reconnect loop on dropped connection

final/src/mqtt/client.rs

@@ -5,62 +5,66 @@ use log::info;
 use rust_mqtt::client::client::MqttClient;
 use rust_mqtt::client::client_config::{ClientConfig, MqttVersion};
 use rust_mqtt::packet::v5::publish_packet::QualityOfService;
+use rust_mqtt::packet::v5::reason_codes::ReasonCode;
 use rust_mqtt::utils::rng_generator::CountingRng;
 use static_cell::ConstStaticCell;
 
 use crate::mqtt::config::mqtt_broker_endpoint;
 
+const RECONNECT_DELAY_SECS: u64 = 5;
+
 // TCP socket buffers (for embassy-net TcpSocket)
 static TCP_RX_BUFFER: ConstStaticCell<[u8; 2048]> = ConstStaticCell::new([0; 2048]);
 static TCP_TX_BUFFER: ConstStaticCell<[u8; 2048]> = ConstStaticCell::new([0; 2048]);
 
-// MQTT client buffers (separate from the TcpSocket’s buffers)
+// MQTT client buffers (separate from the TcpSocket's buffers)
 static MQTT_TX_BUF: ConstStaticCell<[u8; 1024]> = ConstStaticCell::new([0; 1024]);
 static MQTT_RX_BUF: ConstStaticCell<[u8; 1024]> = ConstStaticCell::new([0; 1024]);
 
-#[embassy_executor::task]
-pub async fn mqtt_task(stack: Stack<'static>) {
-    info!("MQTT task starting...");
+// Type alias for clarity in helper functions
+// NOTE: Tie the TcpSocket lifetime to the session (not 'static), and
+// the MQTT buffers lifetime to 'a. This resolves the E0521 error.
+// The const 8 is the MAX_PROPERTIES generic used by rust-mqtt config.
+type Client<'a, 'net> = MqttClient<'a, TcpSocket<'net>, 8, CountingRng>;
 
-    let tcp_rx = TCP_RX_BUFFER.take();
-    let tcp_tx = TCP_TX_BUFFER.take();
-    let mut socket = TcpSocket::new(stack, tcp_rx, tcp_tx);
-
-    match socket.connect(mqtt_broker_endpoint()).await {
-        Ok(_) => info!("Connected TCP to MQTT broker"),
-        Err(e) => {
-            info!("TCP connect failed: {:?}", e);
-            return;
-        }
-    }
-
-    let mqtt_tx = MQTT_TX_BUF.take();
-    let mqtt_rx = MQTT_RX_BUF.take();
-
-    // Config
+fn build_client_config() -> ClientConfig<'static, 8, CountingRng> {
     let rng = CountingRng(0);
     let mut cfg: ClientConfig<'static, 8, _> = ClientConfig::new(MqttVersion::MQTTv5, rng);
     cfg.keep_alive = 60;
     cfg.add_client_id("esp32-client");
-    // cfg.add_username("user");
-    // cfg.add_password("pass");
+    cfg
+}
 
+fn build_client<'a, 'net>(
+    socket: TcpSocket<'net>,
+    mqtt_tx: &'a mut [u8],
+    mqtt_rx: &'a mut [u8],
+) -> Client<'a, 'net> {
+    let cfg = build_client_config();
     let mqtt_tx_len = mqtt_tx.len();
     let mqtt_rx_len = mqtt_rx.len();
+    MqttClient::new(socket, mqtt_tx, mqtt_tx_len, mqtt_rx, mqtt_rx_len, cfg)
+}
 
-    let mut client = MqttClient::new(socket, mqtt_tx, mqtt_tx_len, mqtt_rx, mqtt_rx_len, cfg);    
-
-    // Connect
-    match client.connect_to_broker().await {
-        Ok(_) => info!("MQTT CONNACK received"),
-        Err(reason) => {
-            info!("MQTT connect failed: {:?}", reason);
-            return;
+async fn connect_tcp<'net>(socket: &mut TcpSocket<'net>) -> Result<(), ()> {
+    match socket.connect(mqtt_broker_endpoint()).await {
+        Ok(_) => {
+            info!("Connected TCP to MQTT broker");
+            Ok(())
+        }
+        Err(e) => {
+            info!("TCP connect failed: {:?}", e);
+            Err(())
         }
     }
+}
 
-    // Publish simple message
-    match client
+async fn connect_mqtt(client: &mut Client<'_, '_>) -> Result<(), ReasonCode> {
+    client.connect_to_broker().await
+}
+
+async fn publish_once(client: &mut Client<'_, '_>) -> Result<(), ReasonCode> {
+    client
         .send_message(
             "esp32/topic",
             b"hello from esp32",
@@ -68,16 +72,76 @@ pub async fn mqtt_task(stack: Stack<'static>) {
             false,
         )
         .await
-    {
-        Ok(_) => info!("MQTT PUBLISH sent"),
-        Err(reason) => info!("MQTT publish failed: {:?}", reason),
-    }
+}
 
+async fn ping_loop(client: &mut Client<'_, '_>) -> Result<(), ReasonCode> {
     loop {
         if let Err(reason) = client.send_ping().await {
             info!("MQTT ping failed: {:?}", reason);
-            break;
+            return Err(reason);
         }
         Timer::after(Duration::from_secs(30)).await;
     }
 }
+
+// One full MQTT session: TCP connect -> MQTT connect -> (optional) publish -> ping loop
+async fn run_one_session(
+    stack: Stack<'static>,
+    tcp_rx: &mut [u8],
+    tcp_tx: &mut [u8],
+    mqtt_tx: &mut [u8],
+    mqtt_rx: &mut [u8],
+) -> Result<(), ()> {
+    // Build socket and connect TCP
+    let mut socket = TcpSocket::new(stack, tcp_rx, tcp_tx);
+    if connect_tcp(&mut socket).await.is_err() {
+        return Err(());
+    }
+
+    // Build client and connect MQTT
+    let mut client = build_client(socket, mqtt_tx, mqtt_rx);
+    match connect_mqtt(&mut client).await {
+        Ok(_) => info!("MQTT CONNACK received"),
+        Err(reason) => {
+            info!("MQTT connect failed: {:?}", reason);
+            return Err(());
+        }
+    }
+
+    // Optional demo publish (same behavior as before)
+    match publish_once(&mut client).await {
+        Ok(_) => info!("MQTT PUBLISH sent"),
+        Err(reason) => info!("MQTT publish failed: {:?}", reason),
+    }
+
+    // Keepalive. Any error ends the session; outer loop will reconnect.
+    ping_loop(&mut client).await.map_err(|_| ())
+}
+
+#[embassy_executor::task]
+pub async fn mqtt_task(stack: Stack<'static>) {
+    info!("MQTT task starting...");
+
+    // Take static buffers once and reuse across reconnects
+    let mut tcp_rx = TCP_RX_BUFFER.take();
+    let mut tcp_tx = TCP_TX_BUFFER.take();
+    let mut mqtt_tx = MQTT_TX_BUF.take();
+    let mut mqtt_rx = MQTT_RX_BUF.take();
+
+    loop {
+        let _ = run_one_session(
+            stack,
+            &mut tcp_rx[..],
+            &mut tcp_tx[..],
+            &mut mqtt_tx[..],
+            &mut mqtt_rx[..],
+        )
+        .await;
+
+        info!(
+            "Reconnecting in {}s after session end/failure",
+            RECONNECT_DELAY_SECS
+        );
+        Timer::after(Duration::from_secs(RECONNECT_DELAY_SECS)).await;
+    }
+}