AspNetCore3.1_Secutiry源码解析_2_Authentication_核心对象

文章目录

依赖注入

框架提供了三个依赖注入重载方法。

//注入认证服务

services.AddAuthentication();

//注入认证服务并制定默认架构名

services.AddAuthentication("Cookies");

//注入认证服务并设置配置项

services.AddAuthentication(config =>

{

});

看看注入代码

public static AuthenticationBuilder AddAuthentication(this IServiceCollection services)

    {

        if (services == null)

        {

            throw new ArgumentNullException(nameof(services));

        }

        services.AddAuthenticationCore();

        services.AddDataProtection();

        services.AddWebEncoders();

        services.TryAddSingleton<ISystemClock, SystemClock>();

        return new AuthenticationBuilder(services);

    }

AddAuthenticationCore注入了认证服务的核心对象。这个方法在Authentication.Core项目，这个项目定义了认证服务的核心对象，在Authentication.Abstractions项目中定义了核心接口。

AspNetCore3.1_Secutiry源码解析_2_Authentication_核心对象

AddAuthenticationCore方法注入了IAuthenticationService，IClaimsTransformation，IAuthenticationHandlerProvider，IAuthenticationSchemeProvider

public static IServiceCollection AddAuthenticationCore(this IServiceCollection services)

{

    if (services == null)

    {

        throw new ArgumentNullException(nameof(services));

    }

    services.TryAddScoped<IAuthenticationService, AuthenticationService>();

    services.TryAddSingleton<IClaimsTransformation, NoopClaimsTransformation>(); // Can be replaced with scoped ones that use DbContext

    services.TryAddScoped<IAuthenticationHandlerProvider, AuthenticationHandlerProvider>();

    services.TryAddSingleton<IAuthenticationSchemeProvider, AuthenticationSchemeProvider>();

    return services;

}

IAuthenticationService

认证服务，定义了五个方法

AuthenticateAsync: 认证
ChallengeAsync：挑战，校验认证
ForbidAsync：禁止认证
SignInAsync：登入
SignOutAsync：登出

classDiagram
class IAuthenticationService{
+AuthenticateAsync(HttpContext context, string scheme)
+ChallengeAsync(HttpContext context, string scheme, AuthenticationProperties properties)
+ForbidAsync(HttpContext context, string scheme, AuthenticationProperties properties)
+SignInAsync(HttpContext context, string scheme, ClaimsPrincipal principal, AuthenticationProperties properties)
+SignOutAsync(HttpContext context, string scheme, AuthenticationProperties properties)
}

通过AuthenticateAsync方法源代码可以看到，AuthenticateService只是做了控制器的角色，校验schema，根据schema获取handler，主要的认证逻辑是由handler处理。其他的方法基本也是这样的逻辑。

 public virtual async Task<AuthenticateResult> AuthenticateAsync(HttpContext context, string scheme)

{

    if (scheme == null)

    {

        var defaultScheme = await Schemes.GetDefaultAuthenticateSchemeAsync();

        scheme = defaultScheme?.Name;

        if (scheme == null)

        {

            throw new InvalidOperationException($"No authenticationScheme was specified, and there was no DefaultAuthenticateScheme found. The default schemes can be set using either AddAuthentication(string defaultScheme) or AddAuthentication(Action<AuthenticationOptions> configureOptions).");

        }

    }

    var handler = await Handlers.GetHandlerAsync(context, scheme);

    if (handler == null)

    {

        throw await CreateMissingHandlerException(scheme);

    }

    var result = await handler.AuthenticateAsync();

    if (result != null && result.Succeeded)

    {

        var transformed = await Transform.TransformAsync(result.Principal);

        return AuthenticateResult.Success(new AuthenticationTicket(transformed, result.Properties, result.Ticket.AuthenticationScheme));

    }

    return result;

}

IClaimsTransformation

classDiagram
class IClaimsTransformation{
+TransformAsync(ClaimsPrincipal principal)
}

该接口只有一个方法，用于转换Claims。默认注入的NoopClaimsTransformation，不会做任何操作。如果需要对Claims做一些处理，实现IClaimsTransformation并覆盖注入就可以了。

public class NoopClaimsTransformation : IClaimsTransformation

{

    /// <summary>

    /// Returns the principal unchanged.

    /// </summary>

    /// <param name="principal">The user.</param>

    /// <returns>The principal unchanged.</returns>

    public virtual Task<ClaimsPrincipal> TransformAsync(ClaimsPrincipal principal)

    {

        return Task.FromResult(principal);

    }

}

IAuthenticationHandlerProvider

classDiagram
class IAuthenticationHandlerProvider{
+GetHandlerAsync(HttpContext context, string authenticationScheme)
}

上面提到过handler处理了主要的认证业务逻辑，这个接口可以根据schema获取handler。

IAuthenticationSchemeProvider

classDiagram
class IAuthenticationSchemeProvider{
+GetAllSchemesAsync()
+GetSchemeAsync(string name)
+GetDefaultAuthenticateSchemeAsync()
+GetDefaultChallengeSchemeAsync()
+GetDefaultForbidSchemeAsync()
+GetDefaultSignInSchemeAsync()
+GetDefaultSignOutSchemeAsync()
+AddScheme(AuthenticationScheme scheme)
+RemoveScheme(string name)
+GetRequestHandlerSchemesAsync()
}

该接口主要定义了一些schema的操作方法。

AuthenticationScheme主要有三个属性，通过HandlerType与handler建立了关联。

classDiagram
class AuthenticationScheme{
Name
DisplayName
HandlerType
}

认证流程

graph TD
A(AuthenticationOptions定义五个认证动作的Schema)
A --> B1(Authenticate)
A --> B2(Challenge)
A --> B3(Forbid)
A --> B4(SignIn)
A --> B5(SingOut)
C(IAuthenticationSchemeProvider获取Schema)
B1 --> C
B2 --> C
B3 --> C
B4 --> C
B5 --> C
C --> D(IAuthenticationHandlerProvider获取Schema对应的Handler)
D --> E(处理请求)

其他

除了核心对象，还注入了用于数据保护和解码的辅助对象

services.AddDataProtection();

services.AddWebEncoders();

Authentication中间件

中间件会优先在容器中找IAuthenticationRequestHandler的实现，如果handler不为空的话，则执行handler的HandleRequestAsync方法。IAuthenticationRequestHandler通常在远程认证（如：OAuth, OIDC等）中使用。

如果没有IAuthenticationRequestHandler的实现，则会找默认schema，执行默认schema对应handler的AuthenticationAsync方法，认证成功后，给HttpContext的User对象赋值。

public async Task Invoke(HttpContext context)

    {

        context.Features.Set<IAuthenticationFeature>(new AuthenticationFeature

        {

            OriginalPath = context.Request.Path,

            OriginalPathBase = context.Request.PathBase

        });

        // Give any IAuthenticationRequestHandler schemes a chance to handle the request

        var handlers = context.RequestServices.GetRequiredService<IAuthenticationHandlerProvider>();

        foreach (var scheme in await Schemes.GetRequestHandlerSchemesAsync())

        {

            var handler = await handlers.GetHandlerAsync(context, scheme.Name) as IAuthenticationRequestHandler;

            if (handler != null && await handler.HandleRequestAsync())

            {

                return;

            }

        }

        var defaultAuthenticate = await Schemes.GetDefaultAuthenticateSchemeAsync();

        if (defaultAuthenticate != null)

        {

            var result = await context.AuthenticateAsync(defaultAuthenticate.Name);

            if (result?.Principal != null)

            {

                context.User = result.Principal;

            }

        }

        await _next(context);

    }

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