/*******************************************************************************
 *
 * Copyright (c) 2013, 2014 Intel Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v20.html
 * The Eclipse Distribution License is available at
 *    http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    David Navarro, Intel Corporation - initial API and implementation
 *    domedambrosio - Please refer to git log
 *    Fabien Fleutot - Please refer to git log
 *    Simon Bernard - Please refer to git log
 *    Toby Jaffey - Please refer to git log
 *    Manuel Sangoi - Please refer to git log
 *    Julien Vermillard - Please refer to git log
 *    Bosch Software Innovations GmbH - Please refer to git log
 *    Pascal Rieux - Please refer to git log
 *    Scott Bertin, AMETEK, Inc. - Please refer to git log
 *
 *******************************************************************************/

/*
 Copyright (c) 2013, 2014 Intel Corporation

 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:

     * Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
     * Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.
     * Neither the name of Intel Corporation nor the names of its contributors
       may be used to endorse or promote products derived from this software
       without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 THE POSSIBILITY OF SUCH DAMAGE.

 David Navarro <david.navarro@intel.com>

*/

#include "internals.h"

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <limits.h>

#define MAX_LOCATION_LENGTH 10      // strlen("/rd/65534") + 1

#ifdef LWM2M_CLIENT_MODE

static int prv_getRegistrationQueryLength(lwm2m_context_t * contextP,
                                          lwm2m_server_t * server)
{
    int index;
    int res;
    uint8_t buffer[21];

    index = strlen(QUERY_STARTER QUERY_VERSION_FULL QUERY_DELIMITER QUERY_NAME);
    index += strlen(contextP->endpointName);

    if (NULL != contextP->msisdn)
    {
        index += strlen(QUERY_DELIMITER QUERY_SMS);
        index += strlen(contextP->msisdn);
    }

#ifdef LWM2M_VERSION_1_0
    switch (server->binding)
    {
    case BINDING_U:
        index += strlen("&b=U");
        break;
    case BINDING_UQ:
        index += strlen("&b=UQ");
        break;
    case BINDING_S:
        index += strlen("&b=S");
        break;
    case BINDING_SQ:
        index += strlen("&b=SQ");
        break;
    case BINDING_US:
        index += strlen("&b=US");
        break;
    case BINDING_UQS:
        index += strlen("&b=UQS");
        break;
    default:
        return 0;
    }
#else
    if ((server->binding & ~(BINDING_UNKNOWN|BINDING_Q)) != 0)
    {
        index += QUERY_DELIMITER_LEN + QUERY_BINDING_LEN;
        if ((server->binding & BINDING_U) != 0)
        {
            index += 1;
        }
        if ((server->binding & BINDING_T) != 0)
        {
            index += 1;
        }
        if ((server->binding & BINDING_S) != 0)
        {
            index += 1;
        }
        if ((server->binding & BINDING_N) != 0)
        {
            index += 1;
        }
    }
    if ((server->binding & BINDING_Q) != 0)
    {
        index += QUERY_DELIMITER_LEN + QUERY_QUEUE_MODE_LEN;
    }
#endif

    if (0 != server->lifetime)
    {
        index += strlen(QUERY_DELIMITER QUERY_LIFETIME);
        res = utils_intToText(server->lifetime, buffer, sizeof(buffer));
        if (res == 0) return 0;
        index += res;
    }

    return index + 1;
}

static int prv_getRegistrationQuery(lwm2m_context_t * contextP,
                                    lwm2m_server_t * server,
                                    char * buffer,
                                    size_t length)
{
    size_t index;
    int res;

    res = utils_stringCopy(buffer, length, QUERY_STARTER QUERY_VERSION_FULL QUERY_DELIMITER QUERY_NAME);
    if (res < 0) return 0;
    index = res;
    res = utils_stringCopy(buffer + index, length - index, contextP->endpointName);
    if (res < 0) return 0;
    index += res;

    if (NULL != contextP->msisdn)
    {
        res = utils_stringCopy(buffer + index, length - index, QUERY_DELIMITER QUERY_SMS);
        if (res < 0) return 0;
        index += res;
        res = utils_stringCopy(buffer + index, length - index, contextP->msisdn);
        if (res < 0) return 0;
        index += res;
    }

#ifdef LWM2M_VERSION_1_0
    switch (server->binding)
    {
    case BINDING_U:
        res = utils_stringCopy(buffer + index, length - index, "&b=U");
        break;
    case BINDING_UQ:
        res = utils_stringCopy(buffer + index, length - index, "&b=UQ");
        break;
    case BINDING_S:
        res = utils_stringCopy(buffer + index, length - index, "&b=S");
        break;
    case BINDING_SQ:
        res = utils_stringCopy(buffer + index, length - index, "&b=SQ");
        break;
    case BINDING_US:
        res = utils_stringCopy(buffer + index, length - index, "&b=US");
        break;
    case BINDING_UQS:
        res = utils_stringCopy(buffer + index, length - index, "&b=UQS");
        break;
    default:
        res = -1;
    }
    if (res < 0) return 0;
    index += res;
#else
    if ((server->binding & ~(BINDING_UNKNOWN|BINDING_Q)) != 0)
    {
        res = utils_stringCopy(buffer + index, length - index, QUERY_DELIMITER QUERY_BINDING);
        if (res < 0) return 0;
        index += res;
        if ((server->binding & BINDING_U) != 0)
        {
            if (index >= length) return 0;
            buffer[index++] = 'U';
        }
        if ((server->binding & BINDING_T) != 0)
        {
            if (index >= length) return 0;
            buffer[index++] = 'T';
        }
        if ((server->binding & BINDING_S) != 0)
        {
            if (index >= length) return 0;
            buffer[index++] = 'S';
        }
        if ((server->binding & BINDING_N) != 0)
        {
            if (index >= length) return 0;
            buffer[index++] = 'N';
        }
    }
    if ((server->binding & BINDING_Q) != 0)
    {
        res = utils_stringCopy(buffer + index, length - index, QUERY_DELIMITER QUERY_QUEUE_MODE);
        if (res < 0) return 0;
        index += res;
    }
#endif

    if (0 != server->lifetime)
    {
        res = utils_stringCopy(buffer + index, length - index, QUERY_DELIMITER QUERY_LIFETIME);
        if (res < 0) return 0;
        index += res;
        res = utils_intToText(server->lifetime, (uint8_t *)buffer + index, length - index);
        if (res == 0) return 0;
        index += res;
    }

    if(index < length)
    {
        buffer[index++] = '\0';
    }
    else
    {
        return 0;
    }

    return index;
}

#ifndef LWM2M_VERSION_1_0
static uint8_t prv_readUint(lwm2m_object_t *objP,
                            uint16_t instanceId,
                            uint16_t resourceId,
                            uint64_t *valueP)
{
    uint8_t result = COAP_NO_ERROR;
    int size = 1;
    lwm2m_data_t * dataP = lwm2m_data_new(size);
    if (dataP == NULL)
    {
        return COAP_500_INTERNAL_SERVER_ERROR;
    }
    dataP[0].id = resourceId;
    result = objP->readFunc(instanceId, &size, &dataP, NULL, objP);
    if (result == COAP_205_CONTENT)
    {
        if (lwm2m_data_decode_uint(dataP, valueP))
        {
            result = COAP_NO_ERROR;
        }
        else
        {
            result = COAP_400_BAD_REQUEST;
        }
    }
    lwm2m_data_free(size, dataP);
    return result;
}

