On 06/18/2014 09:16 AM, David Laight wrote: > 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. > 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 -- 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
