v3 - inject HttpClient, JWT expiration handling, removed IDisposable

Author: andrei-m-code

CorePush/Apple/ApnSender.cs

@@ -3,6 +3,7 @@
 using Org.BouncyCastle.Crypto.Parameters;
 using Org.BouncyCastle.Security;
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Net.Http;
 using System.Security.Cryptography;
@@ -16,39 +17,27 @@ namespace CorePush.Apple
     /// </summary>
     public class ApnSender : IApnSender
     {
+        private static readonly ConcurrentDictionary<string, Tuple<string, DateTime>> tokens = new ConcurrentDictionary<string, Tuple<string, DateTime>>();
         private static readonly Dictionary<ApnServerType, string> servers = new Dictionary<ApnServerType, string>
         {
             {ApnServerType.Development, "https://api.development.push.apple.com:443" },
             {ApnServerType.Production, "https://api.push.apple.com:443" }
         };
 
         private const string apnidHeader = "apns-id";
+        private const int tokenExpiresMinutes = 50;
 
-        private readonly string p8privateKey;
-        private readonly string p8privateKeyId;
-        private readonly string teamId;
-        private readonly string appBundleIdentifier;
-        private readonly ApnServerType server;
-        private readonly Lazy<string> jwtToken;
-        private readonly Lazy<HttpClient> http;
+        private readonly ApnSettings settings;
+        private readonly HttpClient http;
 
         /// <summary>
-        /// Initialize sender
+        /// Apple push notification sender constructor
         /// </summary>
-        /// <param name="p8privateKey">p8 certificate string</param>
-        /// <param name="privateKeyId">10 digit p8 certificate id. Usually a part of a downloadable certificate filename</param>
-        /// <param name="teamId">Apple 10 digit team id</param>
-        /// <param name="appBundleIdentifier">App slug / bundle name</param>
-        /// <param name="server">Development or Production server</param>
-        public ApnSender(string p8privateKey, string p8privateKeyId, string teamId, string appBundleIdentifier, ApnServerType server)
+        /// <param name="settings">Apple Push Notification settings</param>
+        public ApnSender(ApnSettings settings, HttpClient http)
         {
-            this.p8privateKey = p8privateKey;
-            this.p8privateKeyId = p8privateKeyId;
-            this.teamId = teamId;
-            this.server = server;
-            this.appBundleIdentifier = appBundleIdentifier;
-            this.jwtToken = new Lazy<string>(() => CreateJwtToken());
-            this.http = new Lazy<HttpClient>(() => new HttpClient());
+            this.settings = settings ?? throw new ArgumentNullException(nameof(settings));
+            this.http = http ?? throw new ArgumentNullException(nameof(http));
         }
 
         /// <summary>
@@ -70,15 +59,15 @@ public async Task<ApnsResponse> SendAsync(
             var path = $"/3/device/{deviceToken}";
             var json = JsonHelper.Serialize(notification);
 
-            var request = new HttpRequestMessage(HttpMethod.Post, new Uri(servers[server] + path))
+            var request = new HttpRequestMessage(HttpMethod.Post, new Uri(servers[settings.ServerType] + path))
             {
                 Version = new Version(2, 0),
                 Content = new StringContent(json)
             };
-            request.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("bearer", jwtToken.Value);
+            request.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("bearer", GetJwtToken());
             request.Headers.TryAddWithoutValidation(":method", "POST");
             request.Headers.TryAddWithoutValidation(":path", path);
-            request.Headers.Add("apns-topic", appBundleIdentifier);
+            request.Headers.Add("apns-topic", settings.AppBundleIdentifier);
             request.Headers.Add("apns-expiration", apnsExpiration.ToString());
             request.Headers.Add("apns-priority", apnsPriority.ToString());
             request.Headers.Add("apns-push-type", isBackground ? "background" : "alert"); // for iOS 13 required
@@ -87,7 +76,7 @@ public async Task<ApnsResponse> SendAsync(
                 request.Headers.Add(apnidHeader, apnsId);
             }
 
