Communication between plug-ins

[Daniel Kraft]

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Hi,

I've patched the Pidgin OTR plug-in to allow verification of
fingerprints via the Namecoin identity system:

  git clone -b namecoin-verify https://git.domob.eu/pidgin-otr-nmc.git

This was however only a proof-of-concept implementation, because it is
unlikely that the OTR folks will integrate Namecoin into their
official code.  However, they indicated interest in a general
"verification framework" for Pidgin-OTR that would allow other
plug-ins to provide additional verification methods just like mine,
and I want to implement that.

The basic idea is like this:  Users have the official Pidgin-OTR
plug-in installed, and additionally a separate Namecoin plug-in.  When
the fingerprint verification process is started from the OTR plugin,
it looks through all installed plug-ins, determines which of those
provide fingerprint verification and then adds those as additional
options in the UI dialog.

Is something like this possible, and if so, how would I best implement
it?  In particular, how can the communication between the OTR plug-in
and verification plug-ins be done?  I presume that
purple_plugins_get_loaded is a start which could be used by OTR on
demand to get a list of all plug-ins installed (rather, active).  But
how could verification plug-ins signal to OTR that they indeed provide
verification features?  And how can OTR then tell those plug-ins to
build their UI, and vice-versa those plug-ins tell OTR to mark
fingerprints as verified?

My first idea would be to use signals:  If I understand them
correctly, one can basically connect any signal to any GObject, thus
would it be possible to achieve what I have in mind if each
verification plug-in connected a signal handler for, say,
"pidgin-otr-start-verification" to its PurplePlugin, and OTR fired
this signal on every plug-in loaded?  Then only those which are
actually verification plug-ins would handle the signal, and could take
appropriate action.  Via the user-data field for the signal handlers,
pointers to data-structures could be exchanged that can then be used
to communicate between OTR and the verifiers.

What do you think, is this a possible approach?  Are there other
(better) ways to handle my situation?  I've not much experience with
Glib and libpurple, so any help is very much appreciated!

Thanks!  Cheers,
Daniel

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http://www.domob.eu/
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