feat(browser): stream bounded live session updates (#26)

2026-07-16 23:25:48 +02:00
parent 95c3a4aed6
commit 06c4ecf8f3
34 changed files with 2249 additions and 27 deletions
@@ -0,0 +1,108 @@
+using System.Security.Cryptography;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using FinalFactory.Rendezvous.Contracts;
+using FinalFactory.Rendezvous.Server.State;
+
+namespace FinalFactory.Rendezvous.Server.Browser;
+
+internal sealed class SessionStreamCursorCodec : IDisposable
+{
+    private const string Prefix = "rvs1";
+    private readonly EphemeralCursorProtector _protector = new();
+
+    public string Encode(VisibleListingQuery query, long revision, DateTimeOffset now)
+    {
+        ArgumentOutOfRangeException.ThrowIfNegative(revision);
+        SessionStreamCursorPayload payload = new()
+        {
+            GameId = query.Scope.GameId.Value,
+            EnvironmentId = query.Scope.EnvironmentId.Value,
+            ProtocolVersion = query.ProtocolVersion,
+            RegionId = query.RegionId?.Value,
+            ExcludeFull = query.ExcludeFull,
+            Revision = revision,
+            ExpiresAtUnixSeconds = now.AddMinutes(10).ToUnixTimeSeconds(),
+        };
+        byte[] encoded = JsonSerializer.SerializeToUtf8Bytes(payload, ContractJson.Options);
+        try
+        {
+            return _protector.Protect(Prefix, encoded);
+        }
+        finally
+        {
+            CryptographicOperations.ZeroMemory(encoded);
+        }
+    }
+
+    public bool TryDecode(
+        string? cursor,
+        VisibleListingQuery query,
+        DateTimeOffset now,
+        out long revision)
+    {
+        revision = 0;
+        if (cursor is null || !_protector.TryUnprotect(Prefix, cursor, out byte[] encodedPayload))
+        {
+            return false;
+        }
+
+        SessionStreamCursorPayload? payload;
+        try
+        {
+            payload = JsonSerializer.Deserialize<SessionStreamCursorPayload>(
+                encodedPayload,
+                ContractJson.Options);
+        }
+        catch (JsonException)
+        {
+            payload = null;
+        }
+        finally
+        {
+            CryptographicOperations.ZeroMemory(encodedPayload);
+        }
+
+        if (payload is null
+            || payload.Revision < 0
+            || payload.ExpiresAtUnixSeconds <= now.ToUnixTimeSeconds()
+            || !string.Equals(payload.GameId, query.Scope.GameId.Value, StringComparison.Ordinal)
+            || !string.Equals(payload.EnvironmentId, query.Scope.EnvironmentId.Value, StringComparison.Ordinal)
+            || payload.ProtocolVersion != query.ProtocolVersion
+            || !string.Equals(payload.RegionId, query.RegionId?.Value, StringComparison.Ordinal)
+            || payload.ExcludeFull != query.ExcludeFull)
+        {
+            return false;
+        }
+
+        revision = payload.Revision;
+        return true;
+    }
+
+    public void Dispose() => _protector.Dispose();
+
+    public override string ToString() => "[SessionStreamCursorCodec: key and cursors redacted]";
+}
+
+internal sealed class SessionStreamCursorPayload
+{
+    [JsonRequired]
+    public string GameId { get; set; } = string.Empty;
+
+    [JsonRequired]
+    public string EnvironmentId { get; set; } = string.Empty;
+
+    [JsonRequired]
+    public uint ProtocolVersion { get; set; }
+
+    public string? RegionId { get; set; }
+
+    [JsonRequired]
+    public bool ExcludeFull { get; set; }
+
+    [JsonRequired]
+    public long Revision { get; set; }
+
+    [JsonRequired]
+    public long ExpiresAtUnixSeconds { get; set; }
+}