基于令牌的身份验证

基于令牌的身份验证主要区别于以前常用的基于cookie的身份验证，基于cookie的身份验证在B/S架构中使用比较多，但是在Web Api中因其特殊性，基于cookie的身份验证已经不适合了，因为并不是每一个调用api的客户端都是从浏览器发起，我们面临的客户端可能是手机、平板、或者app。

使用基于Token令牌的身份验证有一些好处：

服务器的可伸缩性：发送到服务器的令牌是自包含的，不依赖于共享会话存储
松散耦合：前端应用程序位于特定的身份验证机制耦合，令牌是从服务器生成的，并且API构建方式可理解该令牌并进行身份验证
适用于移动设备：cookie依赖于浏览器，存储于本机平台，使用token将简化流程

构建后端API

步骤一：创建Web Api 项目

为了进行代码演示，创建一个相对比较干净的环境，我们新建一个项目，演示本次功能，本文使用Visual Studio 2017和 .NTE Framework 4.7。

在Vs中选择新建项目，选择ASP.NET Web 应用程序(.NET Framework) ,命名为OauthExample或者随便你喜欢的名字，然后下一步，选择空模板。ok

步骤二：安装Owin包，并设置“StartUp”类

项目右键，管理Nuget程序包，分别安装

Microsoft.AspNet.WebApi.Owin

Microsoft.Owin.Host.SystemWeb

也可以在程序包管理器输入如下代码安装：

Install-Package Microsoft.AspNet.WebApi.Owin 
Install-Package Microsoft.Owin.Host.SystemWeb

等待安装完成。

右键项目，移除Global.asax,右键项目，添加OWIN StartUp 类，然后修改代码如下：

using System.Web.Http;
using Microsoft.Owin;
using Owin;[assembly: OwinStartup(typeof(OAuthExample.Startup))]namespace OAuthExample
{public class Startup{public void Configuration(IAppBuilder app){// 有关如何配置应用程序的详细信息，请访问 https://go.microsoft.com/fwlink/?LinkID=316888HttpConfiguration config = new HttpConfiguration();WebApiConfig.Register(config);app.UseWebApi(config);}}
}

简要说明

assembly属性设置了启动时要触发的类
HttpConfiguration对象用于配置API路由等，我们将对象传递给Register方法
UasWebApi接收对象config，该方法将把Web Api连接到我们的OWIN服务管道

完成后编译一下，检查是否能通过，如果有问题检查一下Nuget包是否安装正确。

步骤三：添加对OAuth承载令牌生成的支持

安装Owin包，Microsoft.Owin.Security.OAuth，再次打开StartUp文件，修改代码如下(斜体)：

复制代码

using System;
using System.Web.Http;
using Microsoft.Owin;
using Microsoft.Owin.Security.OAuth;
using Owin;[assembly: OwinStartup(typeof(OAuthExample.Startup))]namespace OAuthExample
{public class Startup{public void Configuration(IAppBuilder app){// 有关如何配置应用程序的详细信息，请访问 https://go.microsoft.com/fwlink/?LinkID=316888OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions(){AllowInsecureHttp = true,TokenEndpointPath = new PathString("/oauth/token"),AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),Provider = new CustomAuthorizationServerProvider()};// Token Generationapp.UseOAuthAuthorizationServer(OAuthServerOptions);app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());HttpConfiguration config = new HttpConfiguration();WebApiConfig.Register(config);app.UseWebApi(config);}}
}

复制代码

在这里，我们从类“OAuthAuthorizationServerOptions”创建了新实例，并设置选项如下：

允许客户端使用http协议请求
令牌生成路径为"/oauth/token" ,即通过路径host: port:/oauth/token 获取令牌信息
设置令牌的有效时间为一天，如果用户在令牌发出24小时候使用令牌进行身份验证，请求将被拒绝，并返回401状态码
我们在名为“CustomAuthorizationServerProvider”的类中实现了如何用户票据的验证和发放

最后我们将此选项传递给扩展方法“ UseOAuthAuthorizationServer”，以便将身份验证中间件添加到管道中。

步骤四：实现“CustomAuthorizationServerProvider”类

在项目中添加名为“ Providers”的新文件夹，然后添加名为“ SimpleAuthorizationServerProvider”的新类，在下面粘贴代码片段：