static uint8_t prv_readBoolean(lwm2m_object_t *objP,
                               uint16_t instanceId,
                               uint16_t resourceId,
                               bool *valueP)
{
    uint8_t result = COAP_NO_ERROR;
    int size = 1;
    lwm2m_data_t * dataP = lwm2m_data_new(size);
    if (dataP == NULL)
    {
        return COAP_500_INTERNAL_SERVER_ERROR;
    }
    dataP[0].id = resourceId;
    result = objP->readFunc(instanceId, &size, &dataP, NULL, objP);
    if (result == COAP_205_CONTENT)
    {
        if (lwm2m_data_decode_bool(dataP, valueP))
        {
            result = COAP_NO_ERROR;
        }
        else
        {
            result = COAP_400_BAD_REQUEST;
        }
    }
    lwm2m_data_free(size, dataP);
    return result;
}

static uint8_t prv_getRegistrationOrder(lwm2m_server_t *targetP,
                                        lwm2m_object_t *serverObjP,
                                        bool *orderedP,
                                        uint64_t *orderP)
{
    uint64_t order;
    uint8_t result = prv_readUint(serverObjP,
                                  targetP->servObjInstID,
                                  LWM2M_SERVER_REG_ORDER_ID,
                                  &order);
    if (result == COAP_NO_ERROR)
    {
        if (orderedP)
        {
            *orderedP = true;
        }
        if (orderP)
        {
            *orderP = order;
        }
    }
    else if (result == COAP_404_NOT_FOUND)
    {
        result = COAP_NO_ERROR;
        if (orderedP)
        {
            *orderedP = false;
        }
    }
    return result;
}

static uint8_t prv_getRegistrationFailureBlocking(lwm2m_server_t *targetP,
                                                  lwm2m_object_t *serverObjP,
                                                  bool *blockingP)
{
    bool blocking;
    uint8_t result = prv_readBoolean(serverObjP,
                                     targetP->servObjInstID,
                                     LWM2M_SERVER_REG_FAIL_BLOCK_ID,
                                     &blocking);
    if (result == COAP_NO_ERROR)
    {
        if (blockingP)
        {
            *blockingP = blocking;
        }
    }
    else if (result == COAP_404_NOT_FOUND)
    {
        result = COAP_NO_ERROR;
        if (blockingP)
        {
            *blockingP = false;
        }
    }
    return result;
}

static uint8_t prv_getRegistrationAttemptLimit(lwm2m_server_t *targetP,
                                               lwm2m_object_t *serverObjP,
                                               uint8_t *attemptLimitP,
                                               uint64_t *attemptDelayP)
{
    uint64_t attemptLimit;
    uint64_t attemptDelay;
    uint8_t result = prv_readUint(serverObjP,
                                  targetP->servObjInstID,
                                  LWM2M_SERVER_COMM_RETRY_COUNT_ID,
                                  &attemptLimit);
    if (result == COAP_404_NOT_FOUND)
    {
        attemptLimit = 5;
        result = COAP_NO_ERROR;
    }
    if (result == COAP_NO_ERROR)
    {
        result = prv_readUint(serverObjP,
                              targetP->servObjInstID,
                              LWM2M_SERVER_COMM_RETRY_TIMER_ID,
                              &attemptDelay);
        if (result == COAP_404_NOT_FOUND)
        {
            attemptDelay = 60;
            result = COAP_NO_ERROR;
        }
        if (result == COAP_NO_ERROR)
        {
            if (attemptLimit > 254) /* Implementation limit */
            {
                attemptLimit = 254;
            }
            if (attemptLimitP)
            {
                *attemptLimitP = attemptLimit;
            }
            if (attemptDelayP)
            {
                *attemptDelayP = attemptDelay;
            }
        }
    }
    return result;
}

static uint8_t prv_getRegistrationSequenceLimit(lwm2m_server_t *targetP,
                                                lwm2m_object_t *serverObjP,
                                                uint8_t *sequenceLimitP,
                                                uint64_t *sequenceDelayP)
{
    uint64_t sequenceLimit;
    uint64_t sequenceDelay;
    uint8_t result = prv_readUint(serverObjP,
                                  targetP->servObjInstID,
                                  LWM2M_SERVER_SEQ_RETRY_COUNT_ID,
                                  &sequenceLimit);
    if (result == COAP_404_NOT_FOUND)
    {
        sequenceLimit = 1;
        result = COAP_NO_ERROR;
    }
    if (result == COAP_NO_ERROR)
    {
        result = prv_readUint(serverObjP,
                              targetP->servObjInstID,
                              LWM2M_SERVER_SEQ_DELAY_TIMER_ID,
                              &sequenceDelay);
        if (result == COAP_404_NOT_FOUND)
        {
            sequenceDelay = 86400;
            result = COAP_NO_ERROR;
        }
        if (result == COAP_NO_ERROR)
        {
            if (sequenceLimit > 254) /* Implementation limit */
            {
                sequenceLimit = 254;
            }
            if (sequenceLimitP)
            {
                *sequenceLimitP = sequenceLimit;
            }
            if (sequenceDelayP)
            {
                *sequenceDelayP = sequenceDelay;
            }
        }
    }
    return result;
}

static uint8_t prv_getBootstrapOnRegistrationFailure(lwm2m_server_t *targetP,
                                                     lwm2m_object_t *serverObjP,
                                                     bool *bootstrapP)
{
    bool bootstrap;
    uint8_t result = prv_readBoolean(serverObjP,
                                     targetP->servObjInstID,
                                     LWM2M_SERVER_REG_FAIL_BOOTSTRAP_ID,
                                     &bootstrap);
    if (result == COAP_NO_ERROR)
    {
        if (bootstrapP)
        {
            *bootstrapP = bootstrap;
        }
    }
    else if (result == COAP_404_NOT_FOUND)
    {
        result = COAP_NO_ERROR;
        if (bootstrapP)
        {
            *bootstrapP = true;
        }
    }
    return result;
}

static uint8_t prv_startRegistration(lwm2m_server_t* targetP,
                                     lwm2m_object_t* serverObjP)
{
    uint64_t delay;
    uint8_t result = prv_readUint(serverObjP,
                                  targetP->servObjInstID,
                                  LWM2M_SERVER_INITIAL_REG_DELAY_ID,
                                  &delay);
    if (result == COAP_404_NOT_FOUND)
    {
        delay = 0;
        result = COAP_NO_ERROR;
    }
    if (result == COAP_NO_ERROR)
    {
        targetP->registration = lwm2m_gettime() + delay;
        targetP->status = STATE_REG_HOLD_OFF;
    }

    return result;
}

static void prv_handleRegistrationSequenceFailure(lwm2m_context_t *contextP, lwm2m_object_t *serverObjP, lwm2m_server_t *targetP)
{
    bool ordered = false;
    bool blocking = false;
    uint8_t sequenceLimit;
    uint64_t sequenceDelay;
    uint8_t result = prv_getRegistrationOrder(targetP, serverObjP, &ordered, NULL);
    if (result == COAP_NO_ERROR && ordered)
    {
        result = prv_getRegistrationFailureBlocking(targetP, serverObjP, &blocking);
        if (result == COAP_NO_ERROR && !blocking && targetP->sequence == 1)
        {
            /* Find the next ordered registration to start */
            registration_start(contextP, false);
        }
    }

