private async Task <bool> OpenTcpSocketAsync(ConnectionSettings cs, ILoadBalancer loadBalancer, IOBehavior ioBehavior, CancellationToken cancellationToken)
{
var hostNames = loadBalancer.LoadBalance(cs.HostNames);
foreach (var hostName in hostNames)
{
IPAddress[] ipAddresses;
try
{
#if NETSTANDARD1_3
// Dns.GetHostAddresses isn't available until netstandard 2.0: https://github.com/dotnet/corefx/pull/11950
ipAddresses = await Dns.GetHostAddressesAsync(hostName).ConfigureAwait(false);
#else
if (ioBehavior == IOBehavior.Asynchronous)
{
ipAddresses = await Dns.GetHostAddressesAsync(hostName).ConfigureAwait(false);
}
else
{
ipAddresses = Dns.GetHostAddresses(hostName);
}
#endif
}
catch (SocketException)
{
// name couldn't be resolved
continue;
}
// need to try IP Addresses one at a time: https://github.com/dotnet/corefx/issues/5829
foreach (var ipAddress in ipAddresses)
{
TcpClient tcpClient = null;
try
{
tcpClient = new TcpClient(ipAddress.AddressFamily);
using (cancellationToken.Register(() => tcpClient?.Client?.Dispose()))
{
try
{
if (ioBehavior == IOBehavior.Asynchronous)
{
await tcpClient.ConnectAsync(ipAddress, cs.Port).ConfigureAwait(false);
}
else
{
#if NETSTANDARD1_3
await tcpClient.ConnectAsync(ipAddress, cs.Port).ConfigureAwait(false);
#else
if (Utility.IsWindows())
{
tcpClient.Connect(ipAddress, cs.Port);
}
else
{
// non-windows platforms block on synchronous connect, use send/receive timeouts: https://github.com/dotnet/corefx/issues/20954
var originalSendTimeout = tcpClient.Client.SendTimeout;
var originalReceiveTimeout = tcpClient.Client.ReceiveTimeout;
tcpClient.Client.SendTimeout = cs.ConnectionTimeoutMilliseconds;
tcpClient.Client.ReceiveTimeout = cs.ConnectionTimeoutMilliseconds;
tcpClient.Connect(ipAddress, cs.Port);
tcpClient.Client.SendTimeout = originalSendTimeout;
tcpClient.Client.ReceiveTimeout = originalReceiveTimeout;
}
#endif
}
}
catch (ObjectDisposedException ex) when(cancellationToken.IsCancellationRequested)
{
throw new MySqlException("Connect Timeout expired.", ex);
}
}
}
catch (SocketException)
{
tcpClient?.Client?.Dispose();
continue;
}
HostName = hostName;
m_tcpClient = tcpClient;
m_socket = m_tcpClient.Client;
m_networkStream = m_tcpClient.GetStream();
m_socket.SetKeepAlive(cs.Keepalive);
lock (m_lock)
m_state = State.Connected;
return(true);
}
}
return(false);
}
