iot/projects/Infrastructure/Web/Mvc/CaptchaController.cs

using System;
using System.Security.Cryptography;
using System.Text;
using Infrastructure.Extensions;
using Infrastructure.Security;
using Infrastructure.Web.DataAnnotations;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace Infrastructure.Web.Mvc
{
    public class CaptchaController : Controller
    {
        private readonly ILogger<CaptchaController> _logger;
        private readonly IWebHostEnvironment _env;

        public CaptchaController(ILogger<CaptchaController> logger, IWebHostEnvironment env)
        {
            this._logger = logger;
            this._env = env;
        }

        public IActionResult Image()
        {
            var code = string.Empty;
            var builder = new StringBuilder();
            builder.Append(code);
            for (int i = 0; i < 4; i++)
            {
                var random = new byte[1];
                using var generator = RandomNumberGenerator.Create();
                generator.GetBytes(random);
                builder.Append(new Random(Convert.ToInt32(random[0])).Next(0, 9));
            }
            code = builder.ToString();
            this.HttpContext.Session.Set<ImageCaptchaModel>(ImageCaptchaModel.Key, new ImageCaptchaModel
            {
                Captcha = code,
                ExpireDateUtc = DateTime.UtcNow.AddSeconds(300)
            });
            using var helper = new CaptchaHelper(this._env);
            return File(helper.GetCaptcha(code), "image/jpeg");
        }
    }
}