From ba1c49028fa9cef24c3f4fef91e5d3123affd24b Mon Sep 17 00:00:00 2001
From: Oliver Smith <osmith@sysmocom.de>
Date: Thu, 24 Mar 2022 13:00:36 +0100
Subject: [PATCH] Proper exit if bsc_nat_fsm fails to start

Instead of segfaulting later on, properly exit if the bsc_nat_fsm does
not start. One reason for having it fail could be a missing mgw pool
config block.

Related: SYS#5560
Change-Id: Ia8bbe6ae908d5c3ce49f71b43c950497aeebb6d6
---
 include/osmocom/bsc_nat/bsc_nat_fsm.h |  2 +-
 src/osmo-bsc-nat/bsc_nat_fsm.c        | 13 +++++++++++--
 src/osmo-bsc-nat/main.c               |  3 ++-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/osmocom/bsc_nat/bsc_nat_fsm.h b/include/osmocom/bsc_nat/bsc_nat_fsm.h
index a2becfb..bca97e1 100644
--- a/include/osmocom/bsc_nat/bsc_nat_fsm.h
+++ b/include/osmocom/bsc_nat/bsc_nat_fsm.h
@@ -20,5 +20,5 @@
 #pragma once
 
 void bsc_nat_fsm_alloc(struct bsc_nat *bsc_nat);
-void bsc_nat_fsm_start(struct bsc_nat *bsc_nat);
+int bsc_nat_fsm_start(struct bsc_nat *bsc_nat);
 void bsc_nat_fsm_stop(struct bsc_nat *bsc_nat);
diff --git a/src/osmo-bsc-nat/bsc_nat_fsm.c b/src/osmo-bsc-nat/bsc_nat_fsm.c
index 30486ce..eae2f5e 100644
--- a/src/osmo-bsc-nat/bsc_nat_fsm.c
+++ b/src/osmo-bsc-nat/bsc_nat_fsm.c
@@ -474,9 +474,18 @@ void bsc_nat_fsm_alloc(struct bsc_nat *bsc_nat)
 	OSMO_ASSERT(bsc_nat->fi);
 }
 
-void bsc_nat_fsm_start(struct bsc_nat *bsc_nat)
+int bsc_nat_fsm_start(struct bsc_nat *bsc_nat)
 {
-	osmo_fsm_inst_dispatch(bsc_nat->fi, BSC_NAT_FSM_EV_START, NULL);
+	int rc = osmo_fsm_inst_dispatch(bsc_nat->fi, BSC_NAT_FSM_EV_START, NULL);
+	if (rc)
+		return rc;
+
+	/* st_starting_on_enter() doesn't change to STARTED if e.g. vty config
+	 * is incomplete */
+	if (bsc_nat->fi->state != BSC_NAT_FSM_ST_STARTED)
+		return -1;
+
+	return 0;
 }
 
 void bsc_nat_fsm_stop(struct bsc_nat *bsc_nat)
diff --git a/src/osmo-bsc-nat/main.c b/src/osmo-bsc-nat/main.c
index 6cb1e0f..e58d687 100644
--- a/src/osmo-bsc-nat/main.c
+++ b/src/osmo-bsc-nat/main.c
@@ -198,7 +198,8 @@ int main(int argc, char **argv)
 	main_vty_init(argc, argv);
 	signal_handler_init();
 
-	bsc_nat_fsm_start(g_bsc_nat);
+	if (bsc_nat_fsm_start(g_bsc_nat) < 0)
+		exit(1);
 
 	if (msc_alloc_from_addr_book() < 0)
 		exit(1);