    result = prv_getRegistrationSequenceLimit(targetP, serverObjP, &sequenceLimit, &sequenceDelay);
    if (result == COAP_NO_ERROR)
    {
        if (targetP->sequence >= sequenceLimit)
        {
            bool bootstrap;
            targetP->status = STATE_REG_FAILED;
            LOG_ARG("%d Registration failed", targetP->shortID);

            result = prv_getBootstrapOnRegistrationFailure(targetP, serverObjP, &bootstrap);
            if (result != COAP_NO_ERROR || bootstrap)
            {
                contextP->state = STATE_BOOTSTRAP_REQUIRED;
            }
            else if(ordered && blocking)
            {
                /* Fail any other ordered registrations not yet started */
                for (targetP = contextP->serverList; targetP; targetP = targetP->next)
                {
                    if (targetP->status == STATE_DEREGISTERED)
                    {
                        if (prv_getRegistrationOrder(targetP, serverObjP, &ordered, NULL) == COAP_NO_ERROR
                            && ordered)
                        {
                            targetP->status = STATE_REG_FAILED;
                        }
                    }
                }
            }
        }
        else
        {
            targetP->registration = lwm2m_gettime() + sequenceDelay;
            targetP->status = STATE_REG_HOLD_OFF;
            targetP->attempt = 0;
            LOG_ARG("%d Registration sequence failed", targetP->shortID);
        }
    }
    else
    {
        targetP->status = STATE_REG_FAILED;
        LOG_ARG("%d Registration failed", targetP->shortID);
    }
}

static void prv_handleRegistrationAttemptFailure(lwm2m_context_t *contextP, lwm2m_server_t *targetP)
{
    lwm2m_object_t *serverObjP;

    serverObjP = (lwm2m_object_t*)LWM2M_LIST_FIND(contextP->objectList, LWM2M_SERVER_OBJECT_ID);
    if (serverObjP)
    {
        uint8_t attemptLimit;
        uint64_t attemptDelay;
        uint8_t result;

        result = prv_getRegistrationAttemptLimit(targetP, serverObjP, &attemptLimit, &attemptDelay);
        if (result == COAP_NO_ERROR)
        {
            if (targetP->attempt >= attemptLimit)
            {
                prv_handleRegistrationSequenceFailure(contextP, serverObjP, targetP);
            }
            else
            {
                targetP->registration = lwm2m_gettime() + attemptDelay * (1 << (targetP->attempt - 1));
                targetP->status = STATE_REG_HOLD_OFF;
                LOG_ARG("%d Registration attempt failed", targetP->shortID);
            }
        }
        else
        {
            targetP->status = STATE_REG_FAILED;
            LOG_ARG("%d Registration failed", targetP->shortID);
        }
    }
    else
    {
        targetP->status = STATE_REG_FAILED;
        LOG_ARG("%d Registration failed", targetP->shortID);
    }
}
#endif

static void prv_handleRegistrationReply(lwm2m_context_t * contextP,
                                        lwm2m_transaction_t * transacP,
                                        void * message)
{
    coap_packet_t * packet = (coap_packet_t *)message;
    lwm2m_server_t * targetP = (lwm2m_server_t *)(transacP->userData);

#ifdef LWM2M_VERSION_1_0
    (void)contextP; /* unused */
#endif

    if (targetP->status == STATE_REG_PENDING)
    {
        time_t tv_sec = lwm2m_gettime();
        if (tv_sec >= 0)
        {
            targetP->registration = tv_sec;
        }
        if (packet != NULL && packet->code == COAP_201_CREATED)
        {
            targetP->status = STATE_REGISTERED;
            if (NULL != targetP->location)
            {
                lwm2m_free(targetP->location);
            }
            targetP->location = coap_get_multi_option_as_string(packet->location_path);

            LOG_ARG("%d Registration successful", targetP->shortID);
#ifndef LWM2M_VERSION_1_0
            {
                lwm2m_object_t *serverObjP;

                serverObjP = (lwm2m_object_t*)LWM2M_LIST_FIND(contextP->objectList, LWM2M_SERVER_OBJECT_ID);
                if (serverObjP)
                {
                    bool ordered;
                    uint8_t result;

                    result = prv_getRegistrationOrder(targetP, serverObjP, &ordered, NULL);
                    if (result == COAP_NO_ERROR && ordered)
                    {
                        bool blocking;

                        if (1 == targetP->sequence)
                        {
                            /* Find the next ordered registration to start */
                            registration_start(contextP, false);
                        }
                        else
                        {
                            result = prv_getRegistrationFailureBlocking(targetP, serverObjP, &blocking);
                            if (result == COAP_NO_ERROR && !blocking)
                            {
                                /* Find the next ordered registration to start */
                                registration_start(contextP, false);
                            }
                        }
                    }
                }
            }
#endif
        }
        else
        {
#ifdef LWM2M_VERSION_1_0
            targetP->status = STATE_REG_FAILED;
            LOG_ARG("%d Registration failed", targetP->shortID);
#else
            prv_handleRegistrationAttemptFailure(contextP, targetP);
#endif
        }
    }
}

// send the registration for a single server
static uint8_t prv_register(lwm2m_context_t * contextP,
                            lwm2m_server_t * server)
{
    char * query;
    int query_length;
    uint8_t * payload;
    int payload_length;
    lwm2m_transaction_t * transaction;

    payload_length = object_getRegisterPayloadBufferLength(contextP);
    if(payload_length == 0) return COAP_500_INTERNAL_SERVER_ERROR;
    payload = lwm2m_malloc(payload_length);
    if(!payload) return COAP_500_INTERNAL_SERVER_ERROR;
    payload_length = object_getRegisterPayload(contextP, payload, payload_length);
    if(payload_length == 0)
    {
        lwm2m_free(payload);
        return COAP_500_INTERNAL_SERVER_ERROR;
    }

    query_length = prv_getRegistrationQueryLength(contextP, server);
    if(query_length == 0)
    {
        lwm2m_free(payload);
        return COAP_500_INTERNAL_SERVER_ERROR;
    }
    query = lwm2m_malloc(query_length);
    if(!query)
    {
        lwm2m_free(payload);
        return COAP_500_INTERNAL_SERVER_ERROR;
    }
    if(prv_getRegistrationQuery(contextP, server, query, query_length) != query_length)
    {
        lwm2m_free(payload);
        lwm2m_free(query);
        return COAP_500_INTERNAL_SERVER_ERROR;
    }

    if (server->sessionH == NULL)
    {
        server->sessionH = lwm2m_connect_server(server->secObjInstID, contextP->userData);
    }

    if (NULL == server->sessionH)
    {
        lwm2m_free(payload);
        lwm2m_free(query);
        return COAP_503_SERVICE_UNAVAILABLE;
    }

    transaction = transaction_new(server->sessionH, COAP_POST, NULL, NULL, contextP->nextMID++, 4, NULL);
    if (transaction == NULL)
    {
        lwm2m_free(payload);
        lwm2m_free(query);
        return COAP_503_SERVICE_UNAVAILABLE;
    }

    coap_set_header_uri_path(transaction->message, "/"URI_REGISTRATION_SEGMENT);
    coap_set_header_uri_query(transaction->message, query);
    coap_set_header_content_type(transaction->message, LWM2M_CONTENT_LINK);
    coap_set_payload(transaction->message, payload, payload_length);

