AspNetCore3.1_Secutiry源码解析_2_Authentication_核心对象

---

title: "AspNetCore3.1_Secutiry源码解析_2_Authentication_核心流程"
date: 2020-03-18T21:19:15+08:00
draft: false
---

系列文章目录

• AspNetCore3.1_Secutiry源码解析_1_目录
• AspNetCore3.1_Secutiry源码解析_2_Authentication_核心项目
• AspNetCore3.1_Secutiry源码解析_3_Authentication_Cookies
• AspNetCore3.1_Secutiry源码解析_4_Authentication_JwtBear
• AspNetCore3.1_Secutiry源码解析_5_Authentication_OAuth
• AspNetCore3.1_Secutiry源码解析_6_Authentication_OpenIdConnect
• AspNetCore3.1_Secutiry源码解析_7_Authentication_其余
• AspNetCore3.1_Secutiry源码解析_8_Authorization_核心项目
• AspNetCore3.1_Secutiry源码解析_9_Authorization_Policy

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。

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) }

经过AuthenticateAsync方法源代码能够看到，AuthenticateService只是作了控制器的角色，校验schema，根据schema获取handler，主要的认证逻辑是由handler处理。其余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，不会作任何操做。若是须要对Claims作一些处理，实现IClaimsTransformation并覆盖注入就能够了。

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，这个接口能够根据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的操做方法。

AuthenticationScheme主要有三个属性，经过HandlerType与handler创建了关联。

classDiagram class AuthenticationScheme{ Name DisplayName HandlerType }

认证流程

graph TD A(AuthenticationOptions定义五个认证动做的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)

其余

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，若是handler不为空的话，则执行handler的HandleRequestAsync方法。IAuthenticationRequestHandler一般在远程认证（如：OAuth, OIDC等）中使用。

若是没有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);
    }