[wifi, captive_portal, web_server, wifi_info] Use stack allocation for MAC address formatting (#11963)

esphome/components/api/api_connection.cpp

@@ -90,8 +90,8 @@ static const int CAMERA_STOP_STREAM = 5000;
 APIConnection::APIConnection(std::unique_ptr<socket::Socket> sock, APIServer *parent)
     : parent_(parent), initial_state_iterator_(this), list_entities_iterator_(this) {
 #if defined(USE_API_PLAINTEXT) && defined(USE_API_NOISE)
-  auto &noise_ctx = parent->get_noise_ctx();
-  if (noise_ctx.has_psk()) {
+  auto noise_ctx = parent->get_noise_ctx();
+  if (noise_ctx->has_psk()) {
     this->helper_ =
         std::unique_ptr<APIFrameHelper>{new APINoiseFrameHelper(std::move(sock), noise_ctx, &this->client_info_)};
   } else {

esphome/components/api/api_frame_helper_noise.cpp

@@ -527,7 +527,7 @@ APIError APINoiseFrameHelper::init_handshake_() {
   if (aerr != APIError::OK)
     return aerr;
 
-  const auto &psk = this->ctx_.get_psk();
+  const auto &psk = ctx_->get_psk();
   err = noise_handshakestate_set_pre_shared_key(handshake_, psk.data(), psk.size());
   aerr = handle_noise_error_(err, LOG_STR("noise_handshakestate_set_pre_shared_key"),
                              APIError::HANDSHAKESTATE_SETUP_FAILED);

esphome/components/api/api_frame_helper_noise.h

@@ -9,8 +9,9 @@ namespace esphome::api {
 
 class APINoiseFrameHelper final : public APIFrameHelper {
  public:
-  APINoiseFrameHelper(std::unique_ptr<socket::Socket> socket, APINoiseContext &ctx, const ClientInfo *client_info)
-      : APIFrameHelper(std::move(socket), client_info), ctx_(ctx) {
+  APINoiseFrameHelper(std::unique_ptr<socket::Socket> socket, std::shared_ptr<APINoiseContext> ctx,
+                      const ClientInfo *client_info)
+      : APIFrameHelper(std::move(socket), client_info), ctx_(std::move(ctx)) {
     // Noise header structure:
     // Pos 0: indicator (0x01)
     // Pos 1-2: encrypted payload size (16-bit big-endian)
@@ -40,8 +41,8 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   NoiseCipherState *send_cipher_{nullptr};
   NoiseCipherState *recv_cipher_{nullptr};
 
-  // Reference to noise context (4 bytes on 32-bit)
-  APINoiseContext &ctx_;
+  // Shared pointer (8 bytes on 32-bit = 4 bytes control block pointer + 4 bytes object pointer)
+  std::shared_ptr<APINoiseContext> ctx_;
 
   // Vector (12 bytes on 32-bit)
   std::vector<uint8_t> prologue_;

esphome/components/api/api_server.cpp

@@ -227,8 +227,8 @@ void APIServer::dump_config() {
                 "  Max connections: %u",
                 network::get_use_address(), this->port_, this->listen_backlog_, this->max_connections_);
 #ifdef USE_API_NOISE
-  ESP_LOGCONFIG(TAG, "  Noise encryption: %s", YESNO(this->noise_ctx_.has_psk()));
-  if (!this->noise_ctx_.has_psk()) {
+  ESP_LOGCONFIG(TAG, "  Noise encryption: %s", YESNO(this->noise_ctx_->has_psk()));
+  if (!this->noise_ctx_->has_psk()) {
     ESP_LOGCONFIG(TAG, "  Supports encryption: YES");
   }
 #else
@@ -493,7 +493,7 @@ bool APIServer::save_noise_psk(psk_t psk, bool make_active) {
   ESP_LOGW(TAG, "Key set in YAML");
   return false;
 #else
-  auto &old_psk = this->noise_ctx_.get_psk();
+  auto &old_psk = this->noise_ctx_->get_psk();
   if (std::equal(old_psk.begin(), old_psk.end(), psk.begin())) {
     ESP_LOGW(TAG, "New PSK matches old");
     return true;