    transaction->callback = prv_handleRegistrationReply;
    transaction->userData = (void *) server;

    contextP->transactionList = (lwm2m_transaction_t *)LWM2M_LIST_ADD(contextP->transactionList, transaction);
    if (transaction_send(contextP, transaction) != 0)
    {
        lwm2m_free(payload);
        lwm2m_free(query);
        return COAP_503_SERVICE_UNAVAILABLE;
    }

    lwm2m_free(payload);
    lwm2m_free(query);
#ifndef LWM2M_VERSION_1_0
    if (0 == server->attempt)
    {
        server->sequence++;
    }
    server->attempt++;
#endif
    server->status = STATE_REG_PENDING;

    return COAP_NO_ERROR;
}

static void prv_handleRegistrationUpdateReply(lwm2m_context_t * contextP,
                                              lwm2m_transaction_t * transacP,
                                              void * message)
{
    coap_packet_t * packet = (coap_packet_t *)message;
    lwm2m_server_t * targetP = (lwm2m_server_t *)(transacP->userData);

    (void)contextP; /* unused */

    if (targetP->status == STATE_REG_UPDATE_PENDING)
    {
        time_t tv_sec = lwm2m_gettime();
        if (tv_sec >= 0)
        {
            targetP->registration = tv_sec;
        }
        if (packet != NULL && packet->code == COAP_204_CHANGED)
        {
            targetP->status = STATE_REGISTERED;
            LOG_ARG("%d Registration update successful", targetP->shortID);
        }
        else
        {
            targetP->status = STATE_REG_FAILED;
            LOG_ARG("%d Registration update failed", targetP->shortID);
        }
    }
}

static int prv_updateRegistration(lwm2m_context_t * contextP,
                                  lwm2m_server_t * server,
                                  bool withObjects)
{
    lwm2m_transaction_t * transaction;
    uint8_t * payload = NULL;
    int payload_length;

    transaction = transaction_new(server->sessionH, COAP_POST, NULL, NULL, contextP->nextMID++, 4, NULL);
    if (transaction == NULL) return COAP_500_INTERNAL_SERVER_ERROR;

    coap_set_header_uri_path(transaction->message, server->location);

    if (withObjects == true)
    {
        payload_length = object_getRegisterPayloadBufferLength(contextP);
        if(payload_length == 0)
        {
            transaction_free(transaction);
            return COAP_500_INTERNAL_SERVER_ERROR;
        }

        payload = lwm2m_malloc(payload_length);
        if(!payload)
        {
            transaction_free(transaction);
            return COAP_500_INTERNAL_SERVER_ERROR;
        }

        payload_length = object_getRegisterPayload(contextP, payload, payload_length);
        if(payload_length == 0)
        {
            transaction_free(transaction);
            lwm2m_free(payload);
            return COAP_500_INTERNAL_SERVER_ERROR;
        }
        coap_set_payload(transaction->message, payload, payload_length);
    }

    transaction->callback = prv_handleRegistrationUpdateReply;
    transaction->userData = (void *) server;

    contextP->transactionList = (lwm2m_transaction_t *)LWM2M_LIST_ADD(contextP->transactionList, transaction);

    if (transaction_send(contextP, transaction) == 0)
    {
        server->status = STATE_REG_UPDATE_PENDING;
    }

    if (withObjects == true)
    {
        lwm2m_free(payload);
    }
    return COAP_NO_ERROR;
}

// update the registration of a given server
int lwm2m_update_registration(lwm2m_context_t * contextP,
                              uint16_t shortServerID,
                              bool withObjects)
{
    lwm2m_server_t * targetP;
    uint8_t result;

    LOG_ARG("State: %s, shortServerID: %d", STR_STATE(contextP->state), shortServerID);

    result = COAP_NO_ERROR;

    targetP = contextP->serverList;
    if (targetP == NULL)
    {
        if (object_getServers(contextP, false) == -1)
        {
            LOG("No server found");
            return COAP_404_NOT_FOUND;
        }
    }
    while (targetP != NULL && result == COAP_NO_ERROR)
    {
        if (shortServerID != 0)
        {
            if (targetP->shortID == shortServerID)
            {
                // found the server, trigger the update transaction
                if (targetP->status == STATE_REGISTERED
                 || targetP->status == STATE_REG_UPDATE_PENDING)
                {
                    if (withObjects == true)
                    {
                        targetP->status = STATE_REG_FULL_UPDATE_NEEDED;
                    }
                    else
                    {
                        targetP->status = STATE_REG_UPDATE_NEEDED;
                    }
                    return COAP_NO_ERROR;
                }
                else if ((targetP->status == STATE_REG_FULL_UPDATE_NEEDED)
                      || (targetP->status == STATE_REG_UPDATE_NEEDED))
                {
                    // if REG (FULL) UPDATE is already set, returns COAP_NO_ERROR
                    if (withObjects == true)
                    {
                        targetP->status = STATE_REG_FULL_UPDATE_NEEDED;
                    }
                    return COAP_NO_ERROR;
                }
                else
                {
                    return COAP_400_BAD_REQUEST;
                }
            }
        }
        else
        {
            if (targetP->status == STATE_REGISTERED
             || targetP->status == STATE_REG_UPDATE_PENDING)
            {
                if (withObjects == true)
                {
                    targetP->status = STATE_REG_FULL_UPDATE_NEEDED;
                }
                else
                {
                    targetP->status = STATE_REG_UPDATE_NEEDED;
                }
            }
        }
        targetP = targetP->next;
    }

    if (shortServerID != 0
     && targetP == NULL)
    {
        // no server found
        result = COAP_404_NOT_FOUND;
    }

    return result;
}

uint8_t registration_start(lwm2m_context_t * contextP, bool restartFailed)
{
    lwm2m_server_t * targetP;
    uint8_t result = COAP_NO_ERROR;
#ifndef LWM2M_VERSION_1_0
    lwm2m_object_t * serverObjP;
    lwm2m_server_t * firstOrdered = NULL;
    uint64_t firstOrder = 0;
#endif

    LOG_ARG("State: %s", STR_STATE(contextP->state));

#ifndef LWM2M_VERSION_1_0
    serverObjP = (lwm2m_object_t*)LWM2M_LIST_FIND(contextP->objectList, LWM2M_SERVER_OBJECT_ID);
    if (!serverObjP)
    {
        return COAP_500_INTERNAL_SERVER_ERROR;
    }
#endif

    targetP = contextP->serverList;
    while (targetP != NULL && result == COAP_NO_ERROR)
    {
        if (targetP->status == STATE_DEREGISTERED
         || (restartFailed && targetP->status == STATE_REG_FAILED))
        {
#ifndef LWM2M_VERSION_1_0
            bool ordered;
            uint64_t order;

            targetP->attempt = 0;
            targetP->sequence = 0;
            result = prv_getRegistrationOrder(targetP, serverObjP, &ordered, &order);
            if (result == COAP_NO_ERROR)
            {
                if (ordered)
                {
                    if (!firstOrdered || order < firstOrder)
                    {
                        firstOrder = order;
                        firstOrdered = targetP;
                    }
                }
                else
                {
                    result = prv_startRegistration(targetP, serverObjP);
                }
            }
#else
            result = prv_register(contextP, targetP);
#endif
        }
        targetP = targetP->next;
    }

