After Powershell New-NetIPAddress, icmpSendEcho2 returns 0, GetLastError returns 0

Question

Using QT5.7.0, after executing a Powershell command New-NetIPAddress, waitForFinished () and then using icmpSendEcho2 returning 0, I get a return value of 0 when calling GetLastError 0, what can cause this behaviour?

I am using a 64bit Windows 10 OS where I execute the .exe and the address i am trying to ping is reachable. And when i change the IP address of an interface I get at "random" the mentioned error and from time to time I get an answer from the next router - destination unreachable or ping successful when i hit the right interface.

From the documentation MSDN IcmpSendEcho2 i read that after returning 0, I should check GetLastError. And from the documentation Error Codes 0 - 499 a return value of 0 means no Error.

In a few threads there was mentioned that another windows process can execute in the meantime. Could this be the case that the GetLastError returns 0?

This Problem occurs when i change the IP and ping afterwards. When the IP is already set, I ping without changing the IP Address and there the behaviour is like i think it should be.

The code executes in this order, simplified:

if (ipIsSet()==false){ //check if the IP address is already configured
   changeIP(interface,IPAddress,maskPrefix);
   ping();
} else {
   ping();
}

where the changeIP Function contains the following:

int  ipconfig::changeIP(QString interfaceNew, QString newIPAddress, QString newSubnet){

   QProcess IPProcess;
   QStringList commands;
   commands.clear();
   commands <<"New-NetIPAddress"<<"-InterfaceAlias"<<"\""+interfaceNew+"\""<<"-IPAddress"<<"\""+newIPAddress+"\""<<"-PrefixLength"<<newSubnet;
   IPProcess.start("powershell",commands);
   IPProcess.waitForFinished();
   QString pStdout = IPProcess.readAllStandardOutput();
   QString pStderr = IPProcess.readAllStandardError();
   if (pStderr.size() > 1){    //Error
       emit status("Fehler bei Adapter "+interfaceNew+".\ Folgender Fehler ist aufgetreten: \n"+pStderr+"\n");
       return 0;
   } else {
       emit status("Adapter "+interfaceNew+" wurde mit IP konfiguriert.\n");
       return 1;
   }
   return 0;
} //end change IP

and the ping() function contains this:

int ipconfig::ping(){


dwRetVal = 0, dwError = 0, replySize = 0;
emit status("Ping wird initialisiert.\n");
hIcmpFile = IcmpCreateFile();
if(hIcmpFile==INVALID_HANDLE_VALUE){
    emit status("Windows Handle konnte nicht erstellt werden.\n");
    emit pingFinished();
    return 0;
}

replySize = sizeof(ICMP_ECHO_REPLY)+sizeof(SendData)+8;
ReplyBuffer = (VOID*)malloc(replySize);
if(ReplyBuffer==NULL){
    emit status ("Buffer Speicher konnte nicht belegt werden.\n");
    emit pingFinished();
    return 9;
}
QByteArray array = pingAddress.toLocal8Bit();
const char* buffer = array.data();
ulIPAddr = inet_addr(buffer);
qDebug()<<ulIPAddr;


dwRetVal = IcmpSendEcho2(hIcmpFile, NULL,NULL, NULL, ulIPAddr, SendData, sizeof(SendData),
        NULL, ReplyBuffer, replySize, 1000);
emit status ("dwRetVal = "+QString::number(dwRetVal));
if (dwRetVal != 0){
    PICMP_ECHO_REPLY pEchoReply = (PICMP_ECHO_REPLY)ReplyBuffer;
    struct in_addr ReplyAddr;
    ReplyAddr.S_un.S_addr = pEchoReply->Address;
    emit status ("Sende Ping zu "+pingAddress);
    if (dwRetVal>1){
        qDebug()<<"Antwort: "<<dwRetVal;
    } else {
        qDebug()<<"Antwort: "<<dwRetVal;
    }
    QString str = inet_ntoa(ReplyAddr);
    emit status ("Antwort von: " +  str);
      if (ReplyAddr.S_un.S_addr == ulIPAddr){
        emit status("Ping erfolgreich.\n");
        emit pingFinished();
        return 1;
    }
    emit status ("Antwort von falscher Adresse.\n");
    emit pingFinished();
    return 404;
}
else {
    qDebug()<<"ICMP fehlgeschlagen";
    dwError=GetLastError();
    settingsLogging(dwError);
    switch (dwError) {
    case IP_BUF_TOO_SMALL:
        qDebug()<<"ReplyBuffer zu klein";
        emit status ("Antwort Buffer zu klein.\n");
        emit pingFinished();
        return 8;
        break;
    case IP_REQ_TIMED_OUT:
        qDebug()<<"Timeout";
        emit status ("Timout bei Ping.\n");
        emit pingFinished();
        return 7;
        break;
    default:
        emit status ("Unbekannter Fehler bei Ping: "+QString::number(dwError));
        emit pingFinished();
        return 10;
        break;
    }
    emit status ("Extended Error.\n");
    //emit IPSetStatus(false);
    emit pingFinished();
    return 100;
}
}

After Powershell New-NetIPAddress, icmpSendEcho2 returns 0, GetLastError returns 0

0 Answers0