harbour-seaprint/src/ippdiscovery.cpp

#include "ippdiscovery.h"
#define A 1
#define PTR 12
#define TXT 16
#define AAAA 28
#define SRV 33

void put_addr(Bytestream& bts, QStringList addr)
{
    for(int i = 0; i < addr.length(); i++)
    {
        QString elem = addr[i];
        bts << (quint8)elem.size() << elem.toStdString();
    }
    bts << (quint8)0;
}

QStringList get_addr(Bytestream& bts)
{
    QStringList addr;
    while(true)
    {
        if(bts.nextU8(0))
        {
            break;
        }
        else if ((bts.peekU8()&0xc0)==0xc0)
        {
            quint16 ref = bts.getU16() & 0x0fff;
            Bytestream tmp = bts;
            tmp.setPos(ref);
            addr += get_addr(tmp);
            break;
        }
        else
        {
            std::string elem;
            bts/bts.getU8() >> elem;
            addr.append(QString(elem.c_str()));
        }
    }
    return addr;
}

IppDiscovery::IppDiscovery() : QStringListModel()
{
    socket = new QUdpSocket(this);
    connect(socket, SIGNAL(readyRead()),
            this, SLOT(readPendingDatagrams()));
    connect(this, SIGNAL(favouritesChanged()),
            this, SLOT(update()));
}

IppDiscovery::~IppDiscovery() {
    delete socket;
}


void IppDiscovery::discover() {

    Bytestream query;
    quint16 transactionid = 0;
    quint16 flags = 0;
    quint16 questions = 1;

    query << transactionid << flags << questions << (quint16)0 << (quint16)0 << (quint16)0;
    put_addr(query, {"_ipp","_tcp","local"});
    query << (quint16)0x000C << (quint16)0x0001;

    QByteArray bytes((char*)(query.raw()), query.size());
    socket->writeDatagram(bytes, QHostAddress("224.0.0.251"), 5353);

}

void IppDiscovery::update()
{
    qDebug() << _favourites << _found;
    this->setStringList(_favourites+_found);
}

void IppDiscovery::readPendingDatagrams()
{
    while (socket->hasPendingDatagrams()) {

        size_t size = socket->pendingDatagramSize();
        Bytestream resp(size);
        QHostAddress sender;
        quint16 senderPort;

        QMap<QString,QString> ptrs;
        QMap<QString,QString> rps;
        QMap<QString,quint16> ports;
        QMap<QString,QString> targets;
        QMultiMap<QString,QString> AAs;
        QMultiMap<QString,QString> AAAAs;

        socket->readDatagram((char*)(resp.raw()), size, &sender, &senderPort);
        sender = QHostAddress(sender.toIPv4Address());

        quint16 transactionid, flags, questions, answerRRs, authRRs, addRRs;
        resp >> transactionid >> flags >> questions >> answerRRs >> authRRs >> addRRs;

        for(quint16 i = 0; i < questions; i++)
        {
            quint16 qtype, qflags;
            QString qaddr = get_addr(resp).join('.');
            resp >> qtype >> qflags;
        }

        for(quint16 i = 0; i < answerRRs; i++)
        {
            quint16 atype, aflags, len;
            quint32 ttl;

            QString aaddr = get_addr(resp).join('.');
            resp >> atype >> aflags >> ttl >> len;

            quint16 pos_before = resp.pos();
            if (atype == PTR)
            {
                QString tmpname = get_addr(resp).join(".");
                ptrs[aaddr] = tmpname;
            }
            else if(atype == TXT)
            {
                Bytestream tmp;
                while(resp.pos() < pos_before+len)
                {
                    resp/resp.getU8() >> tmp;
                    if(tmp >>= "rp=")
                    {
                        std::string tmprp;
                        tmp/tmp.remaining() >> tmprp;
                        rps[aaddr] = tmprp.c_str();
                    }
                }
            }
            else if (atype == SRV)
            {
                quint16 prio, w, port;
                resp >> prio >> w >> port;
                QString target = get_addr(resp).join(".");
                ports[aaddr] = port;
                targets[aaddr] = target;
            }
            else if(atype == A)
            {
                quint32 addr;
                resp >> addr;
                QHostAddress haddr(addr);
                AAs.insert(aaddr, haddr.toString());
            }
            else
            {
                resp += len;
            }
            Q_ASSERT(resp.pos() == pos_before+len);

        }

        for(QMap<QString,QString>::Iterator it = ptrs.begin(); it != ptrs.end(); it++)
        {
            quint16 port = ports[it.value()];
            QString target =  targets[it.value()];
            QString rp = rps[it.value()];

            for(QMultiMap<QString,QString>::Iterator ait = AAs.begin(); ait != AAs.end(); ait++)
            {
                if(ait.key() == target)
                {
                    QString ip = ait.value();
                    QString addr = ip+":"+QString::number(port)+"/"+rp;
                    if(!_found.contains(addr))
                    {
                        _found.append(addr);
                        _found.sort(Qt::CaseInsensitive);
                    }
                }
            }
        }
    }
    this->update();

}