ASP.NET Core中使用自定义验证属性控制访问权限

在应用中，有时我们需要对访问的客户端进行有效性验证，只有提供有效凭证（AccessToken）的终端应用能访问我们的受控站点（如WebAPI站点），此时我们可以通过验证属性的方法来解决。

一、public class Startup的配置：

//启用跨域访问（不同端口也是跨域）
services.AddCors(options =>
{
options.AddPolicy("AllowOriginOtherBis",
builder => builder.WithOrigins("https://1.16.9.12:4432", "https://pc12.ato.biz:4432", "https://localhost:44384", "https://1.16.9.12:4432", "https://pc12.ato.biz:4432").AllowAnyMethod().AllowAnyHeader());
});

//启用自定义属性以便对控制器或Action进行[TerminalApp()]定义。

services.AddSingleton<IAuthorizationHandler, TerminalAppAuthorizationHandler>();
services.AddAuthorization(options =>
{
options.AddPolicy("TerminalApp", policyBuilder =>
{
policyBuilder.Requirements.Add(new TerminalAppAuthorizationRequirement());
});
});

二、public void Configure(IApplicationBuilder app, IHostingEnvironment env)中的配置：

app.UseHttpsRedirection();　　//使用Https传输
app.UseCors("AllowOriginOtherBis"); //根据定义启用跨域设置

三、示例WebApi项目结构：

四、主要代码（我采用的从数据库进行验证）：

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true)]
    internal class TerminalAppAttribute : AuthorizeAttribute
    {
        public string AppID { get; }

        /// <summary>
        /// 指定客户端访问API
        /// </summary>
        /// <param name="appID"></param>
        public TerminalAppAttribute(string appID="") : base("TerminalApp")
        {
            AppID = appID;
        }
    }

    public abstract class AttributeAuthorizationHandler<TRequirement, TAttribute> : AuthorizationHandler<TRequirement> where TRequirement : IAuthorizationRequirement where TAttribute : Attribute
    {
        protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement)
        {
            var attributes = new List<TAttribute>();

            if ((context.Resource as AuthorizationFilterContext)?.ActionDescriptor is ControllerActionDescriptor action)
            {
                attributes.AddRange(GetAttributes(action.ControllerTypeInfo.UnderlyingSystemType));
                attributes.AddRange(GetAttributes(action.MethodInfo));
            }

            return HandleRequirementAsync(context, requirement, attributes);
        }

        protected abstract Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement, IEnumerable<TAttribute> attributes);

        private static IEnumerable<TAttribute> GetAttributes(MemberInfo memberInfo)
        {
            return memberInfo.GetCustomAttributes(typeof(TAttribute), false).Cast<TAttribute>();
        }
    }

    internal class TerminalAppAuthorizationHandler : AttributeAuthorizationHandler<TerminalAppAuthorizationRequirement,TerminalAppAttribute>
    {
        protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, TerminalAppAuthorizationRequirement requirement, IEnumerable<TerminalAppAttribute> attributes)
        {
            object errorMsg = string.Empty;
            //如果取不到身份验证信息，并且不允许匿名访问，则返回未验证403
            if (context.Resource is AuthorizationFilterContext filterContext &&
filterContext.ActionDescriptor is ControllerActionDescriptor descriptor)
            {
                //先判断是否是匿名访问,
                if (descriptor != null)
                {
                    var actionAttributes = descriptor.MethodInfo.GetCustomAttributes(inherit: true);
                    bool isAnonymous = actionAttributes.Any(a => a is AllowAnonymousAttribute);
                    //非匿名的方法,链接中添加accesstoken值
                    if (isAnonymous)
                    {
                        context.Succeed(requirement);
                        return Task.CompletedTask;
                    }
                    else
                    {
                        //url获取access_token
                        //从AuthorizationHandlerContext转成HttpContext，以便取出表求信息
                        var httpContext = (context.Resource as AuthorizationFilterContext).HttpContext;
                        //var questUrl = httpContext.Request.Path.Value.ToLower();
                        string requestAppID = httpContext.Request.Headers["appid"];
                        string requestAccessToken = httpContext.Request.Headers["access_token"];
                        if ((!string.IsNullOrEmpty(requestAppID)) && (!string.IsNullOrEmpty(requestAccessToken)))
                        {
                            if (attributes != null)
                            {
                                //当不指定具体的客户端AppID仅运用验证属性时默认所有客户端都接受
                                if (attributes.ToArray().ToString()=="") 
                                {
                                    //任意一个在数据库列表中的App都可以运行,否则先判断提交的APPID与需要ID是否相符
                                    bool mat = false;
                                    foreach (var terminalAppAttribute in attributes)
                                    {
                                        if (terminalAppAttribute.AppID == requestAppID)
                                        {
                                            mat = true;
                                            break;
                                        }
                                    }
                                    if (!mat)
                                    {
                                        errorMsg = ReturnStd.NotAuthorize("客户端应用未在服务端登记或未被授权运用当前功能.");
                                        return HandleBlockedAsync(context, requirement, errorMsg);
                                    }
                                }
                            }

