// TODO: add example
/// <summary>
/// Connect to the server
/// </summary>
/// <exception cref="ObjectDisposedException">Thrown if this object has been disposed.</exception>
public virtual async Task ConnectAsync(CancellationToken token = default(CancellationToken))
{
FtpReply reply;
LogFunc(nameof(ConnectAsync));
if (IsDisposed)
{
throw new ObjectDisposedException("This FtpClient object has been disposed. It is no longer accessible.");
}
if (m_stream == null)
{
m_stream = new FtpSocketStream(this);
m_stream.ValidateCertificate += new FtpSocketStreamSslValidation(FireValidateCertficate);
}
else
{
if (IsConnected)
{
Disconnect();
}
}
if (Host == null)
{
throw new FtpException("No host has been specified");
}
if (m_capabilities == null)
{
m_capabilities = new List <FtpCapability>();
}
ResetStateFlags();
m_hashAlgorithms = FtpHashAlgorithm.NONE;
m_stream.ConnectTimeout = m_connectTimeout;
m_stream.SocketPollInterval = m_socketPollInterval;
await ConnectAsync(m_stream, token);
m_stream.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, m_keepAlive);
#if !NO_SSL
if (EncryptionMode == FtpEncryptionMode.Implicit)
{
await m_stream.ActivateEncryptionAsync(Host, m_clientCerts.Count > 0?m_clientCerts : null, m_SslProtocols);
}
#endif
await HandshakeAsync(token);
m_serverType = FtpServerSpecificHandler.DetectFtpServer(this, HandshakeReply);
if (SendHost)
{
if (!(reply = await ExecuteAsync("HOST " + (SendHostDomain != null ? SendHostDomain : Host), token)).Success)
{
throw new FtpException("HOST command failed.");
}
}
#if !NO_SSL
// try to upgrade this connection to SSL if supported by the server
if (EncryptionMode == FtpEncryptionMode.Explicit || EncryptionMode == FtpEncryptionMode.Auto)
{
reply = await ExecuteAsync("AUTH TLS", token);
if (!reply.Success)
{
_ConnectionFTPSFailure = true;
if (EncryptionMode == FtpEncryptionMode.Explicit)
{
throw new FtpSecurityNotAvailableException("AUTH TLS command failed.");
}
}
else if (reply.Success)
{
await m_stream.ActivateEncryptionAsync(Host, m_clientCerts.Count > 0?m_clientCerts : null, m_SslProtocols);
}
}
#endif
if (m_credentials != null)
{
await AuthenticateAsync(token);
}
// configure the default FTPS settings
if (IsEncrypted && DataConnectionEncryption)
{
if (!(reply = await ExecuteAsync("PBSZ 0", token)).Success)
{
throw new FtpCommandException(reply);
}
if (!(reply = await ExecuteAsync("PROT P", token)).Success)
{
throw new FtpCommandException(reply);
}
}
// if this is a clone these values should have already been loaded
// so save some bandwidth and CPU time and skip executing this again.
// otherwise clear the capabilities in case connection is reused to
// a different server
if (!m_isClone && m_checkCapabilities)
{
m_capabilities.Clear();
}
bool assumeCaps = false;
if (m_capabilities.IsBlank() && m_checkCapabilities)
{
if ((reply = await ExecuteAsync("FEAT", token)).Success && reply.InfoMessages != null)
{
GetFeatures(reply);
}
else
{
assumeCaps = true;
}
}
// Enable UTF8 if the encoding is ASCII and UTF8 is supported
if (m_textEncodingAutoUTF && m_textEncoding == Encoding.ASCII && HasFeature(FtpCapability.UTF8))
{
m_textEncoding = Encoding.UTF8;
}
LogStatus(FtpTraceLevel.Info, "Text encoding: " + m_textEncoding.ToString());
if (m_textEncoding == Encoding.UTF8)
{
// If the server supports UTF8 it should already be enabled and this
// command should not matter however there are conflicting drafts
// about this so we'll just execute it to be safe.
if ((reply = await ExecuteAsync("OPTS UTF8 ON", token)).Success)
{
_ConnectionUTF8Success = true;
}
}
// Get the system type - Needed to auto-detect file listing parser
if ((reply = await ExecuteAsync("SYST", token)).Success)
{
m_systemType = reply.Message;
m_serverType = FtpServerSpecificHandler.DetectFtpServerBySyst(this);
m_serverOS = FtpServerSpecificHandler.DetectFtpOSBySyst(this);
}
// Set a FTP server handler if a custom handler has not already been set
if (ServerHandler == null)
{
ServerHandler = FtpServerSpecificHandler.GetServerHandler(m_serverType);
}
// Assume the system's capabilities if FEAT command not supported by the server
if (assumeCaps)
{
FtpServerSpecificHandler.AssumeCapabilities(this, ServerHandler, m_capabilities, ref m_hashAlgorithms);
}
#if !NO_SSL && !CORE
if (IsEncrypted && PlainTextEncryption)
{
if (!(reply = await ExecuteAsync("CCC", token)).Success)
{
throw new FtpSecurityNotAvailableException("Failed to disable encryption with CCC command. Perhaps your server does not support it or is not configured to allow it.");
}
else
{
// close the SslStream and send close_notify command to server
m_stream.DeactivateEncryption();
// read stale data (server's reply?)
await ReadStaleDataAsync(false, true, false, token);
}
}
#endif
// Unless a custom list parser has been set,
// Detect the listing parser and prefer machine listings over any other type
// FIX : #739 prefer using machine listings to fix issues with GetListing and DeleteDirectory
if (ListingParser != FtpParser.Custom)
{
ListingParser = ServerHandler != null?ServerHandler.GetParser() : FtpParser.Auto;
if (HasFeature(FtpCapability.MLSD))
{
ListingParser = FtpParser.Machine;
}
}
// Create the parser even if the auto-OS detection failed
m_listParser.Init(m_serverOS, ListingParser);
// FIX : #318 always set the type when we create a new connection
ForceSetDataType = true;
// Execute server-specific post-connection event
if (ServerHandler != null)
{
await ServerHandler.AfterConnectedAsync(this, token);
}
}