三分鐘學會.NET Core Jwt 策略授權認證
一.前言
大家好我又回來了,前幾天講過一個關於Jwt的身份驗證最簡單的案例,但是功能還是不夠強大,不適用於真正的專案,是的,在真正面對複雜而又苛刻的客戶中,我們會不知所措,就現在需要將認證授權這一塊也變的複雜而又實用起來,那在專業術語中就叫做自定義策略的API認證,本次案例執行在.NET Core 3.0中,最後我們將在swagger中進行瀏覽,來嘗試專案是否正常,對於.NET Core 2.x 版本,這篇文章有些程式碼不適用,但我會在文中說明。
二.在.NET Core中嘗試
我們都知道Jwt是為了認證,微軟給我們提供了進城打鬼子的城門,那就是 AuthorizationHandle。
我們首先要實現它,並且我們還可以根據依賴注入的 AuthorizationHandlerContext 來獲取上下文,就這樣我們就更可以做一些許可權的手腳
public class PolicyHandler : AuthorizationHandler<PolicyRequirement> { protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, PolicyRequirement requirement) { var http = (context.Resource as Microsoft.AspNetCore.Routing.RouteEndpoint); var questUrl = "/"+http.RoutePattern.RawText; //賦值使用者許可權 var userPermissions = requirement.UserPermissions; //是否經過驗證 var isAuthenticated = context.User.Identity.IsAuthenticated; if (isAuthenticated) { if (userPermissions.Any(u=>u.Url == questUrl)) { //使用者名稱 var userName = context.User.Claims.SingleOrDefault(s => s.Type == ClaimTypes.NameIdentifier).Value; if (userPermissions.Any(w => w.UserName == userName)) { context.Succeed(requirement); } } } return Task.CompletedTask; } }
首先,我們重寫了 HandleRequirementAsync 方法,如果你看過AspNetCore的原始碼你一定知道,它是Jwt身份認證的開端,也就是說你重寫了它,原來那一套就不會走了,我們觀察一下原始碼,我貼在下面,可以看到這就是一個最基本的授權,通過 context.Succeed(requirement 完成了最後的認證動作!
public class DenyAnonymousAuthorizationRequirement : AuthorizationHandler<DenyAnonymousAuthorizationRequirement>, IAuthorizationRequirement { /// <summary> /// Makes a decision if authorization is allowed based on a specific requirement. /// </summary> /// <param name="context">The authorization context.</param> /// <param name="requirement">The requirement to evaluate.</param> protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, DenyAnonymousAuthorizationRequirement requirement) { var user = context.User; var userIsAnonymous = user?.Identity == null || !user.Identities.Any(i => i.IsAuthenticated); if (!userIsAnonymous) { context.Succeed(requirement); } return Task.CompletedTask; } }
那麼 Succeed 是一個什麼呢?它是一個在 AuthorizationHandlerContext的定義動作,包括Fail() ,也是如此,當然具體實現我們不在細談,其內部還是挺複雜的,不過我們需要的是 DenyAnonymousAuthorizationRequirement 被當作了抽象的一部分。
public abstract class AuthorizationHandler<TRequirement> : IAuthorizationHandler where TRequirement : IAuthorizationRequirement {}
好吧,言歸正傳(看原始碼挺刺激的),我們剛剛在 PolicyHandler實現了自定義認證策略,上面還說到了兩個方法。現在我們在專案中配置並啟動它,並且我在程式碼中也是用了Swagger用於後面的演示。
在 AddJwtBearer中我們添加了jwt驗證包括了驗證引數以及幾個事件處理,這個很基本,不在解釋。不過在Swagger中新增jwt的一些功能是在 AddSecurityDefinition 中寫入的。
public void ConfigureServices(IServiceCollection services) { //新增策略鑑權模式 services.AddAuthorization(options => { options.AddPolicy("Permission", policy => policy.Requirements.Add(new PolicyRequirement())); }) .AddAuthentication(s => { //新增JWT Scheme s.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme; s.DefaultScheme = JwtBearerDefaults.AuthenticationScheme; s.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme; }) //新增jwt驗證: .AddJwtBearer(options => { options.TokenValidationParameters = new TokenValidationParameters { ValidateLifetime = true,//是否驗證失效時間 ClockSkew = TimeSpan.FromSeconds(30), ValidateAudience = true,//是否驗證Audience //ValidAudience = Const.GetValidudience(),//Audience //這裡採用動態驗證的方式,在重新登陸時,重新整理token,舊token就強制失效了 AudienceValidator = (m, n, z) => { return m != null && m.FirstOrDefault().Equals(Const.ValidAudience); }, ValidateIssuer = true,//是否驗證Issuer ValidIssuer = Const.Domain,//Issuer,這兩項和前面簽發jwt的設定一致 ValidateIssuerSigningKey = true,//是否驗證SecurityKey IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Const.SecurityKey))//拿到SecurityKey }; options.Events = new JwtBearerEvents { OnAuthenticationFailed = context => { //Token expired if (context.Exception.GetType() == typeof(SecurityTokenExpiredException)) { context.Response.Headers.Add("Token-Expired", "true"); } return Task.CompletedTask; } }; }); services.AddSwaggerGen(c => { c.SwaggerDoc("v1", new OpenApiInfo { Version = "v1", Title = "HaoZi JWT", Description = "基於.NET Core 3.0 的JWT 身份驗證", Contact = new OpenApiContact { Name = "zaranet", Email = "[email protected]", Url = new Uri("http://cnblogs.com/zaranet"), }, }); c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme() { Description = "在下框中輸入請求頭中需要新增Jwt授權Token:Bearer Token", Name = "Authorization", In = ParameterLocation.Header, Type = SecuritySchemeType.ApiKey, BearerFormat = "JWT", Scheme = "Bearer" }); c.AddSecurityRequirement(new OpenApiSecurityRequirement { { new OpenApiSecurityScheme { Reference = new OpenApiReference { Type = ReferenceType.SecurityScheme, Id = "Bearer" } }, new string[] { } } }); }); //認證服務 services.AddSingleton<IAuthorizationHandler, PolicyHandler>(); services.AddControllers(); }
在以上程式碼中,我們通過鑑權模式添加了認證規則,一個名叫 PolicyRequirement 的類,它實現了 IAuthorizationRequirement 介面,其中我們需要定義一些規則,通過建構函式我們可以新增我們要識別的許可權規則。那個UserName就是 Attribute 。
public class PolicyRequirement : IAuthorizationRequirement {/// <summary> /// User rights collection /// </summary> public List<UserPermission> UserPermissions { get; private set; } /// <summary> /// No permission action /// </summary> public string DeniedAction { get; set; } /// <summary> /// structure /// </summary> public PolicyRequirement() { //Jump to this route without permission DeniedAction = new PathString("/api/nopermission"); //Route configuration that users have access to, of course you can read it from the database, you can also put it in Redis for persistence UserPermissions = new List<UserPermission> { new UserPermission { Url="/api/value3", UserName="admin"}, }; } } public class UserPermission { public string UserName { get; set; } public string Url { get; set; } }
隨後我們應當啟動我們的服務,在.NET Core 3.0 中身份驗證的中介軟體位置需要在路由和端點配置的中間。
public void Configure(IApplicationBuilder app, IWebHostEnvironment env) { if (env.IsDevelopment()) { app.UseDeveloperExceptionPage(); } app.UseSwagger(); app.UseSwaggerUI(c => { c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1"); }); app.UseRouting(); app.UseAuthentication(); app.UseAuthorization(); app.UseEndpoints(endpoints => { endpoints.MapControllers(); }); }
我們通常會有一個獲取token的API,用於讓Jwt通過 JwtSecurityTokenHandler().WriteToken(token) 用於生成我們的token,雖然jwt是沒有狀態的,但你應該也明白,如果你的jwt生成了隨後你重啟了你的網站,你的jwt會失效,這個是因為你的金鑰進行了改變,如果你的金鑰一直寫死,那麼這個jwt將不會再過期,這個還是有安全風險的,這個我不在這裡解釋,gettoken定義如下:
[ApiController] public class AuthController : ControllerBase { [AllowAnonymous] [HttpGet] [Route("api/nopermission")] public IActionResult NoPermission() { return Forbid("No Permission!"); } /// <summary> /// login /// </summary> [AllowAnonymous] [HttpGet] [Route("api/auth")] public IActionResult Get(string userName, string pwd) { if (CheckAccount(userName, pwd, out string role)) { Const.ValidAudience = userName + pwd + DateTime.Now.ToString(); // push the user’s name into a claim, so we can identify the user later on. //這裡可以隨意加入自定義的引數,key可以自己隨便起 var claims = new[] { new Claim(JwtRegisteredClaimNames.Nbf,$"{new DateTimeOffset(DateTime.Now).ToUnixTimeSeconds()}") , new Claim (JwtRegisteredClaimNames.Exp,$"{new DateTimeOffset(DateTime.Now.AddMinutes(30)).ToUnixTimeSeconds()}"), new Claim(ClaimTypes.NameIdentifier, userName), new Claim("Role", role) }; //sign the token using a secret key.This