fabricd: add option to treat dummy interfaces as loopback interfaces

Enable dummy-interfaces to be used as router-id interfaces in openfabric
networks. This allows multiple openfabric routers with different
router-ids on a single node when using IP unnumbered setup (interfaces
without IPs configured). Previously we were limited by having a single
loopback interface, allowing only one openfabric router per node.

Signed-off-by: Gabriel Goller <g.goller@proxmox.com>

doc/manpages/frr-fabricd.rst

@@ -21,6 +21,10 @@ OPTIONS available for the |DAEMON| command:
 
 .. include:: common-options.rst
 
+.. option:: --dummy_as_loopback
+
+   Treat dummy interfaces as loopback interfaces.
+
 FILES
 =====
 

doc/user/fabricd.rst

@@ -15,11 +15,18 @@ FRR implements OpenFabric in a daemon called *fabricd*
 Configuring fabricd
 ===================
 
-There are no *fabricd* specific options. Common options can be specified
-(:ref:`common-invocation-options`) to *fabricd*. *fabricd* needs to acquire
-interface information from *zebra* in order to function. Therefore *zebra* must
-be running before invoking *fabricd*. Also, if *zebra* is restarted then *fabricd*
-must be too.
+*fabricd* accepts all common invocations (:ref:`common-invocation-options`) and
+the following specific options.
+
+.. program:: fabricd
+
+.. option:: --dummy_as_loopback
+
+   Treat dummy interfaces as loopback interfaces.
+
+*fabricd* needs to acquire interface information from *zebra* in order to
+function. Therefore *zebra* must be running before invoking *fabricd*. Also, if
+*zebra* is restarted then *fabricd* must be too.
 
 Like other daemons, *fabricd* configuration is done in an OpenFabric specific
 configuration file :file:`fabricd.conf`.

isisd/isis_circuit.c

@@ -491,16 +491,17 @@ void isis_circuit_if_add(struct isis_circuit *circuit, struct interface *ifp)
 {
 	struct connected *conn;
 
-	if (if_is_broadcast(ifp)) {
+	if (if_is_loopback(ifp) || (isis_option_check(ISIS_OPT_DUMMY_AS_LOOPBACK) &&
+				    CHECK_FLAG(ifp->status, ZEBRA_INTERFACE_DUMMY))) {
+		circuit->circ_type = CIRCUIT_T_LOOPBACK;
+		circuit->is_passive = 1;
+	} else if (if_is_broadcast(ifp)) {
 		if (fabricd || circuit->circ_type_config == CIRCUIT_T_P2P)
 			circuit->circ_type = CIRCUIT_T_P2P;
 		else
 			circuit->circ_type = CIRCUIT_T_BROADCAST;
 	} else if (if_is_pointopoint(ifp)) {
 		circuit->circ_type = CIRCUIT_T_P2P;
-	} else if (if_is_loopback(ifp)) {
-		circuit->circ_type = CIRCUIT_T_LOOPBACK;
-		circuit->is_passive = 1;
 	} else {
 		/* It's normal in case of loopback etc. */
 		if (IS_DEBUG_EVENTS)

isisd/isis_main.c

@@ -80,9 +80,12 @@ struct zebra_privs_t isisd_privs = {
 	.cap_num_p = array_size(_caps_p),
 	.cap_num_i = 0};
 
+#define OPTION_DUMMY_AS_LOOPBACK 2000
+
 /* isisd options */
 static const struct option longopts[] = {
 	{"int_num", required_argument, NULL, 'I'},
+	{"dummy_as_loopback", no_argument, NULL, OPTION_DUMMY_AS_LOOPBACK},
 	{0}};
 
 /* Master of threads. */
@@ -269,15 +272,16 @@ int main(int argc, char **argv, char **envp)
 {
 	int opt;
 	int instance = 1;
+	bool dummy_as_loopback = false;
 
 #ifdef FABRICD
 	frr_preinit(&fabricd_di, argc, argv);
 #else
 	frr_preinit(&isisd_di, argc, argv);
 #endif
-	frr_opt_add(
-		"I:", longopts,
-		"  -I, --int_num      Set instance number (label-manager)\n");
+	frr_opt_add("I:", longopts,
+		"  -I, --int_num		Set instance number (label-manager).\n"
+		"      --dummy_as_loopback      Treat dummy interfaces like loopback interfaces.\n");
 
 	/* Command line argument treatment. */
 	while (1) {
@@ -295,6 +299,9 @@ int main(int argc, char **argv, char **envp)
 				zlog_err("Instance %i out of range (1..%u)",
 					 instance, (unsigned short)-1);
 			break;
+		case OPTION_DUMMY_AS_LOOPBACK:
+			dummy_as_loopback = true;
+			break;
 		default:
 			frr_help_exit(1);
 		}
@@ -311,6 +318,9 @@ int main(int argc, char **argv, char **envp)
 	/* thread master */
 	isis_master_init(frr_init());
 	master = im->master;
+	if (dummy_as_loopback)
+		isis_option_set(ISIS_OPT_DUMMY_AS_LOOPBACK);
+
 	/*
 	 *  initializations
 	 */

isisd/isisd.c

@@ -116,6 +116,25 @@ int show_isis_neighbor_common(struct vty *, struct json_object *json,
 int clear_isis_neighbor_common(struct vty *, const char *id,
 			       const char *vrf_name, bool all_vrf);
 
+
+/* ISIS global flag manipulation.  */
+int isis_option_set(int flag)
+{
+	switch (flag) {
+	case ISIS_OPT_DUMMY_AS_LOOPBACK:
+		SET_FLAG(im->options, flag);
+		break;
+	default:
+		return -1;
+	}
+	return 0;
+}
+
+int isis_option_check(int flag)
+{
+	return CHECK_FLAG(im->options, flag);
+}
+
 /* Link ISIS instance to VRF. */
 void isis_vrf_link(struct isis *isis, struct vrf *vrf)
 {

isisd/isisd.h

@@ -74,7 +74,9 @@ struct isis_master {
 	struct list *isis;
 	/* ISIS thread master. */
 	struct event_loop *master;
+	/* Various global options */
 	uint8_t options;
+#define ISIS_OPT_DUMMY_AS_LOOPBACK (1 << 0)
 };
 #define F_ISIS_UNIT_TEST 0x01
 
@@ -269,6 +271,8 @@ DECLARE_HOOK(isis_area_overload_bit_update, (struct isis_area * area), (area));
 void isis_terminate(void);
 void isis_master_init(struct event_loop *master);
 void isis_master_terminate(void);
+int isis_option_set(int flag);
+int isis_option_check(int flag);
 void isis_vrf_link(struct isis *isis, struct vrf *vrf);
 void isis_vrf_unlink(struct isis *isis, struct vrf *vrf);
 struct isis *isis_lookup_by_vrfid(vrf_id_t vrf_id);