-            using var response = await http.Value.SendAsync(request);
+            using var response = await http.SendAsync(request);
             var succeed = response.IsSuccessStatusCode;
             var content = await response.Content.ReadAsStringAsync();
             var error = JsonHelper.Deserialize<ApnsError>(content);
@@ -99,15 +88,27 @@ public async Task<ApnsResponse> SendAsync(
             };
         }
 
+        private string GetJwtToken()
+        {
+            var (token, date) = tokens.GetOrAdd(settings.AppBundleIdentifier, _ => new Tuple<string, DateTime>(CreateJwtToken(), DateTime.UtcNow));
+            if (date < DateTime.UtcNow.AddMinutes(-tokenExpiresMinutes))
+            {
+                tokens.TryRemove(settings.AppBundleIdentifier, out _);
+                return GetJwtToken();
+            }
+
+            return token;
+        }
+
         private string CreateJwtToken()
         {
-            var header = JsonHelper.Serialize(new { alg = "ES256", kid = p8privateKeyId });
-            var payload = JsonHelper.Serialize(new { iss = teamId, iat = ToEpoch(DateTime.UtcNow) });
+            var header = JsonHelper.Serialize(new { alg = "ES256", kid = settings.P8PrivateKeyId });
+            var payload = JsonHelper.Serialize(new { iss = settings.TeamId, iat = ToEpoch(DateTime.UtcNow) });
             var headerBase64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(header));
             var payloadBasae64 = Convert.ToBase64String(Encoding.UTF8.GetBytes(payload));
             var unsignedJwtData = $"{headerBase64}.{payloadBasae64}";
             var unsignedJwtBytes = Encoding.UTF8.GetBytes(unsignedJwtData);
-            using var dsa = GetEllipticCurveAlgorithm(p8privateKey);
+            using var dsa = GetEllipticCurveAlgorithm(settings.P8PrivateKey);
             var signature = dsa.SignData(unsignedJwtBytes, 0, unsignedJwtBytes.Length, HashAlgorithmName.SHA256);
 
             return $"{unsignedJwtData}.{Convert.ToBase64String(signature)}";
@@ -119,20 +120,11 @@ private static int ToEpoch(DateTime time)
             return Convert.ToInt32(span.TotalSeconds);
         }
 
-        public void Dispose()
-        {
-            if (http.IsValueCreated)
-            {
-                http.Value.Dispose();
-            }
-        }
-
+        // TODO: I'd like to get rid of BouncyCastle dependency...
         // Needed to run on docker linux: ECDsa.Create("ECDsaCng") would generate PlatformNotSupportedException: Windows Cryptography Next Generation (CNG) is not supported on this platform.
         private static ECDsa GetEllipticCurveAlgorithm(string privateKey)
         {
-            var keyParams = (ECPrivateKeyParameters) PrivateKeyFactory
-                .CreateKey(Convert.FromBase64String(privateKey));
-
+            var keyParams = (ECPrivateKeyParameters) PrivateKeyFactory.CreateKey(Convert.FromBase64String(privateKey));
             var q = keyParams.Parameters.G.Multiply(keyParams.D).Normalize();
 
             return ECDsa.Create(new ECParameters

CorePush/Apple/ApnSettings.cs

@@ -0,0 +1,30 @@
+namespace CorePush.Apple
+{
+    public class ApnSettings
+    {
+        /// <summary>
+        /// p8 certificate string
+        /// </summary>
+        public string P8PrivateKey { get; set; }
+
+        /// <summary>
+        /// 10 digit p8 certificate id. Usually a part of a downloadable certificate filename
+        /// </summary>
+        public string P8PrivateKeyId { get; set; } 
+
+        /// <summary>
+        /// Apple 10 digit team id
+        /// </summary>
+        public string TeamId { get; set; }
+
+        /// <summary>
+        /// App slug / bundle name
+        /// </summary>
+        public string AppBundleIdentifier { get; set; }
+
+        /// <summary>
+        /// Development or Production server
+        /// </summary>
+        public ApnServerType ServerType { get; set; }
+    }
+}

