Asp.Net Core Authentication Middleware And Generate Token

 

写在前面

  本文版权归博客园和作者吴双本人共同所有 转载和爬虫请注明原文地址 cnblogs.com/tdws

     After using OWIN for months for basic OAuth authentication, it’s apparent that Microsoft is abandoning OWIN . This isn’t necessarily a bad thing. .NET Core is built on a similar structure as that which was implemented in OWIN. Essentially, we have a familiar middleware pipeline.

    这句话出自老外的博客，在使用Owin的OAuth身份认证几个月后，发现微软在逐渐放弃OWIN,这未必是一件坏事情，.NET Core在一个和OWIN所实现的相似结构之上。我们有一个和OWIN极为相似的中间件管道。

　  想必了解或者使用过OWIN的朋友们，在做.NET Core应用的时候都会有如上描述的这种感觉。就我个人的理解，微软在早几年推出OWIN的时候，就希望将管道留给用户，就以Startup.cs为管道配置和应用入口，OWIN脱离了Asp.Net管道事件，我们可以将任何中间件在管道中随意插拔。在OWIN中为我们提供了完备的认证流程，和一套完整的规范。比如 Microsoft.Owin.Security.OAuth等，在使用OWIN时，我们可以使用OWIN的默认实现，也可以实现其接口，自定义我们自己的实现方式。有关Microsoft OWIN的内容，不是本篇分享的主题，推荐腾飞的 MVC5 - ASP.NET Identity登录原理 - Claims-based认证和OWIN  和蟋蟀哥的 ASP.NET WebApi OWIN 实现 OAuth 2.0  。

Token 

 　本篇分享主要关注在.NET Core的认证机制。无论我们是使用WebApi还是MvcWeb App，了解微软的认证机制总是有好处的。认证是应用API服务器识别用户身份的过程，token是更现代的认证方式，简化权限管理，降低服务器负载。在认证过程中，最重要的就是拿到token, token包含或者应该包含什么信息呢？

　　　　1.这个人是谁？

　　　　2.这个人可以用此token访问什么样的内容？（scope）

　　　　3.token的过期时间 (expire)

　　　　4.谁发行的token。

　　　　5.其他任何你希望加入的声明（Claims）

　那我们为什么要使用token呢？使用session或者用redis来实现stateServer不好吗？

　　　　1.token是低（无）状态的，Statelessness

　　　　2.token可以与移动端应用紧密结合

　　　　3.支持多平台服务器和分布式微服务

拿到token后如何带入HTTP请求传给后台？

 　答案是两种方式，Cookies和Authorization Header。那么什么时候放到Cookies中，什么时候又放到Authentication中呢？

第一，如果是在Web应用，则放到Cookies当中，并且应该是HttpOnly的，js不能直接对其进行操作，安全性会比将其存在Web Stroage中好一些，因为在Web Storage当中的内容，可以很容的被潜在的XSS脚本攻击并获取。在HttpOnly的cookies当中会相对安全一些，不过也有潜在的CSRF跨站伪造请求的危险，不过这种hack的手段成功率是很低的，有兴趣的朋友可以自行看一下CSRF原理。

第二，如果是手机移动端应用的话，那一定是存储在App本地，并由Authorization Header带到后台并得到身份认证。

WebApp Cookies Authentication

上一段前两周写的最原始的小Demo吧，没有数据库访问等，可根据demo自行改变 ，现在的新代码已经加入了很多业务在其中

startup.cs代码

using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Authentication;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System.Collections.Generic;
using System.Security.Claims;
using Wings.AuthenticationApp.Middleware;

namespace Wings.AuthenticationApp
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            Configuration = builder.Build();

        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseCookieAuthentication(CookieAuthMiddleware.GetOptions());
            app.UseOwin();
            app.UseCors(a => { a.AllowAnyOrigin(); });
            app.UseMvc();
            // Listen for login and logout requests
            app.Map("/login", builder =>
            {
                builder.Run(async context =>
                {
                    var name = context.Request.Form["name"];
                    var pwd = context.Request.Form["pwd"];
                    if (name == "wushuang" && pwd == "wushuang")
                    {

