qtsnmp.cpp

#include "qtsnmp.h"
#include <QObject>
#include <QThread>

//----[ Constructors/Destructors ]-----------------------------------------------------

SNMPSession::SNMPSession()
        : QObject()
{
}

/**
*   The constructor will initialize the SNMPSession object with the given values,
*   and will also bind the UDP socket to the specified socketPort.
*   This allows the socket to emit the readyRead signal on datagram arrival.
*/
SNMPSession::SNMPSession(const QString &agentAddress, qint16 agentPort, qint16 socketPort)
        : QObject()
{
    this->agentAddress = new QHostAddress(agentAddress);
    this->agentPort = agentPort;
    this->socketPort = socketPort;
    udpSocket.bind(socketPort);
}

SNMPSession::~SNMPSession()
{
    delete agentAddress;
}


//----[ Get/Set methods ]----------------------------------------------------------------


void SNMPSession::setAgentAddress(const QString &agentAddress)
{
    this->agentAddress = new QHostAddress(agentAddress);
}

void SNMPSession::setAgentPort(qint16 agentPort)
{
    this->agentPort = agentPort;
}

void SNMPSession::setSocketPort(qint16 socketPort)
{
    this->socketPort = socketPort;
}

QHostAddress * SNMPSession::getAgentAddress() const
{
    return agentAddress;
}
qint16 SNMPSession::getAgentPort() const
{
    return agentPort;
}

qint16 SNMPSession::getSocketPort() const
{
    return socketPort;
}


//----[ SNMP set-request/get-request methods ]-------------------------------------------------


/**
*   This method will send a SNMP set-request with the specified community string,
*   OID and integer value.
*   Returns 0 on success or one of the following error codes on failture :
*   1 -- Response message too large to transport
*   2 -- The name of the requested object was not found
*   3 -- A data type in the request did not match the data type in the SNMP agent
*   4 -- The SNMP manager attempted to set a read-only parameter
*   5 -- General Error (some error other than the ones listed above)
*   6 -- Timeout, no response from agent (5 seconds)
*/
int SNMPSession::sendSetRequest(const QString &communityStringParameter, const QString oidParameter, int value)
{
    QByteArray communityString = communityStringParameter.toLatin1();
    QByteArray oid = oidParameter.toLatin1();

    QByteArray datagram; // the datagram to send
    QByteArray receivedDatagram; // the received value
    const int errorIndex = 14 + communityString.size();

// include Value field
    int currentLength = 0;
    if(value > 256)
    {
        unsigned char secondByte = value;
        int firstByte = value >> 8;
        datagram.push_back(firstByte);
        datagram.push_back(secondByte);
        datagram.push_front(0x02);
        datagram.push_front(0x02);
        currentLength += 4;
    } else
    {
        datagram.push_front(value);
        datagram.push_front(0x01);
        datagram.push_front(0x02);
        currentLength += 3;
    }
	
    convertOIDAccordingToBER(oid);
	
// include Object Identifier field
    datagram.push_front(oid);
    datagram.push_front(oid.size());
    datagram.push_front(0x6);
    currentLength += oid.size();
    currentLength += 2;
	
// include Varbind field
    datagram.push_front(currentLength);
    datagram.push_front(0x30);
    currentLength += 2;
	
// include Varbind List field
    datagram.push_front(currentLength);
    datagram.push_front(0x30);
    currentLength += 2;
	
// include Error Index field
    datagram.push_front((char)0x0);
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include Error field
    datagram.push_front((char)0x0);
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include Request ID
    datagram.push_front((rand() % 100 + 1));
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include PDU field
    datagram.push_front(currentLength);
    datagram.push_front(0xA3);
    currentLength += 2;
	
// include Community string
    datagram.push_front(communityString);
    datagram.push_front(communityString.size());
    datagram.push_front(0x04);
    currentLength += communityString.size();
    currentLength += 2;
	
// include SNMP version
    datagram.push_front((char)0x0);
    datagram.push_front(0x01);
    datagram.push_front(0x02);
    currentLength += 3;
	
// finish the construction with the SNMP Message lenght and type code
    datagram.push_front(currentLength);
    datagram.push_front(0x30);

