Attempt to add Google Cloud Platform as a MQTT server

.gitignore

@@ -1,3 +1,4 @@
+NucuCar.Sensors/Certificates/*
 bin/
 obj/
 /packages/

NucuCar.Sensors/NucuCar.Sensors.csproj

@@ -8,8 +8,11 @@
     <ItemGroup>
         <PackageReference Include="Grpc.AspNetCore" Version="2.25.0" />
         <PackageReference Include="Iot.Device.Bindings" Version="1.0.0" />
+        <PackageReference Include="jose-jwt" Version="2.5.0" />
         <PackageReference Include="libgrpc_csharp_ext.arm7" Version="1.0.8" />
         <PackageReference Include="Microsoft.Extensions.Hosting" Version="3.0.0" />
+        <PackageReference Include="MQTTnet.Extensions.ManagedClient" Version="3.0.8" />
+        <PackageReference Include="Portable.BouncyCastle" Version="1.8.5.2" />
         <PackageReference Include="System.Device.Gpio" Version="1.0.0" />
     </ItemGroup>
 
@@ -79,4 +82,8 @@
     <ItemGroup>
       <ProjectReference Include="..\NucuCar.Domain\NucuCar.Domain.csproj" />
     </ItemGroup>
+
+    <ItemGroup>
+      <Folder Include="Certificates" />
+    </ItemGroup>
 </Project>

NucuCar.Sensors/Telemetry/BackgroundWorker.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Configuration;
@@ -9,6 +8,11 @@ namespace NucuCar.Sensors.Telemetry
 {
     public class BackgroundWorker : BackgroundService
     {
+        private readonly string _projectId;
+        private readonly string _region;
+        private readonly string _registryId;
+        private readonly string _deviceId;
+        private readonly string _rs256KeyFile;
         private readonly bool _serviceEnabled;
         private readonly int _interval;
         private readonly ILogger _logger;
@@ -19,6 +23,11 @@ namespace NucuCar.Sensors.Telemetry
             var configSection = configuration.GetSection("Telemetry");
             _serviceEnabled = configSection.GetValue<bool>("Enabled");
             _interval = configSection.GetValue<int>("Interval");
+            _projectId = configSection.GetValue<string>("ProjectId");
+            _region = configSection.GetValue<string>("Region");
+            _registryId = configSection.GetValue<string>("RegistryId");
+            _deviceId = configSection.GetValue<string>("DeviceId");
+            _rs256KeyFile = configSection.GetValue<string>("RS256File");
         }
 
         protected override async Task ExecuteAsync(CancellationToken stoppingToken)
@@ -27,13 +36,23 @@ namespace NucuCar.Sensors.Telemetry
             {
                 return;
             }
+
             await Task.Delay(_interval, stoppingToken);
 
             using var telemetryService = TelemetryService.Instance;
+
+            telemetryService.SetLogger(_logger);
+            telemetryService.ProjectId = _projectId;
+            telemetryService.DeviceId = _deviceId;
+            telemetryService.RegistryId = _registryId;
+            telemetryService.Region = _region;
+            telemetryService.Rs256File = _rs256KeyFile;
+
+            await telemetryService.StartAsync();
             while (!stoppingToken.IsCancellationRequested)
             {
                 _logger.LogInformation("Publishing telemetry data!");
-                await telemetryService.PublishData();
+                await telemetryService.PublishDataAsync(stoppingToken);
                 await Task.Delay(_interval, stoppingToken);
             }
         }

NucuCar.Sensors/Telemetry/TelemetryService.cs

@@ -1,43 +1,112 @@
 using System;
 using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Security.Cryptography;
+using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using MQTTnet;
+using MQTTnet.Client.Options;
+using MQTTnet.Extensions.ManagedClient;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.OpenSsl;
+using Org.BouncyCastle.Security;
 
 namespace NucuCar.Sensors.Telemetry
 {
     public class TelemetryService : IDisposable
     {
         private readonly List<ITelemetrySensor> _registeredSensors;
+        private readonly IManagedMqttClient _mqttClient;
+        private ILogger _logger;
 
