File content as of revision 3:5e31b4687aad:

/*
 MQTTClient.cpp - A simple client for MQTT.
  Nicholas O'Leary
  http://knolleary.net

  Ported to mbed by Zoltan Hudak <hudakz@outlook.com>
*/
#include "MQTTClient.h"
#include <string.h>
#include <time.h>

/**
 * @brief
 * @note
 * @param
 * @retval
 */
MQTTClient::MQTTClient(void) :
    _client(NULL),
    _stream(NULL)
{ }

/**
 * @brief
 * @note
 * @param
 * @retval
 */
MQTTClient::MQTTClient
(
    IpAddress&  ip,
    uint16_t    port,
    void        (*onMessage) (char*, uint8_t*, unsigned int),
    TcpClient&  client
) :
    _client(&client),
    _ip(ip),
    _domain(NULL),
    _port(port),
    _stream(NULL),
    _onMessage(onMessage)
{ }

/**
 * @brief
 * @note
 * @param
 * @retval
 */
MQTTClient::MQTTClient
(
    const char* domain,
    uint16_t    port,
    void        (*onMessage) (char*, uint8_t*, unsigned int),
    TcpClient&  client
) :
    _client(&client),
    _domain((char*)domain),
    _port(port),
    _stream(NULL),
    _onMessage(onMessage)
{ }

/**
 * @brief
 * @note
 * @param
 * @retval
 */
MQTTClient::MQTTClient
(
    IpAddress&  ip,
    uint16_t    port,
    void        (*onMessage) (char*, uint8_t*, unsigned int),
    TcpClient&  client,
    Stream&     stream
) :
    _client(&client),
    _ip(ip),
    _domain(NULL),
    _port(port),
    _stream(&stream),
    _onMessage(onMessage)
{ }

/**
 * @brief
 * @note
 * @param
 * @retval
 */
MQTTClient::MQTTClient
(
    const char* domain,
    uint16_t    port,
    void        (*onMessage) (char*, uint8_t*, unsigned int),
    TcpClient&  client,
    Stream&     stream
) :
    _client(&client),
    _domain((char*)domain),
    _port(port),
    _stream(&stream),
    _onMessage(onMessage)
{ }

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::connect(const char* id)
{
    return connect(id, NULL, NULL, 0, 0, 0, 0);
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::connect(const char* id, const char* user, const char* pass)
{
    return connect(id, user, pass, 0, 0, 0, 0);
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::connect(const char* id, const char* willTopic, uint8_t willQos, uint8_t willRetain, const char* willMessage)
{
    return connect(id, NULL, NULL, willTopic, willQos, willRetain, willMessage);
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::connect
(
    const char*   id,
    const char*   user,
    const char*   pass,
    const char*   willTopic,
    uint8_t       willQos,
    uint8_t       willRetain,
    const char*   willMessage
)
{
    if (!connected()) {
        int result = 0;

        if (_domain != NULL) {
            result = !_client->connect(this->_domain, this->_port);
        }
        else {
            result = _client->connect(this->_ip, this->_port);
        }

        if (result) {
            _nextMsgId = 1;

            uint8_t         d[9] = { 0x00, 0x06, 'M', 'Q', 'I', 's', 'd', 'p', MQTTPROTOCOLVERSION };

            // Leave room in the buffer for header and variable length field
            uint16_t        length = 5;
            unsigned int    j;
            for (j = 0; j < 9; j++) {
                _buffer[length++] = d[j];
            }

            uint8_t v;
            if (willTopic) {
                v = 0x06 | (willQos << 3) | (willRetain << 5);
            }
            else {
                v = 0x02;
            }

            if (user != NULL) {
                v = v | 0x80;

                if (pass != NULL) {
                    v = v | (0x80 >> 1);
                }
            }

            _buffer[length++] = v;

            _buffer[length++] = ((MQTT_KEEPALIVE) >> 8);
            _buffer[length++] = ((MQTT_KEEPALIVE) & 0xFF);
            length = _writeString(id, _buffer, length);
            if (willTopic) {
                length = _writeString(willTopic, _buffer, length);
                length = _writeString(willMessage, _buffer, length);
            }

            if (user != NULL) {
                length = _writeString(user, _buffer, length);
                if (pass != NULL) {
                    length = _writeString(pass, _buffer, length);
                }
            }

