browse_rsc() hashing (#2373)

Author: amylizzle

OpenDreamClient/OpenDreamClient.csproj

@@ -17,6 +17,7 @@
     <ProjectReference Include="..\RobustToolbox\Robust.Shared.Maths\Robust.Shared.Maths.csproj" />
     <ProjectReference Include="..\RobustToolbox\Robust.Shared\Robust.Shared.csproj" />
     <ProjectReference Include="..\RobustToolbox\Robust.Client\Robust.Client.csproj" />
+    <PackageReference Include="SpaceWizards.Sodium" />
   </ItemGroup>
   <Import Project="..\RobustToolbox\MSBuild\Robust.Properties.targets" />
   <Import Project="..\RobustToolbox\MSBuild\XamlIL.targets" />

OpenDreamClient/Resources/DreamResourceManager.cs

@@ -5,6 +5,8 @@
 using Robust.Shared.ContentPack;
 using Robust.Shared.Network;
 using Robust.Shared.Utility;
+using System.Linq;
+using SpaceWizards.Sodium;
 
 namespace OpenDreamClient.Resources;
 
@@ -69,21 +71,32 @@ private void EnsureCacheDirectory() {
     }
 
     private void RxBrowseResource(MsgBrowseResource message) {
-        _sawmill.Debug($"Received cache check for {message.Filename}");
+        _sawmill.Debug($"Received cache check for {message.Filename} hash: {BitConverter.ToString(message.DataHash)}");
         EnsureCacheDirectory();
-        if(_resourceManager.UserData.Exists(GetCacheFilePath(message.Filename))){ //TODO CHECK HASH
+        if(_resourceManager.UserData.Exists(GetCacheFilePath(message.Filename)) && GetFileHash(GetCacheFilePath(message.Filename)).SequenceEqual(message.DataHash)){
             _sawmill.Debug($"Cache hit for {message.Filename}");
         } else {
             if(_activeBrowseRscRequests.Contains(message.Filename)) //we've already requested it, don't need to do it again
                 return;
-            _sawmill.Debug($"Cache miss for {message.Filename}, requesting from server.");
+            if (_resourceManager.UserData.Exists(GetCacheFilePath(message.Filename))) {
+                _sawmill.Debug($"Cache hit for {message.Filename} but hashes did not match (hash: {BitConverter.ToString(GetFileHash(GetCacheFilePath(message.Filename)))}). Re-requesting!");
+                _resourceManager.UserData.Delete(GetCacheFilePath(message.Filename));
+            } else
+                _sawmill.Debug($"Cache miss for {message.Filename}, requesting from server.");
             _activeBrowseRscRequests.Add(message.Filename);
             _netManager.ServerChannel?.SendMessage(new MsgBrowseResourceRequest(){ Filename = message.Filename});
         }
     }
 
+    private byte[] GetFileHash(ResPath path) {
+        var stream = _resourceManager.UserData.OpenRead(path);
+        Span<byte> filebytes = new(new byte[stream.Length]);
+        stream.ReadToEnd(filebytes);
+        return CryptoGenericHashBlake2B.Hash(32, filebytes, ReadOnlySpan<byte>.Empty);
+    }
+
     private void RxBrowseResourceResponse(MsgBrowseResourceResponse message) {
-        if(_activeBrowseRscRequests.Contains(message.Filename)) {
+        if (_activeBrowseRscRequests.Contains(message.Filename)) {
             _activeBrowseRscRequests.Remove(message.Filename);
             EnsureCacheDirectory();
             CreateCacheFile(message.Filename, message.Data);
@@ -227,7 +240,7 @@ public bool EnsureCacheFile(string filename, int timeoutSeconds = 5) {
 
                 return _resourceManager.UserData.Exists(actualPath);
             } else {
-                _sawmill.Error("Cache was ensured for a file that does not exist in cache and is not requested. Probably somebody called browse() without browse_rsc() first.");
+                _sawmill.Error($"Cache was ensured for a file ({filename}) that does not exist in cache and is not requested. Probably somebody called browse() without browse_rsc() first.");
                 return false;
             }
         }

OpenDreamRuntime/DreamConnection.cs

@@ -9,6 +9,7 @@
 using OpenDreamShared.Network.Messages;
 using Robust.Shared.Enums;
 using Robust.Shared.Player;
+using SpaceWizards.Sodium;
 
 namespace OpenDreamRuntime;
 
@@ -373,7 +374,7 @@ public void BrowseResource(DreamResource resource, string filename) {
 
         var msg = new MsgBrowseResource() {
             Filename = filename,
-            DataHash = resource.ResourceData.Length //TODO: make a quick hash that can work clientside too
+            DataHash = CryptoGenericHashBlake2B.Hash(32, resource.ResourceData!, ReadOnlySpan<byte>.Empty)
         };
         _permittedBrowseRscFiles[filename] = resource;
 
@@ -384,7 +385,7 @@ public void HandleBrowseResourceRequest(string filename) {
         if(_permittedBrowseRscFiles.TryGetValue(filename, out var dreamResource)) {
             var msg = new MsgBrowseResourceResponse() {
                 Filename = filename,
-                Data = dreamResource.ResourceData! //honestly if this is null, something mega fucked up has happened and we should error hard
+                Data = dreamResource.ResourceData!, //honestly if this is null, something mega fucked up has happened and we should error hard
             };
             _permittedBrowseRscFiles.Remove(filename);
             Session?.Channel.SendMessage(msg);

OpenDreamRuntime/OpenDreamRuntime.csproj

@@ -16,6 +16,7 @@
     <PackageReference Include="Byond.TopicSender" />
     <PackageReference Include="Tracy-CSharp" />
     <PackageReference Include="OpenDreamByondApi" />
+    <PackageReference Include="SpaceWizards.Sodium" />
   </ItemGroup>
 
   <Import Project="..\RobustToolbox\MSBuild\Robust.Properties.targets" />

OpenDreamShared/Network/Messages/MsgBrowseResource.cs

@@ -8,15 +8,15 @@ public sealed class MsgBrowseResource : NetMessage {
     public override MsgGroups MsgGroup => MsgGroups.EntityEvent;
 
     public string Filename = string.Empty;
-    public int DataHash;
+    public byte[] DataHash = [];
 
     public override void ReadFromBuffer(NetIncomingMessage buffer, IRobustSerializer serializer) {
         Filename = buffer.ReadString();
-        DataHash = buffer.ReadVariableInt32();
+        DataHash = buffer.ReadBytes(32);
     }
 
     public override void WriteToBuffer(NetOutgoingMessage buffer, IRobustSerializer serializer) {
         buffer.Write(Filename);
-        buffer.WriteVariableInt32(DataHash);
+        buffer.Write(DataHash);
     }
 }