Support chunked encoding in requests

examples/ChunkRequest/ChunkRequest.ino

@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// Copyright 2016-2026 Hristo Gochkov, Mathieu Carbou, Emil Muratov, Mitch Bradley
+
+//
+// - Test for chunked encoding in requests
+//
+
+#include <Arduino.h>
+#if defined(ESP32) || defined(LIBRETINY)
+#include <AsyncTCP.h>
+#include <WiFi.h>
+#elif defined(ESP8266)
+#include <ESP8266WiFi.h>
+#include <ESPAsyncTCP.h>
+#elif defined(TARGET_RP2040) || defined(TARGET_RP2350) || defined(PICO_RP2040) || defined(PICO_RP2350)
+#include <RPAsyncTCP.h>
+#include <WiFi.h>
+#endif
+
+#include <ESPAsyncWebServer.h>
+#include <LittleFS.h>
+
+using namespace asyncsrv;
+
+// Tests:
+//
+// Upload a file with PUT
+//   curl -T myfile.txt http://192.168.4.1/
+//
+// Upload a file with PUT using chunked encoding
+//   curl -T bigfile.txt -H 'Transfer-Encoding: chunked' http://192.168.4.1/
+//   ** Note: If the file will not fit in the available space, the server
+//   ** does not know that in advance due to the lack of a Content-Length header.
+//   ** The transfer will proceed until the filesystem fills up, then the transfer
+//   ** will fail and the partial file will be deleted.  This works correctly with
+//   ** recent versions (e.g. pioarduino) of the arduinoespressif32 framework, but
+//   ** fails with the stale 3.20017.241212+sha.dcc1105b version due to a LittleFS
+//   ** bug that has since been fixed.
+//
+// Immediately reject a chunked PUT that will not fit in available space
+//   curl -T bigfile.txt -H 'Transfer-Encoding: chunked' -H 'X-Expected-Entity-Length: 99999999' http://192.168.4.1/
+//   ** Note: MacOS WebDAVFS supplies the X-Expected-Entity-Length header with its
+//   ** chunked PUTs
+// Malformed chunk (triggers abort)
+//   printf 'PUT /bad HTTP/1.1\r\nTransfer-Encoding: chunked\r\n\r\n5\r\n12345\r\nZ\r\n' | nc 192.168.4.1 80
+
+// This struct is used with _tempObject to communicate between handleBody and a subsequent handleRequest
+struct RequestState {
+  File outFile;
+};
+
+void handleRequest(AsyncWebServerRequest *request) {
+  Serial.print(request->methodToString());
+  Serial.print(" ");
+  Serial.println(request->url());
+
+  if (request->method() != HTTP_PUT) {
+    request->send(400);  // Bad Request
+    return;
+  }
+
+  // If request->_tempObject is not null, handleBody already
+  // did the necessary work for a PUT operation.  Otherwise,
+  // handleBody was either not called, or did nothing, so we
+  // handle the request later in this routine.  That happens
+  // when a non-chunked PUT has Content-Length: 0.
+  auto state = static_cast<RequestState *>(request->_tempObject);
+  if (state) {
+    // If handleBody successfully opened the file, whether or not it
+    // wrote data to it, we close it here and send the "created"
+    // response.  If handleBody did not open the file, because the
+    // open attempt failed or because the operation was rejected,
+    // state will be non-null but state->outFile will be false.  In
+    // that case, handleBody has already sent an appropriate
+    // response code.
+
+    if (state->outFile) {
+      // The file was already opened and written in handleBody so
+      // we close it here and issue the appropriate response.
+      state->outFile.close();
+      request->send(201);  // Created
+    }
+    // The resources used by state will be automatically freed
+    // when the framework frees the _tempObject pointer
+    return;
+  }
+
+  String path = request->url();
+
+  // This PUT code executes if the body was empty, which
+  // can happen if the client creates a zero-length file.
+  // MacOS WebDAVFS does that, then later LOCKs the file
+  // and issues a subsequent PUT with body contents.
+
+#ifdef ESP32
+  File file = LittleFS.open(path, "w", true);
+#else
+  File file = LittleFS.open(path, "w");
+#endif
+
+  if (file) {
+    file.close();
+    request->send(201);  // Created
+    return;
+  }
+  request->send(403);
+}
+
+void handleBody(AsyncWebServerRequest *request, uint8_t *data, size_t len, size_t index, size_t total) {
+  if (request->method() == HTTP_PUT) {
+    auto state = static_cast<RequestState *>(request->_tempObject);
+    if (index == 0) {
+      // parse the url to a proper path
+      String path = request->url();
+
+      // Allocate the _tempObject memory
+      request->_tempObject = std::malloc(sizeof(RequestState));
+
+      // Use placement new to construct the RequestState object therein
+      state = new (request->_tempObject) RequestState{File()};
+
+      // If the client disconnects or there is a parsing error,
+      // handleRequest will not be called so we need to close
+      // the file.  The memory backing _tempObject will be freed
+      // automatically.
+      request->onDisconnect([request]() {
+        Serial.println("Client disconnected");
+        auto state = static_cast<RequestState *>(request->_tempObject);
+        if (state) {
+          if (state->outFile) {
+            state->outFile.close();
+          }
+        }
+      });
+
+      if (total) {
+#ifdef ESP32
+        size_t avail = LittleFS.totalBytes() - LittleFS.usedBytes();
+#else
+        FSInfo info;
+        LittleFS.info(info);
+        auto avail = info.totalBytes - info.usedBytes;
+#endif
+        avail = (avail >= 4096) ? avail - 4096 : avail;  // Reserve a block for overhead
+        if (total > avail) {
+          Serial.printf("PUT %zu bytes will not fit in available space (%zu).\n", total, avail);
+          request->send(507, "text/plain", "Too large for available storage\r\n");
+          return;
+        }
+      }
+      Serial.print("Opening ");
+      Serial.print(path);
+      Serial.println(" from handleBody");
+#ifdef ESP32
+      File file = LittleFS.open(path, "w", true);
+#else
+      File file = LittleFS.open(path, "w");
+#endif
+      if (!file) {
+        request->send(500, "text/plain", "Cannot create the file");
+        return;
+      }
+      if (file.isDirectory()) {
+        file.close();
+        Serial.println("Cannot PUT to a directory");
+        request->send(403, "text/plain", "Cannot PUT to a directory");
+        return;
+      }
+      // If we already returned, the File object in
+      // request->_tempObject is the default-constructed one.  The
+      // presence of a non-default-constructed File in state->outFile
+      // indicates that the file was opened successfully and is ready
+      // to receive body data.  The File will be closed later when
+      // handleRequest is called after all calls to handleBody
+
+      std::swap(state->outFile, file);
+      // Now request->_tempObject contains the actual file object which owns it,
+      // and default-constructed File() object is in file, which will
+      // go out of scope
+    }
+    if (state && state->outFile) {
+      Serial.printf("Writing %zu bytes at offset %zu\n", len, index);
+      auto actual = state->outFile.write(data, len);
+      if (actual != len) {
+        Serial.println("WebDAV write failed.  Deleting file.");
+
+        // Replace the File object in state with a null one
+        File file{};
+        std::swap(state->outFile, file);
+        file.close();
+
+        String path = request->url();
+        LittleFS.remove(path);
+        request->send(507, "text/plain", "Too large for available storage\r\n");
+        return;
+      }
+    }
+  }
+}
+
+static AsyncWebServer server(80);
+
+void setup() {
+  Serial.begin(115200);
+
+#if ASYNCWEBSERVER_WIFI_SUPPORTED
+  WiFi.mode(WIFI_AP);
+  WiFi.softAP("esp-captive");
+#endif
+
+#ifdef ESP32
+  LittleFS.begin(true);
+#else
+  LittleFS.begin();
+#endif
+
+  server.onRequestBody(handleBody);
+  server.onNotFound(handleRequest);
+
+  server.begin();
+}
+
+void loop() {
+  delay(100);
+}

