[nylug-talk] can you redirect a socket

[Peter C. Norton]

On Thu, Aug 10, 2006 at 08:08:38PM -0400, Tim Gales wrote:
> But when I look at the man page for openlog (as called by a C program),
> I don't see an option which allows pointing to a non-standard socket. 
> And this seems like there is no way to pick which logger you want to
> speak to from a C program. (I realize this is probably a little unusual 
> because syslog-ng seems to have been engineered as a replacement for 
> syslogd -- and was not intended to be run side-by-side)

No, generally not. Syslog is not one of the greatest softwares ever
written.
 
> One idea that springs to mind it trying to chroot the C apps
> so that they will be jailed to syslog-ng and when they write to
> /dev/log it will be syslog-ng's socket.

Yeah, that'd work. That's a lot of chrooted apps, though. IMO you'd be
better off, in a custom app, writing your own libsyslog that wraps
openlog, closelog, etc. but also reads the desired syslog socket as a
string from the environment and uses that for the open() call, and
LD_PRELOAD that library for the apps that need it. It is a bit less
configuration-heavy than having to chroot() everything. It should be
straightfoward to write the openlog/closelog/syslog wrapper.
 
> But I was wondering if there is a way to redirect an already
> created socket and point it to another one.

A symlink?
 
> What I would like to do is be able to, on a per process basis,
> send messages to either the system logger or syslog-ng

OK, the LD_PRELOAD solution should work.
 
> I have the nagging feeling that I am misunderstanding something
> fundamental about Linux based OS'S.

Nah, you're running into the programming from a simpler age. Syslog is
old, syslog is bad, but syslog is the way it's done. It will hopefully
go away in the future now that there's less bogus talk about standards
bodies being relevant, and more actual pedal to the metal "does this
work as well as on linux/bsd/solaris" questions going on.

> Any help would be appreciated.

Let me know if you need more information.

-Peter

-- 
The 5 year plan:
In five years we'll make up another plan.
Or just re-use this one.