Re: Content Filtering

On Sat, 2004-09-25 at 10:16 -0400, Tres Seaver wrote:
> Henrik Nordstrom wrote:
>
> > Note: Squid is GPL and as a result you are only allowed to use GPL
> > modules with Squid. If your filter implementation is not GPL then
> > dynamic linking is not an option.
>
> IANAL, bu wouldn't it be truer to say that the GPL does not allow
> *distribution* of Squid linked with software under non-GPL-compatible
> licenses?
>
> See:
> http://www.gnu.org/licenses/gpl-faq.html#TOCGPLRequireSourcePostedPublic
>
> and:
> http://www.gnu.org/licenses/gpl-faq.html#InternalDistribution
>
> And I am not sure that dynamic linking triggers the "derivative work"
> provisions, particularly if Squid continues to function without the
> presence of the library.

This is incredibly tricky to get right: If you take the position that
dynamic plugins are derived works (of the thing they link into - which
here would be the squid routines), you end up with interface
copyrighting (that is, something that has no code, may only be a couple
of lines, and is trivially the same for similar requirements - bleuch).
if you take the position that dynamic plugins are not derived works,
then someone can write a proprietary gzip compression module for squid,
ship it at whatever cost, leveraging /all the squid internals/. Which is
also quite unattractive. AFAICT there is no standard that one can apply
neutrally and externally to instances of dynamic linking to decide
whether it would count as a derived work.

Currently it is a very messy situation :(

Rob

> Note particulary:
>
> http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins
>
> and the use of the word "believe" in that language. The GPL itself does
> not mention dynamic linking at all.
>
> Tres.

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