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。
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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 Login(string userName, string password, string returnUrl = null)
{
var list = new List {
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 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
///
/// 用户权限
///
public class UserPermission
{
///
/// 用户名
///
public string UserName
{ get; set; }
///
/// 请求Url
///
public string Url
{ get; set; }
}
接下来定义一个PermissionRequirement，为请求条件实体类
///
/// 必要参数类
///
public class PermissionRequirement : IAuthorizationRequirement
{
///
/// 用户权限集合
///
public List UserPermissions { get;private set; }
///
/// 无权限action
///
public string DeniedAction { get; set; }
///
/// 构造
///
/// 无权限action
/// 用户权限集合
public PermissionRequirement(string deniedAction, List 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，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
{
///
/// 权限授权Handler
///
public class PermissionHandler : AuthorizationHandler
{
///
/// 用户权限
///
public List 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 {
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();
}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 Login(string userName, string password, string returnUrl = null)
{
var list = new List {
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 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：
| 中间件 | 自定义授权Handler |
用户权限集合 | 静态对象 | 实体化对象 |
热更新时 | 用中间件名称.用户权限集合更新 | 因为在Startup.cs中，PermissionHandler是依赖注放的，可以在热更新的构造中获取并操作 |
性能方面 | 每个action请求都会触发Invock方法，标记[AllowAnonymous]特性的Action也会触发 | 只有标记[Authorize]特性的Action会触发该方法，标记[AllowAnonymous]特性的Action不会触发，性能更优化 |
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。
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