Delphi ActiveX

Send CLOSE on an SSH Channel

Demonstrates the Chilkat Ssh.ChannelSendClose method, which sends an SSH CLOSE message for a channel and immediately marks it locally closed. The only argument is the channel number. It does not wait for remote EOF, remote CLOSE, or an exit status.

Background: CLOSE shuts down both directions of the channel, unlike EOF which closes only your side. Because the call returns without waiting for the remote side to acknowledge, it does not guarantee the remote process has terminated — so retrieve any output and exit status you care about before calling it. Afterward ChannelIsOpen reports false, though NumOpenChannels may still count the channel until final remote-close processing.

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var
success: Integer;
ssh: TChilkatSsh;
sshPort: Integer;
password: WideString;
channelNum: Integer;
output: WideString;

begin
success := 0;

//  Demonstrates the Ssh.ChannelSendClose method, which sends an SSH CLOSE message for a channel
//  and immediately marks it locally closed.  The only argument is the channel number.  It does
//  not wait for remote EOF, remote CLOSE, or an exit status.

ssh := TChilkatSsh.Create(Self);

sshPort := 22;
success := ssh.Connect('ssh.example.com',sshPort);
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
password := 'mySshPassword';

success := ssh.AuthenticatePw('mySshLogin',password);
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

channelNum := ssh.OpenSessionChannel();
if (channelNum < 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

success := ssh.SendReqExec(channelNum,'uptime');
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

//  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
//  it, this call waits forever if the server never sends channel close.
ssh.ReadTimeoutMs := 15000;

success := ssh.ChannelReceiveToClose(channelNum);
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

output := ssh.GetReceivedText(channelNum,'utf-8');
if (ssh.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add(output);

//  Send CLOSE for the channel.
success := ssh.ChannelSendClose(channelNum);
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

//  After a successful call, the channel is no longer reported as open.
if (ssh.ChannelIsOpen(channelNum)) then
  begin
    Memo1.Lines.Add('Still open.');
  end
else
  begin
    Memo1.Lines.Add('The channel is closed.');
  end;

ssh.Disconnect();