cdn downloads support

LightlessSyncServer/LightlessSyncShared/Utils/Configuration/StaticFilesServerConfiguration.cs

@@ -20,6 +20,8 @@ public class StaticFilesServerConfiguration : LightlessConfigurationBase
     public string ColdStorageDirectory { get; set; } = null;
     public double ColdStorageSizeHardLimitInGiB { get; set; } = -1;
     public int ColdStorageUnusedFileRetentionPeriodInDays { get; set; } = 30;
+    public bool EnableDirectDownloads { get; set; } = true;
+    public int DirectDownloadTokenLifetimeSeconds { get; set; } = 300;
     [RemoteConfiguration]
     public double SpeedTestHoursRateLimit { get; set; } = 0.5;
     [RemoteConfiguration]
@@ -40,6 +42,8 @@ public class StaticFilesServerConfiguration : LightlessConfigurationBase
         sb.AppendLine($"{nameof(CacheDirectory)} => {CacheDirectory}");
         sb.AppendLine($"{nameof(DownloadQueueSize)} => {DownloadQueueSize}");
         sb.AppendLine($"{nameof(DownloadQueueReleaseSeconds)} => {DownloadQueueReleaseSeconds}");
+        sb.AppendLine($"{nameof(EnableDirectDownloads)} => {EnableDirectDownloads}");
+        sb.AppendLine($"{nameof(DirectDownloadTokenLifetimeSeconds)} => {DirectDownloadTokenLifetimeSeconds}");
         return sb.ToString();
     }
 }

LightlessSyncServer/LightlessSyncStaticFilesServer/Controllers/ServerFilesController.cs

@@ -10,6 +10,7 @@ using LightlessSyncShared.Services;
 using LightlessSyncShared.Utils.Configuration;
 using LightlessSyncStaticFilesServer.Services;
 using LightlessSyncStaticFilesServer.Utils;
+using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.SignalR;
 using Microsoft.EntityFrameworkCore;
@@ -32,12 +33,13 @@ public class ServerFilesController : ControllerBase
     private readonly IDbContextFactory<LightlessDbContext> _lightlessDbContext;
     private readonly LightlessMetrics _metricsClient;
     private readonly MainServerShardRegistrationService _shardRegistrationService;
+    private readonly CDNDownloadUrlService _cdnDownloadUrlService;
 
     public ServerFilesController(ILogger<ServerFilesController> logger, CachedFileProvider cachedFileProvider,
         IConfigurationService<StaticFilesServerConfiguration> configuration,
         IHubContext<LightlessHub> hubContext,
         IDbContextFactory<LightlessDbContext> lightlessDbContext, LightlessMetrics metricsClient,
-        MainServerShardRegistrationService shardRegistrationService) : base(logger)
+        MainServerShardRegistrationService shardRegistrationService, CDNDownloadUrlService cdnDownloadUrlService) : base(logger)
     {
         _basePath = configuration.GetValueOrDefault(nameof(StaticFilesServerConfiguration.UseColdStorage), false)
             ? configuration.GetValue<string>(nameof(StaticFilesServerConfiguration.ColdStorageDirectory))
@@ -48,6 +50,7 @@ public class ServerFilesController : ControllerBase
         _lightlessDbContext = lightlessDbContext;
         _metricsClient = metricsClient;
         _shardRegistrationService = shardRegistrationService;
+        _cdnDownloadUrlService = cdnDownloadUrlService;
     }
 
     [HttpPost(LightlessFiles.ServerFiles_DeleteAll)]
@@ -105,6 +108,16 @@ public class ServerFilesController : ControllerBase
                 baseUrl = shard.Value ?? _configuration.GetValue<Uri>(nameof(StaticFilesServerConfiguration.CdnFullUrl));
             }
 
