@gvrs/nestjs-hcaptcha

A NestJS module for adding hCaptcha validation

Installation

npm i @gvrs/nestjs-hcaptcha

Usage

First, provide the options in the root AppModule:

@Module({
  imports: [
    HcaptchaModule.forRoot({
      secret: "YOUR_HCAPTCHA_SECRET",
    }),
  ],
})
export class AppModule {}

Afterward, import the HcaptchaModule in the module where you need to use captcha validation:

@Module({
  imports: [HcaptchaModule],
  controllers: [UsersController],
})
export class UsersModule {}

Finally, decorate the controller method with @VerifyCaptcha():

@Controller("users")
class UsersController {
  @Post("register")
  @VerifyCaptcha()
  register() {}
}

By default, the hCaptcha token will be extracted from the h-captcha-response request body field

Setting the sitekey you expect to see

Provide the sitekey option in the root HcaptchaModule:

@Module({
  imports: [
    HcaptchaModule.forRoot({
      secret: "YOUR_HCAPTCHA_SECRET",
      sitekey: "YOUR_SITEKEY",
    }),
  ],
})
export class AppModule {}

Customizing the captcha data extraction

If you want to customize the retrieval of the hCaptcha token and/or the user's IP address, provide an implementation of getCaptchaData in the root HcaptchaModule:

@Module({
  imports: [
    HcaptchaModule.forRoot({
      secret: "YOUR_HCAPTCHA_SECRET",
      getCaptchaData: (ctx) => {
        const request = ctx.switchToHttp().getRequest();

        const token = request.body["token"];
        const remoteip = request.headers["x-forwarded-for"];

        return { token, remoteip };
      },
    }),
  ],
})
export class AppModule {}

Customizing the error response

By default, when the captcha is invalid, or cannot be validated, a 403 error will be sent to the client. To customize that response, use an exception filter:

@Catch(HcaptchaException)
class HcaptchaExceptionFilter implements ExceptionFilter {
  catch(exception: HcaptchaException, host: ArgumentsHost) {
    const ctx = host.switchToHttp();
    const response = ctx.getResponse();
    const status = 400;

    response.status(status).json({
      statusCode: status,
      message: "Invalid captcha",
    });
  }
}

Imperative captcha verification

If you don't want to, or cannot use the @VerifyCaptha() decorator or the HcaptchaGuard, you can verify the captcha by using the HcaptchaService:

@Controller("users")
class UsersController {
  constructor(private readonly hcaptchaService: HcaptchaService) {}

  @Post("register")
  async register(@Req() request: Request) {
    try {
      const token = request.body["h-captcha-response"];

      // returns the hCaptcha JSON response, or throws a HcaptchaException
      const verifyResponse = await this.hcaptchaService.verifyCaptcha(token);
    } catch {
      throw new BadRequestException();
    }
  }
}

License

MIT © Aliaksandr Haurusiou.