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... Best regards Michael > > That isn't implementation friendly at all. > > 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 > -- 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
