fix: Don't set the Connection header to 'close' if it is already set (#26)

Signed-off-by: Andreas Häber <[email protected]>

Author: ahaeber

src/Docker.DotNet/DockerClient.cs

@@ -386,8 +386,8 @@ internal async Task<WriteClosableStream> MakeRequestForHijackedStreamAsync(
             headers = new Dictionary<string, string>();
         }
 
-        headers.Add("Connection", "tcp");
-        headers.Add("Upgrade", "Upgrade");
+        headers.Add("Upgrade", "tcp");
+        headers.Add("Connection", "Upgrade");
 
         var response = await PrivateMakeRequestAsync(timeout, HttpCompletionOption.ResponseHeadersRead, method, path, queryString, headers, body, cancellationToken)
             .ConfigureAwait(false);

src/Docker.DotNet/Microsoft.Net.Http.Client/ManagedHandler.cs

@@ -141,7 +141,7 @@ private async Task<HttpResponseMessage> ProcessRequestAsync(HttpRequestMessage r
 
         ProcessUrl(request);
         ProcessHostHeader(request);
-        request.Headers.ConnectionClose = true; // TODO: Connection re-use is not supported.
+        request.Headers.ConnectionClose = !request.Headers.Contains("Connection"); // TODO: Connection reuse is not supported.
 
         ProxyMode proxyMode = DetermineProxyModeAndAddressLine(request);
         Socket socket;