implement extraHeaders

Author: doghappy

src/SocketIOClient/SocketIOOptions.cs

@@ -49,6 +49,8 @@ public double RandomizationFactor
             }
         }
 
+        public Dictionary<string, string> ExtraHeaders { get; set; }
+
         public bool AutoUpgrade { get; set; }
     }
 }

src/SocketIOClient/Transport/TransportRouter.cs

@@ -57,6 +57,7 @@ public async Task ConnectAsync()
             Uri uri = UriConverter.GetHandshakeUri(ServerUri, _options.Path, _options.Query);
 
             var req = new HttpRequestMessage(HttpMethod.Get, uri);
+            SetHeaders(req);
 
             var resMsg = await _httpClient.SendAsync(req, new CancellationTokenSource(_options.ConnectionTimeout).Token).ConfigureAwait(false);
             if (!resMsg.IsSuccessStatusCode)
@@ -90,6 +91,17 @@ public async Task ConnectAsync()
             }
         }
 
+        private void SetHeaders(HttpRequestMessage req)
+        {
+            if (_options.ExtraHeaders != null)
+            {
+                foreach (var item in _options.ExtraHeaders)
+                {
+                    req.Headers.Add(item.Key, item.Value);
+                }
+            }
+        }
+
         private async Task WebSocketConnectAsync()
         {
             Uri uri = UriConverter.GetWebSocketUri(ServerUri, _options.Path, _options.Query, Sid);