#ifndef LWM2M_VERSION_1_0
    if (firstOrdered)
    {
        result = prv_startRegistration(firstOrdered, serverObjP);
    }
#endif

    return result;
}


/*
 * Returns STATE_REG_PENDING if at least one registration is still pending
 * Returns STATE_REGISTERED if no registration is pending and there is at least one server the client is registered to
 * Returns STATE_REG_FAILED if all registration failed.
 */
lwm2m_status_t registration_getStatus(lwm2m_context_t * contextP)
{
    lwm2m_server_t * targetP;
    lwm2m_status_t reg_status;

    LOG_ARG("State: %s", STR_STATE(contextP->state));

    targetP = contextP->serverList;
    reg_status = STATE_REG_FAILED;

    while (targetP != NULL)
    {
        LOG_ARG("%d status: %s", targetP->shortID, STR_STATUS(targetP->status));
        switch (targetP->status)
        {
            case STATE_REGISTERED:
            case STATE_REG_UPDATE_NEEDED:
            case STATE_REG_FULL_UPDATE_NEEDED:
            case STATE_REG_UPDATE_PENDING:
                if (reg_status == STATE_REG_FAILED)
                {
                    reg_status = STATE_REGISTERED;
                }
                break;

            case STATE_REG_HOLD_OFF:
            case STATE_REG_PENDING:
                reg_status = STATE_REG_PENDING;
                break;

            case STATE_REG_FAILED:
            case STATE_DEREG_PENDING:
            case STATE_DEREGISTERED:
            default:
                break;
        }
        LOG_ARG("reg_status: %s", STR_STATUS(reg_status));

        targetP = targetP->next;
    }

    return reg_status;
}

static void prv_handleDeregistrationReply(lwm2m_context_t * contextP,
                                          lwm2m_transaction_t * transacP,
                                          void * message)
{
    lwm2m_server_t * targetP;

    (void)contextP; /* unused */
    (void)message; /* unused */

    targetP = (lwm2m_server_t *)(transacP->userData);
    if (NULL != targetP)
    {
        if (targetP->status == STATE_DEREG_PENDING)
        {
            targetP->status = STATE_DEREGISTERED;
        }
    }
}

void registration_deregister(lwm2m_context_t * contextP,
                             lwm2m_server_t * serverP)
{
    lwm2m_transaction_t * transaction;

    LOG_ARG("State: %s, %d status: %s", STR_STATE(contextP->state), serverP->shortID, STR_STATUS(serverP->status));

    if (serverP->status == STATE_DEREGISTERED
     || serverP->status == STATE_REG_PENDING
     || serverP->status == STATE_DEREG_PENDING
     || serverP->status == STATE_REG_FAILED
     || serverP->location == NULL)
    {
        return;
    }

    transaction = transaction_new(serverP->sessionH, COAP_DELETE, NULL, NULL, contextP->nextMID++, 4, NULL);
    if (transaction == NULL) return;

    coap_set_header_uri_path(transaction->message, serverP->location);

    transaction->callback = prv_handleDeregistrationReply;
    transaction->userData = (void *) serverP;

    contextP->transactionList = (lwm2m_transaction_t *)LWM2M_LIST_ADD(contextP->transactionList, transaction);
    if (transaction_send(contextP, transaction) == 0)
    {
        serverP->status = STATE_DEREG_PENDING;
    }
}
#endif

#ifdef LWM2M_SERVER_MODE
static void prv_freeClientObjectList(lwm2m_client_object_t * objects)
{
    while (objects != NULL)
    {
        lwm2m_client_object_t * objP;

        while (objects->instanceList != NULL)
        {
            lwm2m_list_t * target;

            target = objects->instanceList;
            objects->instanceList = objects->instanceList->next;
            lwm2m_free(target);
        }

        objP = objects;
        objects = objects->next;
        lwm2m_free(objP);
    }
}

static int prv_getParameters(multi_option_t * query,
                             char ** nameP,
                             uint32_t * lifetimeP,
                             char ** msisdnP,
                             lwm2m_binding_t * bindingP,
                             lwm2m_version_t * versionP)
{
    *nameP = NULL;
    *lifetimeP = 0;
    *msisdnP = NULL;
    *bindingP = 0;
    *versionP = VERSION_MISSING;

    while (query != NULL)
    {
        if (lwm2m_strncmp((char *)query->data, QUERY_NAME, QUERY_NAME_LEN) == 0)
        {
            if (*nameP != NULL) goto error;
            if (query->len == QUERY_NAME_LEN) goto error;

            *nameP = (char *)lwm2m_malloc(query->len - QUERY_NAME_LEN + 1);
            if (*nameP != NULL)
            {
                memcpy(*nameP, query->data + QUERY_NAME_LEN, query->len - QUERY_NAME_LEN);
                (*nameP)[query->len - QUERY_NAME_LEN] = 0;
            }
        }
        else if (lwm2m_strncmp((char *)query->data, QUERY_SMS, QUERY_SMS_LEN) == 0)
        {
            if (*msisdnP != NULL) goto error;
            if (query->len == QUERY_SMS_LEN) goto error;

            *msisdnP = (char *)lwm2m_malloc(query->len - QUERY_SMS_LEN + 1);
            if (*msisdnP != NULL)
            {
                memcpy(*msisdnP, query->data + QUERY_SMS_LEN, query->len - QUERY_SMS_LEN);
                (*msisdnP)[query->len - QUERY_SMS_LEN] = 0;
            }
        }
        else if (lwm2m_strncmp((char *)query->data, QUERY_LIFETIME, QUERY_LIFETIME_LEN) == 0)
        {
            int i;

            if (*lifetimeP != 0) goto error;
            if (query->len == QUERY_LIFETIME_LEN) goto error;

            for (i = QUERY_LIFETIME_LEN ; i < query->len ; i++)
            {
                if (query->data[i] < '0' || query->data[i] > '9') goto error;
                *lifetimeP = (*lifetimeP * 10) + (query->data[i] - '0');
            }
        }
        else if (lwm2m_strncmp((char *)query->data, QUERY_VERSION, QUERY_VERSION_LEN) == 0)
        {
            if (*versionP != VERSION_MISSING) goto error;
            if (query->len == QUERY_VERSION_LEN) goto error;

            *versionP = utils_stringToVersion(query->data + QUERY_VERSION_LEN, query->len - QUERY_VERSION_LEN);
        }
        else if (lwm2m_strncmp((char *)query->data, QUERY_BINDING, QUERY_BINDING_LEN) == 0)
        {
#ifdef LWM2M_VERSION_1_0
            if (*bindingP != 0) goto error;
#else
            if ((*bindingP & ~BINDING_Q) != 0) goto error;
#endif
            if (query->len == QUERY_BINDING_LEN) goto error;

            *bindingP |= utils_stringToBinding(query->data + QUERY_BINDING_LEN, query->len - QUERY_BINDING_LEN);
        }
#ifndef LWM2M_VERSION_1_0
        else if (lwm2m_strncmp((char *)query->data, QUERY_QUEUE_MODE, QUERY_QUEUE_MODE_LEN) == 0)
        {
            if ((*bindingP & BINDING_Q) != 0) goto error;
            if (query->len != QUERY_BINDING_LEN) goto error;

