WebServer: Use the request's HTTP version and Connection header to set the default keep alive value

Author: ZakCodes

libraries/ESP8266WebServer/src/ESP8266WebServer-impl.h

@@ -320,7 +320,6 @@ void ESP8266WebServerTemplate<ServerType>::handleClient() {
     _currentClient = client;
     _currentStatus = HC_WAIT_READ;
     _statusChange = millis();
-    _keepAlive = true;
   }
 
   bool keepCurrentClient = false;

libraries/ESP8266WebServer/src/ESP8266WebServer.h

@@ -170,8 +170,9 @@ class ESP8266WebServerTemplate
 
   // Whether other requests should be accepted from the client on the
   // same socket after a response is sent.
-  // This will automatically configure the "Connection" header.
-  // Defaults to false.
+  // This will automatically configure the "Connection" header of the response.
+  // Defaults to true when the client's HTTP version is 1.1 or above, otherwise it defaults to false.
+  // If the client sends the "Connection" header, the value given by the header is used.
   void keepAlive(bool keepAlive) { _keepAlive = keepAlive; }
   bool keepAlive() { return _keepAlive; }
 

libraries/ESP8266WebServer/src/Parsing-impl.h

@@ -114,6 +114,9 @@ bool ESP8266WebServerTemplate<ServerType>::_parseRequest(ClientType& client) {
   }
   _currentMethod = method;
 
+  _keepAlive = _currentVersion > 0; // Keep the connection alive by default
+                                    // if the protocol version is greater than HTTP 1.0
+
 #ifdef DEBUG_ESP_HTTP_SERVER
   DEBUG_OUTPUT.print("method: ");
   DEBUG_OUTPUT.print(methodStr);
@@ -177,6 +180,8 @@ bool ESP8266WebServerTemplate<ServerType>::_parseRequest(ClientType& client) {
         contentLength = headerValue.toInt();
       } else if (headerName.equalsIgnoreCase(F("Host"))){
         _hostHeader = headerValue;
+      } else if (headerName.equalsIgnoreCase(F("Connection"))){
+        _keepAlive = headerValue.equalsIgnoreCase(F("keep-alive"));
       }
     }
 
@@ -240,6 +245,8 @@ bool ESP8266WebServerTemplate<ServerType>::_parseRequest(ClientType& client) {
 
       if (headerName.equalsIgnoreCase(F("Host"))){
         _hostHeader = headerValue;
+      } else if (headerName.equalsIgnoreCase(F("Connection"))){
+        _keepAlive = headerValue.equalsIgnoreCase(F("keep-alive"));
       }
     }
     _parseArguments(searchStr);