Expired token after some time.

To handle the issue of the token expiring after 5 minutes, you need to implement a mechanism to refresh the token before it expires. This can be achieved by using the Google API client library for .NET.

Here's an example of how you can modify your code to refresh the token:

public async Task OnGetLinkLoginCallbackAsync(SMTPProviderDetails sMTPProviderDetails)
{
    // Existing code...

    // Get the refresh token
    var refreshToken = info.AuthenticationTokens.FirstOrDefault(t => t.Name == "refresh_token")?.Value;

    // Create a new instance of the Google API client
    var client = new Google.Apis.Auth.OAuth2.GoogleCredential
    {
        AccessToken = info.AuthenticationTokens.FirstOrDefault(t => t.Name == "access_token")?.Value,
        RefreshToken = refreshToken
    }.CreateScoped(new[] { "https://www.googleapis.com/auth/userinfo.email" });

    // Check if the access token is about to expire
    if (client.Token.ExpiresInSeconds <= 300) // 300 seconds = 5 minutes
    {
        // Refresh the access token
        await client.RefreshTokenAsync(CancellationToken.None);

        // Update the existing record with the new access token
        existingRecord.SMTPPassword = client.Token.AccessToken;
        existingRecord.UpdateOn = DateTime.UtcNow;
    }

    // Existing code...

    await _context.SaveChangesAsync();
    return RedirectToPage();
}

we retrieve the refresh token from the authentication tokens obtained from Google. We then create a new instance of the Google API client and set the access token and refresh token. We check if the access token is about to expire (within 5 minutes) and if so, we refresh the token using the RefreshTokenAsync method. Finally, we update the existing record with the new access token.

By implementing this token refresh mechanism, you can ensure that the token does not expire and the user can continue to use the Google Authentication without interruption.

This is my code

 

public async Task OnPostLoginAsync(string provider)
        {
            await HttpContext.SignOutAsync(IdentityConstants.ExternalScheme);
            var redirectUrl = Url.Page(".SmtpSetting", pageHandler: "LinkLoginCallback");
            var properties = _signInManager.ConfigureExternalAuthenticationProperties(provider, redirectUrl, _userManager.GetUserId(User));
            return new ChallengeResult(provider, properties);
        }
        public async Task OnGetLinkLoginCallbackAsync(SMTPProviderDetails sMTPProviderDetails)
        {        
            var user = await _userManager.GetUserAsync(User);
            if (user == null)
            {
                return NotFound($"Unable to load user with ID 'user.Id'.");
            }
            var info = await _inManager.GetExternalLoginInfoAsync(user.Id.ToString());
            var emailClaim = info.Principal.Claims.FirstOrDefault(c => c.Type == "emailaddress");
            if (info == null)
            {
                throw new InvalidOperationException($"Unexpected error occurred loading external login info for user with ID '{user.Id.ToString()}'.");
            }
            var existingRecord = await _context.SMTPProviderDetails.FirstOrDefaultAsync(x => x.UserId == user.Id);
            if (existingRecord != null)
            {
                // Update existing record
                existingRecord.SMTPPassword = info.AuthenticationTokens.FirstOrDefault(t => t.Name == "access_token")?.Value;              
                existingRecord.UpdateOn = DateTime.UtcNow;
                if (emailClaim != null)
                {                    
                    existingRecord.UserEmail = emailClaim.Value;
                }                           
            }
            else
            {
                // Insert new record
                sMTPProviderDetails.CreatedOn = DateTime.UtcNow;
                if (emailClaim != null)
                {
                    sMTPProviderDetails.UserEmail = emailClaim.Value;
                }
                sMTPProviderDetails.UserId = Convert.ToInt32(user.Id);
                sMTPProviderDetails.UserName = user.FirstName;
                sMTPProviderDetails.SMTPPassword = info.AuthenticationTokens.FirstOrDefault(t => t.Name == "access_token")?.Value;
                _context.Add(sMTPProviderDetails);
            }
            await _context.SaveChangesAsync();
            return RedirectToPage();
        }