         /* Singleton Instance */
         public static TelemetryService Instance { get; } = new TelemetryService();
+        public string ProjectId { get; set; }
+        public string Region { get; set; }
+        public string RegistryId { get; set; }
+        public string DeviceId { get; set; }
+        public string Rs256File { get; set; }
 
         static TelemetryService()
         {
         }
 
+        private string GetMqttPassword()
+        {
+            string jwt;
+            AsymmetricCipherKeyPair keyPair;
+
+            using (var sr = new StreamReader(Rs256File))
+            {
+                var pr = new PemReader(sr);
+                keyPair = (AsymmetricCipherKeyPair) pr.ReadObject();
+            }
+            
+            var rsaParams = DotNetUtilities.ToRSAParameters((RsaPrivateCrtKeyParameters)keyPair.Private);
+
+            using (var rsa = new RSACryptoServiceProvider())
+            {
+                rsa.ImportParameters(rsaParams);
+                jwt = Jose.JWT.Encode(new Dictionary<string, object>()
+                {
+                    ["iat"] = DateTime.UtcNow,
+                    ["exp"] = DateTime.UtcNow.AddMinutes(60),
+                    ["aud"] = ProjectId
+                }, rsa, Jose.JwsAlgorithm.RS256);
+            }
+
+            return jwt;
+        }
+
         private TelemetryService()
         {
             _registeredSensors = new List<ITelemetrySensor>(5);
+
+            _mqttClient = new MqttFactory().CreateManagedMqttClient();
         }
 
         public void Dispose()
         {
         }
 
-        public async Task PublishData()
+        public async Task StartAsync()
+        {
+            var options = new ManagedMqttClientOptionsBuilder()
+                .WithAutoReconnectDelay(TimeSpan.FromSeconds(5))
+                .WithClientOptions(new MqttClientOptionsBuilder()
+                    .WithClientId($"projects/{ProjectId}/locations/{Region}/registries/{RegistryId}/devices/{DeviceId}")
+                    .WithCredentials("unused", GetMqttPassword())
+                    .WithTcpServer("mqtt.googleapis.com")
+                    .WithTls().Build())
+                .Build();
+            
+            _logger.LogInformation("Starting the MQTT client.");
+            await _mqttClient.StartAsync(options);
+        }
+
+        public async Task PublishDataAsync(CancellationToken cancellationToken)
         {
             foreach (var sensor in _registeredSensors)
             {
                 var data = sensor.GetTelemetryData();
-                await UploadData(data);
+                await UploadData(data, cancellationToken);
             }
         }
 
-        private async Task UploadData(Dictionary<string, double> data)
+        private async Task UploadData(Dictionary<string, double> data, CancellationToken cancellationToken)
         {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                _logger.LogInformation("Stopping the MQTT client, cancellation requested.");
+                await _mqttClient.StopAsync();
+            }
+
             foreach (var entry in data)
             {
-                // TODO: Publish data to IoTCore
+                await _mqttClient.PublishAsync(entry.Key, entry.Value.ToString(CultureInfo.InvariantCulture));
             }
         }
 
@@ -50,5 +119,10 @@ namespace NucuCar.Sensors.Telemetry
         {
             _registeredSensors.Remove(sensor);
         }
+
+        public void SetLogger(ILogger logger)
+        {
+            _logger = logger;
+        }
     }
 }

NucuCar.Sensors/appsettings.json

@@ -1,7 +1,12 @@
 {
   "Telemetry": {
     "Enabled": true,
-    "Interval": 5000
+    "Interval": 5000,
+    "ProjectId": "playground-239221",
+    "DeviceId": "3087236321317137",
+    "RegistryId": "Development",
+    "Region": "europe-west1",
+    "RS256File": "Certificates\\key.key"
   },
   "EnvironmentSensor": {
     "Enabled": true,