From fd4cd15b8030942e3c51f99a86527dfa3879125c Mon Sep 17 00:00:00 2001
From: Shay Rojansky <roji@roji.org>
Date: Tue, 22 Oct 2019 11:35:14 +0200
Subject: [PATCH] Add SELECT 1 check to Exists/CanConnect checks

Fixes #18330
---
 .../Internal/SqlServerDatabaseCreator.cs      | 52 +++++++++++++++----
 1 file changed, 41 insertions(+), 11 deletions(-)

diff --git a/src/EFCore.SqlServer/Storage/Internal/SqlServerDatabaseCreator.cs b/src/EFCore.SqlServer/Storage/Internal/SqlServerDatabaseCreator.cs
index 7fdfbd28cc1..ac1efcc6322 100644
--- a/src/EFCore.SqlServer/Storage/Internal/SqlServerDatabaseCreator.cs
+++ b/src/EFCore.SqlServer/Storage/Internal/SqlServerDatabaseCreator.cs
@@ -183,13 +183,21 @@ private bool Exists(bool retryOnNotExists)
                 {
                     while (true)
                     {
+                        var opened = false;
                         try
                         {
-                            using (new TransactionScope(TransactionScopeOption.Suppress))
-                            {
-                                _connection.Open(errorsExpected: true);
-                                _connection.Close();
-                            }
+                            using var _ = new TransactionScope(TransactionScopeOption.Suppress);
+                            _connection.Open(errorsExpected: true);
+                            opened = true;
+
+                            _rawSqlCommandBuilder
+                                .Build("SELECT 1")
+                                .ExecuteNonQuery(
+                                    new RelationalCommandParameterObject(
+                                        _connection,
+                                        null,
+                                        Dependencies.CurrentContext.Context,
+                                        Dependencies.CommandLogger));
 
                             return true;
                         }
@@ -209,6 +217,13 @@ private bool Exists(bool retryOnNotExists)
 
                             Thread.Sleep(RetryDelay);
                         }
+                        finally
+                        {
+                            if (opened)
+                            {
+                                _connection.Close();
+                            }
+                        }
                     }
                 });
 
@@ -227,14 +242,22 @@ private Task<bool> ExistsAsync(bool retryOnNotExists, CancellationToken cancella
                 {
                     while (true)
                     {
+                        var opened = false;
+
                         try
                         {
-                            using (new TransactionScope(TransactionScopeOption.Suppress, TransactionScopeAsyncFlowOption.Enabled))
-                            {
-                                await _connection.OpenAsync(ct, errorsExpected: true);
-
-                                await _connection.CloseAsync();
-                            }
+                            using var _ = new TransactionScope(TransactionScopeOption.Suppress, TransactionScopeAsyncFlowOption.Enabled);
+                            await _connection.OpenAsync(ct, errorsExpected: true);
+                            opened = true;
+
+                            await _rawSqlCommandBuilder
+                                .Build("SELECT 1")
+                                .ExecuteNonQueryAsync(new RelationalCommandParameterObject(
+                                        _connection,
+                                        null,
+                                        Dependencies.CurrentContext.Context,
+                                        Dependencies.CommandLogger),
+                                    ct);
 
                             return true;
                         }
@@ -254,6 +277,13 @@ private Task<bool> ExistsAsync(bool retryOnNotExists, CancellationToken cancella
 
                             await Task.Delay(RetryDelay, ct);
                         }
+                        finally
+                        {
+                            if (opened)
+                            {
+                                await _connection.CloseAsync();
+                            }
+                        }
                     }
                 }, cancellationToken);