defaultGatewayIp function

String? defaultGatewayIp()

Returns the host machine's default-route gateway IP address.

Runs ip route and parses the line that starts with default to extract the gateway address, e.g. 172.17.0.1. This is the address through which a container inside a Docker bridge network can reach the host.

Returns null if:

• the ip command is not available on the current platform,
• the command exits with a non-zero status,
• no default route is present, or
• any other I/O error occurs.

Implementation

String? defaultGatewayIp() {
  try {
    final result = Process.runSync(
      'sh',
      ['-c', "ip route|awk '/default/ { print \$3 }'"],
    );
    if (result.exitCode != 0) {
      return null;
    }
    final ip = result.stdout.toString().trim();
    return ip.isNotEmpty ? ip : null;
  } catch (_) {
    return null;
  }
}