/// <summary>
/// Opens a FXP PASV connection between the source FTP Server and the destination FTP Server
/// </summary>
/// <param name="remoteClient">Valid FTP connection to the destination FTP Server</param>
/// <returns>A data stream ready to be used</returns>
private async Task <FtpFxpSession> OpenPassiveFXPConnectionAsync(FtpClient remoteClient, bool trackProgress, CancellationToken token)
{
FtpReply reply;
Match m;
FtpClient sourceClient = null;
FtpClient destinationClient = null;
FtpClient progressClient = null;
// create a new connection to the source FTP server if EnableThreadSafeDataConnections is set
if (m_threadSafeDataChannels)
{
sourceClient = CloneConnection();
sourceClient._AutoDispose = true;
sourceClient.CopyStateFlags(this);
await sourceClient.ConnectAsync(token);
await sourceClient.SetWorkingDirectoryAsync(await GetWorkingDirectoryAsync(token), token);
}
else
{
sourceClient = this;
}
// create a new connection to the target FTP server if EnableThreadSafeDataConnections is set
if (remoteClient.EnableThreadSafeDataConnections)
{
destinationClient = remoteClient.CloneConnection();
destinationClient._AutoDispose = true;
destinationClient.CopyStateFlags(remoteClient);
await destinationClient.ConnectAsync(token);
await destinationClient.SetWorkingDirectoryAsync(await remoteClient.GetWorkingDirectoryAsync(token), token);
}
else
{
destinationClient = remoteClient;
}
// create a new connection to the target FTP server to track progress
// if progress tracking is enabled during this FXP transfer
if (trackProgress)
{
progressClient = remoteClient.CloneConnection();
progressClient._AutoDispose = true;
progressClient.CopyStateFlags(remoteClient);
await progressClient.ConnectAsync(token);
await progressClient.SetWorkingDirectoryAsync(await remoteClient.GetWorkingDirectoryAsync(token), token);
}
await sourceClient.SetDataTypeAsync(sourceClient.FXPDataType, token);
await destinationClient.SetDataTypeAsync(destinationClient.FXPDataType, token);
// send PASV command to destination FTP server to get passive port to be used from source FTP server
if (!(reply = await destinationClient.ExecuteAsync("PASV", token)).Success)
{
throw new FtpCommandException(reply);
}
m = Regex.Match(reply.Message, @"(?<quad1>\d+)," + @"(?<quad2>\d+)," + @"(?<quad3>\d+)," + @"(?<quad4>\d+)," + @"(?<port1>\d+)," + @"(?<port2>\d+)");
if (!m.Success || m.Groups.Count != 7)
{
throw new FtpException("Malformed PASV response: " + reply.Message);
}
// Instruct source server to open a connection to the destination Server
if (!(reply = await sourceClient.ExecuteAsync($"PORT {m.Value}", token)).Success)
{
throw new FtpCommandException(reply);
}
// the FXP session stores the active connections used for this FXP transfer
return(new FtpFxpSession {
SourceServer = sourceClient,
TargetServer = destinationClient,
ProgressServer = progressClient,
});
}