            *bindingP |= BINDING_Q;
        }
#endif
        query = query->next;
    }

    if (*versionP == VERSION_1_0 &&
        (*bindingP & (BINDING_T|BINDING_N)) != 0)
    {
        /* These bindings aren't valid in LWM2M 1.0 */
        goto error;
    }

    return 0;

error:
    if (*nameP != NULL) lwm2m_free(*nameP);
    if (*msisdnP != NULL) lwm2m_free(*msisdnP);

    return -1;
}

static uint16_t prv_splitLinkAttribute(uint8_t * data,
                                       uint16_t length,
                                       uint16_t * keyStart,
                                       uint16_t * keyLength,
                                       uint16_t * valueStart,
                                       uint16_t * valueLength)
{
    uint16_t index;
    uint16_t end;

    index = 0;
    while (index < length && data[index] == ' ') index++;
    if (index == length) return 0;

    if (data[index] == REG_ATTR_SEPARATOR)
    {
        index++;
    }
    if (index == length) return 0;

    *keyStart = index;

    while (index < length && data[index] != REG_ATTR_EQUALS) index++;
    if (index == *keyStart || index == length) return 0;

    *keyLength = index - *keyStart;

    index++;
    while (index < length && data[index] == ' ') index++;
    if (index == length) return 0;

    *valueStart = index;

    while (index < length && data[index] != REG_ATTR_SEPARATOR) index++;
    end = index;

    index--;
    while (index > *valueStart && data[index] == ' ') index--;
    if (index == *valueStart) return 0;

    *valueLength = index - *valueStart + 1;

    return end;
}

static int prv_parseLinkAttributes(uint8_t * data,
                                   uint16_t length,
                                   lwm2m_media_type_t * format,
                                   char ** altPath)
{
    uint16_t index;
    uint16_t pathStart;
    uint16_t pathLength;
    bool isValid;

    isValid = false;

    // Expecting application/link-format (RFC6690)
    // leading space were removed before. Remove trailing spaces.
    while (length > 0 && data[length-1] == ' ') length--;

    // strip open tag
    if (length >= 2 && data[0] == REG_URI_START)
    {
        data += 1;
        length -= 1;
    }
    else
    {
        return 0;
    }

    pathStart = 0;
    index = length - 1;
    while (index > 0 && data[index] != REG_URI_END) index--;
    // link attributes are required
    if (index == 0 || index == length - 1) return 0;

    // If there is a preceding /, remove it
    if (data[pathStart] == '/')
    {
        pathStart += 1;
    }
    pathLength = index - pathStart;

    index++;
    if (index >= length || data[index] != REG_ATTR_SEPARATOR) return 0;
    index++;

    while (index < length)
    {
        uint16_t result;
        uint16_t keyStart;
        uint16_t keyLength;
        uint16_t valueStart;
        uint16_t valueLength;

        result = prv_splitLinkAttribute(data + index, length - index, &keyStart, &keyLength, &valueStart, &valueLength);
        if (result == 0) return 0;

        if (keyLength == REG_ATTR_TYPE_KEY_LEN
         && 0 == lwm2m_strncmp(REG_ATTR_TYPE_KEY, (char*)data + index + keyStart, keyLength))
        {
            if (isValid == true) return 0; // declared twice
            if (valueLength != REG_ATTR_TYPE_VALUE_LEN
             || 0 != lwm2m_strncmp(REG_ATTR_TYPE_VALUE, (char*)data + index + valueStart, valueLength))
            {
                return 0;
            }
            isValid = true;
        }
        else if (keyLength == REG_ATTR_CONTENT_KEY_LEN
              && 0 == lwm2m_strncmp(REG_ATTR_CONTENT_KEY, (char*)data + index + keyStart, keyLength))
        {
            if (*format != LWM2M_CONTENT_TLV) return 0; // declared twice
            if (valueLength == REG_ATTR_CONTENT_JSON_LEN
             && 0 == lwm2m_strncmp(REG_ATTR_CONTENT_JSON, (char*)data + index + valueStart, valueLength))
            {
                *format = LWM2M_CONTENT_JSON;
            }
#ifdef LWM2M_OLD_CONTENT_FORMAT_SUPPORT
            else if (valueLength == REG_ATTR_CONTENT_JSON_OLD_LEN
             && 0 == lwm2m_strncmp(REG_ATTR_CONTENT_JSON_OLD, (char*)data + index + valueStart, valueLength))
            {
                *format = LWM2M_CONTENT_JSON_OLD;
            }
#endif
            else if (valueLength == REG_ATTR_CONTENT_SENML_JSON_LEN
             && 0 == lwm2m_strncmp(REG_ATTR_CONTENT_SENML_JSON, (char*)data + index + valueStart, valueLength))
            {
                *format = LWM2M_CONTENT_SENML_JSON;
            }
            else
            {
                return 0;
            }
        }
        // else ignore this one

        index += result;
    }

    if (isValid == false) return 0;

    if (pathLength != 0)
    {
        *altPath = (char *)lwm2m_malloc(pathLength + 1);
        if (*altPath == NULL) return 0;
        memcpy(*altPath, data + pathStart, pathLength);
        (*altPath)[pathLength] = 0;
    }

    return 1;
}

static int prv_getId(uint8_t * data,
                     uint16_t length,
                     uint16_t * objId,
                     uint16_t * instanceId)
{
    int value;
    uint16_t limit;

    // Expecting application/link-format (RFC6690)
    // leading space were removed before. Remove trailing spaces.
    while (length > 0 && data[length-1] == ' ') length--;

    // strip open and close tags
    if (length >= 1 && data[0] == REG_URI_START && data[length-1] == REG_URI_END)
    {
        data += 1;
        length -= 2;
    }
    else
    {
        return 0;
    }

    // If there is a preceding /, remove it
    if (length >= 1 && data[0] == '/')
    {
        data += 1;
        length -= 1;
    }

    limit = 0;
    while (limit < length && data[limit] != '/') limit++;
    value = uri_getNumber(data, limit);
    if (value < 0 || value >= LWM2M_MAX_ID) return 0;
    *objId = value;

    if (limit < length)
    {
        limit += 1;
        data += limit;
        length -= limit;

        if (length > 0)
        {
            value = uri_getNumber(data, length);
            if (value >= 0 && value < LWM2M_MAX_ID)
            {
                *instanceId = value;
                return 2;
            }
            else
            {
                return 0;
            }
        }
    }

    return 1;
}

static lwm2m_client_object_t * prv_decodeRegisterPayload(uint8_t * payload,
                                                         uint16_t payloadLength,
                                                         lwm2m_media_type_t * format,
                                                         char ** altPath)
{
    uint16_t index;
    lwm2m_client_object_t * objList;
    bool linkAttrFound;

