asp.net core策略授权

在《asp.net core认证与授权》中讲解了固定和自定义角色授权系统权限，其实我们还可以通过其他方式来授权，比如可以通过角色组，用户名，生日等，但这些主要取决于ClaimTypes，其实我们也可以自定义键值来授权，这些统一叫策略授权，其中更强大的是，我们可以自定义授权Handler来达到灵活授权，下面一一展开。

注意：下面的代码只是部分代码，完整代码参照：https://github.com/axzxs2001/Asp.NetCoreExperiment/tree/master/Asp.NetCoreExperiment/%E6%9D%83%E9%99%90%E7%AE%A1%E7%90%86/PolicyPrivilegeManagement

首先看基于角色组，或用户名，或基于ClaimType或自定义键值等授权策略，这些都是通过Services.AddAuthorization添加，并且是AuthorizationOptions来AddPolicy，这里策略的名称统一用RequireClaim来命名，不同的请求的策略名称各不相同，如用户名时就用policy.RequireUserName()，同时，在登录时，验证成功后，要添加相应的Claim到ClaimsIdentity中：

Startup.cs

       public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            services.AddAuthorization(options =>
            {
                //基于角色的策略
                 options.AddPolicy("RequireClaim", policy => policy.RequireRole("admin", "system"));
                //基于用户名
                //options.AddPolicy("RequireClaim", policy => policy.RequireUserName("桂素伟"));
                //基于Claim
                //options.AddPolicy("RequireClaim", policy => policy.RequireClaim(ClaimTypes.Country,"中国"));
                //自定义值
                // options.AddPolicy("RequireClaim", policy => policy.RequireClaim("date","2017-09-02"));

            }).AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options =>{
                options.LoginPath = new PathString("/login");
                options.AccessDeniedPath = new PathString("/denied");
            });          
        }

HomeController.cs

using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using PolicyPrivilegeManagement.Models;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.Cookies;
using System.Security.Claims;
namespace PolicyPrivilegeManagement.Controllers
{
    [Authorize(Policy = "RequireClaim")]
    public class HomeController : Controller
    {
        PermissionHandler _permissionHandler;
        public HomeController(IAuthorizationHandler permissionHandler)
        {
            _permissionHandler = permissionHandler as PermissionHandler;
        }
        public IActionResult Index()
        {
            return View();
        }
        public IActionResult PermissionAdd()
        {           
            return View();
        }

        public IActionResult Contact()
        {
            ViewData["Message"] = "Your contact page.";
            return View();
        }
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }
        [AllowAnonymous]
        [HttpGet("login")]
        public IActionResult Login(string returnUrl = null)
        {
            TempData["returnUrl"] = returnUrl;
            return View();
        }
        [AllowAnonymous]
        [HttpPost("login")]
        public async Task<IActionResult> Login(string userName, string password, string returnUrl = null)
        {
            var list = new List<dynamic> {
                new { UserName = "gsw", Password = "111111", Role = "admin",Name="桂素伟",Country="中国",Date="2017-09-02",BirthDay="1979-06-22"},
                new { UserName = "aaa", Password = "222222", Role = "system",Name="测试A" ,Country="美国",Date="2017-09-03",BirthDay="1999-06-22"}
            };
            var user = list.SingleOrDefault(s => s.UserName == userName && s.Password == password);
            if (user != null)
            {
                //用户标识
                var identity = new ClaimsIdentity(CookieAuthenticationDefaults.AuthenticationScheme);
                identity.AddClaim(new Claim(ClaimTypes.Sid, userName));
                identity.AddClaim(new Claim(ClaimTypes.Name, user.Name));
                identity.AddClaim(new Claim(ClaimTypes.Role, user.Role));
                identity.AddClaim(new Claim(ClaimTypes.Country, user.Country));
                identity.AddClaim(new Claim("date", user.Date));
                await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, new ClaimsPrincipal(identity));
                if (returnUrl == null)
                {
                    returnUrl = TempData["returnUrl"]?.ToString();
                }
                if (returnUrl != null)
                {
                    return Redirect(returnUrl);
                }
                else
                {
                    return RedirectToAction(nameof(HomeController.Index), "Home");
                }
            }
            else
            {
                const string badUserNameOrPasswordMessage = "用户名或密码错误！";
                return BadRequest(badUserNameOrPasswordMessage);
            }
        }
        [HttpGet("logout")]
        public async Task<IActionResult> Logout()
        {
            await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
            return RedirectToAction("Index", "Home");
        }
        [AllowAnonymous]
        [HttpGet("denied")]
        public IActionResult Denied()
        {
            return View();
        }
    }
}

