From 97a18717e6d3b39a281cd1403d03a304404321a0 Mon Sep 17 00:00:00 2001
From: Oxan van Leeuwen <oxan@oxanvanleeuwen.nl>
Date: Mon, 13 Sep 2021 02:44:39 +0200
Subject: [PATCH] Disable automatic usage of SNTP servers from DHCP (#2273)

---
 esphome/components/wifi/wifi_component_esp32.cpp   | 6 ++++++
 esphome/components/wifi/wifi_component_esp8266.cpp | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/esphome/components/wifi/wifi_component_esp32.cpp b/esphome/components/wifi/wifi_component_esp32.cpp
index 57c4efcdd5..b56030db56 100644
--- a/esphome/components/wifi/wifi_component_esp32.cpp
+++ b/esphome/components/wifi/wifi_component_esp32.cpp
@@ -11,6 +11,7 @@
 #endif
 #include "lwip/err.h"
 #include "lwip/dns.h"
+#include "lwip/apps/sntp.h"
 
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
@@ -92,6 +93,11 @@ bool WiFiComponent::wifi_sta_ip_config_(optional<ManualIP> manual_ip) {
   tcpip_adapter_dhcp_status_t dhcp_status;
   tcpip_adapter_dhcpc_get_status(TCPIP_ADAPTER_IF_STA, &dhcp_status);
   if (!manual_ip.has_value()) {
+    // lwIP starts the SNTP client if it gets an SNTP server from DHCP. We don't need the time, and more importantly,
+    // the built-in SNTP client has a memory leak in certain situations. Disable this feature.
+    // https://github.com/esphome/issues/issues/2299
+    sntp_servermode_dhcp(false);
+
     // Use DHCP client
     if (dhcp_status != TCPIP_ADAPTER_DHCP_STARTED) {
       esp_err_t err = tcpip_adapter_dhcpc_start(TCPIP_ADAPTER_IF_STA);
diff --git a/esphome/components/wifi/wifi_component_esp8266.cpp b/esphome/components/wifi/wifi_component_esp8266.cpp
index ad1a64d1f4..de529ee3aa 100644
--- a/esphome/components/wifi/wifi_component_esp8266.cpp
+++ b/esphome/components/wifi/wifi_component_esp8266.cpp
@@ -16,6 +16,7 @@ extern "C" {
 #include "lwip/dns.h"
 #include "lwip/dhcp.h"
 #include "lwip/init.h"  // LWIP_VERSION_
+#include "lwip/apps/sntp.h"
 #if LWIP_IPV6
 #include "lwip/netif.h"  // struct netif
 #endif
@@ -112,6 +113,11 @@ bool WiFiComponent::wifi_sta_ip_config_(optional<ManualIP> manual_ip) {
 
   enum dhcp_status dhcp_status = wifi_station_dhcpc_status();
   if (!manual_ip.has_value()) {
+    // lwIP starts the SNTP client if it gets an SNTP server from DHCP. We don't need the time, and more importantly,
+    // the built-in SNTP client has a memory leak in certain situations. Disable this feature.
+    // https://github.com/esphome/issues/issues/2299
+    sntp_servermode_dhcp(false);
+
     // Use DHCP client
     if (dhcp_status != DHCP_STARTED) {
       bool ret = wifi_station_dhcpc_start();