zebra: check at startup if the kernel supports MPLS

Replace all HAVE_MPLS #ifdef's by a run-time check if MPLS is supported
by the kernel or not. This way we don't need to create multiple packages
for each OS distribution.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

configure.ac

@@ -309,8 +309,6 @@ AC_ARG_ENABLE(systemd,
   AS_HELP_STRING([--enable-systemd], [enable Systemd support]))
 AC_ARG_ENABLE(poll,
   AS_HELP_STRING([--enable-poll], [enable usage of Poll instead of select]))
-AC_ARG_ENABLE(mpls,
-  AS_HELP_STRING([--enable-mpls], [enable MPLS support - requires compatible kernel]))
 AC_ARG_ENABLE(werror,
   AS_HELP_STRING([--enable-werror], [enable -Werror (recommended for developers only)]))
 AC_ARG_ENABLE(cumulus,
@@ -367,27 +365,20 @@ dnl MPLS check
 dnl ----------
 MPLS_METHOD=""
 AC_MSG_CHECKING(whether this OS has MPLS stack)
-if test "x${enable_mpls}" = "xyes"; then
-  case "$host" in
-    *-linux*)
-        AC_DEFINE(HAVE_MPLS,,Enable MPLS)
-        MPLS_METHOD="zebra_mpls_netlink.o"
-        AC_MSG_RESULT(Linux MPLS)
-    ;;
-    *-openbsd*)
-        AC_DEFINE(HAVE_MPLS,,Enable MPLS)
-        MPLS_METHOD="zebra_mpls_openbsd.o"
-        AC_MSG_RESULT(OpenBSD MPLS)
-    ;;
-    *)
-        AC_MSG_RESULT(Unsupported kernel)
-        MPLS_METHOD="zebra_mpls_null.o"
-    ;;
-  esac
-else
-  AC_MSG_RESULT(disabled)
-  MPLS_METHOD="zebra_mpls_null.o"
-fi
+case "$host" in
+  *-linux*)
+      MPLS_METHOD="zebra_mpls_netlink.o"
+      AC_MSG_RESULT(Linux MPLS)
+  ;;
+  *-openbsd*)
+      MPLS_METHOD="zebra_mpls_openbsd.o"
+      AC_MSG_RESULT(OpenBSD MPLS)
+  ;;
+  *)
+      MPLS_METHOD="zebra_mpls_null.o"
+      AC_MSG_RESULT(Unsupported kernel)
+  ;;
+esac
 AC_SUBST(MPLS_METHOD)
 
 if test "${enable_cumulus}" = "yes" ; then

lib/sockunion.h

@@ -25,7 +25,7 @@
 
 #include "privs.h"
 #include "if.h"
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
 #include <netmpls/mpls.h>
 #endif
 
@@ -34,7 +34,7 @@ union sockunion
   struct sockaddr sa;
   struct sockaddr_in sin;
   struct sockaddr_in6 sin6;
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
   struct sockaddr_mpls smpls;
 #endif
 };

zebra/kernel_socket.c

@@ -21,7 +21,7 @@
 
 #include <zebra.h>
 #include <net/if_types.h>
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
 #include <netmpls/mpls.h>
 #endif
 
@@ -1101,7 +1101,7 @@ rtm_write (int message,
   msg.rtm.rtm_addrs = RTA_DST;
   msg.rtm.rtm_addrs |= RTA_GATEWAY;
   msg.rtm.rtm_flags = RTF_UP;
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
   msg.rtm.rtm_flags |= RTF_MPATH;
   msg.rtm.rtm_fmask = RTF_MPLS;
 #endif
@@ -1150,7 +1150,7 @@ rtm_write (int message,
   else if (message == RTM_ADD) 
     msg.rtm.rtm_flags |= RTF_HOST;
 
