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小編給大家分享一下ASP.NET中Core Authentication進行認證的流程，希望大家閱讀完這篇文章后大所收獲，下面讓我們一起去探討吧！
追本溯源，從使用開始
首先看一下我們通常是如何使用微軟自帶的認證，一般在Startup里面配置我們所需的依賴認證服務，這里通過JWT的認證方式講解
public void ConfigureServices(IServiceCollection services)
{
services.AddAuthentication(authOpt =>
{
authOpt.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
authOpt.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
})
.AddJwtBearer(o =>
{
o.TokenValidationParameters = new TokenValidationParameters
{
//配置自己所要驗證的參數
};
});
}我們來看一下源碼AddAuthentication主要做了什么
public static class AuthenticationServiceCollectionExtensions
{
public static AuthenticationBuilder AddAuthentication( this IServiceCollection services, Action<AuthenticationOptions> configureOptions)
{
if (services == null)
throw new ArgumentNullException(nameof (services));
if (configureOptions == null)
throw new ArgumentNullException(nameof (configureOptions));
AuthenticationBuilder authenticationBuilder = services.AddAuthentication();
services.Configure<AuthenticationOptions>(configureOptions);
return authenticationBuilder;
}
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);
}
public static AuthenticationBuilder AddAuthentication(
this IServiceCollection services,
string defaultScheme)
{
return services.AddAuthentication((Action<AuthenticationOptions>) (o => o.DefaultScheme = defaultScheme));
}
.....
}ConfigureServices方法基本都是服務的注冊，基于微軟的風格，這里的AddAuthenticationCore肯定是我們的認證服務注冊方法，來看一下
public static class AuthenticationCoreServiceCollectionExtensions
{
/// <summary>
/// Add core authentication services needed for <see cref="T:Microsoft.AspNetCore.Authentication.IAuthenticationService" />.
/// </summary>
public static IServiceCollection AddAuthenticationCore(
this IServiceCollection services)
{
if (services == null)
throw new ArgumentNullException(nameof (services));
services.TryAddScoped<IAuthenticationService, AuthenticationService>();
services.TryAddSingleton<IClaimsTransformation, NoopClaimsTransformation>();
services.TryAddScoped<IAuthenticationHandlerProvider, AuthenticationHandlerProvider>();
services.TryAddSingleton<IAuthenticationSchemeProvider, AuthenticationSchemeProvider>();
return services;
}
/// <summary>
/// Add core authentication services needed for <see cref="T:Microsoft.AspNetCore.Authentication.IAuthenticationService" />.
/// </summary>
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<AuthenticationOptions>(configureOptions);
return services;
}
}我們看到這里主要注冊了AuthenticationService, AuthenticationHandlerProvider, AuthenticationSchemeProvider這三個對象，如文章開頭所說，追本溯源，從使用開始，我們先看一下這三個對象是如何在認證體系中使用的，且是如何發揮作用的。
從使用開始
看一下我們的認證管道構建
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
...
app.UseAuthentication();
...
}
public static class AuthAppBuilderExtensions
{
public static IApplicationBuilder UseAuthentication( this IApplicationBuilder app)
{
if (app == null)
throw new ArgumentNullException(nameof (app));
return app.UseMiddleware<AuthenticationMiddleware>();
}
}這里使用了約定的注冊方式UseMiddleware，并且指定使用中間件AuthenticationMiddleware
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));
this._next = next;
this.Schemes = schemes;
}
public IAuthenticationSchemeProvider Schemes { get; set; }
public async Task Invoke(HttpContext context)
{
context.Features.Set<IAuthenticationFeature>((IAuthenticationFeature) new AuthenticationFeature()
{
OriginalPath = context.Request.Path,
OriginalPathBase = context.Request.PathBase
});
