From 013ecfb1896228172dc4f05384da3ae4e7aac8ea Mon Sep 17 00:00:00 2001
From: Will Tatam <will@netmindz.net>
Date: Sun, 9 Nov 2025 09:15:23 +0000
Subject: [PATCH] Add ESP32 bootloader upgrade functionality with JSON API
 support

Co-authored-by: netmindz <442066+netmindz@users.noreply.github.com>
---
 wled00/data/update.htm |  18 ++++++
 wled00/fcn_declare.h   |   3 +
 wled00/json.cpp        |   3 +
 wled00/wled_server.cpp | 141 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 165 insertions(+)

diff --git a/wled00/data/update.htm b/wled00/data/update.htm
index d8b8876e..e93ecde5 100644
--- a/wled00/data/update.htm
+++ b/wled00/data/update.htm
@@ -29,6 +29,13 @@
 					if (data.arch == "esp8266") {
 						toggle('rev');
 					}
+					isESP32 = data.arch && data.arch.startsWith('esp32');
+					if (isESP32) {
+						gId('bootloader-section').style.display = 'block';
+						if (data.bootloaderSHA256) {
+							gId('bootloader-hash').innerText = 'Current bootloader SHA256: ' + data.bootloaderSHA256;
+						}
+					}
 				})
 				.catch(error => {
 					console.log('Could not fetch device info:', error);
@@ -37,6 +44,7 @@
 					document.querySelector('.release-name').textContent = 'Unknown';
 				});
 		}
+		function GetV() {/*injected values here*/}
 	</script>
 	<style>
 		@import url("style.css");
@@ -60,6 +68,16 @@
 		<button id="rev" type="button" onclick="cR()">Revert update</button><br>
 		<button type="button" onclick="B()">Back</button>
 	</form>
+	<div id="bootloader-section" style="display:none;">
+		<hr class="sml">
+		<h2>ESP32 Bootloader Update</h2>
+		<div id="bootloader-hash" class="sip" style="margin-bottom:8px;"></div>
+		<form method='POST' action='./updatebootloader' id='bootupd' enctype='multipart/form-data' onsubmit="toggle('bootupd')">
+			<b>Warning:</b> Only upload verified ESP32 bootloader files!<br>
+			<input type='file' name='update' required><br>
+			<button type="submit">Update Bootloader</button>
+		</form>
+	</div>
 	<div id="Noupd" class="hide"><b>Updating...</b><br>Please do not close or refresh the page :)</div>
 </body>
 </html>
\ No newline at end of file
diff --git a/wled00/fcn_declare.h b/wled00/fcn_declare.h
index 01c2c2ec..0b557d45 100644
--- a/wled00/fcn_declare.h
+++ b/wled00/fcn_declare.h
@@ -546,6 +546,9 @@ void serveMessage(AsyncWebServerRequest* request, uint16_t code, const String& h
 void serveJsonError(AsyncWebServerRequest* request, uint16_t code, uint16_t error);
 void serveSettings(AsyncWebServerRequest* request, bool post = false);
 void serveSettingsJS(AsyncWebServerRequest* request);
+#if defined(ARDUINO_ARCH_ESP32) && !defined(WLED_DISABLE_OTA)
+String getBootloaderSHA256Hex();
+#endif
 
 //ws.cpp
 void handleWs();
diff --git a/wled00/json.cpp b/wled00/json.cpp
index 82043194..a5ef7475 100644
--- a/wled00/json.cpp
+++ b/wled00/json.cpp
@@ -820,6 +820,9 @@ void serializeInfo(JsonObject root)
   root[F("resetReason1")] = (int)rtc_get_reset_reason(1);
   #endif
   root[F("lwip")] = 0; //deprecated
+  #ifndef WLED_DISABLE_OTA
+  root[F("bootloaderSHA256")] = getBootloaderSHA256Hex();
+  #endif
 #else
   root[F("arch")] = "esp8266";
   root[F("core")] = ESP.getCoreVersion();
diff --git a/wled00/wled_server.cpp b/wled00/wled_server.cpp
index 10397477..49e0c485 100644
--- a/wled00/wled_server.cpp
+++ b/wled00/wled_server.cpp
@@ -15,6 +15,13 @@
 #include "html_cpal.h"
 #include "html_edit.h"
 
