On Mon, Nov 23, 2015 at 04:04:50PM -0800, Stephen Hemminger wrote: > On Thu, 22 Oct 2015 10:34:28 +0200 > Thomas Haller <thal...@redhat.com> wrote: > > > Kernel allows for zero IPv4 peer addresses (IFA_ADDRESS): > > > > ip address add 192.168.5.1 peer 0.0.0.0/24 dev dummy > > > > which is distinct from a usual address like: > > > > ip address add 192.168.5.1/24 dev dummy > > ip address add 192.168.5.1 peer 192.168.5.1/24 dev dummy > > > > For IPv4, a missing IFA_ADDRESS attribute means that the peer > > is 0.0.0.0. See inet_fill_ifaddr(), which does: > > > > if ((ifa->ifa_address && > > nla_put_in_addr(skb, IFA_ADDRESS, ifa->ifa_address)) || > > > > Signed-off-by: Thomas Haller <thal...@redhat.com> > > I would prefer that this apply to both IPv4 and IPv6.
The case that patch handles does not happen in IPv6. > If the kernel sends back an address, then display it. It's rather "if the kernel *does not* send back an address ...". When reviewing this patch, I tried to find an easier (and less ugly) solution, but failed. Here's the result from testing all variants: 1) ip a a 192.168.1.1/24 dev test0 2) ip a a 192.168.2.1 peer 192.168.2.1/24 dev test0 3) ip a a 192.168.3.1 peer 0.0.0.0/24 dev test0 4) ip a a 192.168.4.1 peer 192.168.4.2 dev test0 5) ip a a feed:babe::1:1/112 dev test0 6) ip a a feed:babe::2:1 peer feed:babe::2:1/112 dev test0 7) ip a a feed:babe::3:1 peer ::/112 dev test0 8) ip a a feed:babe::4:1 peer feed:babe::4:2 dev test0 cmd ifa_local ifa_address --------------------------------- 1) 192.168.1.1 192.168.1.1 2) 192.168.2.1 192.168.2.1 3) 192.168.3.1 unset 4) 192.168.4.1 192.168.4.2 5) unset feed:babe::1:1 6) unset feed:babe::2:1 7) unset feed:babe::3:1 8) feed:babe::4:1 feed:babe::4:2 No idea how this looks for decnet and ipx. Looking only at IPv6 though, the patch's check for !AF_INET before setting rta_tb[IFA_ADDRESS] = rta_tb[IFA_LOCAL] could indeed be skipped. On a side note, I'm pretty sure the later memcmp() could be skipped in many cases, at least by comparing the pointer values of rta_tb[IFA_ADDRESS] and rta_tb[IFA_LOCAL]. Cheers, Phil -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
