Experimental Physics and
Industrial Control System

Michael Davidsaver via Core-talk <core-talk at aps.anl.gov> · Mon, 28 Jun 2021 22:20:54 -0700

On 6/27/21 2:38 PM, Freddie Akeroyd - STFC UKRI via Core-talk wrote:
> Hi,
> 
>  
> 
> I’m getting osiSockTest failures with epics 7 when I run it locally on my windows desktop. The issue seems to be that in udpSockFanoutTestRx() a UDP packet is picked up from the main network (looks to be from our gateway on the same subnet) and this packet is too big for the buffer passed to recvfrom()  resulting in recvfrom() returning WSAEMSGSIZE and the test terminating early.  This can be fixed by either changing the error check to be:

Interesting, I was under the impression that recvfrom() would silently truncate.
The Linux manpage doesn't mention EMSGSIZE.  I guess this is either Linux specific,
or an omission.

https://linux.die.net/man/2/recvfrom

Anyway, thank you for running the tests and reporting!

>     if(n<0 && SOCKERRNO != SOCK_EMSGSIZE) {
> 
>  
> 
> (with SOCK_EMSGSIZE= WSAEMSGSIZE on WIN32, EMSGSIZE elsewhere) or by increasing the size of the body part of the CASearch  structure – it looks like the entire structure would currently need to be at least 1024 bytes for packets on our network.

I'm testing a change to ignore large messages and retry.

> --- a/modules/libcom/test/osiSockTest.c
> +++ b/modules/libcom/test/osiSockTest.c
> @@ -243,6 +243,10 @@ void udpSockFanoutTestRx(void* raw)
>          buf.bytes[sizeof(buf.bytes)-1] = '\0';
>  
>          if(n<0) {
> +#ifdef _WIN32
> +            if(errno==WSAEMSGSIZE)
> +                continue;
> +#endif
>              testDiag("recvfrom error (%d)", (int)SOCKERRNO);
>              break;
>          } else if((n==sizeof(buf.bytes)) && buf.msg.cmd==htons(6) && buf.msg.size==htons(16)

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System