Add newlink/delink processing.

- Can up/down a link.
- Can set MAC on a link, if it's a phy.
- Can set MTU on a link.
- Can delete link (including phy).

Because link state and mtu changes tend to go around in circles (from
netlink -> vpp; and then with lcp-sync on, as well from vpp -> netlink)
when we consume a batch of netlink messages, we'll temporarily turn off
lcp-sync if it's enabled.

TODO (in the next commit), the whole nine yards of creating interfaces
in VPP based on NEWLINK vlans that come in. Conceptualy not too
difficult: if NEWLINK doesn't have a LIP associated with it, but it's a
VLAN, and the parent of the VLAN is a link which _does_ have a LIP, then
we can create the subint in VPP in the correct way.

lcpng_nl_sync.c

@@ -52,6 +52,168 @@ lcp_nl_mk_mac_addr (const struct nl_addr *rna, mac_address_t *mac)
   mac_address_from_bytes (mac, nl_addr_get_binary_addr (rna));
 }
 
+/*
+ * Check timestamps on netlink message and interface pair to decide whether
+ * the message should be applied. See the declaration of nl_msg_info_t for
+ * an explanation on why this is necessary.
+ * If timestamps are good (message ts is newer than intf pair ts), return 0.
+ * Else, return -1.
+ */
+static int
+lcp_nl_lip_ts_check (nl_msg_info_t *msg_info, lcp_itf_pair_t *lip)
+{
+  if (msg_info->ts > lip->lip_create_ts)
+    return 0;
+
+  NL_DBG ("lip_ts_check: Early message for %U", format_lcp_itf_pair, lip);
+  return -1;
+}
+
+void
+lcp_nl_link_del (struct rtnl_link *rl)
+{
+  lcp_itf_pair_t *lip;
+
+  NL_DBG ("link_del: netlink %U", format_nl_object, rl);
+
+  if (!(lip = lcp_itf_pair_get (
+	  lcp_itf_pair_find_by_vif (rtnl_link_get_ifindex (rl)))))
+    {
+      NL_WARN ("link_del: no LCP for %U ", format_nl_object, rl);
+      return;
+    }
+
+  NL_NOTICE ("link_del: Removing %U", format_lcp_itf_pair, lip);
+  vlib_worker_thread_barrier_sync (vlib_get_main ());
+  lcp_itf_pair_delete (lip->lip_phy_sw_if_index);
+  vlib_worker_thread_barrier_release (vlib_get_main ());
+
+  if (rtnl_link_is_vlan (rl))
+    {
+      NL_NOTICE ("link_del: Removing subint %U", format_vnet_sw_if_index_name,
+		 vnet_get_main (), lip->lip_phy_sw_if_index);
+      vlib_worker_thread_barrier_sync (vlib_get_main ());
+      vnet_delete_sub_interface (lip->lip_phy_sw_if_index);
+      vnet_delete_sub_interface (lip->lip_host_sw_if_index);
+      vlib_worker_thread_barrier_release (vlib_get_main ());
+    }
+
+  return;
+}
+
+static void
+lcp_nl_link_set_mtu (struct rtnl_link *rl, lcp_itf_pair_t *lip)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 mtu;
+  vnet_sw_interface_t *sw;
+  vnet_hw_interface_t *hw;
+
+  mtu = rtnl_link_get_mtu (rl);
+  if (!mtu)
+    return;
+
+  sw = vnet_get_sw_interface (vnm, lip->lip_phy_sw_if_index);
+  hw = vnet_get_sup_hw_interface (vnm, lip->lip_phy_sw_if_index);
+  if (!sw || !hw)
+    return;
+
+  /* Set the MTU on the TAP and sw */
+  vnet_sw_interface_set_mtu (vnm, lip->lip_host_sw_if_index, mtu);
+  vnet_sw_interface_set_mtu (vnm, lip->lip_phy_sw_if_index, mtu);
