[vlc-devel] Re: vlc: svn commit r17999 (courmisch)

Rémi Denis-Courmont rem at videolan.org
Thu Nov 23 15:21:43 CET 2006

Le jeudi 23 novembre 2006 14:50, Marian Durkovic a écrit :
> On Thu, Nov 23, 2006 at 02:36:50PM +0100, Subversion daemon wrote:
> > r17999 | courmisch | 2006-11-23 14:36:49 +0100 (Thu, 23 Nov 2006) |
> > 4 lines Changed paths:
> >    M /branches/0.8.6/modules/misc/network/ipv4.c
> >    M /branches/0.8.6/modules/misc/network/ipv6.c
> >
> > - Only try to use SSM when the group address is SSM itself
> >   (afterall, we could specify a source/server even with ASM)
> This commit is broken. It prevents user from filtering out unwanted
> ASM sources if someone is e.g. DOSing him.

VLC has never been able to properly filter out ASM sources (and not even 
SSM sources in fact, though this is far more theoretical a problem), 
since VLC never ever used connect() toward the right source address 
when doing multicast. I DO intend to do that in 0.9.0.

If the commit is reverted, VLC will return to the very bad state where 
it fails as soon as a source address is specified for ASM (why you've 
been complaining about with SAP source-filter for so long).

> If user explicitly specified the server address, VLC should NOT
> ignore it.

Yeah, that's exactly what I am trying to fix. This has never been 
working before, except for genuine SSM traffic. And even then, it did 
not work completely since multiple subscriptions on the same system 
would still fuck everything up.

At least, it is now possible to introduce ASM source filtering without 
breaking VLC 0.8.6-17999.

> If SSM is unavailable, we have fallback to IGMPv2 with the same
> functionality, so for IPv4 this commit is duplicate.

Not at all. It avoids failing lamely if the user has for some reason a 
source address specified in addition to an ASM group address.

> If you want the same for IPv6, please implement fallback instead.

This fallback mechanism only solves backward binary compatibility for 
OSes where not all version support SSM. That's hardly related. In fact, 
I am not even sure if it really solves anything, since subscribing to 
SSM as ASM most likely will not work.

Rémi Denis-Courmont
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