IAuthenticationHandlerProvider handlers = context.RequestServices.GetRequiredService<IAuthenticationHandlerProvider>();
foreach (AuthenticationScheme authenticationScheme in await this.Schemes.GetRequestHandlerSchemesAsync())
{
IAuthenticationRequestHandler handlerAsync = await handlers.GetHandlerAsync(context, authenticationScheme.Name) as IAuthenticationRequestHandler;
bool flag = handlerAsync != null;
if (flag)
flag = await handlerAsync.HandleRequestAsync();
if (flag)
return;
}
AuthenticationScheme authenticateSchemeAsync = await this.Schemes.GetDefaultAuthenticateSchemeAsync();
if (authenticateSchemeAsync != null)
{
AuthenticateResult authenticateResult = await context.AuthenticateAsync(authenticateSchemeAsync.Name); //實際的認證業務
if (authenticateResult?.Principal != null)
context.User = authenticateResult.Principal;
}
await this._next(context);
}
}在繼續往下之前，我們先看一下這個認證中間件的作用結果，當認證通過時，在HttpContext的User屬性（ClaimPrincipal）賦予身份標識，所以在后續的請求管道中都是基于認證結果中的身份標識做鑒權，這個我們會在后面的實際操作中會提到。
言歸正傳，在這里引出了我們的兩個對象AuthenticationHandlerProvider,AuthenticationSchemeProvider。
重要對象講解
IAuthenticationSchemeProvider
從名字來看，IAuthenticationSchemeProvider的作用應該是提供Scheme的，這也是Provider在微軟的風格里面起的作用（類似于工廠模式）。
這個Scheme是什么呢？很明顯，在Framework時代，也是有基于不同Scheme驗證的，比如Bearer，Cookie，在Aspnet Core中定義不同的Scheme代表著不同的認證處理方式，具體體現是在每個Scheme中包含對應的IAuthenticationHandler類型的Handler，由它來完成跟自身Scheme相關的認證處理。如果沒有定義會怎么樣？仔細看上面這塊源碼，只有當AuthenticationScheme不為空時才會做認證，否則一旦在Controller打上鑒權標簽[Authorize]，將會直接返回401，所以我們必須指定自己的Scheme。
那么我們在哪里指定我們的Scheme類似呢？我們先返回到ConfigureService的AddJwtBearer，使用過的朋友們肯定知道，這里獲取的Scheme是我們在ConfigureService通過Addxxx scheme指定的Scheme類型。這里我們是使用JWT的
在這里指定了TOptions 為JwtBearerOptions，而THandler為JwtBearerHandler。
public virtual AuthenticationBuilder AddScheme<TOptions, THandler>(
string authenticationScheme,
string displayName,
Action<TOptions> configureOptions)
where TOptions : AuthenticationSchemeOptions, new()
where THandler : AuthenticationHandler<TOptions>
{
return this.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
{
this.Services.Configure<AuthenticationOptions>((Action<AuthenticationOptions>) (o => o.AddScheme(authenticationScheme, (Action<AuthenticationSchemeBuilder>) (scheme =>
{
scheme.HandlerType = typeof (THandler);
scheme.DisplayName = displayName;
}))));
if (configureOptions != null)
this.Services.Configure<TOptions>(authenticationScheme, configureOptions);
this.Services.AddTransient<THandler>();
return this;
}注意這里TOptions 是需要繼承AuthenticationSchemeOptions的，在這里是JwtBearerOptions，而THandler是AuthenticationHandler<TOptions>類型的Handler，在這里是JwtBearerHandler。
我們回到Scheme的分析繼續往下，首先看一下AuthenticationScheme的定義
public class AuthenticationScheme
{
/// <summary>Constructor.</summary>
public AuthenticationScheme(string name, string displayName, Type handlerType)
{
if (name == null)
throw new ArgumentNullException(nameof (name));
if (handlerType == (Type) null)
throw new ArgumentNullException(nameof (handlerType));
if (!typeof (IAuthenticationHandler).IsAssignableFrom(handlerType))
throw new ArgumentException("handlerType must implement IAuthenticationHandler.");
this.Name = name;
this.HandlerType = handlerType;
this.DisplayName = displayName;
}
/// <summary>The name of the authentication scheme.</summary>
public string Name { get; }
/// <summary>
/// The display name for the scheme. Null is valid and used for non user facing schemes.
/// </summary>
public string DisplayName { get; }
/// <summary>
/// The <see cref="T:Microsoft.AspNetCore.Authentication.IAuthenticationHandler" /> type that handles this scheme.