                            //如果未指定attributes，则表示任何一个终端服务都可以调用服务, 在验证区域验证终端提供的ID是否匹配数据库记录
                            string valRst = ValidateToken(requestAppID, requestAccessToken);
                            if (string.IsNullOrEmpty(valRst))
                            {
                                context.Succeed(requirement);
                                return Task.CompletedTask;
                            }
                            else
                            {
                                errorMsg = ReturnStd.NotAuthorize("AccessToken验证失败(" + valRst + ")","91");
                                return HandleBlockedAsync(context, requirement, errorMsg);
                            }
                        }
                        else
                        {
                            errorMsg = ReturnStd.NotAuthorize("未提供AppID或Token."); 
                            return HandleBlockedAsync(context, requirement, errorMsg);
                            //return Task.CompletedTask;
                        }
                    }
                }
            }
            else
            {
                errorMsg = ReturnStd.NotAuthorize("FilterContext类型不匹配.");
                return HandleBlockedAsync(context, requirement, errorMsg);
            }

            errorMsg = ReturnStd.NotAuthorize("未知错误.");
            return HandleBlockedAsync(context,requirement, errorMsg);
        }


        //校验票据（数据库数据匹配）
        /// <summary>
        /// 验证终端服务程序提供的AccessToken是否合法
        /// </summary>
        /// <param name="appID">终端APP的ID</param>
        /// <param name="accessToken">终端APP利用其自身AppKEY运算出来的AccessToken,与服务器生成的进行比对</param>
        /// <returns></returns>
        private string ValidateToken(string appID,string accessToken)
        {
            try
            {
                DBContextMain dBContext = new DBContextMain();
                string appKeyOnServer = string.Empty;
                //从数据库读取AppID对应的KEY(此KEY为加解密算法的AES_KEY
                AuthApp authApp = dBContext.AuthApps.FirstOrDefault(a => a.AppID == appID);
                if (authApp == null)
                {
                    return "客户端应用没有在云端登记!";
                }
                else
                {
                    appKeyOnServer = authApp.APPKey;
                }
                if (string.IsNullOrEmpty(appKeyOnServer))
                {
                    return "客户端应用基础信息有误!"; 
                }

                string tmpToken = string.Empty;
                tmpToken = System.Net.WebUtility.UrlDecode(accessToken);//解码相应的Token到原始字符(因其中可能会有+=等特殊字符,必须编码后传递)
                tmpToken = OCrypto.AES16Decrypt(tmpToken, appKeyOnServer); //使用APPKEY解密并分析

                if (string.IsNullOrEmpty(tmpToken))
                {
                    return "客户端提交的身份令牌运算为空!";
                }
                else
                {
                    try
                    {
                        //原始验证码为im_cloud_sv001-appid-ticks格式
                        //取出时间,与服务器时间对比,超过10秒即拒绝服务
                        long tmpTime =Convert.ToInt64(tmpToken.Substring(tmpToken.LastIndexOf("-")+1));
                        //DateTime dt = DateTime.ParseExact(tmpTime, "yyyyMMddHHmmss", CultureInfo.CurrentCulture);
                        DateTime dt= new DateTime(tmpTime);
                        bool IsInTimeSpan = (Convert.ToDouble(ODateTime.DateDiffSeconds(dt, DateTime.Now)) <= 7200);
                        bool IsInternalApp = (tmpToken.IndexOf("im_cloud_sv001-") >= 0);
                        if (!IsInternalApp || !IsInTimeSpan)
                        {
                            return "令牌未被许可或已经失效!";
                        }
                        else
                        {
                            return string.Empty; //成功验证
                        }
                    }
                    catch (Exception ex)
                    {
                        return "令牌解析出错(" + ex.Message + ")";
                    }

