telnet 1.0.4

telnet: ^1.0.4 copied to clipboard

example/telnet_example.dart

import 'package:telnet/telnet.dart';

const host = "127.0.0.1";
const port = 23;
const username = "root";
const password = "admin";
var hasLogin = false;
const echoEnabled = true;

void main() async {
  // Create a Telnet connection task.
  final task = TelnetClient.startConnect(
    host: host,
    port: port,
    onError: onError,
    onDone: onDone,
    onEvent: onEvent,
  );

  // Cancel the connection task.
  // task.cancel();

  // Wait the connection task finished.
  await task.waitDone();

  // Get the `TelnetClient` instance. It will be `null` if connect failed.
  final client = task.client;
  if (client == null) {
    print("Fail to connect to $host:$port");
  } else {
    print("Successfully connect to $host:$port");
  }

  await Future.delayed(const Duration(seconds: 15));

  // Close the Telnet connection.
  await client?.terminate();
}

void onError(TelnetClient? client, dynamic error) {
  print("[ERROR] $error");
}

void onDone(TelnetClient? client) {
  print("[DONE]");
}

void onEvent(TelnetClient? client, TLMsgEvent event) {
  if (event.type == TLMsgEventType.write) {
    print("[WRITE] ${event.msg}");

  } else if (event.type == TLMsgEventType.read) {
    print("[READ] ${event.msg}");

    if (event.msg is TLOptMsg) {
      final cmd = (event.msg as TLOptMsg).cmd; // Telnet Negotiation Command.
      final opt = (event.msg as TLOptMsg).opt; // Telnet Negotiation Option.

      if (cmd == TLCmd.wont) {
        client?.write(TLOptMsg(TLCmd.doNot, opt));              // Write [IAC DO opt].
      } else if (cmd == TLCmd.doNot) {
        client?.write(TLOptMsg(TLCmd.wont, opt));               // Write [IAC WON'T opt].
      } else {
        switch(opt.code) {
          case 0x01: { // ECHO
            if (cmd == TLCmd.doIt) {
              if (echoEnabled) {
                client?.write(TLOptMsg(TLCmd.will, opt));       // Write [IAC WILL ECHO].
              } else {
                client?.write(TLOptMsg(TLCmd.wont, opt));       // Write [IAC WON'T ECHO].
              }
            } else if (cmd == TLCmd.will) {
              if (echoEnabled) {
                client?.write(TLOptMsg(TLCmd.doIt, opt));       // Write [IAC DO ECHO].
              } else {
                client?.write(TLOptMsg(TLCmd.doNot, opt));      // Write [IAC DON'T ECHO].
              }
            }
          } break;
          case 0x03: { // SUPPRESS GO AHEAD
            if (cmd == TLCmd.will) {
              client?.write(TLOptMsg(TLCmd.doIt, opt));         // Write [IAC DO SUPPRESS_GO_AHEAD].
            }
          } break;
          case 0x12: { // LOGOUT
            // Pass
          } break;
          case 0x18: { // TERMINAL TYPE
            if (cmd == TLCmd.doIt) {
              client?.writeAll([
                TLOptMsg(TLCmd.will, opt),                      // Write [IAC WILL TERMINAL_TYPE].
                TLSubMsg(opt, [0x00, 0x41, 0x4E, 0x53, 0x49]),  // Write [IAC SB TERMINAL_TYPE IS ANSI IAC SE].
              ]);
            }
          } break;
          case 0x1F: { // WINDOW SIZE
            if (cmd == TLCmd.doIt) {
              client?.writeAll([
                TLOptMsg(TLCmd.will, opt),                      // Write [IAC WILL WINDOW_SIZE].
                TLSubMsg(opt, [0x00, 0x5A, 0x00, 0x18]),        // Write [IAC SB WINDOW_SIZE 90 24 IAC SE].
              ]);
            }
          } break;
          default: {
            if (cmd == TLCmd.doIt) {
              client?.write(TLOptMsg(TLCmd.wont, opt));         // Write [IAC WON'T opt].
            } else if (cmd == TLCmd.will) {
              client?.write(TLOptMsg(TLCmd.doNot, opt));        // Write [IAC DON'T opt].
            }
          }
        }
      }

    } else if (!hasLogin && event.msg is TLTextMsg) {

      final text = (event.msg as TLTextMsg).text.toLowerCase();
      if (text.contains("welcome")) {
        hasLogin = true;
        print("[INFO] Login OK!");
      } else if (text.contains("login:") || text.contains("username:")) {
        client!.write(TLTextMsg("$username\r\n"));              // Write [username].
      } else if (text.contains("password:")) {
        client!.write(TLTextMsg("$password\r\n"));              // Write [password].
      }

    }
  }
}