Dart

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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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final ftp = CkFtp2();

  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 false) chooses IPv6 over IPv4 when a hostname resolves to both.
  ftp.preferIpv6 = false;

  // 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';

  try {
    ftp.connect();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Connected with custom socket options.');

  try {
    ftp.disconnect();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }
}