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
   if (mpls)
     {
       msg.rtm.rtm_addrs |= RTA_SRC;
@@ -1185,7 +1185,7 @@ rtm_write (int message,
   SOCKADDRSET (dest, RTA_DST);
   SOCKADDRSET (gate, RTA_GATEWAY);
   SOCKADDRSET (mask, RTA_NETMASK);
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
   SOCKADDRSET (mpls, RTA_SRC);
 #endif
 

zebra/main.c

@@ -350,9 +350,6 @@ main (int argc, char **argv)
   zebra_debug_init ();
   router_id_cmd_init ();
   zebra_vty_init ();
-#if defined(HAVE_MPLS)
-  zebra_mpls_vty_init ();
-#endif
   access_list_init ();
   prefix_list_init ();
 #if defined (HAVE_RTADV)
@@ -367,6 +364,7 @@ main (int argc, char **argv)
 #endif
 
   zebra_mpls_init ();
+  zebra_mpls_vty_init ();
 
   /* For debug purpose. */
   /* SET_FLAG (zebra_debug_event, ZEBRA_DEBUG_EVENT); */

zebra/rt.h

@@ -44,6 +44,6 @@ extern int kernel_delete_ipv6 (struct prefix *, struct rib *);
 extern int kernel_add_lsp (zebra_lsp_t *);
 extern int kernel_upd_lsp (zebra_lsp_t *);
 extern int kernel_del_lsp (zebra_lsp_t *);
-extern void mpls_kernel_init (void);
+extern int mpls_kernel_init (void);
 
 #endif /* _ZEBRA_RT_H */

zebra/rt_socket.c

@@ -21,7 +21,7 @@
  */
 
 #include <zebra.h>
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
 #include <netmpls/mpls.h>
 #endif
 
@@ -78,7 +78,7 @@ kernel_rtm_ipv4 (int cmd, struct prefix *p, struct rib *rib, int family)
 {
   struct sockaddr_in *mask = NULL;
   struct sockaddr_in sin_dest, sin_mask, sin_gate;
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
   struct sockaddr_mpls smpls;
 #endif
   union sockunion *smplsp = NULL;
@@ -156,7 +156,7 @@ kernel_rtm_ipv4 (int cmd, struct prefix *p, struct rib *rib, int family)
 	      mask = &sin_mask;
 	    }
 
-#if defined HAVE_MPLS && defined __OpenBSD__
+#ifdef __OpenBSD__
 	  if (nexthop->nh_label)
 	    {
 	      memset (&smpls, 0, sizeof (smpls));

zebra/zebra_mpls.c

@@ -53,6 +53,8 @@ DEFINE_MTYPE_STATIC(ZEBRA, NHLFE,		"MPLS nexthop object")
 DEFINE_MTYPE_STATIC(ZEBRA, SNHLFE,		"MPLS static nexthop object")
 DEFINE_MTYPE_STATIC(ZEBRA, SNHLFE_IFNAME,	"MPLS static nexthop ifname")
 
+int mpls_enabled;
+
 /* Default rtm_table for all clients */
 extern struct zebra_t zebrad;
 
@@ -1902,6 +1904,12 @@ zebra_mpls_init_tables (struct zebra_vrf *zvrf)
 void
 zebra_mpls_init (void)
 {
-  mpls_kernel_init ();
+  if (mpls_kernel_init () < 0)
+    {
+      zlog_warn ("Disabling MPLS support (no kernel support)");
+      return;
+    }
+
+  mpls_enabled = 1;
   mpls_processq_init (&zebrad);
 }

zebra/zebra_mpls.h

@@ -292,6 +292,12 @@ zebra_mpls_init_tables (struct zebra_vrf *zvrf);
 void
 zebra_mpls_init (void);
 
+/*
+ * MPLS VTY.
+ */
+void
+zebra_mpls_vty_init (void);
+
 /* Inline functions. */
 
 /*
@@ -364,4 +370,7 @@ mpls_should_lsps_be_processed(struct zebra_vrf *zvrf)
   return ((zvrf->mpls_flags & MPLS_FLAG_SCHEDULE_LSPS) ? 1 : 0);
 }
 
