Deserialize gamecode as packed in PackedGameDataTo (#738)

* Deserialize gamecode as packed in PackedGameDataTo

Most packets use a normal 32 bit int but not PackedGameDataTo. Instead,
Innersloth decided to waste a byte by using WritePacked. As v2 game
codes are always negative, this is less efficient, but alas.

It was documented in the pseudocode and I didn't spot the difference
when reviewing the implementation, so I made this mistake when
deduplicating this code.

Test plan:
- Start EHR on at least 2 clients
- Use the game mode "Natural Disasters"
- Observe that pixelated blobs are visible for all players, not just the host

* uopt: stop parsing code to string

* Address review comments

diff --git a/src/Impostor.Server/Net/Client.cs b/src/Impostor.Server/Net/Client.cs
index 65d8e4960f0dfb434b4caa3f9ab6c4e43b1c70cc..97bb7c27577fd38fedb36a18ff478ec3ac138d87 100644 (file)
--- a/src/Impostor.Server/Net/Client.cs
+++ b/src/Impostor.Server/Net/Client.cs
@@ -268,10 +268,30 @@ namespace Impostor.Server.Net
 
                 case MessageFlags.PackedGameDataTo:
                 {
+                    if (Player == null)
+                    {
+                        return;
+                    }
+
+                    var game = Player.Game;
+
+                    // Innersloth Special: this message uses PackedInt32 instead of a normal int32
+                    var code = reader.ReadPackedInt32();
+
+                    if (code != game.Code.Value)
+                    {
+                        _logger.LogWarning("gcm2 {0} {1}", code, game.Code.Value);
+                        return;
+                    }
+
                     // We're limiting this to hosts right now. If you have a use case for this for
                     // players to use this feature, we're open to changing this.
-                    if (!IsPacketAllowed(reader, true, flag))
+                    if (game.HostId != Id)
                     {
+                        await ReportCheatAsync(
+                            new CheatContext(MessageFlags.FlagToString(flag)),
+                            CheatCategory.MustBeHost,
+                            "Client sent a PackedGameDataTo message");
                         return;
                     }
 
@@ -293,7 +313,7 @@ namespace Impostor.Server.Net
                             return;
                         }
 
-                        if (packed.ReadInt32() != Player!.Game.Code)
+                        if (packed.ReadInt32() != game.Code.Value)
                         {
                             _logger.LogWarning("PackedGameDataTo contained GameDataTo for the wrong game.");
                             return;
@@ -446,7 +466,8 @@ namespace Impostor.Server.Net
             var game = Player.Game;
 
             // GameCode must match code of the current game assigned to the player.
-            if (message.ReadInt32() != game.Code)
+            var code = message.ReadInt32();
+            if (code != game.Code.Value)
             {
                 return false;
             }