From 5bfe25432f47fc51db50d501a15474b6dadf73af Mon Sep 17 00:00:00 2001 From: glebius Date: Sat, 15 Oct 2011 18:41:25 +0000 Subject: Add support for IPv4 /31 prefixes, as described in RFC3021. To run a /31 network, participating hosts MUST drop support for directed broadcasts, and treat the first and last addresses on subnet as unicast. The broadcast address for the prefix should be the link local broadcast address, INADDR_BROADCAST. --- sys/netinet/in.c | 13 +++++++++---- sys/netinet/in.h | 2 ++ 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/sys/netinet/in.c b/sys/netinet/in.c index d0be11f..bba364d 100644 --- a/sys/netinet/in.c +++ b/sys/netinet/in.c @@ -897,8 +897,11 @@ in_ifinit(struct ifnet *ifp, struct in_ifaddr *ia, struct sockaddr_in *sin, */ ia->ia_ifa.ifa_metric = ifp->if_metric; if (ifp->if_flags & IFF_BROADCAST) { - ia->ia_broadaddr.sin_addr.s_addr = - htonl(ia->ia_subnet | ~ia->ia_subnetmask); + if (ia->ia_subnetmask == IN_RFC3021_MASK) + ia->ia_broadaddr.sin_addr.s_addr = INADDR_BROADCAST; + else + ia->ia_broadaddr.sin_addr.s_addr = + htonl(ia->ia_subnet | ~ia->ia_subnetmask); } else if (ifp->if_flags & IFF_LOOPBACK) { ia->ia_dstaddr = ia->ia_addr; flags |= RTF_HOST; @@ -1230,9 +1233,11 @@ in_broadcast(struct in_addr in, struct ifnet *ifp) if (ifa->ifa_addr->sa_family == AF_INET && (in.s_addr == ia->ia_broadaddr.sin_addr.s_addr || /* - * Check for old-style (host 0) broadcast. + * Check for old-style (host 0) broadcast, but + * taking into account that RFC 3021 obsoletes it. */ - t == ia->ia_subnet) && + (ia->ia_subnetmask != IN_RFC3021_MASK && + t == ia->ia_subnet)) && /* * Check for an all one subnetmask. These * only exist when an interface gets a secondary diff --git a/sys/netinet/in.h b/sys/netinet/in.h index d5e4290..52844f0 100644 --- a/sys/netinet/in.h +++ b/sys/netinet/in.h @@ -392,6 +392,8 @@ __END_DECLS #define IN_LOOPBACKNET 127 /* official! */ +#define IN_RFC3021_MASK (u_int32_t)0xfffffffe + /* * Options for use with [gs]etsockopt at the IP level. * First word of comment is data type; bool is stored in int. -- cgit v1.1