connect method Null safety

Future<SecureSocket> connect(
  1. dynamic host,
  2. int port,
  3. {SecurityContext? context,
  4. bool onBadCertificate(
    1. X509Certificate certificate
  5. void keyLog(
    1. String line
  6. List<String>? supportedProtocols,
  7. Duration? timeout}

Constructs a new secure client socket and connects it to the given host on port port.

The returned Future will complete with a SecureSocket that is connected and ready for subscription.

The certificate provided by the server is checked using the trusted certificates set in the SecurityContext object. The default SecurityContext object contains a built-in set of trusted root certificates for well-known certificate authorities.

onBadCertificate is an optional handler for unverifiable certificates. The handler receives the X509Certificate, and can inspect it and decide (or let the user decide) whether to accept the connection or not. The handler should return true to continue the SecureSocket connection.

keyLog is an optional callback that will be called when new TLS keys are exchanged with the server. keyLog will receive one line of text in NSS Key Log Format for each call. Writing these lines to a file will allow tools (such as Wireshark) to decrypt content sent through this socket. This is meant to allow network-level debugging of secure sockets and should not be used in production code. For example:

final log = File('keylog.txt');
final socket = await SecureSocket.connect('', 443,
    keyLog: (line) => log.writeAsStringSync(line, mode: FileMode.append));

supportedProtocols is an optional list of protocols (in decreasing order of preference) to use during the ALPN protocol negotiation with the server. Example values are "http/1.1" or "h2". The selected protocol can be obtained via SecureSocket.selectedProtocol.

The argument timeout is used to specify the maximum allowed time to wait for a connection to be established. If timeout is longer than the system level timeout duration, a timeout may occur sooner than specified in timeout. On timeout, a SocketException is thrown and all ongoing connection attempts to host are cancelled.


static Future<SecureSocket> connect(host, int port,
    {SecurityContext? context,
    bool onBadCertificate(X509Certificate certificate)?,
    void keyLog(String line)?,
    List<String>? supportedProtocols,
    Duration? timeout}) {
  return RawSecureSocket.connect(host, port,
          context: context,
          onBadCertificate: onBadCertificate,
          keyLog: keyLog,
          supportedProtocols: supportedProtocols,
          timeout: timeout)
      .then((rawSocket) => new SecureSocket._(rawSocket));