Application Crashing after Receiving few UDP packets

[Griffolyon-aka-Rick]

Hi,

I am developing an application which will capture UDP packets send from a server and display it on my screen.

Socket is correctly created and i do receive some 3 to 4 packets every time and successfully display it on my screen also. Then my app crashes..

I use RecV() in blocking mode and on successful receiving of message calls back the same function after 1 ms after updating on screen.
I tried to use the same logic in non-blocking mode too with timer update every 1 ms, but it crashes as soon as it gets first message.

I tried using RecvFrom() also after i read one post in this forum, but without sucess.

Can anyone suggest a method to overcome this issue.

[symbianyucca]

first thing to do would be to check the panic code: http://www.developer.nokia.com/Commu...ded_panic_code , second thing to do would be to find out which code line is giving the panic.

[Griffolyon-aka-Rick]

I got the panic code E32USER-CBASE 46

[symbianyucca]

then you could check the out from SDK docs, its basically documented as "This panic is raised by an active scheduler, a CActiveScheduler. It is caused by a stray signal. "

so as you have it only time to time, just make sure:
1. You have only one active request active at any time
- use Cancel() before attempting to start any new request
- if cancelling is not an option, then check whether there is active request already, before attempting to make one.
2. Do remember to call SetArtive() right after each time you start active request , and make sure there is no if etc. clauses which could lead to situation where the SetActive() is not called, or is called without setting active request
3. Always call Cancel() in the active objects destructor

[Griffolyon-aka-Rick]

My RunL function of timer is giving me the crashing issue..
But before i call the timer function again using After(), I am making sure that i cancel the timer..

the function i wrote for monitoring the data is:
Receive Flow : Blocking mode
socket.RecvFrom(data,serverAddr,10,status);
User::WaitForRequest(status);
Display_on_UI(data);
iTeState = EReceive;
iTimer->Cancel();
iTimer->After(100);

I will read on SetActive() and try to modify the code accordingly, if that is the case

[wizard_hu_]

This particular piece of code is correct in its current form. However synchronous network communication is likely going to kill your UI code on the longer run.
Is iTimer something derived from CTimer?

[Griffolyon-aka-Rick]

@pavarang
I'm developing a GUI App

@wizard_hu
I'll try the way u suggested..
Does that mean i can eliminate use of variable aStatus and directly use iStatus?

[symbianyucca]

Does that mean i can eliminate use of variable aStatus and directly use iStatus?

Yes, and you don't need to define iStatus either, its defined for the CActive class already, so you get it when you derive your active object from CActive base class.

[Griffolyon-aka-Rick]

I am using this code for network communication using UDP..
My code is getting crashed in this part of code in Timer function -

void CExampleTimer::RunL()
{
iNotify.TimerExpired(this,iStatus.Int());
}

iTimer is derived from RTimer.

If i derive iTimer from CTimer will it resolve the crash??

[symbianyucca]

its likely not getting E32USER-CBASE 46 on that line, its likely getting it before it reaches that line. if it really does it after that line, then show what's done in TimerExpired

[Griffolyon-aka-Rick]

I have added CActive to my base class in header file with e32base.h in include also
class CSocket_UDPContainerView : public CAknView, public MExampleTimerNotify, public CActive

I changed my code to the below and no error is showing in this part of code
void CSocket_UDPContainerView::Sen_UDP()
{
TBuf8<100> aData;

TInetAddr servAddr;

servAddr.SetAddress(INET_ADDR(111,11,11,111));
servAddr.SetPort(200);

aData.Copy(_L("Test Data"));

socket.SendTo(aData, servAddr, 10, iStatus);
SetActive();
}

Now I'm getting an error "no matching function for call to CActive::Active()" at beginning of this function
CSocket_UDPContainerView::CSocket_UDPContainerView()
{
iSocket_UDPContainer = NULL;
udpTimer = NULL;
}

& virtual functions are abstract, cannot allocate an object of type CSocket_UDPContainerView, CBase is an ambigous base of 'CSocket_UDPContainerView' at the first 2 lines of definition
CSocket_UDPContainerView* CSocket_UDPContainerView::NewLC()
{
CSocket_UDPContainerView* self = new ( ELeave ) CSocket_UDPContainerView();
CleanupStack::PushL( self );
self->ConstructL();
return self;
}

I think it is due to some wrong initialization of active scheduler. I tried different ways mentioned in the docs you have suggested but with no results
Can you help me to get things right..

[symbianyucca]

You should not derive the CActive in the same class that you do CAknView, instead do move thye active objects stuff into a new class, and derive it from CActive

[Griffolyon-aka-Rick]

You should not derive the CActive in the same class that you do CAknView, instead do move thye active objects stuff into a new class, and derive it from CActive

So i need to create a new class and derive active object from it right??
All the supporting variables i have declared it in CSocket_UDPContainerView, will accessing those values in new class will create issues??

Also i tried porting the app in E6 phones i have.. it is sending and receiving packets, but Iam not able to access the IP address from Socket

TInetAddr addr;
TBuf<64> aIP;
addr = TInetAddr::Cast(iNameRecord.iAddr);
addr.SetPort(200);
addr.Output(aIP);

I tried accessing aIP it is returning '::1' - Same code is showing valid address during debug

[Griffolyon-aka-Rick]

I put a break-point at the end braces and checked.. and Yes it is crashing before it reaches there..
When I am doing single stepping the code seems to work fine - with no crashes.

This is what i wrote in timer expiry function
void CSocket_UDPContainerView::TimerExpired(TAny* aTimer,TInt aError)
{
switch (iTeState)
{
case EReceive:
{
Receive_UDP_Socket();
}
break;

}
}

void CSocket_UDPContainerView::Receive_UDP_Socket()
{
socket.RecvFrom(data,serverAddr,10,status);
User::WaitForRequest(status);
Display_on_UI(data);
iTeState = EReceive;
iTimer->Cancel();
iTimer->After(100);
}

So which line is giving me trouble here??

[symbianyucca]

likely you have some problems in your timers, After function then. likely the last line called is the iTimer->After(100);, so do check what you do inside it.

Though have you checked that it leave the function ?
I can not actually understand why you are using non-automatic variable for the status, when you are using User::WaitForReques(), basically if you use User::WaitForReques() you should use local variable there, and only use class member variable with real Active object usage.