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
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=316888
HttpConfiguration 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)：
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=316888
OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
{
AllowInsecureHttp = true,
TokenEndpointPath = new PathString("/oauth/token"),
AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
Provider = new CustomAuthorizationServerProvider()
};
// Token Generation
app.UseOAuthAuthorizationServer(OAuthServerOptions);
app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
HttpConfiguration config = new HttpConfiguration();
WebApiConfig.Register(config);
app.UseWebApi(config);
}
}
}
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：
using System.Security.Claims;
using System.Threading.Tasks;
using Microsoft.Owin.Security.OAuth;
namespace OAuthExample.Providers
{
public class CustomAuthorizationServerProvider : OAuthAuthorizationServerProvider
{
///
/// 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.
///
/// The context of the event carries information in and results out.
public override async Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
{
context.Validated();
}
///
/// 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
///
/// The context of the event carries information in and results out.
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);
}
}
}
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：
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=316888
OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
{
AllowInsecureHttp = true,
TokenEndpointPath = new PathString("/token"),
AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
Provider = new CustomAuthorizationServerProvider()
};
// Token Generation
app.UseOAuthAuthorizationServer(OAuthServerOptions);
app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
HttpConfiguration config = new HttpConfiguration();
WebApiConfig.Register(config);
app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);
app.UseWebApi(config);
}
}
}
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：
[RoutePrefix("api/Orders")]
public class OrdersController : ApiController
{
[Authorize]
[Route("")]
public IHttpActionResult Get()
{
return Ok(Order.CreateOrders());
}
}
#region Helpers
public 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 CreateOrders()
{
List OrderList = new List
{
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
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:
模拟授权访问，先获取令牌：
将令牌附加到Order请求，再次尝试访问：
可以看到已经能正常获取到数据，打开调试，看一下方法中的变量如下：
总结
一直觉得WebApi和MVC很多都一样的东西，在实际应用中还是有不少区别，关于OAuth、JWT等等在WebApi中使用较多，本文是参照文末连接做的一个总结，细看下原po的时间都已经是14年的文章了。马上要aspnet core 3.2都要发布了，现在却还在补以前的知识，惭愧的很！
参考链接：
Token Based Authentication using ASP.NET Web API 2, Owin, and Identity
Enable OAuth Refresh Tokens in AngularJS App using ASP .NET Web API 2, and Owin
