Re: Question about netinet6/in6.h
- Reply: Mike Karels : "Re: Question about netinet6/in6.h"
- In reply to: Mike Karels : "Re: Question about netinet6/in6.h"
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Date: Fri, 26 Apr 2024 23:06:31 UTC
On Fri, Apr 26, 2024 at 4:21 PM Mike Karels <mike@karels.net> wrote: > On 26 Apr 2024, at 15:49, Mike Karels wrote: > > > On 26 Apr 2024, at 15:01, Warner Losh wrote: > > > >> This has to be a FAQ > >> > >> I'm porting a program from Linux, I often see an error like: > >> ./test/mock-ifaddrs.c:95:19: error: no member named 's6_addr32' in > 'struct > >> in6_addr' > >> 95 | ipv6->sin6_addr.s6_addr32[3] = 0; > >> | ~~~~~~~~~~~~~~~ ^ > >> but yet, we kinda define them, but only for the kernel and boot loader: > >> /* > >> * IPv6 address > >> */ > >> struct in6_addr { > >> union { > >> uint8_t __u6_addr8[16]; > >> uint16_t __u6_addr16[8]; > >> uint32_t __u6_addr32[4]; > >> } __u6_addr; /* 128-bit IP6 address */ > >> }; > >> > >> #define s6_addr __u6_addr.__u6_addr8 > >> #if defined(_KERNEL) || defined(_STANDALONE) /* XXX nonstandard */ > >> #define s6_addr8 __u6_addr.__u6_addr8 > >> #define s6_addr16 __u6_addr.__u6_addr16 > >> #define s6_addr32 __u6_addr.__u6_addr32 > >> #endif > >> > >> I'm wondering if anybody why it's like that? git blame suggests we > imported > >> that from kame, with > >> only tweaks by people that are now deceased*.* > >> > >> Why not just expose them? > > > > Looks like only s6_addr is specified in the RFCs (2553 and 3493). Oddly, > > though, the RFCs give an example implementation using that union with > > different element names (like _S6_u8), and show the one #define. > > Similarly, POSIX specifies only s6_addr, but it allows other members > > of the structure, so I don't see a problem with exposing them all even > > in a POSIX environment. > > > > I would have no objection to exposing all four definitions, especially > > if Linux apps use them. > > I put the change, along with an explanatory comment, in > https://reviews.freebsd.org/D44979. Comments welcome. > Thanks! I was testing a similar change, but I like yours better... though maybe we should just make it visible when __BSD_VISIBLE is true.... I'll have to look closely at what Linux does here... I think they have it always visible, or at least musl does that (glibc is harder to track down due to the many layers of indirection). Warner