前言：本文将会结合asp.net core 认证源码来分析起认证的原理与流程。asp.net core版本2.2
对于大部分使用asp.net core开发的人来说。
下面这几行代码应该很熟悉了。
services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme) .AddJwtBearer(options => { options.RequireHttpsMetadata = false; options.Audience = "sp_api"; options.Authority = "http://localhost:5001"; options.SaveToken = true; })
app.UseAuthentication();
废话不多说。直接看 app.UseAuthentication()的源码
public class AuthenticationMiddleware { private readonly RequestDelegate _next; public AuthenticationMiddleware(RequestDelegate next, IAuthenticationSchemeProvider schemes) { if (next == null) { throw new ArgumentNullException(nameof(next)); } if (schemes == null) { throw new ArgumentNullException(nameof(schemes)); } _next = next; Schemes = schemes; } public IAuthenticationSchemeProvider Schemes { get; set; } 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); }
现在来看看var defaultAuthenticate = await Schemes.GetDefaultAuthenticateSchemeAsync(); 干了什么。
在这之前。我们更应该要知道上面代码中 public IAuthenticationSchemeProvider Schemes { get; set; } ，假如脑海中对这个IAuthenticationSchemeProvider类型的来源，有个清晰认识，对后面的理解会有很大的帮助
现在来揭秘IAuthenticationSchemeProvider 是从哪里来添加到ioc的。
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); }
红色代码内部逻辑中就把IAuthenticationSchemeProvider添加到了IOC中。先来看看services.AddAuthenticationCore()的源码，这个源码的所在的解决方案的仓库地址是https://github.com/aspnet/HttpAbstractions，这个仓库目前已不再维护，其代码都转移到了asp.net core 仓库 。
下面为services.AddAuthenticationCore()的源码
public static class AuthenticationCoreServiceCollectionExtensions { /// <summary> /// Add core authentication services needed for <see cref="IAuthenticationService"/>. /// </summary> /// <param name="services">The <see cref="IServiceCollection"/>.</param> /// <returns>The service collection.</returns> 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; } /// <summary> /// Add core authentication services needed for <see cref="IAuthenticationService"/>. /// </summary> /// <param name="services">The <see cref="IServiceCollection"/>.</param> /// <param name="configureOptions">Used to configure the <see cref="AuthenticationOptions"/>.</param> /// <returns>The service collection.</returns> public static IServiceCollection AddAuthenticationCore(this IServiceCollection services, Action<AuthenticationOptions> configureOptions) { if (services == null) { throw new ArgumentNullException(nameof(services)); } if (configureOptions == null) { throw new ArgumentNullException(nameof(configureOptions)); } services.AddAuthenticationCore(); services.Configure(configureOptions); return services; } }
完全就可以看待添加了一个全局单例的IAuthenticationSchemeProvider对象。现在让我们回到MiddleWare中探究Schemes.GetDefaultAuthenticateSchemeAsync(); 干了什么。光看方法的名字都能猜出就是获取的默认的认证策略。
进入到IAuthenticationSchemeProvider 实现的源码中，按我的经验，来看先不急看GetDefaultAuthenticateSchemeAsync()里面的内部逻辑。必须的看下IAuthenticationSchemeProvider实现类的构造函数。它的实现类是AuthenticationSchemeProvider。
先看看AuthenticationSchemeProvider的构造方法
public class AuthenticationSchemeProvider : IAuthenticationSchemeProvider { /// <summary> /// Creates an instance of <see cref="AuthenticationSchemeProvider"/> /// using the specified <paramref name="options"/>, /// </summary> /// <param name="options">The <see cref="AuthenticationOptions"/> options.</param> public AuthenticationSchemeProvider(IOptions<AuthenticationOptions> options) : this(options, new Dictionary<string, AuthenticationScheme>(StringComparer.Ordinal)) { } /// <summary> /// Creates an instance of <see cref="AuthenticationSchemeProvider"/> /// using the specified <paramref name="options"/> and <paramref name="schemes"/>. /// </summary> /// <param name="options">The <see cref="AuthenticationOptions"/> options.</param> /// <param name="schemes">The dictionary used to store authentication schemes.