Remove inappropriate warning on MQTT connect

Since #3823,
an inappropriate warning is printed
when a non-TLS connection is established to the local broker:

$ tedge mqtt sub te/#
2025-11-18T14:47:04.179834205Z  WARN MQTT: Connecting on port 1883 for insecure MQTT using a TLS connection

This warning is inappropriate because the connection is *not* established over TLS:
neither a client certificate nor root certificates have been configured.

Signed-off-by: Didier Wenzek <[email protected]>

Author: didier-wenzek

crates/common/mqtt_channel/src/config.rs

@@ -80,6 +80,14 @@ pub struct BrokerConfig {
     pub authentication: Option<AuthenticationConfig>,
 }
 
+impl BrokerConfig {
+    pub fn is_using_tls(&self) -> bool {
+        self.authentication
+            .as_ref()
+            .is_some_and(|a| a.is_using_tls())
+    }
+}
+
 /// MQTT certificate authentication configuration.
 ///
 /// Intended to mirror authentication model found in the [mosquitto] MQTT
@@ -143,6 +151,10 @@ impl AuthenticationConfig {
         self.password = Some(password);
     }
 
+    pub fn is_using_tls(&self) -> bool {
+        !self.cert_store.is_empty()
+    }
+
     pub fn to_rustls_client_config(&self) -> Result<Option<rustls::ClientConfig>, rustls::Error> {
         if self.cert_store.is_empty() {
             return Ok(None);

crates/common/mqtt_channel/src/connection.rs

@@ -219,10 +219,10 @@ impl Connection {
         const INSECURE_MQTT_PORT: u16 = 1883;
         const SECURE_MQTT_PORT: u16 = 8883;
 
-        if config.broker.port == INSECURE_MQTT_PORT && config.broker.authentication.is_some() {
+        if config.broker.port == INSECURE_MQTT_PORT && config.broker.is_using_tls() {
             warn!(target: "MQTT", "Connecting on port 1883 for insecure MQTT using a TLS connection");
         }
-        if config.broker.port == SECURE_MQTT_PORT && config.broker.authentication.is_none() {
+        if config.broker.port == SECURE_MQTT_PORT && !config.broker.is_using_tls() {
             warn!(target: "MQTT", "Connecting on port 8883 for secure MQTT without a CA file");
         }