feat(server): Expose server tcp state

Author: mathieucarbou

examples/ServerState/ServerState.ino

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// Copyright 2016-2025 Hristo Gochkov, Mathieu Carbou, Emil Muratov
+
+//
+// Server state example
+//
+
+#include <Arduino.h>
+#ifdef ESP32
+#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>
+
+static AsyncWebServer server1(80);
+static AsyncWebServer server2(80);
+
+void setup() {
+  Serial.begin(115200);
+
+#ifndef CONFIG_IDF_TARGET_ESP32H2
+  WiFi.mode(WIFI_AP);
+  WiFi.softAP("esp-captive");
+#endif
+
+  // server state returns one of the tcp_state enum values:
+  // enum tcp_state {
+  //   CLOSED      = 0,
+  //   LISTEN      = 1,
+  //   SYN_SENT    = 2,
+  //   SYN_RCVD    = 3,
+  //   ESTABLISHED = 4,
+  //   FIN_WAIT_1  = 5,
+  //   FIN_WAIT_2  = 6,
+  //   CLOSE_WAIT  = 7,
+  //   CLOSING     = 8,
+  //   LAST_ACK    = 9,
+  //   TIME_WAIT   = 10
+  // };
+
+  assert(server1.state() == tcp_state::CLOSED);
+  assert(server2.state() == tcp_state::CLOSED);
+
+  server1.begin();
+
+  assert(server1.state() == tcp_state::LISTEN);
+  assert(server2.state() == tcp_state::CLOSED);
+
+  server2.begin();
+
+  assert(server1.state() == tcp_state::LISTEN);
+  assert(server2.state() == tcp_state::CLOSED);
+
+  Serial.println("Done!");
+}
+
+void loop() {
+  delay(100);
+}

platformio.ini

@@ -25,6 +25,7 @@ src_dir = examples/PerfTests
 ; src_dir = examples/ResumableDownload
 ; src_dir = examples/Rewrite
 ; src_dir = examples/ServerSentEvents
+; src_dir = examples/ServerState
 ; src_dir = examples/SkipServerMiddleware
 ; src_dir = examples/SlowChunkResponse
 ; src_dir = examples/StaticFile

src/ESPAsyncWebServer.h

@@ -4,9 +4,10 @@
 #ifndef _ESPAsyncWebServer_H_
 #define _ESPAsyncWebServer_H_
 
-#include "Arduino.h"
+#include <Arduino.h>
+#include <FS.h>
+#include <lwip/tcpbase.h>
 
-#include "FS.h"
 #include <algorithm>
 #include <deque>
 #include <functional>
@@ -1075,6 +1076,15 @@ class AsyncWebServer : public AsyncMiddlewareChain {
   void begin();
   void end();
 
+  tcp_state state() const {
+#if defined(ESP8266) || defined(TARGET_RP2040) || defined(TARGET_RP2350) || defined(PICO_RP2040) || defined(PICO_RP2350)
+    // ESPAsyncTCP and RPAsyncTCP methods are not corrected declared with const for immutable ones.
+    return static_cast<tcp_state>(const_cast<AsyncWebServer *>(this)->_server.status());
+#else
+    return static_cast<tcp_state>(_server.status());
+#endif
+  }
+
 #if ASYNC_TCP_SSL_ENABLED
   void onSslFileRequest(AcSSlFileHandler cb, void *arg);
   void beginSecure(const char *cert, const char *private_key_file, const char *password);