Fix support for using proxies with HTTP transport

Author: mconnew

src/System.Private.ServiceModel/src/System/ServiceModel/Channels/HttpChannelFactory.cs

@@ -47,7 +47,6 @@ internal class HttpChannelFactory<TChannel>
         private TransferMode _transferMode;
         private ISecurityCapabilities _securityCapabilities;
         private WebSocketTransportSettings _webSocketSettings;
-        private bool _useDefaultWebProxy;
         private Lazy<string> _webSocketSoapContentType;
         private SHA512 _hashAlgorithm;
         private bool _keepAliveEnabled;
@@ -299,14 +298,19 @@ internal async Task<HttpClient> GetHttpClientAsync(EndpointAddress to,
                 var clientHandler = GetHttpClientHandler(to, clientCertificateToken);
                 clientHandler.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
 
-                if (_proxy != null)
-                {
-                    clientHandler.Proxy = _proxy;
-                }
-                else if (_proxyFactory != null)
+                if (clientHandler.SupportsProxy)
                 {
-                    clientHandler.Proxy = await _proxyFactory.CreateWebProxyAsync(authenticationLevelWrapper.Value,
-                        impersonationLevelWrapper.Value, proxyTokenProvider, cancellationToken);
+                    if (_proxy != null)
+                    {
+                        clientHandler.Proxy = _proxy;
+                        clientHandler.UseProxy = true;
+                    }
+                    else if (_proxyFactory != null)
+                    {
+                        clientHandler.Proxy = await _proxyFactory.CreateWebProxyAsync(authenticationLevelWrapper.Value,
+                            impersonationLevelWrapper.Value, proxyTokenProvider, cancellationToken);
+                        clientHandler.UseProxy = true;
+                    }
                 }
 
                 clientHandler.UseCookies = _allowCookies;
@@ -316,10 +320,6 @@ internal async Task<HttpClient> GetHttpClientAsync(EndpointAddress to,
                 }
 
                 clientHandler.PreAuthenticate = true;
-                if (clientHandler.SupportsProxy)
-                {
-                    clientHandler.UseProxy = _useDefaultWebProxy;
-                }
 
                 clientHandler.UseDefaultCredentials = false;
                 if (credential == CredentialCache.DefaultCredentials)

src/System.Private.ServiceModel/src/System/ServiceModel/Channels/HttpTransportBindingElement.cs

@@ -49,6 +49,8 @@ public HttpTransportBindingElement()
             _maxBufferSize = TransportDefaults.MaxBufferSize;
             _maxPendingAccepts = HttpTransportDefaults.DefaultMaxPendingAccepts;
             _method = string.Empty;
+            _proxyAuthenticationScheme = HttpTransportDefaults.ProxyAuthenticationScheme;
+            _proxyAddress = HttpTransportDefaults.ProxyAddress;
             _realm = HttpTransportDefaults.Realm;
             _requestInitializationTimeout = HttpTransportDefaults.RequestInitializationTimeout;
             _transferMode = HttpTransportDefaults.TransferMode;
@@ -71,14 +73,16 @@ protected HttpTransportBindingElement(HttpTransportBindingElement elementToBeClo
             _maxBufferSizeInitialized = elementToBeCloned._maxBufferSizeInitialized;
             _maxPendingAccepts = elementToBeCloned._maxPendingAccepts;
             _method = elementToBeCloned._method;
+            _proxyAddress = elementToBeCloned._proxyAddress;
+            _proxyAuthenticationScheme = elementToBeCloned._proxyAuthenticationScheme;
             _realm = elementToBeCloned._realm;
             _requestInitializationTimeout = elementToBeCloned._requestInitializationTimeout;
             _transferMode = elementToBeCloned._transferMode;
             _unsafeConnectionNtlmAuthentication = elementToBeCloned._unsafeConnectionNtlmAuthentication;
             _useDefaultWebProxy = elementToBeCloned._useDefaultWebProxy;
             _webSocketSettings = elementToBeCloned._webSocketSettings.Clone();
             _extendedProtectionPolicy = elementToBeCloned.ExtendedProtectionPolicy;
-            this.MessageHandlerFactory = elementToBeCloned.MessageHandlerFactory;
+            MessageHandlerFactory = elementToBeCloned.MessageHandlerFactory;
         }
 
         [DefaultValue(HttpTransportDefaults.AllowCookies)]