Our first Netlink syncer!

Add lcpng_nl_sync.c that will house these functions. Their purpose is to
take state learned from netlink messages, and apply that state to VPP.

Some rearranging/plumbing was necessary to get logging to be visible in
this new source file.

Then, we add lcp_nl_neigh_add() and _del() which look up the LIP, convert
the lladdr and ip address from Netlink into VPP variants, and then add or
remove the ip4/ip6 neighbor adjacency.

CMakeLists.txt

@@ -56,6 +56,7 @@ add_vpp_plugin(lcpng_if
 add_vpp_plugin(lcpng_nl
   SOURCES
   lcpng_netlink.c
+  lcpng_nl_sync.c
 
   LINK_LIBRARIES
   lcpng

lcpng_netlink.c

@@ -40,7 +40,10 @@
 #include <plugins/lcpng/lcpng_netlink.h>
 #include <plugins/lcpng/lcpng_interface.h>
 
-static lcp_nl_main_t lcp_nl_main = {
+static void lcp_nl_open_socket (u8 *ns);
+static void lcp_nl_close_socket (void);
+
+lcp_nl_main_t lcp_nl_main = {
   .rx_buf_size = NL_RX_BUF_SIZE_DEF,
   .tx_buf_size = NL_TX_BUF_SIZE_DEF,
   .batch_size = NL_BATCH_SIZE_DEF,
@@ -200,6 +203,10 @@ lcp_nl_dispatch (struct nl_object *obj, void *arg)
   /* Here is where we'll sync the netlink messages into VPP */
   switch (nl_object_get_msgtype (obj))
     {
+    case RTM_NEWNEIGH:
+      return lcp_nl_neigh_add ((struct rtnl_neigh *) obj);
+    case RTM_DELNEIGH:
+      return lcp_nl_neigh_del ((struct rtnl_neigh *) obj);
     default:
       NL_WARN ("dispatch: ignored %U", format_nl_object, obj);
       break;

lcpng_netlink.h

@@ -75,12 +75,15 @@ typedef struct lcp_nl_main
   u32 batch_delay_ms;
 
 } lcp_nl_main_t;
-
+extern lcp_nl_main_t lcp_nl_main;
-static void lcp_nl_open_socket (u8 *ns);
-static void lcp_nl_close_socket (void);
 
 u8 *format_nl_object (u8 *s, va_list *args);
 
+/* Functions from lcpng_nl_sync.c
+ */
+void lcp_nl_neigh_add (struct rtnl_neigh *rn);
+void lcp_nl_neigh_del (struct rtnl_neigh *rn);
+
 /*
  * fd.io coding-style-patch-verification: ON
  *

lcpng_nl_sync.c

@@ -0,0 +1,138 @@
+/* Hey Emacs use -*- mode: C -*- */
+/*
+ * Copyright 2021 Cisco and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <sys/socket.h>
+#include <linux/if.h>
+
+#include <vnet/vnet.h>
+#include <vnet/plugin/plugin.h>
+
+#include <vppinfra/linux/netns.h>
+
+#include <plugins/lcpng/lcpng_interface.h>
+#include <plugins/lcpng/lcpng_netlink.h>
+
+#include <vnet/fib/fib_table.h>
+#include <vnet/mfib/mfib_table.h>
+#include <vnet/ip/ip6_ll_table.h>
+#include <vnet/ip-neighbor/ip_neighbor.h>
+#include <vnet/ip/ip6_link.h>
+
+#ifndef NUD_VALID
+#define NUD_VALID                                                             \
+  (NUD_PERMANENT | NUD_NOARP | NUD_REACHABLE | NUD_PROBE | NUD_STALE |        \
+   NUD_DELAY)
+#endif
+
+static void
+lcp_nl_mk_ip_addr (const struct nl_addr *rna, ip_address_t *ia)
+{
+  ip_address_reset (ia);
+  ip_address_set (ia, nl_addr_get_binary_addr (rna),
+		  nl_addr_get_family (rna) == AF_INET6 ? AF_IP6 : AF_IP4);
+}
+
+static void
+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));
+}
+
+void
+lcp_nl_neigh_add (struct rtnl_neigh *rn)
+{
+  lcp_itf_pair_t *lip;
+  struct nl_addr *ll;
+  ip_address_t nh;
+  int state;
+
+  NL_DBG ("neigh_add: netlink %U", format_nl_object, rn);
+
+  if (!(lip = lcp_itf_pair_get (
+	  lcp_itf_pair_find_by_vif (rtnl_neigh_get_ifindex (rn)))))
+    {
+      NL_WARN ("neigh_add: no LCP for %U ", format_nl_object, rn);
+      return;
+    }
+
+  lcp_nl_mk_ip_addr (rtnl_neigh_get_dst (rn), &nh);
+  ll = rtnl_neigh_get_lladdr (rn);
+  state = rtnl_neigh_get_state (rn);
+
+  if (ll && (state & NUD_VALID))
+    {
+      mac_address_t mac;
+      ip_neighbor_flags_t flags;
+      int rv;
+
+      lcp_nl_mk_mac_addr (ll, &mac);
+
+      if (state & (NUD_NOARP | NUD_PERMANENT))
+	flags = IP_NEIGHBOR_FLAG_STATIC;
+      else
+	flags = IP_NEIGHBOR_FLAG_DYNAMIC;
+
+      rv = ip_neighbor_add (&nh, &mac, lip->lip_phy_sw_if_index, flags, NULL);
+
+      if (rv)
+	{
+	  NL_ERROR ("neigh_add: Failed %U lladdr %U iface %U",
+		    format_ip_address, &nh, format_mac_address, &mac,
+		    format_vnet_sw_if_index_name, vnet_get_main (),
+		    lip->lip_phy_sw_if_index);
+	}
+      else
+	{
+	  NL_NOTICE ("neigh_add: Added %U lladdr %U iface %U",
+		     format_ip_address, &nh, format_mac_address, &mac,
+		     format_vnet_sw_if_index_name, vnet_get_main (),
+		     lip->lip_phy_sw_if_index);
+	}
+    }
+}
+
+void
+lcp_nl_neigh_del (struct rtnl_neigh *rn)
+{
+  ip_address_t nh;
+  int rv;
+  NL_DBG ("neigh_del: netlink %U", format_nl_object, rn);
+
+  lcp_itf_pair_t *lip;
+  if (!(lip = lcp_itf_pair_get (
+	  lcp_itf_pair_find_by_vif (rtnl_neigh_get_ifindex (rn)))))
+    {
+      NL_WARN ("neigh_del: no LCP for %U ", format_nl_object, rn);
+      return;
+    }
+
+  lcp_nl_mk_ip_addr (rtnl_neigh_get_dst (rn), &nh);
+  rv = ip_neighbor_del (&nh, lip->lip_phy_sw_if_index);
+
+  if (rv)
+    {
+      NL_ERROR ("neigh_del: Failed %U iface %U", format_ip_address, &nh,
+		format_vnet_sw_if_index_name, vnet_get_main (),
+		lip->lip_phy_sw_if_index);
+    }
+  else
+    {
+      NL_NOTICE ("neigh_del: Deleted %U iface %U", format_ip_address, &nh,
+		 format_vnet_sw_if_index_name, vnet_get_main (),
+		 lip->lip_phy_sw_if_index);
+    }
+}