Delphi DLL

Send EOF on an SSH Channel

Demonstrates the Chilkat Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel. The only argument is the channel number. EOF closes only the client-to-server direction; the application may still receive stdout, stderr, exit status, EOF, and CLOSE from the server.

Background: Many remote commands read standard input until it ends — wc, sort, cat and friends. Sending EOF is the SSH equivalent of pressing Ctrl+D: it tells the remote process no more input is coming so it can finish and emit results. After sending EOF, do not send more data on that channel; a later send may return true even though nothing is delivered.

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var
success: Boolean;
ssh: HCkSsh;
sshPort: Integer;
password: PWideChar;
channelNum: Integer;
output: PWideChar;

begin
success := False;

//  Demonstrates the Ssh.ChannelSendEof method, which sends an SSH EOF message on a channel.  The
//  only argument is the channel number.  EOF closes only the client-to-server direction; output
//  may still be received from the server.

ssh := CkSsh_Create();

sshPort := 22;
success := CkSsh_Connect(ssh,'ssh.example.com',sshPort);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    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 := CkSsh_AuthenticatePw(ssh,'mySshLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

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

success := CkSsh_SendReqExec(ssh,channelNum,'wc -l');
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  Send input to the remote command.
success := CkSsh_ChannelSendString(ssh,channelNum,'line one' + #10 + 'line two' + #10 + 'line three' + #10,'utf-8');
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

//  Signal that no more input will be sent.  Do not send more data on this channel afterward.
success := CkSsh_ChannelSendEof(ssh,channelNum);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    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.
CkSsh_putReadTimeoutMs(ssh,15000);

//  Output can still be received after EOF is sent.
success := CkSsh_ChannelReceiveToClose(ssh,channelNum);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;

output := CkSsh__getReceivedText(ssh,channelNum,'utf-8');
if (CkSsh_getLastMethodSuccess(ssh) = False) then
  begin
    Memo1.Lines.Add(CkSsh__lastErrorText(ssh));
    Exit;
  end;
Memo1.Lines.Add(output);

CkSsh_Disconnect(ssh);

CkSsh_Dispose(ssh);