From: Michael Tuexen [ > On 18 Jun 2014, at 10:42, David Laight <David.Laight@xxxxxxxxxx> 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. David -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
