Exposed sketch MD5 through HTTP headers (#2236)

* Exposed sketch MD5 through HTTP headers

* Updated spacing, docs, example

Author: JeroenVogelpoel

doc/ota_updates/readme.md

@@ -371,6 +371,7 @@ Example header data:
     [HTTP_X_ESP8266_AP_MAC] => 1A:FE:AA:AA:AA:AA
     [HTTP_X_ESP8266_FREE_SPACE] => 671744
     [HTTP_X_ESP8266_SKETCH_SIZE] => 373940
+    [HTTP_X_ESP8266_SKETCH_MD5] => a56f8ef78a0bebd812f62067daf1408a
     [HTTP_X_ESP8266_CHIP_SIZE] => 4194304
     [HTTP_X_ESP8266_SDK_VERSION] => 1.3.0
     [HTTP_X_ESP8266_VERSION] => DOOR-7-g14f53a19
@@ -415,9 +416,9 @@ if(
 	!check_header('HTTP_X_ESP8266_AP_MAC') ||
 	!check_header('HTTP_X_ESP8266_FREE_SPACE') ||
 	!check_header('HTTP_X_ESP8266_SKETCH_SIZE') ||
+	!check_header('HTTP_X_ESP8266_SKETCH_MD5') ||
 	!check_header('HTTP_X_ESP8266_CHIP_SIZE') ||
-	!check_header('HTTP_X_ESP8266_SDK_VERSION') ||
-	!check_header('HTTP_X_ESP8266_VERSION')
+	!check_header('HTTP_X_ESP8266_SDK_VERSION')
 ) {
 	header($_SERVER["SERVER_PROTOCOL"].' 403 Forbidden', true, 403);
 	echo "only for ESP8266 updater! (header)\n";
@@ -429,13 +430,20 @@ $db = array(
 	"18:FE:AA:AA:AA:BB" => "TEMP-1.0.0"
 );
 
-if(isset($db[$_SERVER['HTTP_X_ESP8266_STA_MAC']])) {
-	if($db[$_SERVER['HTTP_X_ESP8266_STA_MAC']] != $_SERVER['HTTP_X_ESP8266_VERSION']) {
-		sendFile("./bin/".$db[$_SERVER['HTTP_X_ESP8266_STA_MAC']]."bin");
-	} else {
-		header($_SERVER["SERVER_PROTOCOL"].' 304 Not Modified', true, 304);
-	}
-	exit();
+if(!isset($db[$_SERVER['HTTP_X_ESP8266_STA_MAC']])) {
+	header($_SERVER["SERVER_PROTOCOL"].' 500 ESP MAC not configured for updates', true, 500);
+}
+
+$localBinary = "./bin/".$db[$_SERVER['HTTP_X_ESP8266_STA_MAC']].".bin";
+
+// Check if version has been set and does not match, if not, check if
+// MD5 hash between local binary and ESP8266 binary do not match if not.
+// then no update has been found.
+if((!check_header('HTTP_X_ESP8266_SDK_VERSION') && $db[$_SERVER['HTTP_X_ESP8266_STA_MAC']] != $_SERVER['HTTP_X_ESP8266_VERSION'])
+	|| $_SERVER["HTTP_X_ESP8266_SKETCH_MD5"] != md5_file($localBinary)) {
+	sendFile($localBinary);
+} else {
+	header($_SERVER["SERVER_PROTOCOL"].' 304 Not Modified', true, 304);
 }
 
 header($_SERVER["SERVER_PROTOCOL"].' 500 no version for ESP MAC', true, 500);

libraries/ESP8266httpUpdate/src/ESP8266httpUpdate.cpp

@@ -175,6 +175,7 @@ HTTPUpdateResult ESP8266HTTPUpdate::handleUpdate(HTTPClient& http, const String&
     http.addHeader(F("x-ESP8266-AP-MAC"), WiFi.softAPmacAddress());
     http.addHeader(F("x-ESP8266-free-space"), String(ESP.getFreeSketchSpace()));
     http.addHeader(F("x-ESP8266-sketch-size"), String(ESP.getSketchSize()));
+    http.addHeader(F("x-ESP8266-sketch-md5"), String(ESP.getSketchMD5()));
     http.addHeader(F("x-ESP8266-chip-size"), String(ESP.getFlashChipRealSize()));
     http.addHeader(F("x-ESP8266-sdk-version"), ESP.getSdkVersion());