    *altPath = NULL;
    *format = LWM2M_CONTENT_TLV;
    objList = NULL;
    linkAttrFound = false;
    index = 0;

    while (index <= payloadLength)
    {
        uint16_t start;
        uint16_t length;
        int result;
        uint16_t id;
        uint16_t instance;

        while (index < payloadLength && payload[index] == ' ') index++;
        if (index == payloadLength) break;

        start = index;
        while (index < payloadLength && payload[index] != REG_DELIMITER) index++;
        length = index - start;

        result = prv_getId(payload + start, length, &id, &instance);
        if (result != 0)
        {
            lwm2m_client_object_t * objectP;

            objectP = (lwm2m_client_object_t *)lwm2m_list_find((lwm2m_list_t *)objList, id);
            if (objectP == NULL)
            {
                objectP = (lwm2m_client_object_t *)lwm2m_malloc(sizeof(lwm2m_client_object_t));
                if (objectP == NULL) goto error;
                memset(objectP, 0, sizeof(lwm2m_client_object_t));
                objectP->id = id;
                objList = (lwm2m_client_object_t *)LWM2M_LIST_ADD(objList, objectP);
            }
            if (result == 2)
            {
                lwm2m_list_t * instanceP;

                instanceP = lwm2m_list_find(objectP->instanceList, instance);
                if (instanceP == NULL)
                {
                    instanceP = (lwm2m_list_t *)lwm2m_malloc(sizeof(lwm2m_list_t));
                    if(instanceP == NULL) goto error;
                    memset(instanceP, 0, sizeof(lwm2m_list_t));
                    instanceP->id = instance;
                    objectP->instanceList = LWM2M_LIST_ADD(objectP->instanceList, instanceP);
                }
            }
        }
        else if (linkAttrFound == false)
        {
            result = prv_parseLinkAttributes(payload + start, length, format, altPath);
            if (result == 0) goto error;

            linkAttrFound = true;
        }
        else goto error;

        index++;
    }

    return objList;

error:
    if (*altPath != NULL)
    {
        lwm2m_free(*altPath);
        *altPath = NULL;
    }
    prv_freeClientObjectList(objList);

    return NULL;
}

static lwm2m_client_t * prv_getClientByName(lwm2m_context_t * contextP,
                                            char * name)
{
    lwm2m_client_t * targetP;

    targetP = contextP->clientList;
    while (targetP != NULL && strcmp(name, targetP->name) != 0)
    {
        targetP = targetP->next;
    }

    return targetP;
}

void registration_freeClient(lwm2m_client_t * clientP)
{
    LOG("Entering");
    if (clientP->name != NULL) lwm2m_free(clientP->name);
    if (clientP->msisdn != NULL) lwm2m_free(clientP->msisdn);
    if (clientP->altPath != NULL) lwm2m_free(clientP->altPath);
    prv_freeClientObjectList(clientP->objectList);
    while(clientP->observationList != NULL)
    {
        lwm2m_observation_t * targetP;

        targetP = clientP->observationList;
        clientP->observationList = clientP->observationList->next;
        lwm2m_free(targetP);
    }
    lwm2m_free(clientP);
}

static int prv_getLocationString(uint16_t id,
                                 char location[MAX_LOCATION_LENGTH])
{
    int index;
    int result;

    memset(location, 0, MAX_LOCATION_LENGTH);

    result = utils_stringCopy(location, MAX_LOCATION_LENGTH, "/"URI_REGISTRATION_SEGMENT"/");
    if (result < 0) return 0;
    index = result;

    result = utils_intToText(id, (uint8_t*)location + index, MAX_LOCATION_LENGTH - index);
    if (result == 0) return 0;

    return index + result;
}

uint8_t registration_handleRequest(lwm2m_context_t * contextP,
                                   lwm2m_uri_t * uriP,
                                   void * fromSessionH,
                                   coap_packet_t * message,
                                   coap_packet_t * response)
{
    uint8_t result;
    time_t tv_sec;

    LOG_URI(uriP);
    tv_sec = lwm2m_gettime();
    if (tv_sec < 0) return COAP_500_INTERNAL_SERVER_ERROR;

    switch(message->code)
    {
    case COAP_POST:
    {
        char * name = NULL;
        uint32_t lifetime;
        char * msisdn;
        char * altPath;
        lwm2m_version_t version;
        lwm2m_binding_t binding;
        lwm2m_client_object_t * objects;
        lwm2m_media_type_t format;
        lwm2m_client_t * clientP;
        char location[MAX_LOCATION_LENGTH];

        if (0 != prv_getParameters(message->uri_query, &name, &lifetime, &msisdn, &binding, &version))
        {
            return COAP_400_BAD_REQUEST;
        }
        if (message->content_type != (coap_content_type_t)LWM2M_CONTENT_LINK
         && message->content_type != (coap_content_type_t)LWM2M_CONTENT_TEXT)
        {
            return COAP_400_BAD_REQUEST;
        }

        objects = prv_decodeRegisterPayload(message->payload, message->payload_len, &format, &altPath);

        if (!LWM2M_URI_IS_SET_OBJECT(uriP))
        {
            // Register operation
            // Version is mandatory
            if (version == VERSION_MISSING)
            {
                if (name != NULL) lwm2m_free(name);
                if (msisdn != NULL) lwm2m_free(msisdn);
                return COAP_400_BAD_REQUEST;
            }
            // Endpoint client name is mandatory
            if (name == NULL)
            {
                if (msisdn != NULL) lwm2m_free(msisdn);
                return COAP_400_BAD_REQUEST;
            }
            // Object list is mandatory
            if (objects == NULL)
            {
                lwm2m_free(name);
                if (msisdn != NULL) lwm2m_free(msisdn);
                return COAP_400_BAD_REQUEST;
            }
            // Check for a supported version
            switch (version)
            {
            case VERSION_1_0:
#ifndef LWM2M_VERSION_1_0
            case VERSION_1_1:
#endif
                /* Supported version */
                break;
            default:
                lwm2m_free(name);
                if (msisdn != NULL) lwm2m_free(msisdn);
                return COAP_412_PRECONDITION_FAILED;
            }

            if (lifetime == 0)
            {
                lifetime = LWM2M_DEFAULT_LIFETIME;
            }

            clientP = prv_getClientByName(contextP, name);
            if (clientP != NULL)
            {
                // we reset this registration
                lwm2m_free(clientP->name);
                if (clientP->msisdn != NULL) lwm2m_free(clientP->msisdn);
                if (clientP->altPath != NULL) lwm2m_free(clientP->altPath);
                prv_freeClientObjectList(clientP->objectList);
                clientP->objectList = NULL;
            }
            else
            {
                clientP = (lwm2m_client_t *)lwm2m_malloc(sizeof(lwm2m_client_t));
                if (clientP == NULL)
                {
                    lwm2m_free(name);
                    lwm2m_free(altPath);
                    if (msisdn != NULL) lwm2m_free(msisdn);
                    prv_freeClientObjectList(objects);
                    return COAP_500_INTERNAL_SERVER_ERROR;
                }
                memset(clientP, 0, sizeof(lwm2m_client_t));
                clientP->internalID = lwm2m_list_newId((lwm2m_list_t *)contextP->clientList);
                contextP->clientList = (lwm2m_client_t *)LWM2M_LIST_ADD(contextP->clientList, clientP);
            }
            clientP->name = name;
            clientP->version = version;
            clientP->binding = binding;
            clientP->msisdn = msisdn;
            clientP->altPath = altPath;
            clientP->format = format;
            clientP->lifetime = lifetime;
            clientP->endOfLife = tv_sec + lifetime;
            clientP->objectList = objects;
            clientP->sessionH = fromSessionH;

            if (prv_getLocationString(clientP->internalID, location) == 0)
            {
                registration_freeClient(clientP);
                return COAP_500_INTERNAL_SERVER_ERROR;
            }
            if (coap_set_header_location_path(response, location) == 0)
            {
                registration_freeClient(clientP);
                return COAP_500_INTERNAL_SERVER_ERROR;
            }

            if (contextP->monitorCallback != NULL)
            {
                contextP->monitorCallback(clientP->internalID, NULL, COAP_201_CREATED, LWM2M_CONTENT_TEXT, NULL, 0, contextP->monitorUserData);
            }
            result = COAP_201_CREATED;
        }
        else
        {
            // Registration update
            if (LWM2M_URI_IS_SET_INSTANCE(uriP)) return COAP_400_BAD_REQUEST;

            clientP = (lwm2m_client_t *)lwm2m_list_find((lwm2m_list_t *)contextP->clientList, uriP->objectId);
            if (clientP == NULL) return COAP_404_NOT_FOUND;