+#if defined(ARDUINO_ARCH_ESP32) && !defined(WLED_DISABLE_OTA)
+  #include <esp_partition.h>
+  #include <esp_ota_ops.h>
+  #include <bootloader_common.h>
+  #include <mbedtls/sha256.h>
+#endif
+
 // define flash strings once (saves flash memory)
 static const char s_redirecting[] PROGMEM = "Redirecting...";
 static const char s_content_enc[] PROGMEM = "Content-Encoding";
@@ -32,6 +39,12 @@ static const char s_no_store[]       PROGMEM = "no-store";
 static const char s_expires[]        PROGMEM = "Expires";
 static const char _common_js[]       PROGMEM = "/common.js";
 
+#if defined(ARDUINO_ARCH_ESP32) && !defined(WLED_DISABLE_OTA)
+// Cache for bootloader SHA256 digest
+static uint8_t bootloaderSHA256[32];
+static bool bootloaderSHA256Cached = false;
+#endif
+
 //Is this an IP?
 static bool isIp(const String &str) {
   for (size_t i = 0; i < str.length(); i++) {
@@ -180,6 +193,61 @@ static String msgProcessor(const String& var)
   return String();
 }
 
+#if defined(ARDUINO_ARCH_ESP32) && !defined(WLED_DISABLE_OTA)
+// Calculate and cache the bootloader SHA256 digest
+static void calculateBootloaderSHA256() {
+  if (bootloaderSHA256Cached) return;
+  
+  // Bootloader is at fixed offset 0x1000 (4KB) and is typically 32KB
+  const uint32_t bootloaderOffset = 0x1000;
+  const uint32_t bootloaderSize = 0x8000; // 32KB, typical bootloader size
+  
+  mbedtls_sha256_context ctx;
+  mbedtls_sha256_init(&ctx);
+  mbedtls_sha256_starts(&ctx, 0); // 0 = SHA256 (not SHA224)
+  
+  const size_t chunkSize = 256;
+  uint8_t buffer[chunkSize];
+  
+  for (uint32_t offset = 0; offset < bootloaderSize; offset += chunkSize) {
+    size_t readSize = min(chunkSize, bootloaderSize - offset);
+    if (esp_flash_read(NULL, buffer, bootloaderOffset + offset, readSize) == ESP_OK) {
+      mbedtls_sha256_update(&ctx, buffer, readSize);
+    }
+  }
+  
+  mbedtls_sha256_finish(&ctx, bootloaderSHA256);
+  mbedtls_sha256_free(&ctx);
+  bootloaderSHA256Cached = true;
+}
+
+// Get bootloader SHA256 as hex string
+static String getBootloaderSHA256Hex() {
+  calculateBootloaderSHA256();
+  
+  char hex[65];
+  for (int i = 0; i < 32; i++) {
+    sprintf(hex + (i * 2), "%02x", bootloaderSHA256[i]);
+  }
+  hex[64] = '\0';
+  return String(hex);
+}
+
+// Verify if uploaded data is a valid ESP32 bootloader
+static bool isValidBootloader(const uint8_t* data, size_t len) {
+  if (len < 32) return false;
+  
+  // Check for ESP32 bootloader magic byte (0xE9)
+  if (data[0] != 0xE9) return false;
+  
+  // Additional validation: check segment count is reasonable
+  uint8_t segmentCount = data[1];
+  if (segmentCount > 16) return false;
+  
+  return true;
+}
+#endif
+
 static void handleUpload(AsyncWebServerRequest *request, const String& filename, size_t index, uint8_t *data, size_t len, bool isFinal) {
   if (!correctPIN) {
     if (isFinal) request->send(401, FPSTR(CONTENT_TYPE_PLAIN), FPSTR(s_unlock_cfg));
@@ -527,6 +595,79 @@ void initServer()
   server.on(_update, HTTP_POST, notSupported, [](AsyncWebServerRequest *request, String filename, size_t index, uint8_t *data, size_t len, bool isFinal){});
 #endif
 
