From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH net-next 0/6] A step closer to RFC 6458 compliancy Date: Wed, 18 Jun 2014 09:25:13 -0400 Message-ID: <53A19339.80908@gmail.com> References: <1403017296-28469-1-git-send-email-geirola@gmail.com> <063D6719AE5E284EB5DD2968C1650D6D1725DEC9@AcuExch.aculab.com> <53A08C10.70103@gmail.com> <063D6719AE5E284EB5DD2968C1650D6D1725E555@AcuExch.aculab.com> <84A786A6-D242-4DC6-8FC4-573A91A88311@lurchi.franken.de> <063D6719AE5E284EB5DD2968C1650D6D1725E8B7@AcuExch.aculab.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Geir Ola Vaagland , "netdev@vger.kernel.org" , "linux-sctp@vger.kernel.org" To: David Laight , 'Michael Tuexen' Return-path: Received: from mail-qg0-f45.google.com ([209.85.192.45]:47734 "EHLO mail-qg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752271AbaFRNrh (ORCPT ); Wed, 18 Jun 2014 09:47:37 -0400 In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D1725E8B7@AcuExch.aculab.com> Sender: netdev-owner@vger.kernel.org List-ID: On 06/18/2014 09:16 AM, David Laight wrote: > From: Michael Tuexen [ >> On 18 Jun 2014, at 10:42, David Laight wrote: >> >>> From: Vlad Yasevich >>>> On 06/17/2014 11:36 AM, David Laight wrote: >>>>> From: Of Geir Ola Vaagland >>>>>> These patches are part of my master thesis project. I have been searching for discrepancies >> between >>>>>> the socket API specificiation in RFC 6458 and the current Linux SCTP implementation. The >> following >>>>>> patches are my humble attempts at getting somewhat closer to compliancy. >>>>> >>>>> I've just been reading RFC 6458 - HTF did it get past the editors and >>>>> then published in its current form? >>>>> Lots of the structures have implied padding. >>> ... >>>> I've argued the padding issue, but the editor stance is that it's implementation >>>> dependent. >>> >>> It wouldn't be as bad if the RFC said that the structure contained the >>> fields that followed (as is typical of the posix definitions), >>> but instead it gives a definition of the structure. > >> That would have been a possibility, but it was never suggested. >> As far as I know, C does not guarantee the memory layout for structs, >> except for the sequence of the components. So a compiler might add >> some padding at any place. When implementing this, you need to take >> care of this (and your job might be simpler, since you might only >> work with a specific set of compilers). >> In FreeBSD we also added some padding to some structures since they >> "evolved" during the lifetime of of the internet draft and we wanted >> to preserve some compatibility. >> I agree, that one must take care of the implied padding and I will double >> check how this is handled in FreeBSD. Not sure... > > You need to add explicit named pad fields in order to zero them. > (since you don't really want a memset()) > That is against my reading of the RFC. > > What does FreeBSD do about the 'sockaddr_storage'? > I'd have thought it had the same rules as NetBSD - where (IIRC) it should never > be instantiated, but only exists as a pointer type for function parameters. > I don't remember any such rules when sockaddr_storage was defined. Can you point to any document stating such rules? It is definitely useful as a container object at times. -vlad