vty: Add VTY command about the state of the mncc connection

Add VTY command with the state of the MNCC connection. It gives
a simple state and is connected in case of the READY state.

src/mncc.c

@@ -805,3 +805,10 @@ void mncc_connection_start(struct mncc_connection *conn)
 	LOGP(DMNCC, LOGL_NOTICE, "Scheduling MNCC connect\n");
 	osmo_timer_schedule(&conn->reconnect, 0, 0);
 }
+
+const struct value_string mncc_conn_state_vals[] = {
+	{ MNCC_DISCONNECTED,	"DISCONNECTED"	},
+	{ MNCC_WAIT_VERSION,	"WAITING"	},
+	{ MNCC_READY,		"READY"		},
+	{ 0, NULL },
+};

src/mncc.h

@@ -2,6 +2,7 @@
 
 #include <osmocom/core/select.h>
 #include <osmocom/core/timer.h>
+#include <osmocom/core/utils.h>
 
 #include <stdint.h>
 
@@ -31,3 +32,5 @@ void mncc_connection_init(struct mncc_connection *conn, struct app_config *cfg);
 void mncc_connection_start(struct mncc_connection *conn);
 
 int mncc_create_remote_leg(struct mncc_connection *conn, struct call *call);
+
+extern const struct value_string mncc_conn_state_vals[];

src/vty.c

@@ -21,6 +21,7 @@
 #include "vty.h"
 #include "app.h"
 #include "call.h"
+#include "mncc.h"
 
 #include <talloc.h>
 
@@ -274,6 +275,17 @@ DEFUN(show_calls_sum, show_calls_sum_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(show_mncc_conn, show_mncc_conn_cmd,
+	"show mncc-connection",
+	SHOW_STR "MNCC Connection state\n")
+{
+	vty_out(vty, "MNCC connection to path '%s' is in state %s%s",
+		g_app.mncc.path,
+		get_value_string(mncc_conn_state_vals, g_app.mncc.conn.state),
+		VTY_NEWLINE);
+	return CMD_SUCCESS;
+}
+
 void mncc_sip_vty_init(void)
 {
 	/* default values */
@@ -302,4 +314,5 @@ void mncc_sip_vty_init(void)
 
 	install_element_ve(&show_calls_cmd);
 	install_element_ve(&show_calls_sum_cmd);
+	install_element_ve(&show_mncc_conn_cmd);
 }