[zwave_proxy] Make send_frame safer, make set_home_id protected (#13055)

esphome/components/zwave_proxy/zwave_proxy.cpp

@@ -105,7 +105,7 @@ void ZWaveProxy::process_uart_() {
           this->buffer_[1] >= ZWAVE_MIN_GET_NETWORK_IDS_LENGTH && this->buffer_[0] == ZWAVE_FRAME_TYPE_START) {
         // Store the 4-byte Home ID, which starts at offset 4, and notify connected clients if it changed
         // The frame parser has already validated the checksum and ensured all bytes are present
-        if (this->set_home_id(&this->buffer_[4])) {
+        if (this->set_home_id_(&this->buffer_[4])) {
           this->send_homeid_changed_msg_();
         }
       }
@@ -165,7 +165,7 @@ void ZWaveProxy::zwave_proxy_request(api::APIConnection *api_connection, api::en
   }
 }
 
-bool ZWaveProxy::set_home_id(const uint8_t *new_home_id) {
+bool ZWaveProxy::set_home_id_(const uint8_t *new_home_id) {
   if (std::memcmp(this->home_id_.data(), new_home_id, this->home_id_.size()) == 0) {
     ESP_LOGV(TAG, "Home ID unchanged");
     return false;  // No change
@@ -178,19 +178,28 @@ bool ZWaveProxy::set_home_id(const uint8_t *new_home_id) {
 }
 
 void ZWaveProxy::send_frame(const uint8_t *data, size_t length) {
-  if (length == 1 && data[0] == this->last_response_) {
-    ESP_LOGV(TAG, "Skipping sending duplicate response: 0x%02X", data[0]);
+  // Safety: validate pointer before any access
+  if (data == nullptr) {
+    ESP_LOGE(TAG, "Null data pointer");
     return;
   }
-  if (length && data != nullptr) {
-#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
-    char hex_buf[format_hex_pretty_size(ZWAVE_MAX_LOG_BYTES)];
-#endif
-    ESP_LOGVV(TAG, "Sending: %s", format_hex_pretty_to(hex_buf, data, length));
-    this->write_array(data, length);
-  } else {
-    ESP_LOGE(TAG, "Null pointer or length 0");
+  if (length == 0) {
+    ESP_LOGE(TAG, "Length 0");
+    return;
   }
+
+  // Skip duplicate single-byte responses (ACK/NAK/CAN)
+  if (length == 1 && data[0] == this->last_response_) {
+    ESP_LOGV(TAG, "Response already sent: 0x%02X", data[0]);
+    return;
+  }
+
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
+  char hex_buf[format_hex_pretty_size(ZWAVE_MAX_LOG_BYTES)];
+#endif
+  ESP_LOGVV(TAG, "Sending: %s", format_hex_pretty_to(hex_buf, data, length));
+
+  this->write_array(data, length);
 }
 
 void ZWaveProxy::send_homeid_changed_msg_(api::APIConnection *conn) {

esphome/components/zwave_proxy/zwave_proxy.h

@@ -60,11 +60,11 @@ class ZWaveProxy : public uart::UARTDevice, public Component {
   uint32_t get_home_id() {
     return encode_uint32(this->home_id_[0], this->home_id_[1], this->home_id_[2], this->home_id_[3]);
   }
-  bool set_home_id(const uint8_t *new_home_id);  // Store a new home ID. Returns true if it changed.
 
   void send_frame(const uint8_t *data, size_t length);
 
  protected:
+  bool set_home_id_(const uint8_t *new_home_id);  // Store a new home ID. Returns true if it changed.
   void send_homeid_changed_msg_(api::APIConnection *conn = nullptr);
   void send_simple_command_(uint8_t command_id);
   bool parse_byte_(uint8_t byte);  // Returns true if frame parsing was completed (a frame is ready in the buffer)