Add MusicBridge protocol documentation and implement system volume control

- Created PROTOCOL.md to outline the MusicBridge protocol v1, detailing setup, TLS, pairing, state management, and command structure. - Implemented SystemVolume class for managing system audio levels, including methods for setting, reading, changing, and muting volume. - Added unit tests for the MusicBridge agent, covering pairing, identity storage, command validation, and media state management. - Included tests for real-time media reading from Windows and ensured proper handling of artwork caching and retrieval.
2026-09-09 01:05:52 +03:00
parent 5e476c4c2f
commit d5e827112a
23 changed files with 2067 additions and 72 deletions
@@ -0,0 +1,90 @@
+using System.Security.Cryptography;
+using System.Security.Cryptography.X509Certificates;
+using System.Text.Json;
+
+namespace MusicBridge.Agent.Network;
+
+internal sealed record TrustedDevice(string Id, string Name, string TokenHash, DateTimeOffset CreatedAt);
+
+internal sealed class IdentityStore : IDisposable
+{
+    private sealed record Identity(int Version, byte[] Certificate, TrustedDevice[] Devices);
+    private readonly FileStream owner;
+    private readonly string path;
+    private Identity identity = null!;
+    public X509Certificate2 Certificate { get; private set; } = null!;
+    public IReadOnlyList<TrustedDevice> Devices => identity.Devices;
+    public static string DefaultDirectory => Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "MusicBridge");
+
+    public IdentityStore(string directory)
+    {
+        Directory.CreateDirectory(directory);
+        path = Path.Combine(directory, "identity.dat");
+        // Prevent two agents from racing the certificate or overwriting trusted devices.
+        owner = new FileStream(Path.Combine(directory, "identity.lock"), FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
+        try
+        {
+            if (File.Exists(path))
+            {
+                if (new FileInfo(path).Length > 1024 * 1024) throw new InvalidDataException("Хранилище слишком большое.");
+                var clear = UserProtection.Unprotect(File.ReadAllBytes(path));
+                try { identity = JsonSerializer.Deserialize<Identity>(clear) ?? throw new InvalidDataException("Пустое хранилище."); }
+                finally { CryptographicOperations.ZeroMemory(clear); }
+                if (identity.Version != 1 || identity.Certificate is null || identity.Devices is null || identity.Devices.Length > 8
+                    || identity.Devices.Any(d => d is null || !Guid.TryParseExact(d.Id, "N", out _) || string.IsNullOrWhiteSpace(d.Name)
+                        || d.Name.Length > 64 || d.TokenHash is null || d.TokenHash.Length != 64 || !d.TokenHash.All(Uri.IsHexDigit))
+                    || identity.Devices.Select(d => d.Id).Distinct().Count() != identity.Devices.Length)
+                    throw new InvalidDataException("Неверный формат хранилища.");
+                Certificate = X509CertificateLoader.LoadPkcs12(identity.Certificate, null);
+                if (!Certificate.HasPrivateKey || Certificate.NotAfter.ToUniversalTime() <= DateTime.UtcNow)
+                    throw new InvalidDataException("Сертификат недоступен или истёк. Хранилище сохранено без изменений.");
+            }
+            else
+            {
+                Certificate = AgentCertificate.Create();
+                identity = new(1, Certificate.Export(X509ContentType.Pfx), []);
+                Save(identity);
+            }
+        }
+        catch
+        {
+            Certificate?.Dispose();
+            if (identity?.Certificate is { } bytes) CryptographicOperations.ZeroMemory(bytes);
+            owner.Dispose();
+            throw;
+        }
+    }
+
+    public void SaveDevices(TrustedDevice[] devices)
+    {
+        var updated = identity with { Devices = devices };
+        Save(updated); // Commit to memory only after the protected file is safely replaced.
+        identity = updated;
+    }
+
+    private void Save(Identity value)
+    {
+        var clear = JsonSerializer.SerializeToUtf8Bytes(value);
+        byte[] encrypted;
+        try { encrypted = UserProtection.Protect(clear); }
+        finally { CryptographicOperations.ZeroMemory(clear); }
+        var temporary = path + ".tmp";
+        try
+        {
+            using (var file = new FileStream(temporary, FileMode.Create, FileAccess.Write, FileShare.None))
+            {
+                file.Write(encrypted);
+                file.Flush(flushToDisk: true);
+            }
+            File.Move(temporary, path, overwrite: true);
+        }
+        finally { if (File.Exists(temporary)) File.Delete(temporary); }
+    }
+
+    public void Dispose()
+    {
+        Certificate.Dispose();
+        CryptographicOperations.ZeroMemory(identity.Certificate);
+        owner.Dispose();
+    }
+}