zebra: netlink: grab blackhole list from kernel

support processing of RTM_BLACKHOLE et al. from kernel and dump them
into appropriate blackhole rib entries.

this exhibits the deletion bug famously fixed by Joakim Tjernlund, if
that patch isn't applied blackhole route deletion from kernel doesn't
work...

1 files changed, 40 insertions, 10 deletions

diff --git a/zebra/rt_netlink.c b/zebra/rt_netlink.c
index b29cb216..23acd5f3 100644
--- a/zebra/rt_netlink.c
+++ b/zebra/rt_netlink.c
@@ -85,6 +85,28 @@ extern struct zebra_privs_t zserv_privs;
 
 extern u_int32_t nl_rcvbufsize;
 
+/* dispatch rtm_type field, return 1 if we want to process this */
+static int
+get_discard_or_unicast (unsigned char rtm_type, unsigned *zflags)
+{
+  switch (rtm_type)
+    {
+    case RTN_UNICAST:
+      *zflags = 0;
+      return 1;
+    case RTN_UNREACHABLE:
+      *zflags = RIB_ZF_REJECT;
+      return 1;
+    case RTN_PROHIBIT:
+      *zflags = RIB_ZF_PROHIBIT;
+      return 1;
+    case RTN_BLACKHOLE:
+      *zflags = RIB_ZF_BLACKHOLE;
+      return 1;
+    }
+  return 0;
+}
+
 /* Note: on netlink systems, there should be a 1-to-1 mapping between interface
    names and ifindex values. */
 static void
@@ -648,6 +670,7 @@ netlink_routing_table (struct sockaddr_nl *snl, struct nlmsghdr *h)
   struct rtmsg *rtm;
   struct rtattr *tb[RTA_MAX + 1];
   u_char flags = 0;
+  unsigned discard = 0;
 
   char anyaddr[16] = { 0 };
 
@@ -663,7 +686,8 @@ netlink_routing_table (struct sockaddr_nl *snl, struct nlmsghdr *h)
 
   if (h->nlmsg_type != RTM_NEWROUTE)
     return 0;
-  if (rtm->rtm_type != RTN_UNICAST)
+
+  if (!get_discard_or_unicast (rtm->rtm_type, &discard))
     return 0;
 
   table = rtm->rtm_table;
@@ -724,7 +748,8 @@ netlink_routing_table (struct sockaddr_nl *snl, struct nlmsghdr *h)
       memcpy (&p.prefix, dest, 4);
       p.prefixlen = rtm->rtm_dst_len;
 
-      rib_add_ipv4 (ZEBRA_ROUTE_KERNEL, flags, &p, gate, src, index, table, metric, 0);
+      rib_add_ipv4 (ZEBRA_ROUTE_KERNEL, flags | (discard << 8), &p,
+		    gate, src, index, table, metric, 0);
     }
 #ifdef HAVE_IPV6
   if (rtm->rtm_family == AF_INET6)
@@ -734,8 +759,8 @@ netlink_routing_table (struct sockaddr_nl *snl, struct nlmsghdr *h)
       memcpy (&p.prefix, dest, 16);
       p.prefixlen = rtm->rtm_dst_len;
 
-      rib_add_ipv6 (ZEBRA_ROUTE_KERNEL, flags, &p, gate, index, table,
-		    metric, 0);
+      rib_add_ipv6 (ZEBRA_ROUTE_KERNEL, flags | (discard << 8), &p,
+		    gate, index, table, metric, 0);
     }
 #endif /* HAVE_IPV6 */
 
@@ -772,6 +797,7 @@ netlink_route_change (struct sockaddr_nl *snl, struct nlmsghdr *h)
   void *dest;
   void *gate;
   void *src;
+  unsigned discard = 0;
 
   rtm = NLMSG_DATA (h);
 
@@ -788,10 +814,10 @@ netlink_route_change (struct sockaddr_nl *snl, struct nlmsghdr *h)
                h->nlmsg_type ==
                RTM_NEWROUTE ? "RTM_NEWROUTE" : "RTM_DELROUTE",
                rtm->rtm_family == AF_INET ? "ipv4" : "ipv6",
-               rtm->rtm_type == RTN_UNICAST ? "unicast" : "multicast",
+               rtm->rtm_type == RTN_UNICAST ? "unicast" : "!unicast",
                lookup (rtproto_str, rtm->rtm_protocol));
 
-  if (rtm->rtm_type != RTN_UNICAST)
+  if (!get_discard_or_unicast (rtm->rtm_type, &discard))
     {
       return 0;
     }
@@ -862,9 +888,11 @@ netlink_route_change (struct sockaddr_nl *snl, struct nlmsghdr *h)
         }
 
       if (h->nlmsg_type == RTM_NEWROUTE)
-        rib_add_ipv4 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, src, index, table, 0, 0);
+        rib_add_ipv4 (ZEBRA_ROUTE_KERNEL, discard << 8, &p,
+		      gate, src, index, table, 0, 0);
       else
-        rib_delete_ipv4 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, index, table);
+        rib_delete_ipv4 (ZEBRA_ROUTE_KERNEL, discard << 8, &p,
+			 gate, index, table);
     }
 
 #ifdef HAVE_IPV6
@@ -890,9 +918,11 @@ netlink_route_change (struct sockaddr_nl *snl, struct nlmsghdr *h)
         }
 
       if (h->nlmsg_type == RTM_NEWROUTE)
-        rib_add_ipv6 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, index, table, 0, 0);
+        rib_add_ipv6 (ZEBRA_ROUTE_KERNEL, discard << 8, &p,
+		      gate, index, table, 0, 0);
       else
-        rib_delete_ipv6 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, index, table);
+        rib_delete_ipv6 (ZEBRA_ROUTE_KERNEL, discard << 8, &p,
+			 gate, index, table);
     }
 #endif /* HAVE_IPV6 */