上面的授权策略都相对简单，单一，使用场景也很有限，就和固定角色授权如出一辙，其实可以用更好的来例用授权，那就是自定义授权Handler，我们在《asp.net core认证与授权》一文中，是通过中间件来达到自定义解色的，现在我们换个思路，通过自定义授权Handler来实现。

首先定义一个UserPermission，即用户权限实体类

    /// <summary>
    /// 用户权限
    /// </summary>
    public class UserPermission
    {
        /// <summary>
        /// 用户名
        /// </summary>
        public string UserName
        { get; set; }
        /// <summary>
        /// 请求Url
        /// </summary>
        public string Url
        { get; set; }
    }

接下来定义一个PermissionRequirement，为请求条件实体类

    /// <summary>
    /// 必要参数类
    /// </summary>
    public class PermissionRequirement : IAuthorizationRequirement
    {
        /// <summary>
        /// 用户权限集合
        /// </summary>
        public  List<UserPermission> UserPermissions { get;private set; }
        /// <summary>
        /// 无权限action
        /// </summary>
        public string DeniedAction { get; set; }
        /// <summary>
        /// 构造
        /// </summary>
        /// <param name="deniedAction">无权限action</param>
        /// <param name="userPermissions">用户权限集合</param>
        public PermissionRequirement(string deniedAction, List<UserPermission> userPermissions)
        {
            DeniedAction = deniedAction;
            UserPermissions = userPermissions;
        }
    }

再定义自定义授权Hanlder，我们命名为PermissionHandler，此类必需继承AuthorizationHandler<T>，只用实现public virtualTask HandleAsync(AuthorizationHandlerContext context)，些方法是用户请求时验证是否授权的主方法，所以实现与自定义角色中间件的Invoke很相似。

using Microsoft.AspNetCore.Authorization;
using System.Collections.Generic;
using System.Linq;
using System.Security.Claims;
using System.Threading.Tasks;
namespace PolicyPrivilegeManagement.Models
{
    /// <summary>
    /// 权限授权Handler
    /// </summary>
    public class PermissionHandler : AuthorizationHandler<PermissionRequirement>
    {
        /// <summary>
        /// 用户权限
        /// </summary>
        public List<UserPermission> UserPermissions { get; set; }
        protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, PermissionRequirement requirement)
        {
            //赋值用户权限
            UserPermissions = requirement.UserPermissions;
            //从AuthorizationHandlerContext转成HttpContext，以便取出表求信息
            var httpContext = (context.Resource as Microsoft.AspNetCore.Mvc.Filters.AuthorizationFilterContext).HttpContext;
            //请求Url
            var questUrl = httpContext.Request.Path.Value.ToLower();
            //是否经过验证
            var isAuthenticated = httpContext.User.Identity.IsAuthenticated;
            if (isAuthenticated)
            {
                if (UserPermissions.GroupBy(g => g.Url).Where(w => w.Key.ToLower() == questUrl).Count() > 0)
                {
                    //用户名
                    var userName = httpContext.User.Claims.SingleOrDefault(s => s.Type == ClaimTypes.Sid).Value;
                    if (UserPermissions.Where(w => w.UserName == userName && w.Url.ToLower() == questUrl).Count() > 0)
                    {
                        context.Succeed(requirement);
                    }
                    else
                    {
                        //无权限跳转到拒绝页面
                        httpContext.Response.Redirect(requirement.DeniedAction);
                    }
                }
                else
                {
                    context.Succeed(requirement);
                }
            }
            return Task.CompletedTask;
        }
    }
}

