[nrf fromtree] net: zperf: Fix session leak

In case zperf session was aborted by the user (by for instance stopping
it from shell), or practically in case of any other
communication-related error, the zperf session could end up in a state
other than NULL or COMPLETED, with no way to recover. This made the
session no longer usable and eventually could lead to zperf being not
able to start a new session anymore.

Fix this by introducing zperf_session_reset() function, which resets the
session state back to defaults. The function is called when the zperf
receiver service is stopped.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
(cherry picked from commit 68bc981)

subsys/net/lib/zperf/zperf_session.c

@@ -102,14 +102,27 @@ void zperf_reset_session_stats(struct session *session)
 	session->last_transit_time = 0;
 }
 
-void zperf_session_init(void)
+void zperf_session_reset(enum session_proto proto)
 {
 	int i, j;
 
+	if (proto >= SESSION_PROTO_END) {
+		return;
+	}
+
+	i = (int)proto;
+
+	for (j = 0; j < SESSION_MAX; j++) {
+		sessions[i][j].state = STATE_NULL;
+		zperf_reset_session_stats(&(sessions[i][j]));
+	}
+}
+
+void zperf_session_init(void)
+{
+	int i;
+
 	for (i = 0; i < SESSION_PROTO_END; i++) {
-		for (j = 0; j < SESSION_MAX; j++) {
-			sessions[i][j].state = STATE_NULL;
-			zperf_reset_session_stats(&(sessions[i][j]));
-		}
+		zperf_session_reset(i);
 	}
 }

subsys/net/lib/zperf/zperf_session.h

@@ -58,5 +58,7 @@ struct session *get_session(const struct sockaddr *addr,
 			    enum session_proto proto);
 void zperf_session_init(void);
 void zperf_reset_session_stats(struct session *session);
+/* Reset all sessions for a given protocol. */
+void zperf_session_reset(enum session_proto proto);
 
 #endif /* __ZPERF_SESSION_H */

subsys/net/lib/zperf/zperf_tcp_receiver.c

@@ -117,6 +117,8 @@ static void tcp_receiver_cleanup(void)
 
 	tcp_server_running = false;
 	tcp_session_cb = NULL;
+
+	zperf_session_reset(SESSION_TCP);
 }
 
 static int tcp_recv_data(struct net_socket_service_event *pev)

subsys/net/lib/zperf/zperf_udp_receiver.c

@@ -240,6 +240,8 @@ static void udp_receiver_cleanup(void)
 
 	udp_server_running = false;
 	udp_session_cb = NULL;
+
+	zperf_session_reset(SESSION_UDP);
 }
 
 static int udp_recv_data(struct net_socket_service_event *pev)