复制代码

using System.Security.Claims;
using System.Threading.Tasks;
using Microsoft.Owin.Security.OAuth;namespace OAuthExample.Providers
{public class CustomAuthorizationServerProvider : OAuthAuthorizationServerProvider{/// <summary>/// Called to validate that the origin of the request is a registered "client_id", and that the correct credentials for that client are/// present on the request. If the web application accepts Basic authentication credentials,/// context.TryGetBasicCredentials(out clientId, out clientSecret) may be called to acquire those values if present in the request header. If the web/// application accepts "client_id" and "client_secret" as form encoded POST parameters,/// context.TryGetFormCredentials(out clientId, out clientSecret) may be called to acquire those values if present in the request body./// If context.Validated is not called the request will not proceed further./// </summary>/// <param name="context">The context of the event carries information in and results out.</param>public override async Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context){context.Validated();}/// <summary>/// Called when a request to the Token endpoint arrives with a "grant_type" of "password". This occurs when the user has provided name and password/// credentials directly into the client application's user interface, and the client application is using those to acquire an "access_token" and/// optional "refresh_token". If the web application supports the/// resource owner credentials grant type it must validate the context.Username and context.Password as appropriate. To issue an/// access token the context.Validated must be called with a new ticket containing the claims about the resource owner which should be associated/// with the access token. The application should take appropriate measures to ensure that the endpoint isn’t abused by malicious callers./// The default behavior is to reject this grant type./// See also http://tools.ietf.org/html/rfc6749#section-4.3.2/// </summary>/// <param name="context">The context of the event carries information in and results out.</param>public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context){context.OwinContext.Response.Headers.Add("Access-Control-Allow-Origin", new[] { "*" });//这里是验证用户名和密码，可以根据项目情况自己实现if (!(context.UserName == "zhangsan" && context.Password == "123456")){context.SetError("invalid_grant", "The user name or password is incorrect.");return;}//可以随便添加var identity = new ClaimsIdentity(context.Options.AuthenticationType);identity.AddClaim(new Claim("sub", context.UserName));identity.AddClaim(new Claim("role", "user"));context.Validated(identity);}}
}

复制代码

步骤五：允许ASP.NET Web Api跨域请求

使用nuget安装程序包，Install-Package Microsoft.Owin.Cors

然后在Startup类中添加如下代码，最终代码如下：

复制代码

using System;
using System.Web.Http;
using Microsoft.Owin;
using Microsoft.Owin.Security.OAuth;
using OAuthExample.Providers;
using Owin;[assembly: OwinStartup(typeof(OAuthExample.Startup))]namespace OAuthExample
{public class Startup{public void Configuration(IAppBuilder app){// 有关如何配置应用程序的详细信息，请访问 https://go.microsoft.com/fwlink/?LinkID=316888OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions(){AllowInsecureHttp = true,TokenEndpointPath = new PathString("/token"),AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),Provider = new CustomAuthorizationServerProvider()};// Token Generationapp.UseOAuthAuthorizationServer(OAuthServerOptions);app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());HttpConfiguration config = new HttpConfiguration();WebApiConfig.Register(config);app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);app.UseWebApi(config);}}
}

复制代码

代码测试

我们添加一个测试空的Order控制，用来测试一下上面的实现：

复制代码

[RoutePrefix("api/Orders")]public class OrdersController : ApiController{[Authorize][Route("")]public IHttpActionResult Get(){return Ok(Order.CreateOrders());}}#region Helperspublic class Order{public int OrderID { get; set; }public string CustomerName { get; set; }public string ShipperCity { get; set; }public Boolean IsShipped { get; set; }public static List<Order> CreateOrders(){List<Order> OrderList = new List<Order> {new Order {OrderID = 10248, CustomerName = "Taiseer Joudeh", ShipperCity = "Amman", IsShipped = true },new Order {OrderID = 10249, CustomerName = "Ahmad Hasan", ShipperCity = "Dubai", IsShipped = false},new Order {OrderID = 10250,CustomerName = "Tamer Yaser", ShipperCity = "Jeddah", IsShipped = false },new Order {OrderID = 10251,CustomerName = "Lina Majed", ShipperCity = "Abu Dhabi", IsShipped = false},new Order {OrderID = 10252,CustomerName = "Yasmeen Rami", ShipperCity = "Kuwait", IsShipped = true}};return OrderList;}}#endregion

复制代码

下面使用PostMan进行模拟测试.

在未授权时，直接访问 http://localhost:56638/api/orders得到如下结果: