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Feature | Add enhanced routing env change support. #3970

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9dc2257
Add enhanced routing env change support.
mdaigle Feb 19, 2026
518de05
Update comments.
mdaigle Feb 20, 2026
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2 changes: 1 addition & 1 deletion src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/Connection/ServerInfo.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,7 @@ internal ServerInfo(
PreRoutingServerName = preRoutingServerName;
UserProtocol = TdsEnums.TCP;
SetDerivedNames(UserProtocol, UserServerName);
ResolvedDatabaseName = userOptions.InitialCatalog;
ResolvedDatabaseName = routing?.DatabaseName ?? userOptions.InitialCatalog;
ServerSPN = serverSpn;
}

Expand Down
70 changes: 38 additions & 32 deletions ...Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/Connection/SqlConnectionInternal.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -223,7 +223,7 @@ internal class SqlConnectionInternal : DbConnectionInternal, IDisposable

private string _currentLanguage;

private int _currentPacketSize;


/// <summary>
/// Pool this connection is associated with, if any.
Expand Down Expand Up @@ -262,7 +262,7 @@ internal class SqlConnectionInternal : DbConnectionInternal, IDisposable
/// </summary>
private DbConnectionPoolAuthenticationContext _newDbConnectionPoolAuthenticationContext;

private Guid _originalClientConnectionId = Guid.Empty;


private string _originalDatabase;

Expand All @@ -280,7 +280,7 @@ internal class SqlConnectionInternal : DbConnectionInternal, IDisposable
// @TODO: Rename to match naming conventions (remove f prefix)
private readonly bool _fResetConnection;

private string _routingDestination = null;


// @TODO: Rename to match naming conventions
private bool _SQLDNSRetryEnabled = false;
Expand Down Expand Up @@ -669,17 +669,9 @@ internal override bool IsTransactionRoot
get => DelegatedTransaction?.IsActive == true;
}

// @TODO: Make auto-property
internal Guid OriginalClientConnectionId
{
get => _originalClientConnectionId;
}
internal Guid OriginalClientConnectionId { get; private set; } = Guid.Empty;

// @TODO: Make auto-property
internal int PacketSize
{
get => _currentPacketSize;
}
internal int PacketSize { get; private set; }

// @TODO: Make auto-property
internal TdsParser Parser
Expand All @@ -706,11 +698,7 @@ internal SqlConnectionPoolGroupProviderInfo PoolGroupProviderInfo
/// </summary>
internal byte[] PromotedDtcToken { get; private set; }

// @TODO: Make auto-property
internal string RoutingDestination
{
get => _routingDestination;
}
internal string RoutingDestination { get; private set; }

internal RoutingInfo RoutingInfo { get; private set; } = null;

Expand Down Expand Up @@ -1187,7 +1175,7 @@ internal void OnEnvChange(SqlEnvChange rec)
break;

case TdsEnums.ENV_PACKETSIZE:
_currentPacketSize = int.Parse(rec._newValue, CultureInfo.InvariantCulture);
PacketSize = int.Parse(rec._newValue, CultureInfo.InvariantCulture);
break;

case TdsEnums.ENV_COLLATION:
Expand Down Expand Up @@ -1267,6 +1255,23 @@ internal void OnEnvChange(SqlEnvChange rec)
RoutingInfo = rec._newRoutingInfo;
break;

case TdsEnums.ENV_ENHANCEDROUTING:
SqlClientEventSource.Log.TryAdvancedTraceEvent(
$"SqlInternalConnectionTds.OnEnvChange | ADV | " +
$"Object ID {ObjectID}, " +
$"Received enhanced routing info");

if (string.IsNullOrEmpty(rec._newRoutingInfo.ServerName) ||
string.IsNullOrEmpty(rec._newRoutingInfo.DatabaseName) ||
rec._newRoutingInfo.Protocol != 0 ||
rec._newRoutingInfo.Port == 0)
{
throw SQL.ROR_InvalidEnhancedRoutingInfo(this);
}