esphome/components/api/api_server.h

@@ -54,8 +54,8 @@ class APIServer : public Component, public Controller {
 #ifdef USE_API_NOISE
   bool save_noise_psk(psk_t psk, bool make_active = true);
   bool clear_noise_psk(bool make_active = true);
-  void set_noise_psk(psk_t psk) { this->noise_ctx_.set_psk(psk); }
-  APINoiseContext &get_noise_ctx() { return this->noise_ctx_; }
+  void set_noise_psk(psk_t psk) { noise_ctx_->set_psk(psk); }
+  std::shared_ptr<APINoiseContext> get_noise_ctx() { return noise_ctx_; }
 #endif  // USE_API_NOISE
 
   void handle_disconnect(APIConnection *conn);
@@ -228,7 +228,7 @@ class APIServer : public Component, public Controller {
   // 7 bytes used, 1 byte padding
 
 #ifdef USE_API_NOISE
-  APINoiseContext noise_ctx_;
+  std::shared_ptr<APINoiseContext> noise_ctx_ = std::make_shared<APINoiseContext>();
   ESPPreferenceObject noise_pref_;
 #endif  // USE_API_NOISE
 };

esphome/components/captive_portal/captive_portal.cpp

@@ -13,14 +13,16 @@ static const char *const TAG = "captive_portal";
 void CaptivePortal::handle_config(AsyncWebServerRequest *request) {
   AsyncResponseStream *stream = request->beginResponseStream(ESPHOME_F("application/json"));
   stream->addHeader(ESPHOME_F("cache-control"), ESPHOME_F("public, max-age=0, must-revalidate"));
+  char mac_s[18];
+  const char *mac_str = get_mac_address_pretty_into_buffer(mac_s);
 #ifdef USE_ESP8266
   stream->print(ESPHOME_F("{\"mac\":\""));
-  stream->print(get_mac_address_pretty().c_str());
+  stream->print(mac_str);
   stream->print(ESPHOME_F("\",\"name\":\""));
   stream->print(App.get_name().c_str());
   stream->print(ESPHOME_F("\",\"aps\":[{}"));
 #else
-  stream->printf(R"({"mac":"%s","name":"%s","aps":[{})", get_mac_address_pretty().c_str(), App.get_name().c_str());
+  stream->printf(R"({"mac":"%s","name":"%s","aps":[{})", mac_str, App.get_name().c_str());
 #endif
 
   for (auto &scan : wifi::global_wifi_component->get_scan_result()) {

esphome/components/mdns/mdns_component.cpp

@@ -119,7 +119,7 @@ void MDNSComponent::compile_records_(StaticVector<MDNSService, MDNS_SERVICE_COUN
     MDNS_STATIC_CONST_CHAR(TXT_API_ENCRYPTION, "api_encryption");
     MDNS_STATIC_CONST_CHAR(TXT_API_ENCRYPTION_SUPPORTED, "api_encryption_supported");
     MDNS_STATIC_CONST_CHAR(NOISE_ENCRYPTION, "Noise_NNpsk0_25519_ChaChaPoly_SHA256");
-    bool has_psk = api::global_api_server->get_noise_ctx().has_psk();
+    bool has_psk = api::global_api_server->get_noise_ctx()->has_psk();
     const char *encryption_key = has_psk ? TXT_API_ENCRYPTION : TXT_API_ENCRYPTION_SUPPORTED;
     txt_records.push_back({MDNS_STR(encryption_key), MDNS_STR(NOISE_ENCRYPTION)});
 #endif

esphome/components/mqtt/mqtt_client.cpp

@@ -140,7 +140,7 @@ void MQTTClientComponent::send_device_info_() {
 #endif
 
 #ifdef USE_API_NOISE
-        root[api::global_api_server->get_noise_ctx().has_psk() ? "api_encryption" : "api_encryption_supported"] =
+        root[api::global_api_server->get_noise_ctx()->has_psk() ? "api_encryption" : "api_encryption_supported"] =
             "Noise_NNpsk0_25519_ChaChaPoly_SHA256";
 #endif
       },