            _write(MQTTCONNECT, _buffer, length - 5);

            _lastInActivity = _lastOutActivity = time(NULL);

            while (!_client->available()) {
                unsigned long   t = time(NULL);
                if (t - _lastInActivity > MQTT_KEEPALIVE) {
                    _client->stop();
                    return false;
                }
            }

            uint8_t     llen;
            uint16_t    len = _readPacket(&llen);

            if (len == 4 && _buffer[3] == 0) {
                _lastInActivity = time(NULL);
                _pingOutstanding = false;
                return true;
            }
        }

        _client->stop();
    }

    return false;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
uint8_t MQTTClient::_readByte(void)
{
    while (!_client->available()) { }

    return _client->recv();
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
uint16_t MQTTClient::_readPacket(uint8_t* lengthLength)
{
    uint16_t    len = 0;
    _buffer[len++] = _readByte();

    bool        isPublish = (_buffer[0] & 0xF0) == MQTTPUBLISH;
    uint32_t    multiplier = 1;
    uint16_t    length = 0;
    uint8_t     digit = 0;
    uint16_t    skip = 0;
    uint8_t     start = 0;

    do {
        digit = _readByte();
        _buffer[len++] = digit;
        length += (digit & 127) * multiplier;
        multiplier *= 128;
    } while ((digit & 128) != 0);
    *lengthLength = len - 1;

    if (isPublish) {
        // Read in topic length to calculate bytes to skip over for Stream writing
        _buffer[len++] = _readByte();
        _buffer[len++] = _readByte();
        skip = (_buffer[*lengthLength + 1] << 8) + _buffer[*lengthLength + 2];
        start = 2;
        if (_buffer[0] & MQTTQOS1) {
            // skip message id
            skip += 2;
        }
    }

    for (uint16_t i = start; i < length; i++) {
        digit = _readByte();
        if (this->_stream) {
            if (isPublish && len -*lengthLength - 2 > skip) {
                this->_stream->putc(digit);
            }
        }

        if (len < MQTT_MAX_PACKET_SIZE) {
            _buffer[len] = digit;
        }

        len++;
    }

    if (!this->_stream && len > MQTT_MAX_PACKET_SIZE) {
        len = 0;    // This will cause the packet to be ignored.
    }

    return len;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::loop(void)
{
    if (connected()) {
        unsigned long   t = time(NULL);
        if ((t - _lastInActivity > MQTT_KEEPALIVE) || (t - _lastOutActivity > MQTT_KEEPALIVE)) {
            if (_pingOutstanding) {
                _client->stop();
                return false;
            }
            else {
                _buffer[0] = MQTTPINGREQ;
                _buffer[1] = 0;
                _client->send(_buffer, 2);
                _lastOutActivity = t;
                _lastInActivity = t;
                _pingOutstanding = true;
            }
        }

        if (_client->available()) {
            uint8_t     llen;
            uint16_t    len = _readPacket(&llen);
            uint16_t    msgId = 0;
            uint8_t*    payload;
            if (len > 0) {
                _lastInActivity = t;

                //printf("Here I am\r\n");
                uint8_t type = _buffer[0] & 0xF0;
                if (type == MQTTPUBLISH) {
                    if (_onMessage) {
                        uint16_t    tl = (_buffer[llen + 1] << 8) + _buffer[llen + 2];
                        char        topic[tl + 1];
                        for (uint16_t i = 0; i < tl; i++) {
                            topic[i] = _buffer[llen + 3 + i];
                        }

                        topic[tl] = 0;

                        // msgId only present for QOS>0
                        if ((_buffer[0] & 0x06) == MQTTQOS1) {
                            msgId = (_buffer[llen + 3 + tl] << 8) + _buffer[llen + 3 + tl + 1];
                            payload = _buffer + llen + 3 + tl + 2;
                            _onMessage(topic, payload, len - llen - 3 - tl - 2);