+#if defined(ARDUINO_ARCH_ESP32) && !defined(WLED_DISABLE_OTA)
+  // ESP32 bootloader update endpoint
+  server.on(F("/updatebootloader"), HTTP_POST, [](AsyncWebServerRequest *request){
+    if (!correctPIN) {
+      serveSettings(request, true); // handle PIN page POST request
+      return;
+    }
+    if (otaLock) {
+      serveMessage(request, 401, FPSTR(s_accessdenied), FPSTR(s_unlock_ota), 254);
+      return;
+    }
+    if (Update.hasError()) {
+      serveMessage(request, 500, F("Bootloader update failed!"), F("Please check your file and retry!"), 254);
+    } else {
+      serveMessage(request, 200, F("Bootloader updated successfully!"), FPSTR(s_rebooting), 131);
+      doReboot = true;
+    }
+  },[](AsyncWebServerRequest *request, String filename, size_t index, uint8_t *data, size_t len, bool isFinal){
+    IPAddress client = request->client()->remoteIP();
+    if (((otaSameSubnet && !inSameSubnet(client)) && !strlen(settingsPIN)) || (!otaSameSubnet && !inLocalSubnet(client))) {
+      DEBUG_PRINTLN(F("Attempted bootloader update from different/non-local subnet!"));
+      request->send(401, FPSTR(CONTENT_TYPE_PLAIN), FPSTR(s_accessdenied));
+      return;
+    }
+    if (!correctPIN || otaLock) return;
+    
+    if (!index) {
+      DEBUG_PRINTLN(F("Bootloader Update Start"));
+      #if WLED_WATCHDOG_TIMEOUT > 0
+      WLED::instance().disableWatchdog();
+      #endif
+      lastEditTime = millis(); // make sure PIN does not lock during update
+      strip.suspend();
+      strip.resetSegments();
+      
+      // Begin bootloader update - use U_FLASH and specify bootloader partition offset
+      if (!Update.begin(0x8000, U_FLASH, -1, 0x1000)) {
+        DEBUG_PRINTLN(F("Bootloader Update Begin Failed"));
+        Update.printError(Serial);
+      }
+    }
+    
+    // Verify bootloader magic on first chunk
+    if (index == 0 && !isValidBootloader(data, len)) {
+      DEBUG_PRINTLN(F("Invalid bootloader file!"));
+      Update.abort();
+      strip.resume();
+      #if WLED_WATCHDOG_TIMEOUT > 0
+      WLED::instance().enableWatchdog();
+      #endif
+      return;
+    }
+    
+    if (!Update.hasError()) {
+      Update.write(data, len);
+    }
+    
+    if (isFinal) {
+      if (Update.end(true)) {
+        DEBUG_PRINTLN(F("Bootloader Update Success"));
+        bootloaderSHA256Cached = false; // Invalidate cached bootloader hash
+      } else {
+        DEBUG_PRINTLN(F("Bootloader Update Failed"));
+        Update.printError(Serial);
+        strip.resume();
+        #if WLED_WATCHDOG_TIMEOUT > 0
+        WLED::instance().enableWatchdog();
+        #endif
+      }
+    }
+  });
+#endif
+
 #ifdef WLED_ENABLE_DMX
   server.on(F("/dmxmap"), HTTP_GET, [](AsyncWebServerRequest *request){
     request->send_P(200, FPSTR(CONTENT_TYPE_HTML), PAGE_dmxmap, dmxProcessor);