the problem frequently occurs on the client side: admin need to configure stunnel for multiple users.

every user has own key, certificate, own permissions on file system (for log-files, etc)

this patch allow to write flexible config.

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

cert = ${HOME}/.config/my.pem (other)

output = %APPDATA%\stunnel.log (windows)
output = ${HOME}/stunnel.log (other)

CAfile = %ALLUSERSPROFILE%\ourCAbundle.crt (windows)
CAfile = /etc/ssl/certs/ourCAbundle.crt (other, not using variables)

"secure" :) random port example:
...

[srv1]

accept = 127.0.0.1:%SRV1_PORT% (windows)
accept = 127.0.0.1:${SRV1_PORT} (other)
...

start stunnel (batch-file or shell-script):

set SRV1_PORT=%RANDOM% (windows)

limitations:

1. don't support unicode on windows (localized usernames, files, etc)

2. only ${NAME} syntax supported on *nix (not $NAME).