                            _buffer[0] = MQTTPUBACK;
                            _buffer[1] = 2;
                            _buffer[2] = (msgId >> 8);
                            _buffer[3] = (msgId & 0xFF);
                            _client->send(_buffer, 4);
                            _lastOutActivity = t;
                        }
                        else {
                            payload = _buffer + llen + 3 + tl;
                            _onMessage(topic, payload, len - llen - 3 - tl);
                        }
                    }
                }
                else
                if (type == MQTTPINGREQ) {
                    _buffer[0] = MQTTPINGRESP;
                    _buffer[1] = 0;
                    _client->send(_buffer, 2);
                }
                else
                if (type == MQTTPINGRESP) {
                    _pingOutstanding = false;
                }
            }
        }

        return true;
    }

    return false;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::publish(const char* topic, const char* payload)
{
    return publish(topic, (uint8_t*)payload, strlen(payload), false);
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::publish(const char* topic, uint8_t* payload, unsigned int plength)
{
    return publish(topic, payload, plength, false);
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::publish(const char* topic, uint8_t* payload, unsigned int plength, bool retained)
{
    if (connected()) {
        // Leave room in the buffer for header and variable length field
        uint16_t    length = 5;
        length = _writeString(topic, _buffer, length);

        uint16_t    i;
        for (i = 0; i < plength; i++) {
            _buffer[length++] = payload[i];
        }

        uint8_t header = MQTTPUBLISH;
        if (retained) {
            header |= 1;
        }

        return _write(header, _buffer, length - 5);
    }

    return false;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::_write(uint8_t header, uint8_t* buf, uint16_t length)
{
    uint8_t lenBuf[4];
    uint8_t llen = 0;
    uint8_t digit;
    uint8_t pos = 0;
    uint8_t rc;
    uint8_t len = length;
    do {
        digit = len % 128;
        len = len / 128;
        if (len > 0) {
            digit |= 0x80;
        }

        lenBuf[pos++] = digit;
        llen++;
    } while (len > 0);

    buf[4 - llen] = header;
    for (int i = 0; i < llen; i++) {
        buf[5 - llen + i] = lenBuf[i];
    }

    rc = _client->send(buf + (4 - llen), length + 1 + llen);

    _lastOutActivity = time(NULL);
    return(rc == 1 + llen + length);
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::subscribe(const char* topic)
{
    bool    result = subscribe(topic, 0);
    wait_ms(50);
    return result;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::subscribe(const char* topic, uint8_t qos)
{
    if (qos > 1)
        return false;

    if (connected()) {
        // Leave room in the buffer for header and variable length field
        uint16_t    length = 5;
        _nextMsgId++;
        if (_nextMsgId == 0) {
            _nextMsgId = 1;
        }

        _buffer[length++] = (_nextMsgId >> 8);
        _buffer[length++] = (_nextMsgId & 0xFF);
        length = _writeString(topic, _buffer, length);
        _buffer[length++] = qos;
        return _write(MQTTSUBSCRIBE | MQTTQOS1, _buffer, length - 5);
    }

    return false;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::unsubscribe(const char* topic)
{
    if (connected()) {
        uint16_t    length = 5;
        _nextMsgId++;
        if (_nextMsgId == 0) {
            _nextMsgId = 1;
        }

        _buffer[length++] = (_nextMsgId >> 8);
        _buffer[length++] = (_nextMsgId & 0xFF);
        length = _writeString(topic, _buffer, length);
        return _write(MQTTUNSUBSCRIBE | MQTTQOS1, _buffer, length - 5);
    }

    return false;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
void MQTTClient::disconnect(void)
{
    _buffer[0] = MQTTDISCONNECT;
    _buffer[1] = 0;
    _client->send(_buffer, 2);
    _client->stop();
    _lastInActivity = _lastOutActivity = time(NULL);
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
uint16_t MQTTClient::_writeString(const char* string, uint8_t* buf, uint16_t pos)
{
    char*       idp = (char*)string;
    uint16_t    i = 0;

    pos += 2;
    while (*idp) {
        buf[pos++] = *idp++;
        i++;
    }

    buf[pos - i - 2] = (i >> 8);
    buf[pos - i - 1] = (i & 0xFF);
    return pos;
}

/**
 * @brief
 * @note
 * @param
 * @retval
 */
bool MQTTClient::connected(void)
{
    bool    rc;
    if (_client == NULL) {
        rc = false;
    }
    else {
        rc = (int)_client->connected();
        if (!rc)
            _client->stop();
    }

    return rc;
}