[stunnel-users] Public domain [PATCH] support environment variables in config file

Pierre Delaage delaage.pierre at free.fr
Wed Jun 1 10:29:13 CEST 2016

To my mind, admin tasks such as conf file customization, should be 
performed by admin scripts, not app running in admin mode.

With *GnuWin32 *sed AND echo commands, things are really simple :

*stunnel.conf :**

cert = %USERPROFILE%\.config\my.pem (windows)

output = %APPDATA%\stunnel.log (windows)

*script "envsed.bat" on Windows :**

cat stunnel.conf | ^

sed -r -e "s/^(.*)$/C\:\\Progra~2\\GnuWin32\\bin\\echo.EXE \1/e"

every envvar "à la windows" is expanded ....
Will work the same in Linux.

If we really modify stunnel to do that job, I recommend to (try to) use 
stubs for WCE trying to keep one main code, and keeping an acceptable 
behavior in WCE,
instead of playing with #if WCE #else etc ...

Another way to proceed is that stunnel recognizes a very small set of 
"pseudo-envvars", like eg we can find in samba conf files,
such as, eg, %u for current user home folder, and that it expands (or 
"translate") internally with its own logic (of course using system calls 
if needed),
but in any case, stunnel has to do some work for tokenization, something 
that I think dangerous :
it would not be good that stunnel expands ANY envvar, known or UNKNOWN, 
without being able to predict the effects on its execution.
Moreover, envars can be modified on the fly in an unpredictable way: 
what if stunnel reloads the conf after an envvar change ?
if it even does NOT detect the change, there may be issues ...and if it 
detects the change and reloads, there may be other issues...

Anyway, for the purpose of having multiple stunnel processes, running in 
user space, started from USER command line, it does not appear clear to 
me why an admin should create the USER conf files...the USER should be 
aware of what is he/she doing with stunnel?
and it is not clear why and HOW multiple users, logged-on on the ?same? 
machine, each working in USER SPACE, should run stunnel simultaneously ...

Question is also : if stunnel is running as a service, how will it deal 
with conf file containing ENVVARS, and what interest for this as 
system-wide stunnel just need one unique conf file.

Yours sincerely,

Le 31/05/2016 18:59, Dmitry Bakshaev a écrit :
> 2016-05-31 17:07 GMT+04:00 Pierre Delaage <delaage.pierre at free.fr 
> <mailto:delaage.pierre at free.fr>>:
>     Hi,
>     The difference is that, on WCE, for stunnel code, it is
>     straigthforward to access the "unique profile" stunnel.conf,
>     WITHOUT in fact dealing with envvars,
>     rather than 1/ decode %VARNAME% tokens in conf file and then ask
>     env for replacement...
>     well...ok..we can create stubs as well for getenv etc... but is is
>     much more complicated.
> "environment expanded config" feature is designed for the platform 
> that support it - on WCE is not avialable - config is static text file,
> and use static values in config files on other platform not prohibited 
> : ADMIN chooses which
> parameters USER can expand to USER own values or none.
>     For W32 platforms, communicating with a server with env vars can
>     open issues.
> example, please. every account that start stunnel has his own 
> environment, cert, key, etc.
>     BUT working in "local user sandbox", folders etc...is more secure
>     than modifying system files by everyone through envvars.
> files not modified globally, only for current USER by USER values in 
> runtime, only for specified parameters
>     More generally, I agree that a per user conf can be useful ONLY IF
>     each user is able, and "directed to" start HIS/HER STUNNEL by
>     HAND, in a user space process.
> yes. one of our scenarios.
>     But to achieve this....stunnel is ALREADY ready to go by using the
>     command line like this "stunnel myownconfig.conf", of course
>     having "my" own copy of stunnel executable.
>     So there is no real need to have an embeddef feature in stunnel
>     for conf file customization per user.
>     And, once again, as conf file are just "text files", it is quite
>     easy to create a bunch of such from a template, by text editiong
>     tools : sed on win32 is really powerful, or win32 perl engine, or
>     whatever scripting language you prefer
> this feature makes it unnecessary to copy config to every user and 
> edit files manually or using sed/perl.
> not need ADMIN intervention after adding new USER.
> adding/replace service/port not need regenerate all users config - one 
> centralized config.
> this is the primary purpose - ADMIN make one config as template for 
> all users.
> for example server scenario: we has multiple stunnel instanses on 
> gentoo linux
> and i can configure on template:
> output = /var/log/stunnel/stunnel_${SVCNAME}.log
> each instance has its own log. (SVCNAME variable contains instance 
> name from init.d startup scripts)

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