Use correct hostname when cancelling query. Fixes #1514

Connect directly to the cancelled command's session's IP address but maintain the hostname for SSL certificate validation.

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

src/MySqlConnector/Core/ConnectionSettings.cs

@@ -1,6 +1,7 @@
 #if NETCOREAPP3_0_OR_GREATER
 using System.Net.Security;
 #endif
+using System.Net;
 using System.Security.Authentication;
 using MySqlConnector.Utilities;
 
@@ -150,7 +151,9 @@ public ConnectionSettings(MySqlConnectionStringBuilder csb)
 		static int ToSigned(uint value) => value >= int.MaxValue ? int.MaxValue : (int) value;
 	}
 
-	public ConnectionSettings CloneWith(string host, int port, string userId) => new(this, host, port, userId);
+	public ConnectionSettings CloneWith(string host, int port, string userId) => new(this, host, port, userId, null);
+
+	public ConnectionSettings CloneWith(IPAddress ipAddress) => new(this, HostNames![0], Port, UserID, ipAddress);
 
 	private static MySqlGuidFormat GetEffectiveGuidFormat(MySqlGuidFormat guidFormat, bool oldGuids)
 	{
@@ -182,6 +185,7 @@ private static MySqlGuidFormat GetEffectiveGuidFormat(MySqlGuidFormat guidFormat
 	public string ConnectionString { get; }
 	public MySqlConnectionProtocol ConnectionProtocol { get; }
 	public IReadOnlyList<string>? HostNames { get; }
+	public IPAddress? IPAddress { get; }
 	public MySqlLoadBalance LoadBalance { get; }
 	public int Port { get; }
 	public string PipeName { get; }
@@ -268,17 +272,18 @@ public int ConnectionTimeoutMilliseconds
 		}
 	}
 
-	private ConnectionSettings(ConnectionSettings other, string host, int port, string userId)
+	private ConnectionSettings(ConnectionSettings other, string host, int port, string userId, IPAddress? ipAddress)
 	{
 		ConnectionStringBuilder = new MySqlConnectionStringBuilder(other.ConnectionString);
-		ConnectionStringBuilder.Port = (uint)port;
+		ConnectionStringBuilder.Port = (uint) port;
 		ConnectionStringBuilder.Server = host;
 		ConnectionStringBuilder.UserID = userId;
 
 		ConnectionString = ConnectionStringBuilder.ConnectionString;
 
 		ConnectionProtocol = MySqlConnectionProtocol.Sockets;
 		HostNames = [host];
+		IPAddress = ipAddress;
 		LoadBalance = other.LoadBalance;
 		Port = port;
 		PipeName = other.PipeName;

src/MySqlConnector/Core/ServerSession.cs

@@ -1164,13 +1164,20 @@ private async Task<bool> OpenTcpSocketAsync(ConnectionSettings cs, ILoadBalancer
 			IPAddress[] ipAddresses;
 			try
 			{
-				ipAddresses = ioBehavior == IOBehavior.Asynchronous
+				if (cs.IPAddress is { } ipAddress)
+				{
+					ipAddresses = [ipAddress];
+				}
+				else
+				{
+					ipAddresses = ioBehavior == IOBehavior.Asynchronous
 #if NET6_0_OR_GREATER
-					? await Dns.GetHostAddressesAsync(hostName, cancellationToken).ConfigureAwait(false)
+						? await Dns.GetHostAddressesAsync(hostName, cancellationToken).ConfigureAwait(false)
 #else
-					? await Dns.GetHostAddressesAsync(hostName).ConfigureAwait(false)
+						? await Dns.GetHostAddressesAsync(hostName).ConfigureAwait(false)
 #endif
-					: Dns.GetHostAddresses(hostName);
+						: Dns.GetHostAddresses(hostName);
+				}
 			}
 			catch (SocketException ex)
 			{

src/MySqlConnector/MySqlConnection.cs

@@ -896,16 +896,27 @@ internal void Cancel(ICancellableCommand command, int commandId, bool isCancel)
 				AutoEnlist = false,
 				Pooling = false,
 			};
-			if (session.IPEndPoint is { Address: { } ipAddress, Port: { } port })
+
+			// connect directly to the session's IP address to ensure we're cancelling the query on the right server (in a load-balanced scenario)
+			IPAddress? ipAddress = null;
+			if (session.IPEndPoint is { Address: { } sessionIpAddress, Port: { } port })
 			{
-				csb.Server = ipAddress.ToString();
+				// set the hostname to the existing session's hostname (for SSL validation)
+				csb.Server = session.HostName;
 				csb.Port = (uint) port;
+				ipAddress = sessionIpAddress;
 			}
 			csb.UserID = session.UserID;
 			var cancellationTimeout = GetConnectionSettings().CancellationTimeout;
 			csb.ConnectionTimeout = cancellationTimeout < 1 ? 3u : (uint) cancellationTimeout;
 
+			// forcibly set the IP address the new connection should use
+			var connectionSettings = new ConnectionSettings(csb);
+			if (ipAddress is not null)
+				connectionSettings = connectionSettings.CloneWith(ipAddress);
+
 			using var connection = CloneWith(csb.ConnectionString);
+			connection.m_connectionSettings = connectionSettings;
 			connection.Open();
 #if NET6_0_OR_GREATER
 			var killQuerySql = string.Create(CultureInfo.InvariantCulture, $"KILL QUERY {command.Connection!.ServerThread}");