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。
我要评论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;
}
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。
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。
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(精华)2020年7月21日 ASP.NET Core 容器伪属性注入
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