RoutingInfo = rec._newRoutingInfo;
break;

default:
Debug.Fail("Missed token in EnvChange!");
break;
Expand Down Expand Up @@ -1733,11 +1738,6 @@ internal void OnFeatureExtAck(int featureId, byte[] data)
}
case TdsEnums.FEATUREEXT_ENHANCEDROUTINGSUPPORT:
{
SqlClientEventSource.Log.TryAdvancedTraceEvent(
$"SqlInternalConnectionTds.OnFeatureExtAck | ADV | " +
$"Object ID {ObjectID}, " +
$"Received feature extension acknowledgement for ENHANCEDROUTINGSUPPORT");

if (data.Length != 1)
{
SqlClientEventSource.Log.TryTraceEvent(
Expand All @@ -1750,6 +1750,12 @@ internal void OnFeatureExtAck(int featureId, byte[] data)

// A value of 1 indicates that the server supports the feature.
IsEnhancedRoutingSupportEnabled = data[0] == 1;

SqlClientEventSource.Log.TryAdvancedTraceEvent(
$"SqlInternalConnectionTds.OnFeatureExtAck | ADV | " +
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@mdaigle mdaigle Feb 20, 2026

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Following the format of other trace messages in this file. As a separate piece of work, the messages should be edited up to better match the file name.

$"Object ID {ObjectID}, " +
$"Received feature extension acknowledgement for " +
$"ENHANCEDROUTINGSUPPORT = {IsEnhancedRoutingSupportEnabled}");
break;
}
case TdsEnums.FEATUREEXT_USERAGENT:
Expand Down Expand Up @@ -2967,7 +2973,7 @@ private void Login(
// Gather all the settings the user set in the connection string or properties and do
// the login
CurrentDatabase = server.ResolvedDatabaseName;
_currentPacketSize = ConnectionOptions.PacketSize;
PacketSize = ConnectionOptions.PacketSize;
_currentLanguage = ConnectionOptions.CurrentLanguage;

int timeoutInSeconds = 0;
Expand Down Expand Up @@ -3018,7 +3024,7 @@ private void Login(
// Treat AD Integrated like Windows integrated when against a non-FedAuth endpoint
login.useSSPI = ConnectionOptions.IntegratedSecurity || (ConnectionOptions.Authentication == SqlAuthenticationMethod.ActiveDirectoryIntegrated && !_fedAuthRequired);

login.packetSize = _currentPacketSize;
login.packetSize = PacketSize;
login.newPassword = newPassword;
login.readOnlyIntent = ConnectionOptions.ApplicationIntent == ApplicationIntent.ReadOnly;
login.credential = _credential;
Expand Down Expand Up @@ -3302,11 +3308,11 @@ private void LoginNoFailover(
serverInfo.ResolvedServerName,
serverInfo.ServerSPN);
_timeoutErrorInternal.SetInternalSourceType(SqlConnectionInternalSourceType.RoutingDestination);
_originalClientConnectionId = _clientConnectionId;
_routingDestination = serverInfo.UserServerName;
OriginalClientConnectionId = _clientConnectionId;
RoutingDestination = serverInfo.UserServerName;

// Restore properties that could be changed by the environment tokens
_currentPacketSize = ConnectionOptions.PacketSize;
PacketSize = ConnectionOptions.PacketSize;
_currentLanguage = _originalLanguage = ConnectionOptions.CurrentLanguage;
CurrentDatabase = _originalDatabase = ConnectionOptions.InitialCatalog;
ServerProvidedFailoverPartner = null;
Expand Down Expand Up @@ -3605,11 +3611,11 @@ private void LoginWithFailover(
currentServerInfo.ResolvedServerName,
currentServerInfo.ServerSPN);
_timeoutErrorInternal.SetInternalSourceType(SqlConnectionInternalSourceType.RoutingDestination);
_originalClientConnectionId = _clientConnectionId;
_routingDestination = currentServerInfo.UserServerName;
OriginalClientConnectionId = _clientConnectionId;
RoutingDestination = currentServerInfo.UserServerName;

// Restore properties that could be changed by the environment tokens
_currentPacketSize = connectionOptions.PacketSize;
PacketSize = connectionOptions.PacketSize;
_currentLanguage = _originalLanguage = ConnectionOptions.CurrentLanguage;
CurrentDatabase = _originalDatabase = connectionOptions.InitialCatalog;
ServerProvidedFailoverPartner = null;
Expand Down
9 changes: 9 additions & 0 deletions src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlUtil.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1188,6 +1188,15 @@ internal static Exception ROR_InvalidRoutingInfo(SqlConnectionInternal internalC
return exc;
}

internal static Exception ROR_InvalidEnhancedRoutingInfo(SqlConnectionInternal internalConnection)
{
SqlErrorCollection errors = new SqlErrorCollection();
errors.Add(new SqlError(0, (byte)0x00, TdsEnums.FATAL_ERROR_CLASS, null, (StringsHelper.GetString(Strings.SQLROR_InvalidEnhancedRoutingInfo)), "", 0));
SqlException exc = SqlException.CreateException(errors, null, internalConnection, innerException: null, batchCommand: null);
exc._doNotReconnect = true;
return exc;
}

internal static Exception ROR_TimeoutAfterRoutingInfo(SqlConnectionInternal internalConnection)
{
SqlErrorCollection errors = new SqlErrorCollection();
Expand Down
24 changes: 1 addition & 23 deletions src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsEnums.cs
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Expand Up @@ -186,29 +186,7 @@ internal static class TdsEnums
public const byte ENV_SPRESETCONNECTIONACK = 18; // SP_Reset_Connection ack
public const byte ENV_USERINSTANCE = 19; // User Instance
public const byte ENV_ROUTING = 20; // Routing (ROR) information

public enum EnvChangeType : byte
{
ENVCHANGE_DATABASE = ENV_DATABASE,
ENVCHANGE_LANG = ENV_LANG,
ENVCHANGE_CHARSET = ENV_CHARSET,
ENVCHANGE_PACKETSIZE = ENV_PACKETSIZE,
ENVCHANGE_LOCALEID = ENV_LOCALEID,
ENVCHANGE_COMPFLAGS = ENV_COMPFLAGS,
ENVCHANGE_COLLATION = ENV_COLLATION,
ENVCHANGE_BEGINTRAN = ENV_BEGINTRAN,
ENVCHANGE_COMMITTRAN = ENV_COMMITTRAN,
ENVCHANGE_ROLLBACKTRAN = ENV_ROLLBACKTRAN,
ENVCHANGE_ENLISTDTC = ENV_ENLISTDTC,
ENVCHANGE_DEFECTDTC = ENV_DEFECTDTC,
ENVCHANGE_LOGSHIPNODE = ENV_LOGSHIPNODE,
ENVCHANGE_PROMOTETRANSACTION = ENV_PROMOTETRANSACTION,
ENVCHANGE_TRANSACTIONMANAGERADDRESS = ENV_TRANSACTIONMANAGERADDRESS,
ENVCHANGE_TRANSACTIONENDED = ENV_TRANSACTIONENDED,
ENVCHANGE_SPRESETCONNECTIONACK = ENV_SPRESETCONNECTIONACK,
ENVCHANGE_USERINSTANCE = ENV_USERINSTANCE,
ENVCHANGE_ROUTING = ENV_ROUTING
}
public const byte ENV_ENHANCEDROUTING = 21; // Enhanced Routing (ROR) information

// done status stream bit masks
public const int DONE_MORE = 0x0001; // more command results coming
Expand Down
106 changes: 105 additions & 1 deletion src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs
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Expand Up @@ -3385,6 +3385,7 @@ private TdsOperationStatus TryProcessEnvChange(int tokenLength, TdsParserStateOb
break;

case TdsEnums.ENV_ROUTING:
{
ushort newLength;
result = stateObj.TryReadUInt16(out newLength);
if (result != TdsOperationStatus.Done)
Expand Down Expand Up @@ -3428,8 +3429,22 @@ private TdsOperationStatus TryProcessEnvChange(int tokenLength, TdsParserStateOb
{
return result;
}
env._length = env._newLength + oldLength + 5; // 5=2*sizeof(UInt16)+sizeof(byte) [token+newLength+oldLength]
// Set the total length of the token
// total = headers + size of new value + size of old value
// headers = token id+newLengthHeader+oldLengthHeader = sizeof(byte) + 2*sizeof(UInt16) = 5
env._length = env._newLength + oldLength + 5;
break;
}

case TdsEnums.ENV_ENHANCEDROUTING:
{
result = TryProcessEnhancedRoutingToken(env, stateObj);
if (result != TdsOperationStatus.Done)
{
return result;
}
break;
}

default:
Debug.Fail("Unknown environment change token: " + env._type);
Expand All @@ -3442,6 +3457,95 @@ private TdsOperationStatus TryProcessEnvChange(int tokenLength, TdsParserStateOb
return TdsOperationStatus.Done;
}