                }
            }
            catch (Exception ex)
            {
                return "令牌解析出错(" + ex.Message + ")";
            }
        }

        private Task HandleBlockedAsync(AuthorizationHandlerContext context, TerminalAppAuthorizationRequirement requirement, object errorMsg)
        {
            var authorizationFilterContext = context.Resource as AuthorizationFilterContext;
            authorizationFilterContext.Result = new JsonResult(errorMsg) { StatusCode = 202 };
            //设置为403会显示不了自定义信息,改为Accepted202,由客户端处理
            context.Succeed(requirement);
            return Task.CompletedTask;
        }
    }

    internal class TerminalAppAuthorizationRequirement : IAuthorizationRequirement
    {
        public TerminalAppAuthorizationRequirement()
        {
        }
    }

五、相应的Token验证代码：

    [AutoValidateAntiforgeryToken]  //在本控制器内自动启用跨站攻击防护
    [Route("api/get_accesstoken")]
    public class GetAccessTokenController : Controller
    {
        //尚未限制访问频率
        //返回{"access_token":"ACCESS_TOKEN","expires_in":7200} 有效期2个小时
        //错误时返回{"errcode":40013,"errmsg":"invalid appid"}
        [AllowAnonymous]
        public ActionResult<string> Get()
        {
            try
            {
                string tmpToken = string.Empty;

                string appID = HttpContext.Request.Headers["appid"];
                string appKey = HttpContext.Request.Headers["appkey"];

                if ((appID.Length < 5) || appKey.Length != 32)
                {
                    return "{'errcode':10000,'errmsg':'appid或appkey未提供'}";
                }
                //token采用im_cloud_sv001-appid-ticks数字
                long timeTk = DateTime.Now.Ticks; //输出毫微秒：633603924670937500
                                                  //DateTime dt = new DateTime(timeTk);//可以还原时间

                string plToken = "im_cloud1-" + appID + "-" + timeTk;
                tmpToken = OCrypto.AES16Encrypt(plToken, appKey); //使用APPKEY加密

                tmpToken = System.Net.WebUtility.UrlEncode(tmpToken);
                //编码相应的Token(因其中可能会有+=等特殊字符,必须编码后传递)
                tmpToken = "{'access_token':'" + tmpToken + "','expires_in':7200}";
                return tmpToken;
            }
            catch (Exception ex)
            {
                return "{'errcode':10001,'errmsg':'" + ex.Message +"'}";
            }
        }
    }

六、这样，在我们需要控制的地方加上

[TerminalApp()] 即可，这样所有授权的App都能访问，当然，也可以使用[TerminalApp(“app01”)]限定某一个ID为app01的应用访问。

    [Area("SYS")]        // 路由: api/sys/user
    [Produces("application/json")]
    [TerminalApp()]  
    public class UserController : Controller
{
//
}

　

 七、一个CS客户端通过Web API上传数据调用示例：

            string postURL = "http://sv12.ato.com/api/sys/user/postnew";

            Dictionary<string, string> headerDic2 = new Dictionary<string, string>
            {
                { "appid", MainFramework.CloudAppID },
                { "access_token", accessToken }
            };
            string pushRst = OPWeb.Post(postURL, headerDic2, "POST", sYS_Users);
            if (string.IsNullOrEmpty(pushRst))
            {
                MyMsg.Information("推送成功!");
            }
            else
            {
                MyMsg.Information("推送失败!", pushRst);
            }

　　

            string accessToken = MainFramework.CloudAccessToken;
            if (accessToken.IndexOf("ERROR:") >= 0)
            {
                MyMsg.Information("获取Token出错:" + accessToken);
                return;
            }