[rsyslog] making a custom input module

[david at lang.hm]

my second project is to try and modify rsyslog to recieve logs from an 
application. the application sends the logs over TCP and expects an 
application-level handshake (very similar to relp). at the moment I want 
to try and avoid having to change the application (many different products 
with different release schedules), and instead teach rsyslog to deal with 
the existing log format.

at the moment I am trying to understand the imtcp module, but I am getting 
lost in the callbacks. it looks like rsyslog is calling a routine in 
imtcp, which calls a routine in tcpsrv, which calls a routine somewhere 
else to actually recieve the log.

ideally what I would like to use is to take imtcp and replace the message 
recieving/parsing logic with my own, then have it submit the parsed 
message into the queue (which looks like it would be via the SubmitMsg() 
call).

but at the moment I am lost in the twisty maze of function calls between 
source files, all of which look different.

I'm also not clear on what fields inside of the Msg structure need to be 
populated. looking at Msg.c/h I see a lot of fields there, but it looks 
like many/most of them are optional.

any pointers?

David Lang