Rewrite server redirection logic. (#1499)

This is based on https://jira.mariadb.org/browse/MDEV-15935: first OK Packet can contain variable 'redirect_url' using "mariadb/mysql://[{user}[:{password}]@]{host}[:{port}]/[{db}[?{opt1}={value1}[&{opt2}={value2}]]]" format.

Introduce IConnectionPoolMetadata to unify the code between pooled and non-pooled sessions. Standardise all redirection logging to use the MySqlConnection logger, whether pooled or non-pooled.

Drop support for redirection format used by Azure Database for MySQL Single Server (which is now deprecated).

Signed-off-by: rusher <[email protected]>
Signed-off-by: Bradley Grainger <[email protected]>
Co-authored-by: Bradley Grainger <[email protected]>

Author: rusher

.ci/config/config.compression+ssl.json

@@ -4,7 +4,7 @@
       "SocketPath": "./../../../../.ci/run/mysql/mysqld.sock",
       "PasswordlessUser": "no_password",
       "SecondaryDatabase": "testdb2",
-      "UnsupportedFeatures": "RsaEncryption,CachingSha2Password,Tls12,Tls13,UuidToBin",
+      "UnsupportedFeatures": "CachingSha2Password,Redirection,RsaEncryption,Tls12,Tls13,UuidToBin",
       "MySqlBulkLoaderLocalCsvFile": "../../../TestData/LoadData_UTF8_BOM_Unix.CSV",
       "MySqlBulkLoaderLocalTsvFile": "../../../TestData/LoadData_UTF8_BOM_Unix.TSV",
       "CertificatesPath": "../../../../.ci/server/certs"

.ci/config/config.compression.json

@@ -4,7 +4,7 @@
       "SocketPath": "./../../../../.ci/run/mysql/mysqld.sock",
       "PasswordlessUser": "no_password",
       "SecondaryDatabase": "testdb2",
-      "UnsupportedFeatures": "Ed25519,QueryAttributes,StreamingResults,Tls11,UnixDomainSocket,ZeroDateTime",
+      "UnsupportedFeatures": "Ed25519,QueryAttributes,Redirection,StreamingResults,Tls11,UnixDomainSocket,ZeroDateTime",
       "MySqlBulkLoaderLocalCsvFile": "../../../../tests/TestData/LoadData_UTF8_BOM_Unix.CSV",
       "MySqlBulkLoaderLocalTsvFile": "../../../../tests/TestData/LoadData_UTF8_BOM_Unix.TSV"
     }

.ci/config/config.json

@@ -4,7 +4,7 @@
       "SocketPath": "./../../../../.ci/run/mysql/mysqld.sock",
       "PasswordlessUser": "no_password",
       "SecondaryDatabase": "testdb2",
-      "UnsupportedFeatures": "Ed25519,QueryAttributes,StreamingResults,Tls11,UnixDomainSocket,ZeroDateTime",
+      "UnsupportedFeatures": "Ed25519,QueryAttributes,Redirection,StreamingResults,Tls11,UnixDomainSocket,ZeroDateTime",
       "MySqlBulkLoaderLocalCsvFile": "../../../../tests/TestData/LoadData_UTF8_BOM_Unix.CSV",
       "MySqlBulkLoaderLocalTsvFile": "../../../../tests/TestData/LoadData_UTF8_BOM_Unix.TSV"
     }

.ci/config/config.ssl.json

@@ -4,7 +4,7 @@
       "SocketPath": "./../../../../.ci/run/mysql/mysqld.sock",
       "PasswordlessUser": "no_password",
       "SecondaryDatabase": "testdb2",
-      "UnsupportedFeatures": "RsaEncryption,CachingSha2Password,Tls12,Tls13,UuidToBin",
+      "UnsupportedFeatures": "CachingSha2Password,Redirection,RsaEncryption,Tls12,Tls13,UuidToBin",
       "MySqlBulkLoaderLocalCsvFile": "../../../../tests/TestData/LoadData_UTF8_BOM_Unix.CSV",
       "MySqlBulkLoaderLocalTsvFile": "../../../../tests/TestData/LoadData_UTF8_BOM_Unix.TSV",
       "CertificatesPath": "../../../../.ci/server/certs"