</param> protected AuthenticationSchemeProvider(IOptions<AuthenticationOptions> options, IDictionary<string, AuthenticationScheme> schemes) { _options = options.Value; _schemes = schemes ?? throw new ArgumentNullException(nameof(schemes)); _requestHandlers = new List<AuthenticationScheme>(); foreach (var builder in _options.Schemes) { var scheme = builder.Build(); AddScheme(scheme); } } private readonly AuthenticationOptions _options; private readonly object _lock = new object(); private readonly IDictionary<string, AuthenticationScheme> _schemes; private readonly List<AuthenticationScheme> _requestHandlers;
不难看出，上面的构造方法需要一个IOptions<AuthenticationOptions> 类型。没有这个类型，而这个类型是从哪里的了？
答：不知到各位是否记得addJwtBearer这个方法，再找个方法里面就注入了AuthenticationOptions找个类型。
看源码把
public static class JwtBearerExtensions { public static AuthenticationBuilder AddJwtBearer(this AuthenticationBuilder builder) => builder.AddJwtBearer(JwtBearerDefaults.AuthenticationScheme, _ => { }); public static AuthenticationBuilder AddJwtBearer(this AuthenticationBuilder builder, Action<JwtBearerOptions> configureOptions) => builder.AddJwtBearer(JwtBearerDefaults.AuthenticationScheme, configureOptions); public static AuthenticationBuilder AddJwtBearer(this AuthenticationBuilder builder, string authenticationScheme, Action<JwtBearerOptions> configureOptions) => builder.AddJwtBearer(authenticationScheme, displayName: null, configureOptions: configureOptions); public static AuthenticationBuilder AddJwtBearer(this AuthenticationBuilder builder, string authenticationScheme, string displayName, Action<JwtBearerOptions> configureOptions) { builder.Services.TryAddEnumerable(ServiceDescriptor.Singleton<IPostConfigureOptions<JwtBearerOptions>, JwtBearerPostConfigureOptions>()); return builder.AddScheme<JwtBearerOptions, JwtBearerHandler>(authenticationScheme, displayName, configureOptions); } }
不难通过上述代码看出它是及一个基于AuthenticationBuilder的扩展方法，而注入AuthenticationOptions的关键就在于 builder.AddScheme<JwtBearerOptions, JwtBearerHandler>(authenticationScheme, displayName, configureOptions); 这行代码，按下F12看下源码
public virtual AuthenticationBuilder AddScheme<TOptions, THandler>(string authenticationScheme, string displayName, Action<TOptions> configureOptions) where TOptions : AuthenticationSchemeOptions, new() where THandler : AuthenticationHandler<TOptions> => AddSchemeHelper<TOptions, THandler>(authenticationScheme, displayName, configureOptions); private AuthenticationBuilder AddSchemeHelper<TOptions, THandler>(string authenticationScheme, string displayName, Action<TOptions> configureOptions) where TOptions : class, new() where THandler : class, IAuthenticationHandler { Services.Configure<AuthenticationOptions>(o => { o.AddScheme(authenticationScheme, scheme => { scheme.HandlerType = typeof(THandler); scheme.DisplayName = displayName; }); }); if (configureOptions != null) { Services.Configure(authenticationScheme, configureOptions); } Services.AddTransient<THandler>(); return this; }
照旧还是分为2个方法来进行调用，其重点就是AddSchemeHelper找个方法。其里面配置AuthenticationOptions类型。现在我们已经知道了IAuthenticationSchemeProvider何使注入的。还由AuthenticationSchemeProvider构造方法中IOptions<AuthenticationOptions> options是何使配置的，这样我们就对于认证有了一个初步的认识。现在可以知道对于认证中间件，必须要有一个IAuthenticationSchemeProvider 类型。而这个IAuthenticationSchemeProvider的实现类的构造函数必须要由IOptions<AuthenticationOptions> options，没有这两个类型，认证中间件应该是不会工作的。
回到认证中间件中。继续看var defaultAuthenticate = await Schemes.GetDefaultAuthenticateSchemeAsync();这句代码，源码如下
