On 18 Jun 2014, at 15:25, Vlad Yasevich <vyasevich@xxxxxxxxx> wrote: > 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. I agree. The description would be OK for struct sockaddr. I have never instantiated a variable of that type. The only use (I know of) of struct sockaddr_storage is as a container object. Best regards Michael > > -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