/// </summary>
public Type HandlerType { get; }
}在這里可以看到，如果要使用Aspnet Core自身的認證體系，需先注冊Scheme，并且該Scheme必須指定一個類型為IAuthenticationHandler的Handler，否則會拋出異常。（這個其實在AddxxxScheme的時候已經指定了AuthenticationHandler）
我們再看一下IAuthenticationSchemeProvider的GetRequestHandlerSchemesAsync方法做了什么
public virtual Task<IEnumerable<AuthenticationScheme>> GetRequestHandlerSchemesAsync()
{
return Task.FromResult<IEnumerable<AuthenticationScheme>>((IEnumerable<AuthenticationScheme>) this._requestHandlers);
}這東西返回了_requestHandlers，這是什么？看代碼
public class AuthenticationSchemeProvider : IAuthenticationSchemeProvider
{
private readonly object _lock = new object();
private readonly AuthenticationOptions _options;
private readonly IDictionary<string, AuthenticationScheme> _schemes;
private readonly List<AuthenticationScheme> _requestHandlers;
/// <summary>
/// Creates an instance of <see cref="T:Microsoft.AspNetCore.Authentication.AuthenticationSchemeProvider" />
/// using the specified <paramref name="options" />,
/// </summary>
public AuthenticationSchemeProvider(IOptions<AuthenticationOptions> options)
: this(options, (IDictionary<string, AuthenticationScheme>) new Dictionary<string, AuthenticationScheme>((IEqualityComparer<string>) StringComparer.Ordinal))
{
}
/// <summary>
/// Creates an instance of <see cref="T:Microsoft.AspNetCore.Authentication.AuthenticationSchemeProvider" />
/// using the specified <paramref name="options" /> and <paramref name="schemes" />.
/// </summary>
protected AuthenticationSchemeProvider(
IOptions<AuthenticationOptions> options,
IDictionary<string, AuthenticationScheme> schemes)
{
this._options = options.Value;
IDictionary<string, AuthenticationScheme> dictionary = schemes;
if (dictionary == null)
throw new ArgumentNullException(nameof (schemes));
this._schemes = dictionary;
this._requestHandlers = new List<AuthenticationScheme>();
foreach (AuthenticationSchemeBuilder scheme in this._options.Schemes)
this.AddScheme(scheme.Build());
}
public virtual void AddScheme(AuthenticationScheme scheme)
{
if (this._schemes.ContainsKey(scheme.Name))
throw new InvalidOperationException("Scheme already exists: " + scheme.Name);
lock (this._lock)
{
if (this._schemes.ContainsKey(scheme.Name))
throw new InvalidOperationException("Scheme already exists: " + scheme.Name);
if (typeof (IAuthenticationRequestHandler).IsAssignableFrom(scheme.HandlerType))
this._requestHandlers.Add(scheme);
this._schemes[scheme.Name] = scheme;
}
}
.....
}這東西就是把我們在認證注冊服務中指定的scheme，通過解析出的AuthenticationSchemeProvider 的構造函數加載來的，進而返回一系列的List<AuthenticationScheme>，OK拿到這些scheme之后有什么用呢？這里引出了我們的第二個對象AuthenticationHandlerProvider，下面我們來了解一下。
IAuthenticationHandlerProvider
我們看到，AuthenticationMiddleware中用到了IAuthenticationHandlerProvider的GetHandlerAsync方法，那我們先看一下這個方法的作用
public class AuthenticationHandlerProvider : IAuthenticationHandlerProvider
{
private Dictionary<string, IAuthenticationHandler> _handlerMap = new Dictionary<string, IAuthenticationHandler>((IEqualityComparer<string>) StringComparer.Ordinal);
/// <summary>Constructor.</summary>
public AuthenticationHandlerProvider(IAuthenticationSchemeProvider schemes)
{
this.Schemes = schemes;
}
/// <summary>
/// The <see cref="T:Microsoft.AspNetCore.Authentication.IAuthenticationHandlerProvider" />.
/// </summary>
public IAuthenticationSchemeProvider Schemes { get; }
/// <summary>Returns the handler instance that will be used.</summary>
public async Task<IAuthenticationHandler> GetHandlerAsync( HttpContext context, string authenticationScheme)
{
if (this._handlerMap.ContainsKey(authenticationScheme))
return this._handlerMap[authenticationScheme];
AuthenticationScheme schemeAsync = await this.Schemes.GetSchemeAsync(authenticationScheme);
if (schemeAsync == null)
return (IAuthenticationHandler) null;
IAuthenticationHandler handler = (context.RequestServices.GetService(schemeAsync.HandlerType) ?? ActivatorUtilities.CreateInstance(context.RequestServices, schemeAsync.HandlerType)) as IAuthenticationHandler;
if (handler != null)
{
await handler.InitializeAsync(schemeAsync, context);
this._handlerMap[authenticationScheme] = handler;
}
return handler;
}
}在創建Handler的時候，是先從AuthenticationScheme中獲取，如果不存在則通過ActivatorUtilities創建。 獲取到Handle后，將會放在_handlerMap字典里面，當下次獲取Handler的時候，將直接從緩存中獲取。
IAuthenticationService
這個對象是在AuthenticationMiddleware中最后才用到的，而且是基于HttpContext的擴展被調用
public static class AuthenticationHttpContextExtensions
{
public static Task<AuthenticateResult> AuthenticateAsync(this HttpContext context, string scheme) =>
context.RequestServices.GetRequiredService<IAuthenticationService>().AuthenticateAsync(context, scheme);
....