esphome/components/web_server/web_server.cpp

@@ -359,8 +359,8 @@ void WebServer::handle_pna_cors_request(AsyncWebServerRequest *request) {
   AsyncWebServerResponse *response = request->beginResponse(200, "");
   response->addHeader(HEADER_CORS_ALLOW_PNA, "true");
   response->addHeader(HEADER_PNA_NAME, App.get_name().c_str());
-  std::string mac = get_mac_address_pretty();
-  response->addHeader(HEADER_PNA_ID, mac.c_str());
+  char mac_s[18];
+  response->addHeader(HEADER_PNA_ID, get_mac_address_pretty_into_buffer(mac_s));
   request->send(response);
 }
 #endif

esphome/components/wifi/wifi_component.cpp

@@ -341,10 +341,11 @@ void WiFiComponent::setup() {
 }
 
 void WiFiComponent::start() {
+  char mac_s[18];
   ESP_LOGCONFIG(TAG,
                 "Starting\n"
                 "  Local MAC: %s",
-                get_mac_address_pretty().c_str());
+                get_mac_address_pretty_into_buffer(mac_s));
   this->last_connected_ = millis();
 
   uint32_t hash = this->has_sta() ? fnv1_hash(App.get_compilation_time()) : 88491487UL;
@@ -826,7 +827,8 @@ void WiFiComponent::print_connect_params_() {
   char bssid_s[18];
   format_mac_addr_upper(bssid.data(), bssid_s);
 
-  ESP_LOGCONFIG(TAG, "  Local MAC: %s", get_mac_address_pretty().c_str());
+  char mac_s[18];
+  ESP_LOGCONFIG(TAG, "  Local MAC: %s", get_mac_address_pretty_into_buffer(mac_s));
   if (this->is_disabled()) {
     ESP_LOGCONFIG(TAG, "  Disabled");
     return;

esphome/components/wifi_info/wifi_info_text_sensor.h

@@ -126,7 +126,10 @@ class BSSIDWiFiInfo : public PollingComponent, public text_sensor::TextSensor {
 
 class MacAddressWifiInfo : public Component, public text_sensor::TextSensor {
  public:
-  void setup() override { this->publish_state(get_mac_address_pretty()); }
+  void setup() override {
+    char mac_s[18];
+    this->publish_state(get_mac_address_pretty_into_buffer(mac_s));
+  }
   void dump_config() override;
 };
 

esphome/core/helpers.cpp

@@ -638,9 +638,8 @@ std::string get_mac_address() {
 }
 
 std::string get_mac_address_pretty() {
-  uint8_t mac[6];
-  get_mac_address_raw(mac);
-  return format_mac_address_pretty(mac);
+  char buf[18];
+  return std::string(get_mac_address_pretty_into_buffer(buf));
 }
 
 void get_mac_address_into_buffer(std::span<char, 13> buf) {
@@ -649,6 +648,13 @@ void get_mac_address_into_buffer(std::span<char, 13> buf) {
   format_mac_addr_lower_no_sep(mac, buf.data());
 }
 
+const char *get_mac_address_pretty_into_buffer(std::span<char, 18> buf) {
+  uint8_t mac[6];
+  get_mac_address_raw(mac);
+  format_mac_addr_upper(mac, buf.data());
+  return buf.data();
+}
+
 #ifndef USE_ESP32
 bool has_custom_mac_address() { return false; }
 #endif

esphome/core/helpers.h

@@ -1052,6 +1052,11 @@ std::string get_mac_address_pretty();
 /// Assumes buffer length is 13 (12 digits for hexadecimal representation followed by null terminator).
 void get_mac_address_into_buffer(std::span<char, 13> buf);
 
+/// Get the device MAC address into the given buffer, in colon-separated uppercase hex notation.
+/// Buffer must be exactly 18 bytes (17 for "XX:XX:XX:XX:XX:XX" + null terminator).
+/// Returns pointer to the buffer for convenience.
+const char *get_mac_address_pretty_into_buffer(std::span<char, 18> buf);
+
 #ifdef USE_ESP32
 /// Set the MAC address to use from the provided byte array (6 bytes).
 void set_mac_address(uint8_t *mac);