            // Endpoint client name MUST NOT be present
            if (name != NULL)
            {
                lwm2m_free(name);
                if (msisdn != NULL) lwm2m_free(msisdn);
                return COAP_400_BAD_REQUEST;
            }

            if (binding != BINDING_UNKNOWN)
            {
                clientP->binding = binding;
            }
            if (msisdn != NULL)
            {
                if (clientP->msisdn != NULL) lwm2m_free(clientP->msisdn);
                clientP->msisdn = msisdn;
            }
            if (lifetime != 0)
            {
                clientP->lifetime = lifetime;
            }
            // client IP address, port or MSISDN may have changed
            clientP->sessionH = fromSessionH;

            if (objects != NULL)
            {
                lwm2m_observation_t * observationP;

                // remove observations on object/instance no longer existing
                observationP = clientP->observationList;
                while (observationP != NULL)
                {
                    lwm2m_client_object_t * objP;
                    lwm2m_observation_t * nextP;

                    nextP = observationP->next;

                    objP = (lwm2m_client_object_t *)lwm2m_list_find((lwm2m_list_t *)objects, observationP->uri.objectId);
                    if (objP == NULL)
                    {
                        observationP->callback(clientP->internalID,
                                               &observationP->uri,
                                               COAP_202_DELETED,
                                               LWM2M_CONTENT_TEXT, NULL, 0,
                                               observationP->userData);
                        observe_remove(observationP);
                    }
                    else
                    {
                        if (LWM2M_URI_IS_SET_INSTANCE(&observationP->uri))
                        {
                            if (lwm2m_list_find((lwm2m_list_t *)objP->instanceList, observationP->uri.instanceId) == NULL)
                            {
                                observationP->callback(clientP->internalID,
                                                       &observationP->uri,
                                                       COAP_202_DELETED,
                                                       LWM2M_CONTENT_TEXT, NULL, 0,
                                                       observationP->userData);
                                observe_remove(observationP);
                            }
                        }
                    }

                    observationP = nextP;
                }

                prv_freeClientObjectList(clientP->objectList);
                clientP->objectList = objects;
            }

            clientP->endOfLife = tv_sec + clientP->lifetime;

            if (contextP->monitorCallback != NULL)
            {
                contextP->monitorCallback(clientP->internalID, NULL, COAP_204_CHANGED, LWM2M_CONTENT_TEXT, NULL, 0, contextP->monitorUserData);
            }
            result = COAP_204_CHANGED;
        }
    }
    break;

    case COAP_DELETE:
    {
        lwm2m_client_t * clientP;

        if (!LWM2M_URI_IS_SET_OBJECT(uriP)) return COAP_400_BAD_REQUEST;
        if (LWM2M_URI_IS_SET_INSTANCE(uriP)) return COAP_400_BAD_REQUEST;

        contextP->clientList = (lwm2m_client_t *)LWM2M_LIST_RM(contextP->clientList, uriP->objectId, &clientP);
        if (clientP == NULL) return COAP_400_BAD_REQUEST;
        if (contextP->monitorCallback != NULL)
        {
            contextP->monitorCallback(clientP->internalID, NULL, COAP_202_DELETED, LWM2M_CONTENT_TEXT, NULL, 0, contextP->monitorUserData);
        }
        registration_freeClient(clientP);
        result = COAP_202_DELETED;
    }
    break;

    default:
        return COAP_400_BAD_REQUEST;
    }

    return result;
}

void lwm2m_set_monitoring_callback(lwm2m_context_t * contextP,
                                   lwm2m_result_callback_t callback,
                                   void * userData)
{
    LOG("Entering");
    contextP->monitorCallback = callback;
    contextP->monitorUserData = userData;
}
#endif

// for each server update the registration if needed
// for each client check if the registration expired
void registration_step(lwm2m_context_t * contextP,
                       time_t currentTime,
                       time_t * timeoutP)
{
#ifdef LWM2M_CLIENT_MODE
    lwm2m_server_t * targetP = contextP->serverList;

    LOG_ARG("State: %s", STR_STATE(contextP->state));

    while (targetP != NULL)
    {
        switch (targetP->status)
        {
#ifndef LWM2M_VERSION_1_0
        case STATE_REG_HOLD_OFF:
        {
            time_t interval = targetP->registration - currentTime;
            if (0 >= interval)
            {
                prv_register(contextP, targetP);
            }
            else if (interval <= *timeoutP)
            {
                *timeoutP = interval;
            }
            break;
        }
#endif
        case STATE_REGISTERED:
        {
            time_t nextUpdate;
            time_t interval;

            nextUpdate = targetP->lifetime;
            if (COAP_MAX_TRANSMIT_WAIT < nextUpdate)
            {
                nextUpdate -= COAP_MAX_TRANSMIT_WAIT;
            }
            else
            {
                nextUpdate = nextUpdate >> 1;
            }

            interval = targetP->registration + nextUpdate - currentTime;
            if (0 >= interval)
            {
                LOG_ARG("%d Updating registration", targetP->shortID);
                prv_updateRegistration(contextP, targetP, false);
            }
            else if (interval < *timeoutP)
            {
                *timeoutP = interval;
            }
        }
        break;

        case STATE_REG_UPDATE_NEEDED:
            prv_updateRegistration(contextP, targetP, false);
            break;

        case STATE_REG_FULL_UPDATE_NEEDED:
            prv_updateRegistration(contextP, targetP, true);
            break;

        case STATE_REG_FAILED:
            if (targetP->sessionH != NULL)
            {
                lwm2m_close_connection(targetP->sessionH, contextP->userData);
                targetP->sessionH = NULL;
            }
            break;

        default:
            break;
        }
        targetP = targetP->next;
    }

#endif
#ifdef LWM2M_SERVER_MODE
    lwm2m_client_t * clientP;

    LOG("Entering");
    // monitor clients lifetime
    clientP = contextP->clientList;
    while (clientP != NULL)
    {
        lwm2m_client_t * nextP = clientP->next;

        if (clientP->endOfLife <= currentTime)
        {
            contextP->clientList = (lwm2m_client_t *)LWM2M_LIST_RM(contextP->clientList, clientP->internalID, NULL);
            if (contextP->monitorCallback != NULL)
            {
                contextP->monitorCallback(clientP->internalID, NULL, COAP_202_DELETED, LWM2M_CONTENT_TEXT, NULL, 0, contextP->monitorUserData);
            }
            registration_freeClient(clientP);
        }
        else
        {
            time_t interval;

            interval = clientP->endOfLife - currentTime;

            if (*timeoutP > interval)
            {
                *timeoutP = interval;
            }
        }
        clientP = nextP;
    }
#endif

}

