如何知道OWIN Cookie何时到期？

Question

我想基于OWIN Cookie到期的时间创建某种倒数计时器。我将OWIN与MVC 5配合使用，据我了解，SlidingExpiration默认情况下处于启用状态。我不使用“会话”，因为我需要此应用程序驻留在Web场中（我不打算部署会话数据库）。

Answer 1

您需要做的是在cookie验证阶段获得CookieValidateIdentityContext的控制权。一旦获得，请提取所需的任何内容，并将其保留为Claim或您喜欢的其他方式。

对于带有Asp.NET Identity 2.0的MVC 5，您需要执行两个步骤：

1. 定义自定义OnValidateIdentity，提取Cookie信息，并将其保留为Claim。

   public class Startup
   {
     public void Configuration(IAppBuilder app)
     {
       app.UseCookieAuthentication(new CookieAuthenticationOptions
       {
         AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
         Provider = new CookieAuthenticationProvider
         {
           OnValidateIdentity = MyCustomValidateIdentity //refer to the implementation below
         }
       }
     }
   
   
     // this method will be called on every request
     // it is also one of the few places where you can access unencrypted cookie content as CookieValidateIdentityContext
     // once you get cookie information you need, keep it as one of the Claims
     // please ignore the MyUserManager and MyUser classes, they are only for sample, you should have yours
     private static Task MyCustomValidateIdentity(CookieValidateIdentityContext context)
     {
       // validate security stamp for 'sign out everywhere'
       // here I want to verify the security stamp in every 100 seconds.
       // but I choose not to regenerate the identity cookie, so I passed in NULL 
       var stampValidator = SecurityStampValidator.OnValidateIdentity<MyUserManager<Myuser>. MyUser>(TimeSpan.FromSeconds(100), null); 
       stampValidator.Invoke(context);
   
       // here we get the cookie expiry time
       var expireUtc = context.Properties.ExpiresUtc;
   
       // add the expiry time back to cookie as one of the claims, called 'myExpireUtc'
       // to ensure that the claim has latest value, we must keep only one claim
       // otherwise we will be having multiple claims with same type but different values
       var claimType = "myExpireUtc";
       var identity = context.Identity;
       if(identity.HasClaim(c=> c.Type == claimType))
       {
         var existingClaim = identity.FindFirst(claimType);
         identity.RemoveClaim(existingClaim); 
       }
       var newClaim = new Claim(claimType, expireUtc.Value.UtcTicks.ToString());
       context.Identity.AddClaim(newClaim);
   
       return Task.FromResult(0);
     }
   }
   

2. [在控制器方法中访问Claim

   // since expiry time has now become part of your claims, you now can get it back easily
   // this example just returns the remaining time in total seconds, as a string value
   // assuming this method is part of your controller methods
   
   public string RemainingTime()
   {
     var identity = User.Identity as ClaimsIdentity;
     var claimType = "myExpireUtc";  //NOTE: must be the same key value "myExpireUtc" defined in code shown above
   
     if(identity != null && identity.HasClaim(c=> c.Type == claimType))
     { 
       var expireOn = identity.FindFirstValue(claimType); 
   
       DateTimeOffset currentUtc = DateTimeOffset.UtcNow;
       DateTimeOffset? expireUtc = new DateTimeOffset(long.Parse(expireOn), TimeSpan.Zero);
   
       var remaining = (expireUtc.Value - currentUtc).TotalSeconds;
   
       return remaining.ToString();
     }
     return string.Empty;
   }
   

我使用这种方法来提醒我的应用程序用户在会话超时之前延长其会话。

此帖子的信用How do I access Microsoft.Owin.Security.xyz OnAuthenticated context AddClaims values?

Answer 2

我只想以第一个答案为基础，因为使用自定义用户存储时，我无法使其正常工作。尽管对我来说实现似乎更简单

public static class ApplicationCookieValidateIdentityContext
    {
        public static Task ApplicationValidateIdentity(CookieValidateIdentityContext context)
        {          
            var identity = context.Identity;

            if (identity.HasClaim(c => c.Type ==  "expires"))
            {
                var existingClaim = identity.FindFirst( "expires");
                identity.RemoveClaim(existingClaim);
            }

            if (context.Properties.ExpiresUtc == null) return Task.FromResult(0);

            context.Identity.AddClaim(new Claim("expires", context.Properties.ExpiresUtc.ToString()));

            return Task.FromResult(0);
        }
    }

我还创建了一个将过期时间添加到cookie的过滤器

// make sure its defaulted because the claim is not set on the login callback
var expires = DateTimeOffset.Now.AddMinutes(
    Convert.ToDouble(ConfigurationManager.AppSettings["SessionTimeInMinutes"]));


if (identity.HasClaim(c => c.Type == "expires"))
{
    expires = DateTimeOffset.Parse(identity.FindFirstValue("expires"));
}

cookieHeaderValues.Add(new SessionCookeHeaderValue("expiresAt", expires.ToString("O"), expires));