dhcpcd-discuss

Hi

On 04/03/2014 22:30, Maarten de Vries wrote:
> I have a set up at home with one host sending ICMPv6 router
> advertisements to configure my internal IPv6 network (and actually
> also doing DHCPv6, but this is irrelevant for the issue at hand I
> believe). However, I don't have a public IPv6 address, so I just want
> IPv6 on my internal network, while still configuring a custom prefix
> (in the fd00::/8 range) and properly configuring DNS information.
> Everything seems to work, but the host sending the RAs becomes the
> default gateway for every other host on the network. That default
> route is bogus, since the host in question doesn't have a public IPv6
> address. I just want IPv6 on my internal network.
>
> So, I read some more, and it would seem that setting the router
> lifetime field of the RA to 0 should do exactly what I want: prevent
> the host from becoming a default route. RFC4861 says:
>
> > The lifetime associated with the default router in units of seconds.
> >  The field can contain values up to 65535 and receivers should
> > handle any value, while the sending rules in Section 6 limit the
> > lifetime to 9000 seconds.  A Lifetime of 0 indicates that the
> > router is not a default router and SHOULD NOT appear on the default
> > router list. The Router Lifetime applies only to the router's
> > usefulness as a default router; it does not apply to information
> > contained in other message fields or options.  Options that need
> > time limits for their information include their own lifetime fields.
>
> However, when I set that field to zero, dhcpcd doesn't seem to process
> the RA at all and ignores all information, including prefix and dns
> information. If I understand the RFC correctly, this behavior is wrong
> and the prefix and dns (and other) information should still be
> processed. For the moment I "worked around it" by setting the lifetime
> to 1, meaning the route becomes invalid after one second. However, the
> route does stay in the routing table for one second, so it's quite an
> ugly workaround.

Hmmmm, I can't fault your reasoning.
This patch should fix it. I need to do some testing on it first though.
Let me know his it works for you.

Thanks

Roy

Index: ipv6.c
==================================================================
--- ipv6.c
+++ ipv6.c
@@ -980,18 +980,19 @@
 	TAILQ_FOREACH(rap, ctx->ra_routers, next) {
 		if (rap->expired != expired)
 			continue;
 		if (rap->iface->options->options & DHCPCD_IPV6RA_OWN) {
 			TAILQ_FOREACH(addr, &rap->addrs, next) {
-				if ((addr->flags & IPV6_AF_ONLINK) == 0)
+				if (addr->prefix_vltime == 0 ||
+				    (addr->flags & IPV6_AF_ONLINK) == 0)
 					continue;
 				rt = make_prefix(rap->iface, rap, addr);
 				if (rt)
 					TAILQ_INSERT_TAIL(dnr, rt, next);
 			}
 		}
-		if (rap->iface->options->options &
+		if (rap->lifetime && rap->iface->options->options &
 		    (DHCPCD_IPV6RA_OWN | DHCPCD_IPV6RA_OWN_DEFAULT))
 		{
 			rt = make_router(rap);
 			if (rt)
 				TAILQ_INSERT_TAIL(dnr, rt, next);

Index: ipv6nd.c
==================================================================
--- ipv6nd.c
+++ ipv6nd.c
@@ -606,11 +606,11 @@
 				}
 				if (rapap == ap)
 					found = 1;
 			}
 
-			if (wascompleted && found && rap->lifetime) {
+			if (wascompleted && found) {
 				syslog(LOG_DEBUG,
 				    "%s: Router Advertisement DAD completed",
 				    rap->iface->name);
 				if (ipv6nd_scriptrun(rap))
 					return;
@@ -682,15 +682,10 @@
 		    sizeof(rap->from.s6_addr)) == 0)
 			break;
 	}
 
 	nd_ra = (struct nd_router_advert *)icp;
-	/* Don't bother doing anything if we don't know about a router
-	 * expiring */
-	if ((rap == NULL || rap->lifetime == 0)
-	    && nd_ra->nd_ra_router_lifetime == 0)
-		return;
 
 	/* We don't want to spam the log with the fact we got an RA every
 	 * 30 seconds or so, so only spam the log if it's different. */
 	if (rap == NULL || (rap->data_len != len ||
 	     memcmp(rap->data, (unsigned char *)icp, rap->data_len) != 0))
@@ -998,16 +993,12 @@
 		script_runreason(ifp, "TEST");
 		goto handle_flag;
 	}
 	ipv6nd_probeaddrs(&rap->addrs);
 	ipv6_buildroutes(ifp->ctx);
-
-	/* We will get run by the expire function */
-	if (rap->lifetime) {
-		if (ipv6nd_scriptrun(rap))
-			return;
-	}
+	if (ipv6nd_scriptrun(rap))
+		return;
 
 	eloop_timeout_delete(ifp->ctx->eloop, NULL, ifp);
 	eloop_timeout_delete(ifp->ctx->eloop, NULL, rap); /* reachable timer */
 
 	/* If we're owning the RA then we need to try and ensure the
@@ -1198,27 +1189,30 @@
 	timerclear(&next);
 
 	TAILQ_FOREACH_SAFE(rap, ifp->ctx->ipv6->ra_routers, next, ran) {
 		if (rap->iface != ifp)
 			continue;
-		lt.tv_sec = rap->lifetime;
-		lt.tv_usec = 0;
-		timeradd(&rap->received, &lt, &expire);
-		if (rap->lifetime == 0 || timercmp(&now, &expire, >)) {
-			valid = 0;
-			if (!rap->expired) {
-				syslog(LOG_WARNING,
-				    "%s: %s: router expired",
-				    ifp->name, rap->sfrom);
-				rap->expired = expired = 1;
-				ipv6nd_cancelproberouter(rap);
+		if (rap->lifetime) {
+			lt.tv_sec = rap->lifetime;
+			lt.tv_usec = 0;
+			timeradd(&rap->received, &lt, &expire);
+			if (rap->lifetime == 0 || timercmp(&now, &expire, >)) {
+				valid = 0;
+				if (!rap->expired) {
+					syslog(LOG_WARNING,
+					    "%s: %s: router expired",
+					    ifp->name, rap->sfrom);
+					rap->expired = expired = 1;
+					ipv6nd_cancelproberouter(rap);
+				}
+			} else {
+				valid = 1;
+				timersub(&expire, &now, &lt);
+				if (!timerisset(&next) ||
+				    timercmp(&next, &lt, >))
+					next = lt;
 			}
-		} else {
-			valid = 1;
-			timersub(&expire, &now, &lt);
-			if (!timerisset(&next) || timercmp(&next, &lt, >))
-				next = lt;
 		}
 
 		/* Addresses are expired in ipv6ns_probeaddrs
 		 * so that DHCPv6 addresses can be removed also. */
 		TAILQ_FOREACH_SAFE(rao, &rap->options, next, raon) {