}這里主要調用了IAuthenticationService的AuthenticateAsync方法，看一下這個方法做了什么
public class AuthenticationService : IAuthenticationService
{
public IAuthenticationSchemeProvider Schemes { get; }
public IAuthenticationHandlerProvider Handlers { get; }
public IClaimsTransformation Transform { get; }
public virtual async Task<AuthenticateResult> AuthenticateAsync(HttpContext context, string scheme)
{
if (scheme == null)
{
var scheme = (await this.Schemes.GetDefaultAuthenticateSchemeAsync())?.Name;
if (scheme == null)
throw new InvalidOperationException($"No authenticationScheme was specified, and there was no DefaultAuthenticateScheme found.");
}
var handler = await Handlers.GetHandlerAsync(context, scheme);
if(handler == null)
throw await this.CreateMissingHandlerException(scheme);
AuthenticateResult result = await handler.AuthenticateAsync();
if (result != null && result.Succeeded)
return AuthenticateResult.Success(new AuthenticationTicket(await Transform.TransformAsync(result.Principal), result.Properties, result.Ticket.AuthenticationScheme));
return result;
}
}這里其實就是我們在前面講的根據Scheme獲取對應的AuthenticationHandler，然后調用AuthenticateAsync()方法，這個方法調用了核心方法HandleAuthenticateOnceAsync，然后再調用HandleAuthenticateAsync()這個核心的認證方法。
從上圖看到這個HandleAuthenticateAsync是個抽象方法，我們的子類都需要實現這個方法的動作，基于本文的例子，我們看一下JwtBearerHandler的一個實際認證。
public class JwtBearerHandler : AuthenticationHandler<JwtBearerOptions>
{
protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
{
JwtBearerHandler jwtBearerHandler = this;
string token = (string) null;
object obj;
AuthenticationFailedContext authenticationFailedContext;
int num;
try
{
MessageReceivedContext messageReceivedContext = new MessageReceivedContext(jwtBearerHandler.Context, jwtBearerHandler.Scheme, jwtBearerHandler.Options);
await jwtBearerHandler.Events.MessageReceived(messageReceivedContext);
if (messageReceivedContext.Result != null)
return messageReceivedContext.Result;
token = messageReceivedContext.Token;
if (string.IsNullOrEmpty(token))
{
string header = (string) jwtBearerHandler.Request.Headers["Authorization"];
if (string.IsNullOrEmpty(header))
return AuthenticateResult.NoResult();
if (header.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
token = header.Substring("Bearer ".Length).Trim();
if (string.IsNullOrEmpty(token))
return AuthenticateResult.NoResult();
}
if (jwtBearerHandler._configuration == null && jwtBearerHandler.Options.ConfigurationManager != null)
{
OpenIdConnectConfiguration configurationAsync = await jwtBearerHandler.Options.ConfigurationManager.GetConfigurationAsync(jwtBearerHandler.Context.RequestAborted);
jwtBearerHandler._configuration = configurationAsync;
}
TokenValidationParameters validationParameters1 = jwtBearerHandler.Options.TokenValidationParameters.Clone();
if (jwtBearerHandler._configuration != null)
{
string[] strArray = new string[1]
{
jwtBearerHandler._configuration.Issuer
};
TokenValidationParameters validationParameters2 = validationParameters1;
IEnumerable<string> validIssuers = validationParameters1.get_ValidIssuers();
object obj1 = (validIssuers != null ? (object) validIssuers.Concat<string>((IEnumerable<string>) strArray) : (object) null) ?? (object) strArray;
validationParameters2.set_ValidIssuers((IEnumerable<string>) obj1);
TokenValidationParameters validationParameters3 = validationParameters1;
IEnumerable<SecurityKey> issuerSigningKeys = validationParameters1.get_IssuerSigningKeys();
