Delphi ActiveX

Get Received SSH Bytes into a BinData

Demonstrates the Chilkat Ssh.GetReceivedBd method, which appends the bytes currently in a channel's normal receive buffer to a BinData. The first argument is the channel number and the second is the BinData. The channel receive buffer is cleared afterward; existing bytes in the BinData are preserved.

Background: When the remote command emits binary — a tarball, an image, a compressed stream — decoding it as text through a charset would corrupt it. BinData keeps the bytes exactly as received, so you can write them to a file, hash them, or hand them to another API. Like the StringBuilder form it appends, making it easy to accumulate across successive reads. On failure the BinData is left unchanged.

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var
success: Integer;
ssh: TChilkatSsh;
sshPort: Integer;
password: WideString;
channelNum: Integer;
bd: TChilkatBinData;

begin
success := 0;

//  Demonstrates the Ssh.GetReceivedBd method, which appends the bytes currently in a channel's
//  receive buffer to a BinData.  The 1st argument is the channel number and the 2nd is the
//  BinData.  The channel receive buffer is cleared afterward.

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;

//  Run a command whose output may be binary.
success := ssh.SendReqExec(channelNum,'cat /usr/bin/hostname');
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;

//  Append the raw received bytes to a BinData.  Existing bytes in the BinData are preserved.
bd := TChilkatBinData.Create(Self);
success := ssh.GetReceivedBd(channelNum,bd.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Bytes received: ' + IntToStr(bd.NumBytes));

ssh.Disconnect();