[Fix] Hang on infinite timeout and managed SNI (dotnet#1742)

* Fix for issue dotnet#1733 - hang on infinite timeout

Also fix SSRP when DataSource is an IP address

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SNICommon.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Net;
 using System.Net.Security;
 using System.Security.Cryptography.X509Certificates;
 
@@ -194,6 +195,15 @@ internal static bool ValidateSslServerCertificate(string targetServerName, X509C
  }
  }
 
+ internal static IPAddress[] GetDnsIpAddresses(string serverName)
+ {
+ using (TrySNIEventScope.Create(nameof(GetDnsIpAddresses)))
+ {
+ SqlClientEventSource.Log.TrySNITraceEvent(nameof(SNICommon), EventType.INFO, "Getting DNS host entries for serverName {0}.", args0: serverName);
+ return Dns.GetHostAddresses(serverName);
+ }
+ }
+
  /// <summary>
  /// Sets last error encountered for SNI
  /// </summary>

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SNITcpHandle.cs

@@ -279,14 +279,7 @@ private Socket TryConnectParallel(string hostName, int port, TimeSpan ts, bool i
  Socket availableSocket = null;
  Task<Socket> connectTask;
 
- Task<IPAddress[]> serverAddrTask = Dns.GetHostAddressesAsync(hostName);
- bool complete = serverAddrTask.Wait(ts);
-
- // DNS timed out - don't block
- if (!complete)
- return null;
-
- IPAddress[] serverAddresses = serverAddrTask.Result;
+ IPAddress[] serverAddresses = SNICommon.GetDnsIpAddresses(hostName);
 
  if (serverAddresses.Length > MaxParallelIpAddresses)
  {
@@ -338,14 +331,7 @@ private static Socket Connect(string serverName, int port, TimeSpan timeout, boo
  {
  SqlClientEventSource.Log.TrySNITraceEvent(nameof(SNITCPHandle), EventType.INFO, "IP preference : {0}", Enum.GetName(typeof(SqlConnectionIPAddressPreference), ipPreference));
 
- Task<IPAddress[]> serverAddrTask = Dns.GetHostAddressesAsync(serverName);
- bool complete = serverAddrTask.Wait(timeout);
-
- // DNS timed out - don't block
- if (!complete)
- return null;
-
- IPAddress[] ipAddresses = serverAddrTask.Result;
+ IPAddress[] ipAddresses = SNICommon.GetDnsIpAddresses(serverName);
 
  string IPv4String = null;
  string IPv6String = null;

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SSRP.cs

@@ -164,7 +164,16 @@ private static byte[] SendUDPRequest(string browserHostname, int port, byte[] re
  Debug.Assert(port >= 0 && port <= 65535, "Invalid port");
  Debug.Assert(requestPacket != null && requestPacket.Length > 0, "requestPacket should not be null or 0-length array");
 
- bool isIpAddress = IPAddress.TryParse(browserHostname, out IPAddress address);
+ if (IPAddress.TryParse(browserHostname, out IPAddress address))
+ {
+ SsrpResult response = SendUDPRequest(new IPAddress[] { address }, port, requestPacket, allIPsInParallel);
+ if (response != null && response.ResponsePacket != null)
+ return response.ResponsePacket;
+ else if (response != null && response.Error != null)
+ throw response.Error;
+ else
+ return null;
+ }
 
  TimeSpan ts = default;
  // In case the Timeout is Infinite, we will receive the max value of Int64 as the tick count
@@ -175,27 +184,7 @@ private static byte[] SendUDPRequest(string browserHostname, int port, byte[] re
  ts = ts.Ticks < 0 ? TimeSpan.FromTicks(0) : ts;
  }
 
