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<== Date ==> <== Thread ==>

Subject: Re: CA gatway runs away when zero length PV name in UDP search request
From: Andrew Johnson <anj@aps.anl.gov>
To: <tech-talk@aps.anl.gov>
Date: Thu, 27 Apr 2017 12:01:17 -0500
Hi,

On 04/26/2017 07:53 PM, Shuei YAMADA wrote:
> I have a problem with CA gateway that it runs away and all PVs
> subscribing via ca-gateway become disconnected. The problem occurred 4
> times in past 6 month and each time I had to restart CA gateway. I'm
> using CA gataway 2.1.0 with EPICS base 3.14.12.3 on Scientific Linux
> 6.8 (RHEL 6.8 clone).
> 
> The log file contains following message:
> ====
> CAS Request: ? on jkjnuc31.ccr.jkcont:40325: cmd=6 cid=76 typ=5 cnt=11
> psz=32 avail=4c
> CAS:
> Apr 20 06:29:30 !!! Errlog message received (message is above)
> zero length PV name in UDP search request?

The CA network protocol probably isn't designed to handle zero-length PV
names. The CA client library rejects any attempt to connect to an empty
PV name (ca_create_channel() returns ECA_BADSTR), but as Kay has implied
the Java client library is missing some equivalent checks for a
zero-length name. However the CAS code should not crash when it sees a
bad request like that so there does seem to be a bug in our code as
well, which I have filed in a bug report at
    https://bugs.launchpad.net/epics-base/+bug/1686787

Until we can fix the problem in EPICS Base and/or CS-Studio you should
look through your CS-Studio screens and look for one that could be
trying to connect to an empty PV name "", which might be caused by a
macro substitution, such as a typo in a macro's name or not setting a
macro properly when pulling up a related display.

- Andrew

-- 
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon

Replies:
Re: CA gatway runs away when zero length PV name in UDP search request Shuei YAMADA
References:
CA gatway runs away when zero length PV name in UDP search request Shuei YAMADA

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