;

                                rParams.connectionID = recvdatabuf[recv_id]->connectionID;

                                rParams.remote_socketID =

                                        &(connectbuf[recvdatabuf[recv_id]->connectionID]->external_socketID);

                                char str[1000];

                                mlSocketIDToString(rParams.remote_socketID,str,999);

                                debug("ML: received message from conID:%d, %s\n",recvdatabuf[recv_id]->connectionID,str);

                                rParams.firstPacketArrived = recvdatabuf[recv_id]->firstPacketArrived;

                                (receive_data_callback) (recvdatabuf[recv_id]->recvbuf + recvdatabuf[recv_id]->monitoringDataHeaderLen, recvdatabuf[recv_id]->bufsize - recvdatabuf[recv_id]->monitoringDataHeaderLen,

                                        recvdatabuf[recv_id]->msgtype, (void *) &rParams);

                        } else {

                            warn("ML: callback not initialized for this message type: %d!\n",msg_h->msg_type);

                        }

                        //clean up

                        if (recvdatabuf[recv_id]->timeout_event) {

                                debug("ML: freeing timeout for %d",recv_id);

                                event_del(recvdatabuf[recv_id]->timeout_event);

                                event_free(recvdatabuf[recv_id]->timeout_event);

                                recvdatabuf[recv_id]->timeout_event = NULL;

                        } else {

                                debug("ML: received in 1 packet\n",recv_id);

                        }

                        free(recvdatabuf[recv_id]->recvbuf);

                        free(recvdatabuf[recv_id]);

                        recvdatabuf[recv_id] = NULL;

                } else { // not COMPLETE

                        if (!recvdatabuf[recv_id]->timeout_event) {

                                //start time out

                                //TODO make timeout at least a DEFINE

                                recvdatabuf[recv_id]->timeout_event = event_new(base, -1, EV_TIMEOUT, &recv_timeout_cb, (void *) (long)recv_id);

                                evtimer_add(recvdatabuf[recv_id]->timeout_event, &recv_timeout);

                        }

                }

        }

}

//done

void pmtu_timeout_cb(int fd, short event, void *arg)

{

        int con_id = (long) arg;

        pmtu new_pmtusize;

        debug("ML: pmtu timeout called (lcon:%d)\n",con_id);

        if(connectbuf[con_id] == NULL) {

                error("ML: pmtu timeout called on non existing con_id\n");

                return;

        }

        if(connectbuf[con_id]->status == READY) {

                // nothing to do anymore

                event_del(connectbuf[con_id]->timeout_event);

                event_free(connectbuf[con_id]->timeout_event);

                connectbuf[con_id]->timeout_event = NULL;

                return;

        }

        info("ML: pmtu timeout while connecting(to:%s lcon:%d status:%d size:%d trial:%d tout:%ld.%06ld)\n",conid_to_string(con_id), con_id, connectbuf[con_id]->status, connectbuf[con_id]->pmtusize, connectbuf[con_id]->trials, connectbuf[con_id]->timeout_value.tv_sec, connectbuf[con_id]->timeout_value.tv_usec);

        if(connectbuf[con_id]->delay || connectbuf[con_id]->trials == MAX_TRIALS - 1) {

                double delay = connectbuf[con_id]->timeout_value.tv_sec + connectbuf[con_id]->timeout_value.tv_usec / 1000000.0;

                delay = delay * 2;

                info("\tML: increasing pmtu timeout to %f sec\n", delay);

                connectbuf[con_id]->timeout_value.tv_sec = floor(delay);

                connectbuf[con_id]->timeout_value.tv_usec = fmod(delay, 1.0) * 1000000.0;

                if(connectbuf[con_id]->delay) {

                        connectbuf[con_id]->delay = false;

                        reschedule_conn_msg(con_id);

                }

        }

        if(connectbuf[con_id]->trials == MAX_TRIALS) {

                // decrement the pmtu size

                struct timeval tout = PMTU_TIMEOUT;

                info("\tML: decreasing pmtu estimate from %d to %d\n", connectbuf[con_id]->pmtusize, pmtu_decrement(connectbuf[con_id]->pmtusize));

                connectbuf[con_id]->pmtusize = pmtu_decrement(connectbuf[con_id]->pmtusize);

                connectbuf[con_id]->timeout_value = tout; 

                connectbuf[con_id]->trials = 0;

        }

        //error in PMTU discovery?

        if (connectbuf[con_id]->pmtusize == ERROR) {

                if (connectbuf[con_id]->internal_connect == true) {

                        //as of now we tried directly connecting, now let's try trough the NAT

                        connectbuf[con_id]->internal_connect = false;

                        connectbuf[con_id]->pmtusize = MAX;

                } else {

                        //nothing to do we have to give up

                        error("ML: Could not create connection with connectionID %i!\n",con_id);