// sending
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
	
// Receive if there is an answer. Timeout after 5 seconds
    int timeoutTimer = 0;
    while(timeoutTimer <= 3000)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            receivedDatagram.resize(udpSocket.pendingDatagramSize());
            udpSocket.readDatagram(receivedDatagram.data(), receivedDatagram.size());

            decodeSNMP(receivedDatagram);
            return errorStatus();
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    // sending second try
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
    timeoutTimer = 0;
	
    while(timeoutTimer <= 3000)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            receivedDatagram.resize(udpSocket.pendingDatagramSize());
            udpSocket.readDatagram(receivedDatagram.data(), receivedDatagram.size());

            decodeSNMP(receivedDatagram);
            return errorStatus();
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    // sending third try
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
    timeoutTimer = 0;
	
    while(timeoutTimer <= 500)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            receivedDatagram.resize(udpSocket.pendingDatagramSize());
            udpSocket.readDatagram(receivedDatagram.data(), receivedDatagram.size());

            decodeSNMP(receivedDatagram);
            return errorStatus();
        }
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    return 6;
}


/**
*   This method will send a SNMP set-request with the specified community string,
*   OID and string value.
*   Returns 0 on success or one of the following error codes on failture :
*   1 -- Response message too large to transport
*   2 -- The name of the requested object was not found
*   3 -- A data type in the request did not match the data type in the SNMP agent
*   4 -- The SNMP manager attempted to set a read-only parameter
*   5 -- General Error (some error other than the ones listed above)
*   6 -- Timeout, no response from agent (5 seconds)
*/
int SNMPSession::sendSetRequest(const QString &communityStringParameter,
                       const QString oidParameter, const QString &valueParameter)
{
    QByteArray communityString = communityStringParameter.toLatin1();
    QByteArray oid = oidParameter.toLatin1();
    QByteArray value = valueParameter.toLatin1();

    QByteArray datagram; // the datagram to send
    QByteArray receivedDatagram; // the received value
    const int errorIndex = 14 + communityString.size();

    // check if the string is  Address
    bool isIPAddress = false;
    int dots = 0;
	
    for(int i=0;i<value.length();i++)
    {
        if(value.at(i) == '.')
            dots++;
    }
	
    if(dots == 3)
	{
		isIPAddress = true;
	}

// include Value field
    int currentLength = 0;
    if(isIPAddress)
    {
        QList<QByteArray> octets = value.split('.');
        for(int i=0;i<4;i++)
            datagram.push_back(octets[i].toInt());
        currentLength = 4;
        datagram.push_front(currentLength);
        datagram.push_front(0x40);
        currentLength += 2;
    } else
    {
        for(int i=0;i<value.size();i++)
        {
            datagram.push_back(value.at(i));
            currentLength++;
        }
		
        datagram.push_front(currentLength);
        datagram.push_front(0x04);
        currentLength += 2;
    }

    convertOIDAccordingToBER(oid);
	
// include Object Identifier field
    datagram.push_front(oid);
    currentLength += oid.size();
    datagram.push_front(oid.size());
    datagram.push_front(0x6);
    currentLength += 2;
	
// include Varbind field
    datagram.push_front(currentLength);
    datagram.push_front(0x30);
    currentLength += 2;
	
// include Varbind List field
    datagram.push_front(currentLength);
    datagram.push_front(0x30);
    currentLength += 2;
	
// include Error Index field
    datagram.push_front((char)0x0);
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include Error field
    datagram.push_front((char)0x0);
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include Request ID
    datagram.push_front((rand() % 100 + 1));
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include PDU field
    datagram.push_front(currentLength);
    datagram.push_front(0xA3);
    currentLength += 2;
	
// include Community string
    datagram.push_front(communityString);
    datagram.push_front(communityString.size());
    datagram.push_front(0x04);
    currentLength += communityString.size();
    currentLength += 2;
	
// include SNMP version
    datagram.push_front((char)0x0);
    datagram.push_front(0x01);
    datagram.push_front(0x02);
    currentLength += 3;
	
// finish the construction with the SNMP Message lenght and type code
    datagram.push_front(currentLength);
    datagram.push_front(0x30);

// sending
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
    int timeoutTimer = 0;
	
    while(timeoutTimer <= 3000)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            receivedDatagram.resize(udpSocket.pendingDatagramSize());
            udpSocket.readDatagram(receivedDatagram.data(), receivedDatagram.size());

            decodeSNMP(receivedDatagram);
            return errorStatus();
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    // sending second attempt
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
    timeoutTimer = 0;
	
    while(timeoutTimer <= 3000)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            receivedDatagram.resize(udpSocket.pendingDatagramSize());
            udpSocket.readDatagram(receivedDatagram.data(), receivedDatagram.size());

            decodeSNMP(receivedDatagram);
            return errorStatus();
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    // sending third attempt
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
    timeoutTimer = 0;
	
    while(timeoutTimer <= 500)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            receivedDatagram.resize(udpSocket.pendingDatagramSize());
            udpSocket.readDatagram(receivedDatagram.data(), receivedDatagram.size());

            decodeSNMP(receivedDatagram);
            return errorStatus();
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    return 6;
}

