cdn downloads support

2025-10-10 07:37:33 +09:00
parent 479b80a5a0
commit b6907a2704
6 changed files with 157 additions and 4 deletions
--- a/LightlessSyncServer/LightlessSyncStaticFilesServer/Services/CDNDownloadUrlService.cs
+++ b/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);
+    }
+}