+            var cdnDownloadUrl = string.Empty;
+            if (forbiddenFile == null)
+            {
+                var directUri = _cdnDownloadUrlService.TryCreateDirectDownloadUri(baseUrl, file.Hash);
+                if (directUri != null)
+                {
+                    cdnDownloadUrl = directUri.ToString();
+                }
+            }
+
             response.Add(new DownloadFileDto
             {
                 FileExists = file.Size > 0,
@@ -113,6 +126,7 @@ public class ServerFilesController : ControllerBase
                 Hash = file.Hash,
                 Size = file.Size,
                 Url = baseUrl?.ToString() ?? string.Empty,
+                CDNDownloadUrl = cdnDownloadUrl,
                 RawSize = file.RawSize
             });
         }
@@ -127,6 +141,30 @@ public class ServerFilesController : ControllerBase
         return Ok(JsonSerializer.Serialize(allFileShards.SelectMany(t => t.RegionUris.Select(v => v.Value.ToString()))));
     }
 
+    [HttpGet(LightlessFiles.ServerFiles_DirectDownload + "/{hash}")]
+    [AllowAnonymous]
+    public async Task<IActionResult> DownloadFileDirect(string hash, [FromQuery] long expires, [FromQuery] string signature)
+    {
+        if (!_cdnDownloadUrlService.DirectDownloadsEnabled)
+        {
+            return NotFound();
+        }
+
+        hash = hash.ToUpperInvariant();
+        if (!_cdnDownloadUrlService.TryValidateSignature(hash, expires, signature))
+        {
+            return Unauthorized();
+        }
+
+        var fileInfo = await _cachedFileProvider.DownloadAndGetLocalFileInfo(hash).ConfigureAwait(false);
+        if (fileInfo == null)
+        {
+            return NotFound();
+        }
+
+        return PhysicalFile(fileInfo.FullName, "application/octet-stream");
+    }
+
     [HttpPost(LightlessFiles.ServerFiles_FilesSend)]
     public async Task<IActionResult> FilesSend([FromBody] FilesSendDto filesSendDto)
     {
@@ -360,4 +398,4 @@ public class ServerFilesController : ControllerBase
             buffer[i] ^= 42;
         }
     }
-}
+}

LightlessSyncServer/LightlessSyncStaticFilesServer/Services/CDNDownloadUrlService.cs

