RAdv: Support for more specific routes (RFC 4191)

The patch implements Default Router Preferences and More-Specific Routes
(RFC 4191) for RAdv protocol, allowing to announce router preference and
more specific routes in router advertisements. Routes can be exported to
RAdv like to regular routing protocols.

Some cleanups, bugfixes and other changes done by Ondrej Zajicek.

1 files changed, 57 insertions, 15 deletions

diff --git a/proto/radv/packets.c b/proto/radv/packets.c
index 8a301854..fbe02060 100644
--- a/proto/radv/packets.c
+++ b/proto/radv/packets.c
@@ -26,6 +26,7 @@ struct radv_ra_packet
 
 #define OPT_PREFIX	3
 #define OPT_MTU		5
+#define OPT_ROUTE	24
 #define OPT_RDNSS	25
 #define OPT_DNSSL	31
 
@@ -52,6 +53,15 @@ struct radv_opt_mtu
   u32 mtu;
 };
 
+struct radv_opt_route {
+  u8 type;
+  u8 length;
+  u8 pxlen;
+  u8 flags;
+  u32 lifetime;
+  u8 prefix[];
+};
+
 struct radv_opt_rdnss
 {
   u8 type;
@@ -71,6 +81,41 @@ struct radv_opt_dnssl
 };
 
 static int
+radv_prepare_route(struct radv_iface *ifa, struct radv_route *rt,
+		   char **buf, char *bufend)
+{
+  struct radv_proto *p = ifa->ra;
+  struct radv_config *cf = (void *) p->p.cf;
+  u8 px_blocks = (rt->n.pxlen + 63) / 64;
+  u8 opt_len = 8 * (1 + px_blocks);
+
+  if (*buf + opt_len > bufend)
+  {
+    log(L_WARN, "%s: Too many RA options on interface %s",
+	p->p.name, ifa->iface->name);
+    return -1;
+  }
+
+  struct radv_opt_route *opt = (void *) *buf;
+  *buf += opt_len;
+  opt->type = OPT_ROUTE;
+  opt->length = 1 + px_blocks;
+  opt->pxlen = rt->n.pxlen;
+  opt->flags = rt->preference;
+
+  if (p->valid && (p->active || !cf->route_lifetime_sensitive) && rt->alive)
+    opt->lifetime = htonl(rt->lifetime_set ? rt->lifetime : cf->route_lifetime);
+  else
+    opt->lifetime = 0;
+
+  /* Copy the relevant part of the prefix */
+  ip6_addr px_addr = ip6_hton(rt->n.prefix);
+  memcpy(opt->prefix, &px_addr, 8 * px_blocks);
+
+  return 0;
+}
+
+static int
 radv_prepare_rdnss(struct radv_iface *ifa, list *rdnss_list, char **buf, char *bufend)
 {
   struct radv_rdnss_config *rcf = HEAD(*rdnss_list);
@@ -252,7 +297,7 @@ radv_prepare_ra(struct radv_iface *ifa)
   pkt->code = 0;
   pkt->checksum = 0;
   pkt->current_hop_limit = ic->current_hop_limit;
-  pkt->router_lifetime = (p->active || !ic->default_lifetime_sensitive) ?
+  pkt->router_lifetime = (p->valid && (p->active || !ic->default_lifetime_sensitive)) ?
     htons(ic->default_lifetime) : 0;
   pkt->flags = (ic->managed ? OPT_RA_MANAGED : 0) |
     (ic->other_config ? OPT_RA_OTHER_CFG : 0) |
@@ -292,13 +337,23 @@ radv_prepare_ra(struct radv_iface *ifa)
   if (radv_prepare_dnssl(ifa, &ic->dnssl_list, &buf, bufend) < 0)
     goto done;
 
+  if (p->fib_up)
+  {
+    FIB_WALK(&p->routes, rt)
+    {
+      if (radv_prepare_route(ifa, (struct radv_route *) rt, &buf, bufend) < 0)
+	goto done;
+    }
+    FIB_WALK_END;
+  }
+
  done:
   ifa->plen = buf - bufstart;
 }
 
 
 void
-radv_send_ra(struct radv_iface *ifa, int shutdown)
+radv_send_ra(struct radv_iface *ifa)
 {
   struct radv_proto *p = ifa->ra;
 
@@ -306,19 +361,6 @@ radv_send_ra(struct radv_iface *ifa, int shutdown)
   if (!ifa->plen)
     radv_prepare_ra(ifa);
 
-  if (shutdown)
-  {
-    /*
-     * Modify router lifetime to 0, it is not restored because we suppose that
-     * the iface will be removed. The preference value also has to be zeroed.
-     * (RFC 4191 2.2: If router lifetime is 0, the preference value must be 0.)
-     */
-
-    struct radv_ra_packet *pkt = (void *) ifa->sk->tbuf;
-    pkt->router_lifetime = 0;
-    pkt->flags &= ~RA_PREF_MASK;
-  }
-
   RADV_TRACE(D_PACKETS, "Sending RA via %s", ifa->iface->name);
   sk_send_to(ifa->sk, ifa->plen, IP6_ALL_NODES, 0);
 }