net: lwm2m: Add transmission state indicator to RX as well

Refactored the socket state indication into its own function
that checks the state of TX queues as well as number of
pending CoAP responses.
Check the state after receiving a packet, as it might
have been a last Ack packet we have been waiting.

Signed-off-by: Seppo Takalo <[email protected]>

Author: SeppoTakalo

subsys/net/lib/lwm2m/lwm2m_engine.c

@@ -630,6 +630,50 @@ static int64_t check_notifications(struct lwm2m_ctx *ctx, const int64_t timestam
 	return next;
 }
 
+/**
+ * @brief Check TX queue states as well as number or pending CoAP transmissions.
+ *
+ * If all queues are empty and there is no packet we are currently transmitting and no
+ * CoAP responses (pendings) we are waiting, inform the application by a callback
+ * that socket is in state LWM2M_SOCKET_STATE_NO_DATA.
+ * Otherwise, before sending a packet, depending on the state of the queues, inform with
+ * one of the ONGOING, ONE_RESPONSE or LAST indicators.
+ *
+ * @param ctx Client context.
+ * @param ongoing_tx Current packet to be transmitted or NULL.
+ */
+static void hint_socket_state(struct lwm2m_ctx *ctx, struct lwm2m_message *ongoing_tx)
+{
+	if (!ctx->set_socket_state) {
+		return;
+	}
+
+#if defined(CONFIG_LWM2M_QUEUE_MODE_ENABLED)
+	bool empty = sys_slist_is_empty(&ctx->pending_sends) &&
+		     sys_slist_is_empty(&ctx->queued_messages);
+#else
+	bool empty = sys_slist_is_empty(&ctx->pending_sends);
+#endif
+	size_t pendings = coap_pendings_count(ctx->pendings, ARRAY_SIZE(ctx->pendings));
+
+	if (ongoing_tx) {
+		/* Check if more than current TX is in pendings list*/
+		if (pendings > 1) {
+			empty = false;
+		}
+
+		if (!empty) {
+			ctx->set_socket_state(ctx->sock_fd, LWM2M_SOCKET_STATE_ONGOING);
+		} else if (ongoing_tx->type == COAP_TYPE_CON) {
+			ctx->set_socket_state(ctx->sock_fd, LWM2M_SOCKET_STATE_ONE_RESPONSE);
+		} else {
+			ctx->set_socket_state(ctx->sock_fd, LWM2M_SOCKET_STATE_LAST);
+		}
+	} else if (empty && pendings == 0) {
+		ctx->set_socket_state(ctx->sock_fd, LWM2M_SOCKET_STATE_NO_DATA);
+	}
+}
+
 static int socket_recv_message(struct lwm2m_ctx *client_ctx)
 {
 	static uint8_t in_buf[NET_IPV6_MTU];
@@ -684,31 +728,7 @@ static int socket_send_message(struct lwm2m_ctx *ctx)
 		coap_pending_cycle(msg->pending);
 	}
 
-	if (ctx->set_socket_state) {
-#if defined(CONFIG_LWM2M_QUEUE_MODE_ENABLED)
-		bool empty = sys_slist_is_empty(&ctx->pending_sends) &&
-			     sys_slist_is_empty(&ctx->queued_messages);
-#else
-		bool empty = sys_slist_is_empty(&ctx->pending_sends);
-#endif
-		if (coap_pendings_count(ctx->pendings, ARRAY_SIZE(ctx->pendings)) > 1) {
-			empty = false;
-		}
-
-		if (!empty) {
-			ctx->set_socket_state(ctx->sock_fd, LWM2M_SOCKET_STATE_ONGOING);
-		} else {
-			switch (msg->type) {
-			case COAP_TYPE_CON:
-				ctx->set_socket_state(ctx->sock_fd,
-						      LWM2M_SOCKET_STATE_ONE_RESPONSE);
-				break;
-			default:
-				ctx->set_socket_state(ctx->sock_fd, LWM2M_SOCKET_STATE_LAST);
-				break;
-			}
-		}
-	}
+	hint_socket_state(ctx, msg);
 
 	rc = zsock_send(msg->ctx->sock_fd, msg->cpkt.data, msg->cpkt.offset, 0);
 
@@ -847,6 +867,8 @@ static void socket_loop(void *p1, void *p2, void *p3)
 						break;
 					}
 				}
+
+				hint_socket_state(sock_ctx[i], NULL);
 			}
 
 			if (sock_fds[i].revents & ZSOCK_POLLOUT) {