[Xymon] how to learn what is crashing my rrd handler?

[John Thurston]

On 8/27/2014 4:08 PM, Jeremy Laidman wrote:
> On 28 August 2014 05:10, John Thurston <john.thurston at alaska.gov
> <mailto:john.thurston at alaska.gov>> wrote:
>
>     And I think the thing which ran off the end of the string was the
>     debug process :p I'm still looking at source (and my C is very, very
>     bad), but I suspect the debug print process is choking on the
>     absence of an attribute in the procols.cfg
>
> The "Sendtext" line has only the date string, so that's probably the
> data that caused the crash.  I'm guessing you haven't re-defined the
> protocols.cfg entry for [telnet], so I'm struggling to imagine where the
> bad data could have come from.  But perhaps worth removing the "telnet"
> test for that host and see if the crashing stops.

The telnet test is defined for only one host (out of 600) in my 
hosts.cfg, and it is never the host identified in the remnants of the crash.

It looks like (with 4.3.17), in debug mode, lines 324-340 of 
netservices.c dump the currently defined service list. They correctly 
send the contents of the service list for:
  ftp
  ftps
  ssh
  ssh1
  ssh2
and they print the name for:
  telent
and then they die when they are asked to print the Sendtext for "telnet"

My protocols.cfg contains:

> [ssh|ssh1|ssh2]
>    send "SSH-2.0-OpenSSH_4.1\r\n"
>    expect "SSH"
>    options banner
>    port 22
>
> [telnet]
>    options banner,telnet
>    port 23

There is no "send" attribute defined. I don't think there has ever been 
such an attribute defined. The files in the source directories 
(~/xymon-4.3.17/xymonnet/protocols.cfg) do not contain a "send" 
attribute. The "send" attribute is defined for most, but not all of the 
other protocols in the file.

Has anyone running 4.3.17 successfully run their rrd_data handler in 
debug mode? I don't think it can do it.

This looks to me like a code defect, wherein the dump_tcp_services 
function is not checking for a null string prior to finding its length 
and passing the information to dbgprintf. I'm just a lowly sysadmin 
whose last exposure to C was more than 25 years ago. Can someone with 
some C experience confirm or deny my hypothesis?

-- 
    Do things because you should, not just because you can.

John Thurston    907-465-8591
John.Thurston at alaska.gov
Enterprise Technology Services
Department of Administration
State of Alaska