+/* Global variables. */
+extern int mpls_enabled;
+
 #endif /*_ZEBRA_MPLS_H */

zebra/zebra_mpls_netlink.c

@@ -77,4 +77,16 @@ kernel_del_lsp (zebra_lsp_t *lsp)
   return 0;
 }
 
-void mpls_kernel_init (void) {};
+int
+mpls_kernel_init (void)
+{
+  struct stat st;
+
+  /*
+   * Check if the MPLS module is loaded in the kernel.
+   */
+  if (stat ("/proc/sys/net/mpls", &st) != 0)
+    return -1;
+
+  return 0;
+};

zebra/zebra_mpls_null.c

@@ -5,4 +5,4 @@
 int kernel_add_lsp (zebra_lsp_t *lsp) { return 0; }
 int kernel_upd_lsp (zebra_lsp_t *lsp) { return 0; }
 int kernel_del_lsp (zebra_lsp_t *lsp) { return 0; }
-void mpls_kernel_init (void) {};
+int mpls_kernel_init (void) { return -1; };

zebra/zebra_mpls_openbsd.c

@@ -178,15 +178,15 @@ kernel_del_lsp (zebra_lsp_t *lsp)
 }
 
 #define MAX_RTSOCK_BUF	128 * 1024
-void
+int
 mpls_kernel_init (void)
 {
   int		rcvbuf, default_rcvbuf;
   socklen_t	optlen;
 
   if ((kr_state.fd = socket(AF_ROUTE, SOCK_RAW, 0)) == -1) {
-      zlog_warn("kr_init: socket");
-      return;
+      zlog_warn("%s: socket", __func__);
+      return -1;
   }
 
   /* grow receive buffer, don't wanna miss messages */
@@ -203,4 +203,6 @@ mpls_kernel_init (void)
       ;	/* nothing */
 
   kr_state.rtseq = 1;
+
+  return 0;
 }

zebra/zebra_mpls_vty.c

@@ -21,8 +21,6 @@
 
 #include <zebra.h>
 
-#if defined(HAVE_MPLS)
-
 #include "memory.h"
 #include "if.h"
 #include "prefix.h"
@@ -810,6 +808,18 @@ DEFUN (show_mpls_table_lsp,
   return CMD_SUCCESS;
 }
 
+DEFUN (show_mpls_status,
+       show_mpls_status_cmd,
+       "show mpls status",
+       SHOW_STR
+       "MPLS information\n"
+       "MPLS status\n")
+{
+  vty_out (vty, "MPLS support enabled: %s%s", (mpls_enabled) ? "yes" :
+	   "no (mpls kernel extensions not detected)", VTY_NEWLINE);
+  return CMD_SUCCESS;
+}
+
 /* MPLS node for MPLS LSP. */
 static struct cmd_node mpls_node = { MPLS_NODE,  "",  1 };
 
@@ -817,6 +827,12 @@ static struct cmd_node mpls_node = { MPLS_NODE,  "",  1 };
 void
 zebra_mpls_vty_init (void)
 {
+  install_element (VIEW_NODE, &show_mpls_status_cmd);
+  install_element (ENABLE_NODE, &show_mpls_status_cmd);
+
+  if (! mpls_enabled)
+    return;
+
   install_node (&mpls_node, zebra_mpls_config);
 
   install_element (CONFIG_NODE, &ip_route_label_cmd);
@@ -863,5 +879,3 @@ zebra_mpls_vty_init (void)
   install_element (VIEW_NODE, &show_mpls_table_lsp_cmd);
   install_element (ENABLE_NODE, &show_mpls_table_lsp_cmd);
 }
-
-#endif /* HAVE_MPLS */

zebra/zserv.c

@@ -1676,6 +1676,9 @@ zread_mpls_labels (int command, struct zserv *client, u_short length,
   in_label = stream_getl (s);
   out_label = stream_getl (s);
 
+  if (! mpls_enabled)
+    return;
+
   if (command == ZEBRA_MPLS_LABELS_ADD)
     {
       mpls_lsp_install (zvrf, type, in_label, out_label, gtype, &gate,

zebra/zserv.h

@@ -149,9 +149,6 @@ extern void kernel_terminate (struct zebra_ns *);
 extern void zebra_route_map_init (void);
 extern void zebra_snmp_init (void);
 extern void zebra_vty_init (void);
-#if defined(HAVE_MPLS)
-extern void zebra_mpls_vty_init (void);
-#endif
 
 extern int zsend_vrf_add (struct zserv *, struct zebra_vrf *);
 extern int zsend_vrf_delete (struct zserv *, struct zebra_vrf *);