Sly Midnight <[email protected]> writes:
>>Synopsis: rtadvd does not detect dynamic changes to monitored
> interface
>>Category: system
>>Environment:
> System : OpenBSD 5.8
> Details : OpenBSD 5.8 (GENERIC.MP) #1: Mon Nov 2 11:58:21
> EST 2015
>
> [email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
>
> Architecture: OpenBSD.amd64
> Machine : amd64
>>Description:
> rtadvd is designed to detect and automatically determine which
> prefixes are local to a specific link when it is fired up without
> a configuration file and just started with an interface
> identifier as a command line argument.
>
> It is able to detect automatically when an IPv6 address is added
> to the monitored interface and discern the prefix on it's own
> and start sending out Advertisements with the prefix on that
> same interface announcing itself as the default gateway for that
> prefix.
>
> Starting with about OpenBSD 5.5 or 5.6 I noticed the daemon
> would pickup the available prefixes on the monitored interface
> upon startup, but not detect when an address was either removed
> or added. Addresses removed, continued to have the
> prefix advertised, and addresses added would not be advertised
> until the daemon was restarted.
>
> The delay in reporting this was because the daemon does pickup
> the information initially upon startup and thus does mostly work.
> And since IPv6 addressing changes on my network are not frequent
> I didn't have a way to easily confirm if my initial suspicions
> were reproducible without affecting my network with testing.
> But now some other change in the boot process or the other
> software I use to provision my IPv6 connectivity (or my ISP now
> responds slower), it won't even detect the first address added
> to the monitored interface after boot up, because the rtadvd
> daemon has already started way before my other dhcpv6 client
> has had the opportunity to ask for and receive a delegated
> prefix. So after my firewall box reboots, I have to login and manually
> restart rtadvd after I confirm I have a valid IPv6 address on
> the internal interface I run rtadvd on before hosts on my internal
> network can gain IPv6 connectivity.
>>How-To-Repeat:
> Install a recent version of OpenBSD 5.8 and enable IPv6 on at
> least 1 interface.
> Load rtadvd with that interface identifier as the sole command
> line argument.
> Now add an IPv6 address to that interface and then proceed to
> send a SIGUSR1 signal to it's PID, and check /var/log/daemon and
> notice it does not have knowledge of the newly added IPv6
> address and it's prefix.
>
> Restart daemon and send another -SIGUSR1 and now notice it is
> aware of the prefix.
> Delete that address and send yet another -SIGUSR1 and notice it
> still thinks it should be advertising for that prefix that was removed.
>>Fix:
> I do not know what method rtadvd employs to detect changes in
> the monitored interface's addressing.
> A member of the mailing list who also has some experience with
> IPv6 suggested it monitors the routing table for changes to routes
> on that interface. But I am not sure.
>
> Only available work around is to restart daemon every time there
> is an IPv6 addressing change on that interface.
Thanks for your detailed report; the following diff should help.
(I did not try to track down the commits that did break this feature.)
Index: if.c
===================================================================
RCS file: /cvs/src/usr.sbin/rtadvd/if.c,v
retrieving revision 1.30
diff -u -p -r1.30 if.c
--- if.c 3 Nov 2015 15:59:31 -0000 1.30
+++ if.c 26 Nov 2015 23:22:04 -0000
@@ -256,7 +256,7 @@ get_next_msg(char *buf, char *lim, int i
continue;
if ((gw = rti_info[RTAX_GATEWAY]) == NULL ||
- gw->sa_family != AF_LINK)
+ gw->sa_family != AF_INET6)
continue;
if (ifindex && SDL(gw)->sdl_index != ifindex)
continue;
@@ -319,12 +319,8 @@ int
get_rtm_ifindex(char *buf)
{
struct rt_msghdr *rtm = (struct rt_msghdr *)buf;
- struct sockaddr *sa, *rti_info[RTAX_MAX];
-
- sa = (struct sockaddr *)(buf + rtm->rtm_hdrlen);
- get_rtaddrs(rtm->rtm_addrs, sa, rti_info);
- return(((struct sockaddr_dl *)rti_info[RTAX_GATEWAY])->sdl_index);
+ return rtm->rtm_index;
}
int
--
jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE
