dockersyshome/app/Http/Controllers/Auth/LoginController.php

<?php

namespace App\Http\Controllers\Auth;

use App\Http\Controllers\Controller;
use Illuminate\Foundation\Auth\AuthenticatesUsers;
use Illuminate\Http\Request;

class LoginController extends Controller
{
    /*
    |--------------------------------------------------------------------------
    | Login Controller
    |--------------------------------------------------------------------------
    |
    | This controller handles authenticating users for the application and
    | redirecting them to their home screen. The controller uses a trait
    | to conveniently provide its functionality to your applications.
    |
    */

    use AuthenticatesUsers;

    /**
     * Where to redirect users after login.
     *
     * @var string
     */
    protected $redirectTo = '/home';

    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        $this->middleware('guest')->except('logout');
        $this->middleware('auth')->only('logout');
    }

    /**
     * Validate the user login request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return void
     *
     * @throws \Illuminate\Validation\ValidationException
     */
    protected function validateLogin(Request $request)
    {
        $request->validate([
            $this->username() => 'required|string',
            'password' => 'required|string',
            'captcha' => 'required|numeric',
        ]);

        if ($request->captcha != session('captcha_result')) {
            throw \Illuminate\Validation\ValidationException::withMessages([
                'captcha' => ['O resultado da soma está incorreto.'],
            ]);
        }
    }
}