Fix NuGet/Home#1158: Basic auth issues with NuGet 3.1.1 in Visual Stu…

…dio 2015.

Note that this issue is related to NuGet/Home#941 (Package restore of universal applications does not work with authenticated feeds).
It was closed as fixed but the fix misses two scenarios:
- The credentials saved in nuget.config is not used.
- The Prompt dialog will not pop up again if user gives the wrong credentials.

src/VsExtension/NuGetPackage.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.ComponentModel.Design;
 using System.Diagnostics;
 using System.Globalization;
@@ -95,12 +96,14 @@ public sealed class NuGetPackage : Package, IVsPackageExtensionProvider, IVsPers
         private NuGetSettings _nugetSettings;
 
         private OutputConsoleLogger _outputConsoleLogger;
+        private HashSet<Uri> _credentialRequested;
 
         public NuGetPackage()
         {
             ServiceLocator.InitializePackageServiceProvider(this);
             StandaloneSwitch.IsRunningStandalone = false;
             _nugetSettings = new NuGetSettings();
+            _credentialRequested = new HashSet<Uri>();
         }
 
         private IVsMonitorSelection VsMonitorSelection
@@ -342,9 +345,10 @@ private void SetDefaultCredentialProvider()
             PackageSourceProvider packageSourceProvider = new PackageSourceProvider(
                 new SettingsToLegacySettings(Settings));
             var visualStudioCredentialProvider = new VisualStudioCredentialProvider(webProxy);
-            HttpClient.DefaultCredentialProvider = new SettingsCredentialProvider(
+            var settingsCredentialProvider = new SettingsCredentialProvider(
                 visualStudioCredentialProvider,
                 packageSourceProvider);
+            HttpClient.DefaultCredentialProvider = settingsCredentialProvider;
 
             // Set up proxy handling for v3 sources.
             // We need to sync the v2 proxy cache and v3 proxy cache so that the user will not
@@ -382,30 +386,21 @@ private void SetDefaultCredentialProvider()
 
             NuGet.Protocol.Core.v3.HttpHandlerResourceV3.PromptForCredentials = uri =>
             {
-                var v2Credentials = v2CredentialStore?.GetCredentials(uri);
-                if (v2Credentials != null)
-                {
-                    // if cached v2 credentials have not been used, try using it first.
-                    return v2Credentials;
-                }
+                bool retrying = _credentialRequested.Contains(uri);
 
-                lock (_credentialsPromptLock)
+                // Add uri to the hashset so that the next we know the credentials for this
+                // uri has been requested before. In this case, a dialog will pop up asking
+                // for credentials.
+                if (!retrying)
                 {
-                    // Retry after we acquire the lock. The credential provider could have been updated while
-                    // we were waiting to acquire it.
-                    v2Credentials = v2CredentialStore?.GetCredentials(uri);
-                    if (v2Credentials != null)
-                    {
-                        // if cached v2 credentials have not been used, try using it first.
-                        return v2Credentials;
-                    }
-
-                    return visualStudioCredentialProvider.GetCredentials(
-                        uri,
-                        proxy: null,
-                        credentialType: CredentialType.RequestCredentials,
-                        retrying: false);
+                    _credentialRequested.Add(uri);
                 }
+
+                return settingsCredentialProvider.GetCredentials(
+                    uri,
+                    proxy: null,
+                    credentialType: CredentialType.RequestCredentials,
+                    retrying: retrying);
             };
 
             NuGet.Protocol.Core.v3.HttpHandlerResourceV3.CredentialsSuccessfullyUsed = (uri, credentials) =>

src/VsExtension/VisualStudioCredentialProvider.cs

@@ -57,21 +57,18 @@ public ICredentials GetCredentials(Uri uri, IWebProxy proxy, CredentialType cred
             {
                 // The cached credentials that we found are not valid so let's ask the user
                 // until they abort or give us valid credentials.
-
-                // Set the static property WebRequest.DefaultWebProxy so that the right host name
-                // is displayed in the UI by IVsWebProxy.
                 var uriToDisplay = uri;
-                if (credentialType == CredentialType.ProxyCredentials)
+                if (credentialType == CredentialType.ProxyCredentials && proxy != null)
                 {
-                    if (proxy != null)
-                    {
-                        // Display the proxy server's host name when asking for proxy credential
-                        uriToDisplay = proxy.GetProxy(uri);
-                    }
-
-                    WebRequest.DefaultWebProxy = new WebProxy(uriToDisplay);
+                    // Display the proxy server's host name when asking for proxy credentials
+                    uriToDisplay = proxy.GetProxy(uri);
                 }
 
+                // Set the static property WebRequest.DefaultWebProxy so that the right host name
+                // is displayed in the UI by IVsWebProxy. Note that this is just a UI thing, 
+                // so this is needed no matter wether we're prompting for proxy credentials 
+                // or request credentials. 
+                WebRequest.DefaultWebProxy = new WebProxy(uriToDisplay);
                 return PromptForCredentials(uri);
             }
             finally