                        // envoke the callback for failed connection establishment

                        if(failed_Connection_cb != NULL)

                                (failed_Connection_cb) (con_id, NULL);

                        // delete the connection entry

                        mlCloseConnection(con_id);

                        return;

                }

        }

        //retry

        resend_conn_msg(con_id);

}

int schedule_pmtu_timeout(int con_id)

{

        if (! connectbuf[con_id]->timeout_event) {

                struct timeval tout = PMTU_TIMEOUT;

                connectbuf[con_id]->timeout_value = tout;

                connectbuf[con_id]->trials = 1;

                connectbuf[con_id]->timeout_event = event_new(base, -1, EV_TIMEOUT, &pmtu_timeout_cb, (void *) (long)con_id);

                evtimer_add(connectbuf[con_id]->timeout_event, &connectbuf[con_id]->timeout_value);

        }

}

/*

 * decrements the mtu size

 */

pmtu pmtu_decrement(pmtu pmtusize)

{

        pmtu pmtu_return_size;

        switch(pmtusize) {

        case MAX:

                return DSL;

        case DSL:

                return DSLMEDIUM;

        case DSLMEDIUM:

                return DSLSLIM;

        case DSLSLIM:

                return BELOWDSL;

        case BELOWDSL:

                return MIN;

        case MIN:

                return ERROR;

        default:

                warn("ML: strange pmtu size encountered:%d, changing to some safe value:%d\n", pmtusize, MIN);

                return MIN;

        }

}

// called when an ICMP pmtu error message (type 3, code 4) is received

void pmtu_error_cb_th(char *msg, int msglen)

{

        debug("ML: pmtu_error callback called msg_size: %d\n",msglen);

        //TODO debug

        return;

    char *msgbufptr = NULL;

    int msgtype;

    int connectionID;

    pmtu pmtusize;

    pmtu new_pmtusize;

    int dead = 0;

    // check the packettype

    msgbufptr = &msg[0];

    // check the msgtype

    msgbufptr = &msg[1];

    memcpy(&msgtype, msgbufptr, 4);

    if (msgtype == 0) {

        // get the connectionID

        msgbufptr = &msg[5];

        memcpy(&connectionID, msgbufptr, 4);

        int msgtype_c = connectbuf[connectionID]->status;

//        pmtusize = connectbuf[connectionID]->pmtutrysize;

        if (msgtype_c != msgtype) {

            dead = 1;

        }

    } else if (msgtype == 1) {

        // read the connectionID

        msgbufptr = &msg[9];

        memcpy(&connectionID, msgbufptr, 4);

        int msgtype_c = connectbuf[connectionID]->status;

//        pmtusize = connectbuf[connectionID]->pmtutrysize;

        if (msgtype_c != msgtype) {

            dead = 1;

        }

    }

    // decrement the pmtu size

    new_pmtusize = pmtu_decrement(pmtusize);

//    connectbuf[connectionID]->pmtutrysize = new_pmtusize;

    if (new_pmtusize == ERROR) {

                error("ML:  Could not create connection with connectionID %i !\n",

                        connectionID);

                if(failed_Connection_cb != NULL)

                        (failed_Connection_cb) (connectionID, NULL);

                // set the message type to a non existent message

                msgtype = 2;

                // delete the connection entry

                 mlCloseConnection(connectionID);

        }

    if (msgtype == 0 && dead != 1) {

        // stop the timeout event

        // timeout_del(connectbuf[connectionID]->timeout);

        /*

         * libevent2

         */

        // event_del(connectbuf[connectionID]->timeout);

        // create and send a connection message

//         create_conn_msg(new_pmtusize, connectionID,

//                         &local_socketID, INVITE);

//        send_conn_msg(connectionID, new_pmtusize);

        // set a timeout event for the pmtu discovery

        // timeout_set(connectbuf[connectionID]->timeout,pmtu_timeout_cb,(void

        // *)&connectionID);

        // timeout_add(connectbuf[connectionID]->timeout,&connectbuf[connectionID]->timeout_value);

        /*

         * libevent2

         */

        struct event *ev;

        ev = evtimer_new(base, pmtu_timeout_cb,

                         (void *) connectbuf[connectionID]);

        // connectbuf[connectionID]->timeout = ev;

        event_add(ev, &connectbuf[connectionID]->timeout_value);

    } else if (msgtype == 1 && dead != 1) {

        // stop the timeout event

        // timeout_del(connectbuf[connectionID]->timeout);

        /*

         * libevent2

         */

        // info("still here 11 \n");

        // printf("ev %d \n",connectbuf[connectionID]->timeout);

        // event_del(connectbuf[connectionID]->timeout );

        // evtimer_del(connectbuf[connectionID]->timeout );

