ediwang / edi.captcha.aspnetcore

The Captcha module used in my blog

Edi.Captcha.AspNetCore

The Captcha module used in my blog

Usage

0. Install from NuGet

NuGet Package Manager

Install-Package Edi.Captcha

or .NET CLI

dotnet add package Edi.Captcha

1. Register in DI

services.AddSession(options =>
{
    options.IdleTimeout = TimeSpan.FromMinutes(20);
    options.Cookie.HttpOnly = true;
});

services.AddSessionBasedCaptcha();

// Don't forget to add this line in your `Configure` method.
 app.UseSession();

or you can customize the options

services.AddSessionBasedCaptcha(option =>
{
    option.Letters = "2346789ABCDEFGHJKLMNPRTUVWXYZ";
    option.SessionName = "CaptchaCode";
    option.CodeLength = 4;
});

2. Generate Image

Using MVC Controller

private readonly ISessionBasedCaptcha _captcha;

public SomeController(ISessionBasedCaptcha captcha)
{
    _captcha = captcha;
}

[Route("get-captcha-image")]
public IActionResult GetCaptchaImage()
{
    var s = _captcha.GenerateCaptchaImageFileStream(
        HttpContext.Session,
        100,
        36
    );
    return s;
}

Using Middleware

app.UseSession().UseCaptchaImage(options =>
{
    options.RequestPath = "/captcha-image";
    options.ImageHeight = 36;
    options.ImageWidth = 100;
});

3. Add CaptchaCode Property to Model

[Required]
[StringLength(4)]
public string CaptchaCode { get; set; }

5. View

<div class="col">
    <div class="input-group">
        <div class="input-group-prepend">
            <img id="img-captcha" src="~/captcha-image" />
        </div>
        <input type="text" 
               asp-for="CommentPostModel.CaptchaCode" 
               class="form-control" 
               placeholder="Captcha Code" 
               autocomplete="off" 
               minlength="4"
               maxlength="4" />
    </div>
    <span asp-validation-for="CommentPostModel.CaptchaCode" class="text-danger"></span>
</div>

6. Validate Input

_captcha.ValidateCaptchaCode(model.CommentPostModel.CaptchaCode, HttpContext.Session)

To make your code look more cool, you can also write an Action Filter like this:

public class ValidateCaptcha : ActionFilterAttribute
{
    private readonly ISessionBasedCaptcha _captcha;

    public ValidateCaptcha(ISessionBasedCaptcha captcha)
    {
        _captcha = captcha;
    }

    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var captchaedModel =
            context.ActionArguments.Where(p => p.Value is ICaptchable)
                                   .Select(x => x.Value as ICaptchable)
                                   .FirstOrDefault();

        if (null == captchaedModel)
        {
            context.ModelState.AddModelError(nameof(captchaedModel.CaptchaCode), "Captcha Code is required");
            context.Result = new BadRequestObjectResult(context.ModelState);
        }
        else
        {
            if (!_captcha.Validate(captchaedModel.CaptchaCode, context.HttpContext.Session))
            {
                context.ModelState.AddModelError(nameof(captchaedModel.CaptchaCode), "Wrong Captcha Code");
                context.Result = new ConflictObjectResult(context.ModelState);
            }
            else
            {
                base.OnActionExecuting(context);
            }
        }
    }
}

and then

services.AddScoped<ValidateCaptcha>();

and then

public class YourModelWithCaptchaCode : ICaptchable
{
    public string YourProperty { get; set; }

    [Required]
    [StringLength(4)]
    public string CaptchaCode { get; set; }
}

[ServiceFilter(typeof(ValidateCaptcha))]
public async Task<IActionResult> SomeAction(YourModelWithCaptchaCode model)
{
    // ....
}

Refer to https://edi.wang/post/2018/10/13/generate-captcha-code-aspnet-core

免责申明

此项目(Edi.Captcha.AspNetCore)及其配套组件均为免费开源的产品，仅用于学习交流，并且不直接向**提供服务，**用户请于下载后立即删除。

任何**境内的组织及个人不得使用此项目(Edi.Captcha.AspNetCore)及其配套组件构建任何形式的面向**境内用户的网站或服务。

不可用于任何违反中华人民共和国(含**省)或使用者所在地区法律法规的用途。

因为作者即本人仅完成代码的开发和开源活动(开源即任何人都可以下载使用)，从未参与用户的任何运营和盈利活动。

且不知晓用户后续将程序源代码用于何种用途，故用户使用过程中所带来的任何法律责任即由用户自己承担。

《开源软件有漏洞，作者需要负责吗？是的！》

edi.captcha.aspnetcore's Issues

In a cluster environment, there will be problems using session. Have you considered saving the captcha in redis.

In a cluster environment, there will be problems using session. Have you considered saving the captcha in redis.

Characters outside of image

Hi,
I've got something like this on attached image. The characters are out of an image rectangle. The version of component is 3.13.1.

The code is like that:
var s = _captcha.GenerateCaptchaImageFileStream( HttpContext.Session, 330, 100 ); return s;

Is it a bug or wrong implementation?

Michael K.

Validation problem on server

Hello,

I added your captcha to my project. It works perfect on localhost.
But it' not working on server (iis).
Following code always return false;

!_captcha.Validate(captchaedModel.CaptchaCode, context.HttpContext.Session)
How can I fix this?
Best

在netcore2.2/centos7下使用有什么注意事项吗？

我在win10下面运行我的asp.net core 2.2 mvc网站可以正常使用验证码，我部署到centos7上以后获取验证码接口就报错了，请问下有什么注意事项吗？ 万分感谢~

It is recommended to add case-ignoring

It is suggested to add case-ignoring judgment when making verification code judgment here.
like this:
var isValid = userInputCaptcha.Equals(HttpContext.Session.GetString(CaptchaCodeSessionName), StringComparison.OrdinalIgnoreCase);

The sample app can not run in docker container

I have an issue when I deploy the sample app in a ubuntu docker container, the exception is can not find 'libdl'.