Add files via upload

Author: JosePineiro

src/AsyncWebServerRequest.cpp

@@ -1,5 +1,23 @@
  #include <ESPAsyncWebServer.h>
 
+ /**
+ * @brief Sends a file from the filesystem to the client, with optional gzip compression and ETag-based caching.
+ * 
+ * This method serves files over HTTP from the provided filesystem. If a compressed version of the file 
+ * (with a `.gz` extension) exists and the `download` flag is not set, it serves the compressed file. 
+ * It also handles ETag caching using the CRC32 value from the gzip trailer, responding with `304 Not Modified`
+ * if the client's `If-None-Match` header matches the generated ETag.
+ * 
+ * @param fs Reference to the filesystem (SPIFFS, LittleFS, etc.).
+ * @param path Path to the file to be served.
+ * @param contentType Optional MIME type of the file to be sent.
+ *                    If contentType is "" it will be obtained from the file extension
+ * @param download If true, forces the file to be sent as a download (disables gzip compression).
+ * @param callback Optional template processor for dynamic content generation.
+ *                 Templates will not be processed in compressed files.
+ * 
+ * @note If neither the file nor its compressed version exists, responds with `404 Not Found`.
+ */
  void AsyncWebServerRequest::send(FS &fs, const String &path, const char *contentType, bool download, AwsTemplateProcessor callback) {
     const String gzPath = path + asyncsrv::T__gz;
     const bool useCompressedVersion  = !download && fs.exists(gzPath);
@@ -13,7 +31,7 @@
 
         uint8_t crcFromGzipTrailer[4];
         if (file.read(crcFromGzipTrailer, sizeof(crcFromGzipTrailer)) == sizeof(crcFromGzipTrailer)) {
-          char serverETag[11]; // " + 8 hex chars + " + '\0'
+          char serverETag[9];
           _getEtag(crcFromGzipTrailer, serverETag);
 
           // Compare with client's If-None-Match header
@@ -42,24 +60,22 @@
  * This function converts a 4-byte array into a hexadecimal ETag string enclosed in quotes.
  *  
  * @param trailer[4] Input array of 4 bytes to convert to hexadecimal
- * @param serverETag Output buffer that must be at least 11 bytes long to store the ETag
- *                   Must be pre-allocated with minimum 11 bytes (8 hex + 2 quotes + 1 null terminator)
+ * @param serverETag Output buffer to store the ETag
+ *                   Must be pre-allocated with minimum 9 bytes (8 hex + 1 null terminator)
  */
 void AsyncWebServerRequest::_getEtag(uint8_t trailer[4], char* serverETag) {
   static constexpr char hexChars[] = "0123456789ABCDEF";
 
   uint32_t data;
   memcpy(&data, trailer, 4);
 
-  serverETag[0] = '"';
-  serverETag[1] = hexChars[(data >> 4) & 0x0F];
-  serverETag[2] = hexChars[data & 0x0F];
-  serverETag[3] = hexChars[(data >> 12) & 0x0F];
-  serverETag[4] = hexChars[(data >> 8) & 0x0F];
-  serverETag[5] = hexChars[(data >> 20) & 0x0F];
-  serverETag[6] = hexChars[(data >> 16) & 0x0F];
-  serverETag[7] = hexChars[(data >> 28)];
-  serverETag[8] = hexChars[(data >> 24) & 0x0F];
-  serverETag[9] = '"';
-  serverETag[10] = '\0';
+  serverETag[0] = hexChars[(data >> 4) & 0x0F];
+  serverETag[1] = hexChars[data & 0x0F];
+  serverETag[2] = hexChars[(data >> 12) & 0x0F];
+  serverETag[3] = hexChars[(data >> 8) & 0x0F];
+  serverETag[4] = hexChars[(data >> 20) & 0x0F];
+  serverETag[5] = hexChars[(data >> 16) & 0x0F];
+  serverETag[6] = hexChars[(data >> 28)];
+  serverETag[7] = hexChars[(data >> 24) & 0x0F];
+  serverETag[8] = '\0';
 }

src/WebResponses.cpp

@@ -688,7 +688,7 @@ AsyncFileResponse::AsyncFileResponse(FS &fs, const String &path, const char *con
     _content.seek(_contentLength - 8);
     uint8_t crcInTrailer[4];
     if (_content.read(crcInTrailer, sizeof(crcInTrailer)) == sizeof(crcInTrailer)) {
-      char serverETag[11];
+      char serverETag[9];
       AsyncWebServerRequest::_getEtag(crcInTrailer, serverETag);
       addHeader(T_ETag, serverETag, false);
       addHeader(T_Cache_Control, T_no_cache, false);