From 00f22e5c3644f8c645d5741615271b78423ee453 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 27 Oct 2025 14:51:08 -0500
Subject: [PATCH] [network] Eliminate runtime string parsing for IP address
 initialization (#11561)

---
 esphome/components/ethernet/__init__.py | 12 ++++----
 esphome/components/network/__init__.py  | 37 +++++++++++++++++++++++++
 esphome/components/wifi/__init__.py     |  6 ++--
 3 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/esphome/components/ethernet/__init__.py b/esphome/components/ethernet/__init__.py
index 77f70a3630..2f02d227d7 100644
--- a/esphome/components/ethernet/__init__.py
+++ b/esphome/components/ethernet/__init__.py
@@ -14,7 +14,7 @@ from esphome.components.esp32.const import (
     VARIANT_ESP32S2,
     VARIANT_ESP32S3,
 )
-from esphome.components.network import IPAddress
+from esphome.components.network import ip_address_literal
 from esphome.components.spi import CONF_INTERFACE_INDEX, get_spi_interface
 import esphome.config_validation as cv
 from esphome.const import (
@@ -320,11 +320,11 @@ def _final_validate_spi(config):
 def manual_ip(config):
     return cg.StructInitializer(
         ManualIP,
-        ("static_ip", IPAddress(str(config[CONF_STATIC_IP]))),
-        ("gateway", IPAddress(str(config[CONF_GATEWAY]))),
-        ("subnet", IPAddress(str(config[CONF_SUBNET]))),
-        ("dns1", IPAddress(str(config[CONF_DNS1]))),
-        ("dns2", IPAddress(str(config[CONF_DNS2]))),
+        ("static_ip", ip_address_literal(config[CONF_STATIC_IP])),
+        ("gateway", ip_address_literal(config[CONF_GATEWAY])),
+        ("subnet", ip_address_literal(config[CONF_SUBNET])),
+        ("dns1", ip_address_literal(config[CONF_DNS1])),
+        ("dns2", ip_address_literal(config[CONF_DNS2])),
     )
 
 
diff --git a/esphome/components/network/__init__.py b/esphome/components/network/__init__.py
index 1a74350c4c..502803da1e 100644
--- a/esphome/components/network/__init__.py
+++ b/esphome/components/network/__init__.py
@@ -1,3 +1,5 @@
+import ipaddress
+
 import esphome.codegen as cg
 from esphome.components.esp32 import add_idf_sdkconfig_option
 import esphome.config_validation as cv
@@ -10,6 +12,41 @@ AUTO_LOAD = ["mdns"]
 network_ns = cg.esphome_ns.namespace("network")
 IPAddress = network_ns.class_("IPAddress")
 
+
+def ip_address_literal(ip: str | int | None) -> cg.MockObj:
+    """Generate an IPAddress with compile-time initialization instead of runtime parsing.
+
+    This function parses the IP address in Python during code generation and generates
+    a call to the 4-octet constructor (IPAddress(192, 168, 1, 1)) instead of the
+    string constructor (IPAddress("192.168.1.1")). This eliminates runtime string
+    parsing overhead and reduces flash usage on embedded systems.
+
+    Args:
+        ip: IP address as string (e.g., "192.168.1.1"), ipaddress.IPv4Address, or None
+
+    Returns:
+        IPAddress expression that uses 4-octet constructor for efficiency
+    """
+    if ip is None:
+        return IPAddress(0, 0, 0, 0)
+
+    try:
+        # Parse using Python's ipaddress module
+        ip_obj = ipaddress.ip_address(ip)
+    except (ValueError, TypeError):
+        pass
+    else:
+        # Only support IPv4 for now
+        if isinstance(ip_obj, ipaddress.IPv4Address):
+            # Extract octets from the packed bytes representation
+            octets = ip_obj.packed
+            # Generate call to 4-octet constructor: IPAddress(192, 168, 1, 1)
+            return IPAddress(octets[0], octets[1], octets[2], octets[3])
+
+    # Fallback to string constructor if parsing fails
+    return IPAddress(str(ip))
+
+
 CONFIG_SCHEMA = cv.Schema(
     {
         cv.SplitDefault(
diff --git a/esphome/components/wifi/__init__.py b/esphome/components/wifi/__init__.py
index ba488728b7..b980bab4aa 100644
--- a/esphome/components/wifi/__init__.py
+++ b/esphome/components/wifi/__init__.py
@@ -3,7 +3,7 @@ from esphome.automation import Condition
 import esphome.codegen as cg
 from esphome.components.const import CONF_USE_PSRAM
 from esphome.components.esp32 import add_idf_sdkconfig_option, const, get_esp32_variant
-from esphome.components.network import IPAddress
+from esphome.components.network import ip_address_literal
 from esphome.config_helpers import filter_source_files_from_platform
 import esphome.config_validation as cv
 from esphome.config_validation import only_with_esp_idf
@@ -334,9 +334,7 @@ def eap_auth(config):
 
 
 def safe_ip(ip):
-    if ip is None:
-        return IPAddress(0, 0, 0, 0)
-    return IPAddress(str(ip))
+    return ip_address_literal(ip)
 
 
 def manual_ip(config):