Parallelize SSRP requests when MSF is specified (#1578)

Author: David-Engel

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

@@ -108,6 +108,7 @@ internal class SNICommon
         internal const int ConnTimeoutError = 11;
         internal const int ConnNotUsableError = 19;
         internal const int InvalidConnStringError = 25;
+        internal const int ErrorLocatingServerInstance = 26;
         internal const int HandshakeFailureError = 31;
         internal const int InternalExceptionError = 35;
         internal const int ConnOpenFailedError = 40;

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

@@ -141,7 +141,7 @@ private static bool IsErrorStatus(SecurityStatusPalErrorCode errorCode)
         /// <param name="isIntegratedSecurity"></param>
         /// <param name="ipPreference">IP address preference</param>
         /// <param name="cachedFQDN">Used for DNS Cache</param>
-        /// <param name="pendingDNSInfo">Used for DNS Cache</param>       
+        /// <param name="pendingDNSInfo">Used for DNS Cache</param>
         /// <returns>SNI handle</returns>
         internal static SNIHandle CreateConnectionHandle(string fullServerName, bool ignoreSniOpenTimeout, long timerExpire, out byte[] instanceName, ref byte[][] spnBuffer,
                                         bool flushCache, bool async, bool parallel, bool isIntegratedSecurity, SqlConnectionIPAddressPreference ipPreference, string cachedFQDN, ref SQLDNSInfo pendingDNSInfo)
@@ -263,7 +263,7 @@ private static byte[][] GetSqlServerSPNs(string hostNameOrAddress, string portOr
         /// <param name="parallel">Should MultiSubnetFailover be used</param>
         /// <param name="ipPreference">IP address preference</param>
         /// <param name="cachedFQDN">Key for DNS Cache</param>
-        /// <param name="pendingDNSInfo">Used for DNS Cache</param>        
+        /// <param name="pendingDNSInfo">Used for DNS Cache</param>
         /// <returns>SNITCPHandle</returns>
         private static SNITCPHandle CreateTcpHandle(DataSource details, long timerExpire, bool parallel, SqlConnectionIPAddressPreference ipPreference, string cachedFQDN, ref SQLDNSInfo pendingDNSInfo)
         {
@@ -285,12 +285,12 @@ private static SNITCPHandle CreateTcpHandle(DataSource details, long timerExpire
                 try
                 {
                     port = isAdminConnection ?
-                            SSRP.GetDacPortByInstanceName(hostName, details.InstanceName) :
-                            SSRP.GetPortByInstanceName(hostName, details.InstanceName);
+                            SSRP.GetDacPortByInstanceName(hostName, details.InstanceName, timerExpire, parallel, ipPreference) :
+                            SSRP.GetPortByInstanceName(hostName, details.InstanceName, timerExpire, parallel, ipPreference);
                 }
                 catch (SocketException se)
                 {
-                    SNILoadHandle.SingletonInstance.LastError = new SNIError(SNIProviders.TCP_PROV, SNICommon.InvalidConnStringError, se);
+                    SNILoadHandle.SingletonInstance.LastError = new SNIError(SNIProviders.TCP_PROV, SNICommon.ErrorLocatingServerInstance, se);
                     return null;
                 }
             }

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

@@ -146,9 +146,9 @@ public SNITCPHandle(string serverName, int port, long timerExpire, bool parallel
                     bool reportError = true;
 
                     SqlClientEventSource.Log.TrySNITraceEvent(nameof(SNITCPHandle), EventType.INFO, "Connection Id {0}, Connecting to serverName {1} and port {2}", args0: _connectionId, args1: serverName, args2: port);
-                    // We will always first try to connect with serverName as before and let the DNS server to resolve the serverName.
-                    // If the DSN resolution fails, we will try with IPs in the DNS cache if existed. We try with cached IPs based on IPAddressPreference.
-                    // The exceptions will be throw to upper level and be handled as before.
+                    // We will always first try to connect with serverName as before and let DNS resolve the serverName.
+                    // If DNS resolution fails, we will try with IPs in the DNS cache if they exist. We try with cached IPs based on IPAddressPreference.
+                    // Exceptions will be thrown to the caller and be handled as before.
                     try
                     {
                         if (parallel)
@@ -280,7 +280,12 @@ private Socket TryConnectParallel(string hostName, int port, TimeSpan ts, bool i
             Task<Socket> connectTask;
 
             Task<IPAddress[]> serverAddrTask = Dns.GetHostAddressesAsync(hostName);
-            serverAddrTask.Wait(ts);
+            bool complete = serverAddrTask.Wait(ts);
+
+            // DNS timed out - don't block
+            if (!complete)
+                return null;
+
             IPAddress[] serverAddresses = serverAddrTask.Result;
 
             if (serverAddresses.Length > MaxParallelIpAddresses)
@@ -324,7 +329,6 @@ private Socket TryConnectParallel(string hostName, int port, TimeSpan ts, bool i
 
             availableSocket = connectTask.Result;
             return availableSocket;
-
         }
 
         // Connect to server with hostName and port.
@@ -334,7 +338,14 @@ 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));
 
-            IPAddress[] ipAddresses = Dns.GetHostAddresses(serverName);
+            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;
 
             string IPv4String = null;
             string IPv6String = null;