Use string for SNI instead of byte[]

src/Microsoft.Data.SqlClient/netcore/src/Microsoft.Data.SqlClient.csproj

@@ -515,6 +515,9 @@
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\SqlObjectPool.cs">
       <Link>Microsoft\Data\SqlClient\SqlObjectPool.cs</Link>
     </Compile>
+    <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\SqlObjectPools.cs">
+      <Link>Microsoft\Data\SqlClient\SqlObjectPools.cs</Link>
+    </Compile>
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\SqlParameter.cs">
       <Link>Microsoft\Data\SqlClient\SqlParameter.cs</Link>
     </Compile>

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

@@ -4,6 +4,7 @@
 
 using System;
 using System.Buffers;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
 using System.Net;
@@ -33,7 +34,7 @@ internal class SNIProxy
         /// <param name="fullServerName">Full server name from connection string</param>
         /// <param name="timeout">Timer expiration</param>
         /// <param name="instanceName">Instance name</param>
-        /// <param name="spnBuffer">SPN</param>
+        /// <param name="spns">SPNs</param>
         /// <param name="serverSPN">pre-defined SPN</param>
         /// <param name="flushCache">Flush packet cache</param>
         /// <param name="async">Asynchronous connection</param>
@@ -50,7 +51,7 @@ internal static SNIHandle CreateConnectionHandle(
             string fullServerName,
             TimeoutTimer timeout,
             out byte[] instanceName,
-            ref byte[][] spnBuffer,
+            ref string[] spns,
             string serverSPN,
             bool flushCache,
             bool async,
@@ -102,7 +103,7 @@ internal static SNIHandle CreateConnectionHandle(
             {
                 try
                 {
-                    spnBuffer = GetSqlServerSPNs(details, serverSPN);
+                    spns = GetSqlServerSPNs(details, serverSPN);
                 }
                 catch (Exception e)
                 {
@@ -114,12 +115,12 @@ internal static SNIHandle CreateConnectionHandle(
             return sniHandle;
         }
 
-        private static byte[][] GetSqlServerSPNs(DataSource dataSource, string serverSPN)
+        private static string[] GetSqlServerSPNs(DataSource dataSource, string serverSPN)
         {
             Debug.Assert(!string.IsNullOrWhiteSpace(dataSource.ServerName));
             if (!string.IsNullOrWhiteSpace(serverSPN))
             {
-                return new byte[1][] { Encoding.Unicode.GetBytes(serverSPN) };
+                return new[] { serverSPN };
             }
 
             string hostName = dataSource.ServerName;
@@ -137,7 +138,7 @@ private static byte[][] GetSqlServerSPNs(DataSource dataSource, string serverSPN
             return GetSqlServerSPNs(hostName, postfix, dataSource.ResolvedProtocol);
         }
 
-        private static byte[][] GetSqlServerSPNs(string hostNameOrAddress, string portOrInstanceName, DataSource.Protocol protocol)
+        private static string[] GetSqlServerSPNs(string hostNameOrAddress, string portOrInstanceName, DataSource.Protocol protocol)
         {
             Debug.Assert(!string.IsNullOrWhiteSpace(hostNameOrAddress));
             IPHostEntry hostEntry = null;
@@ -168,12 +169,12 @@ private static byte[][] GetSqlServerSPNs(string hostNameOrAddress, string portOr
                 string serverSpnWithDefaultPort = serverSpn + $":{DefaultSqlServerPort}";
                 // Set both SPNs with and without Port as Port is optional for default instance
                 SqlClientEventSource.Log.TryAdvancedTraceEvent("SNIProxy.GetSqlServerSPN | Info | ServerSPNs {0} and {1}", serverSpn, serverSpnWithDefaultPort);
-                return new byte[][] { Encoding.Unicode.GetBytes(serverSpn), Encoding.Unicode.GetBytes(serverSpnWithDefaultPort) };
+                return new[] { serverSpn, serverSpnWithDefaultPort };
             }
             // else Named Pipes do not need to valid port
 
             SqlClientEventSource.Log.TryAdvancedTraceEvent("SNIProxy.GetSqlServerSPN | Info | ServerSPN {0}", serverSpn);
-            return new byte[][] { Encoding.Unicode.GetBytes(serverSpn) };
+            return new[] { serverSpn };
         }
 
         /// <summary>

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParser.cs

@@ -112,8 +112,7 @@ internal sealed partial class TdsParser
 
         private bool _is2022 = false;
 