+}
+
+static void
+lcp_nl_link_set_lladdr (struct rtnl_link *rl, lcp_itf_pair_t *lip)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  struct nl_addr *mac_addr;
+  vnet_sw_interface_t *sw;
+  vnet_hw_interface_t *hw;
+  void *mac_addr_bytes;
+
+  mac_addr = rtnl_link_get_addr (rl);
+  if (!mac_addr || (nl_addr_get_family (mac_addr) != AF_LLC))
+    return;
+
+  sw = vnet_get_sw_interface (vnm, lip->lip_phy_sw_if_index);
+  hw = vnet_get_sup_hw_interface (vnm, lip->lip_phy_sw_if_index);
+  if (!sw || !hw)
+    return;
+
+  /* can only change address on hw interface */
+  if (sw->sw_if_index != sw->sup_sw_if_index)
+    return;
+  /* can only change if there's an address present */
+  if (!vec_len (hw->hw_address))
+    return;
+
+  mac_addr_bytes = nl_addr_get_binary_addr (mac_addr);
+  if (clib_memcmp (mac_addr_bytes, hw->hw_address, nl_addr_get_len (mac_addr)))
+    vnet_hw_interface_change_mac_address (vnm, hw->hw_if_index,
+					  mac_addr_bytes);
+
+  /* mcast adjacencies need to be updated */
+  vnet_update_adjacency_for_sw_interface (vnm, lip->lip_phy_sw_if_index,
+					  lip->lip_phy_adjs.adj_index[AF_IP4]);
+  vnet_update_adjacency_for_sw_interface (vnm, lip->lip_phy_sw_if_index,
+					  lip->lip_phy_adjs.adj_index[AF_IP6]);
+}
+
+void
+lcp_nl_link_add (struct rtnl_link *rl, void *ctx)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  lcp_itf_pair_t *lip;
+  int admin_state;
+
+  NL_DBG ("link_add: netlink %U", format_nl_object, rl);
+
+  if (!(lip = lcp_itf_pair_get (
+	  lcp_itf_pair_find_by_vif (rtnl_link_get_ifindex (rl)))))
+    {
+      NL_WARN ("link_add: no LCP for %U (see TODO in code)", format_nl_object,
+	       rl);
+      // TODO(pim) -- here's where auto-creation of sub-int's comes into play
+      // if this is a nelink vlan interface, its parent may have a LIP, and if
+      // so, we can auto-create in VPP.
+      return;
+    }
+
+  if (lcp_nl_lip_ts_check ((nl_msg_info_t *) ctx, lip))
+    return;
+
+  // 0 == unknown; 2 == down; 6 == up; TODO(pim) figure out operstate values
+  /*
+  if (2 == rtnl_link_get_operstate(rl)) {
+      NL_WARN ("link_add: ignoring %U (wrong operstate)", format_nl_object,
+  rl); return;
+  }
+  */
+
+  admin_state = (IFF_UP & rtnl_link_get_flags (rl));
+  vlib_worker_thread_barrier_sync (vlib_get_main ());
+  if (admin_state)
+    {
+      vnet_sw_interface_admin_up (vnm, lip->lip_host_sw_if_index);
+      vnet_sw_interface_admin_up (vnm, lip->lip_phy_sw_if_index);
+    }
+  else
+    {
+      vnet_sw_interface_admin_down (vnm, lip->lip_phy_sw_if_index);
+      vnet_sw_interface_admin_down (vnm, lip->lip_host_sw_if_index);
+    }
+
+  lcp_nl_link_set_mtu (rl, lip);
+  lcp_nl_link_set_lladdr (rl, lip);
+  vlib_worker_thread_barrier_release (vlib_get_main ());
+
+  NL_NOTICE ("link_add: %U admin %s", format_lcp_itf_pair, lip,
+	     admin_state ? "up" : "down");
+
+  return;
+}
+
 static const mfib_prefix_t ip4_specials[] = {
   /* ALL prefixes are in network order */
   {