From 991bb422d417d24b25c40dbca5b312c385a5a668 Mon Sep 17 00:00:00 2001
From: Keith Whyte <keith@rhizomatica.org>
Date: Thu, 8 Aug 2019 15:43:40 +0200
Subject: [PATCH] Implement a global switch on the network to disable call
 waiting.

Add a network -> callwaiting VTY command as boolean.

When this is enabled (default) there is no change to
operation previous to this commit.

When this switch is disabled with "no call-waiting" in vty
then when a call arrives, we will check if we have an active
call transaction for this subscriber, no matter if it is
establishing, established, or alerting, in any of these cases we
will return USER BUSY to the calling party.

Change-Id: I3eb6f23f7103e3002874fb5d3a30c9de952202ae
---
 include/osmocom/msc/gsm_data.h |  3 +++
 src/libmsc/gsm_04_08_cc.c      | 22 +++++++++++++++++++---
 src/libmsc/msc_vty.c           | 28 ++++++++++++++++++++++++++++
 src/osmo-msc/msc_main.c        |  1 +
 tests/test_nodes.vty           |  2 ++
 5 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/include/osmocom/msc/gsm_data.h b/include/osmocom/msc/gsm_data.h
index a90b732af..11b6e8237 100644
--- a/include/osmocom/msc/gsm_data.h
+++ b/include/osmocom/msc/gsm_data.h
@@ -258,6 +258,9 @@ struct gsm_network {
 
 	/* Whether we want to use Osmux against BSCs. Controlled via VTY */
 	enum osmux_usage use_osmux;
+
+	/* Whether to use call waiting on the network */
+	bool call_waiting;
 };
 
 struct osmo_esme;
diff --git a/src/libmsc/gsm_04_08_cc.c b/src/libmsc/gsm_04_08_cc.c
index e83caa22f..ed74e88bb 100644
--- a/src/libmsc/gsm_04_08_cc.c
+++ b/src/libmsc/gsm_04_08_cc.c
@@ -1909,6 +1909,25 @@ static int mncc_tx_to_gsm_cc(struct gsm_network *net, const union mncc_msg *msg)
 						GSM48_CAUSE_LOC_PRN_S_LU,
 						GSM48_CC_CAUSE_DEST_OOO);
 		}
+
+		/* Find valid conn */
+		msc_a = msc_a_for_vsub(vsub, true);
+
+		/* If subscriber is BUSY and we do not DO call in call aka "call-waiting" */
+		if (!net->call_waiting && msc_a) {
+			struct gsm_trans *existing_cc_trans = trans_find_by_type(msc_a, TRANS_CC);
+			if (existing_cc_trans && existing_cc_trans->cc.state != GSM_CSTATE_NULL) {
+				LOG_TRANS_CAT(existing_cc_trans, DCC, LOGL_NOTICE,
+					      "rx '%s' for subscriber %s with trans state (%s)"
+					      " rejecting with USER_BUSY\n",
+					get_mncc_name(msg->msg_type), data->called.number,
+					gsm48_cc_state_name(existing_cc_trans->cc.state));
+				return mncc_release_ind(net, NULL, data->callref,
+							GSM48_CAUSE_LOC_PRN_S_LU,
+							GSM48_CC_CAUSE_USER_BUSY);
+			}
+		}
+
 		/* Create transaction */
 		trans = trans_alloc(net, vsub, TRANS_CC,
 				    TRANS_ID_UNASSIGNED, data->callref);
@@ -1922,9 +1941,6 @@ static int mncc_tx_to_gsm_cc(struct gsm_network *net, const union mncc_msg *msg)
 			return -ENOMEM;
 		}
 
-		/* Find valid conn */
-		msc_a = msc_a_for_vsub(vsub, true);
-
 		/* If subscriber has no conn */
 		if (!msc_a) {
 
diff --git a/src/libmsc/msc_vty.c b/src/libmsc/msc_vty.c
index 4674e2e68..09aef9168 100644
--- a/src/libmsc/msc_vty.c
+++ b/src/libmsc/msc_vty.c
@@ -330,6 +330,29 @@ DEFUN(cfg_net_no_per_loc_upd, cfg_net_no_per_loc_upd_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_net_call_wait, cfg_net_call_wait_cmd,
+      "call-waiting",
+      "Enable Call Waiting on the Network\n")
+{
+	struct gsm_network *net = vty->index;
+
+	net->call_waiting = true;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_net_no_call_wait, cfg_net_no_call_wait_cmd,
+      "no call-waiting",
+      NO_STR
+      "Disable Call Waiting on the Network\n")
+{
+	struct gsm_network *net = vty->index;
+
+	net->call_waiting = false;
+
+	return CMD_SUCCESS;
+}
+
 static int config_write_net(struct vty *vty)
 {
 	int i;
@@ -376,6 +399,9 @@ static int config_write_net(struct vty *vty)
 			gsmnet->emergency.route_to_msisdn, VTY_NEWLINE);
 	}
 
+	if (!gsmnet->call_waiting)
+		vty_out(vty, " no call-waiting%s", VTY_NEWLINE);
+
 	return CMD_SUCCESS;
 }
 
@@ -1946,6 +1972,8 @@ void msc_vty_init(struct gsm_network *msc_network)
 	install_element(GSMNET_NODE, &cfg_net_no_timezone_cmd);
 	install_element(GSMNET_NODE, &cfg_net_per_loc_upd_cmd);
 	install_element(GSMNET_NODE, &cfg_net_no_per_loc_upd_cmd);
+	install_element(GSMNET_NODE, &cfg_net_call_wait_cmd);
+	install_element(GSMNET_NODE, &cfg_net_no_call_wait_cmd);
 
 	install_element(CONFIG_NODE, &cfg_msc_cmd);
 	install_node(&msc_node, config_write_msc);
diff --git a/src/osmo-msc/msc_main.c b/src/osmo-msc/msc_main.c
index 1083271a9..3860589e7 100644
--- a/src/osmo-msc/msc_main.c
+++ b/src/osmo-msc/msc_main.c
@@ -216,6 +216,7 @@ struct gsm_network *msc_network_alloc(void *ctx,
 
 	mgcp_client_conf_init(&net->mgw.conf);
 	net->mgw.tdefs = g_mgw_tdefs;
+	net->call_waiting = true;
 
 	return net;
 }
diff --git a/tests/test_nodes.vty b/tests/test_nodes.vty
index 0ad390fc5..a4e0e15db 100644
--- a/tests/test_nodes.vty
+++ b/tests/test_nodes.vty
@@ -26,6 +26,8 @@ OsmoMSC(config-net)# list
   no timezone
   periodic location update <6-1530>
   no periodic location update
+  call-waiting
+  no call-waiting
 
 OsmoMSC(config-net)# encryption?
   encryption  Encryption options