Allow Vapid header to include expiration.

Author: coryjthompson

WebPush.Test/VapidHelperTest.cs

@@ -41,8 +41,8 @@ public void TestGenerateVapidKeysNoCache()
         public void TestGetVapidHeaders()
         {
             var publicKey = TestPublicKey;
-            var privatekey = TestPrivateKey;
-            var headers = VapidHelper.GetVapidHeaders(ValidAudience, ValidSubject, publicKey, privatekey);
+            var privateKey = TestPrivateKey;
+            var headers = VapidHelper.GetVapidHeaders(ValidAudience, ValidSubject, publicKey, privateKey);
 
             Assert.IsTrue(headers.ContainsKey(@"Authorization"));
             Assert.IsTrue(headers.ContainsKey(@"Crypto-Key"));
@@ -52,54 +52,68 @@ public void TestGetVapidHeaders()
         public void TestGetVapidHeadersAudienceNotAUrl()
         {
             var publicKey = TestPublicKey;
-            var privatekey = TestPrivateKey;
+            var privateKey = TestPrivateKey;
             Assert.ThrowsException<ArgumentException>(
                 delegate
                 {
-                    VapidHelper.GetVapidHeaders("invalid audience", ValidSubjectMailto, publicKey, privatekey);
+                    VapidHelper.GetVapidHeaders("invalid audience", ValidSubjectMailto, publicKey, privateKey);
                 });
         }
 
         [TestMethod]
         public void TestGetVapidHeadersInvalidPrivateKey()
         {
             var publicKey = UrlBase64.Encode(new byte[65]);
-            var privatekey = UrlBase64.Encode(new byte[1]);
+            var privateKey = UrlBase64.Encode(new byte[1]);
 
             Assert.ThrowsException<ArgumentException>(
-                delegate { VapidHelper.GetVapidHeaders(ValidAudience, ValidSubject, publicKey, privatekey); });
+                delegate { VapidHelper.GetVapidHeaders(ValidAudience, ValidSubject, publicKey, privateKey); });
         }
 
         [TestMethod]
         public void TestGetVapidHeadersInvalidPublicKey()
         {
             var publicKey = UrlBase64.Encode(new byte[1]);
-            var privatekey = UrlBase64.Encode(new byte[32]);
+            var privateKey = UrlBase64.Encode(new byte[32]);
 
             Assert.ThrowsException<ArgumentException>(
-                delegate { VapidHelper.GetVapidHeaders(ValidAudience, ValidSubject, publicKey, privatekey); });
+                delegate { VapidHelper.GetVapidHeaders(ValidAudience, ValidSubject, publicKey, privateKey); });
         }
 
         [TestMethod]
         public void TestGetVapidHeadersSubjectNotAUrlOrMailTo()
         {
             var publicKey = TestPublicKey;
-            var privatekey = TestPrivateKey;
+            var privateKey = TestPrivateKey;
 
             Assert.ThrowsException<ArgumentException>(
-                delegate { VapidHelper.GetVapidHeaders(ValidAudience, @"invalid subject", publicKey, privatekey); });
+                delegate { VapidHelper.GetVapidHeaders(ValidAudience, @"invalid subject", publicKey, privateKey); });
         }
 
         [TestMethod]
         public void TestGetVapidHeadersWithMailToSubject()
         {
             var publicKey = TestPublicKey;
-            var privatekey = TestPrivateKey;
+            var privateKey = TestPrivateKey;
             var headers = VapidHelper.GetVapidHeaders(ValidAudience, ValidSubjectMailto, publicKey,
-                privatekey);
+                privateKey);
 
             Assert.IsTrue(headers.ContainsKey(@"Authorization"));
             Assert.IsTrue(headers.ContainsKey(@"Crypto-Key"));
         }
+
+        [TestMethod]
+        public void TestExpirationInPastExceptions()
+        {
+            var publicKey = TestPublicKey;
+            var privateKey = TestPrivateKey;
+
+            Assert.ThrowsException<ArgumentException>(
+                delegate
+                {
+                    VapidHelper.GetVapidHeaders(ValidAudience, ValidSubjectMailto, publicKey,
+                        privateKey, 1552715607);
+                });
+        }
     }
 }

WebPush/Model/VapidDetails.cs

@@ -19,5 +19,7 @@ public VapidDetails(string subject, string publicKey, string privateKey)
         public string Subject { get; set; }
         public string PublicKey { get; set; }
         public string PrivateKey { get; set; }
+
+        public long Expiration { get; set; } = -1;
     }
 }

WebPush/VapidHelper.cs

@@ -48,6 +48,11 @@ public static Dictionary<string, string> GetVapidHeaders(string audience, string
             {
                 expiration = UnixTimeNow() + 43200;
             }
+            else
+            {
+                ValidateExpiration(expiration);                
+            }
+
 
             var header = new Dictionary<string, object> {{"typ", "JWT"}, {"alg", "ES256"}};
 
@@ -136,6 +141,14 @@ public static void ValidatePrivateKey(string privateKey)
             }
         }
 
+        private static void ValidateExpiration(long expiration)
+        {
+            if (expiration <= UnixTimeNow())
+            {
+                throw new ArgumentException(@"Vapid expiration must be a unix timestamp in the future");
+            }
+        }
+
         private static long UnixTimeNow()
         {
             var timeSpan = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0);

WebPush/WebPushClient.cs

@@ -230,7 +230,7 @@ public HttpRequestMessage GenerateRequestDetails(PushSubscription subscription,
                 var audience = uri.Scheme + @"://" + uri.Host;
 
                 var vapidHeaders = VapidHelper.GetVapidHeaders(audience, currentVapidDetails.Subject,
-                    currentVapidDetails.PublicKey, currentVapidDetails.PrivateKey);
+                    currentVapidDetails.PublicKey, currentVapidDetails.PrivateKey, currentVapidDetails.Expiration);
                 request.Headers.Add(@"Authorization", vapidHeaders["Authorization"]);
                 if (string.IsNullOrEmpty(cryptoKeyHeader))
                 {