//         // create and send a connection message

//         create_conn_msg(new_pmtusize,

//                         connectbuf[connectionID]->connectionID,

//                         NULL, CONNECT);

        //send_conn_msg(connectionID, new_pmtusize);

        // set a timeout event for the pmtu discovery

        // timeout_set(connectbuf[connectionID]->timeout,pmtu_timeout_cb,(void

        // *)&connectionID);

        // timeout_add(connectbuf[connectionID]->timeout,&connectbuf[connectionID]->timeout_value);

        /*

         * libevent2

         */

        // struct event *ev;

        // ev = evtimer_new(base,pmtu_timeout_cb, (void

        // *)connectbuf[connectionID]);

        // connectbuf[connectionID]->timeout = ev;

        // event_add(ev,&connectbuf[connectionID]->timeout_value);

    }

}

/*

 * what to do once a packet arrived if it is a conn packet send it to

 * recv_conn handler if it is a data packet send it to the recv_data

 * handler

 */

//done --

void recv_pkg(int fd, short event, void *arg)

{

        debug("ML: recv_pkg called\n");

        struct msg_header *msg_h;

        char msgbuf[MAX];

        pmtu recvSize = MAX;

        char *bufptr = msgbuf;

        int ttl;

        struct sockaddr_in recv_addr;

        int msg_size;

        recvPacket(fd, msgbuf, &recvSize, &recv_addr, pmtu_error_cb_th, &ttl);

        // check if it is not just an ERROR message

        if(recvSize < 0)

                return;

        // @TODO check if this simplistic STUN message recognition really always works, probably not

        unsigned short stun_bind_response = 0x0101;

        unsigned short * msgspot = (unsigned short *) msgbuf;

        if (*msgspot == stun_bind_response) {

                debug("ML: recv_pkg: parse stun message called\n");

                recv_stun_msg(msgbuf, recvSize);

                return;

        }

        msg_h = (struct msg_header *) msgbuf;

        //verify minimum size

        if (recvSize < sizeof(struct msg_header)) {

          info("UDP packet too small, can't be an ML packet");

          return;

        }

        //TODO add more verifications

        bufptr += MSG_HEADER_SIZE + msg_h->len_mon_packet_hdr;

        msg_size = recvSize - MSG_HEADER_SIZE - msg_h->len_mon_packet_hdr;

        //verify more fields

        if (msg_size < 0) {

          info("Corrupted UDP packet received");

          return;

        }

        if(get_Recv_pkt_inf_cb != NULL) {

                mon_pkt_inf msginfNow;

                msginfNow.monitoringHeaderLen = msg_h->len_mon_packet_hdr;

                msginfNow.monitoringHeader = msg_h->len_mon_packet_hdr ? &msgbuf[0] + MSG_HEADER_SIZE : NULL;

                //TODO rethink this ...

                if(msg_h->msg_type == ML_CON_MSG) {

                        struct conn_msg *c_msg = (struct conn_msg *) bufptr;

                        msginfNow.remote_socketID = &(c_msg->sock_id);

                }

                else if(connectbuf[msg_h->remote_con_id] == NULL) {

                        error("ML: received pkg called with non existent connection\n");

                        return;

                } else

                        msginfNow.remote_socketID = &(connectbuf[msg_h->remote_con_id]->external_socketID);

                msginfNow.buffer = bufptr;

                msginfNow.bufSize = recvSize;

                msginfNow.msgtype = msg_h->msg_type;

                msginfNow.ttl = ttl;

                msginfNow.dataID = msg_h->msg_seq_num;

                msginfNow.offset = msg_h->offset;

                msginfNow.datasize = msg_h->msg_length;

                gettimeofday(&msginfNow.arrival_time, NULL);

                (get_Recv_pkt_inf_cb) ((void *) &msginfNow);

        }

        switch(msg_h->msg_type) {

                case ML_CON_MSG:

                        debug("ML: received conn pkg\n");

                        recv_conn_msg(msg_h, bufptr, msg_size, &recv_addr);

                        break;

                default:

                        if(msg_h->msg_type < 127) {

                                debug("ML: received data pkg\n");

                                recv_data_msg(msg_h, bufptr, msg_size);

                                break;

                        }

                        debug("ML: unrecognised msg_type\n");

                        break;

        }

}

/*

 * compare the external IP address of two socketIDs

 */

int

compare_external_address_socketIDs(socketID_handle sock1, socketID_handle sock2)

{

        if( sock1->external_addr.udpaddr.sin_addr.s_addr == sock2->external_addr.udpaddr.sin_addr.s_addr)

                return 0;

        return 1;

}

void try_stun();

/*

 * the timeout of the NAT traversal

 */

void nat_traversal_timeout(int fd, short event, void *arg)