-        private byte[][] _sniSpnBuffer = null;
-        // UNDONE - need to have some for both instances - both command and default???
+        private string[] _serverSpn = null;
 
         // SqlStatistics
         private SqlStatistics _statistics = null;
@@ -390,7 +389,7 @@ internal void Connect(
             }
             else
             {
-                _sniSpnBuffer = null;
+                _serverSpn = null;
                 SqlClientEventSource.Log.TryTraceEvent("TdsParser.Connect | SEC | Connection Object Id {0}, Authentication Mode: {1}", _connHandler.ObjectID,
                     authType == SqlAuthenticationMethod.NotSpecified ? SqlAuthenticationMethod.SqlPassword.ToString() : authType.ToString());
             }
@@ -402,7 +401,7 @@ internal void Connect(
                 SqlClientEventSource.Log.TryTraceEvent("<sc.TdsParser.Connect|SEC> Encryption will be disabled as target server is a SQL Local DB instance.");
             }
 
-            _sniSpnBuffer = null;
+            _serverSpn = null;
             _authenticationProvider = null;
 
             // AD Integrated behaves like Windows integrated when connecting to a non-fedAuth server
@@ -441,7 +440,7 @@ internal void Connect(
                 serverInfo.ExtendedServerName,
                 timeout,
                 out instanceName,
-                ref _sniSpnBuffer,
+                ref _serverSpn,
                 false,
                 true,
                 fParallel,
@@ -540,7 +539,7 @@ internal void Connect(
                 _physicalStateObj.CreatePhysicalSNIHandle(
                     serverInfo.ExtendedServerName,
                     timeout, out instanceName,
-                    ref _sniSpnBuffer,
+                    ref _serverSpn,
                     true,
                     true,
                     fParallel,
@@ -13317,7 +13316,7 @@ internal string TraceString()
                            _fMARS ? bool.TrueString : bool.FalseString,
                            _sessionPool == null ? "(null)" : _sessionPool.TraceString(),
                            _is2005 ? bool.TrueString : bool.FalseString,
-                           _sniSpnBuffer == null ? "(null)" : _sniSpnBuffer.Length.ToString((IFormatProvider)null),
+                           _serverSpn == null ? "(null)" : _serverSpn.Length.ToString((IFormatProvider)null),
                            _physicalStateObj != null ? "(null)" : _physicalStateObj.ErrorCount.ToString((IFormatProvider)null),
                            _physicalStateObj != null ? "(null)" : _physicalStateObj.WarningCount.ToString((IFormatProvider)null),
                            _physicalStateObj != null ? "(null)" : _physicalStateObj.PreAttentionErrorCount.ToString((IFormatProvider)null),

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParserStateObject.netcore.cs

@@ -186,7 +186,7 @@ internal abstract void CreatePhysicalSNIHandle(
             string serverName,
             TimeoutTimer timeout,
             out byte[] instanceName,
-            ref byte[][] spnBuffer,
+            ref string[] spns,
             bool flushCache,
             bool async,
             bool fParallel,

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParserStateObjectManaged.cs

@@ -81,7 +81,7 @@ internal override void CreatePhysicalSNIHandle(
             string serverName,
             TimeoutTimer timeout,
             out byte[] instanceName,
-            ref byte[][] spnBuffer,
+            ref string[] spns,
             bool flushCache,
             bool async,
             bool parallel,
@@ -94,7 +94,7 @@ internal override void CreatePhysicalSNIHandle(
             string hostNameInCertificate,
             string serverCertificateFilename)
         {
-            SNIHandle? sessionHandle = SNIProxy.CreateConnectionHandle(serverName, timeout, out instanceName, ref spnBuffer, serverSPN,
+            SNIHandle? sessionHandle = SNIProxy.CreateConnectionHandle(serverName, timeout, out instanceName, ref spns, serverSPN,
                 flushCache, async, parallel, isIntegratedSecurity, iPAddressPreference, cachedFQDN, ref pendingDNSInfo, tlsFirst,
                 hostNameInCertificate, serverCertificateFilename);
 