@@ -0,0 +1,108 @@
+using LightlessSync.API.Routes;
+using LightlessSyncShared.Services;
+using LightlessSyncShared.Utils.Configuration;
+using Microsoft.AspNetCore.Http.Extensions;
+using Microsoft.AspNetCore.WebUtilities;
+using System.Security.Cryptography;
+using System.Text;
+using System.Globalization;
+using System.Linq;
+
+namespace LightlessSyncStaticFilesServer.Services;
+
+public class CDNDownloadUrlService
+{
+    private readonly IConfigurationService<StaticFilesServerConfiguration> _staticConfig;
+    private readonly IConfigurationService<LightlessConfigurationBase> _globalConfig;
+    private readonly ILogger<CDNDownloadUrlService> _logger;
+
+    public CDNDownloadUrlService(IConfigurationService<StaticFilesServerConfiguration> staticConfig,
+        IConfigurationService<LightlessConfigurationBase> globalConfig, ILogger<CDNDownloadUrlService> logger)
+    {
+        _staticConfig = staticConfig;
+        _globalConfig = globalConfig;
+        _logger = logger;
+    }
+
+    public bool DirectDownloadsEnabled =>
+        _staticConfig.GetValueOrDefault(nameof(StaticFilesServerConfiguration.EnableDirectDownloads), false);
+
+    public Uri? TryCreateDirectDownloadUri(Uri? baseUri, string hash)
+    {
+        if (!DirectDownloadsEnabled || baseUri == null)
+        {
+            return null;
+        }
+
+        if (!IsSupportedHash(hash))
+        {
+            _logger.LogDebug("Skipping direct download link generation for invalid hash {hash}", hash);
+            return null;
+        }
+
+        var normalizedHash = hash.ToUpperInvariant();
+
+        var lifetimeSeconds = Math.Max(5,
+            _staticConfig.GetValueOrDefault(nameof(StaticFilesServerConfiguration.DirectDownloadTokenLifetimeSeconds), 300));
+        var expiresAt = DateTimeOffset.UtcNow.AddSeconds(lifetimeSeconds);
+        var signature = CreateSignature(normalizedHash, expiresAt.ToUnixTimeSeconds());
+
+        var directPath = $"{LightlessFiles.ServerFiles}/{LightlessFiles.ServerFiles_DirectDownload}/{normalizedHash}";
+        var builder = new UriBuilder(new Uri(baseUri, directPath));
+        var query = new QueryBuilder
+        {
+            { "expires", expiresAt.ToUnixTimeSeconds().ToString(CultureInfo.InvariantCulture) },
+            { "signature", signature }
+        };
+        builder.Query = query.ToQueryString().Value!.TrimStart('?');
+        return builder.Uri;
+    }
+
+    public bool TryValidateSignature(string hash, long expiresUnixSeconds, string signature)
+    {
+        if (!DirectDownloadsEnabled)
+        {
+            return false;
+        }
+
+        if (string.IsNullOrEmpty(signature) || !IsSupportedHash(hash))
+        {
+            return false;
+        }
+
+        var normalizedHash = hash.ToUpperInvariant();
+
+        DateTimeOffset expiresAt;
+        try
+        {
+            expiresAt = DateTimeOffset.FromUnixTimeSeconds(expiresUnixSeconds);
+        }
+        catch (ArgumentOutOfRangeException)
+        {
+            return false;
+        }
+
+        if (expiresAt < DateTimeOffset.UtcNow)
+        {
+            return false;
+        }
+
+        var expected = CreateSignature(normalizedHash, expiresAt.ToUnixTimeSeconds());
+        return CryptographicOperations.FixedTimeEquals(
+            Encoding.UTF8.GetBytes(expected),
+            Encoding.UTF8.GetBytes(signature));
+    }
+
+    private string CreateSignature(string hash, long expiresUnixSeconds)
+    {
+        var signingKey = _globalConfig.GetValue<string>(nameof(LightlessConfigurationBase.Jwt));
+        using var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(signingKey));
+        var payload = Encoding.UTF8.GetBytes($"{hash}:{expiresUnixSeconds}");
+        return WebEncoders.Base64UrlEncode(hmac.ComputeHash(payload));
+    }
+
+    private static bool IsSupportedHash(string hash)
+    {
+        return hash.Length == 40 && hash.All(char.IsAsciiLetterOrDigit);
+    }
+}

LightlessSyncServer/LightlessSyncStaticFilesServer/Startup.cs

@@ -87,6 +87,7 @@ public class Startup
         services.AddSingleton<RequestFileStreamResultFactory>();
         services.AddSingleton<ServerTokenGenerator>();
         services.AddSingleton<RequestQueueService>();
+        services.AddSingleton<CDNDownloadUrlService>();
         services.AddHostedService(p => p.GetService<RequestQueueService>());
         services.AddHostedService(m => m.GetService<FileStatisticsService>());
         services.AddSingleton<IConfigurationService<LightlessConfigurationBase>, LightlessConfigurationServiceClient<LightlessConfigurationBase>>();

LightlessSyncServer/LightlessSyncStaticFilesServer/appsettings.json

@@ -25,7 +25,9 @@
     "UnusedFileRetentionPeriodInDays": 7,
     "CacheDirectory": "G:\\ServerTest",
     "ServiceAddress": "http://localhost:5002",
-    "RemoteCacheSourceUri": ""
+    "RemoteCacheSourceUri": "",
+    "EnableDirectDownloads": true,
+    "DirectDownloadTokenLifetimeSeconds": 300
   },
   "AllowedHosts": "*"
 }