c# - 以相同的 ConfigureServices 方法访问在 asp.net core 的 startup.cs 文件中的 ConfigureServices 中创建的单例

Question

所以我一直在尝试以 JWT 分发的形式设置一个带有 token 身份验证的小型测试 api， token 分发部分按预期工作。

然而，由于我想让我的 JWT 服务的方法更通用，以允许对 token 进行不同类型的签名(因为我更喜欢私钥/公钥对)，所以我尝试在 appsettings 文件中设置更多选项这将决定 token 的生成方式，我开始使用依赖注入(inject)加载这些设置，直到现在我几乎没有接触过。

所以当我想将我设置为单例的那些配置类(到目前为止我已经通读过的大多数指南都这样做了，所以我认为它有点正确)并在ConfigureServices 他们添加的方法，这样我就可以使用我认为应该设置的参数，因为我通过获取 appsettings 文件的一部分在上面配置了几行。

但是，一旦我尝试访问它们，我就什么也得不到了，而是留下了空值。

启动.cs

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        //the token config takes values from the appsettings.json file
        var tokenConf = Configuration.GetSection("TokenConfiguration");
        services.Configure<TokenConfiguration>(tokenConf);

        //the signing credentials are assigned in the JwtTokenService constructor
        var signingConf = new SigningConfiguration();
        services.AddSingleton<SigningConfiguration>(signingConf);
        //my token service
        services.AddSingleton<IJwtTokenService, JwtTokenService>();

        //i try to get hold of the actual values to use later on
        var provider = services.BuildServiceProvider();
        TokenConfiguration tc = provider.GetService<TokenConfiguration>();
        SigningConfiguration sc = provider.GetService<SigningConfiguration>();

        //i wanna use the values in here when i set the parameters for my authentication
        services.AddAuthentication(x =>
        {
            x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
            x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        }).AddJwtBearer(x =>
        {
            x.Events = new JwtBearerEvents
            {
                OnTokenValidated = context =>
                {
                    return Task.CompletedTask;
                }
            };

            x.RequireHttpsMetadata = false;
            x.SaveToken = true;
            x.TokenValidationParameters = new TokenValidationParameters
            {
                ValidateIssuerSigningKey = true,
                ValidateIssuer = true,
                ValidateAudience = true,
                ValidateLifetime = true,
                //values used here since i specify issuer, audience and what kind of key to use in the settings
                //the key & credentials differ based on a bool in the settings file and will either be a symmetric or asymmetric key
                ValidIssuer = tc.Issuer,
                ValidAudience = tc.Audience,
                IssuerSigningKey = sc.Key
            };
        });

        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseMvc();
    }
}

JwtTokenService.cs(IJwtTokenService只有CreateToken方法在这里实现)

public class JwtTokenService : IJwtTokenService
{
    private TokenConfiguration tokenConf;
    public SigningConfiguration signingConf;

    public JwtTokenService(IOptions<TokenConfiguration> tc) {
        tokenConf = tc.Value;
        signingConf = new SigningConfiguration();

        //if the asymmetric bool is set to true, assign a new rsa keypair to the signing configuration
        //otherwise, use a symmetric key with a hmac hash
        if (tc.Value.AsymmetricKey)
        {
            using (var provider = new RSACryptoServiceProvider(2048))
            {
                signingConf.Key = new RsaSecurityKey(provider.ExportParameters(true));
            }

            signingConf.SigningCredentials =
                new SigningCredentials(
                    signingConf.Key,
                    SecurityAlgorithms.RsaSha256);
        }
        else {
            signingConf.Key = 
                new SymmetricSecurityKey(
                    Encoding.UTF8.GetBytes(tc.Value.HmacSecret));

            signingConf.SigningCredentials = 
                new SigningCredentials(
                    signingConf.Key, 
                    SecurityAlgorithms.HmacSha512);
        }
    }

    /// <summary>
    /// Creates a token based on the running configuration
    /// </summary>
    public string CreateToken(List<Claim> claims)
    {
        var token = new JwtSecurityToken(
            issuer: tokenConf.Issuer,
            audience: tokenConf.Audience,
            claims: claims,
            expires: DateTime.UtcNow.AddMinutes(tokenConf.Minutes),
            signingCredentials: signingConf.SigningCredentials
            );

        return new JwtSecurityTokenHandler().WriteToken(token);
    }
}

token 配置.cs

public class TokenConfiguration
{
    public string Audience { get; set; }
    public string Issuer { get; set; }
    public int Minutes { get; set; }
    public bool AsymmetricKey { get; set; }
    public string HmacSecret { get; set; }
}

SigningConfiguration.cs

public class SigningConfiguration
{
    public SecurityKey Key { get; set; }
    public SigningCredentials SigningCredentials { get; set; }
}

应用设置.json

"TokenConfiguration": {
"Audience": "ExampleAudience",
"Issuer": "ExampleIssuer",
"Minutes": 30,
"AsymmetricKey": true,
"HmacSecret": "example-secret-top-secret-secret-is_secret"

(该项目在 asp.net core 2.1 中运行以防万一)

我是 DI 的新手，找不到很多用例与我相同的示例，而且大多数此类案例涉及实际服务，而不是通过 DI 添加“配置”类。

可能有更好的方法来做到这一点，我可能只是愚蠢，因为没有注意到或不知道要谷歌搜索什么才能得到正确的答案，很可能会观看/阅读一些关于 DI 的内容在此之后不管。

任何意见或想法都将不胜感激，因为我对 asp.net core 和整个流程还是陌生的。

作为关于私钥生成的一个小问题，在我的例子中，最好将生成的 key 对存储在 keystore 中，或者将其存储在内存中，或者通过 openSSL 之类的东西生成它们并从中读取在启动时是最佳选择吗？

Answer 1

您正在请求 TokenConfiguration而不是 IOptions<TokenConfiguration>来自服务提供商。更改此行

   TokenConfiguration tc = provider.GetService<TokenConfiguration>();
   SigningConfiguration sc = provider.GetService<SigningConfiguration>(); 

与

    IOptions<TokenConfiguration> tc = provider.GetService<IOptions<TokenConfiguration>>();
    IOptions<SigningConfiguration> sc = provider.GetService<IOptions<SigningConfiguration>>();

然后使用 tc.Value 访问选项.

建筑 ServiceProvider在ConfigureServices这不是一个好主意，我会通过 Configuration["TokenConfiguration:Audience"] 直接从配置中获取我需要的任何地方 ConfigureServices .