Azure AD SSO in ASP.NET - How to update token silently? - asp.net

Question

I have a quite simple ASP.NET project that has the Azure AD Authentication installed.
It uses the CookieAuthentication by default and uses the Azure AD SSO to login.
So what I can't understand is that if I login and left the page opened for 1 hour - which is the Azure AD access token expiration time, it just stops working.
To avoid this, I tried to update the access token silently before it is expired but failed.
Not even sure why the app stops working as it's using Cookie for authorization and it uses the Azure AD login only for Authentication.
app.UseCookieAuthentication(new CookieAuthenticationOptions
{
Provider = new CookieAuthenticationProvider
{
OnValidateIdentity = (context) =>
{
var threshold = DateTime.UtcNow.AddMinutes(55);
if (context.Properties.ExpiresUtc < threshold)
{
var authManager = context.OwinContext.Authentication;
string signedInUserID = context.Identity.FindFirst(System.IdentityModel.Claims.ClaimTypes.NameIdentifier).Value;
if (authContext == null)
authContext = new AuthenticationContext(Authority, new ADALTokenCache(signedInUserID));
ClientCredential credential = new ClientCredential(clientId, appKey);
try
{
var result = authContext.AcquireTokenSilentAsync(graphResourceId, clientId).Result;
}
catch (AggregateException ex)
{
if (ex.InnerException.GetType() == typeof(AdalSilentTokenAcquisitionException))
{
var result = authContext.AcquireTokenAsync(graphResourceId, credential).Result;
}
}
}
return Task.FromResult(0);
}
}
});
This is the ADALTokenCache.
public class ADALTokenCache : TokenCache
{
private ApplicationDbContext db = new ApplicationDbContext();
private string userId;
private UserTokenCache Cache;
public ADALTokenCache(string signedInUserId)
{
// Associate the cache to the current user of the web app
userId = signedInUserId;
this.AfterAccess = AfterAccessNotification;
this.BeforeAccess = BeforeAccessNotification;
this.BeforeWrite = BeforeWriteNotification;
// Look up the entry in the database
Cache = db.UserTokenCacheList.FirstOrDefault(c => c.webUserUniqueId == userId);
// Place the entry in memory
this.Deserialize((Cache == null) ? null : MachineKey.Unprotect(Cache.cacheBits,"ADALCache"));
}
// Clean up the database
public override void Clear()
{
base.Clear();
var cacheEntry = db.UserTokenCacheList.FirstOrDefault(c => c.webUserUniqueId == userId);
db.UserTokenCacheList.Remove(cacheEntry);
db.SaveChanges();
}
// Notification raised before ADAL accesses the cache.
// This is your chance to update the in-memory copy from the DB, if the in-memory version is stale
void BeforeAccessNotification(TokenCacheNotificationArgs args)
{
if (Cache == null)
{
// First time access
Cache = db.UserTokenCacheList.FirstOrDefault(c => c.webUserUniqueId == userId);
}
else
{
// Retrieve last write from the DB
var status = from e in db.UserTokenCacheList
where (e.webUserUniqueId == userId)
select new
{
LastWrite = e.LastWrite
};
// If the in-memory copy is older than the persistent copy
if (status.First().LastWrite > Cache.LastWrite)
{
// Read from from storage, update in-memory copy
Cache = db.UserTokenCacheList.FirstOrDefault(c => c.webUserUniqueId == userId);
}
}
this.Deserialize((Cache == null) ? null : MachineKey.Unprotect(Cache.cacheBits, "ADALCache"));
}
// Notification raised after ADAL accessed the cache.
// If the HasStateChanged flag is set, ADAL changed the content of the cache
void AfterAccessNotification(TokenCacheNotificationArgs args)
{
// If state changed
if (this.HasStateChanged)
{
Cache = new UserTokenCache
{
webUserUniqueId = userId,
cacheBits = MachineKey.Protect(this.Serialize(), "ADALCache"),
LastWrite = DateTime.Now
};
// Update the DB and the lastwrite
db.Entry(Cache).State = Cache.UserTokenCacheId == 0 ? EntityState.Added : EntityState.Modified;
db.SaveChanges();
this.HasStateChanged = false;
}
}
void BeforeWriteNotification(TokenCacheNotificationArgs args)
{
// If you want to ensure that no concurrent write take place, use this notification to place a lock on the entry
var t = args;
}
public override void DeleteItem(TokenCacheItem item)
{
base.DeleteItem(item);
}
}
This is what I tried, but not working.
Would appreciate any help.
Thanks in advance.