[rancid] Re: Rancid output "Binary files differ"

[john heasley]

Wed, Nov 25, 2009 at 11:39:20AM +0000, ?rni Birgisson:
> Hi guys,
> 
> I'm wondering if anybody has seen this problem before.
> This mail is going to be a bit long, starting with a simple description of the problem,
> and then my diagnosis of it.
> 
> >From time to time I'm getting a strange output from RANCID:
> 
> -----
> 
> Index: configs/router-x
> ===================================================================
> retrieving revision 1.88
> diff -U 4 -r1.88 router-x
> Binary files /tmp/cvsQSyJ8S and router-x differ
> 
> -----
> 
> As I noticed that the revision number was quite high I looked around and it seems that this
> does happen for more than one router - but happens very often to this one.
> Most of the network equipment has had about 30-40 revisions since RANCID was installed
> but this one has 88 revisions.
> 
> If I check a few versions of the config out of CVS I can see that indeed some of the files are weird.
> 
> -bash-4.0$ cvs diff -r1.86 -r1.89
> --normal diff output showing config changes--
> -bash-4.0$ cvs diff -r1.86 -r1.87
> --normal diff output showing config changes--
> -bash-4.0$ cvs diff -r1.86 -r1.88
> cvs diff: Diffing pe
> cvs diff: Diffing pe/configs
> Index: pe/configs/router-x
> ===================================================================
> RCS file: /var/rancid/CVS/pe/configs/router-x,v
> retrieving revision 1.86
> retrieving revision 1.88
> diff -r1.86 -r1.88
> Binary files /tmp/cvsCqpVfB and /tmp/cvsp09kv5 differ
> 
> Okay, looks like version 1.88 is the weird one.
> 
> Let's fetch 1.88 and 1.89
> -bash-4.0$ cvs co -r1.88 pe/configs/router-x
> U pe/configs/router-x
> -bash-4.0$ cp pe/configs/router-x v1.88
> -bash-4.0$ cvs co -r1.89 pe/configs/router-x
> U pe/configs/router-x
> -bash-4.0$ cp pe/configs/router-x v1.89
> 
> -bash-4.0$ ls -al v1.8*
> -rw-r--r-x 1 rancid rancid 70556 2009-11-25 05:28 v1.88
> -rw-r--r-x 1 rancid rancid 70556 2009-11-25 05:28 v1.89
> -bash-4.0$ diff v1.88 v1.89
> Binary files v1.88 and v1.89 differ
> -bash-4.0$ 
> 
> --- same size of the files, but diff won't compare them because they are (or one of them is) a binary file.
> 
> -bash-4.0$ strings v1.88 | wc -l
> 1387
> -bash-4.0$ strings v1.89 | wc -l
> 1542
> 
> Now when I have a look at the files it seems that the smaller file (v1.88 and "binary") starts with a lot of \0 bytes,
> it would seem one for each character that is missing - and then continues exactly like the other one.
> Or should I say the files are exactly the same - but it's as if the first (1542 - 1387) bytes of v1.88 are 0-byte instead
> of the character that should be there.
> 
> Diff --text on them shows that v1.89 includes all the lines from v1.88 and more and there has been no real
> change to the config.
> 
> I'm running rancid version 2.3.2, with a slight change to jrancid:
> The change to jrancid is to make it backup a "show configuration | display set" version of the config as well as the
> normal "show configuration" and is done by adding one function:
> 
> sub ShowConfigurationDisplaySet {
>     print STDERR "    In ShowConfigurationDisplaySet: $_" if ($debug);
> 
>     s/^[a-z]+@//;
>     ProcessHistory("","","","# $_");
>     while (<INPUT>) {
>         tr/\015//d;
>         last if (/^$prompt/);
>         next if (/^system (shutdown message from|going down )/i);
>         next if (/^\{(master|backup)}/);
> 
>         /Unrecognized command/ && return;
>         /command is not valid/ && return;
>         /^\s+\^/ && return;
>         /syntax error/ && return;
> 
>         ProcessHistory("","","","$_");
>     }
>     return(0);
> }
> 
> 
> and one item to @commandtable:
>         {'show configuration | display set'     => 'ShowConfigurationDisplaySet'},
> 
> It could very well be that the errors are introduced because of my addition,
> but I fail to see how.

not likely.  do you have a fsys or memory problem on this host?  broken
expect/tcl?  some other unintentional change to rancid?