secret will be shared between your API and anything that needs to check that the token is legit. var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Const.SecurityKey)); var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256); //.NET Core’s JwtSecurityToken class takes on the heavy lifting and actually creates the token. var token = new JwtSecurityToken( issuer: Const.Domain, //頒發者 audience: Const.ValidAudience,//過期時間 expires: DateTime.Now.AddMinutes(30),// 簽名證書 signingCredentials: creds, //自定義引數 claims: claims ); return Ok(new { token = new JwtSecurityTokenHandler().WriteToken(token) }); } else { return BadRequest(new { message = "username or password is incorrect." }); } } /// <summary> /// 模擬登陸校驗 /// </summary> private bool CheckAccount(string userName, string pwd, out string role) { role = "user"; if (string.IsNullOrEmpty(userName)) return false; if (userName.Equals("admin")) role = "admin"; return true; }
可能比較特別的是 AllowAnonymous ,這個看我文章的同學可能頭一次見,其實怎麼說好呢,這個可無可有,沒有硬性的要求,我看到好幾個知名博主加上了,我也加上了~...最後我們建立了幾個資源控制器,它們是受保護的。
在你新增策略許可權的時候例如政策名稱是XXX,那麼在對應的api表頭就應該是XXX,隨後到了 PolicyHandler我們解析了 Claims 處理了它是否有許可權。
// GET api/values1 [HttpGet] [Route("api/value1")] public ActionResult<IEnumerable<string>> Get() { return new string[] { "value1", "value1" }; } // GET api/values2 /** * 該介面用Authorize特性做了許可權校驗,如果沒有通過許可權校驗,則http返回狀態碼為401 */ [HttpGet] [Route("api/value2")] [Authorize] public ActionResult<IEnumerable<string>> Get2() { var auth = HttpContext.AuthenticateAsync().Result.Principal.Claims; var userName = auth.FirstOrDefault(t => t.Type.Equals(ClaimTypes.NameIdentifier))?.Value; return new string[] { "這個介面登陸過的都能訪問", $"userName={userName}" }; } /** * 這個介面必須用admin **/ [HttpGet] [Route("api/value3")] [Authorize("Permission")] public ActionResult<IEnumerable<string>> Get3() { //這是獲取自定義引數的方法 var auth = HttpContext.AuthenticateAsync().Result.Principal.Claims; var userName = auth.FirstOrDefault(t => t.Type.Equals(ClaimTypes.NameIdentifier))?.Value; var role = auth.FirstOrDefault(t => t.Type.Equals("Role"))?.Value; return new string[] { "這個介面有管理員許可權才可以訪問", $"userName={userName}", $"Role={role}" }; }
三.效果圖
四.栗子原始碼和以往版本
看到很多前輩彩的坑,原來的 (context.Resource as Microsoft.AspNetCore.Routing.RouteEndpoint); 實際上在.NET Core 3.0 已經不能用了,原因是.NET Core 3.0 啟用 EndpointRouting 後,許可權filter不再新增到 ActionDescriptor ,而將許可權直接作為中介軟體執行,同時所有filter都會新增到 endpoint.Metadata ,如果在.NET Core 2.1 & 2.2 版本中你通常Handler可以這麼寫:
public class PolicyHandler : AuthorizationHandler<PolicyRequirement> { protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, PolicyRequirement requirement) { //賦值使用者許可權 var userPermissions = requirement.UserPermissions; //從AuthorizationHandlerContext轉成HttpContext,以便取出表求資訊 var httpContext = (context.Resource as Microsoft.AspNetCore.Mvc.Filters.AuthorizationFilterContext).HttpContext; //請求Url var questUrl = httpContext.Request.Path.Value.ToUpperInvariant(); //是否經過驗證 var isAuthenticated = httpContext.User.Identity.IsAuthenticated; if (isAuthenticated) { if (userPermissions.GroupBy(g => g.Url).Any(w => w.Key.ToUpperInvariant() == questUrl)) { //使用者名稱 var userName = httpContext.User.Claims.SingleOrDefault(s => s.Type == ClaimTypes.NameIdentifier).Value; if (userPermissions.Any(w => w.UserName == userName && w.Url.ToUpperInvariant() == questUrl)) { context.Succeed(requirement); } else { //無許可權跳轉到拒絕頁面 httpContext.Response.Redirect(requirement.DeniedAction); } } else context.Succeed(requirement); } return Task.CompletedTask; } }
該案例原始碼在我的Github上:https://github.com/zaranetCore/aspNetCore_JsonwebToken/tree/master/Jwt_Policy_Demo 謝謝大家