#11 Seg. fault after pulling the Plc's network cable

[Natalie Kather]

Referring: libnodave 0.8.4.4
The situation:
After establishing a TCP connection to the PLC with libnodave, I pull the network cable of the PLC to find out what happens if the network breaks down. Then I try to request some diagnostic data (SZL) from the PLC. However, there is a segmentation fault in function daveReadSZL() in line 1106, namely in the memcpy() command:

if (cpylen > 0) memcpy((uc *)buffer+len,p2.udata,cpylen);

What happens?

daveBuildAndSendPDU() returns -1250/daveResTimeout. We can prevent the segmentation fault if we check in daveReadSZL() the value of

res=daveBuildAndSendPDU(dc, &p2, pa, sizeof(pa), da, sizeof(da));

BEFORE entering the while loop.

So the solution of the problem is quite simple. We just add this comparison before the "while (p2.param[9]!=0) ..." loop, for instance in line 1098:

if (res < daveResOK)
return res;

That's it! There is no more segmentation fault that crashes the program.

Would be great if you could take over this bugfix into the official sources of libnodave.

Cheers, Natalie