azure-pipelines.yml

@@ -136,7 +136,7 @@ jobs:
       arguments: '-c Release --no-restore'
       testRunTitle: ${{ format('{0}, $(Agent.OS), {1}, {2}', 'mysql:8.0', 'net472/net8.0', 'No SSL') }}
     env:
-      DATA__UNSUPPORTEDFEATURES: 'Ed25519,QueryAttributes,StreamingResults,Tls11,UnixDomainSocket'
+      DATA__UNSUPPORTEDFEATURES: 'Ed25519,QueryAttributes,Redirection,StreamingResults,Tls11,UnixDomainSocket'
       DATA__CONNECTIONSTRING: 'server=localhost;port=3306;user id=mysqltest;password=test;database=mysqltest;ssl mode=none;DefaultCommandTimeout=3600;AllowPublicKeyRetrieval=True;UseCompression=True'
 
 - job: windows_integration_tests_2
@@ -174,7 +174,7 @@ jobs:
       arguments: '-c Release --no-restore'
       testRunTitle: ${{ format('{0}, $(Agent.OS), {1}, {2}', 'mysql:8.0', 'net6.0', 'No SSL') }}
     env:
-      DATA__UNSUPPORTEDFEATURES: 'Ed25519,QueryAttributes,StreamingResults,Tls11,UnixDomainSocket'
+      DATA__UNSUPPORTEDFEATURES: 'Ed25519,QueryAttributes,Redirection,StreamingResults,Tls11,UnixDomainSocket'
       DATA__CONNECTIONSTRING: 'server=localhost;port=3306;user id=mysqltest;password=test;database=mysqltest;ssl mode=none;DefaultCommandTimeout=3600;AllowPublicKeyRetrieval=True'
 
 - job: linux_integration_tests
@@ -187,27 +187,27 @@ jobs:
       'MySQL 8.0':
         image: 'mysql:8.0'
         connectionStringExtra: 'AllowPublicKeyRetrieval=True'
-        unsupportedFeatures: 'Ed25519,StreamingResults,Tls11,ZeroDateTime'
+        unsupportedFeatures: 'Ed25519,Redirection,StreamingResults,Tls11,ZeroDateTime'
       'MySQL 8.4':
         image: 'mysql:8.4'
         connectionStringExtra: 'AllowPublicKeyRetrieval=True'
-        unsupportedFeatures: 'Ed25519,StreamingResults,Tls11,ZeroDateTime'
+        unsupportedFeatures: 'Ed25519,Redirection,StreamingResults,Tls11,ZeroDateTime'
       'MySQL 9.0':
         image: 'mysql:9.0'
         connectionStringExtra: 'AllowPublicKeyRetrieval=True'
-        unsupportedFeatures: 'Ed25519,StreamingResults,Tls11,ZeroDateTime'
+        unsupportedFeatures: 'Ed25519,Redirection,StreamingResults,Tls11,ZeroDateTime'
       'MariaDB 10.6':
         image: 'mariadb:10.6'
         connectionStringExtra: ''
-        unsupportedFeatures: 'CachingSha2Password,CancelSleepSuccessfully,Json,RoundDateTime,QueryAttributes,Sha256Password,Tls11,UuidToBin'
+        unsupportedFeatures: 'CachingSha2Password,CancelSleepSuccessfully,Json,RoundDateTime,QueryAttributes,Sha256Password,Tls11,UuidToBin,Redirection'
       'MariaDB 10.11':
         image: 'mariadb:10.11'
         connectionStringExtra: ''
-        unsupportedFeatures: 'CachingSha2Password,CancelSleepSuccessfully,Json,RoundDateTime,QueryAttributes,Sha256Password,Tls11,UuidToBin'
+        unsupportedFeatures: 'CachingSha2Password,CancelSleepSuccessfully,Json,RoundDateTime,QueryAttributes,Sha256Password,Tls11,UuidToBin,Redirection'
       'MariaDB 11.4':
         image: 'mariadb:11.4'
         connectionStringExtra: ''
-        unsupportedFeatures: 'CachingSha2Password,CancelSleepSuccessfully,Json,RoundDateTime,QueryAttributes,Sha256Password,Tls11,UuidToBin'
+        unsupportedFeatures: 'CachingSha2Password,CancelSleepSuccessfully,Json,RoundDateTime,QueryAttributes,Sha256Password,Tls11,UuidToBin,Redirection'
   steps:
   - template: '.ci/integration-tests-steps.yml'
     parameters:

src/MySqlConnector/Core/ConnectionPool.cs

@@ -8,10 +8,16 @@
 
 namespace MySqlConnector.Core;
 
