Server Side Events (espressif#9222)

* feat: Server Side Events (SSE)

* Update libraries/WiFi/src/WiFiClient.cpp

Co-authored-by: Lucas Saavedra Vaz <32426024+lucasssvaz@users.noreply.github.com>

---------

Co-authored-by: Miquel Martin <miqmago@gmail.com>
Co-authored-by: Miquel <miqmago@users.noreply.github.com>

Author: lucasssvaz

libraries/WebServer/src/WebServer.cpp

@@ -402,6 +402,11 @@ void WebServer::handleClient() {
           _contentLength = CONTENT_LENGTH_NOT_SET;
           _handleRequest();
 
+          if (_currentClient.isSSE()) {
+            _currentStatus = HC_WAIT_CLOSE;
+            _statusChange = millis();
+            keepCurrentClient = true;
+          }
 // Fix for issue with Chrome based browsers: https://github.com/espressif/arduino-esp32/issues/3652
 //           if (_currentClient.connected()) {
 //             _currentStatus = HC_WAIT_CLOSE;
@@ -417,6 +422,10 @@ void WebServer::handleClient() {
       }
       break;
     case HC_WAIT_CLOSE:
+      if (_currentClient.isSSE()) {
+        // Never close connection
+        _statusChange = millis();
+      }
       // Wait for client to close the connection
       if (millis() - _statusChange <= HTTP_MAX_CLOSE_WAIT) {
         keepCurrentClient = true;

libraries/WiFi/src/WiFiClient.cpp

@@ -187,7 +187,7 @@ class WiFiClientSocketHandle {
     }
 };
 
-WiFiClient::WiFiClient():_rxBuffer(nullptr),_connected(false),_timeout(WIFI_CLIENT_DEF_CONN_TIMEOUT_MS),next(NULL)
+WiFiClient::WiFiClient():_rxBuffer(nullptr),_connected(false),_sse(false),_timeout(WIFI_CLIENT_DEF_CONN_TIMEOUT_MS),next(NULL)
 {
 }
 
@@ -347,7 +347,7 @@ int WiFiClient::setOption(int option, int *value)
 
 int WiFiClient::getOption(int option, int *value)
 {
-	socklen_t size = sizeof(int);
+    socklen_t size = sizeof(int);
     int res = getsockopt(fd(), IPPROTO_TCP, option, (char *)value, &size);
     if(res < 0) {
         log_e("fail on fd %d, errno: %d, \"%s\"", fd(), errno, strerror(errno));
@@ -661,3 +661,14 @@ int WiFiClient::fd() const
         return clientSocketHandle->fd();
     }
 }
+
+void WiFiClient::setSSE(bool sse)
+{
+    _sse = sse;
+}
+
+bool WiFiClient::isSSE()
+{
+    return _sse;
+}
+

libraries/WiFi/src/WiFiClient.h

@@ -42,6 +42,7 @@ class WiFiClient : public ESPLwIPClient
     std::shared_ptr<WiFiClientSocketHandle> clientSocketHandle;
     std::shared_ptr<WiFiClientRxBuffer> _rxBuffer;
     bool _connected;
+    bool _sse;
     int _timeout;
     int _lastWriteTimeout;
     int _lastReadTimeout;
@@ -66,6 +67,8 @@ class WiFiClient : public ESPLwIPClient
     void flush();
     void stop();
     uint8_t connected();
+    void setSSE(bool sse);
+    bool isSSE();
 
     operator bool()
     {