/**
*   This method will send a SNMP get-request with the specified community string and OID
*   and then place the received get-response value in the receivedValue variable.
*   Returns 0 on success or one of the following error codes on failture :
*   1 -- Response message too large to transport
*   2 -- The name of the requested object was not found
*   3 -- A data type in the request did not match the data type in the SNMP agent
*   4 -- The SNMP manager attempted to set a read-only parameter
*   5 -- General Error (some error other than the ones listed above)
*   6 -- Timeout, no response from agent (5 seconds)
*/
int SNMPSession::sendGetRequest(QString &receivedValue,
                                const QString &communityStringParameter, const QString &oidParameter)
{
    QByteArray communityString = communityStringParameter.toLatin1();
    QByteArray oid = oidParameter.toLatin1();

    QByteArray datagram; // the datagram to send
    QByteArray receivedDatagram; // the received datagram

// include Value field
    int currentLength = 2;
    datagram.push_front((char)0x0);
    datagram.push_front(0x05);

    convertOIDAccordingToBER(oid);
	
// include Object Identifier field
    datagram.push_front(oid);
    currentLength += oid.size();
    datagram.push_front(oid.size());
    datagram.push_front(0x6);
    currentLength += 2;
	
// include Varbind field
    datagram.push_front(currentLength);
    datagram.push_front(0x30);
    currentLength += 2;
	
// include Varbind List field
    datagram.push_front(currentLength);
    datagram.push_front(0x30);
    currentLength += 2;
	
// include Error Index field
    datagram.push_front((char)0x0);
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
// include Error field
    datagram.push_front((char)0x0);
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include Request ID
    datagram.push_front((rand() % 100 + 1));
    datagram.push_front(0x1);
    datagram.push_front(0x2);
    currentLength += 3;
	
// include PDU field
    datagram.push_front(currentLength);
    datagram.push_front(0xA0);
    currentLength += 2;
	
// include Community string
    datagram.push_front(communityString);
    datagram.push_front(communityString.size());
    datagram.push_front(0x04);
    currentLength += communityString.size();
    currentLength += 2;
	
// include SNMP version
    datagram.push_front((char)0x0);
    datagram.push_front(0x01);
    datagram.push_front(0x02);
    currentLength += 3;
	
// finish the construction with the SNMP Message lenght and type code
    datagram.push_front(currentLength);
    datagram.push_front(0x30);

// SEND IT !!!
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
	
// Receive it
    int result = 0;

    int timeoutTimer = 0;
    while(timeoutTimer <= 3000)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            return result = getValueFromGetResponse(receivedValue, receivedDatagram);
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    // sending second attempt
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
    timeoutTimer = 0;
	
    while(timeoutTimer <= 3000)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            return result = getValueFromGetResponse(receivedValue, receivedDatagram);
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    // sending third attempt
    udpSocket.writeDatagram(datagram, datagram.size(), *agentAddress, agentPort);
    timeoutTimer = 0;
	
    while(timeoutTimer <= 500)
    {
        if(udpSocket.hasPendingDatagrams())
        {
            return result = getValueFromGetResponse(receivedValue, receivedDatagram);
        }
		
        QThread::msleep(1);
        timeoutTimer++;
    }
	
    return 6;
}


//----[ Additional public methods ]-------------------------------------------------



//----[ Other private methods ]-----------------------------------------------------

int SNMPSession::buildInt(int numBytes, QByteArray dataPart)
{
    int total = 0;
    int swift = 0;

    for( int n = numBytes; n > 0; n --)
    {
       total += dataPart.at(n-1) & 0xff << swift;
       swift += 8;
    }
    return total;
}

bool SNMPSession::decodeSNMP( QByteArray data)
{
    int i = 0;
    while( i < data.length() )
    {
        struct tlv part;
        part.type = data.at(i++) & 0xff;
        part.len = data.at(i) & 0xff;
        if( part.len > 0x80 ) // long form
        {
            int numBytes = part.len & 0x7f;
            part.len = buildInt( numBytes, data.mid(++i));
            i+=numBytes;
        }
        else
            i++;
        part.value = data.mid(i,part.len);
        if( part.type == 0x02 || part.type == 0x04 || part.type  == 0x06 )
           i += part.len;
        snmpTlvParts.push_back(part);
    }
}

