From e711cd0e417fc7ed241fa5a20ca7162c603d0de0 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Fri, 26 Dec 2025 13:39:57 -1000
Subject: [PATCH] dry it up

---
 .../ethernet/ethernet_component.cpp           | 21 ++++++++++---------
 .../components/ethernet/ethernet_component.h  |  2 ++
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/esphome/components/ethernet/ethernet_component.cpp b/esphome/components/ethernet/ethernet_component.cpp
index c20f08ed82..114000401f 100644
--- a/esphome/components/ethernet/ethernet_component.cpp
+++ b/esphome/components/ethernet/ethernet_component.cpp
@@ -671,17 +671,13 @@ void EthernetComponent::dump_connect_params_() {
   }
 #endif /* USE_NETWORK_IPV6 */
 
-  // Use stack buffer for MAC address formatting to avoid heap allocation
-  uint8_t mac[6];
-  char mac_buf[18];
-  get_eth_mac_address_raw(mac);
-  format_mac_addr_upper(mac, mac_buf);
+  char mac_buf[MAC_ADDRESS_PRETTY_BUFFER_SIZE];
   ESP_LOGCONFIG(TAG,
                 "  MAC Address: %s\n"
                 "  Is Full Duplex: %s\n"
                 "  Link Speed: %u",
-                mac_buf, YESNO(this->get_duplex_mode() == ETH_DUPLEX_FULL),
-                this->get_link_speed() == ETH_SPEED_100M ? 100 : 10);
+                this->get_eth_mac_address_pretty_into_buffer(mac_buf),
+                YESNO(this->get_duplex_mode() == ETH_DUPLEX_FULL), this->get_link_speed() == ETH_SPEED_100M ? 100 : 10);
 }
 
 #ifdef USE_ETHERNET_SPI
@@ -722,11 +718,16 @@ void EthernetComponent::get_eth_mac_address_raw(uint8_t *mac) {
 }
 
 std::string EthernetComponent::get_eth_mac_address_pretty() {
+  char buf[MAC_ADDRESS_PRETTY_BUFFER_SIZE];
+  return std::string(this->get_eth_mac_address_pretty_into_buffer(buf));
+}
+
+const char *EthernetComponent::get_eth_mac_address_pretty_into_buffer(
+    std::span<char, MAC_ADDRESS_PRETTY_BUFFER_SIZE> buf) {
   uint8_t mac[6];
   get_eth_mac_address_raw(mac);
-  char buf[18];
-  format_mac_addr_upper(mac, buf);
-  return std::string(buf);
+  format_mac_addr_upper(mac, buf.data());
+  return buf.data();
 }
 
 eth_duplex_t EthernetComponent::get_duplex_mode() {
diff --git a/esphome/components/ethernet/ethernet_component.h b/esphome/components/ethernet/ethernet_component.h
index bffed4dc4a..490a9d026e 100644
--- a/esphome/components/ethernet/ethernet_component.h
+++ b/esphome/components/ethernet/ethernet_component.h
@@ -3,6 +3,7 @@
 #include "esphome/core/component.h"
 #include "esphome/core/defines.h"
 #include "esphome/core/hal.h"
+#include "esphome/core/helpers.h"
 #include "esphome/components/network/ip_address.h"
 
 #ifdef USE_ESP32
@@ -93,6 +94,7 @@ class EthernetComponent : public Component {
   void set_use_address(const char *use_address);
   void get_eth_mac_address_raw(uint8_t *mac);
   std::string get_eth_mac_address_pretty();
+  const char *get_eth_mac_address_pretty_into_buffer(std::span<char, MAC_ADDRESS_PRETTY_BUFFER_SIZE> buf);
   eth_duplex_t get_duplex_mode();
   eth_speed_t get_link_speed();
   bool powerdown();