osmo-bsc_nat: Have a default MSC for messages from BSC

Change-Id: I343e6d9d17bcde6dbdf8f48b7b51e998a296680c
Ticket: SYS#3208
Sponsored-by: On-Waves ehf.

4 files changed, 28 insertions, 3 deletions

diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index 32be4d9dd..f6c1aaa9f 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -275,6 +275,7 @@ struct bsc_nat {
 	/* MSC connections */
 	struct llist_head msc_configs;
 	int num_msc;
+	int default_msc;
 
 	/* timeouts */
 	int auth_timeout;
@@ -350,6 +351,7 @@ int bsc_config_handles_lac(struct bsc_config *cfg, int lac);
 struct msc_config *msc_config_alloc(struct bsc_nat *nat);
 struct msc_config *msc_config_num(struct bsc_nat *nat, int num);
 struct msc_config *msc_config_by_con(struct bsc_nat *nat, struct bsc_msc_connection *msc_con);
+struct bsc_msc_connection *msc_conn_by_num(struct bsc_nat *nat, int num);
 struct bsc_msc_connection *msc_conn_by_imsi(struct bsc_nat *nat, const char *imsi);
 void msc_config_free(struct msc_config *);
 
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index da923a45d..7936e0dab 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -1154,11 +1154,13 @@ static int forward_sccp_to_msc(struct bsc_connection *bsc, struct msgb *msg)
 				goto exit2;
 			con = patch_sccp_src_ref_to_msc(msg, parsed, bsc);
 
-#warning Implement routing by IMSI
-			if (!imsi)
-				LOGP(DNAT, LOGL_ERROR, "No IMSI for CR\n");
 
 			con->msc_con = msc_conn_by_imsi(bsc->nat, imsi);
+			if (!con->msc_con) {
+				/* Fall back to default MSC */
+				LOGP(DNAT, LOGL_NOTICE, "Falling back to default MSC\n");
+				con->msc_con = msc_conn_by_num(bsc->nat, bsc->nat->default_msc);
+			}
 			con_msc = con->msc_con;
 			con->filter_state.con_type = con_type;
 			con->filter_state.imsi_checked = filter;
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
index 57c62a4f3..bed5af66c 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_utils.c
@@ -250,6 +250,18 @@ struct msc_config *msc_config_by_con(struct bsc_nat *nat, struct bsc_msc_connect
 	return NULL;
 }
 
+struct bsc_msc_connection *msc_conn_by_num(struct bsc_nat *nat, int num)
+{
+	struct msc_config *conf;
+
+	conf = msc_config_num(nat, num);
+
+	if (!conf)
+		return NULL;
+
+	return conf->msc_con;
+}
+
 struct bsc_msc_connection *msc_conn_by_imsi(struct bsc_nat *nat, const char *imsi)
 {
 	struct msc_config *conf;
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c b/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
index 4c42791b5..5d37b521e 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
@@ -758,6 +758,14 @@ DEFUN(cfg_nat_use_ipa_for_mgcp,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_nat_default_msc,
+      cfg_nat_default_msc_cmd,
+      "default msc NR",
+      "The MSC to route messages to by default\n" "MSC number\n")
+{
+	_nat->default_msc = atoi(argv[0]);
+}
+
 DEFUN(cfg_nat_sdp_amr_mode_set,
       cfg_nat_sdp_amr_mode_set_cmd,
       "sdp-ensure-amr-mode-set",
@@ -1279,6 +1287,7 @@ int bsc_nat_vty_init(struct bsc_nat *nat)
 	install_element(NAT_NODE, &cfg_nat_ussd_token_cmd);
 	install_element(NAT_NODE, &cfg_nat_ussd_local_cmd);
 	install_element(NAT_NODE, &cfg_nat_use_ipa_for_mgcp_cmd);
+	install_element(NAT_NODE, &cfg_nat_default_msc_cmd);
 
 	bsc_msg_lst_vty_init(nat, &nat->access_lists, NAT_NODE);