/**
*   This method will extract the value from the specified GetResponse datagram.
*   Returns 0 on success or one of the following error codes on failture :
*   1 -- Response message too large to transport
*   2 -- The name of the requested object was not found
*   3 -- A data type in the request did not match the data type in the SNMP agent
*   4 -- The SNMP manager attempted to set a read-only parameter
*   5 -- General Error (some error other than the ones listed above)
*   6 -- Timeout, no response from agent (5 seconds)
*/
int SNMPSession::getValueFromGetResponse(QString &receivedValue, QByteArray &receivedDatagram)
{

    receivedDatagram.resize(udpSocket.pendingDatagramSize());
    int len = udpSocket.readDatagram(receivedDatagram.data(), receivedDatagram.size());
    decodeSNMP(receivedDatagram);

    int valueType = snmpTlvParts[10].type;
    int valueLenght = snmpTlvParts[10].len;
    QByteArray data = snmpTlvParts[10].value;
	
    // if there is a problem, return the error code
    if( errorStatus() != 0)
	{
        return errorStatus();
	}
		
    // if it's integer
    if( valueType == 0x02)
    {
        receivedValue = QString::number(buildInt(valueLenght,snmpTlvParts[10].value));
        return 0;
    }
	
    // if it's an  IP address
    if( valueType == 0x40)
    {
        QString octet;
        for(int i = 0;i < valueLenght; i++){
            octet = QString::number((unsigned char)snmpTlvParts[10].value.at(i), 10);
            receivedValue.push_back(octet);
            receivedValue.push_back(".");
        }
		
        receivedValue.truncate(receivedValue.size()-1);
		
        return 0;
    }
	
   // if it's an octet string
   if( valueType == 0x04)
    {
        receivedValue = data;
        return 0;
    }
	
    return 6;
}


/**
*   This method will return the bytes of an integer bigger than 127,
*   according to the Basic Encoding Rules (BER).
*/
QByteArray SNMPSession::convertIntAccordingToBER(int valueToConvert)
{
    QByteArray convertedValue;
    QString binValue = QString::number(valueToConvert, 2);
	
    if(binValue.size()>14)
    {
        QString firstByte;
        QString secondByte;
        QString thirdByte;

        thirdByte = binValue.right(7);
        binValue.truncate(binValue.size()-7);
        secondByte = binValue.right(7);
            secondByte.push_front("1");
        binValue.truncate(binValue.size()-7);
        firstByte = binValue;
		
        while(firstByte.size()<7)
		{
			firstByte.push_front("0");
		}
        firstByte.push_front("1");

        convertedValue.push_front(thirdByte.toInt(NULL, 2));
        convertedValue.push_front(secondByte.toInt(NULL, 2));
        convertedValue.push_front(firstByte.toInt(NULL, 2));
    } else
    {
		QString secondByte;
		QString firstByte;
		secondByte = binValue.right(7);
		binValue.truncate(binValue.size()-7);
		firstByte = binValue;
		while(firstByte.size()<7)
		{
			firstByte.push_front("0");
		}
		
		firstByte.push_front("1");

		convertedValue.push_front(secondByte.toInt(NULL, 2));
		convertedValue.push_front(firstByte.toInt(NULL, 2));
    }
	
    return convertedValue;
}

/**
*   This method will convert a given OID according to the Basic Encoding Rules (BER).
*   It uses SNMPSession::convertIntAccordingToBER.
*/
void SNMPSession::convertOIDAccordingToBER(QByteArray &oid)
{
    QList<QByteArray> oidPartsList = oid.split('.');
    int currentValue = 0;
    int addedNumbers = 0;
    oidPartsList.removeFirst();
    oid[0] = 0x2B;
	
    for(int i = 1;i < oidPartsList.size();i++)
    {
        if((oidPartsList[i].size())>1)
        {
            QString tempValue;
            for(int j = 0;j<oidPartsList[i].size();j++)
            {
               tempValue.push_back(oidPartsList[i].at(j));
            }
            currentValue = tempValue.toInt(NULL, 10);
        } else
        {
            QString tempValue;
            tempValue = oidPartsList[i].at(0);
            currentValue = tempValue.toInt(NULL, 10);
        }
        if(currentValue<=127)
        {
            oid[i+addedNumbers] = currentValue;
        } else
        {
            QByteArray convertedValue = convertIntAccordingToBER(currentValue);
			
            if(convertedValue.size() == 2)
            {
                oid[i+addedNumbers] = convertedValue[0];
                oid[i+1+addedNumbers] = convertedValue[1];
                addedNumbers++;
            } else
            {
                oid[i+addedNumbers] = convertedValue[0];
                oid[i+1+addedNumbers] = convertedValue[1];
                oid[i+2+addedNumbers] = convertedValue[2];
                addedNumbers =+ 2;
            }

        }
    }
	
    oid.resize(oidPartsList.size()+addedNumbers);
}