Implement public client application global cache (#770)

Author: cheenamalhotra

src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ActiveDirectoryAuthenticationProvider.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Collections.Concurrent;
 using System.Linq;
 using System.Security;
 using System.Threading;
@@ -15,6 +16,14 @@ namespace Microsoft.Data.SqlClient
     /// <include file='../../../../../../doc/snippets/Microsoft.Data.SqlClient/ActiveDirectoryAuthenticationProvider.xml' path='docs/members[@name="ActiveDirectoryAuthenticationProvider"]/ActiveDirectoryAuthenticationProvider/*'/>
     public sealed class ActiveDirectoryAuthenticationProvider : SqlAuthenticationProvider
     {
+        /// <summary>
+        /// This is a static cache instance meant to hold instances of "PublicClientApplication" mapping to information available in PublicClientAppKey.
+        /// The purpose of this cache is to allow re-use of Access Tokens fetched for a user interactively or with any other mode
+        /// to avoid interactive authentication request every-time, within application scope making use of MSAL's userTokenCache.
+        /// </summary>
+        private static ConcurrentDictionary<PublicClientAppKey, IPublicClientApplication> s_pcaMap
+            = new ConcurrentDictionary<PublicClientAppKey, IPublicClientApplication>();
+        private static readonly string s_nativeClientRedirectUri = "https://login.microsoftonline.com/common/oauth2/nativeclient";
         private static readonly string s_defaultScopeSuffix = "/.default";
         private readonly string _type = typeof(ActiveDirectoryAuthenticationProvider).Name;
         private readonly SqlClientLogger _logger = new SqlClientLogger();
@@ -67,10 +76,10 @@ public override void BeforeUnload(SqlAuthenticationMethod authentication)
         }
 
 #if NETSTANDARD
-        private Func<object> parentActivityOrWindowFunc = null;
+        private Func<object> _parentActivityOrWindowFunc = null;
 
         /// <include file='../../../../../../doc/snippets/Microsoft.Data.SqlClient/ActiveDirectoryAuthenticationProvider.xml' path='docs/members[@name="ActiveDirectoryAuthenticationProvider"]/SetParentActivityOrWindowFunc/*'/>
-        public void SetParentActivityOrWindowFunc(Func<object> parentActivityOrWindowFunc) => this.parentActivityOrWindowFunc = parentActivityOrWindowFunc;
+        public void SetParentActivityOrWindowFunc(Func<object> parentActivityOrWindowFunc) => this._parentActivityOrWindowFunc = parentActivityOrWindowFunc;
 #endif
 
 #if NETFRAMEWORK
@@ -108,51 +117,24 @@ public override Task<SqlAuthenticationToken> AcquireTokenAsync(SqlAuthentication
              *
              * https://docs.microsoft.com/en-us/azure/active-directory/develop/scenario-desktop-app-registration#redirect-uris
              */
-            string redirectURI = "https://login.microsoftonline.com/common/oauth2/nativeclient";
+            string redirectUri = s_nativeClientRedirectUri;
 
 #if NETCOREAPP
             if (parameters.AuthenticationMethod != SqlAuthenticationMethod.ActiveDirectoryDeviceCodeFlow)
             {
-                redirectURI = "http://localhost";
-            }
-#endif
-            IPublicClientApplication app;
-
-#if NETSTANDARD
-            if (parentActivityOrWindowFunc != null)
-            {
-                app = PublicClientApplicationBuilder.Create(_applicationClientId)
-                .WithAuthority(parameters.Authority)
-                .WithClientName(Common.DbConnectionStringDefaults.ApplicationName)
-                .WithClientVersion(Common.ADP.GetAssemblyVersion().ToString())
-                .WithRedirectUri(redirectURI)
-                .WithParentActivityOrWindow(parentActivityOrWindowFunc)
-                .Build();
+                redirectUri = "http://localhost";
             }
 #endif
+            PublicClientAppKey pcaKey = new PublicClientAppKey(parameters.Authority, redirectUri, _applicationClientId
 #if NETFRAMEWORK
-            if (_iWin32WindowFunc != null)
-            {
-                app = PublicClientApplicationBuilder.Create(_applicationClientId)
-                .WithAuthority(parameters.Authority)
-                .WithClientName(Common.DbConnectionStringDefaults.ApplicationName)
-                .WithClientVersion(Common.ADP.GetAssemblyVersion().ToString())
-                .WithRedirectUri(redirectURI)
-                .WithParentActivityOrWindow(_iWin32WindowFunc)
-                .Build();
-            }
+            , _iWin32WindowFunc
 #endif
-#if !NETCOREAPP
-            else
+#if NETSTANDARD
+            , _parentActivityOrWindowFunc
 #endif
-            {
-                app = PublicClientApplicationBuilder.Create(_applicationClientId)
-                .WithAuthority(parameters.Authority)
-                .WithClientName(Common.DbConnectionStringDefaults.ApplicationName)
-                .WithClientVersion(Common.ADP.GetAssemblyVersion().ToString())
-                .WithRedirectUri(redirectURI)
-                .Build();
-            }
+                );
+
+            IPublicClientApplication app = GetPublicClientAppInstance(pcaKey);
 
