PortAllocator.cs

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
 
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
 
using Tgstation.Server.Host.Configuration;
using Tgstation.Server.Host.Core;
using Tgstation.Server.Host.Database;
using Tgstation.Server.Host.Extensions;
 
namespace Tgstation.Server.Host.Utils
{
    sealed class PortAllocator : IPortAllocator
    {
        readonly IServerPortProvider serverPortProvider;
 
        readonly IDatabaseContext databaseContext;
 
        readonly ILogger<PortAllocator> logger;
 
        readonly SwarmConfiguration swarmConfiguration;
 
        public PortAllocator(
            IServerPortProvider serverPortProvider,
            IDatabaseContext databaseContext,
            IOptions<SwarmConfiguration> swarmConfigurationOptions,
            ILogger<PortAllocator> logger)
        {
            this.serverPortProvider = serverPortProvider ?? throw new ArgumentNullException(nameof(serverPortProvider));
            this.databaseContext = databaseContext ?? throw new ArgumentNullException(nameof(databaseContext));
            swarmConfiguration = swarmConfigurationOptions?.Value ?? throw new ArgumentNullException(nameof(swarmConfigurationOptions));
            this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
        }
 
        public async Task<ushort?> GetAvailablePort(ushort basePort, bool checkOne, CancellationToken cancellationToken)
        {
            logger.LogTrace("Port allocation >= {basePort} requested...", basePort);
 
            var ddPorts = await databaseContext
                .DreamDaemonSettings
                .AsQueryable()
                .Where(x => x.Instance.SwarmIdentifer == swarmConfiguration.Identifier)
                .Select(x => x.Port)
                .ToListAsync(cancellationToken);
 
            var dmPorts = await databaseContext
                .DreamMakerSettings
                .AsQueryable()
                .Where(x => x.Instance.SwarmIdentifer == swarmConfiguration.Identifier)
                .Select(x => x.ApiValidationPort)
                .ToListAsync(cancellationToken);
 
            var exceptions = new List<Exception>();
            ushort port = 0;
            try
            {
                for (port = basePort; port < ushort.MaxValue; ++port)
                {
                    if (checkOne && port != basePort)
                        break;
 
                    if (port == serverPortProvider.HttpApiPort
                        || ddPorts.Contains(port)
                        || dmPorts.Contains(port))
                        continue;
 
                    try
                    {
                        SocketExtensions.BindTest(port, false);
                    }
                    catch (Exception ex)
                    {
                        exceptions.Add(ex);
                        continue;
                    }
 
                    logger.LogInformation("Allocated port {port}", port);
                    return port;
                }
 
                logger.LogWarning("Unable to allocate port >= {basePort}!", basePort);
                return null;
            }
            finally
            {
                if (port != basePort)
                {
                    logger.LogDebug(
                        exceptions.Count == 1
                            ? exceptions.First()
                            : new AggregateException(exceptions),
                        "Failed to allocate ports {basePort}-{lastCheckedPort}!",
                        basePort,
                        port - 1);
                }
            }
        }
    }
}