IEnumerable<SecurityKey> securityKeys = (issuerSigningKeys != null ? issuerSigningKeys.Concat<SecurityKey>((IEnumerable<SecurityKey>) jwtBearerHandler._configuration.get_SigningKeys()) : (IEnumerable<SecurityKey>) null) ?? (IEnumerable<SecurityKey>) jwtBearerHandler._configuration.get_SigningKeys();
validationParameters3.set_IssuerSigningKeys(securityKeys);
}
List<Exception> exceptionList = (List<Exception>) null;
foreach (ISecurityTokenValidator securityTokenValidator in (IEnumerable<ISecurityTokenValidator>) jwtBearerHandler.Options.SecurityTokenValidators)
{
if (securityTokenValidator.CanReadToken(token))
{
SecurityToken securityToken;
ClaimsPrincipal claimsPrincipal;
try
{
claimsPrincipal = securityTokenValidator.ValidateToken(token, validationParameters1, ref securityToken);
}
catch (Exception ex)
{
jwtBearerHandler.Logger.TokenValidationFailed(ex);
if (jwtBearerHandler.Options.RefreshOnIssuerKeyNotFound && jwtBearerHandler.Options.ConfigurationManager != null && ex is SecurityTokenSignatureKeyNotFoundException)
jwtBearerHandler.Options.ConfigurationManager.RequestRefresh();
if (exceptionList == null)
exceptionList = new List<Exception>(1);
exceptionList.Add(ex);
continue;
}
jwtBearerHandler.Logger.TokenValidationSucceeded();
TokenValidatedContext validatedContext = new TokenValidatedContext(jwtBearerHandler.Context, jwtBearerHandler.Scheme, jwtBearerHandler.Options);
validatedContext.Principal = claimsPrincipal;
validatedContext.SecurityToken = securityToken;
TokenValidatedContext tokenValidatedContext = validatedContext;
await jwtBearerHandler.Events.TokenValidated(tokenValidatedContext);
if (tokenValidatedContext.Result != null)
return tokenValidatedContext.Result;
if (jwtBearerHandler.Options.SaveToken)
tokenValidatedContext.Properties.StoreTokens((IEnumerable<AuthenticationToken>) new AuthenticationToken[1]
{
new AuthenticationToken()
{
Name = "access_token",
Value = token
}
});
tokenValidatedContext.Success();
return tokenValidatedContext.Result;
}
}
if (exceptionList == null)
return AuthenticateResult.Fail("No SecurityTokenValidator available for token: " + token ?? "[null]");
authenticationFailedContext = new AuthenticationFailedContext(jwtBearerHandler.Context, jwtBearerHandler.Scheme, jwtBearerHandler.Options)
{
Exception = exceptionList.Count == 1 ? exceptionList[0] : (Exception) new AggregateException((IEnumerable<Exception>) exceptionList)
};
await jwtBearerHandler.Events.AuthenticationFailed(authenticationFailedContext);
return authenticationFailedContext.Result == null ? AuthenticateResult.Fail(authenticationFailedContext.Exception) : authenticationFailedContext.Result;
}
catch (Exception ex)
{
obj = (object) ex;
num = 1;
}
if (num == 1)
{
Exception ex = (Exception) obj;
jwtBearerHandler.Logger.ErrorProcessingMessage(ex);
authenticationFailedContext = new AuthenticationFailedContext(jwtBearerHandler.Context, jwtBearerHandler.Scheme, jwtBearerHandler.Options)
{
Exception = ex
};
await jwtBearerHandler.Events.AuthenticationFailed(authenticationFailedContext);
if (authenticationFailedContext.Result != null)
return authenticationFailedContext.Result;
Exception source = obj as Exception;
if (source == null)
throw obj;
ExceptionDispatchInfo.Capture(source).Throw();
authenticationFailedContext = (AuthenticationFailedContext) null;
}
obj = (object) null;
token = (string) null;
AuthenticateResult authenticateResult;
return authenticateResult;
}
}這個方法有點長，主要是從Request.Headers里面獲取Authorization的Bearer出來解析，再在AddJwtBearer中傳入的委托參數JwtBearerOptions的TokenValidationParameters屬性作為依據進行對比來進行認證是否通過與否。
看完了這篇文章，相信你對ASP.NET中Core Authentication進行認證的流程有了一定的了解，想了解更多相關知識，歡迎關注億速云行業資訊頻道，感謝各位的閱讀！
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