-internal sealed class ConnectionPool : IDisposable
+internal sealed class ConnectionPool : IConnectionPoolMetadata, IDisposable
 {
 	public int Id { get; }
 
+	ConnectionPool? IConnectionPoolMetadata.ConnectionPool => this;
+
+	int IConnectionPoolMetadata.Generation => m_generation;
+
+	int IConnectionPoolMetadata.GetNewSessionId() => Interlocked.Increment(ref m_lastSessionId); 
+
 	public string? Name { get; }
 
 	public ConnectionSettings ConnectionSettings { get; }
@@ -95,6 +101,7 @@ public async ValueTask<ServerSession> GetSessionAsync(MySqlConnection connection
 						m_leasedSessions.Add(session.Id, session);
 						leasedSessionsCountPooled = m_leasedSessions.Count;
 					}
+
 					MetricsReporter.AddUsed(this);
 					ActivitySourceHelper.CopyTags(session.ActivityTags, activity);
 					Log.ReturningPooledSession(m_logger, Id, session.Id, leasedSessionsCountPooled);
@@ -106,7 +113,8 @@ public async ValueTask<ServerSession> GetSessionAsync(MySqlConnection connection
 			}
 
 			// create a new session
-			session = await ConnectSessionAsync(connection, s_createdNewSession, startingTimestamp, activity, ioBehavior, cancellationToken).ConfigureAwait(false);
+			session = await ServerSession.ConnectAndRedirectAsync(m_connectionLogger, m_logger, this, ConnectionSettings, m_loadBalancer,
+				connection, s_createdNewSession, startingTimestamp, activity, ioBehavior, cancellationToken).ConfigureAwait(false);
 			AdjustHostConnectionCount(session, 1);
 			session.OwningConnection = new(connection);
 			int leasedSessionsCountNew;
@@ -402,7 +410,8 @@ private async Task CreateMinimumPooledSessions(MySqlConnection connection, IOBeh
 
 			try
 			{
-				var session = await ConnectSessionAsync(connection, s_createdToReachMinimumPoolSize, Stopwatch.GetTimestamp(), null, ioBehavior, cancellationToken).ConfigureAwait(false);
+				var session = await ServerSession.ConnectAndRedirectAsync(m_connectionLogger, m_logger, this, ConnectionSettings, m_loadBalancer,
+					connection, s_createdToReachMinimumPoolSize, Stopwatch.GetTimestamp(), null, ioBehavior, cancellationToken).ConfigureAwait(false);
 				AdjustHostConnectionCount(session, 1);
 				lock (m_sessions)
 					_ = m_sessions.AddFirst(session);
@@ -416,81 +425,6 @@ private async Task CreateMinimumPooledSessions(MySqlConnection connection, IOBeh
 		}
 	}
 