CorePush/CorePush.csproj

@@ -6,13 +6,22 @@
     <Authors>Andrei M</Authors>
     <Company />
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-    <AssemblyVersion>2.1.2.0</AssemblyVersion>
-    <FileVersion>2.1.2.0</FileVersion>
-    <Version>2.1.2</Version>
+    <AssemblyVersion>3.0.0.0</AssemblyVersion>
+    <FileVersion>3.0.0.0</FileVersion>
+    <Version>3.0.0</Version>
     <PackageProjectUrl>https://github.com/andrei-m-code/CorePush</PackageProjectUrl>
     <PackageLicenseUrl />
     <PackageReleaseNotes>
+v3.0.0 [Includes breaking changes]
+- Added ApnSettings and FcmSettings
+- HttpClient has to be injected for FcmSender and ApnSender
+- Both ApnSender and FcmSender are not IDisposable anymore as HttpClient is injected and managed outside
+- ApnSender JWT token expiration is managed according to Apple documentation
+
+v2.1.2
 - Added IFcmSender and IApnSender interfaces
+
+Previous Versions: 
 - Requires .NET Core 3.1
 - Target framework changed to netstandard2.1
 - Docker/Linux support is added, thanks to @JeroenBer

CorePush/Google/FcmSender.cs

@@ -14,14 +14,13 @@ namespace CorePush.Google
     public class FcmSender : IFcmSender
     {
         private readonly string fcmUrl = "https://fcm.googleapis.com/fcm/send";
-        private readonly string serverKey;
-        private readonly string senderId;
-        private readonly Lazy<HttpClient> lazyHttp = new Lazy<HttpClient>();
+        private readonly FcmSettings settings;
+        private readonly HttpClient http;
 
-        public FcmSender(string serverKey, string senderId)
+        public FcmSender(FcmSettings settings, HttpClient http)
         {
-            this.serverKey = serverKey;
-            this.senderId = senderId;
+            this.settings = settings;
+            this.http = http;
         }
 
         /// <summary>
@@ -41,22 +40,14 @@ public async Task<FcmResponse> SendAsync(string deviceId, object payload)
             var json = jsonObject.ToString();
 
             using var httpRequest = new HttpRequestMessage(HttpMethod.Post, fcmUrl);
-            httpRequest.Headers.Add("Authorization", $"key = {serverKey}");
-            httpRequest.Headers.Add("Sender", $"id = {senderId}");
+            httpRequest.Headers.Add("Authorization", $"key = {settings.ServerKey}");
+            httpRequest.Headers.Add("Sender", $"id = {settings.SenderId}");
             httpRequest.Content = new StringContent(json, Encoding.UTF8, "application/json");
-            using var response = await lazyHttp.Value.SendAsync(httpRequest);
+            using var response = await http.SendAsync(httpRequest);
             response.EnsureSuccessStatusCode();
             var responseString = await response.Content.ReadAsStringAsync();
 
             return JsonHelper.Deserialize<FcmResponse>(responseString);
         }
-
-        public void Dispose()
-        {
-            if (lazyHttp.IsValueCreated)
-            {
-                lazyHttp.Value.Dispose();
-            }
-        }
     }
 }

CorePush/Google/FcmSettings.cs

@@ -0,0 +1,15 @@
+namespace CorePush.Google
+{
+    public class FcmSettings
+    {
+        /// <summary>
+        /// FCM Sender ID
+        /// </summary>
+        public string SenderId { get; set; }
+
+        /// <summary>
+        /// FCM Server Key
+        /// </summary>
+        public string ServerKey { get; set; }
+    }
+}

CorePush/Interfaces/IApnSender.cs

@@ -4,7 +4,7 @@
 
 namespace CorePush.Interfaces
 {
-    public interface IApnSender : IDisposable
+    public interface IApnSender
     {
         Task<ApnsResponse> SendAsync(
             object notification,

CorePush/Interfaces/IFcmSender.cs

@@ -1,10 +1,9 @@
-using System;
 using System.Threading.Tasks;
 using CorePush.Google;
 
 namespace CorePush.Interfaces
 {
-    public interface IFcmSender : IDisposable
+    public interface IFcmSender
     {
         Task<FcmResponse> SendAsync(string deviceId, object payload);
     }