                        var claims = new List<Claim>() { new Claim("name", name), new Claim("role", "admin") };
                        var identity = new ClaimsIdentity(claims, "password");
                        var principal = new ClaimsPrincipal(identity);
                        await context.Authentication.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, principal);
                        context.Response.Redirect("http://www.baidu.com");
                    }
                    else
                    {
                        await context.Authentication.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
                        context.Response.Redirect("http://www.google.com");
                    }
                });
            });

            //app.Map("/logout", builder =>
            //{
            //    builder.Run(async context =>
            //    {
            //        // Sign the user out / clear the auth cookie
            //        await context.Authentication.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);

            //        // Perform a simple redirect after logout
            //        context.Response.Redirect("/");
            //    });
            //});
            
        }

    }
}

下面是Middleware---->CookieAuthMiddleware.cs的代码，

using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Claims;
using System.Security.Principal;
using System.Threading.Tasks;

namespace Wings.AuthenticationApp.Middleware
{
    public class CookieAuthMiddleware
    {
        public static CookieAuthenticationOptions GetOptions()
        {
            return new CookieAuthenticationOptions
            {
                AutomaticAuthenticate = true,
                AutomaticChallenge = true,
                LoginPath = new PathString("/login"),
                LogoutPath = new PathString("/logout"),
                AccessDeniedPath = new PathString("/test"),
                CookieHttpOnly = false,  //默认就是True了
                CookieName = "wings_access_token",
                SlidingExpiration = true,
                CookieManager = new ChunkingCookieManager()
            };
        }
    }
    public static class IdentityExtension
    {
        public static string FullName(this IIdentity identity)
        {
            var claim = ((ClaimsIdentity)identity).FindFirst("name");
            return (claim != null) ? claim.Value : string.Empty;
        }
        public static string Role(this IIdentity identity)
        {
            var claim = ((ClaimsIdentity)identity).FindFirst("role");
            return (claim != null) ? claim.Value : string.Empty;
        }
    }
}

对应如上demo,简单测试一下，结果如下：

首先使用错误的密码，来请求token endpoint，接下来我们看一下即使窗口，当有请求进入的时候，我用如下代码判断用户的认证情况，拿到的结果必然是false：

接下来，我使用正确的账号密码，来打入token,判断结果一定为true，所以我使用自定义的拓展方法，来获取下，该用户token的信息:

如上demo没有加入一些容错机制，请注意。在用户认证成功后，可以进入带有Authorize Attribute的Action,否则401.如下是几个重要参数的解释

自定义Authentication Middle生产Token

 Startup.cs 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Wings.TokenAuth.Middleware;
using System.Security.Claims;
using Microsoft.IdentityModel.Tokens;
using System.Text;
using Microsoft.Extensions.Options;

namespace Wings.TokenAuth
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();
        }

        // The secret key every token will be signed with.
        // In production, you should store this securely in environment variables
        // or a key management tool. Don't hardcode this into your application!
        private static readonly string secretKey = "mysupersecret_secretkey!123";

        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(LogLevel.Debug);
            loggerFactory.AddDebug();

            app.UseStaticFiles();

            // Add JWT generation endpoint:
            var signingKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(secretKey));
            var options = new TokenProviderOptions
            {
                Audience = "ExampleAudience",
                Issuer = "ExampleIssuer",
                SigningCredentials = new SigningCredentials(signingKey, SecurityAlgorithms.HmacSha256),
            };

            app.UseMiddleware<TokenProviderMiddleware>(Options.Create(options));

            app.UseMvc();
        }
    }
}

TokenProviderOptions.cs

using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Security.Claims;
using System.Threading.Tasks;

namespace Wings.TokenAuth.Middleware
{
    public class TokenProviderOptions
    {
        public string Path { get; set; } = "/token";

        public string Issuer { get; set; }

        public string Audience { get; set; }

        public TimeSpan Expiration { get; set; } = TimeSpan.FromMinutes(5);