-	private async ValueTask<ServerSession> ConnectSessionAsync(MySqlConnection connection, Action<ILogger, int, string, Exception?> logMessage, long startingTimestamp, Activity? activity, IOBehavior ioBehavior, CancellationToken cancellationToken)
-	{
-		var session = new ServerSession(m_connectionLogger, this, m_generation, Interlocked.Increment(ref m_lastSessionId));
-		if (m_logger.IsEnabled(LogLevel.Debug))
-			logMessage(m_logger, Id, session.Id, null);
-		string? statusInfo;
-		try
-		{
-			statusInfo = await session.ConnectAsync(ConnectionSettings, connection, startingTimestamp, m_loadBalancer, activity, ioBehavior, cancellationToken).ConfigureAwait(false);
-		}
-		catch (Exception)
-		{
-			await session.DisposeAsync(ioBehavior, default).ConfigureAwait(false);
-			throw;
-		}
-
-		Exception? redirectionException = null;
-		if (statusInfo is not null && statusInfo.StartsWith("Location: mysql://", StringComparison.Ordinal))
-		{
-			// server redirection string has the format "Location: mysql://{host}:{port}/user={userId}[&ttl={ttl}]"
-			Log.HasServerRedirectionHeader(m_logger, session.Id, statusInfo);
-
-			if (ConnectionSettings.ServerRedirectionMode == MySqlServerRedirectionMode.Disabled)
-			{
-				Log.ServerRedirectionIsDisabled(m_logger, Id);
-			}
-			else if (Utility.TryParseRedirectionHeader(statusInfo, out var host, out var port, out var user))
-			{
-				if (host != ConnectionSettings.HostNames![0] || port != ConnectionSettings.Port || user != ConnectionSettings.UserID)
-				{
-					var redirectedSettings = ConnectionSettings.CloneWith(host, port, user);
-					Log.OpeningNewConnection(m_logger, Id, host, port, user);
-					var redirectedSession = new ServerSession(m_connectionLogger, this, m_generation, Interlocked.Increment(ref m_lastSessionId));
-					try
-					{
-						_ = await redirectedSession.ConnectAsync(redirectedSettings, connection, startingTimestamp, m_loadBalancer, activity, ioBehavior, cancellationToken).ConfigureAwait(false);
-					}
-					catch (Exception ex)
-					{
-						Log.FailedToConnectRedirectedSession(m_logger, ex, Id, redirectedSession.Id);
-						redirectionException = ex;
-					}
-
-					if (redirectionException is null)
-					{
-						Log.ClosingSessionToUseRedirectedSession(m_logger, Id, session.Id, redirectedSession.Id);
-						await session.DisposeAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
-						return redirectedSession;
-					}
-					else
-					{
-						try
-						{
-							await redirectedSession.DisposeAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
-						}
-						catch (Exception)
-						{
-						}
-					}
-				}
-				else
-				{
-					Log.SessionAlreadyConnectedToServer(m_logger, session.Id);
-				}
-			}
-		}
-
-		if (ConnectionSettings.ServerRedirectionMode == MySqlServerRedirectionMode.Required)
-		{
-			Log.RequiresServerRedirection(m_logger, Id);
-			throw new MySqlException(MySqlErrorCode.UnableToConnectToHost, "Server does not support redirection", redirectionException);
-		}
-		return session;
-	}
-
 	public static ConnectionPool? CreatePool(string connectionString, MySqlConnectorLoggingConfiguration loggingConfiguration, string? name)
 	{
 		// parse connection string and check for 'Pooling' setting; return 'null' if pooling is disabled

src/MySqlConnector/Core/ConnectionSettings.cs

@@ -270,8 +270,12 @@ public int ConnectionTimeoutMilliseconds
 
 	private ConnectionSettings(ConnectionSettings other, string host, int port, string userId)
 	{
-		ConnectionStringBuilder = other.ConnectionStringBuilder;
-		ConnectionString = other.ConnectionString;
+		ConnectionStringBuilder = new MySqlConnectionStringBuilder(other.ConnectionString);
+		ConnectionStringBuilder.Port = (uint)port;
+		ConnectionStringBuilder.Server = host;
+		ConnectionStringBuilder.UserID = userId;
+
+		ConnectionString = ConnectionStringBuilder.ConnectionString;
 
 		ConnectionProtocol = MySqlConnectionProtocol.Sockets;
 		HostNames = [host];

src/MySqlConnector/Core/IConnectionPoolMetadata.cs

@@ -0,0 +1,26 @@
+namespace MySqlConnector.Core;
+
+internal interface IConnectionPoolMetadata
+{
+	/// <summary>
+	/// Returns the <see cref="ConnectionPool"/> this <see cref="IConnectionPoolMetadata"/> is associated with,
+	/// or <c>null</c> if it represents a non-pooled connection.
+	/// </summary>
+	ConnectionPool? ConnectionPool { get; }
+
+	/// <summary>
+	/// Returns the ID of the connection pool, or 0 if this is a non-pooled connection.
+	/// </summary>
+	int Id { get; }
+
+	/// <summary>
+	/// Returns the generation of the connection pool, or 0 if this is a non-pooled connection.
+	/// </summary>
+	int Generation { get; }
+
+	/// <summary>
+	/// Returns a new session ID.
+	/// </summary>
+	/// <returns>A new session ID.</returns>
+	int GetNewSessionId();
+}

src/MySqlConnector/Core/NonPooledConnectionPoolMetadata.cs

@@ -0,0 +1,13 @@
+namespace MySqlConnector.Core;
+
+internal sealed class NonPooledConnectionPoolMetadata : IConnectionPoolMetadata
+{
+	public static IConnectionPoolMetadata Instance { get; } = new NonPooledConnectionPoolMetadata();
+
+	public ConnectionPool? ConnectionPool => null;
+	public int Id => 0;
+	public int Generation => 0;
+	public int GetNewSessionId() => Interlocked.Increment(ref m_lastId);
+
+	private int m_lastId;
+}