platformio.ini

@@ -6,6 +6,7 @@ lib_dir = .
 ; src_dir = examples/Auth
 ; src_dir = examples/CaptivePortal
 ; src_dir = examples/CatchAllHandler
+; src_dir = examples/ChunkRequest
 ; src_dir = examples/ChunkResponse
 ; src_dir = examples/ChunkRetryResponse
 ; src_dir = examples/CORS

src/AsyncJson.cpp

@@ -200,6 +200,17 @@ void AsyncCallbackJsonWebHandler::handleBody(AsyncWebServerRequest *request, uin
     }
 
     if (index == 0) {
+      if (total == 0) {
+        // If total is 0, it is probably a chunked request without an
+        // X-Expected-Entity-Length header.  In that case there is
+        // no way to know the actual length in advance.  The best
+        // way to handle this would be to use a String instead of
+        // a fixed-length buffer, but for now we just reject.
+        async_ws_log_e("AsyncJson cannot handle chunked requests without X-Expected-Entity-Length");
+        request->abort();
+        return;
+      }
+
       // this check allows request->_tempObject to be initialized from a middleware
       if (request->_tempObject == NULL) {
         request->_tempObject = calloc(total + 1, sizeof(uint8_t));  // null-terminated string

src/ESPAsyncWebServer.h

@@ -280,6 +280,13 @@ class AsyncWebServerRequest {
   size_t _itemBufferIndex;
   bool _itemIsFile;
 
+  size_t _chunkStartIndex;  // Offset from start of the chunked data stream
+  size_t _chunkOffset;      // Offset into the current chunk
+  size_t _chunkSize;        // Size of the current chunk
+  uint8_t _chunkedParseState;
+  uint8_t _chunkedLastChar;
+  bool _parseChunkedBytes(uint8_t *data, size_t len);
+
   void _onPoll();
   void _onAck(size_t len, uint32_t time);
   void _onError(int8_t error);