        public SigningCredentials SigningCredentials { get; set; }
    }
    public class TokenProviderMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly TokenProviderOptions _options;

        public TokenProviderMiddleware(
          RequestDelegate next,
          IOptions<TokenProviderOptions> options)
        {
            _next = next;
            _options = options.Value;
        }

        public Task Invoke(HttpContext context)
        {
            // If the request path doesn't match, skip
            if (!context.Request.Path.Equals(_options.Path, StringComparison.Ordinal))
            {
　　　　　　　　　　　　 //use new JwtSecurityTokenHandler().ValidateToken() to valid token
                return _next(context);
            }

            // Request must be POST with Content-Type: application/x-www-form-urlencoded
            if (!context.Request.Method.Equals("POST")
              || !context.Request.HasFormContentType)
            {
                context.Response.StatusCode = 400;
                return context.Response.WriteAsync("Bad request.");
            }

            return GenerateToken(context);
        }
        private async Task GenerateToken(HttpContext context)
        {
            var username = context.Request.Form["username"];
            var password = context.Request.Form["password"];

            var identity = await GetIdentity(username, password);
            if (identity == null)
            {
                context.Response.StatusCode = 400;
                await context.Response.WriteAsync("Invalid username or password.");
                return;
            }

            var now = DateTime.UtcNow;

            // Specifically add the jti (random nonce), iat (issued timestamp), and sub (subject/user) claims.
            // You can add other claims here, if you want:
            var claims = new Claim[]
            {
    new Claim(JwtRegisteredClaimNames.Sub, username),
    new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
    new Claim(JwtRegisteredClaimNames.Iat, ToUnixEpochDate(now).ToString(), ClaimValueTypes.Integer64)
            };

            // Create the JWT and write it to a string
            var jwt = new JwtSecurityToken(
              issuer: _options.Issuer,
              audience: _options.Audience,
              claims: claims,
              notBefore: now,
              expires: now.Add(_options.Expiration),
              signingCredentials: _options.SigningCredentials);
            var encodedJwt = new JwtSecurityTokenHandler().WriteToken(jwt);

            var response = new
            {
                access_token = encodedJwt,
                expires_in = (int)_options.Expiration.TotalSeconds
            };

            // Serialize and return the response
            context.Response.ContentType = "application/json";
            await context.Response.WriteAsync(JsonConvert.SerializeObject(response, new JsonSerializerSettings { Formatting = Formatting.Indented }));
        }

        private Task<ClaimsIdentity> GetIdentity(string username, string password)
        {
            // DON'T do this in production, obviously!
            if (username == "wushuang" && password == "wushuang")
            {
                return Task.FromResult(new ClaimsIdentity(new System.Security.Principal.GenericIdentity(username, "Token"), new Claim[] { }));
            }

            // Credentials are invalid, or account doesn't exist
            return Task.FromResult<ClaimsIdentity>(null);
        }

        public static long ToUnixEpochDate(DateTime date)
  => (long)Math.Round((date.ToUniversalTime() - new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero)).TotalSeconds);


    }
}

下面上测试结果：

使用错误的账户和密码请求token

使用正确的账户和密码来请求，返回结果如下：

如果，您认为阅读这篇博客让您有些收获，不妨点击一下右下加【推荐】按钮。
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因为，我的分享热情也离不开您的肯定支持。

感谢您的阅读，我将持续输出分享，我是蜗牛, 保持学习，谨记谦虚。不端不装，有趣有梦。

参考文章和论文，不仅限于如下几篇，感谢国外大佬们有深度的分享：

http://stackoverflow.com/questions/29055477/oauth-authorization-service-in-asp-net-core

https://stormpath.com/blog/token-authentication-asp-net-core

https://docs.microsoft.com/en-us/aspnet/core/fundamentals/middleware#fundamentals-middleware

https://docs.microsoft.com/en-us/aspnet/core/security/authentication/cookie#controlling-cookie-options

https://stormpath.com/blog/token-authentication-asp-net-core