Re: Is there a reason why GNUnet forcefully sends a message of type 6?

[Christian Grothoff]

On 5/23/20 12:48 AM, Alessio Vanni wrote:
> Thank you.  It's better than nothing I suppose; at least I'm not left
> here scratching my head, as I can look into those places you suggested.
> Anyway, if possible I'd still like to know why `GNUNET_SERVICE_start'
> adds a handler for that type of message. It's convenient for the core
> which might actually use those messages, but unless there is another
> reason you might want to add it from a function not used to deal with
> third-party applications too.  I mean, it's still adding a handler for
> message type 6 which might be an application-specific message type...

Actually, no. Type 6 implements our *Affero* GPL mechanism to provide
anyone who accesses *any* GNUnet service with the means to download the
source code. GNUnet is released under the AGPL, which specifically
states that such a mechanism to obtain the source must not be disabled.

So a third-party application would be in violation of the AGPL license
if it disabled this particular handler. Basically, that's the one
"freedom" the *Affero* GPL takes away: the freedom to remove or disable
a "download source" mechanism.

Now, admittedly it could be documented better, but it was mostly added
as a quick hack before a release when we switched to the AGPL.

Finally, in general we'll want even third-party applications to use
message types that are "registered" globally. We recently setup
https://gana.gnunet.org/ which will be used to facilitate this.

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