Delphi ActiveX

FTP Socket Buffer and Address Options

Demonstrates the SoRcvBuf, SoSndBuf, PreferIpv6, and ClientIpAddress properties.

Background: These are low-level knobs for specific situations. Larger send/receive buffers can improve throughput on high-bandwidth, high-latency links, though the defaults suit the common case. PreferIpv6 only matters when a hostname resolves to both address families, choosing which to try first. ClientIpAddress is normally left unset; set it on a multihomed host to bind the outgoing connection to a particular local interface. Change any of these only with a concrete reason.

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var
success: Integer;
ftp: TChilkatFtp2;

begin
success := 0;

ftp := TChilkatFtp2.Create(Self);

ftp.Hostname := 'ftp.example.com';
ftp.Username := 'myFtpLogin';

//  SoRcvBuf and SoSndBuf set the TCP socket receive/send buffer sizes.  The defaults are tuned for
//  the common case; larger values can sometimes help throughput on high-latency links.
ftp.SoRcvBuf := 4194304;
ftp.SoSndBuf := 524288;

//  PreferIpv6 (default 0) chooses IPv6 over IPv4 when a hostname resolves to both.
ftp.PreferIpv6 := 0;

//  ClientIpAddress is normally left unset; set it on a multihomed host to bind the outgoing
//  connection to a specific local interface.
ftp.ClientIpAddress := '192.168.1.50';

//  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.
ftp.Password := 'myPassword';

success := ftp.Connect();
if (success = 0) then
  begin
    Memo1.Lines.Add(ftp.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Connected with custom socket options.');

success := ftp.Disconnect();
if (success = 0) then
  begin
    Memo1.Lines.Add(ftp.LastErrorText);
    Exit;
  end;