- IPAddress[] ipAddresses = null;
- if (!isIpAddress)
- {
- Task<IPAddress[]> serverAddrTask = Dns.GetHostAddressesAsync(browserHostname);
- bool taskComplete;
- try
- {
- taskComplete = serverAddrTask.Wait(ts);
- }
- catch (AggregateException ae)
- {
- throw ae.InnerException;
- }
-
- // If DNS took too long, need to return instead of blocking
- if (!taskComplete)
- return null;
-
- ipAddresses = serverAddrTask.Result;
- }
-
+ IPAddress[] ipAddresses = SNICommon.GetDnsIpAddresses(browserHostname);
  Debug.Assert(ipAddresses.Length > 0, "DNS should throw if zero addresses resolve");
 
  switch (ipPreference)
@@ -272,7 +261,7 @@ private static SsrpResult SendUDPRequest(IPAddress[] ipAddresses, int port, byte
  for (int i = 0; i < ipAddresses.Length; i++)
  {
  IPEndPoint endPoint = new IPEndPoint(ipAddresses[i], port);
- tasks.Add(Task.Factory.StartNew<SsrpResult>(() => SendUDPRequest(endPoint, requestPacket)));
+ tasks.Add(Task.Factory.StartNew<SsrpResult>(() => SendUDPRequest(endPoint, requestPacket), cts.Token));
  }
 
  List<Task<SsrpResult>> completedTasks = new();

src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/ConnectivityTests/ConnectivityTest.cs

@@ -85,6 +85,21 @@ public static void EnvironmentHostNameSPIDTest()
  Assert.True(false, "No non-empty hostname found for the application");
  }
 
+ [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup))]
+ public static async void ConnectionTimeoutInfiniteTest()
+ {
+ // Exercise the special-case infinite connect timeout code path
+ SqlConnectionStringBuilder builder = new(DataTestUtility.TCPConnectionString)
+ {
+ ConnectTimeout = 0 // Infinite
+ };
+
+ using SqlConnection conn = new(builder.ConnectionString);
+ CancellationTokenSource cts = new(30000);
+ // Will throw TaskCanceledException and fail the test in the event of a hang
+ await conn.OpenAsync(cts.Token);
+ }
+
  [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup))]
  public static void ConnectionTimeoutTestWithThread()
  {

src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/InstanceNameTest/InstanceNameTest.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Net;
 using System.Net.Sockets;
 using System.Text;
 using System.Threading.Tasks;
@@ -12,17 +13,17 @@ namespace Microsoft.Data.SqlClient.ManualTesting.Tests
 {
  public static class InstanceNameTest
  {
- [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup))]
+ [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.IsNotAzureServer), nameof(DataTestUtility.IsNotAzureSynapse), nameof(DataTestUtility.AreConnStringsSetup))]
  public static void ConnectToSQLWithInstanceNameTest()
  {
  SqlConnectionStringBuilder builder = new(DataTestUtility.TCPConnectionString);
 
  bool proceed = true;
  string dataSourceStr = builder.DataSource.Replace("tcp:", "");
  string[] serverNamePartsByBackSlash = dataSourceStr.Split('\\');
+ string hostname = serverNamePartsByBackSlash[0];
  if (!dataSourceStr.Contains(",") && serverNamePartsByBackSlash.Length == 2)
  {
- string hostname = serverNamePartsByBackSlash[0];
  proceed = !string.IsNullOrWhiteSpace(hostname) && IsBrowserAlive(hostname);
  }
 
@@ -31,6 +32,17 @@ public static void ConnectToSQLWithInstanceNameTest()
  using SqlConnection connection = new(builder.ConnectionString);
  connection.Open();
  connection.Close();
+
+ if (builder.Encrypt != SqlConnectionEncryptOption.Strict)
+ {
+ // Exercise the IP address-specific code in SSRP
+ IPAddress[] addresses = Dns.GetHostAddresses(hostname);
+ builder.DataSource = builder.DataSource.Replace(hostname, addresses[0].ToString());
+ builder.TrustServerCertificate = true;
+ using SqlConnection connection2 = new(builder.ConnectionString);
+ connection2.Open();
+ connection2.Close();
+ }
  }
  }