此次的Startup.cs的ConfigureServices发生了变化，如下

       public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            services.AddAuthorization(options =>
            {               
                //自定义Requirement,userPermission可从数据库中获得
                var userPermission = new List<UserPermission> {
                              new UserPermission {  Url="/", UserName="gsw"},
                              new UserPermission {  Url="/home/permissionadd", UserName="gsw"},
                              new UserPermission {  Url="/", UserName="aaa"},
                              new UserPermission {  Url="/home/contact", UserName="aaa"}
                          };
                options.AddPolicy("Permission",
                          policy => policy.Requirements.Add(new PermissionRequirement("/denied", userPermission)));
            }).AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options =>{
                options.LoginPath = new PathString("/login");
                options.AccessDeniedPath = new PathString("/denied");
            });
            //注入授权Handler
            services.AddSingleton<IAuthorizationHandler, PermissionHandler>();
        }

HomeController中代码如下：

using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using PolicyPrivilegeManagement.Models;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.Cookies;
using System.Security.Claims;
namespace PolicyPrivilegeManagement.Controllers
{
    [Authorize(Policy = "Permission")]
    public class HomeController : Controller
    {
        PermissionHandler _permissionHandler;
        public HomeController(IAuthorizationHandler permissionHandler)
        {
            _permissionHandler = permissionHandler as PermissionHandler;
        }
        public IActionResult Index()
        {
            return View();
        }
        public IActionResult PermissionAdd()
        {           
            return View();
        }
        [HttpPost("addpermission")]
        public IActionResult AddPermission(string url,string userName)
        {       
            //添加权限
            _permissionHandler.UserPermissions.Add(new UserPermission { Url = url, UserName = userName });
            return Content("添加成功");
        }
        
        public IActionResult Contact()
        {
            ViewData["Message"] = "Your contact page.";
            return View();
        }
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }
        [AllowAnonymous]
        [HttpGet("login")]
        public IActionResult Login(string returnUrl = null)
        {
            TempData["returnUrl"] = returnUrl;
            return View();
        }
        [AllowAnonymous]
        [HttpPost("login")]
        public async Task<IActionResult> Login(string userName, string password, string returnUrl = null)
        {
            var list = new List<dynamic> {
                new { UserName = "gsw", Password = "111111", Role = "admin",Name="桂素伟",Country="中国",Date="2017-09-02",BirthDay="1979-06-22"},
                new { UserName = "aaa", Password = "222222", Role = "system",Name="测试A" ,Country="美国",Date="2017-09-03",BirthDay="1999-06-22"}
            };
            var user = list.SingleOrDefault(s => s.UserName == userName && s.Password == password);
            if (user != null)
            {
                //用户标识
                var identity = new ClaimsIdentity(CookieAuthenticationDefaults.AuthenticationScheme);
                identity.AddClaim(new Claim(ClaimTypes.Sid, userName));
                identity.AddClaim(new Claim(ClaimTypes.Name, user.Name));
                identity.AddClaim(new Claim(ClaimTypes.Role, user.Role));
                identity.AddClaim(new Claim(ClaimTypes.Country, user.Country));
                identity.AddClaim(new Claim("date", user.Date));
                await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, new ClaimsPrincipal(identity));
                if (returnUrl == null)
                {
                    returnUrl = TempData["returnUrl"]?.ToString();
                }
                if (returnUrl != null)
                {
                    return Redirect(returnUrl);
                }
                else
                {
                    return RedirectToAction(nameof(HomeController.Index), "Home");
                }
            }
            else
            {
                const string badUserNameOrPasswordMessage = "用户名或密码错误！";
                return BadRequest(badUserNameOrPasswordMessage);
            }
        }
        [HttpGet("logout")]
        public async Task<IActionResult> Logout()
        {
            await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
            return RedirectToAction("Index", "Home");
        }
        [AllowAnonymous]
        [HttpGet("denied")]
        public IActionResult Denied()
        {
            return View();
        }
    }
}

本例设计是当用户gsw密码111111登录时，是不能访问/home/contact的，刚登录时访该action是不成功的，这里我们在/home/addpermission中添加一个Action名称:/home/contact，用户名:gsw的信息，此时再访问/home/contact，会发现是可以访问的，这是因为我们热更新了PermissionHandler中的用户权限集合，用户的权限得到了扩展和变化。

其实用中间件能达到灵活权限的设置，用自定义授权Handler也可以，接下来比较一下两种做法的优劣：

最后，把授权策略做了个NuGet的包，大家可在asp.net core 2.0的项目中查询 AuthorizePolicy引用使用这个包，包对应的github地址：https://github.com/axzxs2001/AuthorizePolicy，欢迎大家提出建议，来共同完善这个授权策略。