Skype Protocol Plugin

"Marco Trevisan (Treviño)" mail at
Mon May 4 18:27:00 EDT 2009

Mark Doliner wrote:
> Eion Robb has written a Skype API protocol plugin for libpurple (the
> library that powers Pidgin and Finch) [1].  It's been brought up on
> this mailing list a few times in the past, but I don't feel like we
> came to a strong consensus on whether we believe this protocol plugin
> is in violation of our GPL license, and I think it's important that we
> do so.  Here's my best summary of the potential problems:
> 1. Does the plugin link with Skype?  If so it would be in violation of
> libpurple's license because Skype is not licensed with a
> GPL-compatible license.  There are two parts to this issue:
> a) Does the plugin link to Skype in the traditional sense?  The
> Makefile does not build against or include any Skype libraries and
> from what I can tell no Skype code is loaded into the process at build
> time or at run time.  The plugin uses different mechanisms to
> communicate with Skype depending on the platform: wm_copydata messages
> on Windows, D-Bus or X11 on Linux, and some sort of asynchronous
> delegate functions on OS-X?  It's not clear to me if the use of any of
> these constitute "linking."
> [SNIP]
> 2. Skype places a bunch of restrictions on the use of the Skype API
> (like accepting Skype's EULA) [3].  It is obviously not acceptable to
> place these restrictions on libpurple because they are not compatible
> with the GPL.  But the plugin doesn't use any source code from Skype.
> Does the use of the Skype API actually impose those restrictions on
> the software?  It seems like those restrictions would be placed on the
> user of the software.  But this is not clear to me.
> [SNIP]
> Here's what I think we're going to decide, if you agree feel free to
> just +1 and we can keep this discussion short:
> * Strictly speaking the plugin is legally OK (although only a court
> could have the final say).
> * The plugin violates the "spirit" of our license, because it's
> basically a way for people to utilize proprietary code from our
> software.

Sorry, but I don't agree with this.
Also if I don't like Skype, I don't think at all that this kind of
plugin is in any form "linking" with a proprietary code.
Yes, it allows to use proprietary code from your software but exactly
like the most part of other protocol plugins are actually doing.

I mean, for example, the skype plugin under linux is "talking" with the
Skype client by using public D-Bus APIs, then that client will be a
gateway for the skype network.
But... The {yahoo,msn,aim,...} plugin is doing the same thing: it
"talks" with a server (using public[?] protocol specifications over
another network protocol) that is mostly running proprietary software.

So the only difference imho, is where the proprietary code is running.
The fact that is in the same host of the purple plugin, doesn't imply
that they're acting differently IMHO.

If you look at this plugin in this way, you should block any other
plugin that allows to use closed bits around.

Treviño's World - Life and Linux

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