From 2bec04472aff8f3ea121152e52d06540800f6e4a Mon Sep 17 00:00:00 2001
From: Karen Schoener <karen@volta.io>
Date: Fri, 30 Oct 2020 17:46:32 -0400
Subject: [PATCH] isisd: if IS-IS is configured for v6, prefer v6 bfd sessions

Signed-off-by: Lynne Morrison <lynne@voltanet.io>
Signed-off-by: Karen Schoener <karen@voltanet.io>
---
 isisd/isis_adjacency.h |  1 +
 isisd/isis_bfd.c       | 47 ++++++++++++++++++++++++++++++++++++++++++
 isisd/isis_circuit.c   |  6 ++++++
 isisd/isis_circuit.h   |  3 +++
 4 files changed, 57 insertions(+)

diff --git a/isisd/isis_adjacency.h b/isisd/isis_adjacency.h
index 3c3a211a52..2780d826f5 100644
--- a/isisd/isis_adjacency.h
+++ b/isisd/isis_adjacency.h
@@ -139,5 +139,6 @@ void isis_adj_print_vty(struct isis_adjacency *adj, struct vty *vty,
 void isis_adj_build_neigh_list(struct list *adjdb, struct list *list);
 void isis_adj_build_up_list(struct list *adjdb, struct list *list);
 int isis_adj_usage2levels(enum isis_adj_usage usage);
+int isis_bfd_startup_timer(struct thread *thread);
 
 #endif /* ISIS_ADJACENCY_H */
diff --git a/isisd/isis_bfd.c b/isisd/isis_bfd.c
index f81dd6cf51..e74af4da21 100644
--- a/isisd/isis_bfd.c
+++ b/isisd/isis_bfd.c
@@ -329,6 +329,13 @@ static void bfd_handle_adj_up(struct isis_adjacency *adj, int command)
 	if (!circuit->bfd_info)
 		goto out;
 
+	/* If IS-IS IPv6 is configured wait for IPv6 address to be programmed
+	 * before starting up BFD
+	 */
+	if ((circuit->ipv6_router && listcount(circuit->ipv6_link) == 0)
+	    || adj->ipv6_address_count == 0)
+		return;
+
 	/*
 	 * If IS-IS is enabled for both IPv4 and IPv6 on the circuit, prefer
 	 * creating a BFD session over IPv6.
@@ -443,6 +450,44 @@ static int bfd_circuit_write_settings(struct isis_circuit *circuit,
 }
 #endif
 
+static int bfd_handle_adj_ip_enabled(struct isis_adjacency *adj, int family)
+{
+
+	if (family != AF_INET6)
+		return 0;
+
+	if (adj->bfd_session)
+		return 0;
+
+	if (adj->adj_state != ISIS_ADJ_UP)
+		return 0;
+
+	bfd_handle_adj_up(adj, ZEBRA_BFD_DEST_REGISTER);
+
+	return 0;
+}
+
+static int bfd_handle_circuit_add_addr(struct isis_circuit *circuit)
+{
+	struct isis_adjacency *adj;
+	struct listnode *node;
+
+	if (circuit->area == 0)
+		return 0;
+
+	for (ALL_LIST_ELEMENTS_RO(circuit->area->adjacency_list, node, adj)) {
+		if (adj->bfd_session)
+			continue;
+
+		if (adj->adj_state != ISIS_ADJ_UP)
+			continue;
+
+		bfd_handle_adj_up(adj, ZEBRA_BFD_DEST_REGISTER);
+	}
+
+	return 0;
+}
+
 void isis_bfd_init(void)
 {
 	bfd_gbl_init();
@@ -457,4 +502,6 @@ void isis_bfd_init(void)
 	hook_register(isis_circuit_config_write,
 		      bfd_circuit_write_settings);
 #endif
+	hook_register(isis_adj_ip_enabled_hook, bfd_handle_adj_ip_enabled);
+	hook_register(isis_circuit_add_addr_hook, bfd_handle_circuit_add_addr);
 }
diff --git a/isisd/isis_circuit.c b/isisd/isis_circuit.c
index e3c70264f8..72c17a4c70 100644
--- a/isisd/isis_circuit.c
+++ b/isisd/isis_circuit.c
@@ -248,6 +248,9 @@ struct isis_circuit *circuit_scan_by_ifp(struct interface *ifp)
 	return circuit_lookup_by_ifp(ifp, isis->init_circ_list);
 }
 
+DEFINE_HOOK(isis_circuit_add_addr_hook, (struct isis_circuit *circuit),
+	    (circuit))
+
 void isis_circuit_add_addr(struct isis_circuit *circuit,
 			   struct connected *connected)
 {
@@ -318,6 +321,9 @@ void isis_circuit_add_addr(struct isis_circuit *circuit,
 			   connected->address, circuit->interface->name);
 #endif /* EXTREME_DEBUG */
 	}
+
+	hook_call(isis_circuit_add_addr_hook, circuit);
+
 	return;
 }
 
diff --git a/isisd/isis_circuit.h b/isisd/isis_circuit.h
index b4b03bf6b9..abb09f84ef 100644
--- a/isisd/isis_circuit.h
+++ b/isisd/isis_circuit.h
@@ -221,4 +221,7 @@ DECLARE_HOOK(isis_circuit_config_write,
 	    (circuit, vty))
 #endif
 
+DECLARE_HOOK(isis_circuit_add_addr_hook, (struct isis_circuit *circuit),
+	     (circuit))
+
 #endif /* _ZEBRA_ISIS_CIRCUIT_H */
-- 
2.39.5