{

        if (NAT_traversal == false) {

                debug("ML: NAT traversal request re-send\n");

                if(receive_SocketID_cb)

                        (receive_SocketID_cb) (&local_socketID, 2);

                try_stun();

        }

}

//return IP address, or INADDR_NONE if can't resolve

unsigned long resolve(const char *ipaddr)

{

        struct hostent *h = gethostbyname(ipaddr);

        if (!h) {

                error("ML: Unable to resolve host name %s\n", ipaddr);

                return INADDR_NONE;

        }

        unsigned long *addr = (unsigned long *) (h->h_addr);

        return *addr;

}

/*

 * returns the file descriptor, or <0 on error. The ipaddr can be a null

 * pointer. Then all available ipaddr on the machine are choosen.

 */

int create_socket(const int port, const char *ipaddr)

{

        struct sockaddr_in udpaddr = {0};

        udpaddr.sin_family = AF_INET;

        if (ipaddr == NULL) {

                /*

                * try to guess the local IP address

                */

                const char *ipaddr_iface = mlAutodetectIPAddress();

                if (ipaddr_iface) {

                        udpaddr.sin_addr.s_addr = inet_addr(ipaddr_iface);

                } else {

                        udpaddr.sin_addr.s_addr = INADDR_ANY;

                }

        } else {

                udpaddr.sin_addr.s_addr = inet_addr(ipaddr);

        }

        udpaddr.sin_port = htons(port);

        socketaddrgen udpgen;

        memset(&udpgen,0,sizeof(socketaddrgen));        //this will be sent over the net, so set it to 0

        udpgen.udpaddr = udpaddr;

        local_socketID.internal_addr = udpgen;

        socketfd = createSocket(port, ipaddr);

        if (socketfd < 0){

                return socketfd;

        }

        struct event *ev;

        ev = event_new(base, socketfd, EV_READ | EV_PERSIST, recv_pkg, NULL);

        event_add(ev, NULL);

        try_stun();

        return socketfd;

}

/*

 * try to figure out external IP using STUN, if defined

 */

void try_stun()

{

        if (isStunDefined()) {

                /*

                * send the NAT traversal STUN request

                */

                 send_stun_request(socketfd, &stun_server);

                /*

                * enter a NAT traversal timeout that takes care of retransmission

                */

                struct event *ev1;

                struct timeval timeout_value_NAT_traversal = NAT_TRAVERSAL_TIMEOUT;

                ev1 = evtimer_new(base, nat_traversal_timeout, NULL);

                event_add(ev1, &timeout_value_NAT_traversal);

                NAT_traversal = false;

        } else {

                /*

                * Assume we have accessibility and copy internal address to external one

                */

                local_socketID.external_addr = local_socketID.internal_addr;

                NAT_traversal = true; // @TODO: this is not really NAT traversal, but a flag that init is over

                // callback to the upper layer indicating that the socketID is now

                // ready to use

                if(receive_SocketID_cb)

                        (receive_SocketID_cb) (&local_socketID, 0); //success

        }

}

/**************************** END OF INTERNAL ***********************/

/**************************** MONL functions *************************/

int mlInit(bool recv_data_cb,struct timeval timeout_value,const int port,const char *ipaddr,const int stun_port,const char *stun_ipaddr,receive_localsocketID_cb local_socketID_cb,void *arg){

        base = (struct event_base *) arg;

        recv_data_callback = recv_data_cb;

        mlSetRecvTimeout(timeout_value);

        if (stun_ipaddr) {

                 mlSetStunServer(stun_port, stun_ipaddr);

        } else {

        }

        register_recv_localsocketID_cb(local_socketID_cb);

        return create_socket(port, ipaddr);

}

/* register callbacks  */

void mlRegisterGetRecvPktInf(get_recv_pkt_inf_cb recv_pkt_inf_cb){

        if (recv_pkt_inf_cb == NULL)

                error("ML: Register get_recv_pkt_inf_cb failed: NULL ptr  \n");

        else

                get_Recv_pkt_inf_cb = recv_pkt_inf_cb;

}

void mlRegisterGetSendPktInf(get_send_pkt_inf_cb  send_pkt_inf_cb){

        if (send_pkt_inf_cb == NULL)

                error("ML: Register get_send_pkt_inf_cb: NULL ptr  \n");

        else

                get_Send_pkt_inf_cb = send_pkt_inf_cb;

}

void mlRegisterSetMonitoringHeaderPktCb(set_monitoring_header_pkt_cb monitoring_header_pkt_cb ){

        if (monitoring_header_pkt_cb == NULL)

                error("ML: Register set_monitoring_header_pkt_cb: NULL ptr  \n");

        else

                set_Monitoring_header_pkt_cb = monitoring_header_pkt_cb;