Workaround an issue on BSD where the kernel pretends a freshly added address is from...

See comments in the changeset for more details.

diff --git a/if-bsd.c b/if-bsd.c
index f6fb036cecc4baa29f6b7b5a9c9e494dbf5f91b2..3a91a49d7f3d0f0d77b091005f014c27c6503290 100644 (file)
--- a/if-bsd.c
+++ b/if-bsd.c
@@ -909,6 +909,8 @@ if_address6(unsigned char cmd, const struct ipv6_addr *ia)
        struct in6_addr mask;
        struct priv *priv;
 
+       priv = (struct priv *)ia->iface->ctx->priv;
+
        memset(&ifa, 0, sizeof(ifa));
        strlcpy(ifa.ifra_name, ia->iface->name, sizeof(ifa.ifra_name));
        /*
@@ -938,11 +940,41 @@ if_address6(unsigned char cmd, const struct ipv6_addr *ia)
        ifa_scope(&ifa.ifra_addr, ia->iface->index);
        ipv6_mask(&mask, ia->prefix_len);
        ADDADDR(&ifa.ifra_prefixmask, &mask);
+
+       /*
+        * Every BSD kernel wants to add the prefix of the address to it's
+        * list of RA received prefixes.
+        * THIS IS WRONG because there (as the comments in the kernel state)
+        * is no API for managing prefix lifetime and the kernel should not
+        * pretend it's from a RA either.
+        *
+        * The issue is that the very first assigned prefix will inherit the
+        * lifetime of the address, but any subsequent alteration of the
+        * address OR it's lifetime will not affect the prefix lifetime.
+        * As such, we cannot stop the prefix from timing out and then
+        * constantly removing the prefix route dhcpcd is capable of adding
+        * in it's absense.
+        *
+        * What we can do to mitigate the issue is to add the adress with
+        * infinite lifetimes, so the prefix route will never time out.
+        * Once done, we can then set lifetimes on the address and all is good.
+        * The downside of this approach is that we need to manually remove
+        * the kernel route because it has no lifetime, but this is OK as
+        * dhcpcd will handle this too.
+        *
+        * This issue is discussed on the NetBSD mailing lists here:
+        * http://mail-index.netbsd.org/tech-net/2016/08/05/msg006044.html
+        */
+       if (cmd == RTM_NEWADDR && !(ia->flags & IPV6_AF_ADDED)) {
+               ifa.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
+               ifa.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;
+               (void)ioctl(priv->pf_inet6_fd, SIOCAIFADDR_IN6, &ifa);
+       }
+
        ifa.ifra_lifetime.ia6t_vltime = ia->prefix_vltime;
        ifa.ifra_lifetime.ia6t_pltime = ia->prefix_pltime;
 #undef ADDADDR
 
-       priv = (struct priv *)ia->iface->ctx->priv;
        return ioctl(priv->pf_inet6_fd,
            cmd == RTM_DELADDR ? SIOCDIFADDR_IN6 : SIOCAIFADDR_IN6, &ifa);
 }