MalwareMultiScan/MalwareMultiScan.Api/Services/Implementations/ReceiverHostedService.cs

using System;
using System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using EasyNetQ;
using MalwareMultiScan.Api.Services.Interfaces;
using MalwareMultiScan.Backends.Messages;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;

namespace MalwareMultiScan.Api.Services.Implementations
{
    /// <inheritdoc />
    public class ReceiverHostedService : IReceiverHostedService
    {
        private readonly IBus _bus;
        private readonly IConfiguration _configuration;
        private readonly IHttpClientFactory _httpClientFactory;
        private readonly ILogger<ReceiverHostedService> _logger;
        private readonly IScanResultService _scanResultService;

        /// <summary>
        /// Initialize receiver hosted service.
        /// </summary>
        /// <param name="bus">EasyNetQ bus.</param>
        /// <param name="configuration">Configuration.</param>
        /// <param name="scanResultService">Scan result service.</param>
        /// <param name="logger">Logger.</param>
        /// <param name="httpClientFactory">HTTP client factory.</param>
        public ReceiverHostedService(IBus bus, IConfiguration configuration, IScanResultService scanResultService,
            ILogger<ReceiverHostedService> logger, IHttpClientFactory httpClientFactory)
        {
            _bus = bus;
            _configuration = configuration;
            _scanResultService = scanResultService;
            _logger = logger;
            _httpClientFactory = httpClientFactory;
        }


        /// <inheritdoc />
        public Task StartAsync(CancellationToken cancellationToken)
        {
            _bus.Receive<ScanResultMessage>(
                _configuration.GetValue<string>("ResultsSubscriptionId"), StoreScanResult);

            _logger.LogInformation(
                "Started hosted service for receiving scan results");

            return Task.CompletedTask;
        }

        /// <inheritdoc />
        public Task StopAsync(CancellationToken cancellationToken)
        {
            _bus?.Dispose();

            _logger.LogInformation(
                "Stopped hosted service for receiving scan results");

            return Task.CompletedTask;
        }

        private async Task StoreScanResult(ScanResultMessage message)
        {
            message.Threats ??= new string[] { };

            _logger.LogInformation(
                $"Received a result from {message.Backend} for {message.Id} " +
                $"with threats {string.Join(",", message.Threats)}");

            await _scanResultService.UpdateScanResultForBackend(
                message.Id, message.Backend, message.Duration, true,
                message.Succeeded, message.Threats);

            var result = await _scanResultService.GetScanResult(message.Id);

            if (result?.CallbackUrl == null)
                return;

            var cancellationTokenSource = new CancellationTokenSource(
                TimeSpan.FromSeconds(3));

            using var httpClient = _httpClientFactory.CreateClient();

            try
            {
                var response = await httpClient.PostAsync(
                    result.CallbackUrl,
                    new StringContent(JsonConvert.SerializeObject(result), Encoding.UTF8, "application/json"),
                    cancellationTokenSource.Token);

                response.EnsureSuccessStatusCode();
            }
            catch (Exception exception)
            {
                _logger.LogError(exception, $"Failed to POST to callback URL {result.CallbackUrl}");
            }
        }
    }
}