net: Close all connections when interface goes down

subsys/net/ip/net_context.c

@@ -650,7 +650,7 @@ int net_context_get(sa_family_t family, enum net_sock_type type, uint16_t proto,
  !net_if_is_ip_offloaded(net_if_get_default()) &&
  proto == IPPROTO_TCP) {
 /* Free the TCP context that we allocated earlier */
-net_tcp_put(&contexts[i]);
+net_tcp_put(&contexts[i], false);
 }
 
 return ret;
@@ -735,7 +735,7 @@ int net_context_put(struct net_context *context)
 context->send_cb = NULL;
 
 /* net_tcp_put() will handle decrementing refcount on stack's behalf */
-net_tcp_put(context);
+net_tcp_put(context, false);
 
 /* Decrement refcount on user app's behalf */
 net_context_unref(context);

subsys/net/ip/net_if.c

@@ -36,6 +36,7 @@ LOG_MODULE_REGISTER(net_if, CONFIG_NET_IF_LOG_LEVEL);
 #include "net_private.h"
 #include "ipv4.h"
 #include "ipv6.h"
+#include "tcp_internal.h"
 
 #include "net_stats.h"
 
@@ -5761,6 +5762,7 @@ static void notify_iface_up(struct net_if *iface)
 
 static void notify_iface_down(struct net_if *iface)
 {
+net_tcp_close_all_for_iface(iface);
 net_if_flag_clear(iface, NET_IF_RUNNING);
 net_mgmt_event_notify(NET_EVENT_IF_DOWN, iface);
 net_virtual_disable(iface);

subsys/net/ip/tcp.c

@@ -3137,7 +3137,7 @@ static enum net_verdict tcp_in(struct tcp *conn, struct net_pkt *pkt)
  * the TCP context and put the connection into
  * active close (TCP_FIN_WAIT_1).
  */
-net_tcp_put(conn->context);
+net_tcp_put(conn->context, false);
 break;
 }
 
@@ -3690,7 +3690,7 @@ static enum net_verdict tcp_in(struct tcp *conn, struct net_pkt *pkt)
 }
 
 /* Active connection close: send FIN and go to FIN_WAIT_1 state */
-int net_tcp_put(struct net_context *context)
+int net_tcp_put(struct net_context *context, bool force_close)
 {
 struct tcp *conn = context->tcp;
 
@@ -3713,26 +3713,43 @@ int net_tcp_put(struct net_context *context)
 conn->send_data_total);
 conn->in_close = true;
 
-/* How long to wait until all the data has been sent?
- */
-k_work_reschedule_for_queue(&tcp_work_q,
- &conn->send_data_timer,
- K_MSEC(TCP_RTO_MS));
+if (force_close) {
+k_work_cancel_delayable(&conn->send_data_timer);
+
+keep_alive_timer_stop(conn);
+tcp_conn_close(conn, -ENETRESET);
+} else {
+/* How long to wait until all the data has been sent?
+ */
+k_work_reschedule_for_queue(&tcp_work_q,
+ &conn->send_data_timer,
+ K_MSEC(TCP_RTO_MS));
+}
+
 } else {
-NET_DBG("[%p] TCP connection in %s close, "
-"not disposing yet (waiting %dms)",
-conn, "active", tcp_max_timeout_ms);
-k_work_reschedule_for_queue(&tcp_work_q,
- &conn->fin_timer,
- FIN_TIMEOUT);
+if (force_close) {
+NET_DBG("[%p] TCP connection in %s close, "
+"disposing immediately",
+conn, "forced");
 
-tcp_out(conn, FIN | ACK);
-conn_seq(conn, + 1);
-tcp_setup_retransmission(conn);
+keep_alive_timer_stop(conn);
+tcp_conn_close(conn, -ENETRESET);
+} else {
+NET_DBG("[%p] TCP connection in %s close, "
+"not disposing yet (waiting %dms)",
+conn, "active", tcp_max_timeout_ms);
+k_work_reschedule_for_queue(&tcp_work_q,
+ &conn->fin_timer,
+ FIN_TIMEOUT);
+
+tcp_out(conn, FIN | ACK);
+conn_seq(conn, + 1);
+tcp_setup_retransmission(conn);
 
-conn_state(conn, TCP_FIN_WAIT_1);
+conn_state(conn, TCP_FIN_WAIT_1);
 
-keep_alive_timer_stop(conn);
+keep_alive_timer_stop(conn);
+}
 }
 } else if (conn->in_connect) {
 conn->in_connect = false;
@@ -4411,7 +4428,7 @@ enum net_verdict tp_input(struct net_conn *net_conn,
 if (is("CLOSE2", tp->op)) {
 struct tcp *conn =
 (void *)sys_slist_peek_head(&tcp_conns);
-net_tcp_put(conn->context);
+net_tcp_put(conn->context, false);
 }
 if (is("RECV", tp->op)) {
 #define HEXSTR_SIZE 64
@@ -4734,6 +4751,28 @@ struct k_sem *net_tcp_conn_sem_get(struct net_context *context)
 return &conn->connect_sem;
 }
 
+static void close_tcp_conn(struct tcp *conn, void *user_data)
+{
+struct net_if *iface = user_data;
+struct net_context *context = conn->context;
+
+if (!net_context_is_used(context)) {
+return;
+}
+
+if (net_context_get_iface(context) != iface) {
+return;
+}
+
+/* net_tcp_put() will handle decrementing refcount on stack's behalf */
+net_tcp_put(context, true);
+}
+
+void net_tcp_close_all_for_iface(struct net_if *iface)
+{
+net_tcp_foreach(close_tcp_conn, iface);
+}
+
 void net_tcp_init(void)
 {
 int i;

subsys/net/ip/tcp_internal.h

@@ -354,15 +354,19 @@ static inline int net_tcp_update_recv_wnd(struct net_context *context,
  * @brief Close and delete the TCP connection for the net_context
  *
  * @param context Network context
+ * @param force_close If true, close the connection immediately. This is
+ * used e.g., when network interface goes down and we cannot wait for proper
+ * connection close procedure as we cannot send any packets anymore.
  *
  * @return 0 on success, < 0 on error
  */
 #if defined(CONFIG_NET_NATIVE_TCP)
-int net_tcp_put(struct net_context *context);
+int net_tcp_put(struct net_context *context, bool force_close);
 #else
-static inline int net_tcp_put(struct net_context *context)
+static inline int net_tcp_put(struct net_context *context, bool force_close)
 {
 ARG_UNUSED(context);
+ARG_UNUSED(force_close);
 
 return -EPROTONOSUPPORT;
 }
@@ -490,6 +494,24 @@ static inline void net_tcp_conn_accepted(struct net_context *child_ctx)
 }
 #endif
 
+/**
+ * @brief Close and unref all TCP context bound to an network interface.
+ *
+ * @details This releases all the TCP contexts that are bound to a specific
+ * network interface. It is not possible to send or receive data via those
+ * contexts after this call.
+ *
+ * @param iface The network interface to use to find out the bound contexts.
+ */
+#if defined(CONFIG_NET_NATIVE_TCP)
+void net_tcp_close_all_for_iface(struct net_if *iface);
+#else
+static inline void net_tcp_close_all_for_iface(struct net_if *iface)
+{
+ARG_UNUSED(iface);
+}
+#endif
+
 #ifdef __cplusplus
 }
 #endif