/// <summary>
/// Processes an enhanced routing ENVCHANGE token from the TDS stream.
/// This token contains the routing information for the connection, including the protocol,
/// port, server name, and database name. The enhanced routing token has the following structure:
/// <list type="bullet">
/// <item>NewValueLength (USHORT) - length of the new value</item>
/// <item>Protocol (BYTE) - routing protocol (must be 0 = TCP)</item>
/// <item>Port (USHORT) - routing port number</item>
/// <item>AlternateServerNameLength (USHORT) - length of the alternate server name in characters</item>
/// <item>AlternateServerName (UNICODE_STRING) - the server name to route to</item>
/// <item>AlternateDatabaseNameLength (USHORT) - length of the alternate database name in characters</item>
/// <item>AlternateDatabaseName (UNICODE_STRING) - the database name to route to</item>
/// <item>OldValueLength (USHORT) - length of the old value</item>
/// <item>OldValue (BYTE[]) - old value (skipped)</item>
/// </list>
/// </summary>
private TdsOperationStatus TryProcessEnhancedRoutingToken(SqlEnvChange env, TdsParserStateObject stateObj)
{
ushort newLength;
TdsOperationStatus result = stateObj.TryReadUInt16(out newLength);
if (result != TdsOperationStatus.Done)
{
return result;
}
env._newLength = newLength;

byte protocol;
result = stateObj.TryReadByte(out protocol);
if (result != TdsOperationStatus.Done)
{
return result;
}

ushort port;
result = stateObj.TryReadUInt16(out port);
if (result != TdsOperationStatus.Done)
{
return result;
}

ushort serverLen;
result = stateObj.TryReadUInt16(out serverLen);
if (result != TdsOperationStatus.Done)
{
return result;
}

string serverName;
result = stateObj.TryReadString(serverLen, out serverName);
if (result != TdsOperationStatus.Done)
{
return result;
}

ushort databaseLen;
result = stateObj.TryReadUInt16(out databaseLen);
if (result != TdsOperationStatus.Done)
{
return result;
}

string databaseName;
result = stateObj.TryReadString(databaseLen, out databaseName);
if (result != TdsOperationStatus.Done)
{
return result;
}

env._newRoutingInfo = new RoutingInfo(protocol, port, serverName, databaseName);

ushort oldLength;
result = stateObj.TryReadUInt16(out oldLength);
if (result != TdsOperationStatus.Done)
{
return result;
}

result = stateObj.TrySkipBytes(oldLength);
if (result != TdsOperationStatus.Done)
{
return result;
}

// 5 = 2*sizeof(UInt16)+sizeof(byte) [token+newLength+oldLength]
env._length = env._newLength + oldLength + 5;

return TdsOperationStatus.Done;
}

private TdsOperationStatus TryReadTwoBinaryFields(SqlEnvChange env, TdsParserStateObject stateObj)
{
// Used by ProcessEnvChangeToken
Expand Down
11 changes: 9 additions & 2 deletions src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParserHelperClasses.cs
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Expand Up @@ -89,11 +89,18 @@ internal class RoutingInfo
internal ushort Port { get; private set; }
internal string ServerName { get; private set; }

internal RoutingInfo(byte protocol, ushort port, string servername)
/// <summary>
/// The DatabaseName property is only used when routing via an EnhancedRouting ENVCHANGE token.
/// It is not used when routing via the normal Routing ENVCHANGE token.
/// </summary>
internal string DatabaseName { get; private set; }

internal RoutingInfo(byte protocol, ushort port, string serverName, string databaseName = null)
{
Protocol = protocol;
Port = port;
ServerName = servername;
ServerName = serverName;
DatabaseName = databaseName;
}
}

Expand Down
9 changes: 9 additions & 0 deletions src/Microsoft.Data.SqlClient/src/Resources/Strings.Designer.cs
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3 changes: 3 additions & 0 deletions src/Microsoft.Data.SqlClient/src/Resources/Strings.resx
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Expand Up @@ -4335,6 +4335,9 @@
<data name="SQLROR_InvalidRoutingInfo" xml:space="preserve">
<value>Invalid routing information received.</value>
</data>
<data name="SQLROR_InvalidEnhancedRoutingInfo" xml:space="preserve">
<value>Invalid enhanced routing information received.</value>
</data>
<data name="SQLROR_TimeoutAfterRoutingInfo" xml:space="preserve">
<value>Server provided routing information, but timeout already expired.</value>
</data>
Expand Down
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