             if (parameters.AuthenticationMethod == SqlAuthenticationMethod.ActiveDirectoryIntegrated)
             {
@@ -185,6 +167,7 @@ public override Task<SqlAuthenticationToken> AcquireTokenAsync(SqlAuthentication
             else if (parameters.AuthenticationMethod == SqlAuthenticationMethod.ActiveDirectoryInteractive ||
                      parameters.AuthenticationMethod == SqlAuthenticationMethod.ActiveDirectoryDeviceCodeFlow)
             {
+                // Fetch available accounts from 'app' instance
                 System.Collections.Generic.IEnumerable<IAccount> accounts = await app.GetAccountsAsync();
                 IAccount account;
                 if (!string.IsNullOrEmpty(parameters.UserId))
@@ -200,17 +183,23 @@ public override Task<SqlAuthenticationToken> AcquireTokenAsync(SqlAuthentication
                 {
                     try
                     {
+                        // If 'account' is available in 'app', we use the same to acquire token silently.
+                        // Read More on API docs: https://docs.microsoft.com/dotnet/api/microsoft.identity.client.clientapplicationbase.acquiretokensilent
                         result = await app.AcquireTokenSilent(scopes, account).ExecuteAsync();
                         SqlClientEventSource.Log.TryTraceEvent("AcquireTokenAsync | Acquired access token (silent) for {0} auth mode. Expiry Time: {1}", parameters.AuthenticationMethod, result.ExpiresOn);
                     }
                     catch (MsalUiRequiredException)
                     {
+                        // An 'MsalUiRequiredException' is thrown in the case where an interaction is required with the end user of the application, 
+                        // for instance, if no refresh token was in the cache, or the user needs to consent, or re-sign-in (for instance if the password expired), 
+                        // or the user needs to perform two factor authentication.
                         result = await AcquireTokenInteractiveDeviceFlowAsync(app, scopes, parameters.ConnectionId, parameters.UserId, parameters.AuthenticationMethod);
                         SqlClientEventSource.Log.TryTraceEvent("AcquireTokenAsync | Acquired access token (interactive) for {0} auth mode. Expiry Time: {1}", parameters.AuthenticationMethod, result.ExpiresOn);
                     }
                 }
                 else
                 {
+                    // If no existing 'account' is found, we request user to sign in interactively.
                     result = await AcquireTokenInteractiveDeviceFlowAsync(app, scopes, parameters.ConnectionId, parameters.UserId, parameters.AuthenticationMethod);
                     SqlClientEventSource.Log.TryTraceEvent("AcquireTokenAsync | Acquired access token (interactive) for {0} auth mode. Expiry Time: {1}", parameters.AuthenticationMethod, result.ExpiresOn);
                 }
@@ -320,5 +309,118 @@ private class CustomWebUi : ICustomWebUi
             public Task<Uri> AcquireAuthorizationCodeAsync(Uri authorizationUri, Uri redirectUri, CancellationToken cancellationToken)
                 => _acquireAuthorizationCodeAsyncCallback.Invoke(authorizationUri, redirectUri, cancellationToken);
         }
+
+        private IPublicClientApplication GetPublicClientAppInstance(PublicClientAppKey publicClientAppKey)
+        {
+            if (!s_pcaMap.TryGetValue(publicClientAppKey, out IPublicClientApplication clientApplicationInstance))
+            {
+                clientApplicationInstance = CreateClientAppInstance(publicClientAppKey);
+                s_pcaMap.TryAdd(publicClientAppKey, clientApplicationInstance);
+            }
+            return clientApplicationInstance;
+        }
+
+        private IPublicClientApplication CreateClientAppInstance(PublicClientAppKey publicClientAppKey)
+        {
+            IPublicClientApplication publicClientApplication;
+