public virtual Task<AuthenticationScheme> GetDefaultAuthenticateSchemeAsync() => _options.DefaultAuthenticateScheme != null ? GetSchemeAsync(_options.DefaultAuthenticateScheme) : GetDefaultSchemeAsync(); public virtual Task<AuthenticationScheme> GetSchemeAsync(string name) => Task.FromResult(_schemes.ContainsKey(name) ? _schemes[name] : null); private Task<AuthenticationScheme> GetDefaultSchemeAsync() => _options.DefaultScheme != null ? GetSchemeAsync(_options.DefaultScheme)
: Task.FromResult<AuthenticationScheme>(null);
让我们先验证下方法1的三元表达式，应该执行那边呢？通过前面的代码我们知道AuthenticationOptions是在AuthenticationBuilder类型的AddSchemeHelper方法里面进行配置的。经过我的调试，发现方法1会走右边。其实最终还是从一个字典中取到了默认的AuthenticationScheme对象。到这里中间件的里面var defaultAuthenticate = await Schemes.GetDefaultAuthenticateSchemeAsync();代码就完了。最终就那到了AuthenticationScheme的对象。
下面来看看 中间件中var result = await context.AuthenticateAsync(defaultAuthenticate.Name);这句代码干了什么。按下F12发现是一个扩展方法，还是到HttpAbstractions解决方案里面找下源码
源码如下
public static Task<AuthenticateResult> AuthenticateAsync(this HttpContext context, string scheme) => context.RequestServices.GetRequiredService<IAuthenticationService>().AuthenticateAsync(context, scheme);
通过上面的方法，发现是通过IAuthenticationService的AuthenticateAsync() 来进行认证的。那么现在IAuthenticationService这个类是干什么 呢？
下面为IAuthenticationService的定义
public interface IAuthenticationService { Task<AuthenticateResult> AuthenticateAsync(HttpContext context, string scheme); Task ChallengeAsync(HttpContext context, string scheme, AuthenticationProperties properties); Task ForbidAsync(HttpContext context, string scheme, AuthenticationProperties properties); Task SignInAsync(HttpContext context, string scheme, ClaimsPrincipal principal, AuthenticationProperties properties); Task SignOutAsync(HttpContext context, string scheme, AuthenticationProperties properties); }
IAuthenticationService的AuthenticateAsync()方法的实现源码
public class AuthenticationService : IAuthenticationService { /// <summary> /// Constructor. /// </summary> /// <param name="schemes">The <see cref="IAuthenticationSchemeProvider"/>.</param> /// <param name="handlers">The <see cref="IAuthenticationRequestHandler"/>.</param> /// <param name="transform">The <see cref="IClaimsTransformation"/>.</param> public AuthenticationService(IAuthenticationSchemeProvider schemes, IAuthenticationHandlerProvider handlers, IClaimsTransformation transform) { Schemes = schemes; Handlers = handlers; Transform = transform; }
{
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.");
}
}
if (handler == null)
{
throw await CreateMissingHandlerException(scheme);
}
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;
}
通过构造方法可以看到这个类的构造方法需要IAuthenticationSchemeProvider类型和IAuthenticationHandlerProvider 类型，前面已经了解了IAuthenticationSchemeProvider是干什么的，取到配置的授权策略的名称，那现在IAuthenticationHandlerProvider 是干什么的，看名字感觉应该是取到具体授权策略的handler.废话补多少，看IAuthenticationHandlerProvider 接口定义把
public interface IAuthenticationHandlerProvider { /// <summary> /// Returns the handler instance that will be used. /// </summary> /// <param name="context">The context.</param> /// <param name="authenticationScheme">The name of the authentication scheme being handled.</param> /// <returns>The handler instance.</returns> Task<IAuthenticationHandler> GetHandlerAsync(HttpContext context, string authenticationScheme); }
通过上面的源码，跟我猜想的不错，果然就是取得具体的授权策略
现在我就可以知道AuthenticationService是对IAuthenticationSchemeProvider和IAuthenticationHandlerProvider封装。最终调用IAuthentionHandel的AuthenticateAsync()方法进行认证。最终返回一个AuthenticateResult对象。
总结，对于asp.net core的认证来水，他需要下面这几个对象
AuthenticationBuilder 扶着对认证策略的配置与初始话
IAuthenticationHandlerProvider AuthenticationHandlerProvider 负责获取配置了的认证策略的名称
IAuthenticationSchemeProvider AuthenticationSchemeProvider 负责获取具体认证策略的handle
IAuthenticationService AuthenticationService 实对上面两个Provider 的封装，来提供一个具体处理认证的入口
IAuthenticationHandler 和的实现类，是以哦那个来处理具体的认证的，对不同认证策略的出来，全是依靠的它的AuthenticateAsync()方法。
AuthenticateResult 最终的认证结果。
哎写的太垃圾了。