From 01b7d0dec62ad23f76072b7442a20bfa8604e94d Mon Sep 17 00:00:00 2001
From: Federico Barresi <federico.barresi@ams-osram.com>
Date: Thu, 18 Dec 2025 21:19:05 +0100
Subject: [PATCH] added check access token validity before refresh

---
 .../IdentityModel.OidcClient/RefreshTokenDelegatingHandler.cs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/identity-model-oidc-client/src/IdentityModel.OidcClient/RefreshTokenDelegatingHandler.cs b/identity-model-oidc-client/src/IdentityModel.OidcClient/RefreshTokenDelegatingHandler.cs
index 7dd346483..f902181ed 100644
--- a/identity-model-oidc-client/src/IdentityModel.OidcClient/RefreshTokenDelegatingHandler.cs
+++ b/identity-model-oidc-client/src/IdentityModel.OidcClient/RefreshTokenDelegatingHandler.cs
@@ -20,6 +20,7 @@ public class RefreshTokenDelegatingHandler : DelegatingHandler
     private string _accessToken;
     private string _accessTokenType;
     private string _refreshToken;
+    private DateTime? _validUntil;
 
     private bool _disposed;
 
@@ -120,7 +121,7 @@ public RefreshTokenDelegatingHandler(OidcClient oidcClient, string accessToken,
     protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
     {
         var accessToken = await GetAccessTokenAsync(cancellationToken);
-        if (accessToken.IsMissing())
+        if (accessToken.IsMissing() || (_validUntil.HasValue && _validUntil.Value < DateTime.Now))
         {
             if (await RefreshTokensAsync(cancellationToken) == false)
             {
@@ -182,6 +183,7 @@ private async Task<bool> RefreshTokensAsync(CancellationToken cancellationToken)
                 if (!response.IsError)
                 {
                     _accessToken = response.AccessToken;
+                    _validUntil = DateTime.Now.AddSeconds(response.ExpiresIn);
                     if (!response.RefreshToken.IsMissing())
                     {
                         _refreshToken = response.RefreshToken;