+#if NETSTANDARD
+            if (_parentActivityOrWindowFunc != null)
+            {
+                publicClientApplication = PublicClientApplicationBuilder.Create(publicClientAppKey._applicationClientId)
+                .WithAuthority(publicClientAppKey._authority)
+                .WithClientName(Common.DbConnectionStringDefaults.ApplicationName)
+                .WithClientVersion(Common.ADP.GetAssemblyVersion().ToString())
+                .WithRedirectUri(publicClientAppKey._redirectUri)
+                .WithParentActivityOrWindow(_parentActivityOrWindowFunc)
+                .Build();
+            }
+#endif
+#if NETFRAMEWORK
+            if (_iWin32WindowFunc != null)
+            {
+                publicClientApplication = PublicClientApplicationBuilder.Create(publicClientAppKey._applicationClientId)
+                .WithAuthority(publicClientAppKey._authority)
+                .WithClientName(Common.DbConnectionStringDefaults.ApplicationName)
+                .WithClientVersion(Common.ADP.GetAssemblyVersion().ToString())
+                .WithRedirectUri(publicClientAppKey._redirectUri)
+                .WithParentActivityOrWindow(_iWin32WindowFunc)
+                .Build();
+            }
+#endif
+#if !NETCOREAPP
+            else
+#endif
+            {
+                publicClientApplication = PublicClientApplicationBuilder.Create(publicClientAppKey._applicationClientId)
+                .WithAuthority(publicClientAppKey._authority)
+                .WithClientName(Common.DbConnectionStringDefaults.ApplicationName)
+                .WithClientVersion(Common.ADP.GetAssemblyVersion().ToString())
+                .WithRedirectUri(publicClientAppKey._redirectUri)
+                .Build();
+            }
+
+            return publicClientApplication;
+        }
+
+        internal class PublicClientAppKey
+        {
+            public readonly string _authority;
+            public readonly string _redirectUri;
+            public readonly string _applicationClientId;
+#if NETFRAMEWORK
+            public readonly Func<System.Windows.Forms.IWin32Window> _iWin32WindowFunc;
+#endif
+#if NETSTANDARD
+            public readonly Func<object> _parentActivityOrWindowFunc;
+#endif
+
+            public PublicClientAppKey(string authority, string redirectUri, string applicationClientId
+#if NETFRAMEWORK
+            , Func<System.Windows.Forms.IWin32Window> iWin32WindowFunc
+#endif
+#if NETSTANDARD
+            , Func<object> parentActivityOrWindowFunc
+#endif
+                )
+            {
+                _authority = authority;
+                _redirectUri = redirectUri;
+                _applicationClientId = applicationClientId;
+#if NETFRAMEWORK
+                _iWin32WindowFunc = iWin32WindowFunc;
+#endif
+#if NETSTANDARD
+                _parentActivityOrWindowFunc = parentActivityOrWindowFunc;
+#endif
+            }
+
+            public override bool Equals(object obj)
+            {
+                if (obj != null && obj is PublicClientAppKey pcaKey)
+                {
+                    return (string.CompareOrdinal(_authority, pcaKey._authority) == 0
+                        && string.CompareOrdinal(_redirectUri, pcaKey._redirectUri) == 0
+                        && string.CompareOrdinal(_applicationClientId, pcaKey._applicationClientId) == 0
+#if NETFRAMEWORK
+                        && pcaKey._iWin32WindowFunc == _iWin32WindowFunc
+#endif
+#if NETSTANDARD
+                        && pcaKey._parentActivityOrWindowFunc == _parentActivityOrWindowFunc
+#endif
+                    );
+                }
+                return false;
+            }
+
+            public override int GetHashCode() => Tuple.Create(_authority, _redirectUri, _applicationClientId
+#if NETFRAMEWORK
+                , _iWin32WindowFunc
+#endif
+#if NETSTANDARD
+                , _parentActivityOrWindowFunc
+#endif
+                ).GetHashCode();
+        }
     }
 }