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParserStateObjectNative.cs

@@ -144,7 +144,7 @@ internal override void CreatePhysicalSNIHandle(
             string serverName,
             TimeoutTimer timeout,
             out byte[] instanceName,
-            ref byte[][] spnBuffer,
+            ref string[] spns,
             bool flushCache,
             bool async,
             bool fParallel,
@@ -157,31 +157,28 @@ internal override void CreatePhysicalSNIHandle(
             string hostNameInCertificate,
             string serverCertificateFilename)
         {
-            // We assume that the loadSSPILibrary has been called already. now allocate proper length of buffer
-            spnBuffer = new byte[1][];
             if (isIntegratedSecurity)
             {
                 // now allocate proper length of buffer
                 if (!string.IsNullOrEmpty(serverSPN))
                 {
                     // Native SNI requires the Unicode encoding and any other encoding like UTF8 breaks the code.
-                    byte[] srvSPN = Encoding.Unicode.GetBytes(serverSPN);
-                    Trace.Assert(srvSPN.Length <= SniNativeWrapper.SniMaxComposedSpnLength, "Length of the provided SPN exceeded the buffer size.");
-                    spnBuffer[0] = srvSPN;
                     SqlClientEventSource.Log.TryTraceEvent("<{0}.{1}|SEC> Server SPN `{2}` from the connection string is used.", nameof(TdsParserStateObjectNative), nameof(CreatePhysicalSNIHandle), serverSPN);
                 }
                 else
                 {
-                    spnBuffer[0] = new byte[SniNativeWrapper.SniMaxComposedSpnLength];
+                    // This will signal to the interop layer that we need to retrieve the SPN
+                    serverSPN = string.Empty;
                 }
             }
 
             ConsumerInfo myInfo = CreateConsumerInfo(async);
             SQLDNSInfo cachedDNSInfo;
             bool ret = SQLFallbackDNSCache.Instance.GetDNSInfo(cachedFQDN, out cachedDNSInfo);
 
-            _sessionHandle = new SNIHandle(myInfo, serverName, spnBuffer[0], timeout.MillisecondsRemainingInt, out instanceName,
+            _sessionHandle = new SNIHandle(myInfo, serverName, ref serverSPN, timeout.MillisecondsRemainingInt, out instanceName,
                 flushCache, !async, fParallel, ipPreference, cachedDNSInfo, hostNameInCertificate);
+            spns = new[] { serverSPN.TrimEnd() };
         }
 
         protected override uint SNIPacketGetData(PacketHandle packet, byte[] _inBuff, ref uint dataSize)

src/Microsoft.Data.SqlClient/netfx/src/Microsoft.Data.SqlClient.csproj

@@ -337,10 +337,13 @@
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\Sql\SqlDataSourceEnumerator.cs">
       <Link>Microsoft\Data\Sql\SqlDataSourceEnumerator.cs</Link>
     </Compile>
-	<Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\SqlObjectPool.cs">
-	  <Link>Microsoft\Data\SqlClient\SqlObjectPool.cs</Link>
-	</Compile>
-	<Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\AAsyncCallContext.cs">
+    <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\SqlObjectPool.cs">
+      <Link>Microsoft\Data\SqlClient\SqlObjectPool.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\SqlObjectPools.cs">
+      <Link>Microsoft\Data\SqlClient\SqlObjectPools.cs</Link>
+    </Compile>
+	  <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\AAsyncCallContext.cs">
       <Link>Microsoft\Data\SqlClient\AAsyncCallContext.cs</Link>
     </Compile>
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\ActiveDirectoryAuthenticationTimeoutRetryHelper.cs">
@@ -854,6 +857,7 @@
     <Compile Include="Microsoft\Data\Common\DbConnectionString.cs" />
     <Compile Include="Microsoft\Data\Common\GreenMethods.cs" />
     <Compile Include="Microsoft\Data\SqlClient\assemblycache.cs" />
+    <Compile Include="Microsoft\Data\SqlClient\BufferWriterExtensions.cs" />
     <Compile Include="Microsoft\Data\SqlClient\Reliability\SqlConfigurableRetryLogicManager.LoadType.cs" />
     <Compile Include="Microsoft\Data\SqlClient\Server\SmiConnection.cs" />
     <Compile Include="Microsoft\Data\SqlClient\Server\SmiContext.cs" />

src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/BufferWriterExtensions.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Buffers;
+using System.Text;
+
+namespace Microsoft.Data.SqlClient
+{
+    internal static class BufferWriterExtensions
+    {
+        internal static long GetBytes(this Encoding encoding, string str, IBufferWriter<byte> bufferWriter)
+        {
+            var count = encoding.GetByteCount(str);
+            var array = ArrayPool<byte>.Shared.Rent(count);
+
+            try
+            {
+                var length = encoding.GetBytes(str, 0, str.Length, array, 0);
+                bufferWriter.Write(array.AsSpan(0, length));
+                return length;
+            }
+            finally
+            {
+                ArrayPool<byte>.Shared.Return(array);
+            }
+        }
+    }
+}